JPH11323152A - Water-absorbent resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-absorbent resin compsn. which is excellent in capability not only for absorbing pure water but also for absorbing an aq. soln. contg. an acid, alkali, salt, or hydrophilic org. solvent by incorporating a thermoplastic resin, a crossllinked N-vinylcarboxamide polymer, a dispersant, and a compatibilizer into the same. SOLUTION: A thermoplastic resin pref. comprising at least one polymer selected from among (modified) polyolefins, polyamides, polyesters, styrene resins, and olefinic elastomers; a crosslinked N-vinylcarboxamide polymer which has N-vinylcarboxamide-derived repeating units represented by the formula as the main repeating units and is prepd. pref. from an N-vinylcarboxamide monomer or a monomer mixture contg. at least 50 wt.% N-vinylcarboxamide monomer and a crosslinker having at least two polymerizable unsatd. bond in the molecule; a dispersant; and a compatibilizer are incorporated. In the formula, R<1> and R<2> are each H or 1-3C alkyl.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-absorbent resin composition having good moldability. More specifically, not only pure water (including distilled water, deionized water, etc.) but also an aqueous solution containing an acid, an alkali or a salt, a water-containing organic solvent, and even a hydrophilic organic solvent have good water absorption or It has solvent absorbing performance, and has a higher molding processing temperature (about 20
The present invention relates to a water-absorbent resin composition which is stable even at 0 ° C to 300 ° C) and can be formed into various forms as various materials requiring water absorption and liquid absorption.

[0002]

2. Description of the Related Art At present, water-absorbent resins are used as absorbents for sanitary materials such as disposable diapers and sanitary products, water retention agents for agricultural and horticultural use, and other industrial materials such as starch-acrylic acid graft copolymer alkali metal salts. Starch such as starch-acrylonitrile graft copolymer saponified, starch-acrylamide graft copolymer saponified, carboxymethylcellulose, cellulose-acrylonitrile graft copolymer saponified, cellulose-acrylic acid graft copolymer alkali metal salt, etc. Cellulose, polyacrylic acid such as alkali metal polyacrylate, polyvinyl alcohol-acrylic acid graft copolymer alkali metal salt,
Various types of polyvinyl alcohols such as a polyvinyl alcohol-maleic anhydride graft copolymer have been used. These resins are cross-linked to obtain a water-absorbing ability and a shape-retaining property after water-absorption, and are in powder form. Further, in recent years, the use of the water-absorbing resin has been steadily expanding, and there is a great demand not only in the form of powder but also in the form of films, sheets, fibers and the like. However, since the current water-absorbing resin is a crosslinked product, it has no thermoplasticity, and processing into films, sheets, fibers, and the like has been extremely difficult. Therefore, water-absorbent resins that can be molded into films and fibers are being studied.For example, a method of blending a water-absorbent resin with a thermoplastic resin such as polyethylene, polypropylene, polyester, or styrene, which has excellent moldability, is known as thermoplastic resin. And the water-absorbing resin had poor compatibility, and a uniform dispersion could not be obtained.

[0003] Therefore, a blend with a polar group-containing thermoplastic resin, which is considered to have a higher affinity for a water-absorbing resin, has been studied, and a polar group-containing thermoplastic resin such as EVA, EEA, or EAA has poor dispersibility. It turned out to be good. However, the water-absorbent resin blend obtained by the above method has poor thermal stability at high temperatures due to the introduction of a polar group, and the mechanical properties, chemical resistance, etc. are considerably poorer than homopolymers. Had disadvantages. In addition, the above-mentioned water-absorbent resin has poor thermal stability at high temperatures,
In a long-term residence or molding at a high temperature such as 0 ° C. or more, thermal decomposition proceeds, and the water absorption is extremely reduced, so that there is a great restriction on the thermoplastic resin to be selected and the application of various molding methods. Was. Further, the water-absorbing resin has sufficient water-absorbing properties with respect to pure water containing no electrolytes or ions (regardless of suspended substances) and has swelling properties, but it has acid,
The water absorption of an electrolyte or an aqueous solution containing ions such as alkalis and various water-soluble salts or ions, or seawater was greatly reduced, and was not sufficiently satisfactory.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and has been developed in view of the fact that a conventional blend of a thermoplastic resin and a water-absorbent resin cannot sufficiently exhibit performance. Improvement of dispersibility of water-absorbent resin in homopolymer utilizing characteristics of polymer, improvement of thermal stability of water-absorbent resin for applying various thermoplastic resins and various molding methods, and conventional water-absorbent resin It is an object of the present invention to provide a thermoplastic water-absorbent resin composition which has been impossible and which has an excellent solution absorbability of an aqueous solution containing an acid, an alkali, various salts, an aqueous solution containing an organic solvent, or a hydrophilic organic solvent.

