SUPERABSORVENT PARTICULATED POLYMERIC COMPOSITION WITH IMPROVED STABILITY AND FAST ABSORPTION

专利摘要:
particulate superabsorbent polymeric composition with improved stability and fast absorption. the present invention relates to a fast particulate superabsorbent polymeric composition comprising a polymer comprising a neutralized aluminum salt solution applied to the surface of a particulate superabsorbent polymer; wherein an aqueous solution of the neutralized aluminum salt has a pH value of about 5.5 to about 8; and subsequent to submitting the particulate superabsorbent polymeric composition to the processing test, the particulate superabsorbent polymeric composition has a permeability stability index of about 0.60 to about 0.99 and a compressibility of 1.30 mm2 / at about 4 mm2 / n as measured by the compression test and the particulate superabsorbent polymer composition can have a vortex time of 25 to 60 seconds and absorbance under load at 6.2 kpa (0.9 psi) of 15 to 21 g / g.
公开号:BR112015025521B1
申请号:R112015025521-3
申请日:2014-04-07
公开日:2020-12-15
发明作者:David L. Bergman；Gonglu Tian；Matthew Thomas Ondisco；Bernfried Messner；Scott J. Smith；Michael M. Azad；Mark Joy
申请人:Evonik Corporation；
IPC主号:

专利说明:

FIELD OF THE INVENTION
[0001] This application claims priority under 35 USC § 119 (e) for US Patent Application 13 / 860,019, filed on April 10, 2013, and for part-continuation of US Patent Application 14 / 157,769, filed on January 17, 2014, which are incorporated into this document as a reference in their entirety.
[0002] The present invention relates to particulate superabsorbent polymeric compositions that absorb water, aqueous liquids and blood, and a method for producing particulate superabsorbent polymeric compositions. In particular, the present invention relates to particulate superabsorbent polymeric compositions that have high permeability and improved stability of particulate superabsorbent polymeric compositions after processing. This invention is also aimed at improving the stability of the properties of particulate superabsorbent polymeric compositions, including permeability. BACKGROUND OF THE INVENTION
[0003] A superabsorbent polymer generally refers to a polymer, or material, that gels in the presence of water and is insoluble in water that has the capacity to absorb at least about 10 times the weight of it and up to about 30 times or more the weight in an aqueous solution containing 0.9 weight percent sodium chloride solution in water. Examples of superabsorbent polymer may include a neutralized and partially crosslinked acrylate polymer and the formation of superabsorbent hydrogel from polymerization and the formation of particulate superabsorbent polymeric compositions capable of holding aqueous liquids under a certain pressure according to the pressure. general definition of the superabsorbent polymer.
[0004] The superabsorbent polymer hydrogel can be formed in particles, generally referred to as particulate superabsorbent polymer, and the particulate superabsorbent polymer can be treated on the surface of it with a surface crosslinker and other surface treatment and post-treated afterwards. surface cross-linking to form particulate superabsorbent polymeric compositions. The acronym SAP can be used in place of superabsorbent polymer, superabsorbent polymeric composition, particulate superabsorbent polymeric compositions or variations thereof. Commercial particulate superabsorbent polymeric compositions are used widely in a variety of personal care products, such as baby diapers, child training diapers, adult incontinence products, female care products and the like. In general, these particulate superabsorbent polymeric compositions have a centrifugal retention capacity (CRC) of at least 25 grams of 0.9 percent by weight of aqueous sodium chloride solution per gram of the polymer. Particulate superabsorbent polymeric compositions are also designed to rapidly capture body fluids, which require a reasonable absorption speed, and are designed to rapidly distribute fluids in high concentrations, which requires high permeability, which can be measured as high permeability of gel bed (GBP). Commercial particulate superabsorbent polymeric compositions undergo significant processing during the manufacturing and conversion processes, which results in a lack of stability of the original gel bed permeability. This lack of stability or reduced value of various properties, including the gel bed permeability, may be one of the causes of the problems of premature leakage and skin moisture for absorbent articles.
[0005] Therefore, there is a need or desire for particulate superabsorbent polymeric compositions that can support the manufacturing and conversion processes of the absorbent product without resulting in a significant reduction in properties. There is also a need or desire for a method to increase the permeability stability of a particulate superabsorbent polymer composition. SUMMARY OF THE INVENTION
[0006] The present invention is directed to a particulate superabsorbent polymer composition that has improved stability and that comprises a particulate superabsorbent polymer that comprises about 0.05 to about 2.0% by weight based on the total amount of the unsaturated acid group. polymerizable containing the monomeric solution of a foaming agent and from about 0.001 to about 1.0% by weight based on the total amount of the polymerizable unsaturated acid group containing monomeric solution of a mixture of a lipophilic surfactant and a polyethoxylated hydrophilic surfactant and from 0.01% by weight to about 5% by weight based on the weight of the particulate superabsorbent polymer composition of a neutralized aluminum salt applied to the surface of the particulate superabsorbent polymer, in the form of an aqueous neutralized aluminum salt solution which has a pH value of about 5.5 to about 8; the particulate superabsorbent polymer composition having a centrifugal retention capacity of about 25 grams to about 40 grams of 0.9 weight percent aqueous sodium chloride per gram of the particulate superabsorbent polymer composition and an absorbance under load at 6 , 2 kPa (0.9 psi) before submitting the particulate superabsorbent polymeric composition to the Processing Test of 15 g / g to 21 g / g and has an original Free Dilatation Gel Bed Permeability (FSGBP) of about 30 x 10 -8 cm2 to about 200 x 10-8 cm2 before submitting the particulate superabsorbent polymeric composition to the Processing Test; has a Vortex time of 25 to 60 seconds as measured by the Vortex Test and has a permeability stability index of about 0.60 to about 0.99 when subjecting the particulate superabsorbent polymeric composition to a Processing Test and compressibility from 1.30 mm2 / N to about 4 mm2 / N as measured by the Compression Test. In general, properties are measured before Processing Test unless otherwise specified.
[0007] In addition, the present invention is directed to a particulate superabsorbent polymeric composition comprising a particulate superabsorbent polymer comprising an internal crosslinking agent comprising a silane compound comprising at least one vinyl group or allyl group and at least one bond Si-O, with the vinyl group or allyl group being directly attached to a silicon atom, and from 0.01% by weight to about 5% by weight based on the weight of the particulate superabsorbent polymeric composition of an aluminum salt neutralized applied to the surface of the particulate superabsorbent polymer, in the form of an aqueous neutralized aluminum salt solution having a pH value of about 5.5 to about 8; and the particulate superabsorbent polymeric composition has a Centrifugal Retention Capacity (CRC) of about 25 grams to about 40 grams of 0.9 weight percent aqueous sodium chloride per gram of the particulate superabsorbent polymeric composition, being that the CRC is measured before or after submitting the superabsorbent polymeric composition to a Processing Test, and an absorbance under load at 6.2 kPa (0.9 psi) before submitting the particulate superabsorbent polymeric composition to the Test Processing Speed of 15 g / g to 21 g / g and an original Free Dilatation Gel Bed Permeability (FSGBP) of about 30 x 10-8 cm2 to about 200 x 10-8 cm2 before submitting the particulate superabsorbent polymeric composition to the Processing Test and has a permeability stability index of about 0.60 to about 0.99 when submitting the particulate superabsorbent polymeric composition to a Processing Test and a compressibility of about 1, 30 mm2 / N to about 4 mm2 / N and an Increase in Centrifugal Retention Capacity (CRC) of 2 g / g or more based on Increase in CRC = CRC (tc, 5 h) - CRC (ta, 0, 5 h) in which the CRC Increase measures the increase in CRC that occurs and is calculated as the difference between the second CRC Test and the first CRC Test and tc refers to body temperature and ta refers to room temperature.
[0008] Additionally, the present invention is directed to a particulate superabsorbent polymeric composition that has improved stability comprising: a) from about 55% by weight to about 85% by weight of the polymerizable unsaturated acid group containing selected acid monomers acrylic, methacrylic acid or methylpropanesulfanoic acid-2-acrylamide or mixtures thereof; b) from about 14% by weight to about 45% by weight of an alkaline base selected from sodium hydroxide or potassium hydroxide to neutralize the polymerizable unsaturated acid group containing monomers of a) from about 50 to about 80 mol%; c) from about 0.001% by weight to about 5.0% by weight based on the weight of a) an internal crosslinking agent, d) from about 0.05 to about 2.0% by weight with based on the total amount of the polymerizable unsaturated acid group containing a monomeric solution of a foaming agent and from about 0.001 to about 1.0% by weight based on the total amount of the polymerizable unsaturated acid group containing monomeric solution of a mixture of lipophilic surfactant and a polyethoxylated hydrophilic surfactant, with components a), b), c) and d) being polymerized in a hydrogel that is granulated in the particulate superabsorbent polymer that has a surface; e) from about 0.001% by weight to about 5.0% by weight based on the weight of the particulate superabsorbent composition of the surface crosslinking agent applied to the surface of the particulate superabsorbent polymer; f) from 0.001% by weight to about 5.0% by weight based on the weight of the particulate superabsorbent composition of a neutralized aluminum salt applied to the surface of the particulate superabsorbent polymer, in the form of a neutralized aluminum salt solution aqueous which has a pH value of about 5.5 to about 8; the particulate superabsorbent polymer composition having a centrifugal retention capacity of about 25 grams to about 40 grams of 0.9 weight percent aqueous sodium chloride per gram of the particulate superabsorbent polymer composition and an absorbance under load at 6.2 kPa (0.9 psi) before submitting the particulate superabsorbent polymeric composition to the Processing Test of 15 g / g to 21 g / g and an original Dilation Free Gel Bed Permeability (FSGBP) of about 30 x 10 -8 cm2 to about 200 x 10-8 cm2 before submitting the particulate superabsorbent polymeric composition to the Processing Test and subsequently submitting the particulate superabsorbent polymeric composition to the Processing Test, the particulate superabsorbent polymeric composition presents a permeability stability index of about 0.60 to about 0.99 and a Vortex time of 25 to 60 seconds as measured by the Vortex Test and a compression bility 1.30 mm2 / N to about 4 mm2 / N as measured by the Compression Test.
[0009] With what has been mentioned in mind, it is a feature and advantage of the invention to provide the particulate superabsorbent polymeric composition that has improved permeability stability and methods of increasing the improved stability of the particulate superabsorbent polymeric composition. Numerous other features and advantages of the present invention will be apparent from the description below. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 is a side view of the Test apparatus employed for the Free Dilatation Gel Bed Permeability Test;
[0011] Figure 2 is a cross-sectional side view of a cup / cylinder assembly employed in the Free Dilatation Gel Bed Permeability Test apparatus shown in Figure 1;
[0012] Figure 3 is a top view of a plunger used in the Free Dilatation Gel Bed Permeability Test apparatus shown in Figure 1; and
[0013] Figure 4 is a side view of the Test apparatus used for the Absorbance Test under load. DEFINITIONS
[0014] Within the context of this specification, each term or expression below will include the following meaning (s).
[0015] It should be noted that, when used in the present disclosure, the terms "comprises", "which comprises" and other derivatives of the root term "understand" are intended to be open ended terms that specify the presence of any resources, elements , whole numbers, steps or components declared and are not intended to eliminate the presence or addition of one or more other resources, elements, whole numbers, steps, components or groups thereof.
[0016] As used herein, the term "about" which modifies the amount of an ingredient in the compositions of the invention or used in the methods of the invention refers to the variation in the numerical amount that can occur, for example, in handling procedures. typical liquid and measurement to produce concentrates or use typical liquid handling and measurement procedures to produce concentrates or use real-world solutions; through inadvertent error in these procedures; through differences in the manufacture, source or purity of the ingredients used to produce the compositions or carry out the methods and the like. The term "about" also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial blend. Modified or not by the term "about", the claims include equivalent amounts.
[0017] The term "Centrifugal Holding Capacity (CRC)" as used in this document refers to the ability of the particulate superabsorbent polymer to retain liquid in it after being saturated and subjected to centrifugation under controlled conditions and is stated in grams of retained liquid per gram of sample weight (g / g) as measured by the Centrifugal Retention Capacity Test set out in this document.
[0018] The term "Increase in Centrifugal Retention Capacity (CRCI)" or "Increase in CRC" or "Increase in Capacity" is defined as the increase in CRC that occurs and is calculated as the difference between a second CRC and a first CRC. As used in this document, the term "first CRC" or "initial CRC" generally refers to CRC (ta, 0.5 h) where ta refers to an ambient temperature of about 23 ° C, despite another CRC value can be used. The "second CRC" can be tested at or above body temperature, preferably about 37 ° C, for at least about 1 hour, preferably about 2 hours to 24 hours. CRC Increase is measured according to the CRC Increase Test Method described in this document below.
[0019] The term "compressibility" as used herein refers to a measure of the relative volume change of the particulate superabsorbent polymer composition as a response to a pressure change as set out below in a Compressibility Test herein.
[0020] The terms "lattice", "lattice", "lattice" or "lattice" as used herein refer to any means to effectively make materials normally water-soluble substantially insoluble in water, but with the capacity to gel . Such a crosslinking medium may include, for example, physical tangle, crystalline domains, covalent bonds, ionic associations and complexes, hydrophilic associations such as hydrogen bonding, hydrophobic associations or Van der Waals forces.
[0021] The term "internal crosslinker" or "monomer crosslinker" as used herein refers to the use of a crosslinker in the monomeric solution to form the polymer.
[0022] The term "dry particulate superabsorbent polymeric composition" as used in this document, in general, refers to the superabsorbent polymeric composition that has less than about 20% moisture.
[0023] The term "gel permeability" is a property of the mass of particles as a whole and is related to the distribution of particle size, particle shape and the connectivity of the open pores between the particles, shear modulus and surface modification of the dilated gel. In practical terms, the gel permeability of the superabsorbent polymeric composition is a measure of how fast the liquid flows through the mass of swollen particles. Low gel permeability indicates that the liquid cannot flow readily through the superabsorbent polymeric composition, which is generally referred to as a gel blocker, and that any forced flow of liquid (such as a second application of urine during diapering) needs travel an alternative path (for example, diaper leak).
[0024] The acronym "HLB" means the hydrophilic-lipophilic balance of a surfactant and is measured from the degree to which it is hydrophilic or lipophilic, as determined when calculating values for the different regions of the molecule. The HLB value can be used to predict the surfactant properties of a molecule in which an HLB value <10 is soluble in lipid (insoluble in water) and an HLB value> 10 is soluble in water (insoluble in lipid).
[0025] The terms "particle", "particulate" and the like, when used with the term "superabsorbent polymer" refer to the shape of the discrete units. The units may comprise flakes, fibers, agglomerates, granules, powders, spheres, pulverized materials or the like, as well as combinations thereof. The particles can have any desired shape: for example, cubic, polyhedron similar to the rod, spherical or semi-spherical, rounded or semi-rounded, angular, irregular, etc.
[0026] The terms "particulate superabsorbent polymer" and "particulate superabsorbent polymeric composition" refer to the form of the superabsorbent polymer and the superabsorbent polymeric compositions in discrete form, with the "particulate superabsorbent polymer" and the "particulate superabsorbent polymeric compositions" - ladas "can have a particle size of less than 1,000 μm or from about 150 μm to about 850 μm.
[0027] The term "permeability", when used in this document, should mean a measure of the effective connectivity of a pore structure, in this case, crosslinked polymers and can be specified in terms of the fraction of empty space and extension of the connection of the particulate superabsorbent polymeric composition.
[0028] The term "permeability stability index" when used in this document should mean the ability of the particulate superabsorbent polymer to maintain the original permeability after being subjected to a Processing Test under controlled conditions. The same refers to the ratio of the permeability of the processed sample to the permeability of the original sample as established in a Processing Test described in this document.
[0029] The term "polymer" includes, but is not limited to, homopolymers, copolymers, for example, copolymer, terpolymers, etc., in block, graft, random and alternating and blends and modifications thereof. In addition, unless specifically limited otherwise, the term "polymer" should include all possible configurational isomers of the material. These configurations include, but are not limited to, isotactic, syndiotactic and atomic symmetries.
[0030] The term "polyolefin" as used in this document generally includes, but is not limited to, materials such as polyethylene, polypropylene, polyisobutylene, polystyrene, ethylene vinyl acetate copolymer and the like, homopolymers , copolymers, terpolymer, etc., of the same and mixtures and modifications thereof. The term "polyolefin" must include all possible structures of the same, which include, but are not limited to, isotactic, synodiotactic and random symmetries. Copolymers include atactic and block copolymers.
[0031] The term "polysiloxane" as used in this document refers to polymerized siloxanes consisting of an inorganic silicon-oxygen structure (...- Si-O-Si-O-Si-O -...) with organic side groups linked to silicon atoms, which are coordinated in four. In addition, unless otherwise specified, the term "polysiloxane" should include polymers that comprise two or more siloxane breakdown units.
[0032] The term "superabsorbent polymer" as used in water-insoluble inorganic or organic materials and which gel in water including superabsorbent polymers and superabsorbent polymeric compositions capable of, under the most favorable conditions, absorbing at least about 10 times the size of the same, or at least about 15 times the size of the same, or at least about 25 times the weight of the same in an aqueous solution containing 0.9 weight percent sodium chloride.
[0033] The term "superabsorbent polymeric composition" as used herein refers to a superabsorbent polymer comprising a surface additive according to the present invention.
[0034] The term "surface crosslinking" as used in this document refers to the level of functional crosslinkers in the vicinity of the particle surface of the superabsorbent polymer, which is, in general, greater than the level of functional crosslinkers within the particle of superabsorbent polymer. As used in this document, "surface" describes the outer limits of the particle.
[0035] The term "thermoplastic" as used in this document describes a material that softens when exposed to heating and which substantially returns to an un Softened condition when cooled to room temperature.
[0036] The term "vortex time" measures the amount of time in seconds required for 2 grams of an SAP to close a vortex created by shaking 50 milliliters of saline at 600 revolutions per minute on a magnetic stirring plate. The time it takes for the vortex to close is an indication of SAP's free growth absorption rate.
[0037] The term "% by weight" or "% by weight" as used herein refers to the components of the dry particulate superabsorbent polymer composition and should be interpreted as based on the weight of the dry superabsorbent polymeric composition, unless otherwise specified in this document.
[0038] The term "moisture content" when used in this document must mean the amount of water contained in the particulate superabsorbent polymer composition as measured by the Moisture Content Test.
[0039] These terms can be defined with additional language in the remaining parts of the specification. DETAILED DESCRIPTION OF THE INVENTION
[0040] Although typical aspects of the modality and / or modalities have been established for the purpose of illustration, this Detailed Description and the accompanying drawings should not be considered as a limitation of the scope of the invention. In this way, several modifications, adaptations and alternatives can occur for the one skilled in the art without departing from the spirit and scope of the present invention. By means of a hypothetical illustrative example, a disclosure in this specification of a range from 1 to 5 should be considered as supporting claims within any of the following ranges: 1 to 5; 1 to 4; 1 to 3; 1 to 2; 2 to 5; 2 to 4; 2 to 3; 3 to 5; 3 to 4 and 4 to 5.
[0041] According to the invention, a particulate superabsorbent polymeric composition that has improved stability can be achieved by using the methods described in this document. These particulate superabsorbent polymeric compositions that have improved stability have improved the processing resistance of the particulate superabsorbent polymeric composition and reduced functional loss compared to the current commercially available particulate superabsorbent polymeric composition.
[0042] In another embodiment, the present invention is directed to a particulate superabsorbent polymer composition that has improved stability that comprises a particulate superabsorbent polymer that comprises about 0.05 to about 2.0% by weight based on the total amount of the polymerizable unsaturated acid group containing monomeric solution of a foaming agent and from about 0.001 to about 1.0% by weight based on the total amount of the polymerizable unsaturated acid group containing monomeric solution of a mixture of lipophilic surfactant and a hydrophilic surfactant polyethoxylated and from 0.01% by weight to about 5% by weight based on the weight of the particulate superabsorbent polymeric composition of a neutralized aluminum salt applied to the surface of the particulate superabsorbent polymer, in the form of a salt solution aqueous neutralized aluminum which has a pH value of about 5.5 to about 8; the particulate superabsorbent polymer composition having a centrifugal retention capacity of about 25 grams to about 40 grams of 0.9 weight percent aqueous sodium chloride per gram of the particulate superabsorbent polymer composition and an absorbance under load at 6.2 kPa (0.9 psi) before submitting the particulate superabsorbent polymeric composition to the Processing Test of 15 g / g to 21 g / g and an original Free Dilatation Gel Bed Permeability (FSGBP) of about 30 x 10 -8 cm2 to about 200 x 10-8 cm2 before subjecting the treated particulate superabsorbent polymer composition to a Processing Test; and the particulate superabsorbent polymeric composition has a Vortex time of 25 to 60 seconds as measured by the Vortex Test and has a permeability stability index of about 0.60 to about 0.99 when submitting the polymeric composition superabsorbent particulate to a Processing Test and a compressibility of 1.30 mm2 / N to about 4 mm2 / N as measured by the Compression Test.
[0043] Additionally, the present invention is directed to a particulate superabsorbent polymeric composition that has improved stability comprising: a) from about 55% by weight to about 85% by weight of the polymerizable unsaturated acid group containing monomers selected from acrylic acid, methacrylic acid or methylpropanesulfonic acid-2-acrylamido-2 or mixtures thereof; b) from about 14% by weight to about 45% by weight of an alkaline base selected from sodium hydroxide or potassium hydroxide to neutralize the polymerizable unsaturated acid group containing monomers from a) to about 50 to about 80 mol%. c) from about 0.001% by weight to about 5.0% by weight based on the weight of a) an internal crosslinking agent; d) from about 0.05 to about 2.0% by weight based on the total amount of the polymerizable unsaturated acid group containing a monomeric solution of a foaming agent and from about 0.001 to about 1.0% in weight based on the total amount of the polymerizable unsaturated acid group containing monomeric solution of a mixture of lipophilic surfactant and a polyethoxylated hydrophilic surfactant, with components a), b), c) and d) being polymerized in a hydrogel which it is granulated in particulate superabsorbent polymer that has a surface; e) from about 0.001% by weight to about 5.0% by weight based on the weight of the particulate superabsorbent composition of surface crosslinking agent applied to the surface of the particulate superabsorbent polymer; f) from 0.001% by weight to about 5.0% by weight based on the weight of the particulate superabsorbent composition of a neutralized aluminum salt applied to the surface of the particulate superabsorbent polymer, in the form of a neutralized aluminum salt solution aqueous which has a pH value of about 5.5 to about 8; the particulate superabsorbent polymer composition having a centrifugal retention capacity of about 25 grams to about 40 grams of 0.9 weight percent aqueous sodium chloride per gram of the particulate superabsorbent polymer composition and an absorbance under load at 6 , 2 kPa (0.9 psi) before submitting the particulate superabsorbent polymeric composition to the Processing Test of 15 g / g to 21 g / g and an original Free Expansion Gel Bed Permeability (FSGBP) of about 30 x 10- 8 cm2 to about 200 x 10-8 cm2 before submitting the treated particulate superabsorbent composition to the Processing Test and subsequent to submitting the treated particulate superabsorbent composition to the Processing Test the treated particulate superabsorbent composition has a stability index permeability of about 0.60 to about 0.99 when submitting the particulate superabsorbent polymeric composition to a Processing Test and o in Vortex from 25 to 60 seconds as measured by the Vortex Test and a compressibility from 1.30 mm2 / N to about 4 mm2 / N as measured by the Compression Test.
[0044] In another embodiment, the invention is directed to the production of a particulate superabsorbent polymeric composition comprising the following steps: A) preparing a process to produce a particulate superabsorbent polymer that has rapid water absorption comprising the steps of a) preparing an aqueous monomeric solution of a mixture of the polymerizable unsaturated acid group containing monomer and an internal crosslinking agent monomer, the aqueous monomeric solution comprising dissolved oxygen; b) spraying the aqueous monomeric solution from step a) which includes adding an inert gas to the aqueous monomeric solution from step a) to replace the dissolved oxygen from the aqueous monomeric solution; c) polymerize the aqueous monomeric solution of step b) which includes the steps of c1) add to the aqueous monomeric solution of step a): i) an aqueous solution comprising about 0.05 to about 2.0% by weight based on the total amount of the polymerizable unsaturated acid group containing monomeric solution of a foaming agent and ii) an aqueous solution comprising from about 0.001 to about 1.0% by weight based on the total amount of the insatu acid group - polymerizable feed containing monomeric solution of a mixture of lipophilic surfactant and a hydrophilic polyethoxylated surfactant; c2) treating the monomeric solution from step c1) with high speed shear mixing to form treated monomeric solution, the components of which i) an aqueous solution comprising about 0.1 to about 1.0% by weight of a foaming agent and ii) an aqueous solution comprising about 0.001 to about 1.0% by weight of a mixture of lipophilic surfactant and a polyethoxylated hydrophilic surfactant are added to the aqueous monomeric solution after step b) of spraying the solution aqueous monomeric and before step c2) high speed shear mixing of the aqueous monomeric solution; c3) forming a hydrogel by adding a polymerization initiator to the monomeric solution treated in step c2) with the initiator being added to the monomeric solution treated after the foaming agent and the mixture of surfactants, the polymer being formed to include bubbles foaming agent in the polymer structure; and d) drying and grinding the hydrogel of step c) to form particulate superabsorbent polymer; and e) crosslinking the surface of the superabsorbent polymer particularly from step d) with a crosslinking agent; B) preparing a neutralized aluminum salt in the form of an aqueous solution which has a pH value of about 5.5 to about 8; and C) applying the aqueous neutralized aluminum salt solution to the surface of the particulate superabsorbent polymer; and the particulate superabsorbent polymer composition has a degree of neutralization of about 50 mol to about 80 mol% and the particulate superabsorbent polymer composition has a Centrifugal Retention Capacity of about 25 grams at about 40 grams of 0.9 weight percent aqueous sodium chloride per gram of the particulate superabsorbent polymeric composition, the CRC being measured before or after submitting the superabsorbent polymeric composition to a Processing Test and an absorbance under load at 6.2 kPa (0.9 psi) before submitting the particulate superabsorbent polymeric composition to the Processing Test of 15 g / g 21 / g and a Free Dilatation Gel Bed Permeability (FSGBP) of about 30x10-8 cm2 to about 200 x 10-8 cm2 before submitting the treated superabsorbent particulate composition to the Processing Test; presents a permeability stability index of about 0.60 to about 0.99 when submitting the particulate superabsorbent polymeric composition to a Processing Test and the 1.30 mm2 / N compressibility to about 4 mm2 / N as measured by the Compression Test, and the cross-linked superabsorbent polymer on the surface has a vortex of about 25 seconds to about 60 seconds.
[0045] The present invention is also directed to a particulate superabsorbent polymeric composition that has improved stability comprising a particulate superabsorbent polymer comprising a silane compound crosslinker comprising at least one vinyl group or allyl group and at least one Si bond. The vinyl group or allyl group is directly attached to a silicon atom, with the particulate superabsorbent polymer having an Increase in Centrifugal Retention Capacity (CRC) of 2 g / g or more based on Increase in CRC = CRC (tc, 5 h) - CRC (ta, 0.5 h) and the CRC Increase measures the increase in CRC that occurs and is calculated as the difference between the second CRC Test and the first CRC Test and tc refers to body temperature and ta refers to room temperature and from 0.01% by weight to about 5% by weight based on the particulate superabsorbent polymeric composition weight of a neutralized aluminum salt applied to the surface of the poly particulate superabsorbent, in the form of an aqueous neutralized aluminum salt solution having a pH value of about 5.5 to about 8; the particulate superabsorbent polymer composition having a centrifugal retention capacity of about 25 grams to about 40 grams of 0.9 weight percent aqueous sodium chloride per gram of the particulate superabsorbent polymer composition; and an absorbance under load at 6.2 kPa (0.9 psi) before submitting the particulate superabsorbent polymeric composition to the Processing Test of 15 g / g to 21 g / g; and an original Free Dilatation Gel Bed Permeability (FSGBP) of about 30 x 10-8 cm2 to about 200 x 10-8 cm2 before subjecting the particulate superabsorbent polymeric composition to a Processing Test; presents a permeability stability index of about 0.60 to about 0.99 when submitting the particulate superabsorbent polymeric composition to a Processing Test and a compressibility of about 1.30 mm2 / N to about 4 mm2 / N as measured by the Compression Test.
[0046] A suitable superabsorbent polymer can be selected from synthetic, natural, biodegradable and modified natural polymers. The term cross-linked used in reference to the superabsorbent polymer refers to any means to effectively make materials normally soluble in water and substantially insoluble in water, but swellable. Such a crosslinking medium can include, for example, physical entanglement, crystalline domains, covalent bonds, ionic complexes and associations, hydrophilic associations such as hydrogen bonding, hydrophobic associations or Van der Waals forces. Superabsorbent polymers include internal crosslinking and may additionally include surface crosslinking.
[0047] A superabsorbent polymer as established in the modalities of the present invention can be obtained by the initial polymerization of about 55% to about 99.9% by weight of the superabsorbent polymer of the polymerizable unsaturated acid group containing monomer. A suitable monomer includes any of those containing carboxyl groups, such as acrylic acid or methacrylic acid; or methylpropanesulfonic acid-2-acrylamido-2 or mixtures thereof. It is desirable that at least about 50% by weight and more desirable that at least about 75% by weight of the acid groups are carboxyl groups.
[0048] The process of producing a superabsorbent polymer as established in the modalities of the present invention can be obtained by the initial polymerization of about 55% to about 99.9% by weight of the superabsorbent polymer of the polymerizable unsaturated acid group that contains monomer. A suitable polymerizable monomer includes any of those containing carboxyl groups, such as acrylic acid, methacrylic acid or methylpropanes-sulfonic-2-acrylamide-2 or mixtures thereof. It is desirable that at least about 50% by weight and more desirable that at least about 75% by weight of the acid groups are carboxyl groups.
[0049] The acid groups are neutralized with an alkali metal base to the extent of at least about 25 mol% or from about 50 mol% to about 80 mol%, that is, the acid groups are desirably present like sodium, potassium or ammonia salts. The amount of alkaline base can be from about 14% by weight to about 45% by weight of the particulate superabsorbent polymer composition. The alkaline base can include sodium hydroxide or potassium hydroxide. In some aspects, it is desirable to use polymers obtained by polymerizing acrylic acid or methacrylic acid, whose carboxyl groups are neutralized in the presence of internal cross-linking agents. It is observed that neutralization can be achieved by adding the alkaline base to the monomeric solution or by adding the monomer such as acrylic acid to the alkaline base.
[0050] In some respects, the second suitable monomer that can be copolymerized with the ethylenically unsaturated monomer may include, but is not limited to, acrylamide, methacrylamide, hydroxyethyl acrylate, dimethylaminoalkyl (meth) acrylate, (meth) acrylates, dimethylamide and acrylate) or acrylamidopropyltrimethylammonia chloride. Such a monomer can be present in a range from 0% by weight to about 40% by weight of the copolymerized monomer.
[0051] In the case where the monomer is acrylic acid, the partially neutralized acrylate salt is transformed into the polymer in the particulate water-absorbing agent after polymerization, the value converted based on the acrylic acid can be determined by converting the salt partially neutralized polyacrylate which is estimated to be entirely equimolar non-neutralized polyacrylic acid.
[0052] The superabsorbent polymer of the invention also includes from about 0.001% by weight to about 5% by weight or from about 0.2% by weight to about 3% by weight based on the total amount of the unsaturated acid group polymerizable containing monomer of at least one internal crosslinking agent. The internal cross-linking agent generally has at least two ethylenically unsaturated double bonds or an ethylenically unsaturated double bond and a functional group that is reactive towards the acid groups of the polymerizable unsaturated acid group that contains monomers or several functional groups that are reactive in Regarding the acid groups, they can be used for the internal cross-linking component which is present during the polymerization of the polymerizable unsaturated acid group containing monomers.
[0053] Examples of internal crosslinking agents used in superabsorbent polymers include aliphatic unsaturated amides, such as methylenebisacryl- or -methacrylamide or ethylenebisacrylamide and, in addition, aliphatic esters of polyols or alkoxylated polyols with ethylenically unsaturated acids (such as di) or butanediol or ethylene glycol tri (meth) acrylates, polyglycols or trimethylol-propane, trimethylolpropane di- and triacrylate esters which is preferably oxyalkylated, preferably ethoxylated, with 1 to 30 moles of alkylene oxide, acrylate esters and glycol methacrylate and penterythritol and glycerol and oxyethylated pentaerythritol with preferably 1 to 30 mol of ethylene oxide and, in addition, allyl compounds such as allyl (meth) acrylate, allyl (meth) acrylate reacted preferably with 1 to 30 moles ethylene oxide, trialyl cyanurate, trialyl isocyanurate, maleic acid dially ester, polyallyl esters, trimethoxy vinyl isosilane, vinyl triethoxysilane, polysiloxane comprising at least two vinyl groups, tetraalkyloxyethane, tetraalkyloxyethane, trialylamine, teethylethylenediamine, diois, polyols, allyl hydroxyl or acrylate compounds and allyl esters of phosphoric acid or phosphoric acid and, additionally, monomers that are capable of crosslinking, such as N-methylol compounds from unsaturated amides, such as methacrylamide or acrylamide, and the esters derived therefrom. Ionic crosslinkers such as aluminum metal salts can also be employed. Mixtures of the mentioned crosslinking agents can also be used.
[0054] The internal crosslinking agent may contain a silane compound comprising at least one vinyl group or allyl group directly attached to a silicon atom and at least one Si-O bond. The silane compound can be selected from one of the following:


