JP2000313761A - Web-like water-absorbing sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject sheet excellent in water absorbing performance or the like, useful as a film for various wrapping uses, by homogeneously dispersing an N-vinylcarboxylic acid amide-based polymer crosslinked product in a thermoplastic polyolefin followed by foaming and opening the resultant composition. SOLUTION: This web-like water-absorbing sheet is obtained by foaming and opening a composition comprising a thermoplastic polyolefin (e.g. polypropylene), an N-vinylcarboxylic acid amide-based polymer crosslinked product having a monomer of the formula CH2=CH-NR1-CO-R2(R1 and R2 are each H or a 1-3C alkyl) (e.g. N-vinylacetamide) as constitutive unit, and a foaming agent (e.g. sodium bicarbonate) at the weight ratio of 100:(1-400):(0.1-30). Also, it is preferable that a dispersant (e.g. a primary amine salt) and a compatibilizer [e.g. (meth)acrylic acid] are added to the composition at the weight ratio of (0.1-50):(1-100).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a web-shaped water-absorbent sheet obtained by foaming and opening a water-absorbent resin composition and a method for producing the same. In more detail, 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, a hydrophilic organic solvent, etc. It has liquid absorption performance and is stable even at high molding processing temperature (about 180-300 ° C),
Various types of packaging, civil engineering and construction, transportation, agricultural and horticultural use, medical care, clothing, bedding, sanitary materials, daily miscellaneous goods, shoes, accessories, etc. A water-absorbent resin composition having a very high water-absorbing rate, which is suitable for use as a material, has a very high water-absorbing speed, is excellent in retaining the water-absorbent resin after absorbing water, does not separate under some pressure, and has flexibility. 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 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-absorbing, and are in powder form. Furthermore, in recent years, the use of water-absorbent resins has been steadily expanding, and there has been a demand for water-absorbent resins not only in powder form but also in forms such as films, sheets, thick plates, and fibers. strong. However, the current water-absorbent resin has no thermoplasticity because it is a cross-linked product,
Processing into a thick plate, fiber, etc. was extremely difficult. Further, water-absorbent resins that can be formed into films and fibers have been studied, but they have not always been satisfactory in terms of water absorption and stability. 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.

[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 a disadvantage that, by introducing a polar group, thermal stability at a high temperature is deteriorated, and mechanical properties, chemical resistance and the like are reduced as compared with a homopolymer. Had. Further, the water-absorbing resin itself also has poor thermal stability at high temperatures, and thermal decomposition progresses due to prolonged residence at high temperatures (180 to 300 ° C.) during molding or melt-kneading, resulting in a very low water absorption. In addition, there were great restrictions on the selection of thermoplastic resin and molding conditions. Further, the water-absorbent resin has sufficient water-absorbency with respect to pure water containing no electrolytes or ions (regardless of suspended substances), and has a swelling property, but is not limited to acids, alkalis, and various water-soluble salts. For example, it has a problem that water absorption is greatly reduced with respect to an aqueous solution or seawater containing electrolytes and ions, and the water absorption performance is greatly changed depending on the solution. Was. On the other hand, Japanese Patent Publication No. 61-37095 proposes a method for dramatically increasing the water absorption rate by foaming a water-absorbing resin composition. However, the above-mentioned acid resistance, alkali resistance, water absorption stability, etc. Problem still remained.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has greatly improved the water absorption rate, which was insufficient with a conventional composition of a thermoplastic resin and a water-absorbing resin. It improves the retention of the water-absorbent resin after water absorption, and has excellent absorption properties for aqueous solutions containing acids, alkalis, various salts, and organic solvents or hydrophilic organic solvents, which were insufficient with conventional water-absorbent resins. It is an object of the present invention to provide a web-shaped water-absorbing sheet formed by foaming and opening a water-absorbent resin composition which has liquid performance, does not separate under some pressure, and is flexible, and a method for producing the same.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have developed a cross-linked N-vinyl carboxylic acid amide polymer having good water absorption performance against an aqueous solution containing an acid, alkali or various salts and good heat stability at high temperatures. If necessary, add a dispersant and a compatibilizer, and uniformly disperse them in various thermoplastic polyolefins.
Furthermore, by mixing the composition with a foaming agent and expanding the foam, it is possible to obtain a web-like expanded foam of a thermoplastic water-absorbing resin composition having excellent instantaneous water absorption performance and solvent absorption performance. And completed the present invention.

