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    • 专利摘要:
    Composite material of nanocellulose and fibrous clays, manufacturing and use procedure. The invention relates to a stable composite material comprising defibrated cellulose and particles of fibrous morphology or silicate fibers belonging to the family of fibrous clays, nanometrically entangled. Furthermore, the invention relates to a process for preparing said composite material and its uses as adsorbents, absorbent thickening agents, food additives, catalyst supports, enzyme supports, drug carriers, flame retardants and self-extinguishing materials, additives of cements, special papers, elements of sensor materials, among others. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2558472A1
    申请号:ES201431000
    申请日:2014-07-03
    公开日:2016-02-04
    发明作者:Eduardo Ruiz Hitzky；María Pilar Aranda Gallego；Margarita María DARDER COLOM；María Del Mar GONZÁLEZ DEL CAMPO RODRÍGUEZ BARBERO
    申请人:Consejo Superior de Investigaciones Cientificas CSIC；
    IPC主号:
    专利说明:

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    COMPOSITE MATERIAL OF NANOCELLULOSE AND FIBER CLAYS, MANUFACTURING AND USE PROCEDURE DESCRIPTION
    5 SECTOR OF THE TECHNIQUE AND OBJECT OF THE INVENTION
    The invention relates to a stable composite material comprising defibrated cellulose and fibrous morphology particles or silicate fibers belonging to the family of
    10 fibrous clays, intertwined nanometrically.
    Other objects of the invention are a process for preparing the composite material which comprises homogenizing the two fibrous components, clay and defibrated cellulose, in an aqueous medium until a stable hydrogel is obtained; and the use of this type of materials
    15 composites such as adsorbents, absorbent thickeners, feed additives, catalyst supports, enzyme supports, drug carriers, flame retardants and self-extinguishing materials, cement additives, special papers, sensing material elements, etc.
    The technical field of the invention falls within the technical sector of new materials, in particular nanostructured composite materials. STATE OF THE TECHNIQUE
    25 The nanocomposite materials or "nanocomposites" are a type of nanostructured organic-inorganic hybrid material, generally composed of a polymeric matrix and an inorganic phase dispersed in said matrix that interact at the nanometric level generating synergistic and / or improved properties that affect a multitude of Applications. Within these composite materials or "composites", bionanocomposites are
    30 nanocomposites in which the polymer matrix is a biopolymer, that is, a polymer of natural origin. In a large number of bionanocomposites, the inorganic component is a silicate that belongs to the family of clay minerals, whether they are laminar type such as smectites and vermiculites, either fibrous type such as sepiolite or palygorskite. These silicates combine unique properties such as chemical inertia, the
    35 low or no toxicity and good biocompatibility, together with high absorption capacity, ion exchange properties and high surface area. These characteristics are essential to ensure a strong interaction with biopolymers through different mechanisms, such as hydrogen bonds, electrostatic interactions and Van der Waals forces.
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    5 Composite materials prepared from components of natural origin (biocomposites) currently represent a topic of great interest with a view to the development of advanced functional and / or structural materials, not only because they are ecological materials with all their components of natural origin, but also for his
    10 great versatility in various applications. Thus, recent studies have shown that the fibrous minerals of clay, such as sepiolite and palygorskite, also called attapulgite, are of great interest as reinforcing agents in both petroleum-derived polymers and biopolymeric matrices. In particular, the biocomposites resulting from the incorporation of fibrous clays to different types of polysaccharides such as
    15 starch, chitosan and alginate, has allowed the obtaining of composite materials that have good mechanical properties along with interesting properties such as the reduction of water absorption compared to pure biopolymers.
    On the other hand, polysaccharides of the cellulose type of diverse origin are potentially
    20 of great interest for its combination with clays and thus be able to obtain composite materials. The high aspect ratio of cellulose fibers and their hydroxyl group content makes this biopolymer a desired component due to its mechanical properties and functional capacity. An important limitation is its insoluble nature, which until now has been overcome by preparing different cellulose derivatives by
    25 diverse chemical reactions. This is the case of cellulose derivatives such as cellulose acetates, cellulose ethers and cellulose esters and specifically, for example, hydroxymethyl cellulose, hydroxyethyl cellulose, propylmethylhydroxycellulose or carboxymethyl cellulose, some of them used in combination with various clays , including fibrous clays. So far various resulting composites have been described
    30 of the combination of said cellulose derivatives with sepiolite and palygorskite (E. Ruiz-Hitzky et al., Progress in Polymer Science, 38,2013, 1392-1414).
