WO2020138126A1 - Crosslinkable resin composition and cured product using same - Google Patents

Abstract

A crosslinkable resin composition according to the present invention contains: a modified vinyl alcohol polymer containing a vinyl alcohol unit and a structural unit represented by formula (I); and an anionic polymer electrolyte. In formula (I), X is a carbon-carbon bond or a divalent saturated hydrocarbon group that may be branched and that has 1-10 carbon atoms; Y is a hydrogen atom or a saturated hydrocarbon group that may be branched and that has 1-6 carbon atoms; and Z is a hydrogen atom or a methyl group.

Description

Crosslinkable resin composition and cured product using the same

The present invention relates to a crosslinkable resin composition and a cured product using the same, and more particularly to a crosslinkable resin composition that can provide a material having excellent water absorption and a cured product using the same.

A cross-linked polymer obtained by introducing a cross-linking structure into a water-soluble polymer such as polyvinyl alcohol or poly(meth)acrylic acid is a water-absorbing polymer that is insoluble in water but can retain water to a high degree.

　Water-absorbent polymers are used as materials that make up a wide range of products such as disposable diapers, agricultural materials, ground improvement materials, and contact lenses. In these products, the water-absorbent polymer is required to have both sufficient water absorbency and the property of being moldable into a desired shape.

Among water-absorbent polymers, a cross-linked product of anionic electrolyte polymer such as poly(meth)acrylic acid expresses extremely high water absorption, but it is hard and brittle, and it is pointed out that moldability is poor. On the other hand, non-electrolyte polymers such as polyvinyl alcohol are rich in flexibility and toughness and have good film-forming properties, so that they can be formed into films and fibers, but they are inferior in water absorption compared to electrolyte polymers. It has been pointed out. That is, it has been difficult to achieve both high water absorption and high moldability by using each of the electrolyte polymer and the non-electrolyte polymer alone.

In order to achieve the above compatibility, it has been attempted to combine a non-electrolytic polymer such as polyvinyl alcohol and an electrolytic polymer such as poly(meth)acrylic acid. For example, in Patent Document 1, a radical initiator which is a water-soluble peroxide is added to a mixed aqueous solution of polyvinyl alcohol and polyacrylic acid, and cross-linked through heating and drying to give a predetermined shape such as a coating, a film, or a fiber. A molded crosslinked body is disclosed. Patent Document 2 discloses a hydrogel that is crosslinked by irradiating a mixed aqueous solution of polyvinyl alcohol and poly(meth)acrylic acid with radiation such as an electron beam or γ-ray. Patent Document 3 discloses a hydrous gel in which a mixed aqueous solution of polyvinyl alcohol and poly(meth)acrylic acid is freeze-thawed and crosslinked.

JP-A-1-92226 Japanese Patent Laid-Open No. 2018-9096 JP-A-5-230313

However, it has been pointed out that in crosslinking with peroxides or radiation as described in Patent Documents 1 and 2, physical properties of the crosslinked product are remarkably deteriorated due to concurrent main chain scission of the polymer. Further, since the polymer main chain is randomly crosslinked, it is extremely difficult to control the crosslink density and crosslink points. On the other hand, the crosslinking by freezing and thawing described in Patent Document 3 eliminates the concern of main chain scission, but the energy and time required for the freezing and thawing steps are enormous and industrially difficult to carry out. It has also been pointed out that the gel obtained by freezing and thawing is a physically crosslinked gel and has extremely poor water resistance under high temperature conditions.

The present invention is intended to solve the above problems, and its object is to provide a material having both excellent water absorption and molding processability, and more simply having the water absorption. It is intended to provide a crosslinkable resin composition that can be obtained and a cured product using the same.

The present invention provides a crosslinkable resin composition containing a modified vinyl alcohol polymer containing a vinyl alcohol unit and a structural unit represented by the following formula (I), and an anionic polyelectrolyte:

(In the formula (I), X is a carbon-carbon bond or a divalent saturated hydrocarbon group having 1 to 10 carbon atoms which may be branched, and Y is a hydrogen atom or an optionally branched carbon atom. It is a divalent saturated hydrocarbon group of the numbers 1 to 6 and Z is a hydrogen atom or a methyl group).

In one embodiment, Y in formula (I) is a hydrogen atom.
In one embodiment, X in formula (I) is a carbon-carbon bond.
In one embodiment, the modified vinyl alcohol-based polymer contains the structural unit represented by the formula (I) in a proportion of 0.01 to 3 mol %.
In one embodiment, the anionic polyelectrolyte is a polymer having in the side chain at least one group selected from the group consisting of a carboxylic acid group or a salt thereof and a sulfonic acid group or a salt thereof.
In one embodiment, the anionic polyelectrolyte is poly(meth)acrylic acid.
In one embodiment, the crosslinkable resin composition of the present invention further contains a crosslinking agent.

The present invention is also a cured product containing a crosslinked product of the above-mentioned crosslinkable resin composition.
In one embodiment, the water absorption capacity of the cured product is 5 times or more.
In one embodiment, the elution rate of the cured product is 40% or less.

The present invention is also a method for producing a cured product, which comprises a step of crosslinking the crosslinkable resin composition by irradiating the crosslinkable resin composition with an active energy ray.
The present invention is also a method for producing a cured product, which comprises a step of crosslinking the crosslinkable composition by heating the crosslinkable resin composition.

The present invention is also a water absorbent product containing the above cured product.

According to the present invention, it is possible to easily obtain a cured product that has been crosslinked and made water resistant by using an energy ray or a crosslinking agent without requiring a complicated crosslinking operation. Further, according to the present invention, the crosslinking density can be easily controlled during the crosslinking, and the physical properties (for example, water absorption and water resistance) of the obtained cured product can be improved and the physical properties can be controlled arbitrarily.

The present invention will be described in detail below.

(Crosslinkable resin composition)
The crosslinkable resin composition of the present invention contains a modified vinyl alcohol polymer and an anionic polyelectrolyte. The crosslinkable resin composition of the present invention is a composition that can be crosslinked by application of an active energy ray such as irradiation with a crosslinking agent or UV light described below, and has a property of forming a cured product.

(Modified vinyl alcohol polymer)
The modified vinyl alcohol-based polymer contains a vinyl alcohol unit and a structural unit represented by the following formula (I).

The side chain olefin present in the formula (I) is highly reactive and can be easily crosslinked in the presence of a predetermined crosslinking agent or by application of energy rays. As a result, the modified vinyl alcohol-based polymer has the property of being water-resistant and capable of forming a gel by crosslinking.

In the above formula (I), X is a carbon-carbon bond or an optionally branched divalent saturated hydrocarbon group having 1 to 10 carbon atoms. X is a carbon-carbon bond or a divalent saturated hydrocarbon group having 1 to 6 carbon atoms, which may be branched, from the viewpoint that appropriate modified water-soluble polymer itself can be imparted with water solubility. It is preferable that it is a carbon-carbon bond or a divalent saturated hydrocarbon group having 1 to 4 carbon atoms which may be branched, and most preferably a carbon-carbon bond. The divalent saturated hydrocarbon group is preferably at least one selected from the group consisting of alkylene groups and cycloalkylene groups. That is, for example, the optionally branched divalent saturated hydrocarbon group having 1 to 10 carbon atoms is selected from the group consisting of a branched or linear alkylene group having 1 to 10 carbon atoms and a cycloalkylene group. Is preferably at least one kind. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group and a nonylene group. These alkylene groups may have an alkyl group such as a methyl group and an ethyl group as a branched structure. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group and a cyclononylene group. These cycloalkylene groups may have an alkyl group such as a methyl group and an ethyl group as a branched structure.

