JPH10287754A - Film and sheet and their production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film or sheet which can be converted into biodegradable film or sheet excellent in water absorbency by compounding a crosslinked polysuccinimide with a plasticizer. SOLUTION: The crosslinked polysuccinimide may be a copolymer contg. units derived from other monomers (e.g. an aminocarboxylic acid), too. Though not specifically limited, this compsn. may further contain other additives. Pref., the sheet is prepd. by using another water-absorbent resin (e.g. a resin having the backbone formed from polyaspartic acid), if necessary. The amt. of the plasticizer compounded is pref. 0.01-70 wt.%, though not specifically limited. An example of the plasticizer is sorbitol. A crosslinker needed for producing a crosslinked polycarboximide is e.g. a polyamine. The solvent used in the production is e.g. N,N-dimethylformamide. The polysuccinimide used pref. has a wt. average mol.wt. of 30,000 or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to films and sheets having excellent water absorbability and decomposability, excellent moldability, and useful as intermediates of a water absorbent, and methods for producing them.

[0002]

[Prior art]

[Prior art relating to water-absorbent resin] A water-absorbent resin is a resin that can absorb water tens to thousands times its own weight. Sanitary goods such as sanitary products, disposable diapers, breast milk pads, disposable rags, and dressings for wound protection. Materials, medical supplies such as medical underpads, cataplasms, pet seats, portable toilets, gel air fresheners, gel deodorants, sweat-absorbing fibers, disposable warmers and other daily necessities, shampoos, set gels,
Toiletries such as moisturizers, water retention materials for agriculture and horticulture, life-promoting agents for cut flowers, floral foam (fixed material for cut flowers), nursery beds for nursery, hydroponic cultivation, vegetation sheets, seed tapes, fluid sowing, dew condensation prevention Agricultural and horticultural products such as agricultural sheets, freshness preserving materials for food trays, food packaging materials such as drip-absorbent sheets, cold insulators, transport materials such as water absorbing sheets for transporting fresh vegetables, building materials for preventing condensation, Civil engineering / building materials such as sealing materials for civil engineering / building, anti-sludge agent for shield method, concrete admixture, gasket / packing, etc.
Sealing materials for electronic devices such as optical fibers, waterproof materials for communication cables, materials related to electric devices such as ink jet recording paper, coagulants for sludge, gasoline, dehydration of oils, water treatment agents such as water removing agents, printing It is used in a wide range of fields, such as glue, water-swellable toys, and artificial snow. In addition, it is expected to be used for sustained-release fertilizers, sustained-release pesticides, sustained-release drugs, and the like by utilizing the sustained-release properties of the chemicals. Further, it is also expected to be used as a humidity control material utilizing its hydrophilicity, and as an antistatic agent utilizing its charge retention.

Examples of the water-absorbing resin used for such applications include, for example, a partially neutralized cross-linked polyacrylic acid (JP-A-55-84304, US Pat. No. 4,625,001).
No.), partially hydrolyzed starch-acrylonitrile copolymer (JP-A-46-43995), starch-acrylic acid graft copolymer (JP-A-51-125468), vinyl acetate-acrylate copolymer Combined hydrolyzate (JP-A-52-14689), 2-acrylamide-2-
Copolymerized cross-linked product of methylpropanesulfonic acid and acrylic acid (European Patent 0068189), cross-linked product of cationic monomer (US Pat. No. 4,906,717), cross-linked isobutylene-maleic anhydride copolymer (US Pat. No. 4,389,513)
No.) are known.

However, since these water-absorbent resin compositions do not have degradability, disposal after use is a problem. At present, these water-absorbent resins are incinerated and landfilled at the time of disposal. It has been pointed out that it causes global warming and acid rain. In addition, in the method of landfill, plastic has a problem that the volume is bulky and the ground is not stable because it does not rot. In addition, there is no longer a place suitable for landfill.

That is, these resins are poorly decomposable and exist semipermanently in water and soil, which is a very serious problem in view of environmental conservation in waste treatment. For example, in the case of disposable resins represented by sanitary materials such as disposable diapers and sanitary articles, recycling the resin requires a great deal of cost, and the amount of incineration is large, so that the burden on the global environment is great. When a crosslinked polyacrylic acid resin is used as a water retention material for agriculture and horticulture, Ca ²⁺
It is reported that the complex forms a complex with polyvalent ions such as those described above to form an insoluble layer (Matsumoto et al., Polymer, 42
Vol., August issue, 1993). However, although such layers are said to have low toxicity per se, they are completely absent in nature, and the effects on ecosystems of long-term accumulation of these resins in soil are unknown. , Need to be thoroughly examined and its use requires a careful attitude. Similarly, in the case of a nonionic resin, a complex is not formed, but the nondecomposable resin may accumulate in soil due to its nondegradability, and its effect on the natural world is doubtful.

Further, these polymerization resins use monomers which are highly toxic to human skin and the like, and many studies have been made to remove them from products after polymerization. Is difficult to remove. In particular, it is expected to be more difficult in production on an industrial scale.