    A relatively recent discovery concerns the micro- and nano-materials based on various aggregation states of the individual chains of the cellulose polysaccharide in 35 crystalline and amorphous regions, causing elementary fibrils that in turn make up the cellulose fibers. By means of disaggregation processes of these larger fibers, elementary fibrils can be obtained, also called "defibrated cellulose". Of special interest are the fibrous materials produced from cellulose with dimensions in the micrometer range or from cellulose particles having at least one dimension in the nanometric scale. In the first case, cellulose with micrometric dimensions is known as "microcrystalline cellulose" or microcellulose, which is formed by partially depolymerized cellulose fibers with the help of chemical and mechanical treatments, presenting fiber lengths between 50 and 10 μm and diameter of the order of 10-50 μm. In the second case, the cellulose particles having at least one dimension on the nanometric or nanocellulosic scale are called "microfibrillated cellulose", "nanofibrillated cellulose" and "nanocrystalline cellulose". The "microfibrillated cellulose" has lengths between 0.5 and 10 μm and diameters in the range of 10 to 100 nm, while "nanofibrillated cellulose" and "nanocrystalline cellulose" have fiber lengths in the ranges 500 to 2000 nm and 50 to 500 nm, respectively, as well as diameters of 4 to 20 nm and 3 to 5 nm, respectively (RJ Moon et al., Chemical Society 15 Reviews, 40, 2011, 3941-3994; Y. Habibi, Chemical Society Reviews , 43, 2014, 1519-1542;
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    S. Kalia et al., Colloid Polymer Science, 292, 2014, 5–31). Microcelluloses and nanocelluloses have very different physical-chemical characteristics from those of native cellulose and open the way to new applications. Especially cellulose defibrated to the nanometric scale or nanocelluloses, such as "microfibrillated cellulose", "cellulose
    20 nanofibrillated "and" nanocrystalline cellulose ", have a marked aspect ratio length-diameter and formation capacity of stable aqueous viscosity gels. On the other hand, it should be noted that in plants, cellulosic materials are associated with hemicellulose so as with lignin, so lignocellulosic compounds are also among the related materials.
    25 To date, microcelluloses and nanocelluloses formed from defibrated cellulose have been used in the preparation of composites with clays of laminar structure, mainly montmorillonite and vermiculite (A. Liu et al., Carbohydrate Polymers, 87, 2012, 53 - 60; T. Nypelö et al., Cellulose, 19, 2012, 779-792; TTT Ho et al., Journal of
    30 Materials Science 47, 2012, 4370-4382).
    WO2013126321A1 indicates a material that comprises nanocellulose and fibrous clays but that requires at least 5 components to form.
    35 US20120094953A1 presents a process for the production of defibrated nanocellulose suspensions combining cellulose fibers and a filler (additives and / or filler) and / or 4
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    Pigment that may include sepiolite. This document does not indicate that the combination of these nanofibers with any fibrous clay occurs at a nanometric level, nor are the properties or characteristics improved or differentiated with respect to the starting materials.
    5 On the other hand, in the case of sepiolite, the fibers that make up this mineral are forming skeins that make it difficult to disintegrate and disperse in water to form stable gels, however wet milling and homogenization processes (ES8505893, ES8506358, ES8505894 and EP0170299), allow to obtain materials known as
    10 rheological grade sepiolites, capable of producing high viscosity suspensions at relatively low concentrations of dispersed solids, when compared with lamellar clays of the montmorillonite type with very low surface density in hydroxyl groups of the silanoles type (Si- OH). In addition, although some research speaks of anchoring reactions through this type of lamellar clays hydroxyl groups, the
    The content in these groups is very scarce and they are only present at the edges of the material, so modifications cannot be made based on the reactivity of said groups that affect the entire surface of the clay. Palygorskite is a structural clay and morphologically related to sepiolite, however palygorskite preparation methods have not been described that develop rheological grade materials similar to those of
    20 sepiolite
    Ultrasonic sepiolite treatments generate colloidal sepiolite suspensions in which due to fiber breakdown, the mineral has a greater ability to associate on a nanometric scale with different types of compounds (I. Küncek et al.,
    25 Ultrasonics Sonochemistry, 17, 2010, 250-257; C. Maqueda et al., Applied Clay Science, 46, 2009, 289-295). However, these treatments are focused on achieving a better dispersion of the clay and not on achieving the formation of composite materials with a material based on microcellulose or nanocellulose, which are also not soluble.
    30 A combination to the nanometric scale of fibrous clays such as sepiolite and palygorskite with defibrated cellulose, starting from both "microcrystalline cellulose" or microcellulose and nanocellulose, including "microfibrillated cellulose", "nanofibrillated cellulose" and "nanocrystalline cellulose", would allow obtain a material composed of two types of nanofibers or fibrils, cellulose and fibrous silicate, capable of generating in water
    Homogeneous, stable and viscous hydrogels due to the interaction between the surface hydroxyl groups of both fibrous components. This combination is not immediate 5
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    because, among other things, defibrated cellulose is not soluble, and so far the treatments found require chemical treatments in the presence of other compounds. This material would have many applications due to the nature of the materials and their structuring.
    5 It has been proven that stable dispersions of nanotubes or carbon nanofibers have been formed in the presence of sepiolite using ultrasound (ES2361763B1). Once the water has been removed from these dispersions, solids of a sepiolitan carbon tube hybrid nature are produced, resulting in materials called "hybrid buckypapers"
    10 composed of the cross-linking of sepiolite fibers and multipared carbon nanotubes, which possess synergistic properties of interest in various applications (F.M. Fernandes et al., Carbon, 72, 2014, 296-303). In relation to these works, the ability of cellulose defibrated at the nanometric level to combine with carbon nanotubes has also been described very recently (M.M. Hamedi, et al, ACS Nano, 8, 2014, 2467
    15 2476). However, until now no fibrous clay composite materials have been manufactured together with defibrated cellulose and carbon nanotubes that take advantage of the nature of these three compounds in a stable gel presentation that can be transformed into a solid phase. 20 EXPLANATION OF THE INVENTION
    A first aspect of the invention is a composite material comprising defibrated cellulose and fibrous clay whose fibrils are nanometrically bonded, the defibrated cellulose that forms the composite material can be microcellulose or nanocellulose and the
    25 sepiolite or palygorskite fibrous clay.