[0005]

Means for Solving the Problems The present inventors disperse an N-vinylcarboxylic acid amide-based polymer having high water-absorbing performance with respect to an aqueous solution containing an acid, an alkali or various salts and having good thermal stability at a high temperature. It has been found that the above object can be achieved by using an agent and a compatibilizer, and the present invention has been completed. That is, the present invention provides a water-absorbent resin composition having excellent water-absorbing performance, solvent-absorbing performance, and surface hydrophilicity, and capable of being subjected to various thermoforming.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to the following. 1) (1) a thermoplastic resin, (2) the following general formula (I) CH ₂ ＣＨCH—NR ¹ —COR ² (I) (wherein, R ¹ and R ² each independently represent a hydrogen atom or a carbon atom A crosslinked product of an N-vinylcarboxylic acid amide-based polymer having, as a main repeating unit, a repeating unit derived from N-vinylcarboxylic acid amide represented by (3), (3) a dispersant, and (4) A) water-absorbent resin composition comprising a compatibilizer.

2) The thermoplastic resin is a polyolefin,
The water-absorbent resin composition according to the above 1), which is at least one thermoplastic resin selected from the group consisting of a modified polyolefin, a polyamide, a polyester, a styrene-based resin and an olefin-based elastomer. 3) The crosslinked N-vinylcarboxylic acid amide polymer is
An N-vinylcarboxylic acid amide monomer represented by the above general formula (I) or a monomer mixture containing 50% by weight or more of the monomer and at least two polymerizable unsaturated bonds in one molecule; The water-absorbent resin composition according to the above 1) or 2), which is a crosslinked polymer derived from a crosslinking agent. 4) The crosslinking agent is 2 × 10 ⁻⁴ to 10 mol% of the total monomer
The water-absorbent resin composition according to the above item 3), wherein 5) The water-absorbent resin composition according to any one of 1) to 4) above, wherein the N-vinylcarboxylic acid amide is N-vinylacetamide. 6) (1) For 100 parts by weight of the thermoplastic resin, (2)
20 to 4 crosslinked N-vinylcarboxylic acid amide polymers
The water-absorbent resin composition according to any one of the above 1) to 5), comprising 00 parts by weight, (3) 0 to 50 parts by weight of a dispersant, and (4) 0 to 100 parts by weight of a compatibilizer.

[0008] The crosslinked N-vinylcarboxylic acid amide polymer used in the present invention is a monomer of the above-mentioned N-vinylcarboxylic acid amide (A) or, if necessary, a comonomer (B) copolymerizable therewith. Crosslinking agent (C)
And using a radical polymerization initiator under substantially oxygen-free conditions. Examples of N-vinylcarboxylic acid amide (A) include N-vinylacetamide, N-vinylformamide, N-methyl-N-vinylformamide, N-methyl-N-vinylacetamide,
N-ethyl-N-vinylacetamide and the like,
Among these, N-vinylacetamide is particularly preferred, and at least one of these is used.

The comonomer (B) copolymerizable with N-vinylcarboxylic acid amide includes (meth) acrylic acid (salt), (meth) acrylamido-2-methylpropanesulfonic acid (salt), vinylsulfonic acid ( Salts), (meth) acrylates of lower alkyl (C ₄ or less) substituted by dimethylamino group, (meth) acrylates of lower alkyl (C ₄ or less) substituted by hydroxyl group, acrylonitrile, etc. Among them, acrylic acid (salt), acrylamido-2-methylpropanesulfonic acid (salt) and vinylsulfonic acid (salt) are advantageous in terms of performance and cost. These salts include sodium salts, potassium salts, ammonium salts and the like, but other salts can also be used. One or more of these can be used.

The N-vinylcarboxylic acid amide of the above-mentioned polymer crosslinked product (including a copolymer crosslinked product; the same applies hereinafter) is usually the sum of the monomers comprising N-vinylcarboxylic acid amide and a comonomer (monomer 50% by weight or more, preferably 70% by weight or more of the mixture). For example, if the compounding ratio of N-vinyl carboxylic acid amide and sodium acrylate is 100: 0, the water absorption capacity of a 1.0% by weight CaCl ₂ aqueous solution changes depending on its own weight with the crosslinking density and the degree of polymerization. As a rule of thumb, it is about 50 times, and if this is 70:30, about 35 times.

