JP2000313723A - Oriented body of water-absorbing resin and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject oriented body useful for a film, a sheet or the like for wrapping, civil engineering and construction, etc., by drawing a water- absorbing resin composition comprising a thermoplastic resin and a specific N-vinylcarboxylic acid amide-based polymer. SOLUTION: This oriented body is obtained by orienting a water-absorbing resin composition comprising (A) a thermoplastic resin (e.g. a polyolefin) and (B) a cross-linked product of an N-vinylcarboxylic acid amide-based polymer having repeating units consisting essentially of repeating units derived from an N-vinylcarboxylic acid amide monomer of the formula CH2=CH-NR1-COR2 (R1 and R2 are each H or a 1-3C alkyl), preferably in an orientation ratio of >=2 times. The compounding proportion of the component B in the composition is preferably 5-400 pts.wt. based on 100 pts.wt. component A. In addition, the composition can contain (C) a disperser and (D) a compatibilizer, and the contents of the components C and D are preferably 0.1-50 pts.wt. and 0.1-100 pts.wt. respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stretched water-absorbent resin composition obtained by stretching at a specific magnification and a method for producing the same. More specifically, good water absorption not only for pure water (including distilled water, deionized water, etc.) but also for aqueous solutions containing acids, alkalis or salts, aqueous organic solvents, and hydrophilic organic solvents. Or it has a solvent absorption performance, and is stable even at a high molding processing temperature (about 180 to 300 ° C),
Retention of water-absorbent resin after water absorption, which is suitable for use as a material for various packaging, civil engineering, agricultural, horticultural, medical, clothing, daily goods etc. that require water absorption and liquid absorption TECHNICAL FIELD The present invention relates to a stretched body of a water-absorbent resin composition, which has excellent water-absorbing properties, has high water absorbability, and further suppresses dimensional change in the direction during water absorption by stretching, and a method for producing the stretched body.

[0002]

2. Description of the Related Art At present, water-absorbing resins are used as absorbents for sanitary materials such as disposable diapers and sanitary products, water retention agents for agriculture and horticulture, and other industrial materials such as starch / acrylic acid graft polymer alkali metal salts, starch / Acrylonitrile graft polymer saponified product, starch type such as starch / acrylamide graft polymer saponified product, carboxymethyl cellulose, cellulose / acrylonitrile grafted polymer saponified product, cellulose type such as cellulose / acrylic acid graft polymer alkali metal salt, polyacrylic Various types such as polyacrylic acids such as acid alkali metal salts, polyvinyl alcohol / acrylic acid graft polymer alkali metal salts, and polyvinyl alcohol types such as polyvinyl alcohol / maleic anhydride graft polymer are used. These resins are in the form of a crosslinked product in order to obtain a water-absorbing ability and a shape-retaining property after water-absorption, and are in powder form. Furthermore, in recent years, the use of the water-absorbent resin has been steadily expanding, and there is a strong demand for the water-absorbent resin not only in the form of powder but also in the form of a film, sheet, fiber or the like. However, the current water-absorbent resin is a crosslinked product and therefore has no thermoplasticity, and is extremely difficult to process into films, sheets, fibers, and the like. In addition, water-absorbent resins that can be formed into films and fibers have been studied, but they have not always been satisfactory. For example, a method of blending a water-absorbing resin with a thermoplastic resin such as polyethylene, polypropylene, polyester, and styrene, which has excellent moldability, has a poor compatibility between the thermoplastic resin and the water-absorbing resin, and cannot provide a uniform dispersion. Was. Therefore, a blend with a polar group-containing thermoplastic resin, which is considered to be more excellent in affinity with the water-absorbent resin, has been studied, and a polar group-containing thermoplastic resin such as EVA, EEA, or EAA has good dispersibility. It became clear. However, by introducing a polar group, the water-absorbent resin blend obtained by the method described above has poor thermal stability at high temperatures, and is considerably poor in mechanical properties, chemical resistance, etc. as compared with a homopolymer. Had disadvantages. Further, the above-mentioned water-absorbent resin has poor thermal stability at high temperatures, and in long-term residence or molding at a high temperature such as 200 ° C. or more, thermal decomposition progresses and water absorbency is extremely reduced. The resin and the application of various molding methods are greatly restricted. Furthermore, the above-mentioned water-absorbent resin has sufficient water-absorbency and expandability with respect to pure water (regardless of suspended substances) which does not contain electrolytes or ions, but has acid, alkali, various water-soluble salts, etc. However, the water absorption of an electrolyte or an ion-containing aqueous solution or seawater was greatly reduced, and was not sufficiently satisfactory. On the other hand, Japanese Patent Publication No. 61-37095 proposes a method of dramatically increasing the water absorption rate by foaming a water-absorbing resin composition. I was not able to fully demonstrate my ability.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made to a thermoplastic resin in which a conventional blend of a thermoplastic resin and a water-absorbent resin could not exhibit sufficient performance. Improvement of the dispersibility of the water-absorbent resin, improvement of the thermal stability of the water-absorbent resin for applying various thermoplastic resins and various molding methods, and acid and alkali which were impossible with the conventional water-absorbent resin. , An aqueous solution containing various salts or an aqueous solution containing an organic solvent or a hydrophilic organic solvent, has improved liquid absorbing properties, and has excellent retention of the water absorbing resin after absorbing water, and a dimensional change upon absorption of water is suppressed. An object of the present invention is to provide a stretched composition and a method for producing the same.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have developed a dispersing agent for an N-vinylcarboxylic acid amide-based polymer having good water absorption performance for an aqueous solution containing an acid, an alkali or various salts and good heat stability at a high temperature. By using a compatibilizer and dispersing it uniformly in various thermoplastic resins, and then molding and stretching the composition, it has excellent water absorption and solvent absorption properties, suppresses dimensional changes during water absorption, and retains its shape. It has been found that a stretched body of the water-absorbent resin composition having excellent properties can be obtained, and the present invention has been completed.

