superabsorbent polymers with fast absorption properties and process for producing them

专利摘要:
The present invention relates to a process for the production of a water-absorbent polymer, comprising the process steps of (i) mixing (a1) 0.1 to 99.99% by weight, preferably 20 to 98.99% by weight and more preferably 30 to 98.95% by weight of ethylenically unsaturated polymerizable monomers containing acid groups, or salts thereof, or ethylenically unsaturated polymerizable monomers containing a nitrogen protonated or quaternized, or mixtures thereof, particular preference being given to mixtures including at least ethylenically unsaturated monomers containing acidic groups, preferably acrylic acid, (a2) 0 to 70% by weight, preferably 1 to 60% by weight weight and more preferably 1 to 40% by weight of polymerised ethylenically unsaturated monomers copolymerizable with the monomers (a1), (a3) 0.001 to 10% by weight, preferably 0.01 to 7% by weight and, ma is preferably 0.01 to 5% by weight of one or more crosslinking agents, (a4) 0 to 30% by weight, preferably 1 to 20% by weight and more preferably 5 to 10% by weight weight of water-soluble polymers, (a5) 0 to 20% by weight, preferably 0.01 to 7% by weight and more preferably 0.05 to 5% by weight of one or more auxiliaries, where a sum of the weights from (a1) to (a5(...).
公开号:BR112015028304B1
申请号:R112015028304-7
申请日:2014-04-29
公开日:2021-05-18
发明作者:Laurent Wattebled；Anna Miasnikova；Markus Henn
申请人:Evonik Operations Gmbh；
IPC主号:

专利说明:

[001] The present invention refers to superabsorbent polymers with fast absorption properties and process for producing them.
[002] The current trend in diaper construction is the production of increasingly thinner constructions, with reduced cellulose fiber content and higher superabsorbent content. The advantage of thinner constructions is not only greater wearing comfort, but also reduced packaging and storage costs. With the trend towards increasingly thinner diaper constructions, the profile of requirements for super absorbents has changed significantly. Of crucial importance is now the ability of the hydrogel to conduct and distribute the liquid. Due to the greater amount of charge of the sanitary article (amount of superabsorbent per unit area), the polymer in the swollen state should not form a barrier layer for the subsequent liquid (gel blocking). If the product has good transport properties, an optimal use of the general hygiene article can be ensured.
[003] In addition to the permeability of superabsorbent (SAP) (reported in the form of what is called "Saline Flow Conductivity - SFC - Saline Flow Conductivity") and the absorption capacity in compressive effort, the absorption rate of particles superabsorbents in particular (reported as the amount of liquid absorbed per gram of superabsorbent material per second) is also an essential criterion, which allows for statements about whether an absorbent core, which comprises a high concentration of this superabsorbent and has only a low content of fluff material it is capable, on its first contact with liquids, of absorbing them quickly (called "acquisition"). In the case of absorbent cores with a high superabsorbent content, this "acquisition" depends, among other factors, on the absorption rate of the superabsorbent material.
[004] In the prior art, there are several known property rights that supposedly allow an increase in the rate of absorption of superabsorbent particles. WO96/17884A1 describes a water-absorbent resin, in which a solid blowing agent is used in the monomer solution, with a particle diameter of 1 to 100 µm. In principle, preference is given to organic azo compounds and here specifically to acrylic salts of azo compounds containing an amino group. Pure carbonates, ammonium nitride or their mixtures can optionally be used.
[005] The disadvantages here are the rapid conversion of the azo compounds and the basic dispersion of the small solid particles in the monomer solution. Larger particles cannot be dispersed well without separating the particles and solving the monomer in the dispersion before it reaches the gel point.
[006] A disadvantage here, in the case of using superabsorbent materials known from the prior art, is that leakage problems occur, since the SAP either absorbs the liquid very slowly and/or transports the liquid inappropriately.
[007] The current trend, particularly in diaper construction, is to produce even thinner absorbent cores with reduced cellulose fiber content and higher superabsorbent content. The advantage of thinner constructions is not only greater wearing comfort, but also reduced packaging and storage costs. The latest generation of absorbent cores, which is described, for example, in WO-A-2008/155722, WO-A-2008/155,711, WO-A-2008/155,710, WO-A-2008/155702, WO -A-2008/155701, WO-A-2008/155699, EP-A-1 225 857, WO-A-01/15647, WO-A-2011/120504, DE-A-10 2009 049 450, WO- A-2008/117109, WO-A-97/11659, EP-A-0 826 349, WO-A-98/37846, WO-A-95/11653, WO-A-95/11651, WO-A- 95/11652, WO-A-95/11654, WO-A-2004/071363 or WO-A-01/89439, is essentially cellulose free (this is why corresponding diapers are also referred to as "fluffless diapers" or "nappies without plush material"). The immobilization of superabsorbent particles, which in absorbent cores containing cellulose is performed by cellulose fibers, in this new generation of absorbent cores can be achieved, for example, by immobilizing the superabsorbent particles on a substrate surface by means of thermoplastic fibers.
[008] With the trend towards increasingly thinner diaper constructions and the lack of the temporary liquid conduction and storage function of cellulose fibers, the profile of requirements for superabsorbents has changed significantly. Now, a crucially important factor is the hydrogel's ability to prevent the leakage of urine directly into urination. This is achieved by the property of the superabsorbent/hydrogel to effectively absorb the liquid during swelling and distribute it in the gel layer, while minimizing the amount of unbound urine in the diaper. Due to the good transport properties, the advantageous superabsorbents also allow the optimal use of the general hygiene article.
[009] The document US 5,154,713 describes water-absorbent polymers that are prepared by means of a carbonate blowing agent in the monomer solution. Here, the carbonate particles are introduced into the monomer solution well before the actual polymerization and the initiator is added from 5 to 15 minutes after the dispersion of the carbonate blowing agent, with the result that the homogeneous distribution of these particles is not ensured. carbonate and a considerable part of the carbonate can be discharged again. EP 0 644 207 describes superabsorbent polymers which are likewise mixed with an organic carbonate blowing agent in the monomer solution. Here the disadvantages are the use of amine compounds and also the permanence of the organic carbonate scavenging products in the superabsorbent.
[010] WO 2010/095427 describes water-absorbent polymers, in which a gas is dispersed in the monomer solution. This gas is nitrogen, argon, helium, carbon dioxide or the like, which are intended to ensure a more porous structure. The intention is to keep these microbubbles in the monomer solution using polyoxyethylene (20) sorbitan monostearate, until polymerization occurs. The downside here is that surfactants can be washed out of the final product again and negatively affect performance.
[011] A crucially important factor is the ability of the hydrogel to prevent urine leakage directly into urination. This is achieved by the property of the superabsorbent/hydrogel to effectively absorb the liquid during swelling and distribute it in the gel layer, while minimizing the amount of unbound urine in the diaper. Due to the good transport properties, the advantageous superabsorbents also allow the ideal use of the general hygiene article.
[012] The term "rewetting" is generally understood to mean the property of a superabsorbent, or a composite comprising a superabsorbent, to release liquid into an absorbent layer when subjected to compressive stress. The term "absorbent layer" is understood to mean, for example, paper, filter paper, collagen, sponges, foams or the like. EP1858998B1 discloses superabsorbent foams, where the monomer solution gives rise to a foam only at a high pressure of 12 bar, through the addition of carbon dioxide and surfactants.
[013] However, the prior art superabsorbents known to date are unsuitable for use in the new generation of cell-free diaper constructions described above.
[014] In general, it is an object of the present invention to overcome the disadvantages arising from the prior art.
[015] More particularly, it is an object of the present invention to provide a process for the production of a water-absorbent polymer, which has an improved swelling rate and a faster absorption of liquids, while maintaining the overall quality and more particularly, a high permeability.
[016] It is also an additional object to carry out the process in an economically simple way, with the intention of minimizing the use of organic additives and also providing a mode of operation at ambient pressure.
[017] It is a particular object of the present invention to provide a process by which water-absorbent polymers can be produced and a particularly high swelling rate can be ensured.
[018] It is yet another object of the present invention to provide, in addition, a process by which it is possible to produce water-absorbent polymers that ensure the fast and active transport of liquid, for example, in thin diapers, in such a way that they are ensured rapid absorption and good distribution, ie corresponding capillarity.
[019] It is yet another object of the present invention, in particular, to specify a water-absorbent polymer, composites comprising such water-absorbent polymers and chemicals comprising such polymers or water-absorbent composites, the water-absorbent polymers having a greater capacity for absorption for aqueous solutions.
[020] These objects are achieved by the matter of category-forming claims. Advantageous configurations and developments which can occur individually or in combination form the subject of the dependent claims in each case.
[021] The contribution to the realization of the object referred to at the beginning is made by the process for the production of a water-absorbent polymer, which comprises the mixing process steps from (1) 0.1 to 99.999% by weight, preferably , 20 to 98.99% by weight and more preferably 30 to 98.95% by weight of ethylenically unsaturated polymerizable monomers containing acidic groups, or salts thereof, or ethylenically unsaturated polymerizable monomers including a protonated or quaternized nitrogen, or mixtures of these, particular preference being given to mixtures including at least ethylenically unsaturated monomers containing acidic groups, preferably acrylic acid,
[022] (2) 0 to 70% by weight, preferably 1 to 60% by weight and more preferably 1 to 40% by weight of ethylenically unsaturated polymerizable monomers, copolymerizable with the monomers (1),
[023] (3) 0.001 to 10% by weight, preferably 0.01 to 7% by weight and more preferably 0.01 to 5% by weight of one or more crosslinking agents,
[024] (4) 0 to 30% by weight, preferably 1 to 20% by weight and more preferably 5 to 10% by weight of water-soluble polymers,
[025] (5) 0 to 20% by weight, preferably 0.01 to 7% by weight and more preferably 0.05 to 5% by weight of one or more auxiliaries, where the sum of the weights of (1) to (5) is 100% by weight,
[026] (ii) free radical polymerization with crosslinking to form an untreated, water-insoluble, aqueous hydrogel polymer,
[027] (iii) drying the hydrogel polymer,
[028] (iv) milling and sieving the hydrogel polymer to size,
[029] (v) post-surface crosslinking of ground and sieved hydrogel polymer and
[030] (vi) drying and finishing of the water-absorbent polymer,
[031] in which
[032] the aqueous monomer solution, before the addition of the initiator and the start of free radical polymerization, is mixed with 0.01 to 5% by weight, preferably 0.02 to 2% by weight and more than preferably 0.07 to 1% by weight of at least one surfactant from the group of non-ionic unsaturated polyether copolymers and optionally 0.01 to 5% by weight, preferably 0.02 to 2% by weight and, more preferably, 0.07 to 1% by weight of a blowing agent having a particle size of 10 µm to 900 µm, based on the water-absorbent polymer.
[033] The term "water-absorbent polymer" is understood, according to the invention, to mean superabsorbent.
[034] Another embodiment relates to a process for the production of a water-absorbent hydrogel polymer, comprising the process steps of
[035] mixture of
[036] (1) 0.1 to 99.99% by weight, preferably 20 to 98.99% by weight and more preferably 30 to 98.95% by weight of ethylenically unsaturated polymerizable monomers containing acidic groups, or salts thereof, or ethylenically unsaturated polymerizable monomers including a protonated or quaternized nitrogen, or mixtures thereof, with particular preference being given to mixtures including at least ethylenically unsaturated monomers containing acidic groups, preferably acrylic acid,
[037] (2) 0 to 70% by weight, preferably 1 to 60% by weight and more preferably 1 to 40% by weight of ethylenically unsaturated polymerizable monomers, copolymerizable with the monomers (1),
[038] (3) 0.001 to 10% by weight, preferably 0.01 to 7% by weight and more preferably 0.01 to 5% by weight of one or more crosslinking agents,
[039] (4) 0 to 30% by weight, preferably 1 to 20% by weight and more preferably 5 to 10% by weight of water-soluble polymers,
[040] (5) 0 to 20% by weight, preferably 0.01 to 7% by weight and more preferably 0.05 to 5% by weight of one or more auxiliaries, where the sum of the weights of (1) to (5) is 100% by weight,
[041] (ii) free radical polymerization with crosslinking to form an untreated, water-insoluble, aqueous hydrogel polymer,
[042] (iii) drying the hydrogel polymer,
[043] (iv) grinding and sieving the water-absorbent polymer to size,
[044] where
[045] the aqueous monomer solution, before the addition of the initiator and the start of free radical polymerization, is mixed with 0.01 to 5% by weight, preferably 0.02 to 2% by weight and more than preferably 0.07 to 1% by weight of at least one surfactant from the group of non-ionic unsaturated polyether copolymers and optionally 0.01 to 5% by weight, preferably 0.02 to 2% by weight and more preferably 0.07 to 1% by weight of a blowing agent having a particle size of 10 µm to 900 µm, based on the hydrogel polymer.
[046] This hydrogel polymer of the invention can be converted, by means of thermally induced post-crosslinking, into a water-absorbent polymer (superabsorbent) of the invention.
[047] Preference is given, according to the invention, in ensuring that the surfactants are polymerized in the polymer network. Advantageously, this greatly reduces the amount of extractable surfactant constituents and therefore only minimally reduces the surface tension.
[048] According to the invention, the addition of surfactants and blowing agents to the monomer solution after polymerization obtains a fine porous gel structure and provides superabsorbent powders that have a larger surface area. Advantageously, according to the invention, the increase in the general surface area ensures a faster absorption of the liquid, compared to conventional SPAs. This is demonstrated by the so-called FSR value. The water-absorbent polymers of the invention have an FSR value in the range of from 0.30 to 0.70, preferably from 0.35 to 0.60, more preferably from 0.40 to 0.50.
[049] According to the invention, despite the use of surfactants, the surface tension is in the range above 50 mN/m, preferably above 55 mN/m, more preferably above 60 mN/m, still more preferably, above 65 mN/m. According to the invention, the surface tension is not greater than 71 mN/m.
[050] According to the invention, the permeability, which is referred to as the SFC value (in the present invention always based on 1.5 g) of the water-absorbent polymer composition, is in the range of 30 to 200, of preferably from 50 to 180 and more preferably in the range from 70 to 150.
[051] According to the invention, the PSD particle size distribution of the hydrogel polymer is such that more than 60% of the particles are in the range of 300 µm to 600 µm and less than 5% of the particles are smaller than 150 µm.
[052] In the case of low surface tension, this usually causes an increase in rewetting values, eg rewetting of the backsheet, or leakage in diapers in which such superabsorbents are used. Advantageously, this problem is avoided by the process according to the invention, in the form of the surfactants which can be incorporated by polymerization. In addition, superabsorbents perform well with respect to retention (CRC) and absorption (AAP) against pressure.
[053] Adapted surfactants are added to the monomer solution to produce the inventive superabsorbents. These specific surfactants contain functional groups that are polymerizable. According to the invention, these are unsaturated polyether copolymers formed from relatively hydrophilic ethylene glycol units and relatively hydrophobic alkylene glycol units having 3 to 6 carbon atoms. Unsaturated polyethers can comprise, in combination with ethylene glycol units, one or more units other than alkylene glycol. Preference is given to propylene glycol (for example 1,2- or 1,3-propanediol), butylene glycol (for example 1,2-, 1,3- or 1,4-butanediol), pentylene glycol (for example 1, 5-pentanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,3-pentanediol, 2,4-pentanediol or 2,5-pentanediol) or hexylene glycol (for example, 1,6- hexanediol). Alkylene glycol units can be distributed randomly, in blocks or as a gradient in the surfactant. In the context of the present invention, the individual alkylene glycol units can be isotactic, syndiotactic or atactic sequences of configuration in the molecule.
[054] degree of polymerization of the polyether structure in the surfactant is generally in the range of 2 to 100, preferably in the range of 4 to 50, more preferably in the range of 6 to 20. The degrees of alkoxylation declared if refer each to the average degree of alkoxylation. Naturally, the preparation generally results in mixtures in which lower and higher oligomers can additionally be present.
[055] unsaturated group can be a vinyl ether, methyl(allyl ether), 4-vinylbenzyl ether, (meth)acrylamide, methacrylic ester or acrylic ester groups and are preferably at the end of the chain.
[056] Polymerizable surfactants that can be used are also copolymer esters of polyether and ethacrylic acid, a-chloroacrylic acid, a-cyanoacrylic acid, β-methylacrylic acid (crotonic acid), a-phenylacrylic acid, e-acryloyloxypropionic acid, sorbic acid, a-chlorosorbic acid, 2'-methylisocrotonic acid, cinnamic acid, p-chlorocinnamic acid, β-stearyl acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaric acid, maleic anhydride and tricarboxyethylene.
[057] In addition, it is possible to use copolymer esters of polyether and allylsulfonic acid or aliphatic or aromatic vinylsulfonic acids or acrylic or methacrylic sulfonic acids, where examples of aliphatic or aromatic vinylsulfonic acids used are vinylsulfonic acid, 4- vinylbenzylsulfonic acid, vinyltoluenesulfonic acid or styrenesulfonic acid, acryloyl- or methacryloylsulfonic acid, acids of the sulfoethyl(meth)acrylate group, sulfopropyl(meth)acrylate, 2-hydroxy-3-methacryloyloxypropylsulfonic acid, (meth)acrylamidoalkylsulfonic acids of the acid group 2- acrylamido-2-methylpropanesulfonic acid, phosphonic acid monomers from the vinylphosphonic acid group, allylphosphonic acid, vinylbenzylphosphonic acid, (meth)acrylamidoalkylphosphonic acids, acrylamidoalkyldiphosphonic acids, phosphonomethylated vinylamines and derivatives of (meth)acryloylphosphonic acid, or acrylamides from the (methacrylamides) group substituted alkyl meth)acrylamides or amine derivatives (meth)acrylamide substituted inoalkyls from the N-methylol(meth)acrylamide group, vinylamides from the N-vinylamides group, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl-N-methylformamide.
[058] At the other end of the polyether chains there is a hydroxyl group, a hydroxyl group etherified with an organyl radical R-, or the hydroxyl group esterified with an acyl radical of general structure R-(C=O)-, where the organyl radical R- is a C1- to C10-alkyl group or a C6- to C10-alkylaryl group and may be linear or branched. Preference is given to a hydroxyl group, a hydroxyl group etherified with methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, 2-methylbutyl, 2,2-dimethylpropyl and also n-hexyl, n- heptyl, n-octyl, n-nonyl, n-decyl or the isomers of these radicals as alkyl radicals.
[059] Particular preference is given to surfactants of the following formula:

[060] in which the alkylene glycol units (C2H4O) and (CqH2qO) can be randomly distributed, in blocks or as a gradient and
[061] R1 is -H or -CH3,
[062] R2 is a -C=O- group or an alkylene group of the methylene and ethylene group,
[063] R3 is -H, C- to C9-alkyl or C6- to C9-alkylaryl linear or branched,
[064] p = 0 or 1,
[065] q is a number from 3 to 4 and
[066] n and m are each a number from 1 to 20.
[067] Particular preference is given to random or gradient structures, for example, hydroxy-functional surfactants, such as Blemmer®50PEP-300 (polyalkylene glycol monomethacrylate; 3.5 ethylene glycol units and 2.5 propylene glycol units), and Blemmer®55PET-800 (polyalkylene glycol monomethacrylate; 10 ethylene glycol units and 5 butylene glycol units).
[068] In another preferred embodiment, block structures are used, for example, Blemmer®70PEP-350B (polyalkylene glycol monomethacrylate; 5 ethylene glycol units and 2 end propylene glycol units), all supplied by NOF Corporation (Japan) .
[069] In addition, for block copolymers, examples of polymerizable surfactants that have an alkyl ether radical are listed below: methoxy polyalkylene glycol mono(meth)acrylate (6 ethylene glycol units and 6 end propylene glycol units; both as 7) .5 ethylene glycol units and 3 end propylene glycol units) and butoxy-polyalkylene glycol mono(meth)acrylate (4 propylene glycol units and 7 end ethylene glycol units) from Evonik Industries AG.
[070] In another embodiment, the allylic surfactants can also be present in a random structure, for example, monoallyl ether polyalkylene glycol (7 units of ethylene glycol and 3 units of propylene glycol) (PE8482 Evonik Industries AG).
[071] Blowing agents used can be all carbonates of the lithium carbonate group, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, or higher valence metal ions such as beryllium carbonate, carbonate of calcium, magnesium carbonate, strontium carbonate or mixtures thereof. Additional compounds used can also be granulated carbonates, which are also produced in the form of mixed salts of a carbonate and/or percarbonate with another salt, which functions as an outer layer, for example a sulfate compound. According to the invention, the blowing agents have a particle size from 10 µm to 900 µm, preferably from 50 µm to 500 µm and more preferably from 100 µm to 450 µm. The carbonate compounds can be used in powder form or in the form of an aqueous solution thereof.
[072] According to the invention, surfactants are generally used simultaneously with the crosslinking agent. In one embodiment, the blowing agent is added after adding the surfactant. In other embodiments, the blowing agent can be supplied at the same time as or before the surfactant.
[073] By the addition of blowing agents or sodium carbonate small bubbles are formed, which have a smaller diameter in the presence of surfactants.
[074] According to the invention, the surfactants stabilize the large surface area of the gas that appears in solution through the blowing agent. The polymerization, which takes place in parallel, is fixed in a fine porous structure (porous gel). Surfactants are "inactivated" during polymerization, meaning that they can be incorporated into the polymer network or are incorporated due to their reactive functionality.
[075] Advantageously, the synergy observed between the surfactants and blowing agents allows the use of smaller amounts of blowing agent, for example, carbonate. Typical disadvantages associated with carbonates include the possible difficulties in mixing and adding to the solution and uncontrolled dispersion of the small bubbles formed, for example, significant coalescence or excessively large bubbles, or the loss of other SAP properties.
[076] Monoethylenically unsaturated monomers (1) containing acid groups can be partially or fully neutralized, preferably partially. Preferably, the monoethylenically unsaturated monomers containing acidic groups are neutralized to an extent of at least 10 mol%, more preferably to an extent of 25 to 90 mol% and even more preferably to an extent of 50 to 80 % mol. Neutralization of monomers (1) can precede or otherwise follow polymerization. In this case, partial neutralization is carried out to an extent of at least 10 mol%, more preferably to an extent of 25 to 90 mol%, and even more preferably to an extent of 50 to 80 mol%. In addition, neutralization can be carried out with alkali metal hydroxides, alkaline earth metal hydroxides, ammonia and carbonates and bicarbonates. Furthermore, any other base which forms a water-soluble salt with the acid is conceivable. Mixed neutralization with different bases is also conceivable. Preference is given to neutralizing with ammonia or alkali metal hydroxides, more preferably with sodium hydroxide or ammonia.
[077] In addition, free acid groups may predominate in a polymer, such that this polymer has a pH in the acidic range. This acidic water-absorbent polymer can be at least partially neutralized by a polymer with free basic groups, preferably amine groups, which are basic to the acidic polymer. These polymers are referred to in the literature as "Mixed-Bed Ion Exchange Absorbent Polymers" (Mixed-Bed Ion-Exchange Absorbent Polymers - MBIEA polymers) and are disclosed in WO 99/34843, among others. The disclosure of WO 99/34843 is incorporated herein by reference and is therefore considered to be part of this disclosure. In general, MBIEA polymers constitute a composition that includes, firstly, the base polymers capable of exchanging anions and, secondly, a polymer that is acidic compared to the base polymer and is capable of exchanging cations. The basic polymer has basic groups and is typically obtained by polymerizing monomers that have basic groups or groups that can be converted to basic groups. These monomers are, in particular, those which have primary, secondary or tertiary amines or the corresponding phosphines, or at least two of the above functional groups. This group of monomers especially includes ethyleneamine, allylamine, diallylamine, 4-aminobutene, alkyloxycyclines, vinylformamide, 5-aminopentene, carbodiimide, formdacine, melamine and the like and the secondary or tertiary amine derivatives thereof.
[078] Monoethylenically unsaturated monomers (1) containing acidic groups are acrylic acid, methacrylic acid, ethacrylic acid, α-chloroacrylic acid, a-cyanoacrylic acid, β-methylacrylic acid (crotonic acid), a-phenylacrylic acid, β- acid acryloyloxypropionic acid, sorbic acid, a-chlorosorbic acid, 2'-methylisocrotonic acid, cinnamic acid, p-chlorocinnamic acid, e-stearyl acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaric acid, maleic anhydride and tricarboxyethylene, particular preference being given to acrylic acid and methacrylic acid and, in addition, to acrylic acid.
[079] In addition to these monomers containing carboxylate groups, preferred monoethylenically unsaturated monomers (1) containing acid groups additionally include ethylenically unsaturated sulfonic acid monomers or ethylenically unsaturated phosphonic acid monomers.
[080] Preferred ethylenically unsaturated sulfonic acid monomers are allylsulfonic acid or aliphatic or aromatic vinylsulfonic acids or acrylic or methacrylic sulfonic acids. Preferred aliphatic or aromatic vinyl sulfonic acids are vinyl sulfonic acid, 4-vinylbenzylsulfonic acid, vinyltoluenesulfonic acid, and styrenesulfonic acid. Preferred acryloyl or methacryloylsulfonic acids are sulfoethyl(meth)acrylate, sulfopropyl(meth)acrylate, 2-hydroxy-3-methacryloyloxypropylsulfonic acid and (meth)acrylamidoalkylsulfonic acids such as 2-acrylamido-2-methylpropane acid - sulfonic.
[081] Preferred ethylenically unsaturated phosphonic acid monomers are vinylphosphonic acid, allylphosphonic acid, vinylbenzylphosphonic acid, (meth)acrylamidoalkylphosphonic acids, acrylamidoalkyldiphosphonic acids, phosphonomethylated vinylamines and (meth)acryloylphosphonic acid derivatives.
[082] Preferred ethylenically unsaturated monomers (1) containing a protonated nitrogen atom are preferably dialkylaminoalkyl (meth)acrylates in protonated form, for example, dimethylaminoethyl(meth)acrylate hydrochloride or dimethylaminoethyl(meth)acrylate sulfhydrate. dimethylaminoethyl and dialkylaminoalkyl(meth)acrylamides in protonated form, for example dimethylaminoethyl(meth)acrylamide hydrochloride, dimethylaminopropyl(meth)acrylamide hydrochloride, dimethylaminopropyl(meth)acrylamide sulfhydrate or dimethylaminoethyl(meth)acrylamide sulfhydrate.
[083] Preferred ethylenically unsaturated monomers (1) containing a quaternized nitrogen atom are dialkylammonioalkyl(meth)acrylates in quaternized form, e.g. trimethylammonioethyl(meth)acrylate or dimethylethylammonioethyl(meth)acrylate and (meth)acrylamidoalkyldimethosulfate quaternized form, for example (meth)acrylamidopropyltrimethylammonium chloride, trimethylammonioethyl(meth)acrylate chloride or (meth)acrylamidopropyltrimethylammonium chloride.
[084] Preferred monoethylenically unsaturated monomers (2) copolymerizable with (1) are acrylamides and methacrylamides.
[085] Preferred (meth)acrylamides are, in addition to acrylamide and methacrylamide, alkyl substituted (meth)acrylamides or substituted aminoalkyl derivatives of (meth)acrylamide, such as N-methylol(meth)acrylamide, N,N-dimethylamino(meth )acrylamide, dimethyl(meth)acrylamide or diethyl(meth)acrylamide. Possible vinylamides are, for example, N-vinylamide, N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl-N-methylformamide, vinylpyrrolidone. Among these monomers, particular preference is given to acrylamide.
[086] Additionally, preferred as monoethylenically unsaturated monomers (2) copolymerizable with (1) are water-dispersible monomers. Preferred water-dispersible monomers are acrylic esters and methacrylic esters, such as methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate or butyl(meth)acrylate and also vinyl acetate, styrene and isobutylene.
[087] Preferred cross-linking agents (3), according to the invention, are compounds with at least two ethylenically unsaturated groups within a molecule (class I cross-linkers), compounds with at least two functional groups that can react with functional groups of monomers (1) or (2) in a condensation reaction (= condensation crosslinking agents), in an addition reaction or in a ring opening reaction (class II crosslinking agents), compounds having at least one ethylenically unsaturated group and at least one functional group that can react with functional groups of the monomers (1) or (2) in a condensation reaction, in an addition reaction or in a ring opening reaction (crosslinking agents class III), or polyvalent metal cations (class IV crosslinking agents). Class I crosslinking agent compounds achieve polymer crosslinking by free radical polymerization of the ethylenically unsaturated groups of the crosslinking agent molecule with monoethylenically unsaturated monomers (1) or (2), whereas class crosslinking agent compounds II and the polyvalent metal cations of class IV crosslinking agents achieve polymer crosslinking by a condensation reaction of functional groups (class II crosslinking agents) or by electrostatic interaction of the polyvalent metal cation (class IV crosslinking agents) with the functional groups of the monomers of (1) or (2). In the case of class III crosslinking agent compounds, there is corresponding crosslinking of the polymer, either by free radical polymerization of the ethylenically unsaturated group or by condensation reaction between the functional group of the crosslinking agent and the functional groups of the monomers (1) or (two).
[088] Preferred class I crosslinking agent compounds are poly(meth)acrylic esters which are obtained, for example, by the reaction of a polyol, eg ethylene glycol, propylene glycol, trimethylolpropane, 1,6-hexanediol, glycerol, pentaerythritol polyethylene glycol or polypropylene glycol, an amino alcohol, a polyalkylenepolyamine, for example diethylenetriamine or triethylenetetramine, or a polyol alkoxylated with acrylic acid or methacrylic acid. Preferred class I crosslinking agent compounds are, in addition, polyvinyl compounds, poly(meth)allyl compounds, (meth)acrylic esters of a monovinyl compound, or (meth)acrylic esters of a mono(meth)allyl compound, of preferably, mono(meth)allylic compounds of a polyol or an amino alcohol. In this context, reference is made to DE 195 43 366 and DE 195 43 368. The disclosures are incorporated herein by reference and therefore are considered to be part of this disclosure.
[089] Examples of class I crosslinking agent compounds include alkenyl di(meth)acrylates, for example, ethylene glycol di(meth)acrylate, 1,3-propylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate )acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,18-octadecanediol di(meth)acrylate, cyclopentanediol di(meth)acrylate, neopentylglycol di(meth)acrylate, methylene di(meth)acrylate or pentaerythritol di(meth)acrylate, alkenyl di(meth)acrylamides eg N-methyl di(meth) )acrylamide, N,N'-3-methylbutylidene-bis(meth)acrylamide, N,N'-(1,2-dihydroxyethylene)-bis(meth)acrylamide, N,N'-hexamethylene-bis(meth)acrylamide or N,N'-methylenebis(meth)acrylamide, polyalkoxy di(meth)acrylates, e.g. diethyleneglycol di(meth)acrylate, triethyleneglycol di(meth)acrylate, tetraethyleneglycol di(meth)acrylate, dipropyleneglycol di(meth)acrylate, tripropyleneglycol di(meth)acrylate or tetrapropylene glycol di(meth) )acrylate, bisphenol A di(meth)acrylate, bisphenol A di(meth)acrylate ethoxylate, benzylidene di(meth)acrylate, 1,3-di(meth)acryloyloxy-2-propanol, hydroquinone di(meth)acrylate, esters of trimethylolpropane di(meth)acrylate which has been preferably alkoxylated, preferably ethoxylated, with 1 to 30 moles of alkylene oxide per hydroxyl group, thioethylene glycol di(meth)acrylate, thiopropylene glycol di(meth)acrylate, thiopolyethylene glycol di(meth) acrylate, thiopolypropylene glycol di(meth)acrylate, divinyl ethers, for example, 1,4-butanediol divinyl ether, divinyl esters, for example, divinyl adipate, alkadienes, for example, butadiene or 1,6-hexadiene, divinylbenzene, di(meth)allyl compounds, eg di(meth)allyl phthalate or di(meth)allyl succinate, di(meth)allyl-dimethylammonium chloride homopolymers and copolymers, and ammonium chloride homopolymers and copolymers of diethyl(meth)allylaminomethyl (meth)acrylate, (meth)acryloyl vinyl compounds, e.g. (meth)acryl vinyl act, (meth)allyl(meth)acryloyl compounds, for example (meth)allyl(meth)acrylate, ethoxylated (meth)allyl(meth)acrylate with 1 to 30 mol of ethylene oxide per hydroxyl group, esters of di(meth)allyl of polycarboxylic acids, for example, di(meth)allyl maleate, di(meth)allyl fumarate, di(meth)allyl succinate or di(meth)allyl terephthalate, compounds with 3 or more groups ethylenically unsaturated, free radical polymerizable, eg glyceryl tri(meth)acrylate, glycerol(meth)acrylate esters which have been ethoxylated preferably with 1 to 30 mol of ethylene oxide per hydroxyl group, tri(meth) trimethylolpropane acrylate, trimethylolpropane tri(meth)acrylate esters which have been preferably alkoxylated, preferably ethoxylated, with 1 to 30 mol of alkylene oxide per hydroxyl group, trimethacrylamide, (meth)allylidene di(meth)acrylate, 3 -allyloxy-1,2-propanediol di(meth)acrylate, tri(meth)allyl cyanurate, tri(meth)isocyanurate, pentaerythritol tetra(meth)acryl to, pentaerythritol tri(meth)acrylate, (meth)acrylic esters of ethoxylated pentaerythritol, preferably with 1 to 30 mol of ethylene oxide per hydroxyl group, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, trivinyl trimellitate, tri(meth)allylamine, di(meth)allyl-alkylamines, e.g., di(meth)allyl-methylamine, tri(meth)allyl phosphate, tetra(meth)allyl-ethylenediamine, poly(meth)allyl esters, tetra (meth)allyloxyethane or tetra(meth)allylammonium halides.
[090] Compounds Preferred class II crosslinking agents are compounds having at least two functional groups that can react in a condensation reaction (= condensation crosslinking agents), in an addition reaction or in a ring opening reaction with the functional groups of the monomers (1) or (2), preferably with acid groups of the monomers (1). These functional groups of class II crosslinking agent compounds are preferably alcohol, amine, aldehyde, glycidyl, isocyanate, carbonate or epichloro functions.
[091] Examples of class II crosslinking agent compounds include polyols, for example, ethylene glycol, polyethylene glycols such as diethylene glycol, triethylene glycol and tetraethylene glycol, propylene glycol, polypropylene glycols such as dipropylene glycol, tripropylene glycol or tetrapropylene glycol, 1,3-butanediol, 1, 4-butanediol, 1,5-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 2,5-hexanediol, glycerol, polyglycerol, trimethylolpropane, polyoxypropylene, oxyethylene-oxypropylene block copolymers, sorbitan fatty acid esters , fatty acid esters of polyoxyethylene sorbitan, pentaerythritol, sorbitol and polyvinyl alcohol, amino alcohols, for example, ethanolamine, diethanolamine, triethanolamine or propanolamine, polyamine compounds, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine or pentaethylenehexamine, compounds polyglycidyl ether such as ethylene glycol diglycidyl ether, polyethyl diglycidyl ether enoglycol, glyceryl diglycidyl ether, glyceryl polyglycidyl ether, pentaerythritol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentylglycol diglycidyl ether, hexanediol glycidyl ether, polyglycidyl ether triglycidyl ether, polyglycidyl ether triglycidyl ether , diglycidyl adipate, 1,4-phenylenebis(2-oxazoline), glycidol, polyisocyanates, preferably diisocyanates such as 2,4-toluene diisocyanate and hexamethylene diisocyanate, polyaziridine compounds such as 2,2-bis- hydroxymethylbutanol tris[3-(1-aziridinyl)propionate], 1,6-hexamethylenediethylene-urea and diphenylmethane-bis-4,4'-N,N'-diethyleneurea, halogen peroxides, eg epichloro and epibromidrine and -methylepichlorohydrin , alkylene carbonates such as 1,3-dioxolan-2-one (ethylene carbonate), 4-methyl-1,3-dioxolan-2-one (propylene carbonate), 4,5-dimethyl-1,3 -dioxolan-2-one, 4,4-dimethyl- 1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1,3-dioxan-2-one, 4- methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one, poly-1,3-dioxolan-2-one, polyquaternary amines such as condensation products of dimethylamines and epichlorohydrin. Preferred class II crosslinking agent compounds are additionally polyoxazolines such as 1,2-ethylenebisoxazoline, crosslinking agents with silane groups such as Y-glycidoxypropyltrimethoxysilane and Y-aminopropyltrimethoxysilane, oxazolidinones such as 2-oxazolidinone, bis- and poly-2-oxazolidinones and diglycol silicates.
[092] Preferred class III compounds include hydroxyl or amine containing esters of (meth)acrylic acid, for example 2-hydroxyethyl(meth)acrylate and 2-hydroxypropyl(meth)acrylate and also (meth)acrylamides containing hydroxyl or amine groups or mono(meth)allylic diol compounds.