The water absorption capacity is measured by, for example, introducing 2.0 g of a crosslinked polymer into a liquid (for example, 1.0 g by weight of an aqueous solution of CaCl ₂ ) of about 1 liter and absorbing water until saturation. It is a numerical value calculated by the following formula after filtering through a 200 mesh wire mesh. Water absorption ratio = [(weight of swollen polymer crosslinked product) / (weight of used polymer crosslinked product)]-1

[0012] The 1
Specific examples of the cross-linking agent (C) having at least two polymerizable unsaturated bonds in a molecule (hereinafter referred to as a cross-linkable compound) include N, N'-methylenebisacrylamide, triethylene glycol (meth) acrylate Having a plurality of (meth) acrylic groups such as pentaerythritol tri (meth) acrylate, N, N'-alkylenebis (N-vinylcarboxylic acid amide) such as N, N'-butylenebis (N-vinylacetamide) Compound, compound having two or more allyl groups such as diethylene glycol diallyl ether, trimethylolpropane triallyl ether, tetraallyloxyethane, pentaerythritol triallyl ether, diallyl adipate, diallyl terephthalate, divinyl oxalate, divinyl succinate, Divinyl malonate Divinyl adipate, divinyl maleate, trivinyl citrate, such as a compound having a vinyl ester structure such as pyromellitic acid tetra vinyl least two are mentioned, these can be used alone or in combination.

The amount of the crosslinking agent used is 2 × 10 ⁻⁴ to 2 × 10 ^{−4 based on} the total amount of the monomers in consideration of gel strength and water absorption.
10 mol% is preferred, and the range of 5 × 10 ⁻⁴ to 2 mol% is more preferred.

The polymerization initiator used in the production of the above-mentioned crosslinked polymer may be any of conventionally known peroxides, organic and inorganic peracids or salts thereof and azobis compounds, or various polymerization initiators thereof. Redox-based initiators in combination with a reducing agent are used, and among them, azobis-based initiators such as azobisisobutyronitrile and azobis (2-amidinopropane) dihydrochloride are particularly preferable. These polymerization initiators may be used in an amount generally used, and the amount used is not particularly limited. The polymerization initiation temperature is about -10 to 80 ° C, and the reaction time is usually 0.5 to
The time is about 30 hours, but it is not particularly limited as long as the desired polymer crosslinked product is obtained.

After the N-vinylcarboxylic acid amide (co) polymer is produced by the above-mentioned method, it is mixed with various epoxy compounds having two or more functional groups, alcohols, amines, isocyanates, divalent or higher metal ions and the like. It may be produced by post-crosslinking by reaction with a functional group derived from a comonomer. The copolymerization process is not necessarily limited, but an aqueous solution polymerization method, a reversed-phase suspension polymerization method, a reversed-phase emulsion polymerization method, and the like, which have been conventionally adopted as a method for producing a crosslinked product of sodium polyacrylate, can be used. Specific examples are disclosed in JP-A-3-223304 and JP-A-4-2302.
No. 50 and JP-A-4-346833 can be employed.

As the crosslinked N-vinylcarboxylic acid amide polymer used in the present invention, one or a mixture of two or more selected from the N-vinylcarboxylic acid amide polymers produced by the above-mentioned method can be used. Can be used. The particle size of the crosslinked N-vinylcarboxylic acid amide polymer used in the present invention is usually 500 μm or less, preferably 100 μm or less, particularly preferably 50 μm or less. If the particle size is larger than 500 μm, the dispersibility in the thermoplastic resin is poor, and when the aqueous liquid is swollen, the liquid absorbent excessively detaches from the thermoplastic resin, or large irregularities are present on the thermoplastic resin surface. It is not preferable because it can be done.

The thermoplastic resin used in the present invention includes:
There is no problem as long as the plastic softens when heated and exhibits plasticity, and solidifies when cooled. As the thermoplastic resin, polyolefin, modified polyolefin, styrene resin, polyvinyl chloride, general-purpose plastics such as methacrylic resin, polyamide, polyacetal, polycarbonate, modified polyphenylene ether, engineering plastics such as thermoplastic polyester, fluororesin, polyphenylene sulfide, Super engineering plastics such as liquid crystal polyester and olefin elastomers can be used. Among these, polyolefins, modified polyolefins, styrene-based resins, polyamides, thermoplastic polyesters, and olefin-based elastomers are particularly preferred in consideration of resin properties, moldability, product properties, and the like.