    The relative amounts by weight may vary and will depend on the starting materials. Thus, the relative amounts by weight of fibrous clay: nanocellulose are between 91: 9 and 2:98, more particularly between 50:50 and 34:66, while in the case of fibrous clay: microcellulose are between 40:60 and 60:40, more particularly in the 50:50 ratio.
    Defibrated cellulose can be of plant or microbial origin, of algae or recycled lignocellulosic residues.
    The second aspect of the invention is the process of preparing the composite material comprising the following steps:
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    a) mix the two fibrous components, clay and defibrated cellulose in water in the same container, b) strongly homogenize the mixture in the aqueous medium until a stable hydrogel is obtained.
    5 The starting materials can be mixed simultaneously directly from commercial material or prepared before mixing.
    In which in step a) mechanical mixers can be used to suspend the starting materials.
    The homogenization of stage b) can be carried out by means of a high shear and pressure homogenizer, by treatment in a microfluidizer or by application of a sonomechanical treatment by means of ultrasound. The sonomechanical treatment must be high
    15 energy and metal tip caviters or equipment with sonotrodes can be used, either in static and / or continuous mode.
    Ultrasonic irradiation can be performed in a pulsed manner. Preferably the amount of irradiated ultrasound is in a range between 100 J and 5000 J per 25 grams
    20 dispersion, and even more preferably the ultrasound irradiation that is performed cyclically in pulses of 5 to 20 seconds of irradiation, followed by 5 to 20 seconds of rest.
    The hydrogel-shaped composite material can be dried by eliminating the
    Water, so that it can be shaped to present in a defined form, such as monolithic blocks of predetermined dimensions, films of varying thickness, or foams of different density.
    Drying can be done by air drying, forced extraction of pressurized water
    Reduced, filtration, centrifugation, lyophilization, supercritical drying, spraying or atomizing processes, fluidized or fluidized beds, air flow cyclone or hot inert gas.
    Additionally, organic and / or inorganic additives can be incorporated into the composite material, to form a ternary or higher order compound based on the composite material.
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    The inorganic additive that is incorporated may be one or more of the following elements: a laminar clay or nano- or micro-metric particles of carbon nanotubes, carbon nanofibers, a metal, an oxide, or a metal salt; and the organic additive that is incorporated may include one or more of the following: a dye, an agent
    5 surfactant, or a polymeric material.
    Magnetic nanoparticles based on iron oxides of the magnetite type can also be incorporated.
    The composite material and / or ternary or higher order materials based on it can be additionally functionalized by chemical reactions or by assembling to nanoparticles of different nature.
    The composite material can be chemically modified to deliberately alter its
    Structural and / or functional properties, particularly is modified by reactions with silanes, epoxides, isocyanates, dialdehydes or with any other cross-linking reagent or coupling agent, more particularly by modifying silanes by silanization reactions of the hydroxyl functions of the material.
    A third aspect of the invention is the use of the composite material as adsorbent, absorbent, thickening agent, feed additive, catalyst support, enzyme support, flame retardant and self-extinguishing material, cement additives, wine production, packaging of special foods and papers such as nano paper. 25 DESCRIPTION OF THE INVENTION
    The inventors have synthesized a new stable composite material comprising defibrated cellulose (microcellulose or nanocellulose) and fibrous-looking particles or silicate fibers belonging to the family of fibrous clays (such as sepiolite and
    30 palygorskita or attapulgita) resulting from the nanometric assembly of the two types of fiber. This material does not require the addition of other materials to guarantee its stability in environmental conditions and is prepared in an aqueous medium; In addition, the composite material has different characteristics with respect to the starting materials and is potentially useful in many applications.
    35


    Thus, a first object of the invention is a composite material comprising defibrated cellulose and fibrous clay whose fibrils are nanometrically bonded.
    The presence of fibrous clays is an advantage over the previously described use of
    5 clays of laminar morphology such as montmorillonite and other smectites present as aggregates, since the fibrous clays considered here contain surface hydroxyl groups of the silanole group type, which together with their fibrous morphology provide greater efficiency in their interaction with defibrated cellulose .
    The composite material can be found in a homogeneous aqueous suspension forming a stable or solid phase hydrogel after the corresponding elimination of water by means of a drying process.
    The fundamental advantages of composite material refer to synergistic properties
    15 among the components that comprise it. For example, these fibrous hybrid systems can benefit from the properties provided by the components such as the mechanical properties characteristic of the microcellulose or nanocellulose fibrils, the adsorbent properties of the two components, their different and complementary chemical reactivity, the flame retardant effect of the sepiolite and palygorskite fibrils of the
    20 ability to assemble nanoparticles of metals and different metal oxides for the two components, of the different rheological behaviors, etc.
    In a particular embodiment, the defibrated cellulose that forms the composite material comprises at least one of the following materials: microcellulose, nanocellulose.
    In a particular embodiment, the fibrous clay comprises at least one of the following materials: sepiolite, palygorskite, more particularly sepiolite.