[Technical background of water-absorbing resin having biodegradability] On the other hand, in recent years, biodegradable polymers have attracted attention as “earth-friendly materials”, and it has been proposed to use this as a water-absorbing resin. ing. Examples of the biodegradable water-absorbing resin used for such applications include, for example, a polyethylene oxide crosslinked product (JP-A-6-15779).
No. 5, etc.), cross-linked polyvinyl alcohol, cross-linked carboxymethyl cellulose (US Pat. No. 4,650,716),
Alginic acid crosslinked products, starch crosslinked products, polyamino acid crosslinked products, and the like are known. Among these, crosslinked polyethylene oxide and crosslinked polyvinyl alcohol have low water absorption, and are particularly used as materials for products requiring high water absorption such as freshness preserving material for fresh food, sanitary products, disposable diapers, disposable rags, and paper towels. If not useful.

[0008] Further, since these compounds can be biodegraded only by special bacteria, biodegradability is slow or not decomposed under general conditions. When the molecular weight is further increased, the decomposability extremely decreases. In addition, crosslinked saccharides such as crosslinked carboxymethylcellulose, crosslinked alginic acid, and crosslinked starch have many strong hydrogen bonds in their molecules, and therefore have strong interactions between molecules and between polymers. It cannot be opened widely and its water absorption capacity is not high.

[Technical Background of Polyamino Acid Diameter-Based Water Absorbent Resin] On the other hand, a resin obtained by crosslinking a polyamino acid is biodegradable and thus is friendly to the global environment. It has been shown that it is digested and absorbed by the body, and does not show antigenicity in vivo, and that the degradation 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 of producing a resin having high water absorbing ability by irradiating poly-γ-glutamic acid with γ-rays is described (Kunioka et al., Collection of Polymers, Vol. 50, No. 10, 755 pages (1
993)). However, from the industrial point of view, ⁶⁰ Co irradiation equipment used in this technique, in order to shut off radioactivity requires large-scale facilities, realistic due to the need for sufficient consideration to the management is not. Another problem is that polyglutamic acid as 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. 3,948,394).
No. 863; JP-B-52-41309; Iwazuki 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., JP-A-6-506244; US 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 case, in order to use it as a water absorbent such as a disposable diaper,
Its water absorbing ability was not enough.

[Technical Background on Shape of Water Absorbent Resin]
Regardless of biodegradability or non-biodegradability, these resins are mostly granular and poor in moldability, so they have high water absorption, especially for fresh food fresheners, sanitary products, disposable diapers, disposable rags, paper towels, etc. At present, when used as a material for products requiring high performance, it is sandwiched between pulp and the like and used in a multilayer structure. However, advanced technology is required to distribute the granular resin evenly between the pulp. On the other hand, a method of kneading fine powders of these resins with a thermoplastic resin (Japanese Patent Application Laid-Open Nos.
No. 7-19046) and a method of mixing and dispersing in a thermosetting composition (JP-A-59-8753, JP-A-58-157).
No. 847, JP-A-7-82401, etc.) are also known. However, in these compositions, since the water-absorbing resin is dispersed in the binder resin or the like, it is difficult to completely express the water-absorbing ability of the water-absorbing resin. It did not show as much water absorption. As described above, there is no sheet or film having substantially excellent water absorbing ability, and it has been strongly desired. On the other hand, no highly water-absorbable sheets and films having biodegradability have been found, and water-absorbent sheets and films having degradability and high water-absorbing ability have been strongly desired.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a biodegradable, useful film and sheet as an intermediate of an excellent water-absorbing material, and a film and sheet thereof. It is to provide a manufacturing method of.

[0012]

Means for Solving the Problems The present inventors have diligently studied to solve the above-mentioned problems and have completed the present invention. That is, the present invention is specified by the matters described in the following [1] to [9].

[1] Films and sheets containing cross-linked polysuccinimide.

[2] Films and sheets containing a crosslinked polysuccinimide and a plasticizer.

[3] An uncrosslinked polysuccinimide and a crosslinking agent are simultaneously cast and reacted.
[1] The method for producing a film and sheet according to [2].

[4] After casting the uncrosslinked polysuccinimide, a crosslinking agent is reacted.
[1] The method for producing a film or sheet according to [2].

[5] The method for producing a film or sheet according to [1] or [2], wherein a suspension of the crosslinked polysuccinimide and an organic solvent and / or water is cast.

[6] The method for producing a film or sheet according to [1] or [2], wherein a gel comprising a crosslinked polysuccinimide and an organic solvent and / or water is sheared and cast.

[7] The crosslinking agent is a polyamine.
The method for producing a film or sheet according to any one of [3] to [6].

[8] The method for producing a film or sheet according to any one of [3] to [6], wherein a plasticizer is added in the step of producing a film and sheet containing the crosslinked polysuccinimide. Method.

[9] A film and sheet produced by the production method according to any one of [3] to [8].