Examples of the polyolefin include polyethylene, polypropylene, polybutene, poly-4-methylpentene-1, ionomer, ethylene-propylene copolymer, ethylene-hexene copolymer, ethylene-vinyl acetate copolymer, ethylene- Examples thereof include vinyl alcohol copolymers and copolymers containing a small amount of diene. Examples of the modified polyolefin include carboxylic acid groups (acetic acid group, acrylic acid group, methacrylic acid group, fumaric acid group, itaconic acid group, etc.) and carboxylic acid metal bases (sodium salt, calcium salt, magnesium salt, zinc salt, etc.) At least one selected from carboxylic acid ester groups (methyl ester group, ethyl ester group, propyl ester group, butyl ester group, vinyl ester group, etc.), acid anhydride groups (maleic anhydride group, etc.), epoxy groups and oxazoline groups. It is a polyolefin having one type of functional group. Examples of the polyolefin as a raw material include the above-mentioned polyolefins.

Specific examples of such a modified polyolefin include ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / fumaric acid copolymer, ethylene / methacrylic acid / zinc methacrylate copolymer, Ethylene / acrylic acid / sodium methacrylate copolymer, ethylene / isobutyl acrylate / methacrylic acid /
Zinc methacrylate copolymer, ethylene / methyl methacrylate / methacrylic acid / magnesium methacrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene /
Vinyl acetate copolymer, ethylene / glycidyl methacrylate copolymer, ethylene / vinyl acetate / glycidyl methacrylate copolymer, maleic anhydride grafted polyethylene, acrylic acid grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene / Propylene copolymer, acrylic acid grafted ethylene / propylene copolymer, fumaric acid grafted ethylene /
1-butene copolymer, ethylene / 1-hexene-itaconic acid copolymer, ethylene / propylene-endobicyclo [2,2,1] -5-heptene-2,3-dicarboxylic anhydride copolymer, ethylene / Propylene-methacrylic acid grafted glycidyl copolymer, maleic anhydride grafted ethylene / propylene / 1,4-hexadiene copolymer,
Fumaric acid grafted ethylene / propylene / dicyclopentadiene copolymer, maleic acid grafted ethylene / propylene / norbornadiene copolymer, acrylic acid grafted ethylene / vinyl acetate copolymer, maleic anhydride grafted SEBS (styrene / ethylene / butylene / styrene) ) Copolymer and maleic anhydride grafted SEPS
(Styrene / ethylene / propylene / styrene) copolymers, and these modified polyolefins may be used alone or in combination of two or more.

The above-mentioned modified polyolefin can be produced by a known method, for example, JP-B-39-6810 and JP-B-46.
-27527, JP-B-50-2630, JP-B-52-43677, JP-B-53-5716, JP-B-53-19037, and JP-B-53-4
It can be produced according to the methods disclosed in, for example, Japanese Patent Publication No. 1173 and Japanese Patent Publication No. 56-9925. In addition, about the ethylene ionomer, generally "Surlyn",
Various products marketed under the trade names "Himilan" and "Corporen" can be used. The degree of polymerization of the modified polyolefin used in the present invention is not particularly limited, but usually has a melt index of 0.01 to 100 g /
Anything within the range of 10 minutes can be arbitrarily selected.

Examples of the styrene resin include styrene homopolymer, polystyrene such as impact-resistant polystyrene, styrene / acrylonitrile copolymer containing styrene as a main component, styrene / acrylonitrile / butadiene copolymer, and styrene / methyl methacrylate. Styrene-based copolymers such as copolymers can be exemplified. Various polyamides can be used. Specific examples thereof include polylactams such as polyamide 6, polyamide 11, and polyamide 12; and dicarboxylic acids such as polyamide 66, polyamide 610, polyamide 612, and polyamide 46, and diamines. Polyamides; Polyamide 6/6
6, polyamide 6/12, polyamide 6/66/610
Such as copolymer polyamides; polyamide 6 / 6T (T:
Terephthalic acid component), semi-aromatic polyamides obtained from an aromatic dicarboxylic acid such as isophthalic acid and meta-xylenediamine or aliphatic diamine; polyesteramide, polyetheramide and polyesteretheramide. The above various polyamides may be used alone or in combination of two or more.

The thermoplastic polyester is a polyester obtained by a polycondensation reaction between terephthalic acid or a dialkyl ester thereof and an aliphatic glycol, or a copolymer of the same with another different comonomer based on the polyester. Representative examples of such polyesters include polyethylene terephthalate and polybutylene terephthalate. Examples of the aliphatic glycols include ethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol and the like.