That is, the present invention relates to the following items. [1] (1) a thermoplastic resin and (2) the following general formula (I) CH ₂ ＣＨCH—NR ¹ —COR ² (I) (wherein R ¹ and R ² independently represent a hydrogen atom or a carbon atom ~
3 represents an alkyl group. )) Wherein a water-absorbent resin composition comprising a crosslinked N-vinylcarboxylic acid amide polymer having a repeating unit derived from an N-vinylcarboxylic acid amide monomer represented by the following formula as a main repeating unit is stretched. Stretched body of the water-absorbent resin composition. [2] (1) With respect to 100 parts by weight of the thermoplastic resin, (2)
5 to 40 crosslinked N-vinylcarboxylic acid amide polymer
The stretched body of the water-absorbent resin composition according to the above [1], which contains 0 parts by weight. [3] The above-mentioned [1] or [2], wherein a water-absorbent resin composition obtained by further adding (3) a dispersant and / or (4) a compatibilizer to the composition is stretched. The stretched body of the water-absorbent resin composition according to the above. [4] (1) 100 parts by weight of thermoplastic resin, (2)
5 to 40 crosslinked N-vinylcarboxylic acid amide polymer
The water-absorbent resin composition according to the above [3], which contains 0 parts by weight, (3) 0.1 to 50 parts by weight of a dispersant and / or (4) 0.1 to 100 parts by weight of a compatibilizer. Stretched body. [5] Any of the above [1] to [4], 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. A stretched body of the water-absorbent resin composition according to any one of the above. [6] N-vinyl carboxylic acid amide polymer crosslinked product,
An N-vinylcarboxylic acid amide monomer represented by the general formula (I) or a monomer mixture containing the monomer in an amount of 50% by weight or more, and having at least two polymerizable unsaturated bonds in one molecule; The stretched water-absorbent resin composition according to any one of the above [1] to [5], which is a crosslinked polymer derived from a crosslinking agent. [7] The crosslinking agent is 2 × 10 ⁻⁴ to 10 mol% of the total monomer
The stretched product of the water-absorbent resin composition according to the above [6]. [8] The stretched water-absorbent resin composition according to any one of the above [1] to [7], wherein the N-vinylcarboxylic acid amide is N-vinylacetamide. [9] The water-absorbent resin composition according to any one of [1] to [8] is melt-kneaded at a temperature equal to or higher than the melting point or glass transition point of the thermoplastic resin to form a mixture, and the mixture is molded and stretched. A method for producing a stretched body of a water-absorbent resin composition, comprising: [10] The method for producing a stretched water-absorbent resin composition according to the above [9], wherein uniaxial stretching or biaxial stretching is performed in the stretching. [11] The method for producing a stretched water-absorbent resin composition according to the above [9] or [10], wherein the stretch is performed at a stretch ratio of 2 or more.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The cross-linked N-vinylcarboxylic acid amide polymer used in the present invention may be a copolymer of the above-mentioned N-vinylcarboxylic acid amide (A) or, if necessary, a co-monomer (A). It can be produced by adding a crosslinking agent (C) to the mixture of the monomers of B) and using a radical polymerization initiator under substantially oxygen-free conditions. N
-Vinyl carboxylic acid amide (A) includes N-vinyl acetamide, N-vinyl formamide, N-methyl-
N-vinylformamide, N-methyl-N-vinylacetamide, N-ethyl-N-vinylacetamide and the like, among which N-vinylacetamide is particularly preferred from the viewpoint of water absorption or solvent absorption, stability and the like. preferable. At least one of these is used.

