JP2000129023A - Water-absorbing resin composition foam and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foam excellent in water-absorbability, solvent-absorbability and surface-hydrophilicity by making foaming of a water-absorbing resin composition which contains a thermoplastic resin, a crosslinking substance of an N-vinylcarboxylic acid amide polymer and a foaming agent. SOLUTION: The composition comprises a crosslinking substance of an N- vinylcarboxylic acid amide polymer having a repeating unit based on a monomer represented as CH2=CH-NR1-COR2 (wherein R1 and R2 are H or 1-3C alkyl) as a main repeating unit. The crosslinking substance of an N-vinylcarboxylic acid amide polymer is prepared by using N-vinyl carboxylic acid amide, adding a crosslinking agent to a copolymerizable monomer if necessary, and using a radical initiator without the presence of oxygen. The composition combines usually 5-400 pts.wt. of the crosslinking substance of N-vinylcarboxylic acid amide polymer and 0.1-30 pts.wt. of a foaming agent to 100 pts.wt. of a thermoplastic resin. Further, one can use a dispersant and a compatibilizer. Usually the dispersant is used preferably in an amount of 0.1-50 pts.wt. and 0.1-100 pts.wt. for the compatibilizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-absorbent resin composition foam and a method for producing the same. More specifically, not only pure water (including distilled water, deionized water, etc.) but also acids,
It has good water absorption or solvent absorption performance with respect to aqueous solutions containing alkalis or salts, water-containing organic solvents, and hydrophilic organic solvents.
(100-300 ° C.), which are stable and are required for water absorption and liquid absorption for various packaging, civil engineering, agricultural and horticultural, medical,
The present invention relates to a water-absorbent resin composition foam having a high water absorption rate suitable for use as a material for clothing and daily goods, and having excellent water-absorbent resin retention after water absorption and high water absorption, and a method for producing the same. .

[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 goods, water retention agents for agriculture and horticulture, and other industrial materials such as starch / acrylic acid graft copolymer alkali metal salts, Starch such as saponified starch / acrylonitrile graft copolymer, saponified starch / acrylamide graft copolymer, saponified carboxymethyl cellulose, cellulose / acrylonitrile graft copolymer, alkali metal salt of cellulose / acrylic acid graft copolymer, 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 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 a water absorbent resin, has been studied, and EVA, EEA,
It has been clarified that a polar group-containing thermoplastic resin such as EAA has good dispersibility. 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, in Japanese Patent Publication No. 61-37095, a method of dramatically increasing the water absorption rate by foaming a thermoplastic water-absorbent resin composition has been proposed. However, due to the above-described problems, This foaming ability could not be fully exhibited.