Examples of the optionally branched alkylene group having 1 to 10 carbon atoms include methylene group, ethylene group, 1-methylethylene group, 2-methylethylene group, 1,1-dimethylethylene group, 1,2-dimethylethylene. Group, 2,2-dimethylethylene group, 1-ethylethylene group, 2-ethylethylene group, propylene group, 1-methylpropylene group, 2-methylpropylene group, 3-methylpropylene group, 1,1-dimethylpropylene group , 1,2-dimethylpropylene group, 2,2-dimethylpropylene group, 1,3-dimethylpropylene group, butylene group, 1-methylbutylene group, 2-methylbutylene group, 3-methylbutylene group, 4-methylbutylene group Group, 1,1-dimethylbutylene group, 2,2-dimethylbutylene group, 3,3-dimethylbutylene group, 4,4-dimethylbutylene group, 1,2-dimethylbutylene group, 1,3-dimethylbutylene group, 1,4-dimethylbutylene group, 2,3-dimethylbutylene group, 2,4-dimethylbutylene group, 3,4-dimethylbutylene group, 1-ethylbutylene group, 2-ethylbutylene group, 3-ethylbutylene group, 4-ethylbutylene group, 1,1-diethylbutylene group, 2,2-diethylbutylene group, pentylene group, 1-methylpentylene group, 2-methylpentylene group, 3-methylpentylene group, 4-methylpentylene group Examples thereof include len group, 5-methylpentylene group, and hexylene group.

In the above formula (I), Y is a hydrogen atom or an optionally branched saturated hydrocarbon group having 1 to 6 carbon atoms. Y is preferably a hydrogen atom or an optionally branched saturated hydrocarbon group having 1 to 5 carbon atoms from the viewpoint that appropriate water solubility and reactivity can be imparted to the modified vinyl alcohol polymer itself. A hydrogen atom or an optionally branched saturated hydrocarbon group having 1 to 2 carbon atoms is more preferable, and a hydrogen atom is still more preferable. The saturated hydrocarbon group is preferably at least one selected from the group consisting of an alkyl group and a cycloalkyl group. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group and hexyl group. Among them, at least one alkyl group selected from methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group and neopentyl group is preferable. And at least one alkyl group selected from the group consisting of a methyl group and an ethyl group is preferably used. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclohexyl group and the like. Among them, at least one cycloalkyl group selected from the group consisting of a cyclopropyl group, a cyclobutyl group, and a cyclopentyl group is preferably used.

In the above formula (I), Z is a hydrogen atom or a methyl group. Z is preferably a hydrogen atom from the viewpoint that suitable modified water-soluble polymer itself can be imparted with appropriate water solubility.

The content of the structural unit of the formula (I) in the modified vinyl alcohol-based polymer is preferably 0.01 mol% or more, and preferably 0.05 when the total structural unit of the polymer is 100 mol %. It is at least mol%, more preferably at least 0.1 mol%, and even more preferably at least 0.3 mol%. Further, the content of the structural unit of the formula (I) is preferably 3 mol% or less, and preferably 2.5 mol% or less, when all the structural units of the polymer are 100 mol%. It is preferably 2 mol% or less, and more preferably 1.5 mol% or less. When the content of the constituent unit of the above formula (I) is within these ranges, the water resistance of the cured product crosslinked in the presence of a predetermined crosslinking agent or the application of active energy rays is likely to be exhibited. On the other hand, when the content of the constituent unit of the above formula (I) is less than 0.01 mol %, the effect of modifying the vinyl alcohol polymer by the constituent unit of the formula (I) may not be sufficiently exhibited. When the content of the constituent unit of the above formula (I) exceeds 3 mol %, the crystallinity of the vinyl alcohol polymer due to the constituent unit of the formula (I) begins to decrease and the water resistance of the cured product decreases, resulting in hydrophobization. By doing so, water solubility may be deteriorated. The modified polyvinyl alcohol-based polymer may include one or more structural units represented by formula (I). When two or more constituent units are contained, the total content of these two or more constituent units preferably satisfies the above range. The term “constitutional unit” used in the present specification refers to a repeating unit constituting a polymer. For example, a vinyl alcohol unit and a vinyl ester unit described later are also constituent units.

The content of the vinyl alcohol unit in the modified vinyl alcohol-based polymer is not particularly limited, but when all the constituent units in the polymer are 100 mol% from the viewpoint of being able to impart appropriate solubility in water. , Preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 75 mol% or more, still more preferably 80 mol% or more. Further, the content of the vinyl alcohol unit is preferably 99.99 mol% or less, more preferably 99.90 mol% or less, when the total constitutional units in the polymer are 100 mol%.

The vinyl alcohol unit can be derived from the vinyl ester unit by hydrolysis or alcoholysis. Therefore, the vinyl ester unit may remain in the modified vinyl alcohol-based polymer depending on the conditions for converting the vinyl ester unit to the vinyl alcohol unit. Therefore, the modified vinyl alcohol-based polymer may contain a vinyl ester unit other than the constitutional unit represented by the above formula (I).

Examples of the vinyl ester of the vinyl ester unit include vinyl formate, vinyl acetate, vinyl prilopionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versaticate, vinyl caproate, vinyl caprylate, vinyl laurate, palmitin. Examples thereof include vinyl acetate, vinyl stearate, vinyl oleate, and vinyl benzoate. Of these, vinyl acetate is preferable from the industrial viewpoint.

The modified vinyl alcohol polymer may further contain a structural unit other than the structural unit represented by the formula (I), the vinyl alcohol unit and the vinyl ester unit as long as the effects of the present invention can be obtained. The constituent unit is, for example, an unsaturated monomer copolymerizable with a vinyl ester and convertible into a constituent unit represented by the formula (I), or an ethylenically unsaturated monomer copolymerizable with a vinyl ester. It is a structural unit derived from a polymer or the like. Examples of the ethylenically unsaturated monomer include α-olefins such as ethylene, propylene, n-butene, isobutylene and 1-hexene; acrylic acid and salts thereof; methyl acrylate, ethyl acrylate, n-propyl acrylate, Acrylic acid esters such as i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methacrylic acid and its salts; Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, methacrylic acid Methacrylic acid esters such as octadecyl; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts (eg, quaternary) Methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts (for example, quaternary salts); methyl vinyl ether, ethyl vinyl ether, n- Vinyl ethers such as propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, 2,3-diacetoxy-1-vinyloxypropane; acrylonitrile, methacrylonitrile Vinyl cyanides such as; vinyl halides such as vinyl chloride and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl acetate, 2,3-diacetoxy-1-allyloxypropane, allyl chloride Allyl compounds such as; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid and the salts thereof or esters thereof; vinylsilyl compounds such as vinyltrimethoxysilane; isopropenyl acetate and the like.

The arrangement order of the structural unit represented by the formula (I), the vinyl alcohol unit, and any other structural unit in the modified vinyl alcohol-based polymer is not particularly limited, and the modified polyvinyl alcohol-based polymer is a random copolymer. It may be a block copolymer, an alternating copolymer, or the like.

The modified vinyl alcohol-based polymer preferably has a predetermined viscosity average degree of polymerization according to JIS K6726. The modified vinyl alcohol-based polymer according to JIS K6726 has a viscosity average degree of polymerization of preferably 100 to 5,000, more preferably 200 to 4,000. If the viscosity average degree of polymerization is less than 100, the mechanical strength of the film may decrease when the film is formed. When the viscosity average degree of polymerization exceeds 5,000, industrial production of the modified vinyl alcohol polymer may be difficult.

The method for producing the modified vinyl alcohol-based polymer is not particularly limited. For example, a transesterification reaction of a vinyl alcohol-based polymer and an ester compound represented by the following formula (II) (hereinafter referred to as ester compound (II)) The method of doing is simple.