The comonomer (B) having a copolymerizability with N-vinylcarboxylic acid amide includes (meth) acrylic acid (salt), (meth) acrylamido-2-methylpropanesulfonic acid (salt), vinylsulfonic acid ( Salt), allylsulfonic acid (salt), (meth) acrylate of lower alkyl (C4 or less) substituted by dimethylamino group, lower alkyl (C
4) or less, (meth) acrylic acid ester, acrylonitrile, etc. Among them, acrylic acid (salt) and acrylamide-2-acid are advantageous in terms of performance and cost.
Methylpropanesulfonic acid (salt), vinylsulfonic acid (salt), allylsulfonic acid (salt) and acrylonitrile. 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.

A specific example of a crosslinking agent (C) having at least two polymerizable unsaturated bonds in one molecule (hereinafter, also referred to as a “crosslinkable compound”) used in the production of the above polymer crosslinked product. Is N, N'-methylenebisacrylamide,
Compounds having a plurality of (meth) acryl groups, such as ethylene glycol di (meth) acrylate and pentaerythritol tri (meth) acrylate; N, N'-alkylenebis (N, such as N, N'-butylenebis (N-vinylacetamide) -Vinylcarboxylic acid amide) compounds, compounds having two or more allyl groups such as diethylene glycol diallyl ether, trimethylolpropane triallyl ether, tetraallyloxyethane, pentaerythritol triallyl ether, diallyl adipate, diallyl terephthalate, oxalic acid Compounds having two or more vinyl ester structures, such as divinyl, divinyl succinate, divinyl malonate, divinyl adipate, divinyl maleate, trivinyl citrate, and tetravinyl pyromellitate, and the like. These may be used two or more with one or need.

The amount of these cross-linking agents to be used is 2 × 10 ⁻⁴ or more based on the total amount of 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.

[0010] The polymerization initiator used in the production of the above-mentioned polymer crosslinked product may be a peroxide, an organic or inorganic peracid or a salt thereof and an azobis-based compound, 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) hydrochloride are particularly preferable.

The amount of the polymerization initiator used is not particularly limited, and any commonly used amount may be used. The polymerization initiation temperature is about −10 to 80 ° C., and the reaction time is usually about 0.5 to 30 hours. However, the reaction time is not particularly limited as long as the desired crosslinked polymer can be obtained.

After the N-vinyl carboxylic acid amide copolymer is produced by the above-described method, various epoxy compounds having two or more functional groups, alcohols, amines, isocyanates, divalent or higher metal ions, and the like are converted into comonomers. It may be produced by post-crosslinking by reaction with a functional group derived therefrom. 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-4-23025.
0 and JP-A-4-346833 can be employed.

The crosslinked N-vinylcarboxylic acid amide polymer used in the present invention may be one or a mixture of two or more of the N-vinylcarboxylic acid amide polymers produced by the above method. 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. Tend to be able to.

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.

The polyolefins include polyethylene, polypropylene, polybutene, poly-4-methylpentene-1, ionomer, ethylene / propylene copolymer, ethylene / hexene copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl Alcohol copolymers, and copolymers containing a small amount of a diene therein, and the like can be given.

