JP2000063511A - Production of crosslinked polyamino acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a crosslinked polyamino acid capable of affording a biodegradable flaky water-absorbing resin composition exhibiting high water absorptivity, high rate of water absorption in particular by reaction of a polyamino acid with a specific crosslinking agent. SOLUTION: This crosslinked polyamino acid is obtained by reaction of (A) a polyamino acid with (B) a crosslinking agent, at least one kind selected from among polyepoxy compounds, polyols, polythiols, polyisocyanates, polyaziridines and polyvalent metals. Examples of this crosslinked polyamino acid include crosslinked polyaspartic acid, crosslinked polyglutamic acid, crosslinked polylysine, and respective copolymers of these polymers with other amino acids. It is preferable that this crosslinked polyamino acid is insoluble to water and/or physiological saline, and the water absorption of this crosslinked polyamino acid is 10-2,000 times its own weight for distilled water.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-absorbent resin having biodegradability, a composite comprising the same, and a method for producing the same. More specifically, the present invention relates to a water-absorbent resin having excellent water absorbency, excellent moldability, and easily decomposed at the time of disposal, a composite comprising the same, and a method for producing them.

[0002]

[Technical background of water-absorbent resin] Water-absorbent resin is a resin that can absorb several tens to several thousand times its own weight of water, and is used for sanitary items such as sanitary products, disposable diapers, breast milk pads, disposable rags, etc. Products, dressing materials for wound protection, medical underpads, medical products such as poultices, pet sheets, portable toilets, gel fragrances, gel deodorants, sweat absorbing fibers, household items such as disposable body warmers, shampoos, Gel products for set, toiletries such as moisturizers, water retention materials for agriculture and horticulture, life extension agent for cut flowers, floral foam (fixing material for cut flowers), nursery beds for seedling raising, hydroponics, vegetation sheet, seed tape, fluid Agricultural and horticultural products such as agricultural sheets for sowing and dew condensation prevention, freshness-keeping materials for food trays, food packaging materials such as drip absorbent sheets, cold storage materials, transportation materials such as water-absorbent sheets for transporting fresh vegetables, etc. Building materials for dew condensation prevention, sealing materials for civil engineering / construction, mud-blocking agents for shield construction methods, concrete admixtures, civil engineering / construction materials such as gaskets / packings, sealing materials for electronic devices such as optical fibers, and water blocking materials for communication cables. Used in a wide range of fields such as electrical equipment related materials such as inkjet recording paper, coagulants for sludge, water treatment agents such as dehydration of gasoline and oil, water removal agents, printing glue, water-swelling toys, artificial snow, etc. Has been done. Further, it is expected to be used for applications such as sustained-release fertilizers, sustained-release pesticides, sustained-release drugs, etc. by utilizing its sustained-release properties. Further, it is expected to be used as a humidity adjusting material by utilizing its hydrophilicity and as an antistatic agent by utilizing its charge retention property.

[Prior Art Concerning Water-Absorbing Resin] Examples of the water-absorbing resin used in such applications include:
Cross-linked polyacrylic acid partially neutralized product (JP-A-55-8430)
4, U.S. Pat. No. 4,625,001), a partial hydrolyzate of a starch-acrylonitrile copolymer (JP-A-46-439).
95), starch-acrylic acid graft copolymer (JP-A-51-125468), vinyl acetate-acrylic acid ester copolymer hydrolyzate (JP-A-52-14689).
No.), a copolymerized crosslinked product of 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid (European Patent No. 00681).
89), a crosslinked body of a cationic monomer (US Pat.
No. 06717), crosslinked isobutylene-maleic anhydride copolymer (US Pat. No. 4,389,513) and the like are known.

However, since these water absorbent resin compositions have no decomposability, disposal after use is a problem. Currently, these water-absorbent resins are incinerated at the time of disposal and landfilled.However, in the method of treating in an incinerator, in addition to damage to the furnace material due to heat generated during incineration, It has been pointed out that it causes global warming and acid rain. In addition, in the method of landfill processing,
Plastic has problems that it is bulky and that it does not rot so that the ground is not stable, and that there is no suitable place for landfilling.

That is, since these resins are poor in degradability and exist semi-permanently in water or soil, it is a very serious problem when considering environmental protection in waste treatment. For example, in the case of a disposable resin typified by sanitary materials such as disposable diapers and sanitary products, it costs a great deal to recycle it, and since it is incinerated in a large amount, the load on the global environment is great. When cross-linked polyacrylic acid resin is used as a water retention material for agriculture and gardening, Ca ²⁺
It has been reported to form an insoluble layer by forming a complex with polyvalent ions such as Matsumoto et al., Polymer, 42
Vol., August issue, 1993). However, it is said that such a layer itself has low toxicity, but it is completely absent in the natural world, and the effect on the ecosystem of long-term accumulation of these resins in the soil is unknown. , Needs to be thoroughly investigated and a cautious attitude is desired in its use. Similarly, in the case of nonionic resins, no complex is formed, but since it is non-degradable, it may accumulate in soil, and its effect on the natural world is doubtful.

Further, these polymerization resins use a monomer which is highly toxic to human skin and the like, and many studies have been made to remove it from the product after polymerization, It is difficult to remove it completely. It is expected to become more difficult, especially on an industrial scale. [Technical background of water-absorbent resin having biodegradability] Meanwhile, in recent years,
Biodegradable polymers have been drawing attention as "earth-friendly materials", and it has been proposed to use them as water-absorbent resins. Examples of the biodegradable water-absorbent resin used for such purposes include crosslinked polyethylene oxide (JP-A-6-157795, etc.), crosslinked polyvinyl alcohol, crosslinked carboxymethyl cellulose (US Pat. No. 4,650,716). , Crosslinked alginic acid, crosslinked starch, crosslinked polyamino acid and the like are known. Among them, polyethylene oxide cross-linked products and polyvinyl alcohol cross-linked products have a small water absorption amount, and are particularly used as materials for fresh food freshness-keeping materials, sanitary items, disposable diapers, disposable rags, paper towels, and other products that require high water absorption capacity. If not useful. Further, since these compounds can be biodegraded only by special bacteria, biodegradability is slow or does not decompose at all under general conditions. Further, when the molecular weight is increased, the degradability is extremely reduced. Further, saccharide cross-linked products such as carboxymethyl cellulose cross-linked product, alginic acid cross-linked product, starch cross-linked product, etc., contain many strong hydrogen bonds in the molecule, and thus the interaction between the molecules and the polymer is strong, so that the molecular chain is It cannot be opened widely and its water absorption capacity is not high.