    In a more particular embodiment, the relative amounts by weight of fibrous clay: nanocellulose are between 91: 9 and 2:98, more particularly between 50:50 and 34:66.
    In another more particular embodiment, the relative amount by weight of fibrous clay: microcellulose is between 40:60 and 60:40, more particularly 50:50.
    In another particular embodiment, the defibrated cellulose is of plant or microbial origin, of algae or recycled lignocellulosic residues. 9
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    In particular, defibrated cellulose of vegetable origin can be obtained from paper pulp prepared from softwoods such as those of conifers such as pine, spruce, spruce and larch, from hardwoods such as eucalyptus, poplar and birch, or of plant vegetable fibers such as sugarcane (bagasse), flax, cotton and hemp. Cellulose
    5 defibrated can also come from residues of high cellulose content such as paper, cardboard and discarded textiles.
    A second aspect of the present invention is a composite material preparation process, which comprises the following steps: a) mixing the two fibrous components, clay and cellulose defibrated in the same container in water, b) strongly homogenizing the mixture in the aqueous medium until a stable hydrogel is obtained,
    A simple addition of the starting materials, fibrous clays and defibrated cellulose would not lead to the formation of the composite material of the invention, obtaining non-homogeneous gels or even with phase separation in the case of using microcellulose. In order to obtain a homogeneous and stable hydrogel, capable of giving rise to the final composite material, it is necessary the nanometric level association of the two types of fibers, which occurs in
    This invention is promoting the formation of hydrogen bonds between the hydroxyl groups found on the surface of the fibrous clay (silanoles groups) and the hydroxyl groups that make up the glycosidic chains of the microcellulose or nanocellulose fibers.
    In a particular embodiment, the starting materials or precursors (defibrated cellulose and fibrous clay) can be mixed simultaneously directly from commercial materials or prepared before mixing. For example, one option is to previously disaggregate the fibrous clay into the mixture by applying ultrasound.
    In another particular embodiment in step a) mechanical mixers can be used to suspend the materials and ensure that they disperse more quickly and homogeneously.
    In step b) homogenization is carried out until the hydrogel does not decant, the time of this stage depending on the nature and the amount of starting material.
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    In a particular embodiment, the homogenization of stage b) can be carried out by means of a high shear and pressure homogenizer, by treatment in a microfluidizer or more particularly by application of a sonomechanical treatment by means of ultrasound which must be of high energy preferably using cavitators of metal tips or
    5 teams with sonotrodes. Ultrasound can be applied in static or continuous mode.
    In an even more particular embodiment, ultrasonic irradiation is preferably carried out in a pulsed manner. More preferably, the amount of irradiated ultrasound is in a range between 100 J and 5000 J per 25 grams of dispersion. And even more
    10 preferably the ultrasound irradiation that is performed cyclically in pulses of 5 to 20 seconds of irradiation, followed by 5 to 20 seconds of rest.
    It is necessary to apply high energy homogenization methods in step b) to produce the disaggregation in aqueous medium of both types of organic and inorganic fibers simultaneously. This homogenization process is critical because it has been found that at least 100 J per 25 g of fibrillated fibrous cellulose clay mixture in water is necessary for stable gels of the composite material to be produced, when ultrasound irradiation is used, although this value may be superior when working with suspensions of fibrous clay and / or defibrated cellulose that require
    20 an additional energy to disaggregate. After this homogenization results in a hydrogel in which the recombination of the fibers that allows the formation of the composite material is favored.
    The use of sepiolite is considered advantageous compared to other lamellar clays because
    25 allows very stable gels to be formed in water through homogenization processes and this facilitates the preparation of the composite material.
    The homogenization processes produce a breakdown of the fibrils of the two types of components causing their cross-linking and cross-linking that gives rise to the composite material. The formation of nanocomposites requires an intimate and homogeneous combination of the two fibrous components involved here. For this, it is necessary to apply powerful homogenization methods such as ultrasound irradiation, which allow to temporarily undo the aggregates of cellulose nanofibers and fibrous silicate facilitating juxtaposition between the surface hydroxyl groups of both
    35 fibrous components. Thus, aqueous cellulose gels treated with sepiolite or with aqueous suspensions of sepiolite by conventional mixing methods for
    image10
    Low-energy mechanical or sonomechanical methods, such as magnetic stirring, vortex treatment or ultrasonic bathing, do not always lead to homogeneous suspensions that allow the composites of the invention to be prepared. Only powerful homogenization methods such as the use of high-energy ultrasound results in the disaggregation of cellulose fiber and fibrous silicate packages, favoring their recombination and the formation of composite material. With high-energy ultrasound, a stable hydrogel is obtained from microcrystalline cellulose and sepiolite with high viscosity with values close to 5000 cP. If mechanical mixing, vortex treatments or ultrasonic bathing are used, an immediate syneresis occurs with component separation (see a particular example in Figure 1).
    On the other hand, it should be noted that palygorskite does not form stable gels through homogenization treatments as an isolated material, however, surprisingly it has been found that when mixed with cellulose and applying the procedure, in particular, the sonomechanical treatment, the combination of both types of fibers producing stable hydrogels of the composite material of the invention.
    In a particular embodiment the method comprises the additional step of
    c) dry the stable hydrogel prepared in step b) by eliminating
    of the water,
    The composite material, which after step b) can be found in the form of hydrogel, can be shaped so that the material after drying in step c) is present in a defined form, such as monolithic blocks of predetermined dimensions, films of variable thickness, or foams of different density.
