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    • 专利摘要:
    A method of producing an azo pigment is disclosed according to an illustrative embodiment of the present invention. The method includes producing slurry of the azo pigment. The slurry primarily comprises aromatic amine (PAA). The method further includes derivatization of the residual PAA in the slurry, followed by encapsulation of the slurry. The slurry is acidified or alkalized. Finally, the slurry is further processed to form PAA migration-free azo pigment. The derivatization and encapsulation synergistically reduce the PAA content, preventing migration of PAA from the pigment into a substrate on which the pigment is loaded.
    公开号:BE1023530B1
    申请号:E2016/0118
    申请日:2016-06-30
    公开日:2017-04-25
    发明作者:Vincent Devreux；Greta Verspaille；Jürgen D'haeveloose；Emmanuelle Clabaux
    申请人:Cappelle Pigments Nv；
    IPC主号:
    专利说明:

    Methods for producing azo pigments
    FIELD OF THE INVENTION
    The present invention generally relates to methods for producing azo pigments. The present invention relates more specifically to methods for producing migration-free azo pigments with primary aromatic amines (PAA).
    BACKGROUND OF THE INVENTION
    With increasing competition in the processing industry, companies are investing substantially in various packaging characteristics of edible products that are eye-catchers for their consumers. In addition to edible products, attention is also focused on packaging / appearance of other products, such as tissues, paper towels for the skin, cardboard, plastic (eg plastic toys), and so on. The desirable characteristics of the package include vividness of color, consistency of color, transparency, hue, saturation, gloss, color retention, etc. However, such a package or appearance requires the use of chemical inks, for example formulated with azo pigments. Azo pigments include certain impurities such as primary aromatic amines (PAA) that tend to migrate from the package to the product, either by permeation through the package or by deposition through contact migration. The primarily aromatic amines are present on the pigment as a residual starting material, or as a degradation product of a starting material. The combination of food type, type of printed package, ink type, contact time, contact temperature and repeated use can result in the migration of primary aromatic amines from the package into the food, potentially causing damage to the end consumer.
    Contamination of the food from the packaging by primary aromatic amines is subject to strict rules stated in Annex II, §1 of the European regulation EU / 10/2011, known as the PIM or Plastics Implementation Measure (measure for the use of plastic), which requires that plastic and multilayer plastic materials and articles that come into contact with food should not release primary aromatic amines in said food, whereby a detection limit of 0.01 mg of primary aromatic amines (aggregated) per kg of food is considered as a detection limit.
    The Swiss Government has also issued the same restrictions with regard to the migration of primary aromatic amines in the Swiss regulation SR817 023 21, in which the objective has been extended further to all food contact materials and where, for example, inks, paper, cardboard, regenerated cellulose , silicone, ... are involved
    One of the conventional ways to bypass migration of primary aromatic amines into the food is to use color indexes, ie non-azo pigments, where no primary aromatic amines are used as the starting material, and where no compounds are included that release primary aromatic amines by breakdown. Some examples of non-azo pigments include diketopyrrolopyrrole (DPP), quinoftalon, or inorganic pigments. However, such pigments often do not have the required coloristic properties found in azo pigments. For example, inorganic pigments typically have a color strength that is up to five times lower than that of azo pigments, cannot cover the wide color space as adequately as azo pigments, and typically, but not generally, have low color saturation and low transparency levels relative to azo pigments. In addition, non-azo pigments are typically more expensive than azo pigments.
    Another conventional art discloses UV-curable, low-migration inks such as SunCure (Sun Chemical Corporation). Such a method involves immobilization of all migratable impurities by means of advanced cross-linking or cross-linking. However, the method currently limits the applicability of such inks to substrates suitable for UV curing. UV-curable products are also not suitable for small packages for foods for babies and small children because the delivery of acrylic monomer, photo-initiators or other impurities to the baby food due to incomplete polymerization and subsequent curing cannot be guaranteed. In addition, UV-curable inks such as the SunCure mentioned above may be used to a limited extent in consumer items that can be heated in a microwave oven or for food products that require direct contact with the packaging material. In addition, the method described above is limited to substrate printing and has, for example, no use for mass-colored plastic such as, but not limited to, basic mixtures.
    In another instance, disclosed in WO 2005 105 928 A1, (Clariant Produkte GmbH), the production of extremely pure naphthol AS pigments has been disclosed using microreactors, followed by solvent washing and membrane microfiltration. Such a method, although it results in a low residual primary aromatic amine content, requires an adjusted set of parameters per pigment production. In addition, the method includes additional costs for production, for example, investments in micro-reactors, membranes for purification, and expenditures for ATEX equipment. The process also requires additional production time in that the process requires the execution of a few thorough steps, such as washing away agglomerates by solvent exchange, removal of traces of solvent, recovery of solvent, etc. Furthermore, said process is only specified for the production of azo pigments of the red naphthol type.