[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, an aqueous solution containing an organic solvent, or a hydrophilic organic solvent, has improved liquid absorbing properties, has a significantly improved water absorption rate, and has excellent thermoplastic resin retention properties after absorbing water. An object of the present invention is to provide a water absorbent resin composition foam 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. A new thermoplastic water-absorbent resin composition foam having excellent water-absorbing performance and solvent-absorbing performance can be obtained by uniformly dispersing in various thermoplastic resins by using a compatibilizer and foaming the composition. And found that the present invention was completed. That is, an object of the present invention is to provide a thermoplastic water-absorbent resin composition foam excellent in water absorption performance, solvent absorption performance, and surface hydrophilicity, and a method for producing the same.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to the following. [1] (1) a thermoplastic resin, (2) the following general formula (I) CH2 = CH-NR1-COR2 (I) (wherein, R1 and R2 independently represent a hydrogen atom or a carbon atom having 1 to 1 carbon atoms)
A cross-linked N-vinylcarboxylic acid amide polymer having, as a main repeating unit, a repeating unit derived from an N-vinylcarboxylic acid amide monomer represented by the following formula (3): A water-absorbent resin composition foam, characterized by foaming a water-absorbent resin composition containing the same. [2] (1) For 100 parts by weight of the thermoplastic resin,
(2) 5 crosslinked N-vinylcarboxylic acid amide polymer
The foamed water-absorbent resin composition according to the above [1], comprising a foaming agent in a proportion of 0.1 to 30 parts by weight, and a foaming agent in a proportion of 0.1 to 30 parts by weight. [3] (1) thermoplastic resin, (2) the following general formula (I) CH2 = CH-NR1-COR2 (I) (wherein, R1 and R2 independently represent a hydrogen atom or a carbon atom having 1 to 1 carbon atoms)
A cross-linked N-vinylcarboxylic acid amide polymer having a main repeating unit derived from an N-vinylcarboxylic acid amide monomer represented by the following formula: 4) a dispersant, and (5)
A foamed water-absorbent resin composition, characterized by foaming a water-absorbent resin composition containing a compatibilizer. [4] (1) 100 parts by weight of thermoplastic resin, (2)
5 to 40 crosslinked N-vinylcarboxylic acid amide polymer
0 parts by weight, (3) 0.1 to 30 parts by weight of a foaming agent, (4)
The water absorbent resin composition foam according to the above [3], comprising 0.1 to 50 parts by weight of a dispersant and 0.1 to 100 parts by weight of a compatibilizer (5). [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 water-absorbent resin composition foam as described in Crab. [6] N-vinyl carboxylic acid amide polymer crosslinked product,
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 foam according to any one of the above [1] to [5], which is a crosslinked polymer derived from a crosslinking agent. [7] A crosslinked product of an N-vinylcarboxylic acid amide polymer is
The N-vinylcarboxylic acid amide monomer represented by the general formula (I) or a monomer mixture containing the monomer in an amount of 70% by weight or more, and at least two polymerizable unsaturated bonds in one molecule. The water-absorbent resin composition foam according to any one of the above [1] to [5], which is a crosslinked polymer derived from a crosslinking agent. [8] The crosslinking agent is 2 × 10 −4 to 10 mol% of the total monomer
The water-absorbent resin composition foam according to the above [6] or [7]. [9] The foamed water-absorbent resin composition according to any one of the above [1] to [8], wherein the N-vinylcarboxylic acid amide is N-vinylacetamide. [10] The water-absorbent resin composition according to any one of [1] to [9] 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 extruded and foamed. A method for producing a water-absorbent resin composition foam, comprising:

The crosslinked product of the 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. And the crosslinking agent (C) is added to the total of the above, and the production can be carried out 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-
Examples thereof include vinylformamide and N-methyl-N-vinylacetamide. Among them, N-vinylacetamide is particularly preferable from the viewpoints of water absorption, solvent absorption, stability, and the like. 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 ( Salts), (meth) acrylates of lower alkyl (C4 or less) substituted by a dimethylamino group, (meth) acrylates of lower alkyl (C4 or less) substituted by a hydroxyl group, acrylonitrile, etc. Among them, acrylic acid (salt), acrylamido-2-methylpropanesulfonic acid (salt), vinylsulfonic acid (salt) and acrylonitrile 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.

[0008] The N-vinylcarboxylic acid amide of the above-mentioned polymer cross-linked product (including a copolymer cross-linked product; the same applies hereinafter) has a
-50% by weight or more, preferably 70% by weight or more of the total of the monomers (monomer mixture) composed of vinylcarboxylic acid amide and comonomer. For example, if the compounding ratio of N-vinylcarboxylic acid amide and sodium acrylate is 100: 0, the water absorption ratio of a 1.0% by weight CaCl2 aqueous solution changes depending on the crosslink density and the degree of polymerization with respect to its own weight. Is about 50 times, and if this is 70:30, about 35 times.