That is, the present invention relates to the following matters. [1] (1) thermoplastic polyolefin, (2) the following general formula (I) CH ₂ ＣＨCH—NR ¹ —CO—R ² (I) (wherein, R ¹ and R ² independently represent a hydrogen atom or carbon Number 1
3 represents an alkyl group. (3) a crosslinked 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 formula (3): and (3) a foaming agent. A web-shaped water-absorbing sheet obtained by foaming and opening a resin composition. [2] (1) 1 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 polyolefin. A web-shaped water-absorbent sheet obtained by foaming and opening the water-absorbent resin composition according to the above [1], which is contained in a proportion. [3] The above composition is further subjected to (4) a dispersing agent and / or (5) a compatibilizing agent, and the water-absorbent resin composition according to the above [1] or [2] is foamed and spread. Web-shaped water-absorbing sheet. [4] (1) 1 to 400 parts by weight of the crosslinked N-vinylcarboxylic acid amide polymer, (3) 0.1 to 30 parts by weight of the foaming agent, based on 100 parts by weight of the thermoplastic polyolefin. (4) The water-absorbent resin composition according to the above [3], which contains the dispersant in an amount of 0.1 to 50 parts by weight and / or (5) the compatibilizing agent in an amount of 0.1 to 100 parts by weight, is foamed and spread. Web-shaped water-absorbing sheet. [5] An N-vinylcarboxylic acid amide polymer crosslinked product 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. A web-shaped water-absorbent sheet obtained by foaming and opening the water-absorbent resin composition according to any one of the above [1] to [4], which is a polymer cross-linked product derived from the cross-linkable compound. [6] The crosslinkable compound in the crosslinked product of the N-vinylcarboxylic acid amide polymer is 2 × 10 ⁻⁴ to 10 mol% of the total monomer.
A web-shaped water-absorbent sheet obtained by foaming and opening the water-absorbent resin composition according to the above [5]. [7] A web-shaped water-absorbent sheet obtained by foaming and opening the water-absorbent resin composition according to any one of [1] to [6], wherein the N-vinylcarboxylic acid amide is N-vinylacetamide. [8] Web-shaped water absorption obtained by subjecting the water-absorbent resin composition according to any one of the above [1] to [7] to extrusion foaming and stretching, wherein the water-absorbent resin composition is foamed and spread. Sheet manufacturing method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Further, the present invention will be described in detail. The crosslinked product of the N-vinylcarboxylic acid amide polymer used in the present invention is a comonomer having a copolymerizability with the above-mentioned (A) N-vinylcarboxylic acid amide or, if necessary, (B) N-vinylcarboxylic acid amide. (C) a crosslinking agent (hereinafter, also referred to as a “crosslinkable compound”) to a mixture of the above monomers, and can be produced by using a radical polymerization initiator under substantially oxygen-free conditions. . (A) Examples of N-vinylcarboxylic acid amide include N-vinylacetamide, N-vinylformamide, N-methyl-N-vinylformamide, N-methyl-N-vinylacetamide, N-ethyl-N-vinylacetamide and the like. Among them, N-vinylacetamide is particularly preferred from the viewpoints of water absorption or solvent absorption, stability and the like. At least one of these is used.

(B) Comonomers having copolymerizability with N-vinylcarboxylic acid amide include (meth) acrylamide, (meth) acrylic acid (salt), (meth) acrylamido-2-methylpropanesulfonic acid (salt) , Vinyl sulfonic acid (salt), allyl sulfonic acid (salt), (meth) acrylic acid ester of lower alkyl (C4 or less) substituted by dimethylamino group, and lower alkyl (C4 or less) substituted by hydroxyl group ( (Meth) acrylic acid ester, acrylonitrile, etc. Among them, acrylamide,
Acrylic acid (salt), acrylamido-2-methylpropanesulfonic acid (salt), vinylsulfonic acid (salt) and acrylonitrile. These salts include sodium salts, potassium salts, ammonium salts and the like,
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 the sum of monomers (monomer mixture) composed of N-vinylcarboxylic acid amide and a comonomer. It is at least 50% by weight, preferably at least 70% by weight.

Specific examples of the (C) crosslinkable compound having at least two polymerizable unsaturated bonds in one molecule used for producing the above polymer crosslinked product include N, N'-methylenebisacrylamide, Ethylene glycol di (meth) acrylate, pentaerythritol tri (meth)
Compounds having a plurality of (meth) acryl groups such as acrylates; N, N'-alkylenebis (N-vinylcarboxylic amide) compounds such as N, N'-butylenebis (N-vinylacetamide); diethylene glycol diallyl ether; trimethylol Compounds having two or more allyl groups such as propane triallyl ether, tetraallyloxyethane, pentaerythritol triallyl ether, diallyl adipate, diallyl terephthalate, divinyl oxalate, divinyl succinate, divinyl malonate, divinyl adipate, Compounds having two or more vinyl ester structures, such as divinyl maleate, trivinyl citrate, and tetravinyl pyromellitate, can be used, and one or more of these can be used as needed. The amount of the (C) crosslinkable compound to be used is 2% based on the total amount of monomers in consideration of gel strength and water absorption.
It is preferably from × 10 ⁻⁴ to 10 mol%, more preferably from 5 × 10 ⁻⁴ to 2 mol%.