[Technical background of polyamino acid-based water-absorbent resin] On the other hand, a resin obtained by crosslinking polyamino acid is biodegradable, and thus is friendly to the global environment and has an enzymatic action even when absorbed in the living body. It has been shown that it is digested and absorbed by, and does not show antigenicity in vivo, and that the decomposition products have low inflammatory properties on the skin and mucous membranes of living organisms.
It is a material that is easy on people. As a description example of such a resin, a method for irradiating poly-γ-glutamic acid with γ-rays to produce a resin having a high water absorption capacity is described (Kunioka et al., Polymer Papers, Vol. 50, No. 10, 755 pages (1
993)). However, from an industrial point of view, the 60Co irradiation equipment used for this technology requires large-scale equipment to cut off the radioactivity, and since its management requires sufficient consideration, it is not practical. Absent. Another problem is that polyglutamic acid, which is a starting material, is expensive.
Also, a method for obtaining a hydrogel by crosslinking an acidic amino acid has been reported (Akamatsu et al., US Pat. No. 3948).
863; Japanese Patent Publication No. 52-41309, Iwatsuki et al., JP-A-5-279416). Further, it has been reported that a crosslinked amino acid resin is used as a water-absorbing polymer (Sikes et al., Japanese Patent Publication No. 6-506244; U.S. Pat. Nos. 5,247,068 and 5,284,936, Suzuki et al., JP-A-7-30994).
No. 3, Harada et al., JP-A-8-59820). However, in any of the reports, these resins were not practical because they had insufficient water absorbing ability. Then, the present inventors
No. 224163 discloses a water-absorbent resin having high salt water-absorbing ability. Although this technique is extremely significant, there has been a demand for further improvement in performance of the water absorbent resin.
In particular, when used for sanitary materials and the like, there is a strong demand for a water absorbent resin having a high water absorption rate for discharged body fluid.

[0008]

DISCLOSURE OF THE INVENTION The object of the present invention is to solve the above-mentioned problems of the prior art, have biodegradability, and exhibit an excellent water absorption capacity, particularly an excellent water absorption rate. It is intended to provide a water absorbent resin composition and a composite composed of them.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a crosslinked polyamino acid having biodegradability can exhibit an excellent water absorption capacity, particularly an excellent water absorption rate. It was That is, the present invention is specified by the matters described in [1] to [12] below.

[1] A method for producing a crosslinked polyamino acid by reacting a polyamino acid with a crosslinking agent, wherein the crosslinking agent is a polyepoxy compound, a polyol, a polythiol,
A method for producing a crosslinked polyamino acid, which comprises at least one selected from the group consisting of polyisocyanate, polyaziridine, and polyvalent metal.

[2] A method for producing a crosslinked polyamino acid, which comprises reacting a polyamino acid with a crosslinking agent, wherein the crosslinking agent contains a polyepoxy compound. Manufacturing method.

[3] The method for producing a crosslinked polyamino acid according to [1] or [2], wherein the polyamino acid to be reacted with the crosslinking agent is an uncrosslinked polyamino acid.

[4] The method for producing a crosslinked polyamino acid according to [1] or [2], wherein the polyamino acid to be reacted with the crosslinking agent is a crosslinked polyamino acid.

[5] The method for producing a crosslinked polyamino acid according to any one of [1] to [4], wherein the polyamino acid is an acidic polyamino acid.

[6] The method for producing a crosslinked polyamino acid according to any one of [1] to [4], wherein the polyamino acid is polyaspartic acid.

[7] The method for producing a crosslinked polyamino acid according to any one of [1] to [4], wherein the polyamino acid is polyglutamic acid.

[8] Production of the crosslinked polyamino acid according to any one of [1] to [7], wherein the obtained crosslinked polyamino acid has an acidic amino acid residue in at least a part of the repeating unit. Method.

[9] The method for producing a crosslinked polyamino acid polymer according to [8], wherein the acidic amino acid residue is an aspartic acid residue.

[10] The crosslinked polyamino acid obtained is
Insoluble in water and / or saline,
The method for producing a crosslinked polyamino acid according to any one of [1] to [9].

[11] The water absorption of the obtained crosslinked polyamino acid with respect to distilled water is 10 to 2000 times.
The method for producing a crosslinked polyamino acid according to any one of [1] to [10].

[12] A crosslinked polyamino acid obtained by the production method described in any one of [1] to [11].

[0022]

[0023]

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. (1) Flake-shaped water-absorbent resin and composite comprising them In the present invention, the feature of the water-absorbent resin is that the crosslinked polyamino acid-based resin is made into a flaky shape instead of the conventional granular shape. A significant increase in speed is seen.
In the present invention, the flaky shape has a size of 3c on each side.
A discontinuous body having a size of m or less is called and distinguished from a continuous structure such as a film or a sheet. Examples of the flaky shape are not particularly limited, but are scale-like, mica-like, flat plate-like, flake-like,
Examples include scales. The shape of the flakes is not particularly limited, and examples thereof include a circular shape, an elliptical shape, a polygonal shape, an indefinite shape, a heart shape, and a lens shape, but other shapes may be used. Further, it may be a flat type or a three-dimensional thin piece instead of a flat plate. Further, holes or cracks may be formed as necessary, and steps or irregularities may be provided on the surface thereof. The thickness of the flakes is not particularly limited, but is preferably 0.01 μm to 1 mm, and 0.1 μm to
0.5 mm is particularly preferable. The thinner the water absorption rate, the more easily it breaks. The area of one side of the thin piece is not particularly limited, but is preferably 0.01 to 9 cm @ 2,
1-5 cm 2 is preferred. The flaky water-absorbent resin of the present invention, as compared with the granular water-absorbent resin, the reason why the water-absorption rate is high is unknown, but the present inventors consider that the granular water-absorbent resin is a trapped phenomenon or It is speculated that, as a result, the water-absorbent resin in the form of flakes is unlikely to occur while gel blocking occurs, resulting in a high water absorption rate. However, the truth of the above reasoning has nothing to do with the claimed content of the present application. The surface of the flaky water absorbent resin of the present invention may be processed. Further, the water-absorbent resin used in the present invention may be a single material or a composite material in combination with other materials. The structure of the composite is not particularly limited, for example, a method of sandwiching between pulp, nonwoven fabric, etc., a sandwich structure, a resin sheet, a method of forming a multilayer structure using a film as a support, and a resin sheet cast to form a two-layer structure. There are ways.