[093] The polyvalent metal cations of class IV crosslinking agents are preferably derived from mono or polyvalent cations, the monovalent ones especially from alkali metals such as potassium, sodium, lithium, with preference given to lithium. Preferred divalent cations are derived from zinc, beryllium, alkaline earth metals such as magnesium, calcium, strontium, with preference given to magnesium. Other cations with higher valence which can be used according to the invention are the cations of aluminum, iron, chromium, manganese, titanium, zirconium and other transition metals and also the double salts of such cations or mixtures of the salts mentioned. Preference is given to the use of aluminum salts and aluminates and their different hydrates, for example, AICI3 x 6H2O, NaAl(SO4)2 x 12 H2O, KAl(SO4)2 x 12 H2O or Al2(SO4)3x14-18 H2O . Particular preference is given to the use of Al2(SO4)3 and hydrates thereof as class IV crosslinking agents.
[094] The superabsorbent particles used in the process according to the invention are preferably cross-linked by cross-linking agents of the following classes, or by cross-linking agents of the following combinations of classes of cross-linking agents: I, II, III, IV, I II, I III, I IV, I II III, I II IV, I III IV, II III IV, II IV or III IV. The above combinations of classes of crosslinking agents are each a preferred embodiment of the superabsorbent particle crosslinking agents used in the process according to the invention.
[095] Other preferred embodiments of the superabsorbent particles used in the process according to the invention are polymers which are cross-linked by any of the class I cross-linking agents. Among these, preference is given to water-soluble cross-linking agents. In this context, particular preference is given to N,N'-methylene-bis-acrylamide, polyethylene glycol di(meth)acrylates, triallylmethylammonium chloride, tetralylammonium chloride, and allyl nonaethylene glycol acrylate prepared with 9 moles of ethylene oxide per mole of acrylic acid.
[096] As water-soluble polymers (4), superabsorbent particles can comprise water-soluble polymers, such as partially or fully hydrolyzed polyvinyl alcohol, polyvinylpyrrolidone, starch or starch derivatives, polyglycols or polyacrylic acid, preferably incorporated into the form polymerized. The molecular weight of these polymers is not critical as long as they are water soluble. Preferred water-soluble polymers are starch or starch derivatives or polyvinyl alcohol. Water-soluble polymers, preferably synthetic water-soluble polymers, such as polyvinyl alcohol, can also serve as a graft base for the monomers to be polymerized.
[097] The auxiliaries (5) present in the polymers are organic or inorganic particles, for example, odor binders, especially zeolites or cyclodextrins, skin care substances, surfactants or antioxidants.
[098] Preferred organic auxiliaries include cyclodextrins or derivatives thereof and polysaccharides. Also preferred are cellulose and cellulose derivatives such as CMC, cellulose ethers. Preferred cyclodextrins or cyclodextrin derivatives are the compounds disclosed in DE-A-198 25 486 on page 3, line 51, through page 4, line 61. The above mentioned section of this published patent application is incorporated herein by reference and, therefore, it is considered to be part of the disclosure of the present invention. Particularly preferred cyclodextrins are non-derivatized -, -, - or δ-cyclodextrins.
[099] The particulate inorganic auxiliaries used can be any materials that are typically used to modify the properties of water-absorbent polymers. Preferred inorganic auxiliaries include sulfates such as Na 2 SO 4 , lactates, for example sodium lactate, silicates, especially structured silicates such as zeolites, or silicates which have been obtained by drying aqueous silica solutions or colloidal silica solutions, for example commercially available products such as precipitated silicas and fumed silicas, for example Aerosils having a particle size in the range of 5 to 50 nm, preferably in the range of 8 to 20 nm, such as "Aerosil 200" from Evonik Industries AG, aluminates, titanium dioxides, zinc oxides, clay materials and other minerals familiar to those skilled in the art and also carbonaceous inorganic materials.
[100] Preferred silicates are all natural or synthetic silicates which are disclosed as silicates in Hollemann and Wiberg, Lehrbuch der Anorganischen Chemie [Inorganic Chemistry], Walter de Gruyter-Verlag, 91st and 100th edition, 1985, at pages 750 to 783. The section of this book mentioned above is incorporated herein by reference and is considered to be part of the disclosure of the present invention.
[101] Particularly preferred silicates are zeolites. The zeolites used can be all synthetic or natural zeolites known to those skilled in the art. The preferred natural zeolites are zeolites of the natrolite group, harmotome group, mordenite group, chabazite group, faujasite group (sodalite group) or analcite group. Examples of natural zeolites are analcima, leucite, polucite, wairaquita, belbergite, bikitaite, boggsite, brewsterite, chabazite, willhendersonite, cowlesite, dachiardita, edingtonite, epistilbite, erionite, faujasite, gonnarynitism, gironita, amicite , goosecroquite, harmotome, philipsite, wellsite, clinoptilolite, heulandite, laumontite, levynite, mazzite, merlinoite, montesommaite, mordenite, mesolite, natrolite, scolecite, offretite, paranatrolite, paulingite, perichilia, stilbyrita, estelbitarita . Preferred synthetic zeolites are zeolite A, zeolite X, zeolite Y, zeolite P, or the ABSCENTS® product.
[102] The zeolites used can be zeolites of the so-called "intermediate" type, in which the SiO2/AlO2 ratio is less than 10; the SiO2/AlO2 ratio of these zeolites is most preferably in the range of 2 to 10. In addition to these "intermediate" zeolites, it is also possible to use "high" type zeolites, which include, for example, the zeolites known as " molecular sieves" of the ZSM and -zeolite type. These "high" zeolites are preferably characterized by a SiO2/AlO2 ratio of at least 35, more preferably by a SiO2/AlO2 ratio in the range of 200 to 500.
[103] Preferably used aluminates are naturally occurring spinel, especially common spinel, zinc spinel, iron spinel or chromium spinel.
[104] Preferred titanium dioxide is pure titanium dioxide in the crystalline forms rutile, anatase and brookite and also iron-containing titanium dioxides, eg ilmenite, calcium-containing titanium dioxides, such as titanite or perovskite.
[105] Preferred clay materials are those disclosed as clay materials in Hollemann and Wiberg, Lehrbuch der Anorganischen Chemie, Walter de Gruyter-Verlag, 91st and 100th edition 1985, on pages 783 to 785. In particular, the section of this book mentioned above is incorporated herein by reference and is considered to be part of the disclosure of the present invention. Particularly preferred clay materials are kaolinite, illite, halloysite, montmorillonite and talc.
[106] Other preferred inorganic fines according to the invention are metal salts of mono, oligo and polyphosphoric acids. Among these, preference is especially given to hydrates, with particular preference being given to monohydrates to decahydrates and trihydrates. Useful metals especially include alkali metals and alkaline earth metals, with preference given to alkaline earth metals. Among these, Mg and Ca are preferred and Mg is particularly preferred. In the context of phosphates, phosphoric acids and metallic compounds thereof, reference is made to Hollemann and Wiberg, Lehrbuch der Anorganischen Chemie, Walter de Gruyter-Verlag, 91st-100th edition 1985, on pages 651 to 669. The section of this book mentioned above. is incorporated herein by reference and is considered to be part of the disclosure of the present invention.
[107] Preferred carbonaceous but non-organic auxiliaries are those pure carbons which are mentioned as graphites in Hollemann and Wiberg, Lehrbuch der Anorganischen Chemie, Walter de Gruyter-Verlag, 91st-100th edition 1985, on pages 705 to 708. The section of this book mentioned above is incorporated herein by reference and is considered to be part of the disclosure of the present invention. Particularly preferred graphites are synthetic graphites, for example coke, pyrographite, activated carbon or carbon black.
[108] The water-absorbent polymers obtained in the process according to the invention are preferably obtained primarily by preparing a hydrogel polymer (PC) in particulate form from the above-mentioned monomers and crosslinking agents. This starting material for the water-absorbent polymers is produced, for example, by bulk polymerization, which is preferably carried out in kneading reactors, such as extruders, by solution polymerization, by spray polymerization, by emulsion polymerization inverse or by inverse suspension polymerization. Preference is given to carrying out the solution polymerization using water as a solvent. Solution polymerization can be carried out continuously or discontinuously (batch). The state of the art reveals a wide spectrum of possible variations with respect to the reaction conditions, such as temperature, type and amount of initiators and the reaction solution. Typical processes are described in the following patents: US 4,286,082, DE 27 06 135, US 4,076,663, DE 35 03 458, DE 40 20 780, DE 42 44 548, DE 43 23 001, DE 43 33 056, DE 44 18 818. The disclosures are incorporated herein by reference and, therefore, are considered to be part of this disclosure.
[109] The initiators used to initiate polymerization can be all initiators that form free radicals under polymerization conditions and are commonly used in the production of superabsorbents. These include thermal initiators, redox initiators and photoinitiators, which are activated through high energy radiation. Polymerization initiators can be present dissolved or dispersed in a solution of the monomers of the invention. Preference is given to the use of water soluble initiators.
[110] Useful thermal initiators include all compounds that decompose to free radicals when heated and are known to those skilled in the art. Particular preference is given to thermal polymerization initiators having a half-life of less than 10 seconds, even more preferably less than 5 seconds at less than 180°C, even more preferably at less than 140°C. Peroxides, hydroperoxides, hydrogen peroxide, persulfates and azo compounds are particularly preferred thermal polymerization initiators. In some cases, it is advantageous to use mixtures of different thermal polymerization initiators. Among these mixtures, preference is given to those of hydrogen peroxide and sodium peroxodisulfate or potassium peroxodisulfate, which can be used in any conceivable proportion. Suitable organic peroxides are preferably acetylacetone peroxide, methyl ethyl ketone peroxide, benzoyl peroxide, lauroyl peroxide, acetyl peroxide, capryla peroxide, isopropyl peroxydicarbonate, 2-ethylhexyl peroxydicarbonate, t-butyl hydroperoxide , cumene hydroperoxide, t-amyl perpivalate, t-butyl perpivalate, t-butyl perneohexanoate, t-butyl-isobutyrate, t-butyl-per-2-ethylhexanoate, t-butyl perisononanoate, t-butyl permaleate , t-butyl perbenzoate, t-butyl 3,5,5-trimethylhexanoate and amyl perneodecanoate. Other preferred thermal polymerization initiators are: azo compounds such as azobis-isobutyronitrile, azobis-dimethylvaleronitrile, 2,2'-azobis(2-amidinopropane dihydrochloride), azobis-amidinopropane dihydrochloride, 2,2'-azobis(N) dihydrochloride ,N-dimethylene)isobutyramidine, 2-(carbamoylazo)isobutyronitrile and 4,4'-azobis(4-cyanovaleric acid). The compounds mentioned are used in customary amounts, preferably in a range from 0.01 to 5 mol%, preferably from 0.1 to 2 mol%, based in each case on the amount of monomers to be polymerized.
[111] Redox initiators comprise, as the oxidic component, at least one of the per-specified compounds above and as the reducing component, preferably ascorbic acid, glucose, sorbose, mannose, hydrogensulfite, sulfate, thiosulfate, hyposulfite or ammonium sulfide, alkali metal hydrogensulfite, sulfate, thiosulfate, hyposulfite or sulfide, metal salts such as iron(II) ions or silver ions, or sodium hydroxymethylsulfoxylate. The reducing component used in the redox initiator is preferably ascorbic acid or sodium pyrosulfite. Based on the amount of monomers used in the polymerization, 1x10-5 to 1 mol% of the reducing component of the redox initiator and 1x10-5 to 5 mol% of the oxidizing component of the redox initiator are used. Instead of or in addition to the oxidizing component of the redox initiator, it is possible to use one or more azo compounds, preferably water-soluble.
[112] If polymerization is triggered by the action of high-energy radiation, it is customary to use so-called photoinitiators as an initiator. These can be, for example, so-called splitters, H-removal systems, or azides. Examples of such initiators are benzophenone derivatives such as Michler's ketone, phenanthrene derivatives, fluorene derivatives, anthraquinone derivatives, thioxanthone derivatives, coumarin derivatives, benzoin ethers and their derivatives, azo compounds such as radical formers free mentioned above, substituted hexaryl bisimidazoles or acylphosphine oxides. Examples of azides are: 2-(N,N-dimethylamino)ethyl-4 azidocinnamate, 2-(N,N-dimethylamino)ethyl-4 azidonaphthylketone, 2-(N,N-dimethylamino)ethyl-4-azidobenzoate, 5- azido-1-naphthyl 2'-(N,N-dimethylamino)ethyl sulfone, N-(4-sulfonylazidophenyl)maleimide, N-acetyl-4-sulfonylazidoaniline, 4-sulfonylazidoaniline, 4-azidoaniline, 4-azidophenacyl bromide, acid p-azidobenzoic, 2,6-bis(p-azidobenzylidene)cyclohexanone and 2,6-bis(p-azidobenzylidene)-4-methylcyclohexanone. If used, photoinitiators are generally used in amounts of 0.01 to 5% by weight, based on the monomers to be polymerized.
[113] Preference is given, according to the invention, to using an initiator system consisting of hydrogen peroxide, sodium peroxodisulfate and ascorbic acid. In general, polymerization is initiated with initiators over a temperature range of 0 °C to 90 °C.
[114] The polymerization reaction can be triggered by an initiator or by a plurality of interacting initiators. Furthermore, the polymerization can be carried out in such a way that one or more redox initiators are added first. Later in the polymerization, thermal initiators or photoinitiators are then additionally applied and the polymerization reaction, in the case of photoinitiators, is started by the action of high energy radiation. The reverse sequence, that is, the initiation of the reaction by means of high-energy radiation and photoinitiators or thermal initiators and the initiation of polymerization by means of one or more redox initiators later in the polymerization, is also conceivable.
[115] To convert the hydrogel polymers (PC) thus obtained to a particulate form, first, after they have been removed from the reaction mixture, they can be dried at a temperature in the range of 20 to 300 °C, preferably , in the range of 50 to 250 °C and more preferably in the range of 100 to 200 °C, up to a water content of less than 40% by weight, preferably less than 20% by weight and even more than preferably less than 10% by weight, based in each case on the total weight of the hydrogel polymer (PC). Drying is preferably carried out in ovens or dryers known to those skilled in the art, for example, in belt dryers, stage dryers, rotary tube ovens, fluidized bed dryers, tray dryers, paddle dryers or dryers. infra-red.
[116] According to the present invention, comminution is preferably carried out by dry milling, preferably by dry milling in a hammer mill, a fixed disk mill, a ball mill or a roller mill . In another version of the present invention, the hydrogel polymer can also be ground by combinations of two or more of the mills described above.
[117] In a preferred embodiment of the processes according to the invention, the water-absorbent polymers obtained are particles having an inner region and a surface region bordering the inner region. The surface region has a different chemical composition than the inner region, or differs from the inner region in one physical property. Physical properties in which the inner region differs from the surface region are, for example, charge density or degree of crosslinking.
[118] These water-absorbent polymers that have an inner region and a surface region bordering the inner region are preferably obtained by post-crosslinking the reactive groups near the surface of the particulate hydrogel polymer (PC) particles. This post-crosslinking can be performed thermally, chemically or photochemically.
[119] Preferred post-crosslinking agents are the class II and IV crosslinking agent compounds mentioned in connection with the crosslinking agents (3).
[120] Among these compounds, particularly preferred post-crosslinking agents are diethylene glycol, triethylene glycol, polyethylene glycol, glycerol, polyglycerol, propylene glycol, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymers, sorbitan fatty acid esters, esters of polyoxyethylenesorbitan fatty acids, trimethylolpropane, pentaerythritol, polyvinyl alcohol, sorbitol, 1,3-dioxolan-2-one (ethylene carbonate), 4-methyl-1,3-dioxolan-2-one (propylene carbonate), 4, 5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1, 3-dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one, 1,3 -dioxolan-2-one, poly-1,3-dioxolan-2-one.
[121] Particular preference is given to the use of ethylene carbonate as a post-crosslinking agent. Preferred embodiments of the water-absorbent polymers are those which are post-crosslinked by crosslinking agents of the following classes, or by crosslinking agents of the following combinations of crosslinking agent classes: II, IV and II IV.
[122] post-crosslinking agent is preferably used in an amount in the range of 0.01 to 30% by weight, more preferably in an amount in the range of 0.1 to 20% by weight, and furthermore more preferably, in an amount in the range of 0.3 to 5% by weight based in each case on the weight of the superabsorbent polymers in the post-crosslinking.
[123] It is also preferred that post-crosslinking is carried out by contacting a solvent preferably comprising water, water-miscible organic solvents, for example methanol or ethanol or mixtures of at least two of these and the post-crosslinking agent. crosslinking with the outer region of the hydrogel polymer particles at a temperature in the range from 30 to 300 °C, more preferably from 100 to 200 °C. Contacting is preferably carried out by spraying the mixture consisting of post-crosslinking agent and solvent onto the hydrogel polymer particles and then mixing the hydrogel polymer particles in contact with the mixture. The post-crosslinking agent is preferably present in the mixture in an amount in the range of 0.01 to 20% by weight, more preferably in an amount in the range of 0.1 to 10% by weight, based on the total weight of the mixture. Additionally, it is preferred that contacting the hydrogel polymer particles is carried out in an amount in the range of 0.01 to 50% by weight, more preferably in an amount in the range of 0.1 to 30% by weight, with based in each case on the total weight of the hydrogel polymer particles.