Further, the olefin-based elastomer has rubber elasticity at room temperature, exhibits plasticity similar to that of thermoplastic at high temperature, and is structurally composed of a soft segment exhibiting rubber elasticity and a hard segment exhibiting similar crosslinking. Therefore, it is required that when the liquid absorbing agent is blended, it can be easily dispersed and maintain its shape, and that it has sufficient strength. There is no limitation as long as such an olefin-based elastomer is used. Generally, the hard segment is polypropylene or polyethylene,
The soft segment is a rubber component such as an ethylene-propylene-diene rubber or an ethylene-propylene rubber or an amorphous polyethylene. Other olefin-based elastomers include those whose hard segment is made of polyethylene, whose soft segment is made of ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer or ethylene-glycidyl methacrylate copolymer, and whose hard segment is metal carboxylate. It is known that ion clusters and soft segments are made of amorphous polyethylene.

As for the production method, those produced directly by a polymerization method, those obtained by blending two or more rubber components and crystal components, and those obtained by blending are further subjected to partial crosslinking or dynamic crosslinking of the rubber components. What went is known. In the present invention, at least one of the above-mentioned olefin elastomers is used. By using such an olefin-based elastomer, not only can the vulcanization step be omitted, but also it is possible to produce with a conventional extruder. It has become possible to improve productivity, reduce manufacturing costs, and apply thermoplastic molding methods.
It has become possible to mold into a desired shape by a molding method such as extrusion molding. Further, as long as the effects of the present invention are not impaired, various elastomers, lubricants, plasticizers, stabilizers, antistatic agents and pigments, and other additives may be blended.

In the present invention, a crosslinked N-vinylcarboxylic acid amide polymer (hereinafter also referred to as "water-absorbing polymer").
In order to uniformly disperse the solid fine particles in the thermoplastic resin, a dispersant is used. When the difference between the cohesive energies is large, for example, when the thermoplastic resin is a polyolefin, it is difficult to uniformly disperse the water-absorbing polymer. In order to completely disperse the aggregate of the solid particles of the water-absorbing polymer in the polyolefin, it is preferable to coat the surface of the fine particles of the water-absorbing polymer with a dispersant,
The interfacial tension between the dispersant and the polyolefin must be greater than the cohesion between the particles. When the difference in cohesive energy between the two is small, such as polyamide, it is quite easy to uniformly disperse the water-absorbing polymer. Although it is preferable to use a dispersant, good dispersion may be obtained without using it. This is the same idea as the dispersion of the inorganic fine particles in the thermoplastic resin. In the case of (1), since the phenomenon of fusion between the fine particles occurs, it is required to completely coat the surface of the fine particles with the dispersant in order to prevent the phenomenon.

As the dispersant used in the present invention, a surfactant having both a hydrophilic part and a hydrophobic part in a molecule can be used. Further, as a characteristic required for the dispersant, the dispersant must be thermally stable at the temperature during melt kneading or molding (about 200 to 300 ° C.). Must be solid. Others are not particularly limited as long as they satisfy these conditions.

Specifically, cationic surfactants such as primary amine salts, tertiary amine salts, quaternary ammonium compounds and pyridine derivatives, sulfated oils, soaps, sulfated ester oils, sulfated amides Oils, olefin sulfates, aliphatic alcohol sulfates, alkyl sulfates, fatty acid ethyl sulfonates, alkyl sulfonates, alkyl naphthalene sulfonates, alkyl benzene sulfonates, succinate sulfonates,
Anionic surfactants such as phosphate ester salts, partial fatty acid esters of polyhydric alcohols, fatty alcohols, ethylene oxide adducts of fatty alcohols, fatty acids,
Fatty acid esters, fatty acid ethylene oxide adducts,
An ethylene oxide adduct of an aliphatic amine or an aliphatic amide, an ethylene oxide adduct of an alkyl phenol, an ethylene oxide adduct of an alkyl naphthol,
Examples include nonionic surfactants such as ethylene oxide adducts of partial fatty acid esters of polyhydric alcohols and oxides of polyethylene oligomers. These may be used alone or in combination of two or more as necessary.