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

(1) Films and Sheets and Composites Composed Thereof Although the sheets and films used in the present invention are not strictly distinguished, those thinner than 0.2 mm are generally called films, Is called a sheet. In the present invention,
Hereinafter, films and sheets are abbreviated as sheets for convenience. Generally, films and sheets have a smooth and uniform thickness, but may have an uneven structure such as an embossed shape. The surface of the film and sheet of the present invention may be processed, and holes may be formed as necessary. On the other hand, the sheets used in the present invention are mainly used after being converted into a water-absorbing sheet, but can also be used as a structural material by utilizing the heat resistance and the like. It may be used alone or in a composite with other materials.

(2) Sheets Made of Crosslinked Polysuccinimide The sheets of the present invention are made of a crosslinked polysuccinimide polymer which is an anhydride of crosslinked polyaspartic acid. The basic skeleton of the crosslinked polysuccinimide has succinimide in which two water molecules are dehydrated and condensed from aspartic acid as a repeating unit, but may contain other amino acids in addition to aspartic acid. Specific examples of the amino acid component include, for example, 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, ω-esters of acidic amino acids, bases Amino acids and N-substituted basic amino acids, 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 acids are optically active forms (L-form, D-form)
Or a racemic form.

The crosslinked polysuccinimide may be a copolymer containing another monomer component. Examples of the monomer component of the copolymer include aminocarboxylic acid, aminosulfonic acid, aminophosphonic acid, hydroxycarboxylic acid, mercaptocarboxylic acid, mercaptosulfonic acid, and mercaptophosphonic acid. In addition, polyamines, polyhydric alcohols, polythiols, polycarboxylic acids, polysulfonic acids, polyphosphonic acids, polyhydrazine compounds, polycarbamoyl compounds, polysulfonamide compounds, polyphosphonamide compounds , Polyvalent epoxy compounds, polyvalent isocyanate compounds, polyvalent isothiocyanate compounds, polyvalent aziridine compounds, polyvalent carbamate compounds, polyvalent carbamic acid compounds, polyvalent oxazoline compounds, polyvalent reactive unsaturated bond compounds, Valent metals and the like. When it is a copolymer, it may be a block copolymer or a random copolymer. Also, it may be a graft. The composition of the crosslinked polysuccinimide in the sheets is not particularly limited, but may be a resin alone or may include other additives. When other additives are added, the amount of addition is not particularly limited, but is preferably 0.01 to 70% by weight based on the whole composition, and 0.1 to 70% by weight.
50% by weight is particularly preferred.

The sheets used in the present invention may be mixed with a water-absorbing resin other than the crosslinked polysuccinimide, if necessary. If necessary, an inorganic compound such as salt, colloidal silica, white carbon, ultrafine silica, 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 and the like may be mixed. Here, when guiding the sheets as a water absorbing body,
It is preferable to use a resin having polyaspartic acid having a high water absorbency as a basic skeleton. When used as a water-absorbing material, it leads to a crosslinked polyaspartic acid-based resin.
At this time, the main chain structure is changed from aspartic acid to one water molecule.
One of them has polyaspartic acid dehydrated and condensed as a repeating unit. The side chain structure is a group having a carboxyl group simply by opening the imide ring, but other substituents may be introduced. For example, there are an amino acid residue such as lysine, a hydrocarbon group having a carboxyl group, a sulfonic acid group, and a pendant group having a cation.

The carboxyl group or side chain group is
In the case of an aspartic acid residue with respect to the amide bond of the polymer main chain, it may be substituted at the α-position or at the β-position. In the case of a carboxyl group, a form in which a hydrogen atom is bonded or a salt may be constituted. Examples of the counter ion of the carboxyl group include alkali metal salts, ammonium salts, and amine salts. The polysuccinimide used in the present invention is a crosslinked product, and the bonding portion between the polymer basic skeleton and the crosslinked portion is an amide bond, an ester bond, or a thioester bond.

These cross-linking portions and side chain portions 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 Naphthyl group, C1-C18 optionally branched alkoxy group, aralkyloxy group, phenylthio group, C1-C18 optionally branched alkylthio group, C1-C18 branched atom An alkylamino group which may be substituted, an optionally branched dialkylamino group having 1 to 18 carbon atoms, an optionally branched trialkylammonium group having 1 to 18 carbon atoms, a hydroxyl group, an amino group, a mercapto group 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.