    In a particular embodiment the drying treatment of step c) of the process is carried out by air drying, forced extraction of water under reduced pressure, filtration, centrifugation, lyophilization, supercritical drying processes, spraying or atomization, fluidized or fluidized beds, Cyclone air flow or hot inert gas. Following any of these procedures, in the drying process, recombination of submicron size cellulose fibers is disadvantaged due to the interposition of mineral fibers between organic fibers.


    In a particular embodiment, organic and / or inorganic additives, hereinafter the additive, are incorporated to form a ternary or higher order compound based on the composite material.
    In a more particular embodiment, the inorganic additive that is incorporated may be one or more of the following elements: a laminar clay or nano- or micro-metric particles of carbon nanotubes, carbon nanofibers, of a metal, of an oxide, or of a metal salt.
    In a more particular embodiment it is possible to incorporate magnetic nanoparticles based on iron oxides of the magnetite type that confer magnetic or superparamagnetic properties to composites. The adsorption capacity of water-soluble organic dyes by fibrous clay can also be used to incorporate this type of molecule into the system capable of strongly retaining this type of
    15 dyes, applicable to remove dyes (water contaminants).
    In another more particular embodiment, the organic additive may be a dye, a surfactant, or a polymeric material: the introduction of these additives would allow new material properties to be obtained.
    In another particular embodiment, the composite material or ternary or higher order materials based thereon could be additionally functionalized by chemical reactions or by assembly to nanoparticles of different nature, expanding their scope of application to sensor devices, materials with antimicrobial properties. , with
    25 magnetic behavior, luminescent, etc.
    The process allows the generation of organic-inorganic hybrid composition materials with structural, textural and reactivity properties useful for various applications, such as adsorbents, thickening agents, feed additives, catalyst supports,
    30 drug supports, enzyme supports, microorganism supports, adsorbents or odor reducers, flame retardants and self-extinguishing materials, cement additives, food packaging, tissue engineering, etc., and which are also provided with additional functionalization capability by chemical reactions or by assembly to nanoparticles of different nature, which expands its scope.
    35
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    In another particular embodiment, the composite material of the invention can be subjected to chemical modifications to deliberately alter its structural and / or functional properties, particularly it can be modified by reactions with silanes, epoxides, isocyanates, dialdehydes or with any other crosslinking reagent or agent of
    5 coupling, more particularly by modifying the composite by silanization reactions of the hydroxyl functions of the material, to increase the hydrophobic nature of the composite or to confer additional reactivity.
    The third object of the invention is the use of the composite material of the invention as
    10 adsorbent or absorbent, thickening agent, feed additive, catalyst support, enzyme support, odor adsorbent, flame retardant and self-extinguishing material, cement additives, wine production, food packaging and special papers such as nano paper, between other apps.
    Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples are provided by way of illustration, and are not intended to be
    Limitations of the present invention. BRIEF DESCRIPTION OF THE FIGURES
    Figure 1: (Left) Composite material obtained after stage b) in the form of hydrogel
    Stable high viscosity produced by treatment of sepiolite and microcrystalline cellulose or microcellulose with high energy ultrasound; (Right) Mechanical mixing of sepiolite and microcrystalline cellulose that results in immediate syneresis with component separation.
    Figure 2: Images obtained by FE-SEM type microscopy showing the composite material of the invention formed from sepiolite (A) and microcrystalline cellulose (B) fibers with a 50:50 sepiolite content: microcrystalline cellulose (C).
    Figure 3: (Left) Composite material forming a stable high viscosity hydrogel 35 obtained after stage b) produced by treatment of palygorskite and microcrystalline cellulose


    with high energy ultrasound; (Right) Mechanical mixing that results in immediate syneresis with component separation.
    Figure 4: (Left) Sepiolite film: nanocellulose (ratio 34:66) submitted in the
    5 stage b) to a homogenization treatment with high energy ultrasound. (Right) Sepiolite film: nanocellulose (ratio 34:66) subjected to stage b) to a homogenization treatment using a vortex.
    Figure 5: (Above, Left) Image obtained by FE-SEM type microscopy of the material
    10 sepiolite composite: nanocellulose in 50:50 ratio, and images obtained by X-ray dispersive energy analysis (EDX) in which the material distribution of the Si and Mg elements, corresponding to the sepiolite, and of C is shown , present in the nanocellulose.
    Figure 6: FTIR spectra (3760 to 3650 cm-1 region) of sepiolite films (A),
    15 nanocellulose (B) and the composite material of the invention with a 50:50 sepiolite content: nanocellulose (C).
    Figure 7: FE-SEM image of a sepiolite composite film: nanocellulose
    50:50 integrating multipared carbon nanotubes (20% by weight with respect to the 20 content in sepiolite).
    DEMOSTRATIVE EXAMPLES OF THE INVENTION Example 1. Composite material made with microcellulose and sepiolite by sonomechanical homogenization
    In this example, the manufacturing of the composite material is illustrated, in the case that the fibrous clay is sepiolite and the microcellulose defibrated cellulose with a 50:50 ratio.