In the above formula (II), X, Y and Z are the same as those defined in the above formula (I), and R is a saturated hydrocarbon group having 1 to 5 carbon atoms. In this method, the vinyl alcohol polymer and the ester compound (II) are mixed with a transesterification reaction catalyst to transesterify the vinyl alcohol unit of the vinyl alcohol polymer and the ester compound (II). The method can be adopted as a preferred embodiment. At that time, the alcohol represented by ROH (R is the same as defined in the above formula (II)) is eliminated from the ester compound (II), but by removing the alcohol out of the reaction system. The reaction between the vinyl alcohol polymer and the ester compound (II) is promoted. From this point of view, the alcohol represented by ROH is preferably a compound having a low boiling point, the carbon number of R is 1 to 5, preferably 1 to 3, and more preferably 1. .. As the saturated hydrocarbon group, at least one selected from the group consisting of an alkyl group and a cycloalkyl group is suitable. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Among them, at least one alkyl group selected from the group consisting of a methyl group, an ethyl group, a propyl group and an isopropyl group is preferably used, and a methyl group is more preferably used. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group and the like. Among them, at least one cycloalkyl group selected from the group consisting of a cyclopropyl group, a cyclobutyl group and a cyclopentyl group is preferably used. As X, Y and Z in the formula (II), those exemplified in the above formula (I) are preferably used.

Examples of the ester compound (II) include methyl methacrylate, methyl acrylate, methyl crotone, methyl 3-methyl-3-butenoate, methyl 4-pentenoate, methyl 2-methyl-4-pentenoate, and 5-hexene. Acid methyl, methyl 3,3-dimethyl-4-pentenoate, methyl 7-octenoate, methyl trans-3-pentenoate, methyl trans-4-pentenoate, ethyl 3-methyl-3-butenoate, 4-pentene Acid ethyl, 2-methyl-4-pentenoate, ethyl 5-hexenoate, ethyl 3,3-dimethyl-4-pentenoate, ethyl 7-octenoate, ethyl trans-3-decenoate, trans-4-decene Ethyl acid and the like can be mentioned. Among them, methyl methacrylate, methyl acrylate, methyl 4-pentenoate, methyl 2-methyl-4-pentenoate, methyl 5-hexenoate, and 3,3-dimethyl-methyl ester are preferred because the transesterification reaction proceeds easily. At least one selected from the group consisting of methyl 4-pentenoate, methyl 7-octenoate, methyl trans-3-pentenoate and methyl trans-4-pentenoate is preferable, and it is excellent in water solubility and energy reactivity. Methyl methacrylate, methyl acrylate, methyl 4-pentenoate, methyl 2-methyl-4-pentenoate, methyl 5-hexenoate, from which a modified polyvinyl alcohol-based polymer having appropriate water solubility can be obtained. And at least one selected from the group consisting of methyl 3,3-dimethyl-4-pentenoate are more preferred, and methyl methacrylate, methyl acrylate, and methyl 3,3-dimethyl-4-pentenoate are most preferred. In the transesterification reaction, two or more kinds of these ester compounds may be used in combination.

The transesterification reaction catalyst is not particularly limited, and examples thereof include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; organic carboxylic acids such as acetic acid, propionic acid, phthalic acid and benzoic acid; methylsulfonic acid, benzenesulfonic acid, p- Organic sulfonic acids such as toluene sulfonic acid and trifluoromethane sulfonic acid; Organic phosphoric acids such as diethyl phosphate and phenyl phosphate; Hydroxylation of alkali metal or alkaline earth metal such as sodium hydroxide, potassium hydroxide and magnesium hydroxide Compounds; carbonates and hydrogen carbonates of alkali metals or alkaline earth metals such as sodium hydrogen carbonate, potassium carbonate, calcium hydrogen carbonate; trilithium phosphate, potassium dihydrogen phosphate, sodium pyrophosphate, alkali metal such as calcium metaphosphate Or alkaline earth metal phosphates and hydrogen phosphates; alkali metal or alkaline earth metal borates such as potassium metaborate, sodium tetraborate, magnesium orthoborate; sodium acetate, potassium acetate, sodium benzoate Alkali metal or alkaline earth metal carboxylates such as magnesium acetate; alkali metal or alkaline earth metal alkoxide compounds or phenoxide compounds such as lithium ethoxide, sodium methoxide, potassium methoxide, magnesium methoxide, sodium phenoxide Oxides of alkali metals or alkaline earth metals such as calcium oxide; ammonia; ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, ammonium carbonate, ammonium hydrogencarbonate, tetramethylammonium methyl Carbonate, tetramethylammonium ethyl carbonate, methyltriethylammonium methylcarbonate, methyltri-n-butylammonium methylcarbonate, methyltri-n-octylmethylcarbonate and other ammonium salts; tetraphenylphosphonium hydroxide, tetramethylphosphonium hydroxide, tetramethylphosphonium methylcarbonate , Phosphonium salts such as methyltri-n-butylphosphonium ethyl carbonate and methyltri-n-octylphosphonium methylcarbonate; primary amines such as n-butylamine, benzylamine, aniline and ethylenediamine; diamines such as diethylamine, methylethylamine, pyrrolidine and N-methyltoluidine. Primary amine; Triethylamine, tri-n-butylamine, N-methyl-N-ethylaniline, 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]-7-undecene, etc. Amine; Nitrogen-containing aromatic heterocyclic compounds such as pyridine, picoline, quinoline, imidazole, pyrimidine, N,N-dimethylaminopyridine; Cadmium compounds such as cadmium chloride, cadmium oxide, cadmium acetate; Tin chloride, tin oxide , Tin acetate, tin octoate, tributyltin, acetylacetone tin (IV) chloride and other tin compounds; lead chloride, lead oxide, lead carbonate, lead tetraacetate and other lead compounds; aluminum chloride, aluminum oxide, aluminum acetate, Aluminum compounds such as aluminum alkoxide; zinc chloride, zinc bromide, zinc iodide, zinc oxide, zinc acetate, zinc trifluoroacetate, zinc stearate, zinc nitrate, zinc carbonate, zinc sulfate, zinc acetylacetone (II), trifluor Zinc (II) methanesulfonate, zinc 2-tetrafluoroborate, zinc-based compounds such as oxo[hexa(trifluoroacetato)]tetrazinc; bismuth-based compounds such as bismuth chloride, bismuth oxide, bismuth acetate; iron chloride , Iron oxides, iron acetate, iron (III) acetylacetone, iron (II) N,N'-bis(salicylidene) ethylenediamine iron (II); cobalt chloride, cobalt oxide, cobalt acetate, cobalt stearate, acetylacetone cobalt (II) ) And other cobalt-based compounds; copper-based compounds such as copper chloride, copper bromide, copper iodide, copper oxide, copper acetate, and copper (II) acetylacetone; chromium chloride, chromium oxide, chromium acetate, chromium (III) acetylacetone, etc. Chromium compounds; molybdenum compounds such as molybdenum chloride, molybdenum oxide, molybdenum acetate, acetylacetone molybdenum (VI) dioxide; manganese compounds such as manganese chloride, manganese oxide, manganese acetate, acetylacetone manganese (II); titanium chloride, oxidation Titanium compounds such as titanium, titanium acetate, alkoxy titanium, titanium lactate, and acetylacetone titanium (VI) oxide; zirconium compounds such as zirconium chloride, zirconium oxide, zirconium acetate, and acetylacetone zirconium (IV); hafnium chloride, hafnium oxide, and trifluoride. Hafnium-based compounds such as hafnium (IV) methanesulfonate; lanthanum chloride, Lanthanum compounds such as lanthanum oxide, lanthanum acetate, lanthanum nitrate, lanthanum alkoxide, acetylacetone lanthanum (III) and lanthanum (III) trifluoromethanesulfonate; germanium compounds such as germanium chloride and germanium oxide; enzymes such as lipase; It is preferably used. Among them, from the viewpoint of reactivity and hue of the modified polyvinyl alcohol-based polymer obtained, inorganic acid, organic carboxylic acid, organic sulfonic acid, organic phosphoric acid, hydroxide of alkali metal or alkaline earth metal, alkali metal or alkali Earth metal carbonates and hydrogen carbonates, alkali metal or alkaline earth metal phosphates and hydrogen phosphates, alkali metal or alkaline earth metal carboxylates, alkali metal or alkaline earth metal alkoxide systems Compounds or phenoxide compounds, ammonium salts, phosphonium salts, aluminum compounds, zinc compounds, bismuth compounds, titanium compounds, zirconium compounds, lanthanum compounds are more preferable, inorganic acids, organic carboxylic acids, organic sulfonic acids, alkalis Metal or alkaline earth metal hydroxides, alkali metal or alkaline earth metal carbonates and hydrogen carbonates, alkali metal or alkaline earth metal carboxylates, alkali metal or alkaline earth metal alkoxide compounds, ammonium Salts, zinc compounds, titanium compounds, zirconium compounds, lanthanum compounds are more preferable, and alkali metal or alkaline earth metal carboxylates, ammonium salts, and zinc compounds are even more preferable.