(3) Plasticizer of Sheets The sheets of the present invention may optionally contain a plasticizer. As the plasticizer of the present invention, a hydrophobic compound can be used when it is used as a sheet of crosslinked polysuccinimide, and various hydrophilic compounds can be used when it is derived and used as a water absorbent sheet. The purpose is sheets,
The purpose is to impart flexibility to the water-absorbent sheet. In some cases, there is no need to particularly add. The plasticizer used in the present invention is not particularly limited, but includes water, alcohols such as methanol, ethanol, propanol, isopropanol and butanol, formic acid, acetic acid, propionic acid,
Valeric acid, oxalic acid, succinic acid, adipic acid, malonic acid,
Glutaric acid, fumaric acid, maleic acid, citric acid, lactic acid,
Carboxylic acids such as malic acid, tartaric acid and acetone dicarboxylic acid, sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid and ligninsulfonic acid, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene Glycols such as glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, and polypropylene glycol, water-soluble synthetic polymers such as polyvinyl alcohol, partially hydrolyzed polyvinyl alcohol, polyethyleneimine, and polyallylamine; amino alcohols such as ethanolamine; Troll, erythrrol, 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-quinobose, α-glucose, β-glucose, growth, digitalose, dichitoxose, simarose,
Sorbose, tagatose, α-talose, α-fucose, psicose, β-fructose, α-mannose,
α-rhamnose, inositol, galactitol, queritol, glucitol, mannitol, iduronic acid, galactic acid, α-galacturonic acid, glucaric acid,
β-glucuronic acid, gluconic acid, guluronic acid, 2-deoxygluconic acid, mannuronic acid-6,3-lactone, ethyl = β-fructofurasinoid, methyl = α-galactopyranoside, methyl = β-galactopira Noside, methyl = α-glucopyranosinoid, methyl = β-glucopyranoside, methyl = α-fructoflacinoid, methyl =
α-mannopyrassinoid, methyl = β-mannopyrassinoid, N-acetyl-α-galactosamine, N-acetyl-α-glucosamine, N-acetyl-mannosamine,
α-galactosamine hydrochloride, α-glucosamine, α-mannosamine hydrochloride, muramic acid, α-heptose, β-
Monosaccharides such as heptose, heptulose, heptitol, octitol, octulose, neuraminic acid, nonurose, sorbitol, pentaerythritol, allolactol, isomaltol, xylobiose, gentiobiose, kojibiose, chondrosin, sucrose, cellobiose, α-, β-α- -Disaccharides such as trehalose, nigerose, hyalobiuronic acid, β-maltose, α-melibiose, α-lactose, laminaribiose, rutinose, β-gentianose, stachyose, cellotriose, planteose,
Maltotriose, α-merezitose, 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-modified succinic acid, starch,
Polysaccharides such as cationized starch, cellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, acetylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, cellulose nitrate, cellulose acetate, cationized cellulose, 20 kinds of essential amino acids, L-ornithine, a series of α -Amino acid, β
-Alanine, γ-aminobutyric acid, neutral amino acids, acidic amino acids, ω-esters of acidic amino acids, basic amino acids,
N-substituted basic amino acids, amino acids and amino acid derivatives such as aspartic acid-L-phenylalanine dimer (aspartame), aminosulfonic acids such as L-cysteic acid, adenine, adenosine, adenosine-3'-phosphate, inosine , Uracil, uridine, orotic acid, xanthine, xanthosine, guanine, guanosine, cytidine, cytosine, dihydrouracil, thymidine, deoxyadenosine, deoxyuridine, deoxyguanosine,
Deoxycytidine, hypoxanthine, nucleic acids such as pseudouridine and derivatives thereof, phosphatidic acid, phosphatidylglycerin, phosphatidylinositol, phosphatidylethanolamine, phosphatidylcholine,
Phospholipids such as phosphatidylserine, bisphosphatidic acid, sphingomyelin, ascorbic acid, inositol, choline, thiamine hydrochloride, nicotinic acid, nicotinamide, pantothenic acid, pyridoxine hydrochloride, pyridoxal hydrochloride, pyridoxamine dihydrochloride, cyanocobalamin, glutathione , Coenzyme A, coenzyme B ₁₂ , thiamine pyrophosphate, pyridine nucleotide, pyridoxal phosphate, pyridoxamine phosphate, flavin mononucleotide, vitamins such as folate coenzyme, and coenzymes.

Among these, compounds having abundant hydrophilic groups in the molecule are easily mixed uniformly, and the resulting film,
This is preferable because the sheet does not become turbid. That is, sorbitol, pentaerythritol, iduronic acid, galactic 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, modified chitosan-succinic acid, cationized starch,
Carboxymethylcellulose, hydroxyethylcellulose, and cationized cellulose are preferable, and sorbitol, pentaerythritol, gluconic acid, α-galactosamine hydrochloride, chondroitin-4-sulfate, chondroitin-6-sulfate, alginic acid, hyaluronic acid, chitosan, chitosan-succinate Acid-modified, cationized starch, carboxymethylcellulose and cationized cellulose are particularly preferred. If necessary, the plasticizer used in the present invention may be used as a mixture with two or more other plasticizers.
The amount of these plasticizers is not particularly limited, but when used, is preferably 0.01 to 70% by weight, more preferably 0.1 to 30% by weight, based on the composition.

The timing and method of adding the plasticizer are not particularly limited, and may be either during the production of a film or a sheet comprising the production of a non-crosslinked polysuccinimide.