[124] Useful condensation reactions preferably include the formation of ester, amide, imide or urethane bonds, with preference given to the formation of ester bonds.
[125] The hydrogel polymers and/or water-absorbent polymers of the invention can additionally be mixed with other additives and effect substances.
[126] Preferred additives are additional release agents, eg inorganic or organic powdery release agents. These release agents are preferably used in amounts in the range of 0 to 2% by weight, more preferably in the range of 0.1 to 1.5% by weight, based on the weight of the hydrogel polymer and/ or the water absorbent polymer. Preferred release agents are: wood flour, cellulose fibers, powdered tree bark, cellulose powder, mineral fillers such as perlite, synthetic fillers such as nylon powder, rayon powder, diatomaceous earth, bentonite, kaolin, zeolites, talc, marl, ash, coal dust, magnesium silicates, fertilizers or mixtures of these substances. Finely divided fumed silica as sold under the trade name Aerosil by Evonik Degussa is preferred.
[127] In another preferred embodiment of the process according to the invention, the hydrogel polymer particles and/or the water-absorbent polymer particles are brought into contact with an effect substance, for example a polysugar, a polyphenolic compound, for example hydrolyzable tannins or a silicon-oxygen-containing compound, or a mixture of at least two active substances based on these. The effect substance can be added either in solid form (powder) or in the form dissolved in a solvent, such effect substance being added after process step (iii) and not before. In the context of the present invention, an effect substance is understood to mean a substance that serves to inhibit odor.
[128] According to the invention, this is understood to mean polysugars, which a person skilled in the art understands to be substances from the group of starches and their derivatives, celluloses and their derivatives, cyclodextrins. Cyclodextrins are preferably understood to mean -cyclodextrin, -cyclodextrin, -cyclodextrin or mixtures of these cyclodextrins.
[129] The preferred silicon-oxygen containing compounds are zeolites. The zeolites used can be all synthetic or natural zeolites known to those skilled in the art. The preferred natural zeolites are zeolites of the natrolite group, harmotome group, mordenite group, chabazite group, faujasite group (sodalite group) or analcite group. Examples of natural zeolites are analcima, leucite, polucite, wairaquita, belbergite, bikitaite, boggsite, brewsterite, chabazite, willhendersonite, cowlesite, dachiardita, edingtonite, epistilbite, erionite, faujasite, gonnarynitism, gironita, amicite , goosecroquite, harmotome, philipsite, wellsite, clinoptilolite, heulandite, laumontite, levynite, mazzite, merlinoite, montesommaite, mordenite, mesolite, natrolite, scolecite, offretite, paranatrolite, paulingite, perichilia, stilbyrita, estelbitarita . Preferred synthetic zeolites are zeolite A, zeolite X, zeolite Y, zeolite P, or the ABSCENTS® product.
[130] The cations present in the zeolites used in the process according to the invention are preferably alkali metal cations such as Li+, Na+, K+, Rb+, Cs+ or Fr+ and/or alkaline earth metal cations such as Mg2+ , Ca2+, Sr2+ or Ba2+.
[131] The zeolites used can be zeolites of the so-called "intermediate" type, in which the SiO2/AlO2 ratio is less than 10; the SiO2/AlO2 ratio of these zeolites is most preferably in the range of 2 to 10. In addition to these "intermediate" zeolites, it is also possible to use "high" type zeolites, which include, for example, the so-called "sieve" zeolites molecular structures" of the ZSM and -zeolite type. These "high" zeolites are preferably characterized by a SiO2/AlO2 ratio of at least 35, more preferably by a SiO2/AlO2 ratio in the range of 200 to 500.
[132] Zeolites are preferably used in the form of particles with an average particle size in the range of 1 to 500 µm, more preferably in the range of 2 to 200 µm and even more preferably in the range of 5 to 100 µm.
[133] The effect substances are used in the processes according to the invention preferably in an amount in the range of 0.1 to 50% by weight, more preferably in an amount in the range of 1 to 40% by weight and even more preferably in an amount in the range of 5 to 30% by weight, based in each case on the weight of the hydrogel polymer particles and/or water-absorbent polymer particles.
[134] Preferred microbe inhibiting substances are, in principle, all substances active against Gram-positive bacteria, eg 4-hydroxybenzoic acid and its salts and esters, N-(4-chlorophenyl)-N'-(3, 4-dichlorophenyl)urea, 2,4,4'-trichloro-2'-hydroxydiphenyl ether (triclosan), 4-chloro-3,5-dimethylphenol, 2,2'-methylenebis(6-bromo-4-chlorophenol), 3-methyl-4-(1-methylethyl)phenol, 2-benzyl-4-chlorophenol, 3-(4-chlorophenoxy)-1,2-propanediol, 3-iodo-2-propynylbutyl carbamate, chlorhexidine, 3,4, 4'-trichlorocarbanilide (TTC), antibacterial fragrances, thymol, thyme oil, eugenol, clove oil, menthol, spearmint oil, farnesol, phenoxyethanol, glyceryl monocaprate, glyceryl monocaprylate, glyceryl monolaurate (GML), glyceryl monocaprate diglyceryl (DMC), N-alkylsalicyamides, for example Nn-octylsalicylamide or Nn-decylsalicylamide.
[135] Suitable enzyme inhibitors are, for example, esterase inhibitors. These are preferably trialkyl citrates such as trimethyl citrate, tripropyl citrate, triisopropyl citrate, tributyl citrate and especially triethyl citrate (Hydagen TM CAT, Cognis GmbH, Dusseldorf, Germany). The substances inhibit enzyme activity and, as a result, reduce odor formation. Other substances useful as esterase inhibitors are sterol sulfates or phosphates, for example lanosterol sulfate or phosphate, cholesterol sulfate or phosphate, campesterol sulfate or phosphate, stigmasterol sulfate or phosphate, and sitosterol sulfate or phosphate, dicarboxylic acids and its esters, for example, glutaric acid, monoethyl glutarate, diethyl glutarate, adipic acid, monoethyl adipate, diethyl adipate, malonic acid and diethyl malonate, hydroxycarboxylic acids and their esters, for example, citric acid, malic acid, tartaric acid or diethyl tartrate and zinc glycinate.
[136] Suitable odor absorbers are substances that can substantially absorb and retain odor-forming compounds. They reduce the partial pressure of the individual components and thus also reduce their propagation speed. It is important that perfumes must remain intact. Odor absorbers have no effect against bacteria. They contain as a main constituent, for example, a complex zinc salt of ricinoleic acid or specific substantially odor neutralizing fragrances known to one skilled in the art as "fixers", e.g. extracts of labdane or Styrax or particular derivatives of abietic acid. The function of odor maskers is fulfilled by odorants or perfume oils, which in addition to their function as odor maskers, convey their particular fragrance note to deodorants. Examples of perfume oils include mixtures of natural and synthetic odorous substances. Natural odorants are extracts from flowers, stems and leaves, fruits, fruit peels, roots, wood, herbs and grasses, buds and branches, as well as resins and balms. Additionally useful are raw materials of animal origin, for example civet and castoro. Typical synthetic odorant compounds are ester, ether, aldehyde, ketone, alcohol and hydrocarbon type products. Ester-type odorant compounds are, for example, benzyl acetate, p-tert-butylcyclohexyl acetate, linalyl acetate, phenylethyl acetate, linalyl benzoate, benzyl formate, allyl cyclohexylpropionate, styralyl propionate and benzyl salicylate. Ethers include, for example, ethyl benzyl ether; aldehydes include, for example, linear alkanals having 8 to 18 carbon atoms, citral, citronellal, citronelliloxyacetaldehyde, cyclamen aldehyde, hydroxycitronellal, lilial and bourgeonal; ketones include, for example, the ionones and cedryl methyl ketone; alcohols include anethole, citronellol, eugenol, isoeugenol, geraniol, linalool, phenyl ethyl alcohol and terpineol; hydrocarbons primarily include terpenes and balsams. Preference is given, however, to the use of mixtures of different odorous substances which together produce a pleasant fragrance note. Suitable perfume oils are also relatively low volatility essential oils, which are normally used as flavor components, eg sage oil, chamomile oil, clove oil, Melissa oil, spearmint oil, cinnamon leaf oil , lime flower oil, juniper berry oil (Juniperberry), vetiver oil, frankincense oil, galbanum oil, labdane oil and lavender oil. Preference is given for the use of bergamot oil, dihydromyrcenol, lilyal, liral, citronellol, phenyl ethyl alcohol, alpha-hexylcinnamaldehyde, geraniol, benzylacetone, cyclamen aldehyde, linalool, Boisambrene Forte, ambroxan, indole, Hedione, Sandelice, lemon oil , mandarin oil, orange oil, allyl amyl glycolate, cyclovertal, lavender oil, sage oil, beta-damascone, geranium oil, cyclohexyl salicylate, Vertofix Coeur, Iso-E-Super, Fixolide NP, Evernyl, gamma iraldein, phenylacetic acid, geranyl acetate, benzyl acetate, rose oxide, Romilat, Irotyl and Floramat, alone or in mixtures.
[137] Antiperspirants reduce sweat formation by influencing the activity of the eccrine sweat glands and thereby preventing underarm moisture and body odor. Astringent antiperspirant active ingredients are, in particular, aluminum, zinc or zirconium salts. Such suitable anti-hydrotic active ingredients are, for example, aluminum chloride, aluminum hydrochloride, aluminum dihydrochloride, aluminum sesquihydrochloride and their complexes, for example with 1,2-propylene glycol, aluminum hydroxyalantoinate, aluminum chloride tartrate. aluminum, aluminum zirconium trihydrochloride, aluminum zirconium tetrahydrochloride, aluminum zirconium pentahydrochloride and their complexes, for example with amino acids such as glycine.
[138] Apparatus suitable for mixing or spraying is any one which permits the homogeneous distribution of a solution, powder, suspension or dispersion on or with the hydrogel polymer (PC) or water absorbing polymer particles. Examples are Lodige mixers (manufactured by Gebrüder Lodige Maschinenbau GmbH), Gericke multi-flow mixers (manufactured by Gericke GmbH), DRAIS mixers (manufactured by DRAIS GmbH Spezialmaschinenfabrik Mannheim), Hosokawa mixers (Hosokawa Mokron Co., Ltd.), Ruberg mixers ( manufactured by Gebr. Ruberg GmbH & Co. KG Nieheim), Hüttlin coaters (manufactured by BWI Hüttlin GmbH Steinen), fluid bed dryers or AMMAG spray granulators (manufactured by AMMAG Gunskirchen, Austria) or Heinen (manufactured by A. Heinen AG Anlagenbau Varel), Patterson-Kelly mixers, NARA paddle mixers, screw mixers, tray mixers, fluid bed dryers or Schugi mixers. For contact in a fluidized bed, it is possible to employ all fluidized bed processes which are known to those skilled in the art and which appear to be suitable. For example, it is possible to use a fluid bed coater.
[139] Another contribution to the solution of the problems described initially is made by a composite including the water-absorbent polymers or hydrogel polymers of the invention, or the water-absorbent polymers or hydrogel polymers that can be obtained by the processes according to with the invention and a substrate. It is preferred that the water-absorbent polymers or hydrogel polymers of the invention and the substrate are fixedly bonded together. Preferred substrates are polymer films, for example polyethylene, polypropylene or polyamide, metals, nonwovens, terry cloth, tissue, fabric, natural or synthetic fibers, or foams. It is further preferred, according to the invention, that the composite comprises at least one region which includes water-absorbent polymers or hydrogel polymers in an amount in the range from 15 to 100% by weight, preferably from 30 to 100 % by weight, more preferably from 50 to 99.99% by weight, even more preferably from 60 to 99.99% by weight and even more preferably from 70 to 99% by weight, based on in each case, on the total weight of the region of the composite in question, this region preferably having a size of at least 0.01 cm3, preferably of at least 0.1 cm3 and more preferably of at least 0.5 cm3.
[140] Another contribution to the solution of at least one of the problems indicated initially is made by a process for the production of a composite, in which the water-absorbent polymers of the invention or the superabsorbers obtainable by the process according to the invention are a substrate and, optionally, an additive are brought into contact with each other. The substrates used are preferably those substrates which have already been mentioned above in connection with the composite of the invention.
[141] A contribution to the solution of at least one of the problems indicated initially is also made by a composite obtained by the process described above, such composite preferably having the same properties as the composite of the invention described above.
[142] Another contribution to the solution of at least one of the problems indicated initially is made by chemicals, including water absorbent polymers or hydrogel polymers of the invention or a composite of the invention. Preferred chemicals are especially foams, molded products, fibers, sheets, films, cables, sealing materials, liquid absorbent sanitary articles, especially diapers and sanitary napkins, vehicles for plant growth or for fungal growth regulators or for protective active ingredients, additives for building materials, packaging materials or soil additives.
[143] use of the water-absorbent polymers of the invention or the composite of the invention in chemicals, preferably in the chemicals mentioned above, especially in hygiene articles such as diapers or sanitary napkins, as well as the use of absorbent polymer particles of water as a vehicle for plant growth or regulators for the growth of fungi or active phytoprotective ingredients, is also a contribution to the solution of at least one of the problems mentioned initially. In case it is used as a vehicle for plant growth or for fungal growth regulators or for safener active ingredients, it is preferable that the plant growth active ingredients or fungal growth regulators or safeners can be released over time. of a period controlled by the vehicle.
[144] Test Methods
[145] Unless otherwise indicated hereafter, measurements performed here are in accordance with ERT methods. “ERT” refers to the EDANA Recommended Testing and “EDANA” is the European Disposables and Nonwovens Association. All test methods are in principle, unless otherwise stated, carried out at an ambient temperature of 23 ± 2 °C and a relative humidity of 50 ± 10 %.
[146] Particle Size Distribution (PSD)
[147] The particle size distribution of the water-absorbent polymer particles is determined analogously to Test Method No. WSP 220.3-10 "Particle Size Distribution" recommended by EDANA.
[148] Retention Capacity in Centrifugation (CRC)
[149] Retention capacity in centrifugation was determined by test method No. WSP 241.3-10 "Retention capacity in centrifugation" recommended by EDANA (European Association of Nonwovens and Disposables).
[150] Determination of Free Swelling Rate (FSR)
[151] The absorption rate was determined by measuring the so-called Free Swelling Rate (FSR) by the test method described in EP-A-0 443 627, on page 12.
[152] Absorption under pressure of 0.7 psi (AAP)
[153] The absorption under pressure was determined as the AAP (Absorption Under Pressure) according to the WSP test 242.3-10, on the global fraction of the particles. Consequently, 0.90 g of the test substance (sieved between 150 and 850 µm) was weighed into a test cylinder with an internal diameter of 60.0 mm, with a sieve base (400 mesh) (concentration: 0.032 g/cm2 ) and homogeneously distributed. A cylindrical weight (50 g/cm2 = 0.7 psi) with an outer diameter of 59.2 mm was placed over the test substance. Filter plates were placed in a plastic dish and covered with filter paper. The plastic plate was filled with a 0.9% NaCl solution until the liquid level reached the upper edge of the filter plates. Subsequently, the prepared test units were placed on the filter plates. After a 60 minute swelling time, the test units were removed and the weight removed. The amount of liquid absorbed was determined gravimetrically and converted to 1 gram of the test substance.
[154] Determination of permeability (saline flow conductivity - SFC)
[155] Permeability is determined by measuring the "Saline Flow Conductivity - SFC (Saline Flow Conductivity)" by the test method described in WO-A-95/26209. The initial weight of the superabsorbent material was 1.5 g instead of 0.9 g.
[156] Determination of "Fixed Height Absorption" (FHA) (0.3 psi, 20 cm)
[157] The determination is carried out by measuring the so-called "fixed height absorption" (FHA) by the test method described in EP 149 34 53 A1 on page 9 [0078] to page 10 paragraph [0087].
[158] Determination of surface tension (ST)
[159] The determination is carried out by measuring in accordance with the test method described in EP 1 493 453 A1 according to page 12 paragraphs [0105] to [0111]. A Kruss K11 tensiometer with a Wilhelmy plate was used.
[160] Determination of extractable polyether fractions
[161] The determination of extractable fractions of polyethers is based on the HPTLC method (H-III 14a dated 05/30/95) Gemeinschaftsarbeiten der DGF 152. Mitteilung [German Society of Fat Science, Collaborative Studies, 152nd Communication - German Society of Fat Sciences, Collaborative Studies, 152nd Communication]. The samples were ground, extracted with warm methanol in a Soxhlet extractor (1 hour), concentrated and then determined by thin layer chromatography on silica gel 60 TLC plates with dimensions of 20 x 20 cm . The samples were used in a standard way. The eluent used was a mixture of chloroform/methanol/water (88/11/1 percent by volume). Derivatization was performed with Dragendorff's reagent. A Camag CD60 TLC scanner with a measuring wavelength of 520 nm was used. The evaluation was performed by peak areas, which were expressed as a proportion to standard peak areas.
[162] Determination of BET surface area
[163] The BET surface area of the superabsorbents was determined using a Micromeritics Tristar 3020 Kr instrument (with krypton gas instead of nitrogen), analogous to ISO 9277 standard. The initial weight was 4.6 g, vacuumed at room temperature and a vacuum of 0.02 mbar overnight and weighed again. Vacuum was obtained using the analysis port, evacuation being carried out over a period of 6 minutes, when 10 mm of Hg was reached. Dead volume was also determined. The analysis temperature was 77.1 K. The p0 value was defined as 2.32 mm Hg (using krypton gas). Equilibrium time was measured at least 10 times (5 sec, at a rate of change of less than 0.01%).
[164] Examples
[165] The following examples serve to further illustrate the invention, but without restricting it.
[166] Table 1