    According to another instance, as disclosed by WO 2009 129 455 A8 (Sun Chemical Corp.), an in situ synthesis of a solid solution of C.I. Pigment Yellow 13 and C.I. Pigment Yellow 83 improve the primary aromatic amine content compared to the individual synthesis of C.I. Pigment Yellow 13 and C.I. Pigment Yellow 83. However, the PAA content remains high because 370 ppm calculated as aniline versus a general tendency to lower limit 20 ppm residual primary aromatic amines on the pigment for food contact applications.
    According to yet another conventional instance, as disclosed in WO 2013 066 246 A1 (Xylophane Aktiebolag), a barrier layer may be included in the substrate to prevent migration of primary aromatic amines; this can be a functional barrier such as polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH) or an absolute barrier such as aluminum foil or a metallized plastic. An immobile topcoat barrier such as Novaset (Flint Group) can also be applied to the printed surface to eliminate contact migration by deposition. Such a barrier, however, increases the general cost price and is limited solely to the production of plastic packaging or containers of the laminated, multi-layered tetrabric type. Furthermore, as disclosed in US 5,116,649 A (Westvaco Corporation), barrier films based on EVOH show little to no adhesion to most polymers and paper, with the exception of nylon, and finally, EVOH resins are sensitive to the effects of moisture, which results in a reduced barrier performance with increasing relative humidity.
    In conclusion, the examples described show that it is difficult to obtain PAA migration-free azo pigment.
    Therefore, there is a need for the development of a method for producing azo pigments that are free from migration of PAAs that is cost effective and effective.
    Summary of the invention
    The present invention discloses a method for producing an azo pigment. The method comprises obtaining slurry from the azo pigment produced by a synthesis process followed by an optional heat treatment thereof. The slurry comprises primary aromatic amines present as an impurity of residual starting material and / or as a by-product of the synthesis process. The method further comprises the derivatization of the primary aromatic amines present in the slurry, followed by the encapsulation of the pigment present in the slurry. The slurry is then optionally made acidic or alkaline. Finally, the slurry is further processed, thereby forming an azo pigment with a very low residual PAA content. The derivatization and encapsulation synergistically reduce the PAA content, thereby minimizing the risk of migration of PAA from the pigment to a surface in contact.
    In one embodiment, a method for producing an azo pigment is provided, the method comprising: i) obtaining a slurry from the azo pigment, the slurry comprising residual primary aromatic amine (PAA); ii) derivatization of the residual PAA in the slurry; iii) encapsulation of the slurry; iv) final processing of the slurry, thereby forming a PAA migration-free azo pigment; wherein the derivatization and encapsulation synergistically reduce the PAA content, thereby preventing migration of PAA from the pigment to a surface in contact.
    The method may optionally include a step of acidifying or alkalizing the slurry. This step can be performed after step i), or after step ii, or after step iii.
    Further, the method may optionally comprise a method of working up the slurry, the method comprising the steps of filtering and washing the pigment to obtain a pigment paste, and re-slurrying the pigment paste by adding an amount of solvent ; stirring said dispersion in a temperature range between 10 ° C and 180 ° C, preferably between 15 ° C and 60 ° C until an equilibrium with respect to particle size distribution is achieved. The processing of the slurry can be carried out before step ii), or before step iii).
    In an embodiment of the present invention, derivatization of the slurry comprises adding a derivatizing agent to the slurry, wherein the derivatizing agent comprises an aldehyde, a ketone, an acyl halide, a sulfonyl halide, an organic acid anhydride, an epoxide, an epoxy wax, an isocyanate, an is (substituted) acrylic acid, a (substituted) acrylic acid ester, a (substituted) unsaturated aldehyde, a (substituted) unsaturated ketone, a (substituted) ethylene sulfonate, a lactone, a lactam, a haloalkane or a combination thereof.
    In one embodiment of the present invention, encapsulation comprises the addition of a monomer, or a series of monomers, to the encapsulation slurry.
    Such a monomer may comprise one or more functional polymerizable groups selected from a vinyl group, an unsaturated carbon group such as, but not limited to, an acrylate group, and acrylamide group, a methacrylate group, an unsaturated sulfone group, an organosilane group, a halosilane group, an organo-modified siloxane group, an isocyanate group, an epoxide group, a lactone, a lactam, or any combination thereof, or any combination thereof that results in a double layer coating.
    The series of monomers includes [A] one or more monomers bearing one or more functionalities such as, but not limited to, a haloalkane, an organic acid, an ester, an acyl chloride, an anhydride, an isocyanate, and [B] an or more monomers bearing one or more functionalities, such as an alcohol, an amine, an epoxide or any combination thereof, or any combination thereof that results in double layer coating.
    In a specific embodiment, the derivatizing agent used may be a bifunctional agent for derivatization and encapsulation.
    The acidification / alkalisation is carried out by adding an acid selected from the group of hydrogen halides with halogen in (Cl, Br, I), sulfuric acid, sulfurous acid, phosphorous acid, phosphoric acid, hypophosphorous acid, nitric acid, sulfamic acid, carboxylic acids, or organic sulfonic acids such as methanesulfonic acid or a base selected from the group of caustic soda, potassium hydroxide, lithium hydroxide, calcium hydroxide or sodium (bi) carbonate.