(4) Method for Producing Cross-Linked Polysuccinimide The method for producing cross-linked polysuccinimide is not particularly limited, but (4-1) a method in which a non-cross-linked polysuccinimide and a cross-linking agent are simultaneously cast and reacted, -2) a method of casting a non-crosslinked polysuccinimide and then reacting a crosslinking agent; (4-3) a method of casting a suspension of a crosslinked polysuccinimide and an organic solvent and / or water;
4) There is a method in which a gel composed of crosslinked polysuccinimide and an organic solvent and / or water is sheared and cast. In these production methods, the crosslinking agent used is not particularly limited as long as it is a polyfunctional compound that reacts with the imide ring, even if the production order is different. Examples include polyamines, polythiols, and the like. For example, hydrazine, ethylenediamine, propylenediamine, 1,4-butanediamine,
Heptamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tetradecamethylenediamine, hexadecamethylenediamine, 1-
Aliphatic polyamines such as amino-2,2-bis (aminomethyl) butane, tetraaminomethane, diethylenetriamine and triethylenetetramine, norbornenediamine, 1,4-diaminocyclohexane, 1,3,5-triaminocyclohexane, isophoronediamine Alicyclic polyamines such as phenylenediamine, tolylenediamine, aromatic polyamines such as xylylenediamine, lysine, basic amino acids represented by lysine or esters thereof, and monoamino compounds such as cystamine by disulfide bonds; Polyamines such as those bonded and derivatives thereof, 1,2-ethanedithiol, 1,
3-propanedithiol, 1,4-butanedithiol,
Aliphatic polythiols such as 1,6-hexanedithiol and pentaerythrithiol, alicyclic polyols such as cyclohexanedithiol, aromatic polythiols such as xylylenedithiol, benzenedithiol and toluenedithiol, trimethylolpropane tris (thioglycolate) And esters such as trimethylolpropane tris (3-mercaptopropionate) pentaerythritol tetrakis (thioglycolate) and pentaerythritol tetrakis (3-mercaptopropionate) polythiol. Among them, odorazine having low odor and high reactivity with an imide ring of polysuccinimide, ethylenediamine, propylenediamine, 1,4-butanediamine, heptamethylenediamine, hexamethylenediamine, lysine, ornithine are preferable. preferable.

The amount of the crosslinking agent used depends on the functional number of the crosslinking agent,
It depends on the molecular weight and the required physical properties according to the intended use. That is, if strength is required for the structure, the amount of crosslinking agent may be increased to increase the degree of crosslinking, and if high water absorption is required, the amount of crosslinking agent may be reduced and the degree of crosslinking may be reduced. . However, when the degree of cross-linking is low, it is easy to break during hydrolysis, so it is necessary to adjust the concentration of alkali or the like for hydrolysis. The amount of use is not particularly limited,
It is preferably from 0.5 to 30 mol%, more preferably from 1 to 20 mol%, based on polysuccinimide. The substrate used for casting is not particularly limited, but generally includes a glass plate, a plastic plate, a metal plate, paper and the like. When mold releasability is required, a glass plate, a Teflon plate or the like is preferable. Hereinafter, these production methods will be described.

(4-1) Method of Casting and Reacting Non-Crosslinked Polysuccinimide and Crosslinking Agent Simultaneously The method for producing a film comprising a crosslinked polysuccinimide of the present invention uses an uncrosslinked polysuccinimide in an organic solvent. And / or dissolving or dispersing in water, adding a crosslinking agent, casting, and reacting the polysuccinimide with the crosslinking agent. As an example, a film is obtained by adding a cross-linking agent to a solution of polysuccinimide, stirring the mixture quickly and uniformly, casting on a glass plate or the like, reacting the cross-linking agent, and removing the solvent if necessary.

The solvent used is not particularly limited as long as it can dissolve polysuccinimide. For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N, N'-dimethylimidazolidinone , Dimethyl sulfoxide, sulfolane and the like. Among these, N, N-dimethylformamide, which has high solubility of polysuccinimide and is easily removed by drying,
N, N-dimethylacetamide is particularly preferred. In some cases, a poor solvent which does not dissolve the polysuccinimide may be added. The concentration of the polysuccinimide at the time of producing the crosslinked polysuccinimide film is not particularly limited, but is preferably 0.1 to 50% by weight, and particularly preferably 5 to 40% by weight. The molecular weight of the polysuccinimide used is not particularly limited. When a polysuccinimide having a low molecular weight is used, it is necessary to increase the degree of crosslinking. It is preferable to use polysuccinimide having a large molecular weight as a structural material. As for the molecular weight, the weight average molecular weight is preferably 30,000 or more, more preferably 50,000 or more.

The drying conditions after casting the polysuccinimide solution containing the crosslinking agent are not particularly limited. It may be carried out at normal pressure or under reduced pressure. The drying temperature varies depending on the solvent used, but is generally 20 to 150 ° C.
Is preferable, and particularly preferably 40 to 100 ° C. In some cases, the crosslinked polysuccinimide film of the invention is
The surface may be further crosslinked. When performing surface cross-linking, it can be produced by reacting a cross-linking agent with the surface of the cross-linked polysuccinimide film. That is, surface cross-linking can be performed by spraying a solution containing a cross-linking agent on the obtained cross-linked polysuccinimide film or immersing the film in a solution containing a cross-linking agent.