The compatibilizer used in the present invention increases the adhesive strength between the thermoplastic resin and the solid fine particles of the water-absorbing polymer or the dispersant surrounding the fine particles, and improves the mechanical properties, water-absorbing properties, and other physical properties. Used to let. As the compatibilizer used in the present invention, a compound having a part compatible with the thermoplastic resin and a part compatible with the dispersant surrounding the solid fine particles of the water-absorbing polymer is preferable. It is preferably a compound having a carboxylic acid group, a carboxylic acid metal base, a carboxylic acid ester group, an acid anhydride group, an epoxy group, an amino group, or a hydroxyl group in a molecule, and is preferably (meth) acrylic acid, maleic acid, or fumaric acid. , Chloromaleic acid, cis-4-cyclohexene-1,2-dicarboxylic acid and their acid anhydrides, esters, half-alkyl esters, amides, imides and the like.
-Unsaturated dicarboxylic acids and their derivatives are preferred.
These functional groups may be used alone or in combination of two or more.

As a compatibilizer, a thermoplastic resin such as a modified polyolefin having the above functional group in the case of a polyolefin or an olefin elastomer, or a modified styrene resin or a modified styrene elastomer having the above functional group in the case of a styrene resin. In the case of polyester and polyamide, good dispersion can be achieved without using any compatibilizer.
Graft-modified thermoplastic polyesters, graft-modified polyamides, and the like as shown in JP-A-840-840 and Japanese Patent Application No. 8-295345 can also be used. In the case of the modified polyolefin, a good dispersion state can be obtained without using a compatibilizer.

The modified polyolefin used in the present invention may be the same as described above. Specific examples of the modified styrenic resin and elastomer include styrene / (meth) acrylic acid copolymer, styrene / maleic anhydride copolymer, styrene / methyl (meth) acrylate copolymer, and styrene / butadiene. / (Meth) acrylic acid copolymer, styrene / butadiene / maleic anhydride copolymer, styrene / isoprene / (meth) acrylic acid copolymer, styrene / isoprene / maleic anhydride copolymer, styrene /
Ethylene / butadiene / (meth) acrylic acid copolymer,
Examples include styrene / ethylene / butadiene / maleic anhydride copolymer, styrene / propylene / isoprene / (meth) acrylic acid copolymer, and styrene / propylene / isoprene / maleic anhydride copolymer.

The mixing ratio of each component in the water-absorbing resin composition of the present invention is as follows: (1) 100 parts by weight of the thermoplastic resin, and (2) 20 to 400 parts by weight of the crosslinked N-vinylcarboxylic acid amide polymer. Parts, preferably 50 to 200 parts by weight, (3) 0 to 50 parts by weight of the dispersant, preferably 2 to 35 parts by weight.
It is preferred to use 0 to 100 parts by weight, and preferably 2 to 50 parts by weight, of the compatibilizer and (4) the compatibilizer.

The water-absorbent resin composition of the present invention is produced by kneading a powder obtained by coating a solid fine particle of a liquid-absorbing agent with a dispersant, a compatibilizer and a thermoplastic resin in an ordinary thermoplastic resin extruder. be able to. In the case of an olefin-based elastomer, mixing is performed by a closed kneader such as a Banbury mixer or a kneader, or a rubber kneader such as an open roll. At the time of mixing, it can be produced by putting a thermoplastic resin, N-vinylcarboxylic acid amide-based polymer fine particles coated on the surface with a dispersant and a compatibilizer into a kneader or an extruder. At this time, usual rubber compounding such as reinforcing agents such as carbon black, inorganic fillers such as calcium carbonate, softeners such as process oils, plasticizers such as esters, antioxidants such as amines and phenols, etc. The compounding chemicals used can be added simultaneously.

With the water-absorbent resin composition of the present invention, various molded articles can be produced by various molding methods. As the molding method, a method applicable to a thermoplastic resin can be applied. For example, injection molding, extrusion molding, sheet molding, stamp molding and the like can be mentioned. This water-absorbent resin composition is formed into a shape suitable for a part to be used, and is disposed in a gap between structures such as a cable covering material or a tunnel or a building, and is used for water, seawater, and the like passing through the gap. It can be used for the purpose of expanding by contact with it, closing the gap and preventing water leakage. In addition, the water-absorbing resin composition of the present invention can be used not only as the above-mentioned water-stopping material and sealing material, but also as a water-retaining material or the like utilizing its water-absorbing performance. Furthermore, the water-absorbent resin composition of the present invention includes lower alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, lower carboxylic acids such as acetic acid, glycols such as ethylene glycol, propylene glycol, and diethylene glycol, and acetaldehyde. Aqueous solutions containing a water-soluble organic solvent such as aldehydes described above, and even the hydrophilic solvent itself, absorb and expand, so that it can be effectively used as the above-mentioned solvent-based anti-leakage agent, water-stopping material, and packing.