    The solvent used to re-slurry the pigment paste is demineralized water, an ether of a polyglycol or an ester of a polyglycol.
    Re-slurrying can be carried out in a temperature range between 10 ° C and 180 ° C, preferably between 15 ° C and 60 ° C until the particle size in equilibrium is less than 1 µm or less than 2 µm, or less than 5 pm.
    In an embodiment of the present invention, an azo-based pigment is provided, obtained by a method according to the present invention, wherein the primary aromatic amine content in the pigment is less than 20 ppm, preferably less than 10 ppm, and more preferably lower than 1 ppm.
    A pigment according to the present invention can be suitable to be incorporated in an ink in a range of 0.1-50%. Such an ink can be from, but not limited to, water-based acrylic ink, mineral ink, vegetable ink, polyamide, polyvinyl butyral, polyvinyl chloride, solvent-based nitrocellulose, cellulose acetate, or UV-curable ink to be.
    A pigment according to the present invention can be suitable for loading into a substrate.
    Such a substrate can be of, but not limited to, cellulose type such as
    Kraft / laminated / meat paper / regenerated cellulose / cardboard, or plastic such as (L) LDPE / PP / cellulose acetate / PET / PA / PVC / silicone / ..., or more specifically bonded fabric.
    Brief description of the drawings
    Other objects, features and advantages of the invention are evident from the following description when read with reference to the accompanying drawings. In the drawings, in which the same reference numbers refer to corresponding parts throughout the various views, illustrates:
    Figure 1 is a flow chart depicting a method for producing an azo pigment according to an illustrative embodiment of the present invention;
    Figure 2 is a flow chart depicting a method for producing an azo pigment according to another illustrative embodiment of the present invention; and
    Figure 3 is a flow chart depicting a method for producing an azo pigment according to yet another illustrative embodiment of the present invention;
    Detailed description of the invention
    Azo pigments are used as color indexes for packaging materials that are wrapped around edible or non-edible products. The azo pigments include primary aromatic amines that tend to migrate from the pigment to the products, thereby potentially damaging the consumer of the products. A number of methods have been developed to prevent migration; however, the methods are expensive and limit the applicability of the pigment. The present invention thus discloses methods for producing PAA migration-free azo pigments that are cost effective, environmentally friendly and time saving.
    The present invention discloses a method 100 for producing azo pigments according to an illustrative embodiment as depicted in Figure 1. Examples of azo pigments include, but are not limited to, C.I. Pigment Yellow 1, C.I. Pigment Yellow 2, C.I. Pigment Yellow 3, C.I. Pigment Yellow 4, C.I. Pigment Yellow 5, C.I. Pigment Yellow 6, C.I. Pigment Yellow 9, C.I. Pigment Yellow 10, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 16, C.I. Pigment Yellow 17, C.I. Pigment Yellow 55, C.I. Pigment Yellow 61, C.I. Pigment Yellow 62, C.I. Pigment Yellow 62: 1, C.I. Pigment Yellow 63, C.I. Pigment Yellow 65, C.I. Pigment Yellow 73, C.I. Pigment Yellow 74, C.I. Pigment Yellow 75, C.I. Pigment Yellow 81, C.I. Pigment Yellow 83, C.I. Pigment Yellow 87, C.I. Pigment Yellow 93, C.I. Pigment Yellow 94, C.I. Pigment Yellow 95, C.I. Pigment Yellow 97, C.I. Pigment Yellow 100, C.I. Pigment Yellow 104, C.I. Pigment Yellow 105, C.I. Pigment Yellow 111, C.I. Pigment Yellow 116, C.I. Pigment Yellow 120, C.I. Pigment Yellow 126, C.I. Pigment Yellow 127, C.I. Pigment
    Yellow 127: 1, C.I. Pigment Yellow 128, C.I. Pigment Yellow 130, C.I. Pigment Yellow 133, C.I. Pigment Yellow 134, C.I. Pigment Yellow 136, C.I. Pigment Yellow 150, C.I. Pigment Yellow 151, C.I. Pigment Yellow 152, C.I. Pigment Yellow 154, C.I. Pigment Yellow 155, C.I. Pigment Yellow 165, C.I. Pigment Yellow 166, C.I. Pigment Yellow 167, C.I. Pigment Yellow 168, C.I. Pigment Yellow 169, C.I. Pigment Yellow 170, C.I. Pigment Yellow 172, C.I. Pigment Yellow 174, C.I. Pigment Yellow 175, C.I. Pigment Yellow 176, C.I. Pigment Yellow 180, C.I. Pigment Yellow 181, C.I. Pigment Yellow 182, C.I. Pigment Yellow 183, C.I. Pigment Yellow 188, C.I. Pigment Yellow 190, C.I. Pigment Yellow 191, C.I. Pigment Yellow 191: 1, C.I. Pigment Yellow 194, C.I. Pigment Yellow 198, C.I. Pigment Yellow 200, C.I. Pigment Yellow 203, C.I. Pigment Yellow 204, C.I. Pigment Yellow 