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). Carboxylic acid ester group (methyl ester group, ethyl ester group, propyl ester group, butyl ester group, vinyl ester group, etc.), acid anhydride group (maleic anhydride group, etc.), epoxy group and oxazoline group. And a polyolefin having at least one 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 / acrylic acid / maleic anhydride 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 Acid 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 Acid grafted ethylene / propylene / dicyclopentadiene copolymer, maleic acid grafted ethylene / propylene / norbornadiene copolymer, acrylic acid grafted ethylene / vinyl acetate copolymer, maleic anhydride grafted S
EBS (styrene / ethylene / butylene / styrene) copolymer and maleic anhydride-grafted SEPS (styrene / ethylene / propylene / styrene) copolymer. These modified polyolefins may be used alone or in combination of two or more. Is also good.

The above-mentioned modified polyolefin can be produced by a known method, for example, Japanese Patent Publication No. 39-6810 and Japanese Patent Publication No. 46-46.
-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 grades 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.
Those within the range of g / 10 minutes can be arbitrarily selected. As the styrene resin, styrene homopolymer,
Polystyrene such as impact-resistant polystyrene, styrene / acrylonitrile copolymer containing styrene as a main component,
Styrene-based copolymers such as styrene / acrylonitrile / butadiene copolymer and styrene / methyl methacrylate copolymer can be exemplified.

Various polyamides can be used, and specific examples thereof include polylactams such as polyamide 6, polyamide 11, and polyamide 12; polyamide 66, polyamide 610, polyamide 612, and the like.
Polyamides obtained from dicarboxylic acids such as polyamide 46 and diamines; polyamide 6/66, polyamide 6
/ 12, copolymer polyamides such as polyamide 6/66/610; polyamide 6 / 6T (T: terephthalic acid component), a half obtained from an aromatic dicarboxylic acid such as isophthalic acid and metaxylenediamine or aliphatic diamine. Aromatic polyamides; polyesteramides, polyetheramides and polyesteretheramides. The above-mentioned various polyamides may be used alone or in combination of two or more.

The thermoplastic polyester is a polyester obtained by a polycondensation reaction of terephthalic acid or a dialkyl ester thereof with an aliphatic glycol, or a copolymer of the same with another different comonomer containing the polyester as a main component. 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 is composed of a soft segment exhibiting rubber elasticity at room temperature, exhibiting plasticity similar to that of a thermoplastic plastic at a high temperature, and having a similar structure to 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 ethylene / propylene / diene rubber or ethylene / propylene rubber or 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 the 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. By using such an olefin-based elastomer, not only can the vulcanization step be omitted,
Because it is possible to manufacture with a conventional extruder, the conventional rubber composition requires a vulcanization step, which has been an obstacle to improving productivity, reducing manufacturing costs, and further improving the thermoplastic resin A molding method can be applied, and a desired shape can be formed by a molding method such as injection molding or 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 product of an 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 can be 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. Must be greater than the cohesion. 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 a concept equivalent to the dispersion of inorganic fine particles in a thermoplastic resin, but in the case of fine particles of a water-absorbing polymer, there is a further problem of the glass transition temperature of the polymer, and the temperature during melt-kneading is higher than the glass transition temperature. 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 required property for the dispersant, it must be thermally stable at the temperature during melt kneading or molding (about 180 to 300 ° C.), and at room temperature in order to prevent mutual adhesion of the water absorbent polymer fine particles coated with the dispersant. Must be solid. What is necessary is just to satisfy these conditions, and others are not particularly limited.

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, and one or more of these may be used as necessary.

In the present invention, a compatibilizer can be used. Such a compatibilizer increases the adhesive strength between the solid particles of the water-absorbing polymer or the dispersant surrounding the fine particles and the thermoplastic resin, and improves the mechanical properties, It is used to improve water absorption properties and other physical properties. As the compatibilizer used in the present invention, a compound having a site compatible with the thermoplastic resin and a site compatible with the dispersant surrounding the solid fine particles of the water-absorbing polymer is considered to be suitable. . 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 derivatives thereof are preferred. These functional groups may be used alone or in combination of two or more.