[167] In the context of the present invention, the term "EO" always refers to an ethylene glycol unit. The term "PO" always refers to a propylene glycol unit and the term "BO" always refers to a butylene glycol unit.
[168] The following examples of the invention show the synergistic effect on the FSR value of the simultaneous use of polymerizable surfactants and carbonate. In this context, a defined particle size distribution (PSD) (150 µm to 710 µm) was used. The masterbatch used is a composition of 4 particle fractions before surface post-crosslinking, which have the following distribution: 15% by weight of a particle size of 150 µm to 300 µm; 50% by weight from 300 µm to 500 µm; 30% by weight from 500 μm to 600 μm and 5% by weight from 600 μm to 710 μm. PSD is established for hydrogel polymers.
[169] EP1 document 701786 B1, in paragraphs [0115 to 0117], defines the weighted average of the particle diameter as D50. According to the invention, preference is given to a range between 300 and 600 µm. Particular preference is given to a range between 350 and 550 µm and very particular preference is given to a range between 400 and 500 µm. Preference is given to a blowing agent in which more than 35% by weight of the particles have a particle size of 100 to 300 µm.
[170] The term "SX" as used in the description is understood to mean the post-thermal surface crosslinking of the precursor (PC). The precursor corresponds to the hydrogel polymer obtained after the first drying, with the distribution of particles mentioned above.
[171] In principle, the percentages for the surfactant are based on acrylic acid (unless otherwise stated, 320 g) and those for the carbonate in the mixture (usually 1000 g).
[172] Example 1
[173] surfactant No. 1, PE 8482 "allyl ether-[(EO)7-(PO)3]-H" of Table 1, was used as the additive. The amounts of surfactant used varied. The percentages of the surfactant refer to the acrylic acid and those of the carbonate for the mixture.
[174] Use without polymerizable surfactant and sodium carbonate:
[175] Example A (reference)
[176] 0.590 g polyethylene glycol-300 diacrylate (0.15% based on 81%) acrylic acid/ester content and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30% based on acrylic acid/ester content corresponding to 78 %) as crosslinking agent were dissolved in 975.762 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol % (based on acrylic acid) and a total concentration of 39.8% monomer. The monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. The polymerization was started at a temperature of 4 °C, by the successive addition of 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of distilled water. . and 0.015 g of ascorbic acid in 2 g of dest. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with circulating air for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[177] Use without polymerizable surfactant and 0.1% light sodium carbonate
[178] Example B (reference)
[179] 0.590 g polyethylene glycol-300 diacrylate (0.15% based on 81%) acrylic acid/ester content and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30% based on acrylic acid/ester content corresponding to 76%) as crosslinking agent were dissolved in 974.762 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 39.8% monomer. The monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. At a temperature of 4°C, 1 g of fine sodium carbonate (from Solvay) was added and the polymerization was started by successively adding 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of dest water. and 0.015 g of ascorbic acid in 2 g of distilled water. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with air circulation for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[180] Use of 0.3% polymerizable surfactant:
[181] Example C
[182] 0.590 g polyethylene glycol-300 diacrylate (0.15% based on 81%) acrylic acid/ester content and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30% based on acrylic acid/ester content corresponding to 76%) as crosslinking agent were dissolved in 966.162 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 40.2% monomer. Subsequently, 9.6 g of a 10% aqueous solution of comonomer number 1, PE 8482 "allyl ether-[(EO)7-(PO)3]-H" was added to this solution and the monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. The polymerization was started at a temperature of 4 °C, by the successive addition of 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of distilled water. . and 0.015 g of ascorbic acid in 2 g of dest. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with circulating air for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[183] Use of 0.1% polymerizable surfactant and 0.1% light sodium carbonate:
[184] Example D
[185] 0.590 g polyethylene glycol-300 diacrylate (0.15% based on 81%) acrylic acid/ester content and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30% based on acrylic acid/ester content corresponding to 76%) as crosslinking agent were dissolved in 971.562 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 40.0% monomer. Subsequently, 3.2 g of a 10% aqueous solution of comonomer number 1, PE 8482 "allyl ether-[(EO)7-(PO)3]-H" was added to this solution and the monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. At a temperature of 4°C, 1 g of fine sodium carbonate (from Solvay) was added and the polymerization was started by successively adding 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of dest water. and 0.015 g of ascorbic acid in 2 g of dest. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with circulating air for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[186] Use of 0.2% polymerizable surfactant and 0.1% light sodium carbonate
[187] Example E
[188] 0.590 g polyethylene glycol-300 diacrylate (0.15% based on 81%) acrylic acid/ester content and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30% based on acrylic acid/ester content corresponding to 76%) as crosslinking agent were dissolved in 968.362 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 40.1% monomer. Subsequently, 6.4 g of a 10% aqueous solution of comonomer number 1, PE 8482 "allyl ether-[(EO)7-(PO)3]-H" was added to this solution and the monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. At a temperature of 4°C, 1 g of fine sodium carbonate (from Solvay) was added and the polymerization was started by successively adding 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of dest water. and 0.015 g of ascorbic acid in 2 g of dest. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with circulating air for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[189] Use of 0.3% polymerizable surfactant and 0.1% light sodium carbonate
[190] Example F
[191] 0.590 g polyethylene glycol-300 diacrylate (0.15% based on 81%) acrylic acid/ester content and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30% based on acrylic acid/ester content corresponding to 76%) as crosslinking agent were dissolved in 965,162 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 40.2% monomer. Subsequently, 9.6 g of a 10% aqueous solution of comonomer number 1, PE 8482 "allyl ether-[(EO)7-(PO)3]-H" was added to this solution and the monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. At a temperature of 4°C, 1 g of fine sodium carbonate (from Solvay) was added and the polymerization was started by successively adding 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of dest water. and 0.015 g of ascorbic acid in 2 g of dest. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with circulating air for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[192] Post-crosslinking of the precursors ("PC") thus obtained was carried out by coating with a solution consisting of ethylene carbonate/water/aluminum lactate/aluminum sulfate in a ratio of 1/3/0.4/ 0.3% based on 100 g of superabsorbent at 170 °C for a period of 90 min in a drying cabinet.
[193] The results of examples 1A through 1F are summarized in Table 2:
[194] Table 2 PE 8482:

[195] Example 2
[196] The experimental setup corresponds to Example 1, except that the surfactant Blemmer®50PEP-300 "ester methacrylate-[(EO)3,5—(PO)2,5]-H" is used, having been previously dissolved in a portion of acrylic acid (Examples C to F). The amounts of surfactant used varied. Post-crosslinking of the precursors thus obtained was carried out by coating with a solution consisting of ethylene carbonate/water/aluminum lactate/aluminum sulfate and a ratio of 1/3/0.4/0.3 % based on 100 g of superabsorbent, at 170 °C for a period of 90 min in a drying cabinet.
[197] Use of 0.3% polymerizable surfactant:
[198] Example C
[199] 0.590 g polyethylene glycol-300 diacrylate (0.15% based on 81%) acrylic acid/ester content and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30% based on acrylic acid/ester content corresponding to 76%) as crosslinking agent were dissolved in 974,802 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 39.8% monomer. Subsequently, 0.96 g of comonomer number 2, Blemmer®50PEP-300 "ester methacrylate-[(EO)3,5—(PO)2,5]-H" pre-dissolved in acrylic acid, was added thereto. solution and the monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. The polymerization was started at a temperature of 4 °C, by the successive addition of 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of distilled water. . and 0.015 g of ascorbic acid in 2 g of dest. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with circulating air for 2 h. The dry precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[200] Use of 0.1% polymerizable surfactant and 0.1% light sodium carbonate
[201] Example D
[202] 0.590 g polyethylene glycol-300 diacrylate (0.15 % based on the acrylic acid/ester content corresponding to 81 %) and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30 % based on the acrylic acid/ester content corresponding to 76%) as crosslinking agent were dissolved in 974.442 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 39.9% monomer. Subsequently, 0.32 g of comonomer number 2, Blemmer®50PEP-300 "ester methacrylate-[(EO)3,5—(PO)2,5]-H" pre-dissolved in acrylic acid, was added thereto. solution and the monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. At a temperature of 4°C, 1 g of fine sodium carbonate (from Solvay) was added and the polymerization was started by successively adding 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of dest water. and 0.015 g of ascorbic acid in 2 g of dest. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with circulating air for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[203] Example E
[204] 0.590 g polyethylene glycol-300 diacrylate (0.15% based on 81%) acrylic acid/ester content and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30% based on acrylic acid/ester content corresponding to 76%) as cross-linking agent were dissolved in 974.122 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 39.9% monomer. Subsequently, 0.64 g of comonomer number 2, Blemmer®50PEP-300 "ester-- [(EO)3,5—(PO)2,5]-H" pre-dissolved in acrylic acid, was added to this solution. and the monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. At a temperature of 4°C, 1 g of fine sodium carbonate (from Solvay) was added and the polymerization was started by successively adding 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of dest water. and 0.015 g of ascorbic acid in 2 g of distilled water. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a drying cabinet with air circulation for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[205] Example F
[206] 0.590 g polyethylene glycol-300 diacrylate (0.15 % based on the acrylic acid/ester content corresponding to 81 %) and 1.263 g polyethylene glycol-440 monoallyl ether acrylate (0.30 % based on the acrylic acid/ester content corresponding to 76%) as cross-linking agent were dissolved in 973.802 g of an aqueous solution of sodium acrylate, with a neutralization level of 70 mol% (based on acrylic acid) and a total concentration of 39.9% monomer. Subsequently, 0.96 g of comonomer number 2, Blemmer®50PEP-300 "ester-- [(EO)3,5—(PO)2,5]-H" pre-dissolved in acrylic acid, was added to this solution. and the monomer solution was purged with nitrogen in a plastic polymerization vessel for 30 minutes to remove dissolved oxygen. At a temperature of 4°C, 1 g of fine sodium carbonate (from Solvay) was added and the polymerization was started by successively adding 0.3 g of sodium peroxodisulfate in 10 g of distilled water, 0.07 g of 35% hydrogen peroxide solution in 10 g of dest water. and 0.015 g of ascorbic acid in 2 g of distilled water. Once the final temperature (approx. 100 °C) was reached, the gel was ground with a meat grinder and dried at 150 °C in a cabinet. drying with air circulation for 2 h. The dried precursor was coarsely ground, ground and adjusted to the particle distribution described above.
[207] The results of Examples 2A through 2F are summarized in Table 3:
[208] Table 3 Blemmer®50PEP-300