205, C.I. Pigment Yellow 206, C.I. Pigment Yellow 213, C.I. Pigment Orange 1, C.I. Pigment Orange 2, C.I. Pigment Orange 5, C.I. Pigment Orange 13, C.I. Pigment Orange 16, C.I. Pigment Orange 17, C.I. Pigment Orange 19, C.I. Pigment Orange 22, C.I. Pigment Orange 24, C.I. Pigment Orange 34, C.I. Pigment Orange 36, C.I. Pigment Orange 38, C.I. Pigment Orange 46, C.I. Pigment Orange 62, C.I. Pigment Orange 64, C.I. Pigment Orange 67, C.I. Pigment Orange 72, C.I. Pigment Orange 74, C.I. Pigment Orange 79, C.I. Pigment Red 2 66, C.I. Pigment Red 2 67, C.I. Pigment Red 268, C.I. Pigment Red 269, C.I. Pigment Red 273, C.I. Pigment Red 274, C.I. Pigment Red 276, C.I. Pigment Red 277, C.I. Pigment Red 278, C.I. Pigment
    Red 280, C.I. Pigment Red 281, C.I. Pigment Violet 25, C.I. Pigment Violet 32, C.I. Pigment Violet 44, C.I. Pigment Violet 50, C.I. Pigment Blue 25, C.I. Pigment Brown 1, C.I. Pigment Brown 23, C.I. Pigment Brown 25 or C.I. Pigment Brown 42.
    As shown in Figure 1, the method 100 comprises a number of steps; the sequence of the steps of the method described below are characteristic of persons skilled in the art to gain a better understanding of the invention. The method 100 starts at step 102 where slurry of azo-based pigment is obtained by an in-situ process. The slurry is preferably obtained by a process of synthesis of azo-based pigment followed by an optional heat treatment.
    According to some embodiments, the 9 slurry can be heated in a temperature range of 50 ° C to 100 ° C. There is a residual PAA content in the slurry.
    After obtaining the slurry, the process proceeds to step 104, where derivatization of the slurry is performed. The derivatization step 104 converts the undesired residual primary aromatic amines present in the slurry into non-harmful derivatives thereof. In some embodiments, the derivatization comprises adding a predetermined amount of derivatizing agent. Further, the derivatization step 104 is performed in a predetermined temperature range and at a predetermined pH level for a predetermined period of time.
    In an embodiment of the present invention, the derivatization is carried out within a temperature range of 10 to 99 C, at a pH value between 4 and 13 and for a period of time in the range between 0.01 and 4 hours.
    Derivatives product families may include, but are not limited to, aldehydes, ketones, acyl halides, sulfonyl halides, organic anhydrides, epoxides, epoxy waxes, isocyanates, isothiocyanates, (substituted) acrylic acids and their corresponding esters, (substituted) acrylamides, (substituted) unsaturated aldehydes, (substituted) unsaturated ketones, (substituted) ethylene sulfonates, haloalkanes, lactones, lactams, hydrogen peroxide, organic peroxides, sodium nitrite, phosgene, thionyl chloride, carbonyldiimidazole or any combination thereof. Acyl chlorides, sulfonyl chlorides or salts of ethylene sulfonic acid are preferably used.
    In some embodiments, the concentration of the derivatizing agent depends on the residual amount of primary aromatic amines in the vessel after synthesis of the slurry, e.g., 0.5 to 20 mole% of the derivatizing agent relative to the azo pigment. Various examples of the derivatives obtained by the derivatization step include, but are not limited to, Schiff bases, amides, sulfonamides, ethoxylated amines, carbamates, urea derivatives, deaminated amines, taurine derivatives, beta amino acids or corresponding esters by aza-Michael addition , beta-amino amides, beta-amino ketones, or any derivative combination thereof. In one example, the derivatization of an azo-based pigment slurry obtained from synthesis is carried out by bringing the slurry to pH 9 with 28% caustic soda at 40 ° C with vigorous stirring. 1% benzoyl chloride is then added to the slurry, and the pigment slurry is stirred for 1 to 4 hours at 40 ° C.
    According to some embodiments of the present invention, if the pH of the slurry in step 104 is not within the range of the predetermined pH values required for derivatization, the pH is corrected before derivatization. Therefore, a pH correction step can be performed before derivatization to obtain optimum derivatization conditions. The acidification / alkalisation is done by adding an acid selected from the group of hydrogen halides with halogen in (F, Cl, Br, I), sulfuric acid, sulfuric acid, phosphorous acid, phosphoric acid, hypophosphorous acid, nitric acid, sulfamic acid, carboxylic acids, or organic sulfonic acids such as methanesulfonic acid or a base selected from the group of caustic soda, potassium hydroxide, lithium hydroxide, calcium hydroxide or sodium (bi) carbonate.