(2) Water absorbent resin having a flaky shape The water absorbent resin of the present invention is a crosslinked polyamino acid. The crosslinked polyamino acid is not particularly limited, but in general, crosslinked polyaspartic acid, crosslinked polyglutamic acid,
There are cross-linked polylysines and copolymers of these polymers with other amino acids. Among these, crosslinked polyaspartic acid and crosslinked polyglutamic acid having high water absorption are preferable, and crosslinked polyaspartic acid suitable for industrial production is particularly preferable. Specific examples of the amino acid component as a copolymer include, for example, 20 types of essential amino acids, L-ornithine, a series of α-amino acids, β-alanine, γ-aminobutyric acid, neutral amino acids, acidic amino acids and acidic amino acids. ω-ester, basic amino acid, N of basic amino acid
Substitutes, amino acids and amino acid derivatives such as aspartic acid-L-phenylalanine dimer (aspartame),
Examples thereof include aminosulfonic acids such as L-cysteic acid. α-amino acid is an optically active substance (L-form, D-form)
Or may be a racemate. Further, the crosslinked polyamino acid polymer may be a copolymer containing other monomer components. Examples of the monomer component of the copolymer include aminocarboxylic acid, aminosulfonic acid, aminophosphonic acid, hydroxycarboxylic acid, mercaptocarboxylic acid, mercaptosulfonic acid and mercaptophosphonic acid.
Further, polyvalent amine, polyvalent alcohol, polyvalent thiol, polyvalent carboxylic acid, polyvalent sulfonic acid, polyvalent phosphonic acid, polyvalent hydrazine compound, polyvalent carbamoyl compound, polyvalent sulfonamide compound, polyvalent phosphonamide compound. , Polyvalent epoxy compounds, polyvalent isocyanate compounds, polyvalent isothiocyanate compounds, polyvalent aziridine compounds, polyvalent carbamate compounds, polyvalent carbamic acid compounds, polyvalent oxazoline compounds, polyvalent unsaturated bond compounds, poly Examples include valent metals. When it is a copolymer, it may be a block copolymer or a random copolymer. Further, it may be a graft. Among these, a polymer having a basic skeleton of polyaspartic acid having high water absorption is preferable. In the case of the crosslinked acidic polyamino acid-based resin, the side chain structure thereof is a group having a carboxyl group in a structure in which the imide ring is simply opened, but other substituents may be introduced. For example, there are amino acid residues such as lysine, a hydrocarbon group having a carboxyl group, a sulfonic acid group, and a pendant group having a cation.

In the case of an aspartic acid residue, the carboxyl group or the side chain group may be substituted at the α-position or the β-position with respect to the amide bond of the polymer main chain. Absent. In the case of a carboxyl group, it may have a form in which hydrogen atoms are bonded or may form a salt. Examples of the counter ion of the carboxyl group include alkali metal salts, ammonium salts, amine salts and the like. The polymer used in the present invention is a cross-linked product, and in the case of an acidic polyamino acid, the polymer basic skeleton and the bonding part of the cross-linking part are amide bonds,
An ester bond and a thioester bond.

These bridging portion and side chain portion may be unsubstituted or substituted. As the substituent, an optionally branched alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an aralkyl group, an optionally substituted phenyl group, or an optionally substituted phenyl group may be substituted. Naphthyl group, optionally branched alkoxy group having 1 to 18 carbon atoms, aralkyloxy group, phenylthio group, optionally branched alkylthio group having 1 to 18 carbon atoms, branched group having 1 to 18 carbon atoms Optionally substituted alkylamino group, optionally branched dialkylamino group having 1 to 18 carbon atoms, optionally branched trialkylammonium group having 1 to 18 carbon atoms, hydroxyl group, amino group, mercapto Group, sulfonyl group, sulfonic acid group,
Examples thereof include a phosphonic acid group and salts thereof, an alkoxycarbonyl group, an alkylcarbonyloxy group and the like. The content of these crosslinked polyamino acid polymers is not particularly limited, but is preferably 10 to 100% by weight, and particularly preferably 50 to 100% by weight, based on the entire composition. The crosslinked polyamino acid used here is disclosed in JP-A-7-224163, Kobunshi Kogaku, Vol. 50, No. 10, page 755 (1993),
U.S. Pat. No. 3,948,863; JP-B-52-41309
No. 5, Unexamined Japanese Patent Publication No. 5-279416, and Japanese Patent Publication No. 6-50624.
No. 4; US Pat. Nos. 5,247,068 and 5,284,932.
No. 6, and the method described in JP-A-7-309943 can be easily manufactured. The water absorbent resin used in the present invention may be mixed with a water absorbent resin other than the crosslinked polyamino acid polymer, if necessary. If necessary, sodium chloride, colloidal silica, white carbon, ultrafine particle silica, an inorganic compound such as titanium oxide powder, or an organic compound such as a chelating agent may be added. Further, a plasticizer, an oxidizing agent, an antioxidant, a reducing agent, an ultraviolet absorber, an antibacterial agent, a bactericide, a fungicide, a fertilizer, a fragrance, a deodorant, a pigment, etc. may be mixed.