The amount of the transesterification reaction catalyst added is not particularly limited, but is preferably 0.01 part by mass to 30 parts by mass with respect to 100 parts by mass of the vinyl alcohol polymer. If the amount of the transesterification reaction catalyst added is less than 0.01 part by mass, the reaction rate may be lowered. When the amount of the transesterification reaction catalyst added exceeds 30 parts by mass, it becomes difficult to remove the catalyst residue, and the hue and thermal stability of the resulting modified vinyl alcohol-based polymer may decrease.

The addition amount of the ester compound (II) is not particularly limited, and is preferably 0.1 part by mass to 1000 parts by mass, more preferably 5 parts by mass to 500 parts by mass with respect to 100 parts by mass of the vinyl alcohol polymer. .. If the amount added is less than 0.1 parts by mass, the reaction rate may decrease. If the addition amount exceeds 1000 parts by mass, it may be difficult to remove the ester compound remaining after the reaction.

The transesterification reaction may be carried out in a state in which the vinyl alcohol-based polymer, the ester compound (II) and the transesterification reaction catalyst are mixed, and for example, the molten vinyl alcohol-based polymer is mixed with the ester compound (II) and the ester compound (II). Method of mixing and reacting transesterification reaction catalyst; Method of dissolving ester compound (II) and transesterification catalyst and reacting in slurry state in solvent in which vinyl alcohol polymer is not dissolved; Vinyl alcohol system And the like, in which the polymer, the ester compound (II) and the transesterification reaction catalyst are all uniformly dissolved in the solution. These methods can be appropriately selected by those skilled in the art in consideration of reactivity, isolation of the resulting modified vinyl alcohol-based polymer, and the like.

When the transesterification reaction is carried out in a slurry state or a homogeneous solution state, the concentration of the vinyl alcohol polymer during the reaction is not particularly limited, but it is preferably 1% by mass to 50% by mass, more preferably 2% by mass to 40% by mass. It is a mass%, and more preferably 3 mass% to 30 mass%. If the concentration is less than 1% by mass, it may be too dilute to reduce the reaction rate, and if the concentration exceeds 50% by mass, poor stirring may occur in the reaction system.

The solvent used in the transesterification reaction is not particularly limited, and examples thereof include water; alcohols such as methanol, ethanol, propanol and butanol; aliphatic or alicyclic hydrocarbons such as n-hexane, n-pentane and cyclohexane; benzene. , Aromatic hydrocarbons such as toluene; aliphatic or aromatic halides such as chloroform, chlorobenzene and dichlorobenzene; nitriles such as acetonitrile and benzonitrile; diethyl ether, diphenyl ether, anisole, 1,2-dimethoxyethane, 1 , Ethers such as 4-dioxane; ketones such as acetone, methyl isopropyl ketone and methyl isobutyl ketone; esters such as ethyl acetate and ethyl propionate; N-alkyl lactams such as N-methyl-2-pyrrolidone; N , N-dimethylformamide, N,N-dimethylacetamide and other N,N-dialkylamides; dimethyl sulfoxide and other sulfoxides; sulfolane and other sulfolanes; Of these, aprotic polar solvents such as nitriles, ethers, ketones, esters, N-alkyllactams, N,N-dialkylamides, sulfoxides and sulfolanes are preferable, and N-alkyllactams, N , N-dialkylamides and sulfoxides are more preferable.

The reaction temperature in the transesterification reaction is not particularly limited, but in order to properly remove the alcohol desorbed from the ester compound (II) to the outside of the reaction system, it is preferably the boiling point of the alcohol or higher. From such a viewpoint, 20° C. to 200° C. is preferable, 30° C. to 180° C. is more preferable, 40° C. to 170° C. is further preferable, and 50° C. to 150° C. is further more preferable. The reaction system may be depressurized if necessary in order to lower the boiling point of the alcohol desorbed from the ester compound. The pressure in the reaction system is preferably 5 kPa to 99 kPa, more preferably 8 kPa to 97 kPa, and further preferably 10 kPa to 95 kPa.

(Anionic polyelectrolyte)
The anionic polyelectrolyte is a natural or synthetic polymer and is, for example, a thermoplastic resin having a predetermined functional group in the side chain, a polysaccharide, a polypeptide, or a salt thereof. Examples of the functional group that may be contained in the anionic polyelectrolyte include a carboxylic acid group or a salt thereof (carboxylate group), a sulfonic acid or a salt thereof (sulfonate group), and a combination thereof. ..

Examples of the anionic polyelectrolyte include heat of poly(meth)acrylic acid, polystyrene sulfonic acid, maleic acid-based copolymer, itaconic acid-based copolymer, 2-acrylamido-2-methylpropanesulfonic acid copolymer, and the like. Plastic resins; polysaccharides such as carboxymethyl cellulose, sodium dextran sulfate, alginic acid, hyaluronic acid, heparin, heparan sulfate, chondroitin sulfate, cellouronic acid; polypeptides such as polyaspartic acid, polyglutamic acid, cellouronic acid; and salts thereof; and A combination thereof can be mentioned. Poly(meth)acrylic acid is preferable because it can be made highly resistant to water together with the modified vinyl alcohol polymer.

In the crosslinked resin composition of the present invention, the mixing ratio of the modified vinyl alcohol polymer and the anionic polyelectrolyte is not particularly limited, but is preferably 1/99 to 99/1, and more preferably based on the mass. It is 10/90 to 90/10, and more preferably 20/80 to 80/20. By containing the modified vinyl alcohol-based polymer and the anionic polyelectrolyte in a mass ratio in such a range, the resin composition obtained does not require a complicated crosslinking operation, and the presence of a predetermined crosslinking agent is present. A crosslinked structure can be easily formed underneath or by applying an active energy ray.

(Crosslinking agent)
The crosslinkable resin composition of the present invention may contain a crosslinking agent known in the art. The cross-linking agent preferably includes a compound having two or more thiol groups in one molecule, a compound having two or more amino groups in one molecule, and the like. Examples of the compound having two or more thiol groups in one molecule include 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,5 -Pentanedithiol, 1,6-hexanedithiol, 1,10-decanedithiol, 2,3-dihydroxy-1,4-butanedithiol, ethylene bis(thioglycolate), ethylene glycol bis(3-mercaptopropionate) , 1,4-butanediol bis(thioglycolate), 2,2'-thiodiethanethiol, 3,6-dioxa-1,8-octanedithiol (DODT), 3,7-dithia-1,9- Nonanedithiol, 1,4-benzenedithiol, trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tris (thioglycolate), pentaerythritol tetrakis (mercaptoacetate), dipentaerythritol hexakis (3- Mercaptopropionate), thiocol (manufactured by Toray Fine Chemical Co., Ltd.) and the like. Examples of the compound having two or more amino groups in one molecule include ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 2,2-dimethyl-1,3-propanediamine, 1, 2-diamino-2-methylpropane, 2-methyl-1,3-propanediamine, 1,2-diaminobutane, 1,4-diaminobutane, 1,3-diaminopentane, 1,5-diaminopentane, 1, 6-diaminohexane, 2-methyl-1,5-diaminopentane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1-methyl-1,8-diaminooctane, 1,10 -Diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, bis(3-aminopropyl)ether, 1,2-bis(3-aminopropoxy)ethane, 1,3-bis(3-aminopropoxy) )-2,2-Dimethylpropane, 2,2'-oxybis(ethylamine), 1,3-diamino-2-propanol, α,ω-bis(3-aminopropyl) polyethylene glycol ether, 1,2-diaminocyclohexane 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 4-(2-aminoethyl)cyclohexylamine, isophoronediamine , 1,4-phenylenediamine and the like.