    In a volume of 10 ml of deionized water 0.2 g of sepiolite marketed by TOLSA S.A. are incorporated. as Pangel S9 with 0.2 g of microcrystalline cellulose marketed by Sigma-Aldrich (reference: 435236, CAS number 9004-34-6), mixing these components with the help of a Vortex Vibra MixR OVAN equipment for a time between 15 seconds and one minute. The resulting suspension is homogenized
    35 subjecting it to an ultrasound treatment by irradiating the mixture with 1 kJ in pulses of 10 seconds of irradiation followed by 10 seconds of rest. For irradiation 15 was used
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    A SONICS Vibracell VCX750 ultrasonic device equipped with a 13 mm diameter Al-V-Ti tip, operating at a resonance frequency of 20 kHz. The dispersion obtained is presented in the form of a thick and consistent hydrogel that remains stable for several days in the absence of syneresis against the use of mechanical mixing in stage b) of the two materials (Figure 1). The viscosity of the hydrogel measured at 25 ° C and a speed of 100 rpm with Brookfield equipment, using the small volume adapter provided with a SC4-21 spindle, is approximately 5000 cP, while the viscosities presented by the components separately, also treated with ultrasound, before mixing and under the same measurement conditions were less than 1cP (below the equipment measurement limit). Once this dispersion is dried in an oven at atmospheric pressure at 40 ° C, a compact solid of the monolithic type is collected, which constitutes the composite material of the invention. Figure 2 shows the fibrous appearance of the resulting composite material observed directly by scanning electron microscopy - field emission (FE-SEM) without metallizing treatments of the sample. Figure 2.C shows how sepiolite fibers appear homogeneously assembled in the composite.
    The infrared spectra (FTIR) of the composite material indicate the disturbance of the hydroxyl groups of the fibrous components, since they move frequently with respect to the same spectra of the starting materials before their combination. Especially the OH voltage vibrations of the sepiolite silanole groups that appear at around 3720 cm-1 disappear from the spectrum which is attributed to an interaction through hydrogen bonds that leads to a reduction in the frequency of the IR absorption bands that they move in the spectrum overlapping with other bands of greater intensity attributed to the OH vibrations of water molecules inherent in silicate (see JL Ahlrichs, et al., Clays and Clay Minerals, 23 (1975), 119; E. Ruiz- Hitzky, Journal of Materials Chemistry, 11, (2001), 86-91). This observation can be interpreted in the present case as a disturbance by interaction of the surface silanole groups of the sepiolite with the hydroxyl groups of the microcellulose fibers.
    The specific surface area (BET, N2) of the composite obtained is 160 m2 / g and the water adsorption capacity of the composite made with Quantachrome Instruments Aquadyne DVS equipment is 33%, which indicates its suitability for use as adsorbent, support of catalysts, enzymes, microorganisms, etc.
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    Example 2. Composite material made with microcellulose and paly gorskite by sonomechanical homogenization
    In this example, the manufacturing of the composite material is illustrated, in case the fibrous clay is palygorskite and the microcellulose defibrated cellulose.
    The procedure is the same as in Example 1, replacing sepiolite with palygorskite from the State of Piauí (Brazil) characterized by reference: two Santos Soares et al., Journal of Thermal Analysis and Calorimetry, 113, 2013, 551–555, until obtaining a viscous hydrogel that remains stable for several days with absence of syneresis (Figure 3). The viscosity of the hydrogel measured at 25 ° C and a speed of 100 rpm with Brookfield equipment, using the small volume adapter provided with a SC4-21 spindle, is 26.5 cP, while the viscosities presented by the components separately , also treated with ultrasound, before mixing and under the same measurement conditions were less than 1 cP (below the equipment measurement limit).
    Example 3. Composite material made with nanocellulose and sepiolite by sonomechanical homogenization
    In this example, the manufacturing of the composite material is illustrated, in case the fibrous clay is sepiolite and the defibrated cellulose is nanocellulose.
    In a volume of 10 ml of deionized water, 0.05 g of sepiolite marketed by TOLSA S.A. are incorporated. as Pangel S9 and an amount between 0.51 g and 5.1 g of a nanocellulose hydrogel from eucalyptus pulp supplied by LEPAMAP (Laboratori d'Enginyeria Paperera i Materials Polimers of the University of Girona) is added http: // lepamap. udg.edu/cat/index.htm). This cellulose is presented as a hydrogel containing approximately 1% by mass of cellulose. These components are mixed with the help of a Vortex Vibra MixR OVAN device for a time between 15 seconds and one minute. The resulting suspension is subjected to an ultrasound treatment by irradiating the mixture with 1 kJ in pulses of 10 seconds of irradiation followed by 10 seconds of rest. For irradiation, a SONICS Vibracell VCX750 ultrasonic device with a 13 mm diameter Al-V-Ti tip was used, operating at a resonance frequency of 20 kHz. The dispersion obtained is presented in the form of a consistent hydrogel that remains stable for several days with no syneresis. The viscosity of these gels measured at 25 ° C and a speed of 100 rpm with equipment
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    Brookfield, using the small volume adapter provided with a SC4-21 spindle, varies between 6.5 cP and 159 cP, while the viscosities presented by the components separately before mixing and under the same measurement conditions were < 1cP (below the equipment measurement limit) for the sepiolite dispersion treated with ultrasound and 203 cP for the 0.5% nanocellulose hydrogel (w / v) and also treated with ultrasound. Sepiolite-nanocellulose gels were formed in the form of films by vacuum filtration on a Millipore membrane (VSWP with a pore diameter of 0.025 micrometers), obtaining homogeneous films of varying thickness depending on the volume of dispersed filtration. The resulting composite material dried at atmospheric pressure at 40 ° C is presented as a very homogeneous aggregate material. Figure 4 shows two films prepared from the hydrogel containing a relative amount by weight of sepiolite: 34:66 nanocellulose, to which the sonomechanical treatment has been applied or not. Figure 5 shows the fibrous appearance of the composite material resulting from the sepiolite-nanocellulose gel with relative amounts by weight of 50:50 observed directly by scanning electron microscopy - field emission (FE-SEM) without sample metallization treatments. Also shown in the figure is the homogeneous distribution throughout the material of the elements Si and Mg, corresponding to sepiolite, and of C present in the nanocellulose fibers, obtained by X-ray dispersive energy analysis (EDX). The infrared spectra (FTIR) shown in Figure 6 indicate the disturbance of the hydroxyl groups of the fibrous components, since they move frequently with respect to them before they are combined. Especially the vibrations of tension O-H of the silanoles groups of the sepiolite that appear at around 3720 cm-1, disappear from the spectrum what is interpreted as a disturbance by interaction with the hydroxyl groups of the nanocellulose fibers.