    The method 100 proceeds to step 106 where encapsulation of the slurry is performed. In some embodiments, the encapsulation captures impurities in the slurry and can be performed by in situ polymerization. The polymerization comprises the synthesis of different polymer strands, whereby preferably a uniform shell is obtained around the pigment particle, or, in the absence of the uniform shell, a net, the apertures of which are called small so as not to pass the impurities (PAA).
    The encapsulation step comprises addition of a monomer or a series of monomers to the slurry in the presence of an initiator in a predetermined temperature range of 10 ° C to 100 ° C, preferably 30 to 60 ° C.
    A monomer may preferably comprise one or more polymerizable functional groups which may be selected from a vinyl group, an unsaturated carbon group such as an acrylate group, an acrylamide group, a methacrylate group, an unsaturated ketone, an unsaturated aldehyde, an unsaturated sulfone group, an organosilane group, a halosilane group , an organo-modified siloxane group, an epoxide group, a lactone, a lactam, or any combination thereof, or any combination thereof that results in double-layer coating.
    A series may preferably comprise [A] one or more monomers bearing one or more functional groups of the acceptor type such as, but not limited to, halogen leaving group, organic acid, ester, acyl halide, organic anhydride, sulfonyl halide, nitrile, isocyanate, isothiocyanate, ketone, aldehyde, epoxide, organosilane, halosilane, organo-modified siloxane, lactone, lactam, vinyl, and [B] include one or more monomers bearing one or more functional groups of the donor type such as, but not limited to , an alcohol, a thiol, an amine, or any combination thereof, or any combination thereof that results in double-layer coating.
    An initiator can, for example, a persulfate, a metabisulfite, a peroxide combined with a transition metal, e.g. Fe2 +, an organic peroxide, e.g. dibenzoyl peroxide, azo (bis) isobutyronitrile, or a photo initiator, e.g. bis (2,4,6-) trimethylbenzoyl) phenylphosphine oxide (IRGACURE 819).
    In some embodiments, a bifunctional agent may be used to perform both derivatization and encapsulation, the bifunctional agent [A] comprising one or more functional groups (e.g., the same functionalities as the aforementioned derivatizers) to react with the amine functionality of the primary aromatic amine, and [B] include one or more reactive monomers such as, but not limited to, the aforementioned monomers with polymerizable functional groups.
    In some embodiments, the derivatization and encapsulation process steps occur simultaneously, in that the reaction product of the primary aromatic amine with a derivatization reagent comprising a reactive functional group such as, but not limited to, a lactone, a lactam, or an epoxide, itself is the polymerization step with too much of can initiate a derivatization reagent.
    In one example, the encapsulation step 106 is performed after derivatization step 104 by first heating the slurry to 80 ° C, followed by the addition of 10% dipropylene glycol diacrylate (by weight, relative to the pigment). A solution of 10% ammonium peroxodisulfate in water is added as an initiator, followed by stirring the solution for 2 hours at 80 ° C.
    The encapsulation requires a greater amount of the monomer as compared to that of the derivatizing agent added during the derivatization step 104 relative to the weight of the azo pigment. For example, a 10 nm, homogeneous, closed shell around a 500 nm particle requires at least 12 weight percent coating. The density of the pigment defines a density of the coating.
    After performing the encapsulation, the method 100 includes optionally performing an acidification or alkalization of the slurry as indicated in step 108. The acidification or alkalization includes addition of acid or base to the slurry, respectively. Examples of acid include, but are not limited to, a hydrogen halide with halogen in (F, Cl, Br, I), sulfuric acid, phosphoric acid, sulfurous acid, phosphorous acid, hypophosphorous acid, nitric acid, sulfamic acid, carboxylic acids, or organic sulfonic acids such as, but not limited to to, methanesulfonic acid. Examples of a base include, but are not limited to, caustic soda, potassium hydroxide, lithium hydroxide, calcium hydroxide or sodium (bi) carbonate.
    The acidification is carried out to wash away traces of unreacted amine, while the alkalisation is carried out to wash away traces of unreacted coupling agent. In one case, the acidification is carried out when the pH of the slurry is lower than 2, while the alkalisation is carried out when the pH of the slurry is in the range between 10 and 12.
    The slurry is filtered during step 110. The slurry is further exposed to a washing process, thereby forming a pigment paste as shown in step 112. The washing process can be performed with tap water, purified river water, RO water, demineralized water or a combination thereof. The washing water can be acidic, neutral or corrosive. Examples of acids and bases are identical to those used in the acidification / alkalization step 108. The concentration of the acid or base is typically in the range of 0.1 to 10%, preferably 0.2 to 2%. The washing water can have a temperature range of 5 to 100 ° C. The paste is dried and finely ground to a powder in step 114 to provide a PAA migration-free azo pigment as illustrated in step 116.