[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. 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
The time is about 30 hours, but it is not particularly limited as long as the desired polymer crosslinked product is obtained. Although the polymerization process is not necessarily limited, an aqueous solution polymerization method, a reversed-phase suspension polymerization method, a reversed-phase emulsion polymerization method, and the like, which are conventionally used as a method for producing a crosslinked sodium polyacrylate, can be used. As specific examples, the methods described in JP-A-3-223304, JP-A-4-230250, JP-A-4-346833, and the like can be employed. After the N-vinyl carboxylic acid amide copolymer is produced by the above method, the functional group is
It may be produced by post-crosslinking by reacting various epoxy compounds, alcohols, amines, isocyanates, divalent or higher valent metal ions and the like with a functional group derived from a comonomer.

The N-vinylcarboxylic acid amide polymer crosslinked product 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 not particularly limited, but is usually 500 μm or less, preferably 100 μm or less, more preferably 50 μm or less. If the particle size is larger than 500 μm, the dispersibility in the thermoplastic polyolefin is poor, and the liquid absorbing agent is excessively separated from the thermoplastic polyolefin when swollen with an aqueous solvent or the like, or large irregularities are present on the surface of the thermoplastic polyolefin. It is not preferable because it can be done.

The thermoplastic polyolefin used in the present invention includes a polyolefin or a modified polyolefin. Examples of the polyolefin include polypropylene, polyethylene, polybutene, poly-4-methylpentene-1, ionomer, ethylene / propylene copolymer, ethylene / hexene copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer Further, a copolymer containing a small amount of a diene is exemplified, and these may be used alone or in combination of two or more.

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.) ), 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 at least one functional group. 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) ) Copolymers and maleic anhydride-grafted SEPS (styrene / ethylene / propylene / styrene) copolymers.
More than one species may be used in combination.

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. 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 / 1.
It is preferable to select from those within the range of 0 minutes. Polyolefins containing various elastomers, lubricants, plasticizers, stabilizers, antistatic agents, pigments and other additives can be used as long as the effects of the present invention are not impaired.

In the present invention, a dispersant is used to uniformly disperse solid fine particles of an N-vinylcarboxylic acid amide-based polymer crosslinked product (hereinafter also referred to as "water-absorbing polymer") in a thermoplastic polyolefin. be able to. If the difference between the two is large, 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. This is a concept similar to the dispersion of inorganic fine particles in thermoplastic polyolefin, 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. 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 fine particles of the water-absorbing polymer or the dispersant surrounding the fine particles and the thermoplastic polyolefin, and increases the mechanical strength. It is used to improve properties, 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-
Examples thereof include 1,2-dicarboxylic acids and acid anhydrides, esters, half-alkyl esters, amides, and imides thereof, and α, β-unsaturated dicarboxylic acids and derivatives thereof are particularly preferable. Compounds containing these functional groups may be used alone or in combination of two or more. Further, as the compatibilizer, a modified polyolefin having the above functional group can be used. In the case of the modified polyolefin, a good dispersion state can be obtained without using a compatibilizer.

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-toluenesulfonylhydrazon, P-toluenesulfonylazide, 2,4-toluenedisulfonylhydrazide, P-methylurethanebenzenesulfonylhydrazide, trinitrosotrimethylenetriamine , Oxalyl hydrazide, nitroguanidine,
Chemical blowing agents consisting of organic blowing agents such as hydrazodicarbonamide, and physics of organic hydrocarbons such as butane, pentane, hexane and heptane, chlorofluorocarbons, chlorinated hydrocarbons, inorganic carbon dioxide, nitrogen and air A foaming agent or the like is used.

Further, a foaming aid is added to the foaming agent,
It is preferable to adjust the decomposition temperature and decomposition rate of the foaming agent and to carry out foam molding suitable for various thermoplastic resins. The expansion ratio is not particularly limited, but is preferably 1.5 times or more in order to obtain a highly water-absorbent resin composition. In order to obtain a water-absorbent resin composition having instantaneous water absorption properties and exhibiting a high water absorption ratio, the expansion ratio is preferably 3 times or more.