The method of measuring the water absorption capacity referred to here is as follows: 2.0 g of a crosslinked polymer is poured into about 1 liter of a liquid (1.0 g wt% CaCl ₂ aqueous solution) and water is absorbed until it is saturated. Is a numerical value calculated by the following equation. Water absorption ratio = [(weight of swollen polymer crosslinked product) / (weight of used polymer crosslinked product)]-1

Specific examples of the cross-linking agent (C) having at least two polymerizable unsaturated bonds in one molecule (hereinafter referred to as a cross-linkable compound) used in the production of the cross-linked polymer include: Multiple (meth) such as N, N'-methylenebisacrylamide, triethylene glycol (meth) acrylate, pentaerythritol tri (meth) acrylate
Compounds having an acrylic group, N, N'-alkylenebis (N-vinylcarboxylic amide) compounds such as N, N'-butylenebis (N-vinylacetamide), diethylene glycol diallyl ether, trimethylolpropane triallyl ether, tetraallyl Oxyethane,
Compounds having two or more allyl groups such as pentaerythritol triallyl ether, diallyl adipate, diallyl terephthalate, divinyl oxalate, divinyl succinate, divinyl malonate, divinyl adipate, divinyl maleate, trivinyl citrate, pyromeritium Compounds having two or more vinyl ester structures such as tetravinyl acid, and the like.
More than one species can be used.

The amount of the crosslinking agent used is 2 × 10 −4 to 2 × 10 −4 based on the total amount of monomers in consideration of gel strength and water absorption.
10 mol% is preferable, and the range of 5 * 10 <-4> to 2 mol% is more preferable.

[0012] The polymerization initiator used in the production of the above crosslinked polymer may be a conventionally known peroxide, an organic or inorganic peracid or a salt thereof and an azobis compound, or various polymerization initiators thereof. Redox-based initiators in combination with a reducing agent are used, and among these, azobis-isobutyronitrile, azobis (2-amidinopropane) and azobis-based initiators such as basic acid salts 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 0.1.
The time is about 5 to 30 hours, but 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 of the N-vinylcarboxylic acid amide polymers produced by the above 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. Tend to be able to.

[0015] 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 / 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.), carboxylic acid metal bases (sodium salt, calcium salt, magnesium salt, zinc salt, etc.), At least one selected from a carboxylic acid ester group (eg, a methyl ester group, an ethyl ester group, a propyl ester group, a butyl ester group, a vinyl ester group), an acid anhydride group (eg, a maleic anhydride group), an epoxy group, and an oxazoline group; It is a polyolefin having various functional groups. Examples of the polyolefin as a raw material include the above-mentioned polyolefins.

Specific examples of such 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, 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. 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 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 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. 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 these may be used alone or in combination of two or more 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 their derivatives 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, good dispersion can be achieved without using a compatibilizer, but Japanese Patent Application Laid-Open Nos. 10-53631 and
Graft-modified thermoplastic polyesters, graft-modified polyamides and the like as shown in JP-A-139836 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 foaming agent used in the present invention is used for foaming the thermoplastic water-absorbent resin composition to improve the water absorption rate, water retention, and the like. What is used in resin is used. For example, sodium bicarbonate, ammonium carbonate,
Inorganic blowing agents such as ammonium bicarbonate, ammonium nitrite, azide compounds, sodium boron hydride and azodicarbonamide, trihydrazinotriazine, p-
Toluenesulfonyl semicarbazide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, barium azodicarboxylate, 4,4'-oxybis (benzenesulfonylhydrazide), paratoluenesulfonylhydrazide, diazoaminobenzene, N, N ' −
Dimethyl-N, N'-dinitrosoterephthalamide, nitrourea, acetone-p-toluenesulfonylhydrazone, P-toluenesulfonylazide, 2,4-toluenedisulfonylhydrazide, P-methylurethanebenzenesulfonylhydrazide, trinitrosotrimethylenetriamine , Oxalyl hydrazide, nitroguanidine,
Chemical blowing agents consisting of organic blowing agents such as hydrazodicarbonamide, and organic hydrocarbons such as butane, pentane, hexane and heptane, chlorofluorocarbons, chlorinated hydrocarbons, inorganic carbon dioxide, nitrogen gas, air, etc. A physical foaming agent or the like is used. Furthermore, it is preferable to add a foaming aid to the foaming agent, adjust the decomposition temperature and decomposition rate of the foaming agent, and carry out foam molding suitable for various thermoplastic resins.