(4-2) Method of Casting Non-Crosslinked Polysuccinimide and Reacting with Crosslinking Agent The method for producing a film comprising a crosslinked polysuccinimide of the present invention comprises the steps of: / Or dissolved or dispersed in water, cast,
In this method, a cross-linking agent is further brought into contact with the surface to react the polysuccinimide with the cross-linking agent.

The solvent used is not particularly limited as long as it can dissolve the polysuccinimide.
N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N, N′-dimethylimidazolidinone, dimethylsulfoxide, sulfolane and the like. Among these, N, N-dimethylformamide and N, N-dimethylacetamide, which have high solubility of polysuccinimide and are easily removed by drying, are particularly preferable.
In some cases, a poor solvent which does not dissolve the polysuccinimide may be added. The concentration of the polysuccinimide at the time of producing the non-crosslinked polysuccinimide film is not particularly limited, but is preferably 0.1 to 50% by weight, and more preferably 5 to 5% by weight.
0% by weight is preferred. The molecular weight of the polysuccinimide to be used needs to be high enough to give a film-forming property. Preferably, it is 50,000 or more, more preferably 10
More than ten thousand. The non-crosslinked polysuccinimide is dried after casting, but the drying method is not particularly limited. It may be carried out at normal pressure or under reduced pressure. The drying temperature is
Although it depends on the evaporability of the solvent used, it is generally preferably from 20 to 150 ° C, particularly preferably from 40 to 100 ° C. Depending on the purpose of use, the drying of the crosslinked polysuccinimide may be carried out completely so that no solvent remains, or may be such that the solvent remains. When the cross-linking agent is reacted in a state where almost no solvent remains, only the surface of the film reacts, and when the cross-linking agent is reacted in a state where the solvent remains, cross-linking proceeds not only on the surface but also inside. The state of crosslinking is
You can choose according to the purpose of use.

(4-3) Method of Casting a Suspension of Crosslinked Polysuccinimide and Organic Solvent and / or Water The method for producing a film comprising the crosslinked polysuccinimide of the present invention comprises the steps of: And / or a method of casting a suspension of water to remove the solvent. The suspension should be in the form of crosslinked polysuccinimide as small as possible, using a crosslinked polysuccinimide wet-milled or dry-milled, or a method of casting after wet-milling with a solvent used before casting. Effective and preferred.

The wet pulverization is usually performed by a shearing machine or a homogenizer. These devices are not particularly limited as long as they can crush the suspension containing particles,
For example, the stirring blade rotates at high speed (for example, 500 to 2000).
0 ppm), and those in which the stirring blade with blades rotates at high speed (for example, 500 to 20,000 ppm) are preferably used. More specifically, a mixer with a blade,
Pipeline mixer, homomix line mixer,
Disintegrators, spike mills, Golator pumps and the like can be mentioned. Although the solvent to be used is not particularly limited, for example, water, N, N-dimethylformamide,
Alcohols such as N, N-dimethylacetamide, N-methylpyrrolidone, N, N′-dimethylimidazolidinone, dimethylsulfoxide, sulfolane, methanol, ethanol, propanol, 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, dimethylsulfoxide, sulfolane and the like. Particularly, methanol, ethanol, propanol, isopropanol, and butanol are preferred because drying is easy and no solvent remains in the composition after drying.

Here, it is effective to add an organic solvent having a high affinity for the crosslinked polysuccinimide for the purpose of binding the particles. For example, N, N-dimethylformamide,
There are N, N-dimethylacetamide, N-methylpyrrolidone, N, N′-dimethylimidazolidinone, dimethylsulfoxide, and sulfolane, and N, N-dimethylformamide is preferred. The concentration of the crosslinked polysuccinimide is not particularly limited, but is preferably higher before casting, preferably 1 to 50% by weight, and particularly preferably 5 to 50% by weight. As a pretreatment, the solvent may be concentrated and the concentration may be higher than the above concentration.

After the casting, drying is performed to remove the solvent if necessary. The drying method is not particularly limited.
It may be carried out at normal pressure or under reduced pressure. The drying temperature depends on the solvent used, but is generally 2
The temperature is preferably from 0 to 150 ° C, particularly preferably from 40 to 100 ° C.

(4-4) Method of Casting by Shearing Gel Made of Cross-Linked Polysuccinimide and Organic Solvent and / or Water The method for producing a film made of cross-linked polysuccinimide of the present invention comprises: This is a method of shearing a gel composed of a solvent and / or water, removing the solvent after casting. The difference between this method and the method described in (4-3) is that (4-3) uses a powder of cross-linked polysuccinimide, whereas this method uses an organic solvent of cross-linked polysuccinimide. Consists in using a swollen gel. That is, the isolated cross-linked polysuccinimide may be used after being swollen with an organic solvent, or a gel obtained by reacting the polysuccinimide and the cross-linking agent in the organic solvent may be used.