where R1 represents C2 to C3 alkenyl, R2 represents H, C1 to C4 alkyl, C2 to C5 alkenyl, C6 to C8 aryl, C2 to C5 carbonyl, R3 represents H, C1 to C4 alkyl, C6 to C8 aryl, R4 and R5 independently represent H, C1 to C4 alkyl, C6 to C8 aryl, m represents an integer from 1 to 3, preferably 1 to 2, n represents an integer from 1 to 3, preferably 2 to 3, l represents an integer from 0 to 2, preferably 0 to 1, m + n + 1 = 4, x represents an integer greater than 1, and y represents an integer 0 or greater than 0.
[0055] Illustrations of silanes, which have at least one vinyl group or allyl group directly attached to a silicon atom and a Si-O bond, which can be used to provide the structure in formula (I) above include: vinylalkoxysilanes such as vinyltrimethoxysilane, methyl vinyltrimethoxysilane, vinyltriethoxysilane, methylvinyltriethoxysilane, vinylmethyldimethoxysilane, vinyl ethyl diethoxysilane and vinyltris (2-methoxyethoxy) silane; vinylacetoxysilanes, such as vinylmethyldiacethoxysilane, vinylethylthiaxoxysilane and vinyltriacetoxy silane; allylalkoxysilanes such as allyltrimethoxysilane, allylmethyldimethoxysilane and allyltriethoxysilane; divinylalkoxysilanes and divinylacetoxysilanes such as divinyldimethoxysilane, divinyldiethoxysilane and divinyldiacethoxysilane; diallylalkoxysilanes and diallyl ethoxysilanes such as diallyldimethoxysilane, diallyldiethoxysilane and diallyldiaketoxy silane; as well as other similar ethylenically unsaturated silane monomers that contain one or more hydroxy groups. As will be appreciated by a person skilled in the art related to the present disclosure, the use of compounds such as vinyltrichlorosilane in water or alcohol can provide structures in formula (I) above in which, for example, the group R1 may be a vinyl group. It is also possible that more complex structures can be formed, for example, by reacting vinyl silane with polyethylene glycol.
[0056] Illustrations of polysiloxanes, which have at least one vinyl group or allyl group directly attached to a silicon atom, which can be used to provide the structure in formula (II) or (III) above include the polymers and copolymers of silanes that have the structure in formula (I). Preferred examples include, but are not limited to, polysiloxane comprising vinyl and methoxy groups (commercially available from Evonik Degussa Corporation, branded Dynasylan® 6490), polysiloxane comprising vinyl and ethoxy groups (commercially available from Evonik Degussa Corporation, with brand Dynasylan® 6498), vinylmethylsiloxane homopolymers, vinylmethylsiloxane copolymers, siloxane homopolymers with vinyl termination and siloxane copolymers with vinyl termination. However, it is observed that a wide range of polysiloxanes having vinyl functional groups that provide the desired effects are effective crosslinking agents according to the present invention.
[0057] Examples of internal silane crosslinkers suitable for the present invention are set out with their chemical structure in Table 1. TABLE 1