(3) Plasticizer for flaky water absorbent resin A plasticizer can be added to the flaky water absorbent resin of the present invention in some cases. As the plasticizer used in the present invention, various hydrophilic compounds can be used. The purpose is to impart flexibility to the flaky water absorbent resin. The plasticizer used in the present invention is not particularly limited, but includes water, alcohols such as methanol, ethanol, propanol, isopropanol, butanol, formic acid, acetic acid, propionic acid, valeric acid, oxalic acid, succinic acid, adipic acid, and malon. Acids, glutaric acid, fumaric acid, maleic acid, citric acid, lactic acid, malic acid, tartaric acid, carboxylic acids such as acetonedicarboxylic acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, ligninsulfonic acid and other sulfonic acids, ethylene Glycols such as glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol and polypropylene glycol, Polyvinyl alcohol, partially hydrolyzed polyvinyl alcohol, polyethylene imine,
Water-soluble synthetic polymers such as polyallylamine, amino alcohols such as ethanolamine, erythrol, erythrol, erythritol, threose, β-arabinose, xylulose, α-xylose, 2-deoxyribose, α-lyxose, ribulose, ribose, Arabitol, ribitol, α-altrose, β-altrose, β-allose, idose, α-galactose, β
-Galactose, α-quinovose, α-glucose, β
-Glucose, growth, digitarose, dichitoxose, cimarose, sorbose, tagatose, α-talose, α-fucose, psicose, β-fructose, α
-Mannose, α-rhamnose, inositol, galactitol, quercitol, glucitol, mannitol, iduronic acid, galactaric acid, α-galacturonic acid,
Glucaric acid, β-glucuronic acid, gluconic acid, guluronic acid, 2-deoxygluconic acid, mannuronic acid-6,3-
Lactone, ethyl = β-fructofuracinoid, methyl = α-galactopyranoside, methyl = β-galactopyranoside, methyl = α-glucopyracinoid, methyl = β
-Glucopyranoside, methyl = α-fructofuracinoid, methyl = α-mannopyracinoid, methyl = β-mannopyracinoid, N-acetyl-α-galactosamine, N-acetyl-α-glucosamine, N- Acetyl-
Monosaccharides such as mannosamine, α-galactosamine hydrochloride, α-glucosamine, α-mannosamine hydrochloride, muramic acid, α-heptose, β-heptose, heptulose, heptitol, octitol, octulose, neuraminic acid, nonulose, sorbitol, pentaerythritol. , Agarose, allolactol, isomaltol, xylobiose, gentiobiose, kojibiose, chondrosin, sucrose, cellobiose, sophorose,
β-turanose, α, α-trehalose, nigerose,
Hyalobiuronic acid, β-maltose, α-mellibiose, α-lactose, laminaribiose, disaccharides such as rutinose, β-gentianose, stachyose, cellotriose, planteose, maltotriose, α-melezitose, lacto-N-tetraose, Trisaccharides such as raffinose, agarose, amylose, amylopectin, araban, arabinogalactan, alginic acid, inulin, curdlan, galactan, xylan, chitin, glucomannan, chondroitin, chondroitin-4-
Sulfate, chondroitin-6-sulfate, dextrin,
Dextran, hyaluronic acid, pullulan, pekunanoic acid,
Mannan, lichenan, levan, chitosan, chitosan-succinic acid modified product, starch, cationized starch, cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, acetyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose,
Polysaccharides such as cellulose nitrate, cellulose acetate, cationized cellulose, 20 kinds of essential amino acids, L-ornithine, a series of α-amino acids, β-alanine, γ-aminobutyric acid, neutral amino acids, acidic amino acids, and ω of acidic amino acids. −
Amino acids and amino acid derivatives such as ester, basic amino acid, N-substituted form of basic amino acid, aspartic acid-L-phenylalanine dimer (aspartame), L-
Aminosulfonic acid such as cysteic acid, adenine, adenosine, adenosine-3'-phosphate, inosine, uracil, uridine, orotic acid, xanthine, xanthosine,
Nucleic acids and their derivatives such as guanine, guanosine, cytidine, cytosine, dihydrouracil, thymidine, deoxyadenosine, deoxyuridine, deoxyguanosine, deoxycytidine, hypoxanthine, pseudouridine, phosphatidic acid, phosphatidylglycerin, phosphatidylethanolcholine, phosphatidylethanolamine, phosphatidylethanolamine , Phosphatidylserine, bisphosphatidic acid, phospholipids such as sphingomyelin, ascorbic acid, inositol, choline, thiamine hydrochloride, nicotinic acid, nicotinamide, pantothenic acid, pyridoxine hydrochloride, pyridoxal hydrochloride, pyridoxamine dihydrochloride, cyanocobalamin, Glutathione, coenzyme A, coenzyme B12, thiamine pyrophosphate, pyridine nucleotide, pyriamine Kisarurin acid, pyridoxamine phosphate, flavin mononucleotide, include vitamins and coenzymes such as folate coenzymes. Among these, compounds having abundant hydrophilic groups in the molecule are preferable because they are easily mixed uniformly. That is, sorbitol, pentaerythritol, iduronic acid, galactaric acid, α-galacturonic acid, glucaric acid, β-glucuronic acid, gluconic acid, guluronic acid, 2-deoxygluconic acid, mannuronic acid-
6,3-lactone, α-galactosamine hydrochloride, α-mannosamine hydrochloride, muramic acid, alginic acid, chondroitin-4-sulfate, chondroitin-6-sulfate, hyaluronic acid, pekunanoic acid, chitosan, chitosan-succinic acid modified , Cationized starch, carboxymethyl cellulose, hydroxyethyl cellulose, cationized cellulose are preferable, sorbitol, pentaerythritol, gluconic acid, α-galactosamine hydrochloride, chondroitin-4-sulfate, chondroitin-6-sulfate, alginic acid, hyaluronic acid. , Chitosan, modified chitosan-succinic acid, cationized starch, carboxymethyl cellulose and cationized cellulose are particularly preferable. The plasticizer used in the present invention may be used as a mixture with two or more kinds of other plasticizers, if necessary. The amount of these plasticizers used is not particularly limited, but is preferably 0.1 to 70% by weight, more preferably 0.1 to 30% by weight, based on the composition.

(4) Method for producing flaky cross-linked polyamino acid polymer The method for producing the flaky cross-linked polyamino acid polymer is not particularly limited. Examples of the production method include (4-1) a method of shearing and then casting a gel of a crosslinked polyamino acid-based water-absorbent resin swollen with water or a polar organic solvent / water, (4-2)
There is a method of hydrolyzing a flaky crosslinked polysuccinimide, and (4-3) a method of reacting a non-crosslinked polyamino acid and a crosslinking agent after or while casting.
The flakes of the present invention are obtained by fragmentation.Fragmentation for discontinuing the resin is a method of fragmenting in the manufacturing process, and a film or sheet-shaped composition is obtained and crushed. A method of fragmenting may be used. The method of fragmenting in the manufacturing process is not particularly limited, for example, by utilizing the shrinkage and swelling of the resin during the drying process, cracking the resin, fragmentation method, swelling due to rapid temperature changes. ,
There is a method of shrinking and cracking the resin to fragment it, or a method of applying physical force to fragment. Even after the manufacturing process, fragmentation can be performed using the above principle. The obtained flakes can be further shredded or crushed within a range that does not impair the physical properties. The obtained thin piece of water absorbent resin may be subjected to sizing, classification, sieving and the like depending on the case. In addition, the obtained flaky water-absorbent resin may be subjected to surface treatment such as surface cross-linking according to circumstances.