The stirrer used is not particularly limited, but a stirrer capable of high rotation is preferable. The shearing is usually performed by a shearing machine or a homogenizer. These devices are not particularly limited as long as they can shear the suspension containing the gel. For example, the stirring blade is rotated at high speed (for example, 50 rpm).
(0 to 20,000 ppm), and those in which the stirring blade with blades rotates at high speed (for example, 500 to 20,000 ppm) are preferably used. More specifically, bladed mixers, pipeline mixers, homomix line mixers, disintegrators, spike mills,
Golator pump and the like. As a solvent to be used, an organic solvent having a high affinity for the crosslinked polysuccinimide is used. For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N, N'-dimethylimidazolidinone, dimethylsulfoxide, sulfolane and the like can be mentioned. Among these, N, N-dimethylformamide and N, N-dimethylacetamide, which have a high affinity for crosslinked polysuccinimide and are easily removed by drying, are particularly preferred. The concentration of the crosslinked polysuccinimide is not particularly limited, but is preferably higher before casting, more preferably 1 to 50% by weight, and particularly preferably 5 to 5% by weight.
0% by weight is preferred. As a pretreatment, the solvent may be concentrated and the concentration may be higher than the above concentration. After the casting, if necessary, drying is performed to remove the solvent. The drying method is not particularly limited. It may be carried out at normal pressure or under reduced pressure. The drying temperature varies depending on the solvent used, but is generally 20 to 150 ° C.
Is preferable, and particularly preferably 40 to 100 ° C.

[0045]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The main uses of the crosslinked polysuccinimide sheets of the present invention are water-absorbing sheets. Was evaluated. The present invention is not limited only to the embodiments. In the following Examples and Comparative Examples, “parts” means “parts by weight”. The measurement of the water absorption was performed on distilled water. That is, the water-absorbent sheet was immersed in excess distilled water for 10 hours, and the swollen gel was removed for 15 hours.
Water was drained on a 0-mesh wire sieve for 10 minutes, the weight of the swollen gel was measured, and the value obtained by dividing the value obtained by subtracting the weight of the water-absorbent sheet before swelling by the weight of the water-absorbent sheet was used as the water absorption ( g / g resin).

[Production Example of Cross-Linked Polysuccinimide Film] [Example 1] Under a nitrogen stream, 5 parts of a polysuccinimide having a weight average molecular weight of 96,000 was dissolved in 30 parts of DMF, and lysine methyl ester. 1.8 parts of dihydrochloride and 3.1 parts of triethylamine are inserted, and the mixture is stirred at a high speed for 10 minutes at room temperature.
It was cast to a thickness of 0.3 mm on a glass plate and reacted for 30 hours under a nitrogen stream. After the reaction, the mixture was transferred to a reduced-pressure drier and the solvent was removed at 120 ° C. and 20 mmHg to obtain a crosslinked polysuccinimide film.

Example 2 25 parts of a polysuccinimide having a weight average molecular weight of 96,000 was dissolved in 75 parts of DMF, and the solution was dissolved at 5 ° C.
And 1.5 parts of hexamethylenediamine in 3 parts of distilled water.
The aqueous solution dissolved in the mixture was added, and the mixture was vigorously stirred for 5 minutes.
The obtained slurry was cast on a glass plate so as to have a thickness of 0.3 mm, and was heated at 60 ° C. for 3 hours at room temperature under a nitrogen stream.
After drying for 5 hours at 120 ° C. for 10 hours, a film of crosslinked polysuccinimide was obtained.

Example 3 A crosslinked polysuccinimide film was obtained in the same manner as in Example 2 except that 0.5 part of sorbitol was added to and dissolved in the DMF solution of polysuccinimide. .

Example 4 10 parts of polysuccinimide having a weight average molecular weight of 186,000 was dissolved in 30 parts of DMF, and the obtained solution was cast on a glass plate so as to have a thickness of 0.3 mm. Dry at 10 ° C. for 10 hours. The selected film was immersed in an aqueous solution of 5 parts of hexamethylenediamine dissolved in 3 parts of distilled water for 5 minutes and dried at 100 ° C. for 2 hours to obtain a crosslinked polysuccinimide film.

Example 5 An aqueous solution obtained by dissolving 25 parts of polysuccinimide having a molecular weight of 96,000 in 75 parts of DMF and 1.5 parts of hexamethylenediamine in 7 parts of distilled water was added. The reaction was allowed to stand for a period of time. The obtained gel was shredded at 8000 rpm for 1 minute with a mixer equipped with a blade together with 200 parts of methanol. The precipitate was collected by filtration and dried at 60 ° C. for 1 hour. Using 20 parts of the obtained crosslinked polysuccinimide, ethanol 80
, 80 parts in a mixer with a blade together with 20 parts of DMF.
The wet pulverization was performed at 00 rpm for 30 minutes. The obtained slurry was cast on a glass plate so as to have a thickness of 0.5 mm, and under a nitrogen stream, at room temperature for 3 hours, at 60 ° C. for 5 hours,
After drying at 120 ° C. for 10 hours, a sheet of crosslinked polysuccinimide was obtained.