The content of the cross-linking agent is not particularly limited, but is, for example, preferably 0.1 parts by mass to 20 parts by mass, more preferably 0.5 parts by mass to 10 parts by mass with respect to 100 parts by mass of the modified vinyl alcohol polymer. It is a mass part. If the content of the cross-linking agent is less than 0.1 parts by mass, the cross-linked structure is not sufficiently formed in the resin composition, and there is a possibility that the obtained cured product may not have satisfactory water resistance. When the content of the cross-linking agent exceeds 20 parts by mass, the cross-linking in the obtained cured product does not proceed further, and the productivity may be rather lowered.

(Photopolymerization initiator)
Alternatively, the crosslinkable resin composition of the present invention may contain a photopolymerization initiator known in the art in place of the above crosslinker. The photopolymerization initiator is not particularly limited, but is, for example, a propiophenone compound such as 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone; 4′-phenoxy-2,2- Dichloroacetophenone, 4'-t-butyl-2,2,2-trichloroacetophenone, 2,2-diethoxyacetophenone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-1-(4 '-Dodecylphenyl)-1-propanone, 1-[4'-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-4' -Acetophenone compounds such as methylthio-2-morpholinopropiophenone; benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and benzyl dimethyl ketal; benzophenone, o-benzoyl methyl benzoate, 4-phenylbenzophenone, 2-chlorobenzophenone, 2,2'-dichlorobenzophenone, 4-hydroxybenzophenone, 4,4'-dihydroxybenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, 3,3'-dimethyl- Benzophenone compounds such as 4-methoxybenzophenone, Michler's ketone [4,4′-bis(dimethylamino)benzophenone], 4,4′-bis(diethylamino)benzophenone; 2-chlorothioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone , 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone and other thioxanthone compounds; such as 9,10-phenanthrenequinone, camphorquinone (2,3-bornanedione) and 2-ethylanthraquinone Examples thereof include quinone compounds; 2,4,6-trimethylbenzoyldiphenylphosphine oxide; benzyl and the like.

The photopolymerization initiator is not particularly limited, but is, for example, preferably 0.1 parts by mass to 10 parts by mass, more preferably 0.2 parts by mass to 5 parts by mass with respect to 100 parts by mass of the modified vinyl alcohol polymer. It is a department. When the content of the photopolymerization initiator is less than 0.1 parts by mass, for example, even if the resin composition is irradiated with UV light, a crosslinked structure is not sufficiently formed, and the resulting cured product has satisfactory water resistance. May not be achieved. When the content of the photopolymerization initiator is more than 10 parts by mass, the crosslinking in the obtained cured product does not proceed further, and the productivity may rather be lost.

(Other additives)
Further, the crosslinkable resin composition of the present invention may contain other additives known in the art. Examples of such other additives include fillers, processing stabilizers, weather resistance stabilizers, colorants, UV light absorbers, light stabilizers, antioxidants, antistatic agents, flame retardants, plasticizers. , Lubricants, fragrances, defoamers, deodorants, release agents, mold release agents, reinforcing agents, fungicides, preservatives, crystallization rate retarders, and other water-soluble resins, and combinations thereof. To be

In the crosslinkable resin composition of the present invention, the content of the above-mentioned other additives is not particularly limited, and an amount that does not impair the efficiency of the present invention can be arbitrarily set by those skilled in the art.

(Cured product)
The hardened|cured material of this invention contains the crosslinked body of the said crosslinkable resin composition. The crosslinked product of the crosslinkable resin composition is represented by the above formula (I) in which the modified vinyl alcohol-based polymer and the anionic polyelectrolyte contained in the crosslinkable resin composition constitute the modified vinyl alcohol-based polymer. It is chemically or physically integrated by crosslinking based on the constitutional unit.

The cured product of the present invention has excellent water resistance. The degree of such water resistance can be evaluated by, for example, measuring the elution rate of the obtained crosslinked product.

The dissolution rate of the crosslinked product is calculated as follows: First, the mass (W1) of a given crosslinked product at the (untreated) stage where the evaluation was started is measured, and then the crosslinked product is heated at 80° C. for 24 hours. The mass (W2) after vacuum drying was measured, and from W1 and W2, the solid content (TS) of the crosslinked product was calculated by the following formula:
TS (mass %)=100×W2/W1
Calculated according to. Next, the predetermined crosslinked product at the (untreated) stage when the evaluation was started was immersed in pure water at room temperature (25°C) for 24 hours, taken out from water, vacuum dried at 80°C for 24 hours, and then mass ( W3) was measured and finally using W1, TS and W3 obtained above, the following formula:
Dissolution rate (mass %)=100−{W3/(W1×TS/100)}×100
The dissolution rate can be calculated according to

The cured product of the present invention preferably has an elution rate of 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and most preferably 25% by mass or less. When the cured product of the present invention satisfies the elution ratio in the above range, elution of the constituents is prevented before and after immersion in the water, in other words, it has excellent water resistance to the water. You can see that

The cured product of the present invention has excellent water absorption. The degree of such water absorption can be evaluated, for example, by measuring the water absorption capacity of the obtained crosslinked product.

The water absorption capacity of the crosslinked product was measured by immersing the predetermined crosslinked product in water (pure water) at 25°C for 3 hours, then removing the water from the water and wiping off the water on the surface (W4). Then, the mass (W5) of the crosslinked product after vacuum drying at 80° C. for 24 hours was measured.
Water absorption ratio (times) = W4/W5
Can be calculated according to

The cured product of the present invention preferably has a water absorption capacity of 5 times or more, more preferably 7 times or more, still more preferably 10 times or more. The upper limit of the water absorption capacity of the cured product of the present invention is not particularly limited, but is, for example, 2000 times or less and 1000 times or less. Since the cured product of the present invention satisfies the water absorption capacity in the above range, it is understood that the constituents have the ability to absorb a large amount of water when immersed in the water.

The cured product of the present invention can be produced, for example, as follows using the above crosslinkable resin composition.

First, the case where the crosslinkable resin composition contains a photopolymerization initiator together with the modified polyvinyl alcohol-based polymer and the anionic polyelectrolyte will be described.

In such a case, the crosslinkable resin composition is irradiated with α-rays, γ-rays, electron beams, i-rays, active energy rays such as UV rays, and particularly preferably UV rays.

The irradiation conditions of UV light are not necessarily limited because they vary depending on the amount of the crosslinkable resin composition used and the content of the contents thereof, and appropriate irradiation conditions (for example, irradiation intensity and irradiation time) can be determined by those skilled in the art. It can be appropriately selected. Irradiation of the UV light to the crosslinkable resin composition may be performed continuously or intermittently.

By irradiating the crosslinkable resin composition with UV light, the modified vinyl alcohol-based polymer and the anionic polyelectrolyte contained in the composition constitute the modified vinyl alcohol-based polymer and have the above formula (I). Crosslinking based on the constitutional unit represented by is chemically or physically integrated to form a predetermined crosslinked body. In this way, the cured product of the present invention can be obtained.

On the other hand, a case where the crosslinkable resin composition contains a crosslinker together with the modified vinyl alcohol polymer and the anionic polyelectrolyte will be described.

In such a case, the crosslinkable resin composition is heated.

The heating conditions are not necessarily limited because they vary depending on the amount of the crosslinkable resin composition used, the content of those contents, etc., and appropriate heating conditions (for example, heating temperature and heating time) are appropriately selected by those skilled in the art. obtain. The heating of the crosslinkable resin composition may be performed continuously or intermittently.

By heating the crosslinkable resin composition, the modified polyvinyl alcohol-based polymer and the anionic polyelectrolyte contained in the composition are structural units represented by the above formula (I) that constitute the modified polyvinyl alcohol-based polymer. Based on the cross-linking, they are chemically or physically integrated to form a predetermined cross-linked product. In this way, the cured product of the present invention can be obtained.