[0058] In another embodiment, the superabsorbent polymer can include from about 0.001% by weight to about 0.1% by weight based on the total amount of the polymerizable unsaturated acid group that contains monomer from a second internal crosslinker which can comprise compositions which comprise at least two ethylenically unsaturated double bonds, for example, methylenebisacrylamide or -methacrylamide or ethylenebisacrylamide; in addition, esters of polyunsaturated mono- or polycarboxylic acids, such as diacrylates or triacrylates, for example, butanediol- or ethylene glycol diacrylate or -methacrylate; trimethylolpropane triacrylate, as well as the alkoxylated derivatives thereof; in addition, allyl compounds, such as allyl (meth) acrylate, trialyl cyanurate, maleyl acid diallyl ester, polyallyl ester, tetralyloxyethane, di- and trialylamine, tetralylethylenediamine, phosphoric acid or phosphoric acid allyl esters. In addition, compounds that have at least one functional group reactive to acidic groups can also be used. Examples of these include N-methylol amide compounds, such as methacrylamide or acrylamide and the esters derived therefrom, as well as di- and polyglycidyl compounds.
[0059] The present invention further includes from about 0.05 to about 2.0% by weight, or from about 0.1 to about 1.0% by weight, based on the total amount of the unsaturated acid group polymerizable containing monomeric solution of a foaming agent. The foaming agent can include any alkali metal carbonate or alkali metal bicarbonate that contains salt, or mixed salt, sodium carbonate, potassium carbonate, ammonia carbonate, magnesium carbonate or (hydroxide) magnesium carbonates, calcium carbonate, barium carbonate, bicarbonates and hydrates thereof, azo compounds or other cations, as well as naturally occurring carbonates, such as dolomite, or mixtures thereof. Foaming agents can include carbonate salts of multivalent cations, such as Mg, Ca, Zn and the like. Although certain multivalent transition metal cations can be used, some of them, such as ferric cation, can cause color staining and can undergo reduction-oxidation reactions or hydrolysis balance in water. This can lead to difficulties in quality control of the final polymeric product. In addition, other multivalent cations, such as Ni, Ba, Cd, Hg would be unacceptable because of the potential effects of skin sensitivity and toxicity. Foaming agents can include sodium carbonate and sodium bicarbonate.
The present invention further includes an aqueous solution comprising about 0.001 to about 1.0% by weight, or from about 0.002 to about 0.5% by weight, or from about 0.003 to about 0 , 1% by weight, based on the total amount of the polymerizable unsaturated acid group containing monomeric solution of a mixture of lipophilic surfactant and a polyethoxylated hydrophilic surfactant, with the lipophilic surfactant having an HLB of 4 to 9 and the surfactant hydrophilic polyethoxylate has an HLB of 12 to 18; or the lipophilic surfactant may be non-ionic or the polyethoxylated hydrophilic surfactant may be non-ionic.
[0061] Typical examples of the surfactant, aryl alkyl ethylene polyoxy ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ethers such as ethers of higher polyoxyethylene alcohol and polyethylene nonyl polyether ether ; fatty esters of sorbitan such as sorbitan monolamate, sorbitan monopalmitate, sorbitan monostearate, sorbitan trisearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate and sorbitan distearate; polyoxyethylene sorbitan fatty esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate and polyoxyethylene; polyoxyethylene sorbitol fatty esters such as polyoxyethylene sorbitan of tetraoleic acid; fatty esters of glycerin such as glycerol monostearate, glycerol monooleate and selfemulsifying glycerol monostearate; polyoxyethylene fatty esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate and polyethylene glycol monooleate; polyoxyethylene alkyl amines; hardened polyoxyethylene maize oil and alkyl alcohol amines can be cited. The mixture of nonionic surfactant can include a mixture of lipophilic surfactant which is a sorbitan ester and polyethoxylated hydrophilic surfactant which is a polyethoxylated sorbitan ester.
[0062] Common initiators, such as, for example, azo or peroxide compounds, redox systems or UV (sensitizer) and / or radiation initiators are used to initiate free radical polymerization. In some respects, primers can be used to initiate free radical polymerization. Suitable initiators include, but are not limited to, azo or peroxide compounds, redox systems or ultraviolet initiators, sensitizers and / or radiation.
[0063] Polymerization forms a superabsorbent polymer gel, which is granulated into particles of superabsorbent polymer or particulate superabsorbent polymer. The superabsorbent polymer gel generally has a moisture content of about 40 to 80% by weight of the superabsorbent polymer gel. The reaction time is not particularly limited, but is only required to be established depending on the combination of an unsaturated monomer, a crosslinking agent and a radical polymerization initiator or in such reaction conditions as the reaction temperature.
[0064] The particulate superabsorbent polymer generally includes particle sizes ranging from about 50 μm to about 1,000 μm, or from about 150 μm to about 850 μm. The present invention can include at least about 40% by weight of the particles having a particle size of about 300 μm to about 600 μm, at least about 50% by weight of the particles having a particle size of about 300 μm to about 600 μm, or at least about 60% by weight of particles that have a particle size of about 300 μm to about 600 μm as measured by screening through the US standard 30 mesh screen and retained on a US standard 50 mesh fabric. In addition, the particle size distribution of the superabsorbent polymer of the present invention can include less than about 30% by weight of particles having a size greater than about 600 µm and less than about 30% by weight of particles which have a size of less than about 300 μm and 0 to 5% by weight of particles smaller than 150 μm, as measured by the use, for example, of a RO-TAP® model B mechanical sieve shaker available by WS Tyler, Inc., Mentor Ohio.
[0065] In another embodiment of the particulate superabsorbent polymer of the present invention, the diameter of the resin particle is established as follows. The mass-average particle diameter is generally about 200 to about 450 μm or about 300 to about 430 μm or about 300 to about 400 μm or about 350 to about 400 μm or from about 360 to about 400 μm or from about 370 to about 400 μm. In addition, the percentage of particles smaller than 150 μm is generally from 0 to about 8% by weight or from 0 to about 5% by weight or from 0 to about 3% by weight or from 0 to about 1% in weight. In addition, the percentage of particles larger than 600 μm is generally 0 to about 25% by weight or 3 to about 15% by weight or 5 to about 12% by weight or 5 to about 8 % by weight.
[0066] The particle size can be adjusted by subjecting the particles to dispersion polymerization and dispersion drying. However, in general, when carrying out the aqueous polymerization in particular, the particles are pulverized and classified after drying and then the mass average diameter of D50 and the quantity of particles smaller than 150 μm and larger than 600 μm are adjusted in order to obtain a specific particle size distribution. For example, if the specific particle size distribution is achieved by decreasing the diameter of particles that have a mass average diameter of D50 to 400 μm or less and also by reducing the amount of fine particles that have a diameter less than 150 μm and greater than 600 μm, the particles can be classified primarily as coarse particles and fine particles after drying by using generic classification equipment such as a sieve. This process preferably removes coarse particles with a diameter of 5,000 μm to 600 μm or 2,000 μm to 600 μm, or 1,000 μm to 600 μm. Then, in the main adjustment process, fine particles with a diameter of less than 150 μm are removed. The coarse particles removed can be discarded, but they are more likely to be sprayed again through the previous spraying process. The resulting particulate superabsorbent polymer is therefore produced with a specific particle size distribution through the spraying process, thus constituted of irregularly sprayed particles.
[0067] Particulate superabsorbent polymers are surface treated with additional chemicals and treatments as set out in this document. In particular, the surface of the particulate superabsorbent polymer is crosslinked, generally called surface crosslinking, by the addition of a surface crosslinking agent and heat treatment. In general, surface crosslinking is a process for increasing the density of the polymer matrix crosslinker in the vicinity of the particulate superabsorbent polymer surface with respect to the crosslinker density of the interior of the particle. The amount of the surface crosslinking agent can be present in an amount of about 0.01% by weight to about 5% by weight of the dry particulate superabsorbent polymer composition and such as about 0.1% by weight at about 3% by weight and such as from about 0.1% by weight to about 1% by weight, based on the weight of the dry particulate superabsorbent polymer composition.
[0068] Desirable surface crosslinking agents include chemicals with one or more functional groups that are reactive with respect to groups suspended from polymer chains, typically acid groups. Surface crosslinking agents comprise functional groups which react with functional groups of a polymer structure in a condensation reaction (condensation crosslinker), in an addition reaction or in a ring opening reaction. Such compounds may include, for example, methylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymers, sorbitan fatty acid esters, esters of sorbitan fatty acid polyoxyethylene, trimethylol-propane, pentaerythritol, polyvinyl alcohol, oxazolidones such as 2-oxazolidinone, N-methyl-2-oxazolidone, N-hydroxyethyl-2-oxazolidone and N-hydroxypropyl-2-oxazolidone, sorbitol, 1 , 3-dioxolan-2-one (ethylene carbonate), 4-methyl-1,3-dioxolan-2-one (propylene carbonate) or 4,5-dimethyl-1,3-dioxolan-2-one.
[0069] After the particulate superabsorbent polymer has been brought into contact with the surface crosslinking agent or with the fluid comprising the surface crosslinking agent, the treated particulate superabsorbent polymer is heated to a temperature of about 50 to about 300 ° C, or about 75 to about 275 ° C, or about 150 to about 250 ° C and for a time of about 5 to about 90 minutes depending on the temperature, so that the outer region of the polymer structures is more strongly cross-linked compared to the inner region (ie, surface cross-linking). The duration of the heat treatment is limited by the risk that the desired property profile of the polymer structures is destroyed as a result of the heating effect.
[0070] In a particular aspect of the surface crosslinking, the particulate superabsorbent polymer is treated on the surface of it with ethylene carbonate followed by heating to perform the surface crosslinking of the superabsorbent polymer particle, which improves the density of surface crosslinker and the strength characteristics of the particulate superabsorbent polymer gel. More specifically, the surface crosslinking agent is re-coated in the particulate superabsorbent polymer by mixing the particulate superabsorbent polymer with an aqueous alcoholic solution of the ethylene carbonate surface crosslinking agent. The amount of alcohol in the aqueous alcoholic solution can be determined by the solubility of the alkylene carbonate and is kept as low as possible for several reasons, for example, for protection against explosions and, in some cases, can be omitted entirely. Suitable alcohols are methanol, isopropanol, ethanol, butanol or butyl glycol, as well as mixtures of these alcohols. In some respects, the solvent is desirably water, which is typically used in an amount of about 0.3 wt% to about 5.0 wt%, based on the weight of the dry particulate superabsorbent polymer composition. In still other aspects, the ethylene carbonate surface crosslinking agent can be applied from a powder mixture, for example, with an inorganic carrier material, such as silicon dioxide (Si02) or in a state of steam by sublimation of ethylene carbonate.
[0071] To achieve the desired surface crosslinking properties, surface crosslinking agents such as ethylene carbonate must be evenly distributed in the particulate superabsorbent polymer. For this purpose, mixing is carried out in suitable mixers known in the art, such as fluidized bed mixers, paddle mixers, rotary drum mixers or double screw mixers. It is also possible to coat the particulate superabsorbent polymer during one of the process steps in the production of the particulate superabsorbent polymer. In a particular aspect, a suitable process for the purpose is the reverse suspension polymerization process.
[0072] The surface crosslinking agent solution can also include from 0% by weight to about 1% by weight, or from about 0.01% by weight to about 0.5% by weight based on the composition dry particulate superabsorbent polymer of a thermoplastic polymer. Examples of thermoplastic polymers include polyolefin, polyethylene, polyester, linear low density polyethylene (LLDPE), ethylene acrylic acid copolymer (EAA), ethylene-methyl ethyl methacrylate (EMA) copolymer, polypropylene (PP), male-bonded polypropylene, copolymer of ethylene vinyl acetane (EVA), polyester and blends of all polyolefin families, such as blends of PP, EVA, EMA, EEA, EBA, HDPE, MDPE, LDPE, LLDPE and / or VLDPE, can also be advantageously employed. The term polyolefin as used in this document is defined above. In particular aspects, malformed polypropylene is a preferred thermoplastic polymer for use in the present invention. A thermoplastic polymer can be functionalized to have additional benefits such as water solubility or dispersibility.
[0073] The heat treatment, which follows the coating treatment of the particulate superabsorbent polymer, can be carried out as follows. In general, the heat treatment is at a temperature of about 100 ° C to about 300 ° C. Lower temperatures are possible if highly reactive epoxide crosslinking agents are used. However, if an ethylene carbonate is used, then the heat treatment is suitably at a temperature of about 150 ° C to about 250 ° C. In this particular aspect, the treatment temperature depends on the expansion time and the type of ethylene carbonate. For example, at a temperature of around 150 ° C, heat treatment is carried out for an hour or more. In contrast, at a temperature of about 250 ° C, a few minutes (for example, from about 0.5 minutes to about 5 minutes) are sufficient to achieve the desired surface cross-linking properties. Heat treatment can be carried out in conventional dryers or ovens known in the art.
[0074] In addition to surface crosslinking, particulate superabsorbent polymeric compositions can be additionally treated on the surface with other chemical compositions. The particulate superabsorbent polymeric composition according to the invention comprises about 0.01% by weight to about 5% by weight based on the weight of the particulate superabsorbent composition of an aluminum salt applied to the surface of the particulate superabsorbent polymer in the in the form of an aqueous solution having a pH value of about 5.5 to about 8, or about 6 to about 7. Or, the particulate superabsorbent polymer composition comprises about 6% by weight at about 15 % by weight based on the weight of the particulate superabsorbent composition of an aqueous aluminum salt solution applied to the surface of the cross-linked particulate superabsorbent polymer, with the aqueous aluminum salt solution having a pH value of about 5.5 at about 8, or from about 6 to about 7. The aqueous solution of the aluminum salt may comprise an aluminum cation and a hydroxyl ion or an anion of a deprotonated organic hydroxyl acid. Examples of preferred organic acids are hydroxy monocarboxylic acids such as lactic acid, glycolic acid, gluconic acid or hydroxypropionic acid-3.
[0075] Additionally, a superabsorbent polymeric composition with significantly improved stability including resistance to damage control is obtained unexpectedly by coating the superabsorbent polymer with the aluminum salt solution that has an adjusted pH of about 5.5 to about from 8, or from about 6 to about 7 and appropriate concentration and amounts. The aqueous aluminum salt solution includes the reaction product of alkali hydroxide and aluminum sulfate or aluminum sulfate hydrate. In another embodiment, the aqueous aluminum salt solution includes the reaction product of sodium hydroxide and aluminum sulfate or aluminum sulfate hydrate. In yet another embodiment, the aqueous aluminum salt solution comprises an aluminum compound and an organic acid. The mixture of the aluminum compound with the organic acid (salt) can be acidic or basic. And the pH can be adjusted to the desired range with a basic or acidic material. Examples of basic pH adjustment materials include, but are not limited to, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate or sodium bicarbonate. Examples of acidic materials for pH adjustment include, but are not limited to, hydrochloric acid, sulfuric acid, methylsulfonic acid or carbon dioxide in water. Acid aluminum salts, such as aluminum chloride, aluminum sulfate, aluminum nitrate and polyaluminium chloride or basic aluminum salts, such as sodium aluminate, potassium aluminate and ammonium aluminate, can be used for the adjustment pH as well.
[0076] The aqueous aluminum salt solution can be added at various stages of the surface treatment of the particulate superabsorbent polymer. In one embodiment, the aqueous aluminum salt solution can be applied to the particulate superabsorbent polymer together with the surface crosslinker solution.
[0077] The aqueous aluminum salt solution can be added after the cross-linking step, which can be called post-treatment. In one embodiment, the superabsorbent polymer with a cross-linked surface and the aluminum salt are mixed using the medium well known to those skilled in the art. In particular, from about 6% by weight to about 15% by weight of an aqueous aluminum salt solution is applied to a particulate superabsorbent polymeric composition with a cross-linked surface.
[0078] The particulate superabsorbent polymer composition that has improved stability can include from about 0% by weight to about 5% by weight, or from about 0.001% by weight to about 3% by weight, or from about 0 , 01% by weight to about 2% by weight based on the weight of the dry particulate superabsorbent polymer composition of a cationic polymer. A cationic polymer as used herein refers to a polymer or mixture of polymers that comprises a functional group or groups that have the potential to become positively charged ions by ionization in an aqueous solution. Functional groups suitable for a cationic polymer include, but are not limited to, amino groups, imino groups, imido groups, primary, secondary or tertiary starch groups or quaternary ammonia groups. Examples of synthetic cationic polymers include the salts or partial salts of poly (vinyl amines), poly (allylamines) or poly (ethylene imine). Examples of cationic polymers with a natural base include chitin, chitosan and partially de-satetylated chitosan salts.
[0079] The particulate superabsorbent polymer composition that has improved stability can include from about 0% by weight to about 5% by weight, or from about 0.001% by weight to about 3% by weight, or from about 0 , 01% by weight to about 2% by weight based on the weight of the dry particulate superabsorbent polymer composition of water-insoluble inorganic powder. Examples of insoluble inorganic powders include silicon dioxide, silica, titanium dioxide, aluminum oxide, magnesium oxide, zinc oxide, talc, calcium phosphate, clays, diatomaceous earth, zeolites, bentonite, kaolin clays, activated hydrotalcite , etc. The insoluble inorganic powder additive can be a single compound or a mixture of compounds selected from the list above. Examples of silica include smoked silica, precipitated silica, silicon dioxide, silica acid and silicates. In some particular aspects, microscopic non-crystalline silicon dioxide is desirable. Products include SIPERNAT® 22S and AEROSIL® 200 available from Evonik Corporation, Parsippany, New Jersey. In some respects, the particle diameter of the inorganic powder can be 1,000 μm or less, such as 100 μm or less.
[0080] The particulate superabsorbent polymer composition that has improved stability may also include from 0% by weight to about 30% by weight, or from about 0.001% by weight to about 25% by weight, or from about 0, 01% by weight to about 20% by weight based on the weight of the dry particulate superabsorbent polymeric composition of water-soluble polymers, such as partially or completely hydrolyzed polyvinyl acetate, gum or gum derivatives, polyglycols or acrylic polyacids , preferably in polymerized form. The molecular weight of these polymers is not important since they are soluble in water. Preferred water-soluble polymers are gum and polyvinyl alcohol. The preferred content of such water-soluble polymers in the absorbent polymer according to the invention is 0 to 30% by weight, or 0 to 5% by weight, based on the total amount of the dry particulate superabsorbent polymer composition. Water-soluble polymers, preferably synthetic polymers, such as polyvinyl alcohols can also serve as a graft base for the monomers to be polymerized.
[0081] The particulate superabsorbent polymeric composition which has improved stability may also include from 0% by weight to about 5% by weight, or from about 0.001% by weight to about 3% by weight, or from about 0, 01% by weight to about 2% by weight based on the weight of the dry particulate superabsorbent polymeric composition, of anti-dust agents, such as hydrophilic and hydrophobic anti-dust agents such as those described in US Patent Documents No. 6,090,875 and 5,994. 440.
[0082] In some respects, other surface additives can optionally be used with the particulate superabsorbent polymer composition that has improved permeability stability, such as odor-binding substances, such as cyclodextrins, zeolites, organic salts and inorganic and similar materials; anti-pelleting additives, flow modifying agents, surfactants, viscosity modifiers and the like.
[0083] The particulate superabsorbent polymeric composition that has improved stability of the present invention can be, after the heat treatment step, treated with an aqueous solution, such as the aqueous solution of deprotonated organic acid salt, aluminum salt or water-soluble polymer such as polyethylene glycol. The treated particulate superabsorbent composition has a moisture content of about 3% by weight to about 15% by weight, or from about 4% by weight to about 12% by weight, or from 5% by weight to about 11%. % by weight based on the particulate superabsorbent polymeric composition.