(4-1) After shearing the gel of the crosslinked polyamino acid water absorbent resin swollen with water or a polar organic solvent / water,
As one of the methods for producing the flaky water absorbent resin of the present invention, the method of casting is to shear the gel of the water absorbent resin swollen with water or water and a polar organic solvent, and cast the suspension. , There is a way to dry. Alternatively, there is a method in which the water-absorbent resin is sheared while being wet-milled with water or water and a polar organic solvent, the suspension is cast, and dried. The solvent used is water or a mixture of water and a polar organic solvent. The water-miscible organic solvent is not particularly limited, but a water-miscible organic solvent is preferable. For example, methanol, ethanol, propanol,
Alcohols such as isopropanol, butanol, 2-methoxyethanol and 2-ethoxyethanol, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and dipropylene glycol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, Cyclic ethers such as tetrahydrofuran and dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, N
-Methylpyrrolidone, N, N'-dimethylimidazolidinone, dimethyl sulfoxide, sulfolane and the like. In particular, it is easy to dry, and in that the solvent does not remain in the composition after drying, methanol, ethanol, propanol,
Isopropanol and butanol are preferred. The amount and ratio of the organic solvent and water used are not particularly limited, but the ratio of the organic solvent is preferably 0.1 to 90% by weight, and 10 to 60.
Weight percent is particularly preferred. Since the water-absorbent resin swells with water alone, the viscosity of the suspension becomes extremely high, which makes casting difficult. Therefore, it is difficult to use it at a high concentration, and it can be used only at a low concentration. The method of using water alone is suitable for a method of producing a resin having a thin film thickness. When water and a water-miscible organic solvent are used, the swelling degree of the water-absorbent resin can be controlled by adjusting the ratio of the organic solvent and water, so that the viscosity and concentration of the suspension before casting can be adjusted. in this way,
We can manufacture thin to thick film. The water absorption amount, which is one of the water absorption capabilities of the water absorbent resin used in the present invention,
It depends on the intended use. The amount of water absorption is not particularly limited, but in the case of distilled water, it is preferably 10 to 2000 times the unit weight of the water absorbent resin, and 10
0 to 1000 times is more preferable. The percentage of water used is
The amount of the resin-containing composition is preferably 5 to 99.9% by weight, and particularly preferably 20 to 80% by weight. When manufacturing a thin water-absorbent resin with a thin film thickness, it is better to use a relatively low-concentration water-absorbent resin suspension, and the amount of organic solvent / water used is twice the weight of the water-absorbent resin. Is preferred, especially 1-5
It is preferably 100 times by weight. In the case of producing a water absorbent resin in the form of flakes having a relatively large film thickness, it is better to use a high concentration water absorbent resin suspension, and the amount of organic solvent / water used is 1 to 1 of the water absorbent resin. It is preferably 100 times by weight, and particularly preferably 1 to 50 times by weight. The film thickness of the flaky water absorbent resin varies depending on the intended use. When the film thickness is thin, the water absorption rate is high, but in the same area, the weight is small and the water absorption is low. When the film thickness is thick, the water absorption rate decreases, but the water absorption amount per unit area increases. The shearing is usually performed by a shearing machine or a homogenizer. These devices are not particularly limited as long as the suspension containing the gel can be sheared. For example, the stirring blade rotates at high speed (for example, 500 to 20000 ppm), and the bladed stirring blade rotates at high speed. Rotation (for example, 500 to 20000p
pm) is preferably used. More specifically, examples thereof include a mixer with a blade, a pipeline mixer, a homomix line mixer, a disintegrator, a spike mill, and a golator pump. The base material used for casting is not particularly limited, but generally includes a glass plate, a plastic plate, a metal plate, paper and the like. When releasability is required, a glass plate, a Teflon plate, a metal plate or the like is preferable. The drying temperature of the cast water-absorbent resin suspension is not particularly limited, but is 20 to 15
0 degreeC is preferable and 40-100 degreeC is especially preferable. Here, the drying temperature may be a method of gradually raising the temperature, or the cast product may be put in a rapidly high temperature. However, when the temperature is gradually raised, a substance close to a continuous body is obtained, and when it is rapidly dried, fragmentation proceeds. Further, when cast at a high concentration, a continuous body is likely to be formed and a resin in the form of a film or sheet may be obtained, but it may be used by cutting it into a required size at the time of casting or drying.

(4-2) Method for hydrolyzing flaky crosslinked polysuccinimide The flaky crosslinked polysuccinimide used in the present invention is produced by the following method. That is, it can be obtained by adding a cross-linking agent to a solution of polysuccinimide, rapidly and uniformly stirring, casting on a glass plate or the like, and removing the solvent. Alternatively, it can be obtained by reacting a polysuccinimide film or sheet with a crosslinking agent. The obtained flaky crosslinked polysuccinimide is hydrolyzed in dilute alkaline water to open the imide ring and dried to obtain a water absorbent resin having a flaky shape. The solvent used for producing the flaky cross-linked polysuccinimide may be any solvent that can dissolve the polysuccinimide, for example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N, N '
-Dimethyl imidazolidinone, dimethyl sulfoxide,
Examples thereof include sulfolane. Among them, N, N-dimethylformamide and N, N-dimethylacetamide, which have high solubility of polysuccinimide and are easily removed by drying, are particularly preferable. The concentration of the polysuccinimide at the time of producing the flaky cross-linked polysuccinimide is not particularly limited, but is preferably 0.1 to 50% by weight, and particularly preferably 1 to 40% by weight. The crosslinking agent used is not particularly limited as long as it is a polyfunctional compound that reacts with the imide ring,
Examples include polyamines and polythiols. Generally, hydrazine, ethylenediamine, propylenediamine, 1,4-
Butanediamine, heptamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tetradecamethylenediamine, hexadecamethylenediamine, 1-amino- Aliphatic polyamines such as 2,2-bis (aminomethyl) butane, tetraaminomethane, diethylenetriamine and triethylenetetramine, norbornenediamine, 1,4-diaminocyclohexane, 1,3,5-triaminocyclohexane and isophoronediamine. Aromatic polyamines such as alicyclic polyamines, phenylenediamines, tolylenediamines, and xylylenediamines, basic amino acids represented by lysine, ornithine, or the like. Polyamines such as esters, monoamine compounds such as cystamine bonded by a disulfide bond and derivatives thereof, 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,6-hexane Dithiols, Aliphatic polythiols such as pentaerythrithiol, Alicyclic polyols such as cyclohexanedithiol, Aromatic polythiols such as xylylenedithiol, Benzenedithiol, Toluenedithiol, Trimethylolpropane tris (thioglycolate), Trimethylolpropane tris Examples thereof include esters such as (3-mercaptopropionate) pentaerythritol tetrakis (thioglycolate) and pentaerythritol tetrakis (3-mercaptopropionate) polythiol. Of these, preferred are hydrazine, which has low odor and has high reactivity with the imide ring of polysuccinimide, ethylenediamine, propylenediamine, 1,4-butanediamine, heptamethylenediamine, hexamethylenediamine, lysine, and ornithine. . The amount of the cross-linking agent used depends on the functional number and molecular weight of the cross-linking agent. Although the amount used is not particularly limited, it is 0.5 to 0.5 with respect to the polysuccinimide.
30 mol% is preferable, and 1 to 20 mol% is particularly preferable. The drying conditions after casting the polysuccinimide solution containing the crosslinking agent are not particularly limited. Although the drying temperature varies depending on the solvent used, it is generally 20 to 150.
C is preferable, and 40 to 100 C is more preferable. Here, the drying temperature may be a method of gradually raising the temperature, or the cast product may be put in a rapidly high temperature. However, when the temperature is gradually raised, a substance close to a continuous body is obtained, and when it is rapidly dried, fragmentation proceeds. The method for cross-linking the flaky cross-linked polysuccinimide used in the present invention may be either a uniform method as a whole or surface cross-linking. As a method of uniformly crosslinking the whole, a crosslinking agent may be uniformly mixed with a solution of polysuccinimide, cast, and dried. In the case of surface cross-linking, first, a solution of polysuccinimide is cast without adding a cross-linking agent and dried, or a small amount of a cross-linking agent is added and cast and dried to form a flaky cross-linked polysuccinimide. To get Surface cross-linking is performed by spraying a solution containing a cross-linking agent or immersing the obtained flaky material in the solution containing the cross-linking agent.

The method of hydrolysis is not particularly limited, but, for example, the flaky cross-linked polysuccinimide is immersed in alkaline water for hydrolysis. In some cases, it may be carried out with stirring. Reagents used for the hydrolysis of flaky cross-linked polysuccinimide are not particularly limited, sodium hydroxide, potassium hydroxide, alkali metal hydroxides such as lithium hydroxide, sodium carbonate, potassium carbonate,
Alkali metal carbonates such as lithium carbonate, alkali metal hydrogen carbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate,
Examples thereof include alkali metal acetates such as sodium acetate and potassium acetate, alkali metal salts such as sodium oxalate, and ammonia water. Of these, inexpensive sodium hydroxide and potassium hydroxide are preferable. Further, depending on the case, a method other than the hydrolysis reaction may be used. For example,
This is a method of reacting an amine, thiol, etc. containing a glycino group, a carboxyl group, a sulfonic acid group, a cationic group and the like. The concentration of alkaline water used is 0.01-8% by weight
Is preferred, and 0.1 to 5% by weight is more preferred.