The cured product of the present invention is not particularly limited, but by utilizing its excellent water absorption and water resistance, hygiene products (for example, diapers and sanitary products), medical-related products (for example, dressing materials for wound protection), agriculture/ Gardening materials (eg soil water retention agent, seedling sheet, seed coating material), food packaging materials (eg freshness retention film, dew condensation prevention sheet, barrier coating material), pet related products (eg pet sheet, cat sand), electricity It can be used as a material for forming various industrial products such as related materials (for example, water-stopping materials for communication cables, building materials (for example, wallpaper for preventing dew condensation)).

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, "%" and "parts" in Examples and Comparative Examples represent "% by mass" and "parts by mass", respectively, unless otherwise specified.

(Calculation of denaturation rate)
Using a nuclear magnetic resonance apparatus “LAMBDA 500” manufactured by JEOL Ltd., ¹ H-NMR of the modified vinyl alcohol polymer was measured at room temperature, and an integrated value of a peak (5.0 to 7.5 ppm) derived from an olefin proton was obtained. The denaturation rate was calculated from For example, in Example 1, the modification rate was calculated from the integrated value of the peaks derived from the olefin protons appearing at 5.6 ppm and 6.0 ppm.

(Evaluation of water resistance)
The mass (W1) of the crosslinked products obtained in Examples and Comparative Examples was measured, and then the mass (W2) of the crosslinked product after vacuum drying at 80° C. for 24 hours was measured to obtain the crosslinked product from W1 and W2. The solid content of the body (TS) is the following formula:
TS (mass %)=100×W2/W1
Was calculated according to. Next, the predetermined crosslinked product at the (untreated) stage when the evaluation was started was immersed in pure water at room temperature (25°C) for 24 hours, taken out from water, vacuum dried at 80°C for 24 hours, and then mass ( W3) was measured, and finally the elution rate was calculated according to the following formula using W1, TS and W3 obtained above, which was used as an index of crosslinking water resistance. Note that the lower the elution rate, the higher the water resistance.
Dissolution rate (mass %)=100−{W3/(W1×TS/100)}×100

(Evaluation of water absorption)
The cross-linked products obtained in Examples and Comparative Examples were immersed in pure water at room temperature (25° C.) for 3 hours, taken out from water, and the mass (W4) after wiping off surface water was measured. Then, the mass (W5) of the crosslinked product after vacuum drying at 80° C. for 24 hours was measured. From the obtained mass, a water absorption capacity was calculated according to the following formula, and this water absorption capacity was used as an index of water absorption. The higher the water absorption ratio, the higher the water absorption.
Water absorption ratio (times) = W4/W5

(Synthesis example 1)
In a reactor equipped with a stirrer, a reflux pipe, and an addition port, 400.0 parts by mass of dehydrated dimethylsulfoxide (hereinafter, abbreviated as DMSO), and a base polymer, a polyvinyl alcohol resin previously vacuum dried at 80° C. for 24 hours. (Manufactured by Kuraray Co., Ltd., polymerization degree 1700, saponification degree 98.5 mol %) 100 parts by mass was added, and a uniform solution was obtained by heating to 100° C. with stirring. Next, 40.0 parts by mass of methyl 3,3-dimethylpentenoate was added, and the mixture was further stirred until it became uniform.

After that, 0.4 parts by mass of tetramethylammonium methyl carbonate was added as a transesterification catalyst, reacted for 5 hours, and then allowed to cool to room temperature. DMSO was added to the reaction solution to dilute it, then the polymer was isolated by dropping it in methanol and dried at 40° C. and 1.3 Pa for 12 hours to obtain a modified vinyl alcohol-based polymer (modified PVOH-1). Got Table 1 shows the characteristics of the modified PVOH-1 obtained in this synthesis example.

(Synthesis example 2)
In a reactor equipped with a stirrer, a reflux tube, and an addition port, 36 parts by mass of DMSO, a polyvinyl alcohol resin previously vacuum-dried as a base polymer at 80° C. for 24 hours (manufactured by Kuraray Co., Ltd., viscosity average degree of polymerization 2400, saponification) 98.5 parts by mass (98.5 mol%) and heated to 100° C. with stirring to obtain a uniform solution. Next, 6 parts by mass of methyl methacrylate (MMA) and 0.1 parts by mass of phenothiazine were added, and the mixture was further stirred until it became uniform. Then, 0.17 parts by mass of sodium acetate was added as a transesterification catalyst, reacted for 1.5 hours, and then allowed to cool to room temperature. DMSO was added to the reaction solution to dilute it, and the solution was added dropwise to methanol to isolate the polymer, which was then dried at 40° C. and 1.3 Pa for 12 hours to obtain a modified polyvinyl alcohol polymer (modified PVOH-2). Got The characteristics of the modified PVOH-2 obtained in this synthesis example are shown in Table 1.

(Synthesis example 3)
In a reactor equipped with a stirrer, a reflux tube, and an addition port, 36 parts by mass of DMSO, a polyvinyl alcohol resin previously vacuum-dried as a base polymer at 80° C. for 24 hours (Kuraray Co., Ltd., viscosity average degree of polymerization 1700, saponification) 98.5 parts by mass (98.5 mol%) and heated to 100° C. with stirring to obtain a uniform solution. Next, 6 parts by mass of methyl methacrylate (MMA) and 0.1 parts by mass of phenothiazine were added, and the mixture was further stirred until it became uniform. Then, 0.17 parts by mass of sodium acetate was added as a transesterification catalyst, reacted for 20 minutes, and then allowed to cool to room temperature. DMSO was added to the reaction solution to dilute it, and the solution was added dropwise to methanol to isolate the polymer, which was then dried at 40° C. and 1.3 Pa for 12 hours to obtain a modified vinyl alcohol polymer (modified PVOH-3). Got Table 1 shows the characteristics of the modified PVOH-3 obtained in this synthesis example.

(Synthesis example 4)
In a reactor equipped with a stirrer, a reflux tube, and an addition port, 36 parts by mass of DMSO, a polyvinyl alcohol resin previously vacuum-dried as a base polymer at 80° C. for 24 hours (manufactured by Kuraray Co., Ltd., viscosity average degree of polymerization: 500, saponification) 9 parts by mass (88 mol %) and heated to 100° C. with stirring to obtain a uniform solution. Next, 6 parts by mass of methyl acrylate (MA) and 0.1 parts by mass of phenothiazine were added and further stirred until uniform. Then, 1.8 parts by mass of zinc nitrate hexahydrate was added as a transesterification catalyst, reacted for 5 hours, and then allowed to cool to room temperature. DMSO was added to the reaction solution to dilute it, and the solution was added dropwise to methanol to isolate the polymer, which was then dried at 40° C. and 1.3 Pa for 12 hours to give a modified vinyl alcohol polymer (modified PVOH-4). Got Table 1 shows the characteristics of the modified PVOH-4 obtained in this synthesis example.

(Synthesis example 5)
In a reactor equipped with a stirrer, a reflux tube, and an addition port, 36 parts by mass of DMSO, a polyvinyl alcohol resin previously vacuum-dried as a base polymer at 80° C. for 24 hours (Kuraray Co., Ltd., viscosity average degree of polymerization 1700, saponification) 99.5 parts by weight (99.5 mol %) and heated to 100° C. with stirring to obtain a uniform solution. Next, 6 parts by mass of methyl methacrylate (MMA) and 0.1 parts by mass of phenothiazine were added, and the mixture was further stirred until it became uniform. Then, 0.17 parts by mass of sodium acetate was added as a transesterification catalyst, reacted for 5 hours, and then allowed to cool to room temperature. DMSO was added to the reaction solution to dilute it, and the solution was added dropwise to methanol to isolate the polymer, which was then dried at 40° C. and 1.3 Pa for 12 hours to obtain a modified polyvinyl alcohol polymer (modified PVOH-5). Got Table 1 shows the characteristics of the modified PVOH-5 obtained in this synthesis example.

(Synthesis example 6)
As a base polymer, polyvinyl alcohol resin (manufactured by Kuraray Co., Ltd., viscosity average degree of polymerization 1700, degree of saponification 98.5 mol%) was directly used as PVOH-6. The characteristics of PVOH-6 obtained in this synthesis example are shown in Table 1.