[0084] The particulate superabsorbent polymeric composition which has improved stability according to the invention can be desirably prepared by various methods disclosed in the art, including the following methods and exemplified in the Examples. The particulate superabsorbent polymeric composition can be prepared continuously or discontinuously on a large scale in an industrial manner, the post-treatment being carried out according to the invention.
[0085] According to a method, the monomer is partially neutralized by adding an alkaline base such as sodium hydroxide to the monomer or by adding the monomer to an alkaline solution. Then, the partially neutralized monomer, such as acrylic acid, is converted to a gel by free radical polymerization in aqueous solution in the presence of crosslinking agents and any additional components and the gel is crushed, dried, ground and sieved to the size of desired particle, thus forming a particulate superabsorbent polymer. This polymerization can be carried out continuously or discontinuously.
[0086] For the present invention, the particle size of the high capacity superabsorbent polymeric composition is dependent on manufacturing processes, including grinding and sifting. It is well known to those skilled in the art that the particle size distribution of the particulate superabsorbent polymer looks like a normal distribution or a bell-shaped curve. It is also known that for various reasons, the normal distribution of the particle size distribution can be shifted in any direction.
[0087] According to another method for producing the particulate superabsorbent polymer, the reverse suspension and emulsion polymerization can also be used to prepare the products according to the invention. According to these processes, an aqueous and partially neutralized monomer solution, such as acrylic acid, is dispersed in an organic and hydrophobic solvent with the aid of protective colloids and / or emulsifiers and the polymerization is initiated by free radical initiators. The internal crosslinking agents can be dissolved in the monomeric solution and measured together with it or can be added separately and optionally during polymerization. The addition of a water-soluble polymer as the graft base optionally takes the place through the monomeric solution or by direct introduction into the oil phase. The water is then removed azeotropically from the mixture and the polymer is filtered and optionally dried. The internal crosslinking can be carried out by polymerization in a polyfunctional crosslinking agent dissolved in the monomeric solution and / or by the reaction of suitable crosslinking agents with functional groups of the polymer during the polymerization steps.
[0088] The particulate superabsorbent polymeric composition that has improved stability of the present invention exhibits certain characteristics or properties, as measured by the Free Dilatation Gel Bed Permeability (FSGBP), Centrifugal Holding Capacity (CRC), absorbance under load at about 6.2 kPa (0.9 psi) (0.9 psi AUL) and Compressibility. The FSGBP Test is a measure of the permeability of an expanded bed of the particulate superabsorbent polymer composition in terms of 10-8 cm2 (eg, separated from the absorbent structure) under a confining pressure after what is commonly called "free expansion". In this context, the term "free swelling" means that the particulate superabsorbent polymeric composition is allowed to swell without a swelling restriction charge by absorbing the Test solution as will be described.
[0089] Permeability is a measure of the effective connectivity of a porous structure, whether it be a fiber mat or a foam board or, in the case of this application, the particulate superabsorbent polymer and the particulate superabsorbent polymeric composition, generally called polymeric compositions superabsorbents partici- pated in this document, or SAP, and can be specified in terms of the fraction of empty space and the extent of connectivity of particulate superabsorbent polymeric compositions. Gel permeability is a property of the mass of particulate superabsorbent polymer compositions as a whole and is related to the particle size distribution, particle shape, open pore connectivity, shear modulus and surface modification of the swollen gel. In practical terms, the permeability of the particulate superabsorbent polymeric composition is a measure of how fast the liquid flows through the mass of swollen particles. Low permeability indicates that the liquid cannot flow readily through the particulate superabsorbent polymeric compositions, which is generally called a gel blocker, and that any forced flow of liquid (such as a second urine application during diapering) needs to do an alternative path (for example, diaper leak).
[0090] The Centrifugal Retention Capacity Test (CRC) measures the capacity of the particulate polymeric superabsorbent composition to retain liquid in it after being saturated and subjected to centrifugation under controlled conditions. The resulting holding capacity is stated in grams of liquid retained per gram of the sample weight (g / g).
[0091] The Absorbance Under Load Test (AUL) measures the ability of the particles of the particulate superabsorbent polymer composition to absorb 0.9 weight percent of the sodium chloride solution in distilled water at room temperature (Test solution) while the material is under a load of 6.2 kPa (0.9 psi).
[0092] The Compressibility Test measures the relative volume change of the particulate superabsorbent polymeric composition as a response to a pressure change and is performed on the original particulate superabsorbent polymeric composition or shortly after the particulate superabsorbent polymeric composition is manufactured.
[0093] The Processing Test measures the stability of the performance properties of the particulate superabsorbent polymeric composition against external forces applied to the particulate superabsorbent polymeric composition prior to or subsequent to the application of the Processing Test. The test conditions are selected to simulate the process of reducing the volume of absorbent articles.
[0094] All Centrifugal Retention Capacity, Absorbance Under Load and Gel Bed Permeability values set forth in this document must be understood to be determined by the Centrifugal Retention Capacity Test, Absorbance Under Load Test, Bed Permeability Test Free Dilatation Gel and Compressibility Test as provided in this document.
[0095] The particulate superabsorbent polymer composition that has improved stability produced by a process of the present invention can have a centrifugal retention capacity of about 25 g / g to about 40 g / g, or from about 27 to about 35 g / g an absorbance under load at 6.2 kPa (0.9 psi) before submitting the treated particulate superabsorbent composition to the Processing Test of about 15 g / g to about 21 g / g, or about 16 g / g about 20 g / g; an absorbance under load at 6.2 kPa (0.9 psi) subsequent to subjecting the particulate superabsorbent polymeric composition to the Processing Test of about 14 g / g to about 21 g / g, or about 14 g / g to about 20 g / g; a compressibility of about 1.30 mm2 / N to about 4 mm2 / N, or from about 1.30 mm2 / N to about 3.5 mm2 / N, a permeability stability index of about 0.60 to about 0.99, or about 0.70 to about 0.97 and an original Free Dilatation Gel Bed Permeability (FSGBP) of about 30 x 10-8 cm2 to about 200 x 10-8 cm2 before subjecting the treated particulate superabsorbent composition to a Processing Test, the particulate superabsorbent polymer composition has a permeability stability index of about 0.60 to about 0.99, or from about 0.70 to about 0 , 97. In addition, the particulate superabsorbent polymer composition has a pressure absorbance (AAP) of 4.8 kPa for the physiological saline solution that is no more than 21 g / g, or 15 g / g to 20 g / g. In addition, the particulate superabsorbent polymer composition that has improved stability can have an increase in centrifugal retention capacity of at least 2 g / g, or 2 g / g to about 50 g / g, or from 2 g / g to about 30 g / g.
[0096] The particulate superabsorbent polymeric composition according to the present invention generally has a particle size of about 150 μm to about 850 μm and comprises about 1 to about 40% by weight of the particulate superabsorbent polymer composition which has a particle size of more than 600 μm or from about 1 to about 35% by weight of the particulate superabsorbent polymer composition which has a particle size of more than 600 μm, or about 12% by weight at about 25% by weight of the particulate superabsorbent polymeric composition which has a particle size of more than 600 μm, or less than about 15% by weight of the particulate superabsorbent polymeric composition which has a particle size of more than than 600 μm and as specified by the standard sieve rating. In addition, the particulate superabsorbent polymeric composition according to the present invention can have an average weight particle diameter (D50) as specified by the standard sieve rating of about 300 to about 400 μm, or about 350 to about 400 μm, or from about 360 to about 400 μm, or from about 370 to about 400 μm.
[0097] The particulate superabsorbent polymeric compositions according to the present invention can be used in various absorbent articles which include sanitary towels, diapers or wound protectors and they have the property to quickly absorb large amounts of menstrual blood, urine or others body fluids. Since the agents according to the invention retain the absorbed liquids even under pressure and are also capable of additionally distributing liquid within the construction in the expanded state, they are more desirably employed in higher concentrations, with respect to the hydrophilic fiber material, such as as soft materials, when compared to conventional superabsorbent compositions. They are also suitable for use as a homogeneous superabsorbent layer with no softness content within the diaper construction, as a result of which particularly thin articles are possible. Polymers are best suited for use in hygiene items (eg incontinence products) for adults.
[0098] The polymers according to the invention are also used in absorbent articles that are suitable for additional uses. In particular, the polymers of this invention can be used in absorbent compositions for absorbents for water or aqueous liquids, preferably in constructions for absorbing bodily fluids in structures of the type with or without foam, in packaging materials, in constructions for growing plants, as soil improvement agents or as carriers of active compost. For this, they are processed in a network by mixing with paper or lint or synthetic fibers or by distributing the superabsorbent polymers among substrates of paper, lint or non-sewn fabrics or in processing in carrier materials. TEST PROCEDURES
[0099] It is observed that all property measurements are made before the Processing Test, unless otherwise specified. Vortex Test
[00100] The Vortex Test measures the amount of time in seconds required for 2 grams of an SAP to close a Vortex created by shaking 50 milliliters of saline at 600 revolutions per minute on a magnetic stirring plate. The time it takes for the Vortex to close is an indication of the SAP's free expansion absorption rate. EQUIPMENT AND MATERIALS 1. Schott Duran 100 mL beaker and 50 mL graduated cylinder. 2. Programmable magnetic stir plate capable of delivering 600 revolutions per minute (such as those commercially available from PMC Industries under the Dataplate® Model # 721 brand). 3. Magnetic stirring bar without rings, 7.9 mm times 32 mm, covered with Teflon® (such as those commercially available from Baxter Diagnostics, with the S / PRIM brand single package with rounded stirring bars with ring removable pivot). 4. Stopwatch 5. Scale, with an error margin of +/- 0.01 g 6. Saline solution, 0.87% w / w of Blood Bank Saline made available by Baxter Diagnostics (considered for the purposes of this application as being equivalent to 0.9% by weight of saline) 7. Weighing paper 8. Room with standard atmospheric condition: Temp = 23 ° C + / 1 ° C. and Relative Humidity = 50% +/- 2%. TEST PROCEDURE 1. Measure 50 mL +/- 0.01 mL of saline in the 100 mL beaker. 2. Place the magnetic stir bar in the beaker. 3. Set the magnetic stir plate to 600 revolutions per minute. 4. Place the beaker in the center of the magnetic stirring plate so that the magnetic stirring bar is activated. The bottom of the Vortex should be near the top of the stir bar. 5. Weigh 2 g +/- 0.01 g of SAP to be tested on the weighing paper. NOTE: SAP is tested as received (ie, as it would be in an absorbent composite such as those described in this document). No screening of a specific particle size is done, although the particle size is known to have an effect on this Test. 6. While the saline is being stirred, quickly pour the SAP to be tested in the saline and start the timer. The SAP to be tested must be added to the saline solution between the center of the vortex and the side of the beaker. 7. Stop the timer when the saline surface becomes flat and record the time. 8. Time, recorded in seconds, is reported as Vortex Time. CENTRIFUGAL RETENTION CAPACITY TEST (CRC)
[00101] The CRC Test measures the ability of the particulate superabsorbent polymer composition to retain liquid in it after being saturated and subjected to centrifugation under controlled conditions. The resulting holding capacity is reported in grams of liquid retained per gram of sample weight, (g / g). The CRC Test can be performed before or after submitting the particulate superabsorbent polymeric composition to a Processing Test, as established in this document. The sample to be tested is prepared with particles that are pre-examined through a USA standard 30 mesh screen and retained on a USA standard 50 mesh screen. As a result, the sample of particulate superabsorbent polymeric composition comprises particles ranging in size from about 300 to about 600 microns. The particles can be pre-examined manually or automatically.
[00102] Retention capacity is measured by placing about 0.20 grams of the sample of the pre-screened particulate superabsorbent polymer composition in a water-permeable bag that will contain the sample while allowing a Test solution (0.9 per percent by weight of sodium chloride in distilled water) is freely absorbed by the sample. A heat sealable tea bag material, such as those available from Dexter Corporation (which is available through Locks, Connecticut, USA) with model designation of the 1234T heat sealable filter paper that works well for most applications. The pouch is formed by folding a sample of 12.7 centimeters (5 inches) by 7.6 centimeters (3 inches) of the material in the material pouch and heat-sealing two of the open edges to form a 6.3-inch rectangular package centimeter (2.5 inches) by 7.6 centimeters (3 inches). Heat seals are about 0.64 centimeters (0.25 inches) inside the edge of the material. After the sample is placed in the package, the remaining open edge of the package is also heat sealed. Empty bags are also produced to serve as controls. Three samples are prepared for each particulate superabsorbent polymer composition to be tested.
[00103] The sealed bags are submerged in a pan containing the Test solution at about 23 ° C, to confirm that the bags are kept underneath until they are completely wet. After wetting, the samples of the particulate superabsorbent polymer composition remain in the solution for about 30 minutes, after which time they are removed from the solution and temporarily rested on a flat non-absorbent surface.
[00104] The wet bags are then placed in the basket and the wet bags are separated from each other and are placed on the outer circumferential edge of the basket, the basket having a suitable centrifuge capable of subjecting the samples to a g force about 350. A suitable centrifuge is CLAY ADAMS DYNAC II, model # 0103, which features a water collection basket, a digital rpm meter and a machined drain basket adapted to hold and drain samples from the flat bag. When centrifuging multiple samples, the samples are placed in opposite positions within the centrifuge to balance the basket when rotating. The bags (which includes the empty wet bags) are centrifuged at about 1,600 rpm (for example, to achieve a target g force of about 350 g of force with a range of about 240 to about 360 g of force) for 3 minutes. The G-force is defined as a unit of inertial force in a body that is subjected to rapid acceleration or gravity, equal to 9.7 meters / sec2 (32 feet / sec2) at sea level. The bags are removed and weighed, and the empty bags (controls) are weighed, first, then the bags containing the samples of the particulate superabsorbent polymer composition. The amount of solution retained by the sample of the particulate superabsorbent polymer composition, considering the solution retained by the bag itself, is the centrifugal retention capacity (CRC) of the superabsorbent polymer, expressed in grams of fluid per gram of the superabsorbent polymer. - sell. More particularly, the holding capacity is determined by the following equation: CRC = [sample bag after centrifugation - empty bag after centrifugation - dry sample weight] / dry sample weight
[00105] The three samples are tested and the results are averaged to determine the CRC of the particulate superabsorbent polymer composition.
[00106] CRC (ta, 0.5 h) is measured with a Test temperature of about 23 ° C (room temperature) and a Test time of 0.5 hour.
[00107] CRC (tc, 5 h) is measured with a Test temperature of about 37 ° C (body temperature) and a Test time of 5 hours. TEST TO INCREASE THE CENTRAL LEAKAGE CAPACITY (CRCI)
[00108] The Centrifugal Retention Capacity Increase Test (CRCI) measures the increase in CRC that occurs and is calculated as the difference between the second CRC Test and the first CRC (ta, 0.5 h) Test and is determined by the following equation: Increase in CRC = CRC (tc, 5 h) .- (CRC (ta, 0.5 h). FREE DILATATION GEL BED PERMEABILITY TEST (FSGBP)
[00109] As used in this document, the Free Dilatation Gel Bed Permeability Test also called the Gel Bed Permeability Expansion Pressure Test under 0 kPa (0 psi) (FSGBP), determines the permeability of an expanded bed of gel particles (for example, such as the particulate superabsorbent polymer composition, or the particulate superabsorbent polymer before surface treatment), under what is commonly called "free expansion" conditions . The term "free swelling" means that the gel particles are allowed to swell without a restrictive load when absorbing the Test solution as will be described. An apparatus suitable for conducting a Gel Bed Permeability Test is shown in Figures 1, 2 and 3 and is usually indicated by 500. The assembly of the Test apparatus 528 comprises a sample container, generally indicated by 530 and a plunger, generally indicated by 536. The plunger comprises a shaft 538 which has a cylinder hole drilled downwards in the longitudinal geometric axis and a head 550 positioned at the bottom of the shaft. The shaft hole 562 has a diameter of about 16 mm. The plunger head is attached to the shaft, just as by adhesion. Twelve holes 544 are drilled on the radial axis of the axle, three positioned every 90 cranes that have diameters of about 6.4 mm. The 538 shaft is machined by a LEXAN shank or equivalent material and has an outside diameter of about 2.2 cm and an internal diameter of about 16 mm.
[00110] The plunger head 550 has a concentric inner ring with seven holes 560 and an outer ring with 14 holes 554, all holes having a diameter of about 8.8 mm as well as a hole of about 16 mm aligned to the axis. The plunger head 550 is machined by the LEXAN rod or equivalent material and has a height of approximately 16 mm and a diameter with a size that allows it to fit inside the cylinder 534 with minimum wall spacing, but still slide freely. The total length of the plunger head 550 and shaft 538 is about 8.25 cm, but can be machined at the top of the shaft to obtain the mass of the plunger 536 desired. The plunger 536 comprises a screen 564 covered by 100 mesh stainless steel which is biaxially stretched and attached to the lower end of the plunger 536. The screen is connected to the head of the plunger 550 by the use of an appropriate solvent that causes the screen is adhered securely to the plunger head 550. Care must be taken to avoid excess solvent migrating to the open portions of the screen and reducing the open area for liquid flow. Acrylic adhesive, Weld-On # 4, from IPS Corporation (which is marketed in Gardena, California, USA) is a suitable adhesive.
[00111] Sample container 530 comprises a cylinder 534 and a screen 566 covered by 400 mesh stainless steel which is biaxially stretched by tension and attached to the lower end of cylinder 534. The screen is connected to the cylinder by the use of an appropriate solvent which makes the screen adhere securely to the cylinder. Care must be taken to avoid excess solvent that migrates to open portions of the screen and reduces the open area of liquid flow. Acrylic adhesive, Weld-On # 4, from IPS Corporation is a suitable adhesive. A sample of gel particle indicated as 568 in Figure 2, is held on screen 566 inside cylinder 534 during the Test.
[00112] Cylinder 534 can be drilled from a transparent LEXAN rod or equivalent material, or it can be cut from LEXAN tubing or equivalent material and has an internal diameter of about 6 cm (for example, a cross-sectional area of about 28.27 cm2), a wall thickness of about 0.5 cm and a height of approximately 7.95 cm. A stirrup is machined to the outside diameter of cylinder 534 so that a region 534a with an outside diameter of 66 mm exists for the bottom 31 mm of cylinder 534. An O-ring 540 which adjusts the diameter of region 534a can be placed at the top of the stirrup.
[00113] The annular weight 548 has an opposed hole drilled about 2.2 cm in diameter and 1.3 cm deep so that it slides freely into the 538 axis. The annular weight also has a hole through 548a of about 16 mm. The ring weight 548 may be made of stainless steel or other suitable corrosion resistant material in the presence of the Test solution, which is 0.9 weight percent sodium chloride solution in distilled water. The combined weight of the plunger 536 and annular weight 548 is approximately equal to 596 grams (g), which corresponds to a pressure applied to the sample 568 of about 210 kgf / m2 (0.3 pounds per square inch - psi) or about 20.7 dynes / cm2 (2.07 kPa), in a sample area of about 28.27 cm2.