[0034]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. (Production Example 1) 200 g of N-vinylacetamide, 6 g of pentaerythritol triallyl ether, and 2000 g of deionized water were charged into a four-necked 3-L separable flask equipped with a nitrogen inlet tube, a thermometer, and an exhaust tube.
Per minute, nitrogen was introduced into the system for about 1 hour to degas. Thereafter, 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile) 3 dissolved in 100 ml of cyclohexane
g was added, the temperature in the system was raised to 30 ° C., and the mixture was stirred at 300 rpm for 6 hours. After allowing to cool, the contents were washed with acetone, and the solid content was vacuum dried at 60 ° C. for 6 hours. The obtained dry particles are pulverized and classified, and a homopolymer crosslinked product (NVA) having a particle size of 50 μm or less is obtained.
Polymer 1) was obtained.

Production Example 2 200 g of N-vinylacetamide and 20 g of acrylic acid were placed in a 3 liter glass reaction vessel.
g, 2000 ml of deionized water. This is N,
1.0 g of N'-diacetyl-N, N'-divinyl-1,3-bisaminomethylcyclohexane and 0.4 g of N, N'-methylenebisacrylamide were added, and the system was sufficiently degassed with nitrogen gas. Thereafter, the temperature was raised to 30 ° C. Next, 1 g of 2,2′-azobis (2-amidinopropane) dihydrochloride dissolved in 10 ml of water was added and reacted for 20 hours. After neutralizing the reaction product with sodium hydroxide, the product was taken out, subdivided with a minced meat machine, and dried in vacuum at 60 ° C. for 6 hours. The obtained dried particles are pulverized and classified to 50 μm.
m or less (NVA-based polymer 2).

The test method is described below. (1) Mechanical properties For olefin-based elastomers, see JIS K63.
01, tensile strength, elongation and hardness were measured, and for other thermoplastic resins, tensile strength and elongation were measured according to JIS K7113. (2) Swelling magnification Length 20 mm, width 20 mm, thickness 2 m sampled from a flat plate
The test piece of m was immersed in each aqueous solution at 23 ° C., and its volume was measured at predetermined intervals, and calculated by the following equation. Swelling magnification (times) = volume after swelling / volume before swelling (3) Swelling pressure Length 25 mm, width 25 mm, thickness 5 m collected from a flat plate
m was inserted between the two stainless steel plates, and adjusted so that there was no gap between the stainless steel plates and the flat plates. Then, the test pieces were immersed in various aqueous solutions at 23 ° C. to reduce the expansion pressure generated over time. Reading was performed via a load cell provided on the upper part of the stainless steel plate.

Examples 1 to 20 Comparative Examples 1 and 2 N-vinylcarboxylic acid amide-based polymer fine particles and a dispersant were added to a Henschel mixer at the mixing ratios shown in Tables 1 and 2, and mixed at 100 ° C. for 15 minutes. The resulting mixture was vented into a co-rotating twin screw extruder (30 mm inner diameter, L
/ D = 42) to produce pellets. Further, flat plates (120 × 120 × 2 mm) were molded at a temperature (shown in Table 1) suitable for various thermoplastic resins by using an injection molding machine to obtain various test pieces. The mechanical strength and the swelling ratio of each test piece were measured, and the swelling pressure and hardness of the olefin elastomer were measured.
The results are shown in Tables 3 and 4.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

[0041]

[Table 4]

As is clear from Tables 3 and 4, Examples 1 to 20 have larger swelling ratios in saline solutions such as artificial seawater than Comparative Examples 1 and 2, and water absorption (stop) in these aqueous solutions is large. Water) indicates that the performance is excellent.