[209] Example 3
[210] The experimental setup corresponds to Example 2, except that the surfactant Blemmer®55PET-800 "ester methacrylate-[(EO)10—(BO)5]-H" is used. The amounts of surfactant used varied. Post-crosslinking of the precursors thus obtained was carried out by coating with a solution consisting of ethylene carbonate/water/aluminum lactate/aluminum sulfate and a ratio of 1/3/0.4/0.3 % based on 100 g of superabsorbent, at 170 °C for a period of 90 min in a drying cabinet.
[211] The results of examples 3 are summarized in Table 4:
[212] Table 4 Blemmer®55PET-800

[213] Example 4
[214] The experimental setup corresponds to Example 2, except that the surfactant Blemmer®70PEP-350B "Ester methacrylate-[EO]5—[PO]2-H" is used. The amounts of surfactant used varied. Post-crosslinking of the precursors thus obtained was carried out by coating with a solution consisting of ethylene carbonate/water/aluminum lactate/aluminum sulfate and a ratio of 1/3/0.4/0.3 % based on 100 g of superabsorbent, at 170 °C for a period of 90 min in a drying cabinet.
[215] The results of examples 4A through F are summarized in Table 5:
[216] Table 5 Blemmer®70PEP-350B

[217] Example 5 (Comparative Example)
[218] The experimental setup corresponds to Example 1, except that the surfactant used was sodium lauryl ether sulfate (Hansa-Group AG, Duisburg). NaLES is a surfactant that cannot be incorporated by polymerization. The amounts of surfactant and carbonate used varied.
[219] Surface post-crosslinking of the precursors thus obtained was carried out by coating with a solution consisting of ethylene carbonate/water/aluminum lactate/aluminum sulfate and a ratio of 1/3/0.4/0.3 % based on 100 g of precursor and subsequent heating at 170 °C for a period of 90 min in a drying cabinet.
[220] The results of examples 5B to 5D are summarized in Table 6:
[221] Table 6 sodium lauryl ether sulfate