[00114] When the Test solution flows through the Test apparatus during the Test as described below, the sample container 530 generally rests in a 600 dam. The purpose of the dam is to divert the overflowing liquid from the top of the sample container 530 and divert the overflowing liquid to a separate collection device 601. The dam can be positioned above a scale 602 with a beaker 603 that rests on it to collect saline solution that passes through the swollen sample 568.
[00115] To conduct the Gel Bed Permeability Test under "free expansion" conditions, the plunger 536, with the weight 548 resting on it, is placed in an empty sample container 530 and the height of the upper part of the weight 548 at the bottom of the sample container 530 is measured using a suitable meter with a margin of error of 0.01 mm. The force that the thickness gauge applies during measurement should be as low as possible, preferably less than about 0.74 Newtons. It is important to measure the height of each container 530, plunger 536 and weight 548 of empty sample in combination and keep track of which plunger 536 and weight 548 are used when using the multiple tester. The same plunger 536 and weight 548 should be used to measure when sample 568 was later dilated after saturation. It is also desirable that the base on which the sample cup 530 is resting is flat and the upper surface of the weight 548 is parallel to the lower surface of the sample cup 530.
[00116] The sample to be tested is prepared from the particulate superabsorbent polymeric composition, which is pre-screened through a USA standard 30 mesh screen and retained on a USA standard 50 mesh screen. As a result, the Test sample comprises particles ranging in size from about 300 to about 600 microns. The particles of the superabsorbent polymer can be pre-examined with, for example, a RO-TAP Model B Mechanical Sieve Shaker provided by W.S. Tyler, Inc., Mentor Ohio. Sifting is conducted for 10 minutes. Approximately 2.0 grams of the sample are placed in the 530 sample container and spread evenly on the bottom of the sample container. The container, with 2.0 grams of the sample in it, without the plunger 536 and the weight 548 in it, is then submerged in 0.9% saline for a period of about 60 minutes to saturate the sample and allow the sample to expand free of any restrictive load. During saturation, sample cup 530 is placed on a mesh located in the liquid reservoir so that sample cup 530 is raised slightly above the bottom of the liquid reservoir. The mesh does not show the flow of saline into the 530 sample cup. A suitable mesh can be obtained as part number 7.308 from Eagle Supply and Plastic, which has a store in Appleton, Wisconsin, USA. Saline does not completely cover the particles of the superabsorbent polymeric composition, as would be evident by a perfectly flat saline surface in the Test cell. In addition, the saline depth is not allowed to decrease so that the surface inside the cell is defined only dilated superabsorbent, in place of the saline.
[00117] At the end of this period, the plunger assembly 536 and weight 548 is placed in the saturated sample 568 in the sample container 530 and then the sample container 530, the plunger 536, the weight 548 and the sample 568 are removed from the solution . After removing a before starting to measure, the sample container 530, the plunger 536, the weight 548 and the sample 568 should remain resting for about 30 seconds on a non-deformable plate of wide, flat grid of uniform thickness. The thickness of the saturated sample 568 is determined by re-measuring the height from the top of the weight 548 to the bottom of the sample container 530, using the same thickness gauge previously used as long as the zero point has not changed since the initial height measurement. . Sample container 530, plunger 536, weight 548 and sample 568 can be placed on a non-deformable plate of wide, flat grid of uniform thickness that will provide drainage. The plate has an overall dimension of 7.6 cm by 7.6 cm, and each grid has a cell size of 1.59 cm long by 1.59 cm wide by 1.12 cm deep. A wide, flat grid non-deformable plate material is a parabolic diffuser panel, catalog number 1624K27, available from McMaster Carr Supply Company, which has a store in Chicago, Illinois, USA, which can then be cut to the appropriate dimensions. This wide, flat, non-deformable plate must also be present when measuring the height of the initial empty assembly. The height measurement should be made right after the thickness gauge is engaged. The height measurement obtained from the measurement of the empty sample container 530, the plunger 536 and the weight 548, is subtracted from the height measurement obtained after sample saturation 568. The resulting value is the thickness or height "H" of the dilated sample.
[00118] The permeability measurement is initiated by delivering a flow of 0.9% saline into sample container 530 with saturated sample 568, plunger 536 and weight 548 inside. The flow rate of the Test solution into the container is adjusted to cause saline to overflow from the top of the cylinder 534 which results in a consistent head pressure equal to the height of the sample container 530. The Test solution can be added by any suitable means that is sufficient to guarantee a small but consistent amount of overflow from the top of the cylinder, such as a 604 metering pump. The overflowing liquid is diverted to a separate collection device 601. The amount of the solution passes through sample 568 versus time is measured gravimetrically using the 602 scale and the 603 beaker. 602 scale data points are collected every second for at least sixty seconds once the overflow has started. Data collection can be done manually or with data collection software. The flow rate, Q, across the swollen sample 568 is determined in units of grams / second (g / s) by a linear minimum square adjustment of the fluid that passes through the sample 568 (in grams) versus time (in seconds) .
[00119] The permeability in cm2 is obtained by the following equation: K = [Q * H * μ] / [A * p * P] in which K = Permeability (cm2), Q = flow rate (g / sec), H = height of dilated sample (cm), μ = liquid viscosity (poise) (approximately one centipoise for the Test solution used with this Test), A = cross-sectional area for the liquid flow (28,27 cm2 for the sample container used with this Test), p = liquid density (g / cm3) (approximately one g / cm3, for the Test solution used with this Test) and P = hydrostatic pressure (dia / cm2 ) (normally close to 7,797 dynes / cm2). The hydrostatic pressure is calculated from P = p * g * h, where p = liquid density (g / cm3), g = gravitational acceleration, nominally 981 cm / sec2 and h = fluid height, for example, 7, 95 cm for the Gel Bed Permeability Test described in this document.
[00120] A minimum of two samples are tested and the results are averaged to determine the gel bed permeability of the sample of the particulate superabsorbent polymer composition.
[00121] The FSGBP can be measured as described in this document before submitting a particulate superabsorbent polymeric composition to a Processing Test as described in this document. This FSGBP value can be called the "original" FSGBP of the particulate superabsorbent polymer composition. FSGBP can additionally be measured subsequent to subjecting the particulate superabsorbent polymeric composition to the Processing Test. Such FSGBP value can be called "post-processing" FSGBP. In comparison to the original FSGBP of a particulate superabsorbent polymeric composition with the post-processing FSGBP of the particulate superabsorbent polymeric composition can be used as a measure of the stability of the composition. It should be noted that all "original" and "post-processing" FSGBP values reported in this document were measured using a sample of pre-examined particles with 300 to 600 μm. ABSORBANCE TEST UNDER LOAD (AUL (6.2 kPa (0.9 psi))
[00122] The Absorbance Under Load Test (AUL) measures the ability of the particulate superabsorbent polymer composition to absorb 0.9 weight percent of the sodium chloride solution in distilled water at room temperature (test solution) while the material is under load of 6.2 kPa (0.9 psi). The device for testing AUL consists of: • An AUL assembly that includes a cylinder, a piston of 4.4 g and a standard weight of 217 grams. The components of this assembly are described in more detail below. • A square plastic tray with a flat bottom that is sufficiently wide to allow the glass frit to rest on the bottom without coming into contact with the walls of the tray. A plastic tray that is 22.9 cm x 22.9 cm (9 "by 9"), with a depth of 1.3 cm to 2.5 cm (0.5 to 1 ") is commonly used for the method of • A 9 cm diameter sintered glass frit with a "C" polarity (25 to 50 microns) This frit is prepared in advance by balancing saline (0.9% sodium chloride in desiccated water) -tied, by weight.) In addition to being washed with at least two portions of fresh saline, the frit must be immersed in saline for at least 12 hours before AUL measurements. • Filter paper circles with a diameter of 1.9 centimeters Whatman Grade • A supply of saline (0.9% sodium chloride in distilled water, by weight).
[00123] With reference to Figure 4, the cylinder 412 of the AUL 400 assembly used to contain the particulate superabsorbent polymer composition 410 is produced with 2.54 cm (one inch) of inner diameter of lightly machined thermoplastic tubing to ensure concentricity. After machining, a fabric 414 of 400 mesh stainless steel wire is attached to the bottom of the cylinder 412 by heating the steel wire fabric 414 in a flame until it redens and after that the cylinder 412 is held in the steel wire fabric until it cools. A soldering iron can be used to touch the seal if unsuccessful or if it breaks. Care must be taken to maintain a smooth, flat bottom and not to bend the inside of cylinder 412.
[00124] The 4.4 g (416) piston is produced from a solid material 2.5 cm (1 inch) in diameter (for example, PLEXIGLAS®) and is machined to precisely adjust without holding the 412 cylinder.
[00125] A standard weight of 317 grams 418 is used to provide a restrictive load of 6.21 kPa (62,053 dynes / cm2, about 0.9 psi). The weight is a 2.5 mm (1 inch) cylindrical stainless steel weight that is machined to fit precisely without attaching to the cylinder.
[00126] Unless otherwise specified, a sample 410 that corresponds to a layer of at least about 300 gsm (0.16 g) of the particles of the superabsorbent polymeric composition is used to test the AUL. Sample 410 is taken from the particles of the superabsorbent polymeric composition that are pre-examined through the USA standard 30 mesh and retained in the USA standard 50 mesh. The particles of the superabsorbent polymeric composition can be pre-examined, for example, with a RO-TAP® Model B Mechanical Sieve Shaker available from W. S. Tyler, Inc., Mentor Ohio. The screening is conducted for about 10 minutes.
[00127] The inside of cylinder 412 is dried with an antistatic fabric before placing the particles of the superabsorbent polymer composition 410 in cylinder 412.
[00128] The desired amount of the sample of the sieved particulate superabsorbent polymer composition 410 (about 0.16 g) is weighed on a weighing paper and distributed evenly on the yarn fabric 414 at the bottom of cylinder 412. The weight of the particulate superabsorbent polymer composition at the bottom of the cylinder is recorded as "SA", for use in calculating the AUL described below. Care must be taken to ensure that no particulate superabsorbent polymeric composition is adhered to the cylinder wall. After carefully placing the 4.4 g piston 412 and weight 317 g 418 into the particles of the superabsorbent polymer composition 410 in the cylinder 412, the AUL 400 assembly that includes the cylinder, piston, weight and particles of the particulate superabsorbent polymer composition is weighed and the weight is recorded as "A" weight.
[00129] A sintered 424 glass frit (described above) is placed on plastic tray 420, with saline 422 added at a level equal to that of the top surface of glass frit 424. Only one circle of filter paper 426 is placed smoothly on the glass frit 424 and the assembly of AUL 400 with the particulate superabsorbent polymer composition 410 is then placed on top of filter paper 426. The assembly of AUL 400 is then allowed to remain on top of filter paper 426 by a one hour test period, paying attention to keeping the saline level in the tray constant. At the end of an hour of testing, the AUL device is then weighed with this value registered as "B" weight.
[00130] AUL ((6.2 kPa) 0.9 psi) is calculated as follows: AUL ((6.2 kPa) 0.9 psi) = (BA) / SA where A = Weight of the unit of AUL with dry SAP B = Weight of AUL unit with SAP after 60 minutes of absorption SA = Weight of current SAP
[00131] A minimum of two Tests is performed and the results are averaged to determine the AUL value under 6.2 kPa (0.9 psi) of load. The samples of the particulate superabsorbent polymeric composition are tested at about 23 ° C and about 50% relative humidity. ABSORBANCE AGAINST PRESSURE [AAP ((4.83 kPa) 0.7 psi)]
[00132] A standard 400 mesh sieve made of stainless steel (38 μm size mesh) was cast at the bottom of a support cylinder made of plastic with an internal diameter of 60 mm and 0.9000 g of water-absorbent resin or water absorber was evenly spread on the sieve. A piston with an external diameter slightly less than 60 mm, with its own size to fit inside the support cylinder without spacing, but with a free vertical path inside the prepared cylinder. The piston has been adjusted in such a way that a load of 4.83 kPa (0.7 psi) can be applied evenly to the water-absorbent or water-absorbent resin. The piston and charge were placed in that order on the water-absorbent or water-absorbent resin and the total mass Wa (g) of this measuring device was measured. Then, a glass filter that has a diameter of 90 mm (produced by Sougo Rikagaku Grasu Seisakusho Co., Ltd .; pore diameter from 100 μm to 120 μm) was placed inside a Petri dish that has a diameter 150 mm and each solution was added at the level of the upper surface of the glass filter.
[00133] In the glass filter, a piece of filter paper, circles of filter paper of diameter 1.9 cm Whatman Grade, was placed to completely wet the filter paper and an excess of solution was removed.
[00134] The measuring device was then placed on the wet filter paper to absorb the solution that came into contact under pressure. After 1 hour, the measuring device was filtered and a weight Wb (g) of the measuring device was measured. From the values of Wa and Wb measured in this way, an absorbance against pressure (g / g) was calculated using the following formula: AAP (0.7) (g / g) = (Wb (g) - Wa (g)) / (0.9 g water-absorbent resin) HUMIDITY TEST
[00135] The amount of water content, measured as "% moisture" can be measured as follows: 1) Weigh 5.0 grams of the superabsorbent polymeric composition (SAP) precisely in a pre-weighed aluminum weighing pan; 2) Place the SAP and the pan in a standard laboratory oven preheated to 105 ° C for 3 hours; 3) Re-move and re-weigh the pan and contents and 4) Calculate the moisture percentage using the following formula:% Humidity = {((pan% by weight + initial SAP weight) - (dry SAP & pan weight) )) * 100} / initial SAP weight COMPRESSIBILITY TEST
[00136] The Compressibility Test measures the relative volume change of the particulate superabsorbent polymer composition as a response to a pressure change. The Test is conducted on a Zwick Tractor / Zwicki 1120 Compression Test. A sample of the superabsorbent polymeric composition is placed in a test cell of a thick-walled cylinder closed at the bottom and fitted at the top with a movable piston. The cylinder is 50 mm in diameter and 1 cm in depth. The piston moves at a speed of 0.2 mm / min. The normal force starts to increase when the piston touches the sample surface. The test is completed when the normal force reaches 90 N. The sample heights at the normal forces of 0 N and 90 N are automatically registered by the computer that is connected to the Zwick Tensioner / Compression Test. Compressibility = (initial height - final height) / (initial height) x (piston surface area) / (maximum normal force) PROCESSING TEST
[00137] The Processing Test measures the stability of the performance properties of the superabsorbent polymeric composition against external forces. The test conditions are selected to simulate the process of reducing the volume of absorbent articles. 40 grams of a sample of a particulate superabsorbent polymeric composition is distributed through a US standard 8.3 cm (8 inch) 18 mesh screen on a piece of chip board (dimension 22.5 "x 17.25) "x 0.03", commercially available from Central Wisconsin Paper located in Wausau, WI, USA) to form a 8.3 cm (eight inch) diameter circle. Another piece of chip board is then placed on top of the sample to form a chip board sandwich as a chip board sample. The sandwich is then placed through a two-roller calender press (BF Perkins serial number H8617-67) set at 80.85 kgf / cm2 (1,150 pounds) per square inch) of hydraulic pressure and a speed of 20 rpm. The processed sample is then removed from the chip board. CRC, AUL and FSGBP are then determined for the original and processed samples. The permeability stability index is used as the composition stability indicator superabsorbent polymeric ion. The same is calculated as follows: Permeability Stability Index = (GBP of the processed sample) / (GBP of the original sample). EXAMPLES
[00138] The following SAP A, B, A1 and GJ pre-products, Neutralized Aluminum Salts from C to F, Comparative Examples 1 to 5 and Examples 1 to 18 are provided to illustrate the inventions of the products o which includes particulate superabsorbent polymeric composition and processes for producing the particulate superabsorbent polymeric composition as set forth in the claims and is not limited to the scope of the claims. Unless otherwise stated in other parts and percentages it is based on the dry particulate superabsorbent polymer composition. SAP A. PRE-PRODUCT
[00139] A superabsorbent polymer can be produced as follows. In a polyethylene vessel equipped with a stirrer and cooling coils, 2.0 kg of 50% NaOH and 3.32 kg of distilled water were added and cooled to 20 ° C. 0.8 kg of glacial acrylic acid was added to the caustic solution and the solution was cooled again to 20 ° C. 4.8 g of polyethylene glycol monoalyl ether acrylate, 4.8 g of SARTOMER® 454 ethoxylated trimethylol propane triacrylate product and 1.6 kg of glacial acrylic acid were added to the first solution, followed by cooling to 4 to 6 ° C. Nitrogen was foamed through the monomer solution for about 5 minutes. The monomeric solution was then discharged into a rectangular tray. 80 g of 1% by weight of H2O2 in aqueous solution, 120 g of 2% by weight of aqueous sodium persulfate solution and 72 g of 0.5% by weight of aqueous sodium erythorbate solution were added to the modified solution. to initiate the polymerization reaction. The stirrer was stopped and the indicated monomer was allowed to polymerize for 20 minutes.
[00140] A particulate superabsorbent polymer can be prepared as follows. The resulting hydrogel was sliced and blasted with a commercial Hobart 4M6 extruder then dried by a forced air oven Procter & Schwartz Model 062 at 175 ° C for 12 minutes with upward flow and 6 minutes with downward air flow in a perforated metal tray 50 centimeters X 100 centimeters (20 inches x 40 inches) for a final product moisture level of less than 5% by weight. The dry material was coarsely ground in a Prodeva Model 315-S shredder, ground in an MPI 666-F three-stage roller grinder and sieved with a Minox MTS 600DS3V to remove particles larger than 850 μm and smaller than 150 μm. The obtained product A contained 4.0% moisture. SAP B PRE-PRODUCT
[00141] A superabsorbent polymer can be produced as follows. In a polyethylene vessel equipped with a stirrer and cooling coils, 1.9 kg of 50% NaOH and 3.34 kg of distilled water were added and cooled to 20 ° C. 0.83 kg of glacial acrylic acid was then added to the caustic solution and the solution was cooled again to 20 ° C. 4.46 g of polyethylene glycol monoalyl ether acrylate, 4.46 g of trimethylol propane ethoxylated triacrylate product SAR-TOMER® 454 and 1.65 kg of glacial acrylic acid were added to the first solution, followed by a 4-hour refrigeration. at 6 ° C. Nitrogen was foamed through the monomer solution for about 5 minutes. The monomeric solution was then discharged into a rectangular tray. 80 g of 1% by weight of H202 in aqueous solution, 120 g of 2% by weight of aqueous sodium persulfate solution and 72 g of 0.5% by weight of aqueous sodium erythorbate solution was added to the monomeric solution for initiate the polymerization reaction. The stirrer was stopped and the initiated monomer was allowed to polymerize for 20 minutes.
[00142] A particulate superabsorbent polymer can be prepared as follows. The resulting hydrogel was sliced and extruded with a commercial Hobart 4M6 extruder, then dried in a forced air force Procter & Schwartz Model 062 at 175 ° C for 12 minutes with upward flow and 6 minutes with downward air flow in a tray perforated metal measuring 50 cm x 100 cm (20 inches x 40 inches) to a final product moisture level of less than 5% by weight. The dry material was coarsely ground in a Prodeva Model 315-S shredder, ground in an MPI 666-F three-stage roller grinder and sieved with Minox MTS 600DS3V to remove particles larger than 850 μm and smaller than 150 μm . Pre-product B obtained contained 4.3% moisture. SAP A1 PRE-PRODUCT
[00143] A superabsorbent polymer can be produced as follows. In a polyethylene vessel equipped with a stirrer and cooling coils, 2.0 kg of 50% NaOH and 3.32 kg of distilled water were added and cooled to 20 ° C. 0.8 kg of glacial acrylic acid was then added to the caustic solution and the solution was cooled again to 20 ° C. 4.8g of polyethylene glycol of monoaliether acrylate, 4.8g of trimethylol propane triacrylate ethoxylated SAR-TOMER ® 454 and 1.6kg of glacial acrylic acid were added to the first solution, followed by cooling from 4 to 6 ° C . Nitrogen was foamed through the monomer solution for about 5 minutes. The monomeric solution was then discharged into a rectangular tray. 80 g of 1% by weight of H2O2 in aqueous solution, 120 g of 2% by weight of aqueous sodium persulfate solution and 72 g of 0.5% by weight of aqueous sodium erythorbate solution were added to the monomeric solution for initiate the polymerization reaction. The stirrer was stopped and the initiated monomer was allowed to polymerize for 20 minutes.