Water or water and a polar organic solvent are used as the solvent for the hydrolysis reaction. With water alone, the resin swells as the hydrolysis proceeds, so a polar organic solvent is mixed in some cases to control the degree of swelling of the gel. The polar organic solvent used is not particularly limited, for example, alcohols such as methanol, ethanol, propanol, isopropanol, butanol, 2-methoxyethanol, 2-ethoxyethanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, di- Glycols such as propylene glycol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, cyclic ethers such as tetrahydrofuran and dioxane, N, N-dimethylformamide,
There are N, N-dimethylacetamide, N-methylpyrrolidone, N, N'-dimethylimidazolidinone, dimethyl sulfoxide, sulfolane and the like. In particular, methanol, ethanol, propanol, isopropanol and butanol are preferable because they are easy to dry and no solvent remains in the composition after drying. The reaction temperature during hydrolysis is
It may be selected depending on the alkali concentration in the solution. That is, when the alkali concentration is high, low temperature may be selected, and when the alkali concentration is low, the temperature may be increased. However, at high concentration and high temperature, the flakes themselves are decomposed, so mild conditions are preferable. The temperature is preferably 5 to 100 ° C, more preferably 10 to 40 ° C. The time for the alkali ring opening varies depending on the concentration of the alkaline water, but it is generally 30
Seconds to 100 hours are preferable, and 5 minutes to 10 hours are particularly preferable. The flaky material after the alkali ring-opening may be
The acid or acid salt may be replaced with another type of salt. Counterions used for salt exchange include alkali metal salts, ammonium salts, amine salts and the like. Specifically, sodium, potassium, alkali metal salts such as lithium, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, ethyltrimethylammonium, trimethylpropylammonium, butyltrimethylammonium, Pentyltrimethylammonium,
Hexyl trimethyl ammonium, cyclohexyl trimethyl ammonium, benzyl trimethyl ammonium, triethyl propyl ammonium, triethyl butyl ammonium, triethyl pentyl ammonium,
Ammonium salts such as triethylhexylammonium, cyclohexyltriethylammonium, benzyltriethylammonium, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triethanolamine, tripropanolamine, tributanolamine, tripentanol Amine, trihexanolamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine, dibenzylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, methylhexylamine , Methylamine, ethylamine, propylamine, butylamine, pentyl Min, hexylamine, octylamine, decylamine, dodecylamine, there are amine salts of hexadecylamine etc., or the like. In this, when the molecular weight of the counter ion becomes large, the molecular weight per unit becomes relatively large, so the water absorption amount per unit weight becomes small.
The smaller the molecular weight of the counterion, the better. In addition, since it may come into contact with human skin or the like depending on the application, it is preferable that the skin or mucous membranes of living organisms have low inflammatory properties, and inorganic salts or ammonium salts are preferable. Among them, especially sodium,
Potassium and triethanolamine are preferred. The flaky material after the alkali ring-opening can be used by neutralizing the acid in some cases. The degree of neutralization is preferably 50 to 100%, particularly preferably 70 to 100%. Although the method is not particularly limited, for example, the film or sheet after the alkali ring-opening may be dipped in a pH-adjusted solution for a necessary time. The time is not particularly limited, but is generally 30.
Seconds to 100 hours are preferable, and 5 minutes to 10 hours are particularly preferable. The method for drying the flaky material after the alkali ring-opening is not particularly limited, but it can be carried out under normal pressure or under reduced pressure. The drying temperature is not particularly limited, but is generally 20.
-150 degreeC is preferable and 40-100 degreeC is especially preferable.