    Example 4. Mechanical characterization of composite material that comprises nanocellulose and sepiolite prepared by sonomechanical homogenization
    In this example, several of the properties of the composite material are indicated.
    Proceed as in Example 3 but in this case combining the dispersion of sepiolite (0.4 g in 20 ml of deionized water) with 20.2 g of the nanocellulose hydrogel, homogenizing by means of a Vortex Vibra MixR OVAN equipment for 1 minute, followed by a treatment with a digital Ultra-Turrax® IKA @ T25 for 5 minutes at speed 3. The homogenization is then continued by means of ultrasonic irradiation with a SONICS Vibracell VCX750 device, operating as described in the
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    twenty
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    Example 1. The resulting composite material dried in the form of a film at atmospheric pressure at 40 ° C and relative humidity of 89% is presented as a very homogeneous aggregate material. The infrared spectra of these composites indicate a disturbance of hydroxyl groups similar to that observed in Example 3, confirming the interaction between both types of nanofibers. The films are cut in the form of strips 1.5 cm wide by 8 cm long for mechanical characterization in an Instron model 3345 universal testing equipment. Young's module of 50:50 sepiolite-nanocellulose composite films was of 1.37 GPa. This value indicates the stability and homogeneity of the material formed
    Example 5. Material c omposite made with nanocellulose and sepi olita incorporating multipared carbon nanotubes.
    This example illustrates the manufacture of ternary composite composites with improved characteristics, incorporating multipared carbon nanotubes.
    We proceed in this case by mixing 0.2 g of sepiolite in 10 ml of deionized water with 0.05 g of multipared carbon nanotubes grown by the CVD method with an average diameter of 10 nm and an average length of 1 to 2 ȝm supplied by the company Dropsens SL The mixture is subjected to an ultrasonic treatment by irradiating it until a total energy of 1 kJ is applied, in pulses of 10 seconds of irradiation followed by 10 seconds of rest, with a SONICS Vibracell VCX750 ultrasound equipment, as in Example 1. To said 2018 g of the nanocellulose hydrogel are added and, as in Example 3, a homogenization is carried out with a Vortex Vibra MixR OVAN for 1 minute. The resulting mixture is again subjected to an ultrasonic treatment as in Example 3. The resulting dispersion is filtered under vacuum on a Millipore filter (VSWP with a pore diameter of 0.025 micrometers) to obtain sepiolite composites: carbon nanotubes: nanocellulose in the proportion in weight 74: 18.5: 7.5, in the form of a film once the material has dried to constant weight in an oven at atmospheric pressure at 40 ° C. Figure 7 shows the FE-SEM image of one of these films showing the homogeneity of the three types of nanoparticles that are part of the composite material. The electrical resistance of these films determined by the van der Paw method (4-pointed method) gives an approximate value of 10 Ohms, which implies an appreciable conductivity (1.8 S / cm) for a carbon nanotube content of the 18.5% by weight (with respect to the total weight of the composite) indicated its suitability for use in electrochemical devices, such as sensors and biosensors, electrocatalysis, etc.
    权利要求:
    Claims (22)
    [1]
    image 1
    1. Composite material comprising defibrated cellulose and fibrous clay whose fibrils 5 are nanometrically bonded.
    [2]
    2. Composite material according to claim 1 characterized in that the defibrated cellulose that forms the composite material comprises microcellulose.
    3. Composite material according to claim 1 characterized in that the defibrated cellulose that forms the composite material comprises nanocellulose.
    [4]
    4. Composite material according to any of claims 1 to 3 characterized by
    that the fibrous clay is sepiolite. fifteen
    [5]
    5.  Composite material according to any of claims 1 to 4 characterized in that the fibrous clay is palygorskite.
    [6]
    6.  Composite material according to any of claims 1 to 5 characterized by
    20 that the relative amounts by weight of fibrous clay: nanocellulose are between 91: 9 and 2:98, more particularly between 50:50 and 34:66.