(Example 1)
To 1 part by mass of a polyacrylic acid aqueous solution (168-07375, 25% aqueous solution manufactured by Wako Pure Chemical Industries, Ltd.), 1.5 parts by mass of ion-exchanged water was added, and they were mixed sufficiently until they became uniform. Next, 2.5 parts by mass of a 10% aqueous solution of modified PVOH-1 obtained in Synthesis Example 1 was added and mixed until uniform to obtain a mixed solution containing modified PVOH-1 and polyacrylic acid. To the resulting mixed solution, 5 parts by mass of ion-exchanged water was added to prepare a 5% by mass aqueous solution, and 2-hydroxy-4′-(2-hydroxyethoxy)-2 as a photopolymerization initiator was added thereto. -Methylpropiophenone (HEMP) was added in an amount of 0.005 parts by mass and stirred until completely dissolved to prepare an aqueous solution (E1) which is a crosslinkable resin composition. Next, this aqueous solution (E1) was cast onto a 15 cm×15 cm mold formed by bending the ends of a polyethylene terephthalate film, and the solvent was sufficiently volatilized at room temperature under atmospheric pressure to give a thickness of about 100 μm. I got a film of. The obtained film was irradiated with UV light at an intensity of 10,000 mJ/cm ² to obtain a crosslinked film (SE1). Table 2 shows the evaluation results of the obtained crosslinked film (SE1).

(Example 2)
2.25 parts by mass of ion-exchanged water was added to 0.25 parts by mass of polymethacrylic acid (00578-50 manufactured by Wako Pure Chemical Industries, Ltd.), and they were mixed sufficiently until they were completely dissolved. Next, 2.5 parts by mass of a 10% aqueous solution of modified PVOH-2 obtained in Synthesis Example 2 was added and mixed until uniform to obtain a mixed solution containing modified PVOH-2 and polymethacrylic acid. 0.005 parts by mass of HEMP as a photopolymerization initiator was added to the obtained mixed liquid and stirred until completely dissolved to prepare an aqueous solution (E2) which is a crosslinkable resin composition. Then, this aqueous solution (E2) was transferred to a petri dish having a diameter of 3 cm and a thickness of 1 cm, and UV light was irradiated from above the petri dish at an intensity of 3000 mJ/cm ² to obtain a crosslinked gel (SE2). The evaluation results of the obtained crosslinked gel (SE2) are shown in Table 2.

(Example 3)
To 1 part by mass of an aqueous polyacrylic acid solution (168-07375, 25% aqueous solution manufactured by Wako Pure Chemical Industries, Ltd.), 1.4 parts by mass of ion-exchanged water was added, and 0.11 parts by mass of 8N KOH aqueous solution was added, Mix well until uniform. Next, 2.5 parts by mass of a 10% aqueous solution of modified PVOH-3 obtained in Synthesis Example 3 was added and mixed until uniform to obtain a mixed solution containing modified PVOH-3 and polyacrylic acid. To the obtained mixed liquid, 5 parts by mass of ion-exchanged water was added to prepare a 5% by mass aqueous solution, and 0.005 parts by mass of HEMP as a photopolymerization initiator was added thereto and stirred until completely dissolved. Thus, an aqueous solution (E3) which is a crosslinkable resin composition was prepared. Then, a crosslinked film (SE3) was obtained in the same manner as in Example 1 except that this aqueous solution (E3) was used and the intensity of the irradiated UV light was changed to 3000 mJ/cm ² . Table 2 shows the evaluation results of the obtained crosslinked film (SE3).

(Example 4)
To 0.2 parts by mass of sodium alginate (manufactured by Wako Pure Chemical Industries, 191-09965), 1.8 parts by mass of ion-exchanged water was added, and they were sufficiently mixed until completely dissolved. Next, 3 parts by mass of a 10% aqueous solution of modified PVOH-4 obtained in Synthesis Example 4 was added and mixed until uniform to obtain a mixed solution containing modified PVOH-4 and alginic acid. 0.005 parts by mass of HEMP was added to the obtained mixed liquid and stirred until completely dissolved to prepare an aqueous solution (E4) which is a crosslinkable resin composition. Then, a crosslinked gel (SE4) was obtained in the same manner as in Example 1 except that this aqueous solution (E4) was used and the intensity of the irradiated UV light was changed to 3000 mJ/cm ² . Table 2 shows the evaluation results of the obtained crosslinked gel (SE4).

(Example 5)
To 1.4 parts by mass of an aqueous polyacrylic acid solution (168-07375, Wako Pure Chemical Industries, 25% aqueous solution), 3.0 parts by mass of ion-exchanged water was added, and 0.154 parts by mass of 8N KOH aqueous solution was added. And mixed well until uniform. Next, 1.5 parts by mass of a 10% aqueous solution of modified PVOH-2 obtained in Synthesis Example 2 was added and mixed until uniform to obtain an aqueous solution containing modified PVOH-2 and polyacrylic acid. 5 parts by mass of ion-exchanged water was added to the obtained mixed solution to prepare a 5% by mass aqueous solution, and 3,6-dioxa-1,8-octanedithiol (DODT) 0.014 was added thereto as a crosslinking agent. Parts by mass were added and stirred until completely dissolved to prepare an aqueous solution (E5) which is a crosslinkable resin composition. Next, this aqueous solution (E5) was cast on a 15 cm×15 cm mold formed by bending the ends of a polyethylene terephthalate film, and the solvent was sufficiently volatilized at room temperature under atmospheric pressure to give a thickness of about 100 μm. I got a film of. The obtained film was heat-treated at 120° C. for 10 minutes to obtain a crosslinked film (SE5). Table 2 shows the evaluation results of the obtained crosslinked film (SE5).

(Example 6)
1.4 parts by mass of ion-exchanged water was added to 1 part by mass of a polyacrylic acid aqueous solution (manufactured by Wako Pure Chemical Industries, 168-07375, 25% aqueous solution), and 0.055 parts by mass of an 8N KOH aqueous solution was added. , Mixed well until uniform. Next, 2.5 parts by mass of a 10% aqueous solution of modified PVOH-2 obtained in Synthesis Example 2 was added and mixed until uniform to obtain a mixed solution containing modified PVOH-2 and polyacrylic acid. To the obtained mixed liquid, 0.01 part by mass of DODT was added as a cross-linking agent, stirred until uniform, and 0.011 parts by mass of triethylamine (Et ₃ N) was added to confirm that the mixture became uniform. Then, an aqueous solution (E6) which is a crosslinkable resin composition was prepared. Next, this aqueous solution (E6) was immediately transferred to a petri dish having a diameter of 3 cm and a thickness of 1 cm, heated to 80° C. and heated for 1 hour to obtain a crosslinked gel (SE6). Table 2 shows the evaluation results of the obtained crosslinked gel (SE6).

(Example 7)
To 0.2 parts by mass of an aqueous solution of polyacrylic acid (168-07375, Wako Pure Chemical Industries, 25% aqueous solution), 0.28 parts by mass of ion-exchanged water was added, and 0.022 parts by mass of 8N KOH aqueous solution was added. And mixed well until uniform. Next, 4.5 parts by mass of a 10% aqueous solution of modified PVOH-3 obtained in Synthesis Example 3 was added and mixed until uniform to obtain a mixed solution containing modified PVOH-3 and polyacrylic acid. To the obtained mixed liquid, 5 parts by mass of ion-exchanged water was added to prepare a 5% by mass aqueous solution, and 0.005 parts by mass of HEMP as a photopolymerization initiator was added thereto and stirred until completely dissolved. Thus, an aqueous solution (E7) which is a crosslinkable resin composition was prepared. Next, a crosslinked film (SE7) was obtained in the same manner as in Example 1 except that this aqueous solution (E7) was used and the intensity of the irradiated UV light was changed to 1500 mJ/cm ² . Table 2 shows the evaluation results of the obtained crosslinked film (SE7).