Example 6 An aqueous solution obtained by dissolving 25 parts of polysuccinimide having a molecular weight of 96,000 in 75 parts of DMF and 1.5 parts of hexamethylenediamine in 7 parts of distilled water was added. The reaction was allowed to stand for a period of time. The obtained gel was sheared together with 50 parts of DMF in a mixer equipped with a blade at 8000 rpm for 10 minutes. The obtained slurry was cast so as to have a thickness of 0.5 mm.
After drying for 10 hours, a sheet of crosslinked polysuccinimide was obtained.

[Production Example of Film Made of Crosslinked Polyaspartic Resin] [Example 7] The film of the crosslinked polysuccinimide obtained in Example 1 was immersed in a 1% aqueous solution of caustic soda,
It was left for 0 hours. The obtained sheet gel was mixed with distilled water 100
Then, the resultant was washed at a portion and dried at 60 ° C. for 10 hours to obtain a water-absorbent sheet. The sheet was cut into a size of 3 cm × 3 cm, and the amount of water absorption was measured. As a result, the amount of water absorption was 320 times.

Example 8 The crosslinked polysuccinimide film obtained in Example 2 was treated in the same manner as in Example 7 to obtain a water-absorbent sheet. 3 this sheet
When cut into cm × 3 cm and the amount of water absorption was measured, the amount of water absorption was 260 times.

Example 9 The crosslinked polysuccinimide film obtained in Example 3 was treated in the same manner as in Example 7 to obtain a water-absorbent sheet. 3 this sheet
When cut into cm × 3 cm and the amount of water absorption was measured, the amount of water absorption was 270 times.

Example 10 The crosslinked polysuccinimide film obtained in Example 4 was treated in the same manner as in Example 7 to obtain a water-absorbent sheet. The sheet was cut into a size of 3 cm × 3 cm, and the amount of water absorption was measured. As a result, the amount of water absorption was 190 times.

Example 11 The crosslinked polysuccinimide film obtained in Example 5 was treated in the same manner as in Example 7 to obtain a water-absorbent sheet. The sheet was cut into a size of 3 cm × 3 cm, and the amount of water absorption was measured. As a result, the amount of water absorption was 190 times.

Example 12 When the film of the crosslinked polysuccinimide obtained in Example 6 was treated in the same manner as in Example 7, a water-absorbent sheet was obtained. This sheet was cut into a size of 3 cm × 3 cm, and the amount of water absorption was measured. As a result, the amount of water absorption was 270 times.

Comparative Example 1 Under a nitrogen stream, 5 parts of a polysuccinimide having a molecular weight of 96,000 was dissolved in 30 parts of DMF.
1.8 parts of lysine methyl ester dihydrochloride and 3.1 parts of triethylamine were inserted, and the mixture was stirred at room temperature for 5 hours, stopped stirring, and reacted for 30 hours. Methanol 100
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, and an 8% by weight aqueous solution of sodium hydroxide was added dropwise so as to fall within a range of pH 10 to 11. Then, an aqueous solution of 8% sodium hydroxide solution was further added until the pH of the reaction solution did not decrease. Continued to add. After the pH did not decrease, dilute hydrochloric acid was added until the pH of the reaction solution reached 7. The obtained mixture was discharged into 3,000 parts of acetone, dried and pulverized to obtain 7.6 parts of a water-absorbing polymer. This granular resin (400 parts) was mixed with polylactic acid (600 parts) and injection-molded at 180 ° C. to a thickness of 0.1 mm.
Sheet was obtained. The sheet was cut into a size of 3 cm × 3 cm, and the amount of water absorption was measured. As a result, the amount of water absorption was 25 times.

Comparative Example 3 Crosslinked polyethylene oxide film (Sumikagel R-30G, manufactured by Sumitomo Chemical Co., Ltd.)
Was cut into 3 cm × 3 cm, immersed in distilled water for 30 minutes, and the amount of water absorption was measured. As a result, it was 31 g per 1 g of resin pieces.

[0060]

EFFECTS OF THE INVENTION As an intermediate of a water absorbent used for disposable diapers, agricultural and horticultural applications, etc., a film having biodegradability and capable of being led to a highly water-absorbing film and sheet having excellent water absorbing ability and A sheet can now be obtained.

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Claims (9)

[Claims] 1. Films and sheets comprising a crosslinked polysuccinimide. 2. Films and sheets comprising a crosslinked polysuccinimide and a plasticizer. 3. The method for producing a film and sheet according to claim 1, wherein an uncrosslinked polysuccinimide and a crosslinking agent are simultaneously cast and reacted. 4. The method for producing a film and sheet according to claim 1, wherein a crosslinking agent is reacted after casting the uncrosslinked polysuccinimide solution. 5. The method for producing a film and sheet according to claim 1, wherein a suspension of an organic solvent and / or water containing a crosslinked polysuccinimide is cast. 6. The method for producing a film and sheet according to claim 1, wherein a gel comprising a crosslinked polysuccinimide and an organic solvent and / or water is sheared and cast. 7. The method for producing a film and sheet according to claim 3, wherein the crosslinking agent is a polyamine. 8. The method for producing a film and sheet according to claim 7, wherein a plasticizer is added in the step of producing a film and sheet containing the crosslinked polysuccinimide. 9. A film and a sheet produced by the production method according to claim 3.