[00144] A particulate superabsorbent polymer can be prepared as follows. The resulting hydrogel was sliced and extruded with a commercial Hobart 4M6 extruder, then dried in a forced air oven Procter & Schwartz Model 062 at 175 ° C for 12 minutes with upward flow and 6 minutes with downward air flow in a tray perforated metal of 50 cm x 100 cm (20 inches x 40 inches) at a final product moisture level of less than 5% by weight. The dry material was coarsely ground in a Prodeva Model 315-S crusher, ground in a MPI 666-F three-stage roller mill and sieved with a Minox MTS 600DS3V to remove particles larger than 700 μm and smaller than 150 μm. The pre-product A1 obtained contained 12% of particles larger than 600 μm. The moisture content of the A1 product obtained was measured as 4.0%. SAP G PRE-PRODUCT
[00145] A superabsorbent polymer can be produced as follows. In a polyethylene vessel equipped with a stirrer and cooling coils, 1.93 kg of 50% NaOH and 2.71 kg of deionized water were added and cooled to 20 ° C. 0.83 kg of glacial acrylic acid was then added to the caustic solution and the solution was cooled again to 20 ° C. 4.96 g of polyethylene glycol monoaliether acrylate, 4.96 g of trimethylol propane ethoxylated triacrylate product SARTOMER® 454 and 1.65 kg of glacial acrylic acid were added to the first solution, then they were cooled to 4 to 6 ° C . Nitrogen was foamed through the monomer solution for about 5 minutes. A separate solution was prepared by dissolving 18.23 g of sodium bicarbonate, 0.151 g of Tween80 and 0.151 g of Span20 in 0.58 kg of water. The mixture was added to the monomeric solution and mixed with a Silverson High Shear Mixer at 7,500 RPM for 40 seconds. The monomeric solution was then discharged into a rectangular tray. 80 g of 1% by weight of H202 in aqueous solution, 120 g of 2% by weight of aqueous sodium persulfate solution and 72 g of 0.5% by weight of aqueous sodium erythorbate solution was added to the solution monomeric to initiate the polymerization reaction. The stirrer was stopped and the initiated monomer was allowed to polymerize for 20 minutes.
[00146] The resulting hydrogel was sliced and extruded with a commercial Hobart 4M6 extruder, then dried in a Procter & Schwartz Model 062 forced air oven at l75 ° C for 13 minutes with upward flow and 7 minutes with downward flow air in a 50 cm x 100 cm (20 inch x 40 inch) perforated metal tray at a final product moisture level of less than 5% by weight. The dry material was coarsely ground in a Prodeva Model 315-S crusher, ground in a MPI 666-F three-stage roller mill and sieved with Minox MTS 600DS3V to remove particles larger than 700 μm and smaller than 150 μm. The obtained G-product contained between 10 and 14% of particles larger than 600 μm. SAP H PRE-PRODUCT
[00147] A superabsorbent polymer can be produced as follows. In a polyethylene vessel equipped with a stirrer and cooling coils, 2.01 kg of 50% NaOH and 3.21 kg of distilled water were added and cooled to 20 ° C. 0.83 kg of glacial acrylic acid was then added to the caustic solution and the solution was cooled again to 20 ° C. 14.88 g of polyethylene glycol 300 diacrylate, 4.96 g of Dinasilane 6490 and 1.65 kg of glacial acrylic acid were added to the first solution, then it was cooled to 4 to 6 ° C. Nitrogen was foamed through the monomer solution for about 5 minutes. The monomeric solution was then discharged into a rectangular tray. 80 g of 1% by weight of H202 in aqueous solution, 120 g of 2% by weight of aqueous sodium persulfate solution and 72 g of 0.5% by weight of aqueous sodium erythorbate solution was added to the monomeric solution for initiate the polymerization reaction. The stirrer was stopped and the initiated monomer was allowed to polymerize for 20 minutes.
[00148] A particulate superabsorbent polymer can be prepared as follows. The resulting hydrogel was sliced and extruded with a commercial Hobart 4M6 extruder, then dried in a forced air oven Procter & Schwartz Model 062 at 175 ° C for 12 minutes with upward flow and 6 minutes with downward air flow in a tray perforated metal of 50 cm x 100 cm (20 inches x 40 inches) at a final product moisture level of less than 5% by weight The dried material was coarsely ground in a Prodeva Model 315-S mill, ground in a MPI 666-F three-stage roller mill and sieved with a Minox MTS 600DS3V to remove particles larger than 700 μm and smaller than 150 μm. The obtained product H contained 10 and 14% of particles larger than 600 μm. SAP I PRE-PRODUCT
[00149] A superabsorbent polymer can be produced as follows. In a polyethylene vessel equipped with a stirrer and cooling coils, 1.93 kg of 50% NaOH and 3.31 kg of distilled water were added and cooled to 20 ° C. 0.83 kg of glacial acrylic acid was then added to the caustic solution and the solution was cooled again to 20 ° C. 3.97 g of polyethylene glycol 300 diacrylate, 6.45 g of Dinasilane 6490 and 1.65 kg of glacial acrylic acid were added to the first solution, then it was cooled to 4 to 6 ° C. Nitrogen was foamed through the monomer solution for about 5 minutes. The monomeric solution was then discharged into a rectangular tray. 80 g of 1% by weight of H202 in aqueous solution, 120 g of 2% by weight of aqueous sodium persulfate solution and 72 g of 0.5% by weight of aqueous sodium erythorbate solution was added to the monomeric solution for initiate the polymerization reaction. The stirrer was stopped and the initiated monomer was allowed to polymerize for 20 minutes.
[00150] A particulate superabsorbent polymer can be prepared as follows. The resulting hydrogel was sliced and extruded with a commercial Hobart 4M6 extruder, then dried in a forced air oven Procter & Schwartz Model 062 at 175 ° C for 12 minutes with upward flow and 6 minutes with downward air flow in a tray perforated metal of 50 cm x 100 cm (20 inches x 40 inches) at a final product moisture level of less than 5% by weight The dried material was coarsely ground in a Prodeva Model 315-S mill, ground in a MPI 666-F three-stage roller mill and sieved with Minox MTS 600DS3V to remove particles larger than 700 μm and smaller than 150 μm. The obtained product I contained 10 and 14% of particles larger than 600 μm. SAP J PRE-PRODUCT
[00151] A superabsorbent polymer can be produced as follows. In a polyethylene vessel equipped with a stirrer and cooling coils, 1.93 kg of 50% NaOH and 2.70 kg of distilled water were added and cooled to 20 ° C. 0.83 kg of glacial acrylic acid was then added to the caustic solution and the solution was cooled again to 20 ° C. 7.69 g of polyethylene glycol 300 diacrylate, 8.18 g of Dinasilane 6490 and 1.65 kg of glacial acrylic acid were added to the first solution, then it was cooled to 4 to 6 ° C. Nitrogen was foamed through the monomer solution for about 5 minutes. A separate solution was prepared by dissolving 18.27 g of sodium bicarbonate, 0.151 g of Tween 80 and 0.151 g of Span20, in 0.58 kg of water. The mixture was added to the monomeric solution and mixed with a Silverson High Shear Mixer at 7,500 RPM for 40 seconds. The monomeric solution was then discharged into a rectangular tray. 80 g of 1% by weight of H2O2 in aqueous solution, 120 g of 2% by weight of aqueous sodium persulfate solution and 72 g of 0.5% by weight of aqueous sodium erythorbate solution was added to the monomeric solution for initiate the polymerization reaction. The stirrer was stopped and the initiated monomer was allowed to polymerize for 20 minutes.
[00152] A particulate superabsorbent polymer can be prepared as follows. The resulting hydrogel was sliced and extruded with a commercial Hobart 4M6 extruder, then dried in a forced air oven Procter & Schwartz Model 062 at 175 ° C for 12 minutes with upward flow and 6 minutes with downward air flow in a tray perforated metal of 50 cm x 100 cm (20 inches x 40 inches) at a final product moisture level of less than 5% by weight The dried material was coarsely ground in a Prodeva Model 315-S mill, ground in a MPI 666-F three-stage roller mill and sieved with a Minox MTS 600DS3V to remove particles larger than 700 μm and smaller than 150 μm. The pre-product J obtained contained 10 and 14% of particles larger than 600 μm. NEUTRALIZED ALUMINUM SALT C
[00153] 200 g of aluminum sulfate solution (20% aqueous solution) were stirred in a beaker with a magnetic stir bar. To this solution was added the sodium hydroxide solution (50% aqueous solution) until the pH of the mixture reached 7. 130 g total sodium hydroxide solution were consumed. The white colloidal suspension was stirred for 15 minutes and additionally clamped with a Tumax mixer for about 1 minute to break up pasta. The neutralized aluminum solution was used to modify the SAP without further purification. NEUTRALIZED ALUMINUM SALT D
[00154] 120 g of aluminum sulfate solution (20% in aqueous solution) were stirred in a beaker with a magnetic stir bar. To this solution was added the sodium aluminate solution (20% in aqueous solution) until the pH of the mixture reached 6.5. Total 60 g of sodium aluminate solution was consumed. The white colloidal suspension was stirred for 15 minutes and additionally clamped with the Tumax mixer for about 1 minute to break up pasta. The neutralized aluminum solution was used to modify the SAP without further purification. NEUTRALIZED ALUMINUM SALT AND
[00155] To a 100 mL beaker were added 49 g of lactic acid (88%, commercially available from ADM) and 161.5 g of water. The beaker was cooled in an ice bath and the solution was stirred with a magnetic stir bar. A solution of sodium aluminate (73.2 g, 43% w / w in water) was added to the beaker. Then, a solution of aluminum sulfate hydrate (59.3 g, 48% w / w in water) was added to the beaker. The resulting mixture was a clear solution with a pH value of 6.3. The neutralized aluminum salt solution obtained was used to modify the SAP surface. NEUTRALIZED ALUMINUM SALT F
[00156] To a 100 mL beaker, 19.2 g of glycolic acid (commercially available from Sigma-Aldrich) and 130.1 g of water were added. The beaker was cooled in an ice bath and the solution was stirred with a magnetic stir bar. A solution of sodium alumina (103.7 g, 20% w / w in water) was added to the beaker. Then, a solution of aluminum sulfate hydrate (44.9 g, 40% w / w in water) was added to the beaker. The resulting mixture was a clear solution with a pH value of 6.0. The neutralized aluminum salt solution obtained was used to modify the SAP surface. COMPARATIVE EXAMPLE 1
[00157] 4 g of aluminum sulfate hydrate solution (48% w / w in water) and 12 g of ethylene carbonate solution (33% w / w in water) were applied to the 400 g surface of the pre- SAP A product by using a finely atomized spray from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.1%. The average APP ((4.83 kPa) 0.7 psi) of the product is 21.7. COMPARATIVE EXAMPLE 2
[00158] 6 g of sodium aluminate solution (33% w / w in water) and 12 g of ethylene carbonate solution (33% w / w in water) were applied to the surface of 400 g of pre-product of SAP A by the use of a finely atomized spray from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.2%. The average APP (0.7 psi) of the product is 20.7. COMPARATIVE EXAMPLE 3
[00159] 16 g of the neutralized aluminum salt solution C and 8 g of the ethylene carbonate solution (50% w / w in water) were applied to the surface of 400 g of SAP A pre-product by using a sprinkler finely atomized from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.13%. The average APP ((4.83 kPa) 0.7psi) of the product is 20.1. COMPARATIVE EXAMPLE 4
[00160] 11.4 g of the neutralized aluminum salt solution E was mixed with 12 g of ethylene carbonate solution (33% w / w in water). The mixture was applied to the surface of 400 g of SAP A pre-product by using a finely atomized spray from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.2%. The average AAP (0.7psi) of the product is 19.7. COMPARATIVE EXAMPLE 5
[00161] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP A pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled to below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 8.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a cross-linked surface using a finely atomized spray of a Paasche VL aspersor while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 2.3%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 21.7. EXAMPLE 1
[00162] 16 g of the neutralized aluminum salt solution C and 8 g of the ethylene carbonate solution (50% w / w in water) were applied to the surface of 400 g of the SAP A pre-product by using a sprinkler finely atomized from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.13%. The particulate material with a cross-linked surface was cooled to below 60 ° C and coated with a solution containing 0.4 g of polyethylene glycol (molecular weight 8,000) and 40 g of deionized water. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 7.9%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 18.8. EXAMPLE 2
[00163] 16 g of the neutralized aluminum salt solution C and 8 g of the ethylene carbonate solution (50% w / w in water) were applied to the surface of 400 g of SAP A pre-product by using a sprinkler finely atomized from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.13%. The particulate material with a cross-linked surface was cooled below 60 ° C and coated with a solution containing 0.4 g of polyethylene glycol (molecular weight 8,000), 1.6 g of sodium lactate and 40 g of deionized water. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 7.9%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 18.9. EXAMPLE 3
[00164] 16 g of neutralized aluminum salt solution C and 8 g of ethylene carbonate solution (50% w / w in water) were applied to the surface of 400 g of SAP A pre-product by using a sprinkler finely atomized from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.13%. The particulate material with a cross-linked surface was cooled to below 60 ° C and coated with a solution containing 0.4 g of polyethylene glycol (molecular weight 8,000), 1.6 g of sodium gluconate and 40 g of deionized water. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 7.8%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 18.9. EXAMPLE 4
[00165] 16 g of the neutralized aluminum salt solution D and 8 g of the ethylene carbonate solution (50% w / w in water) were applied to the surface of 400 g of the SAP A pre-product by using a sprinkler finely atomized from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.13%. The particulate material with a cross-linked surface was cooled to below 60 ° C and coated with a solution containing 0.4 g of polyethylene glycol (molecular weight 8,000) and 40 g of deionized water. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 7.5%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 18.7. EXAMPLE 5
[00166] 16 g of the neutralized aluminum salt solution D and 8 g of the ethylene carbonate solution (50% w / w in water) were applied to the surface of 400 g of the SAP A pre-product by using a sprinkler finely atomized from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.13%. The particulate material with a cross-linked surface was cooled below 60 ° C and coated with a solution containing 0.4 g of polyethylene glycol (molecular weight 8,000), 1.6 g of sodium lactate and 40 g of deionized water. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 7.6%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 18.6. EXAMPLE 6
[00167] 16 g of the neutralized aluminum salt solution D and 8 g of the ethylene carbonate solution (50% w / w in water) were applied to the surface of 400 g of the SAP A pre-product by using a sprinkler finely atomized from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 0.13%. The particulate material with a cross-linked surface was cooled to below 60 ° C and coated with a solution containing 0.4 g of polyethylene glycol (molecular weight 8,000), 1.6 g of sodium gluconate and 40 g of deionized water. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product obtained was measured as 7.8%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 18.2. EXAMPLE 7
[00168] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP A pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 28.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a cross-linked surface using a finely atomized spray of a Paasche VL aspersor while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The product obtained contained 33% of particles larger than 600 μm. The moisture content of the product was measured as 7.1%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 19.7. EXAMPLE 8
[00169] As in Example 9 except for the screens that have been changed to 25/100 US standard screens. The product obtained contained 12% of particles larger than 600 μm. The moisture content of the product was measured as 7.5%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 19.0. EXAMPLE 9
[00170] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP B pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 30 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 28.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a crosslinked surface using a finely atomized spray from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The product obtained contained 25% of particles larger than 600 μm. The moisture content of the product was measured as 7.7%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 20.3. EXAMPLE 10
[00171] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP A pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 40.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a crosslinked surface using a finely atomized spray from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product was measured as 11%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 19.6. EXAMPLE 11
[00172] 4 g of ethylene carbonate were dissolved in 19.7 g of the neutralized aluminum salt solution F and the mixture was applied to the 400 g surface of the SAP A pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 12 g of the neutralized aluminum salt solution F, 0.4 g of polyethylene glycol (molecular weight 8,000) and 32.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a crosslinked surface using a finely atomized spray from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The moisture content of the product was measured as 8.5%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 19.0. EXAMPLE 12
[00173] 16 g of the ethylene carbonate solution (25% w / w in water) was applied to the 400 g surface of the SAP A pre-product by using a finely atomized spray from a Paasche VL sprinkler while the particles of SAP were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 24.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a crosslinked surface using a finely atomized spray from a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The product obtained contained 25% of particles larger than 600 μm. The moisture content of the product was measured at 7.7%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 18.5. EXAMPLE 13
[00174] As in Example 12 except that the neutralized aluminum salt solution F was used in place of E. The moisture content of the product obtained was measured as 6%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 19.3. EXAMPLE 14
[00175] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP A1 pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 45 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 28.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a cross-linked surface using a finely atomized spray of a Paasche VL aspersor while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The product obtained contained 7.9% of particles larger than 600 μm and had a PSD medium of 398 μm. The moisture content of the product was measured as 7.0%. Product properties included a CRC of 30.2 g / g, AUL ((6.2 kPa) 0.9 psi) of 17.8 g / g, AAP ((4.83 kPa) 0.7 psi) of 18 , 9 g / g and a GBP of 46.2 x 10-8cm2. EXAMPLE 15
[00176] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP G pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 32.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a cross-linked surface using a finely atomized spray of a Paasche VL aspersor while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The product obtained contained 5.5% of particles larger than 600 μm and had 397 μm PSD media. The moisture content of the product was measured as 7.3%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 18.2 g / g and the Vortex time of Example 15 is 27 seconds. EXAMPLE 16
[00177] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP H pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 32.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a cross-linked surface using a finely atomized spray of a Paasche VL aspersor while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The product obtained contained 7.4% of particles larger than 600 μm and had a PSD medium of 398 μm. The moisture content of the product was measured as 7.8%. The average AAP ((4.83 kPa) 0.7 psi) of the product is 21.3 g / g and the Vortex time of Example 16 is 85 seconds and the CRCI is 4.1 g / g. EXAMPLE 17
[00178] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP 1 pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 55 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 32.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a cross-linked surface using a finely atomized spray of a Paasche VL aspersor while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The product obtained contained 9.0% of particles larger than 600 μm and had a PSD medium of 425 μm. The moisture content of the product was measured as 7.8%. The average AAP (0.7 psi) of the product is 19.1 g / g and the Vortex time of Example 17 is 77 seconds and the CRCI is 8.6 g / g. EXAMPLE 18
[00179] 11.4 g of the neutralized aluminum salt solution E were mixed with 12 g of the ethylene carbonate solution (33% w / w in water). The mixture was applied to the 400 g surface of the SAP J pre-product by using a finely atomized spray of a Paasche VL sprinkler while the SAP particles were fluidized in air and continuously mixed. The coated material was then heated in a convection oven at 185 ° C for 45 minutes for surface crosslinking. The particulate material with a cross-linked surface was cooled below 60 ° C. 11.4 g of the neutralized aluminum salt solution E, 0.4 g of polyethylene glycol (molecular weight 8,000) and 32.0 g of deionized water were mixed to generate a clear solution. The resulting mixture was applied to the particulate material with a cross-linked surface using a finely atomized spray of a Paasche VL aspersor while the SAP particles were fluidized in air and continuously mixed. The coated material was relaxed at room temperature for one day and then sieved with US standard 20/100 mesh sieves to remove particles larger than 850 μm and smaller than 150 μm. The product obtained contained 15.1% of particles larger than 600 μm and had a PSD medium of 441 μm. The moisture content of the product was measured as 8.9%. The average AAP (4.83 kPa) 0.7 psi) of the product is 19.5 g / g and the vortex time of Example 18 is 35 seconds and the CRCI is 7.5 g / g. TABLE 2