    The dried pigment of the present invention can be further dispersed in an ink formulation. Such an ink can be applied to the substrate at a charge of 0.1 to 20 g of ink per m2.
    Therefore, the derivatization and encapsulation synergistically reduces the PAA content on the pigment, resulting in a range of azo pigments with a very low residual PAA content. The method disclosed herein is environmentally friendly and has a lower cost price than the examples mentioned above.
    According to some embodiments of the present invention, the present invention also discloses a method 200 for producing azo pigments. Preparation mechanisms for the steps of the method may be the same as those of the mechanism of the steps of the method 100 described above except for a few steps.
    For example, slurry preparation, derivatization, encapsulation, and final processing steps including filtering, drying, and grinding during steps 202, 212, 214, 216, and 218 are the same as steps 102-116 of method 100. However, method 200 includes execution of additional steps 204, 206, 208 and 210.
    In an embodiment of the present invention, the method may include working up the slurry by performing an optional acidification / alkalization of the slurry in step 204 to bring the residual amount of primary aromatic amine sufficiently low before washing.
    Thereafter, the worked-up slurry is filtered in step 206 followed by washing in step 208 to produce a paste of the pigment. The process proceeds to step 210 where again a slurry of the pigment is prepared. The renewed slurry of the pigment is prepared by first adding an amount of solvent to the pigment paste in a predetermined temperature range to form a dispersion. The dispersion thus formed is stirred until a balanced particle size is obtained.
    For example, after reprocessing, filtration and washing, the pigment paste is again slurried in water (city water, purified river water or RO water, or demineralised water). Other solvents can also be considered: eg glycol-based esters (see Dowanol series). Demineralized water is preferably used at 20% dry content using a high shear dispersion system at 10 to 180 ° C, preferably between 15 and 60 ° C until a balanced particle size distribution is achieved.
    The particle size of the pigment paste in equilibrium can be <5 µm, preferably <2 µm, and ideally <1 µm.
    In an embodiment of the present invention, a method 200 may be provided comprising synthesis of pigment slurry followed by optional heat treatment in step 202, and optional acidification or alkalization in step 204. Thereafter, the slurry is filtered in step 206 and washed in step 208, with characteristics and requirements identical to step 110 of method 100. The washed pigment paste is again slurried in step 210, followed by derivatization and encapsulation in steps 212 and 214, respectively. After encapsulation, the encapsulated pigment is filtered and washed, dried and finely ground in steps 216 and 218, respectively, thereby forming PAA migration-free azo pigments in step 220.
    According to some embodiments, acidification or alkalisation after encapsulation or derivatization can be prevented because the residual amount of amine is negligible after reforming slurry and derivatization / encapsulation.
    Acidification or alkalisation after derivatization / encapsulation can therefore have a negative impact on the cost price.
    According to yet another embodiment of the present invention, a method 300 for preparing azo pigments is disclosed. The mechanism of each step of the method step can be the same as the mechanism of the above-described method steps of the method 200 with the exception of the following steps. For example, slurry preparation, derivatization, encapsulation, re-preparation of slurry, pigment paste formation, and final processing steps including filtering, drying, and grinding in steps 302, 306, 314, 312, 310, 308, 316, and 318, respectively, are the same as steps 202-220 of the method 200. However, the order of the steps in the method may differ. The method 300 involves synthesis of slurry in step 302, followed by derivatization in step 304.
    After derivatization, the pigment slurry can be worked up by an optional acidification or alkalisation in step 306 to ensure that undissolved residual amine will be dissolved, after which the slurry is filtered in step 308. The slurry is washed with acid or corrosive hot water, thereby a pigment paste is formed, as indicated by step 310. The washed pigment paste is again slurried in step 312, formed by encapsulation in step 314. Thereafter, the encapsulated pigment is filtered in step 316.
    Finally, the pigment is washed, dried, and finely ground in step 318, thereby forming PAA migration-free azo pigments.
    Although the preferred embodiment of the present invention and its advantages have been disclosed in the above detailed description, the invention is not limited thereto, but solely to the object of the appended claim. As is apparent to anyone skilled in the art, the present invention can be easily produced in other specific forms without departing from its essential features. The present embodiments are, therefore, to be regarded as merely illustrative and not restrictive, the object of the invention being indicated by the claims rather than by the above description, and any additional changes must therefore also be interpreted as belonging to the objective included herein. EXAMPLE 1 (method 100):
    In the conventional state of the art, an aqueous solution of tetrazotized 3,3-dichlorobenzidine prepared from 50 parts of 3,3-dichlorobenzidine reacts at pH 4 to 6 with an aqueous solution of coupling agent prepared from 60 parts of acetylaceto-2,4-dimethylaniline and caustic soda , which results in an azo pigment slurry.
    The pH of the slurry is corrected to pH 9 with dilute sodium hydroxide and the temperature is corrected to 40 ° C. 1 part of benzoyl chloride is added to the slurry and the slurry is stirred for 1 hour at 40 ° C. 10 parts of dipropylene glycol diacrylate are added to the pigment slurry, followed by 0.3 parts of a 10% aqueous solution of ammonium peroxodisulfate in water at 40 ° C. After stirring for 2 hours at 40 ° C, the slurry is heated to 80 ° C and stirred again for 2 hours at 80 ° C.