As the compatibilizer, thermoplastic polyesters such as modified polyolefins having the above functional groups in the case of polyolefins and modified styrene resins and modified styrene elastomers having the above functional groups in the case of styrene resins. In the case of polyamide, it is possible to achieve good dispersion without using a compatibilizer in particular. However, grafts such as those disclosed in JP-A-10-53631 and JP-A-10-139636 can be obtained. Modified thermoplastic polyester, graft-modified polyamide and the like 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-absorbent resin composition of the present invention is as follows: (1) 100 parts by weight of the thermoplastic resin, and (2) 5 to 400 parts by weight of the crosslinked N-vinylcarboxylic acid amide polymer. Parts, preferably 10 to 200 parts by weight. Furthermore, when (3) a dispersant and (4) a compatibilizer are used, (3) 0.1 to 50 parts by weight of the dispersant,
It is preferable to use 2 to 35 parts by weight, and / or 0.1 to 100 parts by weight, and preferably 2 to 50 parts by weight of the compatibilizer (4).

The water-absorbent resin composition according to the present invention comprises powder obtained by coating solid fine particles of a liquid absorbing agent with a dispersant before molding.
It can be produced by kneading a compatibilizer and a thermoplastic resin with a usual thermoplastic resin extruder. 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. When mixing
It can be manufactured by charging a kneader or an extruder with N-vinylcarboxylic acid amide-based polymer fine particles having a surface coated with a thermoplastic resin and a dispersant, and a compatibilizer. At this time, ordinary rubber compounds such as reinforcing agents such as carbon black, inorganic fillers such as calcium carbonate, softeners such as process oils, plasticizers such as esters, and antioxidants such as amines and phenols are used. The compounding chemicals used can be added simultaneously.

The water-absorbent resin composition of the present invention can be used to form various molded articles by various molding methods.
Conventional methods for thermoplastic resins, for example, T-die molding, inflation molding, calender molding, filament molding, press molding, injection molding, etc., and the composition is in the form of a film, sheet, etc. Objects, thread-like objects such as ribbons and fibers, plate-like objects, injection molded products, and the like.

In the present invention, the water-absorbent resin composition is molded and stretched by various molding methods applicable to thermoplastic resins. The stretching operation in the present invention may be performed either simultaneously with the molding or separately performed after the molding. For the stretching method, a conventional method for a thermoplastic resin is used, using a roll or the like depending on the application,
Various stretching methods such as short section stretching, rolling stretching, and stretching operation using a manual stretching machine can be selected.

Depending on the intended use, uniaxial stretching or biaxial stretching is performed. In particular, in the function of blocking the passage of liquid through gaps between structures such as a water-stopping material and a sealing material, a change in shape in the thickness direction is not affected. When it is acceptable but required that the change in shape in the planar direction is minimal, biaxial stretching is preferred. The stretching temperature is not particularly limited, but in the case of roll stretching, it is necessary to select a temperature at which the molded product does not adhere to the roll. Further, the stretching ratio is preferably 2 times or more. In order for the stretched body to have both water absorption and dimensional stability upon water absorption, the stretching ratio is preferably 3 to 12 times. If the stretching ratio is less than 2 times, the effect of stretching is not so much recognized, and the change in volume at the time of water absorption is large despite the low water absorption ratio, which is not preferable.

The stretched product of the water-absorbent resin composition of the present invention is formed into a shape suitable for a portion to be used, and is usually disposed in a gap between structures such as a cable covering material and a tunnel or a building, and passes through the gap. When it comes into contact with incoming water, seawater, or the like, it expands and closes the gap, thereby preventing water leakage.
In addition, the stretched water-absorbent resin composition of the present invention can be used not only as the water-stopping material and the sealing material described above, but also as a water-retaining material, a water-absorbing material, and the like utilizing the water-absorbing performance. In that case, as a single film or sheet, preferably as a laminated film or sheet with other materials, or woven, etc., building materials for food packaging, chemical packaging, agricultural and horticultural use, condensation prevention, interior decoration, etc. It can be applied to the fields of garments, sanitary goods, oil / water separation, antistatic, clothing, shoes and other accessories. Further, the stretched water-absorbent resin composition of the present invention is methanol, lower alcohols such as ethanol, acetone, lower ketones such as methyl ethyl ketone, lower carboxylic acids such as acetic acid, ethylene glycol, propylene glycol, glycols such as diethylene glycol, An aqueous solution containing a water-soluble organic solvent such as aldehydes such as acetaldehyde, and even the hydrophilic solvent itself, absorbs and expands.However, the dimensional change in the stretching direction is suppressed by stretching. It can be effectively used in applications where dimensional changes are unacceptable, for example, as a liquid-absorbing material, water-blocking material, packing, and water-blocking sheet.