The mixing ratio of each component in the thermoplastic water-absorbent resin composition of the present invention is as follows: (1) 100 parts by weight of the thermoplastic resin, and (2) 5 to 5 parts of the crosslinked N-vinylcarboxylic acid amide polymer. The proportion is 400 parts by weight, preferably 10 to 200 parts by weight, and (3) the proportion of the foaming agent is 0.1 to 30 parts by weight, preferably 0.3 to 20 parts by weight. Furthermore, (4)
When a dispersant and (5) a compatibilizer are used, (4) a dispersant of 0.1 to 50 parts by weight, preferably 2 to 35 parts by weight,
And (5) a compatibilizer in an amount of 0.1 to 100 parts by weight, preferably 2 to 50 parts by weight.

In the present invention, the thermoplastic water-absorbent resin composition is extruded and foamed. The thermoplastic water-absorbent resin composition of the present invention is obtained by extruding a powder, a compatibilizing agent, a foaming agent and a thermoplastic resin obtained by coating a solid fine particle of a liquid absorbing agent with a dispersant before the extrusion molding, by a usual extrusion for thermoplastic resin. It can be manufactured by kneading with a machine. In this case, it can be produced by charging a thermoplastic resin, N-vinylcarboxylic acid amide-based polymer fine particles coated on the surface with a dispersant and a compatibilizer to an extruder. 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.
Any method may be employed, in which the mixture is directly formed in the melt-kneading section of the molding machine at the time of extrusion molding, but the former in which the mixture is formed in advance before extrusion molding is preferred.

The extrusion molding is carried out by a conventional method for thermoplastic resins, for example, a T-die molding method, an inflation molding method, a calendar molding method, a filament molding method, etc., and the composition is a film-like material such as a film or a sheet. , A ribbon, a fiber, or the like. As for the foaming method, a conventional method for a thermoplastic resin is used. For example, at the stage of producing the above-mentioned thermoplastic water-absorbent resin composition, a chemical foaming agent is added in advance, or at the stage of subjecting the composition to extrusion molding after the production of the composition, the above-mentioned chemical foaming agent is added. Or, by the method of extrusion foaming the composition, or the method of foaming after extrusion, or
At the stage of extrusion molding, a method of injecting a physical foaming agent such as carbon dioxide gas, alternative Freon gas, heptane or the like to extrude and foam is used. Among these, the method of extrusion foaming is preferred.

This water-absorbent resin composition is formed into a shape suitable for a portion to be used, and is usually arranged in a gap between structures such as a cable covering material, a tunnel, and a building, and water that passes through the gap is used. , It expands by contact with seawater or the like to close the gap, thereby 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, a water-absorbing material, etc. utilizing its water-absorbing performance. In that case, a single film,
As a sheet, preferably as a laminated film with other materials, as a sheet, or woven, for food packaging, chemical packaging, agricultural and horticultural use, dew condensation prevention, building materials such as interior, sanitary products, oil-water separation And antistatic applications. In addition, water-soluble organic solvents such as lower alcohols such as methanol and ethanol, lower 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 aldehydes such as acetaldehyde. The N-vinylcarboxylic acid amide-based polymer (liquid absorbing agent) of the present invention absorbs liquid even in an aqueous solution containing
Since it expands, it can be effectively used as such a solvent-based liquid-absorbing material, water-stopping material, and packing.

[0034]

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. (Production Example) 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, and 200 ml / min. Then, 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
Polymer) was obtained.