[222] PEG3 00DA / PEGMAE-A crosslinking: Q.2%/0.4% based on acrylic acid
[223] ** PEG300DA / PEGMAE-A crosslinking: 0.18%/0.36% based on acrylic acid
[224] In the case of a non-incorporable surfactant by polymerization, a significant deterioration of the FHA value has been found.
[225] The ST values of the water-absorbent polymers according to the examples of the invention described above are greater than 50 mN/m, preferably greater than 55 mN/m, more preferably greater than 60 mN/m, furthermore more preferably, greater than 62 mN/m. The ST value must not exceed a value of 72 mN/m. Advantageously, this minimizes the rewetting value (e.g., backsheet rewetting) in the diapers and maintains the capillarity of the superabsorbent material in the absorbent core of the diapers, which thus corresponds to high FHA values. The use of copolymerizable surface-active comonomers prevents a significant reduction in ST values.
[226] Advantageously, the simultaneous use of surfactant and carbonate comonomers leads to a synergistic increase in FSR and FHA values. According to the invention, the above-mentioned effect is found particularly in the case of water-absorbent polymers having a ST-value greater than 60. The water-absorbent polymers of the invention additionally show good parameter properties as regards to CRC, SFC and AAP values.
[227] According to the table below, it was demonstrated that, according to the invention, copolymerizable surfactants ("surfactant monomers", SM) were incorporated into the hydrogel polymer network. Extractables are reported in the last column of the table. The amount of extractable polyether fractions was analyzed based on the total amount of copolymerizable surfactants (SM) used for polymerization in %. According to the invention, less than 8% extractable surfactants/surfactant monomers have always been found. This showed that the surfactant was incorporated into the superabsorbent polymer matrix.

权利要求:
Claims (7)
[0001]
1. Process for the production of a water-absorbent polymer composition, characterized in that it comprises the process steps of (i) mixing (α1) 0.1 to 99.999% by weight of ethylenically unsaturated polymerizable monomers containing acid groups, or salts of these, or ethylenically unsaturated polymerizable monomers including a protonated or quaternized nitrogen, or mixtures thereof, with particular preference being given to mixtures including at least ethylenically unsaturated monomers containing acidic groups, (α2) 0 to 70% by weight of ethylenically unsaturated polymerizable monomers , copolymerizable with the monomers (α1), (α3) 0.001 to 10% by weight of one or more crosslinking agents, (α4) 0 to 30% by weight of water-soluble polymers, (α5) 0 to 20% by weight of one or more adjuvants, where the sum of the weights of (α1) to (α5) is 100% by weight, (ii) free radical polymerization with crosslinking to form an untreated, water-insoluble, aqueous hydrogel polymer, (iii ) drying the hydrogel polymer, (iv) grinding and sieving the water-absorbent polymer to size, (v) surface post-crosslinking the milled and sieved hydrogel polymer, and (vi) drying and finishing the water-absorbent polymer, in that the aqueous monomer solution, prior to addition of the initiator and the initiation of free radical polymerization, is mixed with 0.07 to 1% by weight of at least one surfactant from the group of non-ionic unsaturated polyether copolymers containing at least a terminal functionality, namely methyl(allyl) ether and 0.07 to 1% by weight of a blowing agent having a particle size of 10 µm to 900 µm, based on the water-absorbent polymer, wherein the agent expansion is selected from the group of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, or higher valence metal ions or mixtures thereof, wherein the unsaturated polyether surfactant is a compound of the following formula :
[0002]
2. Process for the production of a hydrogel polymer, characterized in that it comprises the steps of (i) mixing (α1) 0.1 to 99.999% by weight of ethylenically unsaturated polymerizable monomers containing acid groups, or salts thereof, or polymerizable monomers ethylenically unsaturated including a protonated or quaternized nitrogen, or mixtures thereof, with particular preference being given to mixtures including at least ethylenically unsaturated monomers containing acidic groups, (α2) 0 to 70% by weight of ethylenically unsaturated polymerizable monomers copolymerizable with the monomers (α1), (α3) 0.001 to 10% by weight of one or more crosslinking agents, (α4) 0 to 30% by weight of water-soluble polymers, (α5) 0 to 20% by weight of one or more auxiliaries , where the sum of the weights of (α1) to (α5) is 100% by weight, (ii) free radical polymerization with crosslinking to form an untreated, water-insoluble aqueous hydrogel polymer, (iii) drying of the polymer of hydrogel, (iv ) milling and sieving the water-absorbent polymer to size, wherein the aqueous monomer solution, prior to addition of initiator and initiation of free radical polymerization, is mixed with 0.07 to 1% by weight of at least one surfactant from the group of non-ionic unsaturated polyether copolymers which contain at least one terminal functionality, namely methyl(allyl) ether and 0.07 to 1% by weight of a blowing agent having a particle size of 10 µm to 900 μm, based on the hydrogel polymer, where the blowing agent is selected from the group of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, or higher valence metal ions or mixtures thereof, wherein the unsaturated polyether surfactant is a compound of the following formula:
[0003]
Process according to claim 1 or 2, characterized in that the surfactant and the blowing agent are added together in the monomer solution.
[0004]
Process according to any one of claims 1 to 3, characterized in that the blowing agents consist of sodium carbonate particles.
[0005]
Process according to any one of claims 1 to 4, characterized in that the blowing agent has a particle size of 50 µm to 500 µm e.
[0006]
Process according to any one of claims 1 to 5, characterized in that more than 35% by weight of the blowing agents have a particle size of 100 to 300 µm.
[0007]
A water-absorbent polymer characterized in that it is obtainable by a process as defined in any one of claims 1 to 6.

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法律状态:
2018-02-27| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2019-12-24| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2020-11-10| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|

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2020-12-08| B25D| Requested change of name of applicant approved|Owner name: EVONIK OPERATIONS GMBH (DE) |

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2021-04-06| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-05-18| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 29/04/2014, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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DE102013208942.2A|DE102013208942A1|2013-05-15|2013-05-15|Superabsorbent polymers with fast absorption properties and process for its preparation|

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DE102013208942.2|2013-05-15|

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PCT/EP2014/058661|WO2014183987A1|2013-05-15|2014-04-29|Superabsorbent polymers with rapid absorption properties and process for producing same|

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