TABLE 3

[00180] Notwithstanding the fact that the numerical ranges and parameters that present the broad scope of the invention are approximations, the numerical values presented in the specific examples are reported as precisely as possible. Unlike operational examples, or where otherwise indicated, all numbers that express quantity of ingredients, reaction conditions and so on used in the specification and in the claims should be understood as being modified in all instances by the term "fence" in". Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in the respective test measurements.

权利要求:
Claims (10)
[0001]
1. Particulate superabsorbent polymeric composition, characterized by the fact that it comprises a superabsorbent particulate polymer comprising from 0.05 to 2.0% by weight, based on the total amount of the polymerizable unsaturated acid group, which contains monomeric solution of a foaming agent and from 0.001 to 1.0% by weight, based on the total amount of the polymerizable unsaturated acid group, which contains monomeric solution of a mixture of a lipophilic surfactant and a polyethoxylated hydrophilic surfactant, and 0, 01% by weight to 5% by weight, based on the weight of the particulate superabsorbent polymeric composition, of a neutralized aluminum salt applied to the surface of the particulate superabsorbent polymer, in the form of an aqueous neutralized aluminum salt solution, which has a value pH from 5.5 to 8; and the particulate superabsorbent polymer composition has a Centrifugal Retention Capacity (CRC) of 25 grams to 40 grams of 0.9 percent by weight of aqueous sodium chloride per gram of the particulate superabsorbent polymer composition, with CRC being measured before or after submitting the superabsorbent polymeric composition to a Processing Test and an absorbance under load at 6.2 kPa (0.9 psi) before submitting the particulate superabsorbent polymeric composition to the 15 g / ga Processing Test 21 g / g and a Free Dilatation Gel Bed Permeability (FSGBP) of 30 x 10-8 cm2 to 200 x 10-8 cm2 before submitting the particulate superabsorbent polymeric composition to the Processing Test; the particulate superabsorbent polymer composition has a Vortex time of 25 to 60 seconds as measured by the Vortex Test and has a permeability stability index of 0.60 to 0.99 when submitting the particulate superabsorbent polymer composition to a Processing Test and a compressibility of 1.30 mm2 / N to 4 mm2 / N as measured by the Compression Test; being that the said particulate superabsorbent polymeric composition is, after a heat treatment step, treated with an aqueous solution of water-soluble polymer, and the composition of the treated superabsorbent polymer has a moisture content of 5% to 11% by weight, based on the particulate superabsorbent polymeric composition.
[0002]
2. Particulate superabsorbent polymeric composition, according to claim 1, characterized by the fact that the lipophilic nonionic surfactant has an HLB of 4 to 9 and the hydrophilic polyethoxylated nonionic surfactant has an HLB of 12 to 18.
[0003]
3. Particulate superabsorbent polymeric composition, according to claim 1, characterized by the fact that the mixture of a lipophilic non-ionic surfactant and a polyethoxylated hydrophilic non-ionic surfactant presents an HLB of 8 to 14.
[0004]
4. Particulate superabsorbent polymer according to claim 3, characterized by the fact that the lipophilic non-ionic surfactant is a sorbitan ester and the polyethoxylated hydrophilic non-ionic surfactant is a polyethoxylated sorbitan ester.
[0005]
5. Particulate superabsorbent polymeric composition according to claim 1, characterized in that it comprises an internal crosslinking agent comprising a silane compound comprising at least one vinyl group or allyl group and at least one Si-O bond , with the vinyl group or allyl group being directly linked to a silicon atom, and the particulate superabsorbent polymer composition has an increase in Centrifugal Retention Capability (CRC) of at least 2 g / g based on CRC = CRC (tc, 5 h) - CRC (ta, 0.5 h) and the CRC Increase measures the increase in CRC that occurs and is calculated as the difference between the second CRC Test and the first CRC Test and tc refers to body temperature and ta refers to room temperature.
[0006]
6. Particulate superabsorbent polymeric composition, according to claim 5, characterized by the fact that said silane compound is selected from one of the following
[0007]
7. Particulate superabsorbent polymeric composition according to claim 6, characterized by the fact that said silane compound is selected from vinyltrisopropenoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, diethoxymethylvinylsilane and polysiloxane comprising at least two groups vinyl.
[0008]
8. Particulate superabsorbent polymeric composition, characterized by the fact that it comprises a particulate superabsorbent polymer comprising an internal crosslinking agent comprising a silane compound comprising at least one vinyl group or allyl group and at least one Si bond. O, with the vinyl group or allyl group being directly attached to a silicon atom and from 0.01% by weight to 5% by weight based on the weight of the particulate superabsorbent polymer composition of a neutralized aluminum salt applied to the surface of the particulate superabsorbent polymer, in the form of an aqueous neutralized aluminum salt solution which has a pH value of 5.5 to 8; the particulate superabsorbent polymer composition has a Centrifugal Retention Capacity (CRC) of 25 grams to 40 grams of 0.9 percent by weight of aqueous sodium chloride per gram of the particulate superabsorbent polymer composition, being that the CRC is measured before or after submitting the superabsorbent polymeric composition to a Processing Test and an absorbance under load at 6.2 kPa (0.9 psi) before submitting the superabsorbent polymeric composition particulate to the Processing Process Test. 15 g / g to 21 g / g and an original Free Expansion Gel Bed Permeability (FSGBP) of 30 x 10-8 cm2 to 200 x 10-8 cm2 before submitting the particulate superabsorbent polymeric composition to the Processing Test; and a permeability stability index of 0.60 to 0.99 when submitting the particulate superabsorbent polymeric composition to a Processing Test and a compressibility of 1.30 mm2 / N to 4 mm2 / N as measured by the Test of Compression and an Increase in Centrifugal Retention Capacity (CRC) of at least 2 g / g or more based on Increase in CRC = CRC (tc, 5 h) - CRC (ta, 0.5 h) with CRC measures the increase in CRC that occurs and is calculated as the difference between the second CRC Test and the first CRC Test and tc refers to body temperature and ta refers to room temperature; the said particulate superabsorbent polymer composition is, after a heat treatment step, treated with an aqueous solution of water-soluble polymer, and the composition of the treated superabsorbent polymer has a moisture content of 5% to 11% by weight, based on the particulate superabsorbent polymeric composition.
[0009]
9. Particulate superabsorbent polymeric composition, according to claim 8, characterized by the fact that said silane compound is selected from one of the following
[0010]
10. Particulate superabsorbent polymeric composition according to claim 9, characterized by the fact that said silane compound is selected from vinyltrisopropenoxysilane, vinyltriacetoxy silane, vinyltrimethoxysilane, vinyltriethoxysilane, diethoxymethylvinylsilane and polysiloxane and comprises at least two groups vinyl.

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同族专利:

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公开号 | 公开日

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US20140306156A1|2014-10-16|

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JP2019031691A|2019-02-28|

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TW201503918A|2015-02-01|

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KR20150143624A|2015-12-23|

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WO2014167040A1|2014-10-16|

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BR112015025521A2|2017-07-18|

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JP2016514761A|2016-05-23|

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TWI637995B|2018-10-11|

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BR112015025560A2|2020-10-20|

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KR102018489B1|2019-09-11|

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KR20150140800A|2015-12-16|

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CN105283490A|2016-01-27|

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EP2984125A1|2016-02-17|

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KR102018488B1|2019-09-11|

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EP2984124B1|2019-02-27|

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JP6720271B2|2020-07-08|

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JP6510488B2|2019-05-08|

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WO2014168858A1|2014-10-16|

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TW201504314A|2015-02-01|

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US9375507B2|2016-06-28|

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EP2984124A1|2016-02-17|

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法律状态:
2018-02-27| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|

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2019-12-10| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|

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2020-10-20| B09A| Decision: intention to grant|

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2020-12-15| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 07/04/2014, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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US13/860,019|US9302248B2|2013-04-10|2013-04-10|Particulate superabsorbent polymer composition having improved stability|

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US13/860,019|2013-04-10|

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US14/157,769|US9375507B2|2013-04-10|2014-01-17|Particulate superabsorbent polymer composition having improved stability|

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US14/157,769|2014-01-17|

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PCT/US2014/033142|WO2014168858A1|2013-04-10|2014-04-07|Particulate superabsorbent polymer composition having improved stability and fast absorption|

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