    The resulting slurry is brought to pH 12 with a diluted solution of caustic soda and filtered. The filtered pigment paste is further washed, dried and finely ground to obtain a chemically pure C.I. Pigment Yellow 13 available. EXAMPLE 2 (METHOD 200);
    The pigment slurry from C.I. Pigment Yellow 13 after synthesis, as prepared in the above Example 1 from 50 parts of 3,3-dichlorobenzidine and 60 parts of acetylaceto-2,4-dimethylaniline, is heated to 80 ° C and brought to pH 12 with a diluted solution of caustic soda . The slurry is filtered and washed with diluted caustic soda, followed by demineralized water.
    The pigment paste is again slurried in demineralized water with a 10% dry content at 40 ° C by means of a high-shear dispersion system until a balanced particle size distribution is achieved, and the average particle size is at least lower than 5 μιη.
    The pH is adjusted to pH 9 with dilute sodium hydroxide, followed by the addition of 1 part benzoyl chloride to the slurry. The slurry is stirred for 1 hour at 40 ° C. 10 parts of dipropylene glycol diacrylate are added to the pigment slurry, followed by 0.3 parts of a 10% aqueous ammonium peroxodisulfate solution at 40 ° C. After stirring for two hours at 40 ° C, the slurry is heated to 80 ° C, and stirred for a further 2 hours at 80 ° C. The slurry is filtered, followed by washing, drying and fine grinding to a chemically pure C.I. Pigment Yellow 13 available. EXAMPLE 3 (method 300):
    The pigment slurry from C.I. Pigment Yellow 13 after synthesis as prepared in Example 1 above from 50 parts of 3,3-dichlorobenzidine and 60 parts of acetylaceto-2,4-dimethylaniline, is brought to pH 9 with dilute sodium hydroxide and the temperature is corrected to 40 ° C. 1 part of benzoyl chloride is added to the slurry and the slurry is stirred for 1 hour at 40 ° C. The slurry is heated to 80 ° C and brought to pH 12 with a diluted solution of caustic soda. The slurry is filtered and washed with diluted caustic soda, followed by demineralized water.
    The pigment paste is again slurried in demineralized water with 10% dry content at 40 ° C by means of a high-shear dispersion system until a balanced particle size distribution is achieved, and the average particle size is at least lower than 5 µm. 10 parts of dipropylene glycol diacrylate are added to the pigment slurry, followed by 0.3 parts of a 10% aqueous ammonium peroxodisulfate solution at 40 ° C. After stirring at 40 ° C, the slurry is heated to 80 ° C, and stirred for an additional 2 hours at 80 ° C. The slurry is filtered, followed by washing, drying and fine grinding to a chemically pure C.I. Pigment Yellow 13 available. EXAMPLE 4 (method 100 - derivatisation agent 2):
    The procedure of Example 1 was repeated, with the exception that 1 part of benzenesulfonyl chloride was used instead of 1 part of benzoyl chloride to produce a chemically pure C.I. Pigment Yellow 13. EXAMPLE 5 (method 100 - derivatisation agent 3):
    According to the conventional state of the art, an aqueous solution of tetrazotized 3,3-dichlorobenzidine prepared from 50 parts of 3,3-dichlorobenzidine is reacted at pH 4 to 6 with a solution of coupling agent prepared from 60 parts of acetylaceto-2,4-dimethylaniline and caustic soda , which results in an azo pigment slurry. 0.2 parts of cerium ammonium nitrate are added, followed by 1 part of maleic anhydride. The slurry is stirred for 1 hour at 40 ° C. 10 parts of dipropylene glycol diacrylate are added to the pigment slurry, followed by 0.3 parts of a 10% aqueous solution of ammonium peroxodisulfate at 40 ° C. After stirring at 40 ° C for 2 hours, the slurry is heated to 80 ° C, followed by a further 2 hours at 80 ° C.
    The resulting slurry is brought to pH 12 with a diluted solution of caustic soda, and filtered. The filtered pigment paste is further washed, dried and finely ground to obtain a chemically pure C.I. Pigment Yellow 13 available.
    权利要求:
    Claims (15)
    [1]
    CONCLUSIONS
    A method for producing an azo pigment, the method comprising the steps of i) Obtaining a slurry of the azo pigment, the slurry comprising residual primary aromatic amine (PAA); ii) derivatization of the residual PAA in the slurry; iii) encapsulation of the slurry; iv) Final processing of the slurry, thereby forming PAA migration-free azo pigment; wherein the derivatization and encapsulation synergistically reduce the PAA content, thereby preventing migration of PAA from the pigment to a surface in contact.
    [2]
    The method of claim 1, wherein the method optionally comprises an acidification and alkalization of the slurry.