(Example 8)
To 1.4 parts by mass of an aqueous polyacrylic acid solution (168-07375, Wako Pure Chemical Industries, 25% aqueous solution), 3.0 parts by mass of ion-exchanged water was added, and 0.154 parts by mass of 8N KOH aqueous solution was added. And mixed well until uniform. Next, 1.5 parts by mass of a 10% aqueous solution of modified PVOH-5 obtained in Synthesis Example 5 was added and mixed until uniform to obtain a mixed solution containing modified PVOH-5 and polyacrylic acid. To the obtained mixed liquid, 5 parts by mass of ion-exchanged water was added to prepare a 5% by mass aqueous solution, and 0.005 parts by mass of HEMP as a photopolymerization initiator was added thereto and stirred until completely dissolved. Thus, an aqueous solution (E8) which is a crosslinkable resin composition was prepared. Then, a crosslinked film (SE8) was obtained in the same manner as in Example 1 except that this aqueous solution (E8) was used and the intensity of the irradiated UV light was changed to 3000 mJ/cm ² . Table 2 shows the evaluation results of the obtained crosslinked film (SE8).

(Comparative Example 1)
1.4 parts by mass of ion-exchanged water was added to 1 part by mass of a polyacrylic acid aqueous solution (manufactured by Wako Pure Chemical Industries, 168-07375, 25% aqueous solution), and 0.11 parts by mass of an 8N KOH aqueous solution was added to obtain a uniform mixture. Mix well until Next, 2.5 parts by mass of a 10% aqueous solution of PVOH-6 obtained in Synthesis Example 6 was added and mixed until uniform to obtain a mixed solution containing PVOH-6 and polyacrylic acid. To the obtained mixed liquid, 5 parts by mass of ion-exchanged water was added to prepare a 5% by mass aqueous solution, and 0.005 parts by mass of HEMP as a photopolymerization initiator was added thereto and stirred until completely dissolved. Thus, an aqueous solution (C1) which is a resin composition was prepared. Then, a film (SC1) was obtained in the same manner as in Example 1 except that this aqueous solution (C1) was used. Table 2 shows the evaluation results of the obtained film (SC1).

(Comparative example 2)
In the same manner as in Comparative Example 1, a mixed solution containing PVOH-6 and polyacrylic acid was obtained. A predetermined amount of ion-exchanged water is added to the obtained mixed liquid to prepare a 5% by mass aqueous solution, and 0.01 part by mass of DODT as a crosslinking agent is added thereto, and the mixture is stirred until completely dissolved to obtain a resin composition. To prepare an aqueous solution (C2). Then, a film (SC2) was obtained in the same manner as in Example 5 except that this aqueous solution (C2) was used. Table 2 shows the evaluation results of the obtained film (SC2).

(Comparative example 3)
In the same manner as in Comparative Example 1, a mixed solution containing PVOH-6 and polyacrylic acid was obtained. 0.005 parts by mass of HEMP as an initiator was added to the obtained mixed liquid and stirred until completely dissolved to prepare an aqueous solution (C3) which is a resin composition. Next, this aqueous solution (C3) was transferred to a petri dish having a diameter of 3 cm and a thickness of 1 cm, and UV light was irradiated from above the petri dish at an intensity of 3000 mJ/cm ² to try to prepare a crosslinked gel. However, the aqueous solution (C3) remained as an aqueous solution without cross-linking gelation. The evaluation results are shown in Table 2.

(Comparative Example 4)
An aqueous solution (C4) which was a resin composition from a mixed solution containing PVOH-6 in the same manner as in Comparative Example 1 except that the aqueous solution of polyacrylic acid was not contained and PVOH-2 was used instead of PVOH-1. Was produced. Then, a film (SC4) was obtained in the same manner as in Comparative Example 1 except that this aqueous solution (C4) was used and the intensity of the irradiated UV light was changed to 3000 mJ/cm ² . Table 2 shows the evaluation results of the obtained film (SC4).

(Comparative example 5)
An aqueous solution (C5) which is a resin composition was prepared from a mixed solution containing polyacrylic acid in the same manner as in Comparative Example 1 except that PVOH-6 was not included. Then, this aqueous solution (C5) was transferred to a petri dish having a diameter of 3 cm and a thickness of 1 cm, and UV light was irradiated from above the petri dish at an intensity of 3000 mJ/cm ² to try to prepare a crosslinked gel. However, the aqueous solution (C5) remained as an aqueous solution without being crosslinked. The evaluation results are shown in Table 2.

As shown in Table 2, each of the crosslinkable resin compositions (E1) to (E8) prepared in Examples 1 to 8 was converted into a crosslinked film or gel by irradiation with UV light or addition of a crosslinking agent. It could be molded. On the other hand, in the resin compositions (C1) to (C3) and (C5) of Comparative Examples 1 to 3 and 5 in which the modified polyvinyl alcohol-based polymer was not used, the crosslinking itself was difficult and the film was made water resistant. Or could not be gelled from an aqueous solution.

Further focusing on the films or gels (SE1) to (SE8), (SC1) to (SC3) and (SC5) obtained in Examples 1 to 8 and Comparative Examples 1 to 3 and 5, It can be seen that the obtained films or gels (SE1) to (SE8) obtained crosslinked products having good or excellent water resistance and water absorption. In contrast, in the films or gels (SC1) to (SC3) and (SC5) obtained in Comparative Examples 1 to 3 and 5, all (100%) were dissolved in the evaluation of water resistance and water absorption. However, it was not possible to obtain a crosslinked hydrate resistant material. Further, like the film (SC4) obtained in Comparative Example 4, the modified vinyl alcohol polymer alone has a high degree of cross-linking and water resistance, but has extremely low water absorption, and a cured product having water absorption cannot be obtained. It was

According to the present invention, as a material for forming various industrial products, as a resin molding field, a healthcare product field, a medical product field, an agricultural/horticultural field, a food/distribution field, a pet-related product field, an electrical field, and a construction field. It is useful in fields.

Claims (13)

1. A crosslinkable resin composition containing a modified vinyl alcohol polymer containing a vinyl alcohol unit and a structural unit represented by the following formula (I), and an anionic polyelectrolyte:
   

   

   (In the formula (I), X is a carbon-carbon bond or a divalent saturated hydrocarbon group having 1 to 10 carbon atoms which may be branched, and Y is a hydrogen atom or an optionally branched carbon atom. A divalent saturated hydrocarbon group of the numbers 1 to 6 and Z is a hydrogen atom or a methyl group).
2. The crosslinkable resin composition according to claim 1, wherein Y in the formula (I) is a hydrogen atom.
3. The crosslinkable resin composition according to claim 1 or 2, wherein X in the formula (I) is a carbon-carbon bond.
4. The crosslinkable resin composition according to any one of claims 1 to 3, wherein the modified vinyl alcohol polymer contains the structural unit represented by the formula (I) in a proportion of 0.01 to 3 mol%.
5. 5. The anionic polyelectrolyte is a polymer having a side chain having at least one group selected from the group consisting of a carboxylic acid group or a salt thereof and a sulfonic acid group or a salt thereof. The crosslinkable resin composition according to item 1.
6. The crosslinkable resin composition according to any one of claims 1 to 4, wherein the anionic polyelectrolyte is poly(meth)acrylic acid.
7. The crosslinkable resin composition according to any one of claims 1 to 6, which further contains a crosslinking agent.
8. A cured product containing a crosslinked product of the crosslinkable resin composition according to any one of claims 1 to 7.
9. The cured product according to claim 8, wherein the cured product has a water absorption ratio of 5 or more.
10. The cured product according to claim 8 or 9, wherein the elution rate of the cured product is 40% by mass or less.
11. A method for producing a cured product, which comprises a step of crosslinking the crosslinkable resin composition by irradiating the crosslinkable resin composition according to any one of claims 1 to 6 with an active energy ray.
12. A method for producing a cured product, which comprises a step of crosslinking the crosslinkable composition by heating the crosslinkable resin composition according to claim 7.
13. A water absorbent product containing the cured product according to claim 8.