[0035]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The test method is described below. (1) Water absorption ratio 23 ° C. using a test piece of a fixed shape collected from each stretched body
Immersed in each solution of the above, the weight was measured after 24 hours,
It was calculated by the following equation. Water absorption (%) = {[(weight of water-absorbent resin composition after water absorption) / (weight of water-absorbent resin composition before water absorption)] − 1} ×
100 (2) Dimensional change rate Using a stretched body of a fixed shape, immersed in each solution at 23 ° C,
The length in the stretching direction after 24 hours was measured and calculated by the following equation. Dimensional change rate (%) = ｛[(length of stretched sheet that absorbed water)
/ (Initial length of stretched sheet)]-1｝ × 100

Examples 1 to 5 Comparative Examples 1 and 2 NA-010 fine particles and a dispersant were charged into a Henschel mixer at the compounding ratios shown in Table 1, and mixed at 100 ° C. for 15 minutes. Twin-screw extruder with venting agent and thermoplastic resin (30 mm inner diameter, L / D =
The mixture was melt-kneaded in 42) to produce pellets. The obtained pellets were molded at a temperature suitable for various thermoplastic resins shown in Table 1, and stretched at room temperature using a manual stretching machine to obtain a biaxially stretched sheet.

Example 6 Under the molding conditions shown in Table 1, using a coaxial twin screw extruder (screw diameter 40 mm, L / D = 26) manufactured by Yoshii Iron and Steel Co., Ltd. After water cooling at a temperature of 20 ° C., a thread-like molded body was obtained using a take-off roll,
It was drawn by a manual type uniaxial drawing machine to obtain a uniaxially drawn yarn.

Example 7 Under the molding conditions shown in Table 1, using a coaxial twin screw extruder (screw diameter: 40 mm, L / D = 32) manufactured by Tanabe Plastics Co., Ltd., using a coat hanger type 400 mm T die and a cooling roll R _{1: 25 ℃, R 2:} 25 ℃, R 3: 2
A three-roll type take-up machine having a roll diameter of 100 mmφ was attached at 0 ° C. to obtain a sheet at a take-up speed of 1.5 m / min, and in a direction perpendicular to the take-up direction, a manual uniaxial stretching machine was used to obtain a biaxially stretched sheet.

Next, the water absorption ratio and the dimensional change of the stretched product thus obtained were measured. Table 1 shows the results.

[0041]

[Table 1]

As is clear from Table 1, Examples 1 to 7
Shows a stable water absorption ratio irrespective of the solution as compared with the comparative example, and the dimensional change after water absorption is small. The stretched water-absorbent resin composition of the present invention shows that the solution (distilled water, artificial seawater, alcohol) is extremely excellent in water absorption (water stoppage) performance and step stability. Further, it is effective when the target solution is not specified or when there are a plurality of target solutions.

The resins and the like used are shown below. EVA (ethylene-vinyl acetate copolymer): JELEX EVA FL14-1 Nippon Polyolefin Co., Ltd. EEA (ethylene / acrylic acid copolymer): Lexpearl A4200 Nippon Polyolefin Co., Ltd. EMAMAH (ethylene / acrylic acid / maleic anhydride) Copolymer): Lexpearl ET184M Nippon Polyolefin Co., Ltd. CPE (chlorinated polyethylene): Eraslen 351MA Showa Denko KK TPO (Olefin thermoplastic elastomer): Oleflex P201CN Nippon Polyolefin Co., Ltd. (Water absorbent resin) NVA Polymer (Poly-N-vinylacetamide crosslinked): Noniolex NA-010 Acrylic Polymer (Sodium polyacrylate crosslinked) manufactured by Showa Denko KK: Aquaric CS7S Nippon Shokubai (Compatibilizer) (Dispersant) Stearic acid reagent: Junsei Chemical Co., Ltd. (Compatibilizer) Adtex ER901C: Nippon Polyolefin Co., Ltd.