(4-3) Method of reacting non-cross-linked polyamino acid with a cross-linking agent after casting or while casting, the flaky cross-linked polyamino acid of the present invention is used in a solution of polyamino acid containing an acidic group such as carboxylic acid. It can be obtained by adding a cross-linking agent, stirring uniformly, casting on a glass plate or the like, reacting while neutralizing the solvent, and neutralizing. Alternatively, it can be obtained by reacting a polyaspartic acid film or sheet with a crosslinking agent to neutralize it. The cross-linking agent used is not particularly limited as long as it reacts with the carboxyl group contained in the acidic polyamino acid or a functional group other than the carboxyl group. Examples thereof include polyols, polythiols, polyamines, polyepoxy compounds, polyisocyanates, polyaziridine compounds, polyvalent metals and the like. Examples of the cross-linking agent are ethylene glycol, propylene glycol, butylene glycol, propylene glycol, 1,3-propanediol, butanediol, pentanediol, hexanediol, heptanediol, hexanediol, hexanediol, heptanediol, octanediol. , Nonanediol, decanediol, undecanediol, dodecanediol,
Hexadecanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, hexaethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, hexapropylene glycol, polypropylene glycol, glycerin, di Glycerin, EO-modified glycerin, CL-modified glycerin, trimethylolethane, trimethylolethane, tributyrolethane, trihexanolethane, trimethylolpropane, triethylolpropane, tripropanolpropane, tributyrolpropane, trihexanolpropane, EO-modified Trimethylolpropane, CL modified trimethylolprop Bread, ethanolamine, diethanolamine, triethanolamine, dipentaerythritol, EO-modified pentaerythritol, CL-modified pentaerythritol, sorbitol, EO-modified sorbitol, xylylenediol, bis (hydroxyethyl) benzene, bis (hydroxypropyl) benzene, bis (Hydroxybutyl) benzene, tris (hydroxymethyl) benzene, tris (hydroxyethyl) benzene, cyclohexanediol, polyols such as bis (hydroxymethyl) cyclohexane, catechol, hydroquinone, resorcinol, pyrogallol, dihydroxyfuran, dihydroxypyridine, etc. Phenols, ethylenediamine, propylenediamine, 1,3-
Diaminopropane, butylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, hexadecamethylenediamine, bis (2-aminoethyl) ) Ether, bis (3-
Aminopropyl) ether, bis (4-aminobutyl)
Ether, bis (5-aminopentyl) ether, bis (6-aminohexyl) ether, bis (12-aminododecyl) ether, 1,2-bis (2′-aminoethoxy) ethane, 1,2-bis ( 3'-aminopropoxy) ethane, 1,2-bis (4'-aminobutoxy) ethane, 1,3-bis (2'-aminoethoxy) propane, 1,3-bis (3'-aminopropoxy) propane, Bis (aminoethyloxyethyl) ether, bis (aminopropyloxypropyl) ether, bis (aminobutyloxybutyl) ether, xylylenediamine, bis (aminoethyl) benzene, bis (aminopropyl) benzene, bis (aminobutyl) Benzene, tris (aminomethyl) benzene, tris (aminoethyl)
Benzene, cyclohexanediamine, bis (aminomethyl) cyclohexane, isophoronediamine, bis-2,
Polyamines such as 2- (4′-aminocyclohexyl) propane, norbornenediamine, diethylenetriaminetriethylenetetramine, tetraethylenepentamine, polyethylenepolyamine, lysine, ornithine, cystine, cysteamine, diketopiperazine of lysine, diketopiperazine of ornithine , Tolylenediamine, phenylenediamine, aminobenzylamine, bis-2,2-
Aromatic polyamines such as (4′-aminophenyl) propane, epichlorohydrin, epibromhydrin, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, pentaethylene glycol Diglycidyl ether, hexaethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether, EO-modified trimethylolpropane triglycidyl ether, CL-modified trimethylolpropane triglycidyl ether, Ditrimethylolpropane diglycidyl ether, ditrimethylolpropane triglycidyl ether, EO-modified ditrimethylolpropane triglycidyl ether, CL-modified ditrimethylolpropane triglycidyl ether, pentaerythritol diglycidyl ether, pentaerythritol triglycidyl ether, pentaerythritol tetraglycidyl ether, EO modified pentaerythritol tetraglycidyl ether, CL modified pentaerythritol tetraglycidyl ether, dipentaerythritol diglycidyl ether, dipentaerythritol triglycidyl ether, dipentaerythritol tetraglycidyl ether, EO modified dipentaerythritol tetraglycidyl ether, CL modified dipenta Erythrito Rutetraglycidyl ether, sorbitol polyglycidyl ether, N, N-diglycidylaniline, N, N-diglycidyltoluidine, bis-2,2- (4'-glycidyloxycyclohexyl) propane, phthalic acid diglycidyl ether, tetrahydrophthalic acid Diglycidyl ether,
Hexahydrophthalic acid diglycidyl ether, diglycidyl p-oxybenzoic acid, resorcinol diglycidyl ether, bisphenol A diglycidyl ether,
Bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, vinylcyclohexene dioxide, alicyclic diepoxy acetal,
Polyepoxy compounds such as alicyclic diepoxy adipate, alicyclic diepoxy carboxylate, ethylene diisocyanate, propylene diisocyanate, 1,3-diisocyanatopropane, butylene diisocyanate, pentamethylene diisocyanate Nato, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, undecamethylene diisocyanate, dodecamethylene diisocyanate, hexadecamethylene diisocyanate , Bis (2-isocyanatoethyl) ether, bis (3-isocyanatopropyl) ether, bis (4-isocyanatobutyl) ether, bis (5-isocyanatopentyl) Ether, bis (6-isocyanatohexyl) ether, bis (12-isocyanatododecyl) ether, 1,2-bis (2'-isocyanatoethoxy) ethane, 1,2-bis (3'-isocyanatopropoxy) ) Ethane, 1,2-bis (4'-isocyanatobutoxy) ethane, 1,3-bis (2'-isocyanatoethoxy) propane, 1,3-bis (3'-isocyanatopropoxy) propane, bis ( Isocyanatoethyloxyethyl) ether, bis (isocyanatopropyloxypropyl) ether, bis (isocyanatobutyloxybutyl) ether, xylylene diisocyanate, bis (isocyanatoethyl) benzene, bis (isocyanatopropyl) benzene, bis (Isocyanatobutyl) benzene, tris (isocyanatomethyl) benzene Benzene, tris (isocyanatoethyl) benzene, cyclohexane diisocyanate, bis (isocyanatomethyl)
Cyclohexane, isophorone diisocyanate, norbornene diisocyanate, polyisocyanates such as bis-2,2- (4'-isocyanatocyclohexyl) propane, magnesium, calcium, strontium,
Barium, titanium, vanadyl, chromium, manganese, iron,
Cobalt, nickel, copper, zinc, aluminum, zirconium, molybdenum, ruthenium, rhodium, palladium, cadmium, tin, tungsten, platinum, gold, mercury,
Examples include polyvalent metal ions such as samarium and europium. Alternatively, self-crosslinking using ultraviolet rays, radiation or the like may be used without using a crosslinking agent. Of these, polyepoxy compounds are preferable in consideration of reactivity. Also,
Considering biodegradability or safety after degradation, glycerin derivatives, ethylene glycol derivatives, polyethylene glycol derivatives, sorbitol derivatives, lysine, ornithine, cysteamine, and cystine are preferable. The method for crosslinking the film or sheet of the crosslinked polysuccinimide used in the present invention may be a uniform method as a whole or surface crosslinking. As a uniform crosslinking method, the crosslinking agent may be uniformly mixed with an aqueous solution of polyaspartic acid. In the case of surface cross-linking, a solution of polysuccinimide is dried without a cross-linking agent, and the obtained film or sheet is sprayed with a solution containing a cross-linking agent, or
It may be dipped in a solution containing a cross-linking agent.

[0035]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples. In the following Examples and Comparative Examples, "part" means "part by weight". The measurement of the amount of water absorption was performed by using the tea bag method for distilled water. That is, a water absorbent resin is put in a tea bag, the tea bag is immersed in excess distilled water for 1 hour, the tea bag is pulled up and drained for 1 minute,
The weight was measured. The amount of water absorption was determined by subtracting the weight of the resin before swelling and the weight of the blank from the weight of the tea bag containing the swollen resin, with the weight of the tea bag soaked in water for 1 hour containing no water-absorbing resin as the blank. The value obtained by dividing the above value by the weight of the resin was taken as the water absorption amount (g / g resin). Further, the water absorption rate was evaluated by measuring the time for gelating a predetermined amount of artificial urine. That is, 150 g (30 times amount) of artificial urine was poured into a beaker containing 5 g of a water-absorbent resin, gelled without stirring, and the time when the fluidity of the gel disappeared was measured. The composition of artificial urine is urea 1.94%, sodium chloride 0.8%, calcium chloride 840 ppm, magnesium sulfate 2050 pp.
m aqueous solution was used.

Example 1 Under a nitrogen stream, 5 parts of polysuccinimide having a weight average molecular weight of 96,000 was dissolved in 30 parts of DMF, and 1.8 parts of lysine methyl ester dihydrochloride and 3.1 parts of triethylamine were dissolved. A part was inserted, and after stirring at room temperature for 5 hours, stirring was stopped and the reaction was carried out for 30 hours. 100 parts of methanol was added to the reaction product, and the mixture was stirred at room temperature for 2 hours and reprecipitated.
The precipitate was collected by suction filtration and washed with methanol followed by water. The obtained precipitate was suspended in 1000 parts of distilled water,
A weight% sodium hydroxide aqueous solution was added dropwise so that the pH was in the range of 10 to 11, and an aqueous 8% caustic soda solution was continuously added until the pH of the reaction solution did not decrease. pH
After the pH does not drop, dilute hydrochloric acid is added to adjust the pH of the reaction solution to 7
Added until. The resulting mixture was discharged into 3000 parts of acetone, dried and pulverized to obtain 7.6 parts of a water-absorbent polymer. 7 parts of this water absorbent resin, 50 parts of methanol,
Suspend in 50 parts of distilled water and use a mixer with a blade for 8
After shearing at 000 rpm, the suspension was cast on a Teflon plate to a thickness of 30 μm, placed in a drier at 100 ° C. and dried for 6 hours to obtain a flaky water-absorbent resin. The water absorption of this resin was 290 times as large as that of 1 g of the resin piece, and the water absorption rate was very high at 1 minute 45 seconds.