    [3]
    The method of claim 1, wherein the method optionally comprises a method for working up the slurry, the method comprising the steps of filtering and washing the pigment to obtain a pigment paste, and remaking it into a slurry of the pigment paste by adding an amount of solvent; stirring said dispersion in a temperature range between 10 ° C and 100 ° C, preferably between 15 ° C and 60 ° C until a balanced particle size distribution is achieved.
    [4]
    The method of claim 3, wherein the slurry work-up is performed before step ii).
    [5]
    The method of claim 3, wherein the slurry work-up is performed before step iii).
    [6]
    The method according to any of claims 2 to 5, wherein the acidification / alkalization step is performed after step i), or after step ii) or after step iii).
    [7]
    The method of any one of claims 1 to 6, wherein the derivatization of the slurry comprises the addition of a derivatizing agent in the slurry, wherein the derivatizing agent is a haloalkane, an aldehyde, a ketone, an acyl halide, a sulfonyl halide, a organic acid anhydride, an epoxide, an epoxy wax, an isocyanate, an isothiocyanate, a (substituted) acrylic acid, a (substituted) acrylic acid ester, a (substituted) acrylamide, a (substituted) unsaturated aldehyde, a (substituted) unsaturated ketone, a ( substituted) ethylene sulfonate, a lactone, a lactam, a haloalkane, hydrogen peroxide, sodium nitrite, an organic peroxide, phosgene, thionyl chloride, carbonyl diimidazole, or any combination thereof.
    [8]
    The method of any one of claims 1 to 7, wherein encapsulation comprises the addition of a monomer, or a series of monomers, to the slurry.
    [9]
    The method of claim 8, wherein the monomer comprises one or more functional polymerizable groups selected from a vinyl group, an unsaturated carbon group such as, but not limited to, an acrylate group, an acrylamide group, a methacrylate group, an unsaturated sulfone group, an organosilane group, a halosilane group, an organo-modified siloxane group, an isocyanate group, an epoxide group, a lactone, a lactam, or any combination thereof, or any combination thereof that results in a double-layer coating, or wherein the series of monomers [A] comprises one or more monomers that carry one or more acceptor type groups such as, but not limited to, a halogen leaving group, an organic acid, an ester, an acyl halide, an organic acid anhydride, a sulfonyl halide, a nitrile, an isocyanate, an isothiocyanate, a ketone , an aldehyde, an epoxide, an organosilane, a halosilane, an organo-modified siloxane, a lactone, a lactam, a vi nyl group and [B] one or more monomers bearing one or more functional groups of the donor type, such as, but not limited to, an alcohol, a thiol, an amine, or any combination thereof, or any combination thereof that results in double-layer coating .
    [10]
    The method of any one of claims 7 to 9, wherein the derivatizing agent is a bifunctional agent for derivatization and encapsulation.
    [11]
    The method according to any of claims 2 to 10, wherein the acidification / alkalization is carried out by adding an acid selected from the group of hydrogen halides with halogen in (F, Cl, Br, I), sulfuric acid, sulfurous acid, phosphorous acid, phosphorous acid, phosphorous acid, hypophosphorous acid, nitric acid, sulfamic acid, carboxylic acids, or organic sulfonic acids such as, but not limited to, methanesulfonic acid, or a base selected from the group of caustic soda, potassium hydroxide, lithium hydroxide, calcium hydroxide or sodium (bi) carbonate.
    [12]
    The method of claim 6, wherein the re-slurrying of azo-based pigment is carried out in a temperature range between 10 ° C and 180 ° C, preferably between 15 ° C and 60 ° C to the particle size in equilibrium of the pigment paste is less than 5 μπι.
    [13]
    A pigment obtained by a method according to any one of the preceding claims, suitable for being incorporated in an ink in a range of 0.1-50% by weight relative to the ink.
    [14]
    Pigment obtained by a method according to any of claims 1 to 12, suitable for incorporation in water-based acrylic ink, ink of mineral origin, ink of vegetable origin, polyamide, polyvinyl butyral, polyvinyl chloride, on solvent-based nitrocellulose, cellulose acetate or UV-curable inks.
    [15]
    A pigment obtained by a method according to any of claims 1 to 12, suitable for loading into or onto substrate of the cellulose or plastic type, or bonded fabric, or any combination thereof or any multi-layer material of any combination that results from that.
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    同族专利:
    公开号 | 公开日
    US10508201B2|2019-12-17|
    JP6770072B2|2020-10-14|
    WO2017102739A1|2017-06-22|
    CN108603040A|2018-09-28|
    US20180362769A1|2018-12-20|
    EP3181642A1|2017-06-21|
    EP3390540A1|2018-10-24|
    CN108603040B|2020-08-18|
    JP2019502799A|2019-01-31|
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    法律状态:
    优先权:
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    EPEP15199903.4|2015-12-14|
    EP15199903.4A|EP3181642A1|2015-12-14|2015-12-14|Method for manufacturing azoic pigments|
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