    [7]
    7. Composite material according to any of claims 1 to 6 characterized by
    that the relative amounts by weight of fibrous clay: microcellulose are between 40:60 and 25 60:40, more particularly in the 50:50 ratio.
    [8]
    8. Composite material according to any of claims 1 to 7 characterized in that the defibrated cellulose is of plant or microbial origin, of algae or recycled lignocellulosic residues.
    30
    [9]
    9. Preparation process of the composite material defined in claims 1 to 8, comprising the following steps: a) mixing the two fibrous components, clay and defibrated cellulose in water in the same container,
    B) strongly homogenize the mixture in the aqueous medium until a stable hydrogel is obtained.
    twenty
    image2
    [10]
    10. Method according to claim 9 wherein the starting materials are simultaneously mixed directly from commercial material or are prepared before mixing.
    5
    [11]
    eleven.  Method according to any of claims 9 to 10, wherein in step a) mechanical mixers are used to suspend the starting materials.
    [12]
    12.  Method according to any of claims 9 to 11 characterized in that
    The homogenization of stage b) is carried out by means of a high shear and pressure homogenizer, by treatment in a microfluidifier or by application of a sonomechanical treatment by means of ultrasound.
    [13]
    13. Method according to any of claims 9 to 12 wherein the
    Homogenization is performed by sonomechanical treatment using high energy ultrasound using metal tip caviters or equipment with sonotrodes.
    [14]
    14. Method according to any of claims 9 to 13 wherein the
    Homogenization is performed in static and / or continuous mode. twenty
    [15]
    15. Method according to any of claims 9 to 14 characterized in that the ultrasonic irradiation is carried out in a pulsed manner, preferably the amount of irradiated ultrasound is in a range between 100 J and 5000 J per 25 grams of dispersion, and even more preferably the ultrasound irradiation that is done so
    25 cyclic in pulses of 5 to 20 seconds of irradiation, followed by 5 to 20 seconds of rest.
    [16]
    16. Method according to any of claims 9 to 15 characterized in that
    It comprises the additional step of: 30 c) drying the stable hydrogel prepared in step b) by removing the water.
    [17]
    17. Method according to claim 16 wherein after step b) the hydrogel is shaped such that after drying in step c) it is presented in a defined form, such as monolithic blocks of predetermined dimensions, films of varying thickness, or
    35 foams of different density.
    twenty-one
    image3
    [18]
    18. Method according to any of claims 16 to 17 wherein the drying of step c) is carried out by air drying, forced extraction of water under reduced pressure, filtration, centrifugation, lyophilization, supercritical drying processes, spraying or atomization, beds fluidized or fluidized, air flow cyclone or hot inert gas.
    5
    [19]
    19. Method according to any of claims 9 to 18 characterized by incorporating organic and / or inorganic additives, to form a ternary or higher order compound based on the composite material.
    Method according to claim 19, characterized in that the inorganic additive that is incorporated is one or more of the following elements: a laminar clay or nano- or micro-metric particles of carbon nanotubes, carbon nanofibers, of a metal, of an oxide, or of a metal salt.
    A method according to claim 20 wherein carbon nanotubes are incorporated.
    [22]
    22. Method according to claim 20 wherein magnetic nanoparticles based on iron oxides of the magnetite type are incorporated.
    23. A process according to claim 19 wherein the organic additive that is incorporated is one or more of the following elements: a dye, a surfactant, or a polymeric material.
    [24]
    24. Method according to any of claims 9 to 23 wherein the material
    Composite and / or ternary or higher order materials based thereon are additionally functionalized by chemical reactions or by assembly to nanoparticles of different nature.
    [25]
    25. Method according to any of claims 9 to 24 wherein the material
    Composite is subjected to chemical modifications to deliberately alter its structural and / or functional properties, particularly it is modified by reactions with silanes, epoxides, isocyanates, dialdehydes or with any other cross-linking reagent or coupling agent, more particularly by modifying the composite by reactions of silanization of the hydroxyl functions of the material.
    35
    22
    image4
    [26]
    26. Use of the composite material defined in any one of claims 1 to 8 as absorbent, adsorbent, thickening agent, feed additive, catalyst support, enzyme support, flame retardant and self-extinguishing material, cement additives, wine production, packaging of food and special papers such as nano paper.
    2. 3
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    同族专利:
    公开号 | 公开日
    WO2016001466A1|2016-01-07|
    ES2558472B1|2016-11-16|
    引用文献:
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    PL2386683T3|2010-04-27|2014-08-29|Omya Int Ag|Process for the production of gel-based composite materials|
    FI124324B|2010-10-18|2014-06-30|Ekokem Palvelu Oy|Treatment of wood containing fraction|
    WO2013126321A1|2012-02-24|2013-08-29|Hercules Incorporated|Nanocrystalline cellulose in tape joint compound |CN108421537B|2016-07-15|2019-12-03|杭州绿一环保技术有限公司|A kind of compound adsorbent and its preparation method and application|
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    CN110921805B|2019-12-13|2021-07-16|北京化工大学|Attapulgite clay reduction-magnetic separation coupling continuous iron removal whitening purification method|
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    PCT/ES2015/070506| WO2016001466A1|2014-07-03|2015-06-30|Composite material of nanocellulose and fibrous clays, method of production and use thereof|
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