[Example 2] 7 parts of the water-absorbent resin obtained in Example 1 and 0.7 part of sorbitol were suspended in 50 parts of methanol and 50 parts of distilled water and treated in the same manner as in Example 1 to obtain flakes. A water absorbent resin in the form of a solid was obtained. The water absorption amount of this resin was 260 times as large as that of 1 g of the resin piece, and the water absorption rate was very high at 1 minute 31 seconds.

Example 3 A flaky water absorbent resin was obtained in the same manner as in Example 1 except that fine particles of chitosan were used instead of sorbitol. The water absorption of this resin is 250 times as large as 1 g of resin piece,
The water absorption rate was extremely fast at 1 minute 33 seconds.

Example 4 1 part of the water absorbent resin obtained in Example 1 was suspended in 100 parts of distilled water and treated in the same manner as in Example 1 to obtain a flaky water absorbent resin. The water absorption of this resin was 300 times as large as that of 1 g of the resin piece, and the water absorption rate was very high at 1 minute 39 seconds.

Example 5 2 parts of the flaky composition obtained in Example 1 was sandwiched between 3 cm × 3 cm polylactic acid nonwoven fabric coated with starch paste and dried at 60 ° C. for 2 hours to obtain a sheet. . When 60 parts of artificial urine was added to this complex and the water absorption rate was measured, it was as fast as 1 minute and 46 seconds.

Example 6 An aqueous solution prepared by dissolving 25 parts of polysuccinimide having a weight average molecular weight of 68,000 in 75 parts of DMF and adding 1.5 parts of hexamethylenediamine in 3 parts of distilled water was added for 5 minutes. After vigorous stirring, the obtained slurry was cast on a glass plate and dried under a nitrogen stream at 120 ° C. for 10 hours. 10 parts of the obtained flaky water-absorbent resin was added to 50 parts of distilled water and 50 parts of methanol, and 51.5 parts of an 8% caustic soda aqueous solution was added thereto while adjusting the pH to 11 or less while gently stirring. After reacting for further 10 hours, the obtained gel was washed with 100 parts of distilled water, dried at 60 ° C. for 10 hours, and further crushed to give a flaky water absorbent resin 1.
1.5 parts were obtained. The water absorption of this resin was 250 times as large as that of 1 g of the resin piece, and the water absorption rate was very high at 1 minute 22 seconds.

[Example 7] 25 parts of polyaspartic acid having a weight average molecular weight of 104,000 and 1.9 parts of ethylene glycol diglycidyl ether were dissolved in 100 parts of distilled water and cast on a glass plate to give 120 It was dried at ℃ for 5 hours, and further reacted at 200 ℃ for 30 minutes. A 2% caustic soda aqueous solution was added to the obtained flaky resin to adjust the pH to 7. The gel obtained was washed with 100 parts of distilled water,
Flake-shaped water absorbent resin 7.8 after drying at 0 ° C for 10 hours
was gotten. When the water absorption of this resin was measured, it was 1 g
It is as large as 190g against the resin piece of, and the water absorption rate is 5 minutes
It was as fast as 2 seconds.

Comparative Example 1 The water absorption amount and water absorption rate of the water absorbent resin obtained in Example 1 were measured. The water absorption of this resin was as large as 470 g per 1 g of the resin piece, but the water absorption rate was as slow as 5 minutes and 45 seconds.

[Comparative Example 2] The water absorption amount and water absorption rate of the crosslinked polyacrylic acid resin were measured. Water absorption of this resin is 1g
It is as big as 570 g for the resin piece of, and the water absorption rate is 2 minutes 5
It was relatively fast, but there was no biodegradability.

Comparative Example 3 The water absorption amount and water absorption rate of the biodegradable crosslinked carboxymethyl cellulose resin were measured. The water absorption of this resin is 170g for 1g of resin piece.
The water absorption rate was 2 hours and 30 minutes, which was very low.

[0046]

EFFECTS OF THE INVENTION According to the present invention, as a water absorbent used for disposable diapers, agricultural and horticultural purposes, etc., it has biodegradability and has excellent water absorption capacity, especially a high water absorption rate, and high water absorption. A resin was obtained. According to the present invention, it is possible to provide a water-absorbent resin which has biodegradability and exhibits an excellent water-absorbing ability, and particularly an excellent water-absorption rate, and a composite comprising the same.

Claims (12)

[Claims] 1. A method for producing a crosslinked polyamino acid, which comprises reacting a polyamino acid with a crosslinking agent, wherein the crosslinking agent comprises a polyepoxy compound, a polyol, a polythiol, a polyisocyanate, a polyaziridine, and a polyvalent metal. A method for producing a crosslinked polyamino acid, which comprises at least one selected from the group. 2. A method for producing a crosslinked polyamino acid, which comprises reacting a polyamino acid with a cross-linking agent, wherein the cross-linking agent contains a polyepoxy compound. Production method. 3. The method for producing a crosslinked polyamino acid according to claim 1, wherein the polyamino acid to be reacted with the crosslinking agent is an uncrosslinked polyamino acid. 4. The method for producing a crosslinked polyamino acid according to claim 1, wherein the polyamino acid to be reacted with the crosslinking agent is a crosslinked polyamino acid. 5. The method for producing a crosslinked polyamino acid according to claim 1, wherein the polyamino acid is an acidic polyamino acid. 6. The method for producing a crosslinked polyamino acid according to claim 1, wherein the polyamino acid is polyaspartic acid. 7. The method for producing a crosslinked polyamino acid according to claim 1, wherein the polyamino acid is polyglutamic acid. 8. The method for producing a crosslinked polyamino acid according to claim 1, wherein the obtained crosslinked polyamino acid has an acidic amino acid residue in at least a part of the repeating unit. 9. The method for producing a crosslinked polyamino acid polymer according to claim 8, wherein the acidic amino acid residue is an aspartic acid residue. 10. The method for producing a crosslinked polyamino acid according to claim 1, wherein the obtained crosslinked polyamino acid is insoluble in water and / or physiological saline. 11. The method for producing a crosslinked polyamino acid according to claim 1, wherein the water absorption of the obtained crosslinked polyamino acid with respect to distilled water is 10 to 2000 times. 12. A crosslinked polyamino acid obtained by the method according to any one of claims 1 to 11.