The resins used are shown below. LDPE (Low Density Polyethylene): JLEXX XF111-8 Nippon Polyolefin Co., Ltd. EVA (Ethylene-vinyl acetate copolymer): JLEXX EVA VH450W Nippon Polyolefin Co., Ltd. PP (Polypropylene): JALOMAR MA210 Nippon Polyolefin Co., Ltd. Modified polyolefin : Adtex ET184M Polyamide 6 manufactured by Nippon Polyolefin Co., Ltd.: Systemmer FE24001 PET (polyethylene terephthalate) manufactured by Showa Denko KK: Intrinsic viscosity 0.7 ABS manufactured by Soka Science Co., Ltd.: Stylac 301 Olefinic thermoplastic manufactured by Asahi Kasei Kogyo Co., Ltd. Elastomer: OREFLEX P201CN OREFLEX P132GN Nippon Polyolefin Co., Ltd. (Compatibilizer) Adtex ER901 , ER511F, ET184M: Nippon Polyolefin Co., Ltd. KRATON G FG1901X: Shell Japan Co., Ltd. Bondfast 2C: Sumitomo Chemical Co., Ltd. (dispersant) Stearic acid reagent: Junsei Chemical Co., Ltd. Limacale S-100: Riken Vitamin Co., Ltd. Acrylic polymer: Aquaric CS7S (crosslinked sodium polyacrylate) manufactured by Nippon Shokubai Co., Ltd.

In the thermal stability test, the weight loss starting temperature of the NVA-based polymers 1 and 2 and the acrylic water-absorbing polymer was measured at a heating rate of 10 ° C./min. Under a stream of nitrogen and air, a sample volume of approximately 10 mg was performed. Weight loss start temperature (° C.) Nitrogen air NVA polymer 1 350 330 NVA polymer 2 320 305 Crosslinked sodium polyacrylate 250 210 Thus, the N-vinylcarboxylic acid amide-based polymer has good thermal stability. Since a heat stabilizer (antioxidant or the like) is not added to the measurement sample, the stability can be further increased by several tens of degrees Celsius by adding the stabilizer.

[0045]

The water-absorbent resin composition of the present invention can be used not only for ordinary water but also for aqueous solutions containing electrolytes such as acids, alkalis and various salts and ions, and aqueous solutions containing hydrophilic organic solvents and the like. It has good water absorption or solvent absorption performance even for organic solvents, and has a high molding processing temperature (about 20
(0 ° C to 300 ° C), which are stable and require water absorption and liquid absorption, such as piping and other equipment, such as submarine tunnels, buildings,
Shield segment joint surface that is extremely difficult to replace when water leakage or cracks occur, such as buried objects, joints such as fume pipes, joints of concrete structures,
It can be used as a space filling material or packing material such as a pipe joint for factory drainage, as a material for various packaging, civil engineering construction, agricultural and horticultural use, medical care, clothing, daily necessities and the like. In addition, since the water-absorbent resin composition of the present invention can be applied to a normal molding method of a thermoplastic resin (eg, injection molding, extrusion molding, sheet molding, stamp molding, etc.), the final product can be molded into an arbitrary shape. It is. Furthermore, since an extruder used for producing a thermoplastic resin can be used for producing a water-absorbent resin composition, productivity is greatly improved.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09K 3/10 C09K 3/10 Z 3/12 3/12

Claims (6)

[Claims] (1) a thermoplastic resin; (2) the following general formula (I): CH ₂ ＣＨCH—NR ¹ —COR ² (I) (wherein R ¹ and R ² are each independently a hydrogen atom or A N-vinylcarboxylic acid amide-based polymer crosslinked product having, as a main repeating unit, a repeating unit derived from an N-vinylcarboxylic acid amide represented by an alkyl group having 1 to 3 carbon atoms), (3) a dispersant, and (4) A water-absorbent resin composition containing a compatibilizer. 2. The thermoplastic resin according to claim 1, wherein the thermoplastic resin is at least one thermoplastic resin selected from the group consisting of polyolefins, modified polyolefins, polyamides, polyesters, styrene resins and olefin elastomers. The water-absorbent resin composition according to item 1. 3. A crosslinked product of an N-vinylcarboxylic acid amide-based polymer, wherein the N-vinylcarboxylic acid amide monomer represented by the general formula (I) or a monomer containing 50% by weight or more of the monomer. The water-absorbent resin composition according to claim 1 or 2, which is a crosslinked polymer derived from a monomer mixture and a crosslinking agent having at least two polymerizable unsaturated bonds in one molecule. 4. The crosslinking agent is used in an amount of 2 × 10 ^-4 to 1 of the total monomer.
The water-absorbent resin composition according to claim 3, which is 0 mol%. 5. The water-absorbent resin composition according to claim 1, wherein the N-vinylcarboxylic acid amide is N-vinylacetamide. 6. (1) 20 to 400 parts by weight of a crosslinked N-vinylcarboxylic acid amide polymer, (3) 0 to 50 parts by weight of a dispersant, based on 100 parts by weight of a thermoplastic resin. (4) The water-absorbent resin composition according to any one of claims 1 to 5, which contains the compatibilizer in a ratio of 0 to 100 parts by weight.