The test method is described below. (1) Foaming ratio Using a test piece of a fixed shape collected from each sheet, it was calculated by the following equation. Expansion ratio = (density of resin composition before expansion) / (density of resin composition after expansion) (2) Water absorption ratio 23 ° C. using a test piece of a fixed shape collected from each sheet
, Was immersed in each aqueous solution, and its volume was measured at predetermined intervals, and calculated by the following equation. Water absorption ratio = {(weight of water-absorbing foamed resin composition) / (weight of dry foamed resin composition used)} − 1

Examples 1 to 19 Comparative Examples 1 and 2 N-vinylcarboxylic acid amide polymer fine particles and a dispersant were added to a Henschel mixer at the compounding ratios shown in Table 1,
After mixing at 100 ° C. for 15 minutes, the obtained mixture, the compatibilizer and the thermoplastic resin were melt-kneaded with a vented co-directional twin-screw extruder (inner diameter 30 mm, L / D = 42) to produce pellets. . Temperatures suitable for various thermoplastic resins (Table 1
), And foaming was performed with a single screw extruder to obtain a foamed sheet.

[0037]

[Table 1]

Next, the expansion ratio and the water absorption ratio of the foamed sheet thus obtained were measured. Table 2 shows the results. As is clear from Table 2, Examples 1 to 1
Sample No. 9 has a larger water absorption capacity with a salt aqueous solution such as artificial seawater than the comparative example, and shows that these water solutions have excellent water absorption (water stoppage) performance.

[0039]

[Table 2]

The used resins and the like 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 Kagaku Co., Ltd. Styrac 301 Styrene-butadiene block manufactured by Asahi Kasei Corporation Copolymer: SBS / JSR TR2900 Nippon Synthetic Rubber Co., Ltd. SBS hydrogenated product: SEBS / Clayton G1726X Shell Chemical Co., Ltd. Styrene-isoprene block copolymer: JSR / SIS 5000 Nippon Synthetic Rubber Co., Ltd. Olefin-based thermoplastic elastomer: Santoprene 201-64 AIES Co., Ltd. Vinyl chloride-based thermoplastic elastomer: Samprene F8807-1 Mitsubishi Chemical Vinyl Co., Ltd. Polyurethane thermoplastic elastomer: Elastollan ET-260R Polyamide thermoplastic elastomer made by Takeda Birdish Co., Ltd .: Pebax 2533 Polyester thermoplastic elastomer made by Toray Industries: Perprene P-30B Fluoroplastic thermoplastic made by TOYOBO Elastomer: Daiel Thermopla T-630, manufactured by Daikin Industries, Ltd. Acrylic polymer (crosslinked sodium polyacrylate): Aqualic CS7S, manufactured by Nippon Shokubai Co., Ltd. Compatibilizer) Adtex ER901C: manufactured by Nippon Polyolefin Co., Ltd. (dispersant) Stearic acid reagent: manufactured by Junsei Chemical Co., Ltd. (blowing agent) ADCA (azodicarbonamide): vinyl alcohol AC Polywalen manufactured by Eiwa Chemical Industry Co., Ltd .: polysulene EE- 201 Eiwa Chemical Industry Co., Ltd. Baking soda: Cerbon SC-P Eiwa Chemical Industry 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 decrease start temperature (° C.) Nitrogen air NVA polymer 350 330 Crosslinked sodium polyacrylate 250 210 Thus, the N-vinylcarboxylic acid amide-based polymer has good thermal stability. Since a heat stabilizer (antioxidant and the like) is not added to the measurement sample, the stability is further increased by several tens of degrees Celsius by adding the stabilizer.