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 a thermoplastic polyolefin and (2) 1 to 400 parts by weight of a crosslinked N-vinylcarboxylic acid amide polymer. Parts, preferably 10-200
Parts by weight, (3) the foaming agent is 0.1 to 30 parts by weight, preferably 0.3 to 20 parts by weight. Further, when (4) a dispersant and (5) a compatibilizer are used, (4) a dispersant is added in an amount of 0.1.
1 to 50 parts by weight, preferably 2 to 35 parts by weight, and (5) 0.1 to 100 parts by weight, preferably 2 to 100 parts by weight of the compatibilizer.
It is preferably used in a proportion of 50 parts by weight.

The expanded foam of the water-absorbent resin composition according to the present invention may be prepared by mixing a fine powder of a water-absorbing polymer with a dispersant, a compatibilizer, a foaming agent, The polyolefin is obtained by premixing the polyolefin using a Henschel mixer, a super mixer or a tumbler type mixer as necessary, foaming and extruding the mixture by a known extrusion molding method, inflation molding method, or the like, and further stretching by air cooling. Foam extrusion is preferably in a state close to overfoaming, and in the cooling step after foam extrusion,
It is preferable to cool while adjusting the viscosity so that the foamed portion is easily broken by air cooling. If it is rapidly cooled and solidified by water cooling or the like, it is difficult to obtain a desired expanded foam even if it is stretched. In addition, normal rubber compounding such as reinforcing agents such as carbon black, inorganic fillers such as calcium carbonate, softeners such as process oils and plasticizers such as esters, and amine-based and phenol-based antioxidants during molding. Can be added at the same time. Further, various additives such as an antibacterial agent, a fungicide, an insect repellent, and a repellent may be added according to the use.

The web-shaped liquid-absorbent sheet obtained by foaming and opening the water-absorbent resin composition of the present invention may be formed by laminating with another material (thermoplastic resin, paper, or the like) according to the application. Alternatively, a multilayer sheet may be used. At that time, if necessary, the intermediate layer may be bonded using an adhesive component. The web-shaped liquid-absorbent sheet obtained by foaming and opening the water-absorbent resin composition of the present invention is not only a water-stopping agent and a sealing material,
It can also be used as a water retention material, a water absorption material, etc., taking advantage of its flexibility, water absorption and water retention. In that case, as a single film or sheet, or as a multilayer body, for food packaging, chemical packaging, agricultural and horticultural use, dew condensation prevention, interior building materials, sanitary goods, daily goods, oil / water separation, electrification For prevention,
It can be applied to fields such as shoe interiors and accessories. Furthermore, lower alcohols such as methanol and ethanol,
Aqueous solutions containing water-soluble organic solvents such as 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, and the hydrophilic solvents themselves Also, the water-absorbent resin composition of the present invention absorbs liquid at a high speed and expands, so that it can be effectively used as such a solvent-based liquid-absorbing material, liquid-retaining material, water-stopping material, and packing.

[0025]

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) Liquid absorption ratio 23 ° C. using a test piece of a fixed shape collected from each sheet
Was immersed in each solution for a predetermined time, centrifuged at 3,000 rpm for 10 minutes using a centrifuge, weighed, and calculated by the following equation. Liquid absorption ratio = ｛(weight of foamed resin composition absorbed) / (weight of foamed resin composition used)｝ − 1

Examples 1 to 3 Comparative Examples 1 and 2 Water-absorbing resin, dispersant, foaming agent, compatibilizer and thermoplastic polyolefin were added to a mixing machine such as a Henschel mixer or a super mixer in the mixing ratio shown in Table 1. , 15 minutes 1
After mixing at 00 ° C., the resulting mixture is
Approximately 220 ° C. using an mφ twin screw extruder (Example 1 only: approx.
(70 ° C.). At that time, ADCA was used as a foaming agent. Air velocity 10m / s after T-die protrusion
ec forcible cooling with air and take-up speed 2m / min
Then, a web-like water-absorbent sheet obtained by spreading a cotton-like foam was obtained.

[0028]

[Table 1]

Next, the expansion ratio and the water absorption ratio of the web-shaped liquid-absorbing sheet obtained by expanding the foam were measured. Table 2 shows the results. As is clear from Table 2, Examples 1 to 3 have a larger absorption capacity with a saline solution such as artificial seawater or ethanol and ethanol with respect to the comparative example, and have excellent liquid absorption / water retention performance with these aqueous solutions. Is shown.

[0030]

[Table 2]

The resins and the like used are shown below. (Thermoplastic polyolefin) PP (polypropylene): J-Alomer MA210 EVA (ethylene vinyl acetate copolymer) manufactured by Nippon Polyolefin Co., Ltd .: JELEX EVA VH450W (water-absorbing resin) manufactured by Nippon Polyolefin Co., Ltd. NVA-based polymer (poly N-vinylacetamide) Crosslinked product): Noniolex NA-010 Acrylic acid-based polymer (sodium polyacrylate crosslinked product) manufactured by Showa Denko KK: Company A salt-resistant type (compatibilizer) Adtex ER901C: Nippon Polyolefin Co., Ltd. (dispersant) stearin Acid reagent: manufactured by Junsei Chemical Co., Ltd. (blowing agent) ADCA (azodicarbonamide): manufactured by VINIHOLE AC Eiwa Chemical Co., Ltd.

[0032]

According to the present invention, a conventional blend of a thermoplastic resin and a water-absorbent resin could not exhibit sufficient performance.
Significant improvement in water absorption rate, excellent retention of water-absorbent resin after water absorption, excellent flexibility, and contains acids, alkalis, various salts or organic solvents, etc. that were not possible with conventional water-absorbent resins Various types of packaging, civil engineering, agricultural and horticultural, medical, etc. that can instantly absorb aqueous solutions and even hydrophilic organic solvents.
It is useful as a film, sheet, fibrous or the like suitable for clothing, daily goods and the like.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tetsuhiko Yamaguchi 1-13-9 Shibadaimon, Minato-ku, Tokyo F-term in Showa Denko KK 4F074 AA16 AA22 AA24 AA53 AD10 AG17 AG20 BA13 CA22 CC02Z DA33 DA37 DA38 DA45 DA46 DA53 DA59 4J100 AN04P BA14P CA01 CA31 HA53 HC29 HC34 HC50 JA19 JA51 JA64 JA67

Claims (8)

[Claims] (1) a thermoplastic polyolefin; (2) the following general formula (I): CH ₂ ＣＨCH—NR ¹ —CO—R ² (I) (wherein R ¹ and R ² are independently hydrogen atoms Or carbon number 1
3 represents an alkyl group. (3) a crosslinked 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 formula (3): and (3) a foaming agent. A web-shaped liquid-absorbing sheet obtained by foaming and opening a reactive resin composition. 2. 1 to 400 parts by weight of (2) a crosslinked N-vinylcarboxylic acid amide polymer and (3) 0.1 parts by weight of a foaming agent per 100 parts by weight of a thermoplastic polyolefin.
The web-shaped water-absorbent sheet obtained by foaming and spreading the water-absorbent resin composition according to claim 1, wherein the water-absorbent resin composition is contained in an amount of from 30 to 30 parts by weight. 3. The water-absorbent resin composition according to claim 1 or 2, further comprising (4) a dispersant and / or (5) a compatibilizer. Web-shaped water-absorbing sheet. 4. (1) 1 to 400 parts by weight of a crosslinked N-vinylcarboxylic acid amide polymer and (3) 0.1 to 100 parts by weight of a thermoplastic polyolefin.
30 parts by weight, (4) 0.1 to 50 parts by weight of dispersant and / or
Or (5) a web-shaped water-absorbent sheet obtained by foaming and opening the water-absorbent resin composition according to claim 3, wherein the water-absorbent resin composition is contained in an amount of 0.1 to 100 parts by weight. 5. A crosslinked product of an N-vinylcarboxylic acid amide-based polymer comprising at least one N-vinylcarboxylic acid amide monomer or a monomer mixture containing 50% by weight or more of the monomer. A web obtained by foaming and opening the water-absorbent resin composition according to any one of claims 1 to 4, which is a crosslinked polymer derived from a crosslinkable compound having two polymerizable unsaturated bonds. Water absorbing sheet. 6. The crosslinkable compound in the N-vinylcarboxylic acid amide polymer crosslinked product is 2 × 10 ^-4 to 1 of the total monomer.
A web-shaped water-absorbent sheet obtained by foaming and opening the water-absorbent resin composition according to claim 5 in an amount of 0 mol%. 7. A web-shaped water-absorbent sheet obtained by foaming and opening the water-absorbent resin composition according to claim 1, wherein the N-vinylcarboxylic acid amide is N-vinylacetamide. 8. A web formed by foaming and expanding the water-absorbent resin composition, wherein the water-absorbent resin composition according to any one of claims 1 to 7 is extruded and foamed, and further stretched. A method for producing a water-absorbing sheet.