[0044]

According to the present invention, it is possible to improve the dispersibility of a water-absorbent resin in a thermoplastic resin, and to improve the dispersibility of the thermoplastic resin and the water-absorbent resin, in which a conventional blend of a thermoplastic resin and a water-absorbent resin could not sufficiently exhibit performance. Improvement of thermal stability of water-absorbent resin for applying various molding methods, and aqueous or hydrophilic or aqueous solutions containing acids, alkalis, various salts or organic solvents, which were not possible with conventional water-absorbent resins For various types of packaging that have improved liquid absorbing properties of water-soluble organic solvents, greatly improved the water absorption rate, and have excellent shape retention with no retention of water-absorbent resin after water absorption and no dimensional change in the stretching direction during water absorption. It is useful for films, sheets, fibers, etc. suitable for use in applications in which dimensional changes are unacceptable among materials for civil engineering construction, agricultural and horticultural use, medical use, clothing, daily miscellaneous goods and the like.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tetsuhiko Yamaguchi 1-13-9 Shiba-Daimon, Minato-ku, Tokyo Showa Denko KK F-term (reference) 4F071 AA14 AA22 AA37 AA43 AA54 AA78 AC09 AE18 AF04 AH01 AH03 AH04 AH19 BB07 BB08 BC01 4F210 AA03K AA13K AA29K AA41K AA45K AA49K AB01 AB03 AE01 AE05 AG01 AG14 QA02 QA03 QC02 QC05 QC06 QG01 QG06 QG18 4J002 AA01W BB03W BB05W BB06W BB07W BB08W BB10W BB12W BB15W BB17W BB21W BJ00X BN05W CF06W CF07W CH023 CL00W EF047 EF077 EL137 EV236 EW046 FD313 FD316 GD03 4J100 AG02R AG69R AG71R AJ02Q AL08Q AL09Q AL62R AL65R AM02Q AM21Q AM24R AN04P AN13R AP21Q BA03R BA31Q BA56Q CA04 CA23 DA37 JA19

Claims (11)

[Claims] (1) a thermoplastic resin and (2) the following general formula (I): CH ₂ ＣＨCH—NR ¹ —COR ² (I) (wherein R ¹ and R ² are independently a hydrogen atom or a carbon atom Number 1
3 represents an alkyl group. )) Wherein a water-absorbent resin composition comprising a crosslinked N-vinylcarboxylic acid amide polymer having a repeating unit derived from an N-vinylcarboxylic acid amide monomer represented by the following formula as a main repeating unit is stretched. Stretched body of the water-absorbent resin composition. 2. The water-absorbent resin according to claim 1, wherein the water-absorbent resin contains (2) a crosslinked N-vinylcarboxylic acid amide polymer in an amount of 5 to 400 parts by weight based on 100 parts by weight of the thermoplastic resin. Stretched composition. 3. A water-absorbent resin composition obtained by further adding (3) a dispersant and / or (4) a compatibilizer to the composition, and stretching the water-absorbent resin composition. 3. The stretched water-absorbent resin composition according to 2. 4. An amount of (2) 5 to 400 parts by weight of a crosslinked N-vinylcarboxylic acid amide polymer and (3) an amount of 0.1 to 50 parts by weight based on 100 parts by weight of a thermoplastic resin. The stretched body of the water-absorbent resin composition according to claim 3, comprising 0.1 to 100 parts by weight of a compatibilizer and / or (4) a compatibilizing agent. 5. 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 stretched water-absorbent resin composition according to any one of the above. 6. 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 A water-absorbent resin composition according to any one of claims 1 to 5, which is a crosslinked polymer derived from a polymer mixture and a crosslinking agent having at least two polymerizable unsaturated bonds in one molecule. body. 7. The crosslinking agent is used in an amount of 2 × 10 ⁻⁴ to 1 of the total of monomers.
The stretched body of the water-absorbent resin composition according to claim 6, which is 0 mol%. 8. The stretched water-absorbent resin composition according to claim 1, wherein the N-vinyl carboxylic acid amide is N-vinyl acetamide. 9. A stretched water-absorbent resin composition, characterized in that the water-absorbent resin composition according to any one of claims 1 to 8 is melt-kneaded to form a mixture, and the mixture is molded and stretched. Manufacturing method. 10. The method for producing a stretched water-absorbent resin composition according to claim 9, wherein uniaxial stretching or biaxial stretching is performed in the stretching. 11. The method for producing a stretched water-absorbent resin composition according to claim 9, wherein the stretch is performed at a stretch ratio of 2 times or more.