[0042]

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, civil engineering, agricultural and horticultural applications, medical use, and clothing that have improved the liquid absorbency of the organic solvent and greatly improved the water absorption rate, and have excellent retention of the water-absorbent resin after water absorption It is intended to provide a thermoplastic water-absorbent resin foam in the form of a film, sheet, fibrous or the like suitable for use as a material for daily necessities and the like, and a method for producing the same.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 39/00 C08L 39/00 67/00 67/00 77/00 77/00 101/00 101/00 (72) Invention Person Atsushi Suzuki 3-2 Chidori-cho, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture F-term (reference) 4F074 AA16 AA25 AA28 AA32 AA50N AA65 AA71 BA01 BA14 BC01 CA22 CC04X CC22X CC32X DA02 DA33 DA38 DA46 DA53 DA59 4J002 BB03W BB05W BB06W BB08W BB09W BB12W BB15W BB17W BB21W BB23W BC04W BC06W BJ00X BN05W BP03W CF06W CF07W CL01W CL03W CL05W DE016 DE216 DE226 EA016 EF007 EF128 EG017 EH008 EH017 EH058 EH078 EH108 EL138 EP008 EP026 EQ026 EQ036 ES006 ET006 ET016 EU186 EV247 EV257 EV286 EW127 FD207 FD208 FD317 FD326 GA00 GB01 GG02 GL00

Claims (10)

[Claims] (1) a thermoplastic resin; (2) the following general formula (I): CH2 = CH-NR1-COR2 (I) (wherein, R1 and R2 are each independently a hydrogen atom or a group having 1 to 1 carbon atoms)
A cross-linked N-vinylcarboxylic acid amide polymer having, as a main repeating unit, a repeating unit derived from an N-vinylcarboxylic acid amide monomer represented by the following formula (3): A water-absorbent resin composition foam, characterized by foaming a water-absorbent resin composition containing the same. 2. (1) 5 to 400 parts by weight of a crosslinked N-vinylcarboxylic acid amide polymer, and (3) 0.1 to 30 parts by weight of a foaming agent, based on 100 parts by weight of a thermoplastic resin. The water-absorbent resin composition foam according to claim 1, which is contained in a ratio of 1 part by weight. (1) a thermoplastic resin, (2) the following general formula (I) CH2 = CH-NR1-COR2 (I) (wherein, R1 and R2 independently represent a hydrogen atom or a carbon atom
A cross-linked N-vinylcarboxylic acid amide polymer having a main repeating unit derived from an N-vinylcarboxylic acid amide monomer represented by the following formula: 4) a dispersant, and (5)
A foamed water-absorbent resin composition, characterized by foaming a water-absorbent resin composition containing a compatibilizer. 4. An amount of (2) a crosslinked N-vinylcarboxylic acid amide polymer of 5 to 400 parts by weight and an amount of (3) a foaming agent of 0.1 to 30 parts by weight based on 100 parts by weight of the thermoplastic resin. Parts, (4) 0.1 to 50 parts by weight of a dispersant, and (5)
4. A composition comprising a compatibilizer in an amount of 0.1 to 100 parts by weight.
Water-absorbent resin composition foam according to 4. 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 water absorbent resin composition foam 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 the monomer in an amount of 50% by weight or more. The water-absorbent resin composition according to any one of claims 1 to 5, which is a crosslinked polymer derived from a monomer mixture and a crosslinking agent having at least two polymerizable unsaturated bonds in one molecule. Foam. 7. 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 at least 70% by weight of the monomer. The water-absorbent resin composition according to any one of claims 1 to 5, which is a crosslinked polymer derived from a monomer mixture and a crosslinking agent having at least two polymerizable unsaturated bonds in one molecule. Foam. 8. The crosslinking agent is used in an amount of 2 × 10 -4 to 1
The water-absorbent resin composition foam according to claim 6 or 7, which is 0 mol%. 9. The foam according to claim 1, wherein the N-vinylcarboxylic acid amide is N-vinylacetamide. 10. A mixture obtained by melt-kneading the water-absorbent resin composition according to claim 1 at a temperature not lower than the melting point or glass transition point of the thermoplastic resin, and extruding the mixture to form a foam. A method for producing a water-absorbent resin composition foam, comprising: