JPS62285931A - Water-swellable composition - Google Patents

Abstract

PURPOSE:To obtain a composition excellent in a rate of water swelling and water swellability, by combining a rubber-like elastomer with a water-insoluble and water-absorptive fiber. CONSTITUTION:A water-swellable composition comprising 100pts.wt. rubber-like elastomer (a) and 3-100pts.wt. water-insoluble and water-absorptive fiber. A preferable rubber-like elastomer is a thermoplastic elastomer having elasticity equivalent to that of a vulcanized natural or synthetic rubber at room temperature and having processability equivalent to that of a thermoplastic resin at high temperature. In particular, a block copolymer comprising a conjugated diene and a vinylaromatic hydrocarbon is desirable. A water-absorptive fiber formed by making a copolymer comprising 70-85wt% acrylonitrile and 15-30wt% carboxyl group-containing comonomer such as acrylic acid into a fiber and converting it into the form of a salt with an alkali metal hydroxide is the most desirable from the viewpoint of stability during processing for obtaining a water-swellable rubber and the water absorptivity and durability of the obtained water-swellable rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a water-swellable composition having excellent water-swellability, water-absorbing property, water-retaining property and mechanical strength.

[Conventional technology]

Rubber compositions in which polyvinyl alcohol, polyacrylate, carboxymethyl cellulose, hydroxyethyl cellulose, etc. are blended as water-absorbing substances with natural rubber or synthetic rubber are described, for example, in JP-A-53-143653, 4! ! These are known from Japanese Patent Application Laid-open No. 54-7461, Japanese Patent Application Publication No. 54-7463, and Japanese Patent Application Publication No. 54-20066, etc., and because they absorb water and expand, they are known in the field of civil engineering, architecture, and other fields. It is useful as a water-swellable material such as wood. However, such compositions have the disadvantage that, because the water-absorbing substances they contain are water-soluble, they are difficult to dissolve or swell to a high degree with water.

Therefore, in order to overcome all of these drawbacks, it has recently been proposed to incorporate a water-insoluble super absorbent resin into rubber. For such super absorbent resins, see the graph of starch acrylate)! Polymers, vinyl alcohol/acrylate copolymers, crosslinked polyacrylates, etc. are used. For example, Japanese Patent Publication No. 60-41092 discloses a composition in which a water-swellable solid lower olefin-maleic anhydride copolymer crosslinked product is blended with a thermoplastic nidistomer.

[Problem that the invention seeks to solve]

However, the above superabsorbent resin is blended into rubber in the form of particles or powder, and has the disadvantage of slow swelling speed. Methods to increase the swelling rate include blending a large amount of superabsorbent resin or foaming the composition to make a foam-like molded product, but with these methods, the superabsorbent resin falls off from the molded product. There were also problems such as a decrease in the mechanical strength of the molded product.

[Means of problem solving]

The inventor of the present invention has conducted intensive research to obtain a composition that does not have such problems and has excellent swelling speed and swelling properties, and has found that the objective has been achieved by combining water-insoluble water-absorbing fibers with a rubber-like elastic body. They discovered this and completed the present invention.

That is, the present invention includes (a) 100 parts by weight of a rubber-like elastic body (b)
A water-swellable composition comprising 3 to 100 parts by weight of water-insoluble water-absorbing fibers is provided.

The present invention will be explained in detail below.

The rubber-like elastic body of the component (-) used in the present invention is heated at 25°C.
tensile modulus of about 0.05 to s o o o K
q/J, preferably about 0.1 to 2000 Kg/-, and specific examples thereof include natural rubber, synthetic isoprene rubber, butadiene rubber, styrene-butadiene rubber (random matah block), high styrene rubber, and polyester rubber. Butadiene rubber, chloroprene rubber, polybutene rubber, rubbery ethylene-propylene copolymer, ethylene-propylene-diene copolymer rubber, rubbery butadiene-acrylonitrile copolymer, butyl rubber, chlorinated butyl rubber, various nitrile rubbers, rubbery Ethylene-vinyl acetate copolymer, rubbery ethylene-acrylic acid ester copolymer, ethylene-vinyl acetate-acrylic acid ester rubber, rubbery atactic polypropylene resin, rubbery ethylene-acrylic acid ionomer, polyurethane rubber, epichlorohydrin rubber, Chloroprene rubber, fluorine rubber, fluorosilicone rubber, silicone rubber, acrylic ester
7 Acrylonitrile rubber, chlorinated polyethylene rubber, chlorosulfonated polyethylene, polyether rubber, polyolefin-based thermoplastic nidistomer, polyurethane-based thermoplastic nidistomer, polyester-based thermoplastic nidistomer, polyamide-based thermoplastic elastomer, vinyl chloride-based thermoplastic nidistomer, Examples include transpolyoctenamer. Among these rubber-like elastic bodies, thermoplastic nystomers are preferred, which have elasticity similar to that of vulcanized natural rubber or synthetic rubber at room temperature and processability similar to that of thermoplastic resins at high temperatures. Particularly preferred is a block copolymer consisting of a conjugated diene and a vinyl aromatic hydrocarbon.

A block copolymer consisting of a conjugated dient vinyl aromatic hydrocarbon (hereinafter simply referred to as a block copolymer) generally has a vinyl aromatic hydrocarbon content of 5 to 70% by weight,
Preferably it is 10 to 60% by weight. As a method for producing such a block copolymer, for example, Japanese Patent Publication No. 1986-
Examples include methods described in Japanese Patent Publication No. 19286, Japanese Patent Publication No. 43-14979, Japanese Patent Publication No. 49-36957, Japanese Patent Publication No. 48-2423, and Japanese Patent Publication No. 48-4106.

All of these are methods of block copolymerizing a conjugated diene and a vinyl aromatic hydrocarbon using an anionic polymerization initiator such as an organolithium compound in a hydrocarbon solvent, and have the general formula: (A-B)nz A+B- A) n 1
B + A-B ) n (In the above formula, A is a polymer block mainly composed of vinyl aromatic hydrocarbons, and B is a polymer block mainly composed of conjugated diene. The boundary between the OA block and the B block is not necessarily Need to be clearly distinguished (
No sex. Further, n is a number greater than or equal to 1. ) or the general formula, ((B-A) U=X% C(A-E)
n-miteni 1tejni: ;nee=-Xn mjuz 1: (B-A 坩B5-5廼工X, , and X represents a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride, or a residue of an initiator such as a polyfunctional organolithium compound. m and n are integers of 1 or more. ) is obtained as a radial block copolymer represented by
Indicates a copolymer block of a vinyl aromatic hydrocarbon and a conjugated diene and/or a vinyl aromatic hydrocarbon homopolymer block containing the above, and a polymer block mainly containing a conjugated diene is a block containing 50% by weight of a conjugated diene. A copolymer block of a conjugated diene and a vinyl aromatic hydrocarbon and/or a conjugated diene homopolymer block containing an amount exceeding the above. The vinyl aromatic hydrocarbons in the copolymer block may be uniformly distributed or tapered. A plurality of uniformly distributed portions and/or tapered distributed portions may coexist in each copolymer block. The block copolymer used in the present invention may be any mixture of block copolymers represented by the above general formula.

Vinyl aromatic hydrocarbons used in the method of the present invention include styrene, 0-methylstyrene, p-methylstyrene, p-methylstyrene,
Examples include -tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, and vinylanthracene, among which styrene is particularly common.

These may be used not only alone, but also as a mixture of two or more.

The conjugated diene used in the method of the present invention is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 213-dimethyl-1 , 3-butadiene, 1.3
-pentadiene, 1,3-hexadiene, etc.
Particularly common examples include 1,3-butadiene and isoprene. These may be used not only alone, but also as a mixture of two or more.

The molecular weight of the block copolymer used in the present invention is 5.00
0 to 1,000,000, preferably io, ooo
~800.000, more preferably 30.000~50
It is 0.000. In addition, the block copolymer should be used within a range that does not impair its basic properties, such as the effect of improving impact resistance.
hydroxyl group, thiol group, nitrile group, by hydrogenation, halogenation, hydrogen halogenation, or chemical reaction within -
Modifications such as introduction of functional groups such as sulfonic acid groups and amino groups may also be performed. Suitable modified block copolymers include hydrogenated block copolymers and terminally modified block copolymers.

Hydrogenated (hydrogenated) block copolymers are a preferred method of improvement because their heat aging resistance and weather resistance are improved. It is recommended that the block copolymer before hydrogenation has a 2-vinyl bond amount of 20% to 60%, preferably 25% to 50%. Catalysts used in the hydrogenation reaction include (1) Ni, Pt, P
d, metals such as Ru to carbon, silica, alumina,
(2) Ni, Co, Fe;

Cr, etc. organic acid salt or acetylacetone salt and organic,
Homogeneous catalysts are known, such as a so-called Ziegler type catalyst using a reducing agent such as U, or a so-called organic complex catalyst of an organometallic compound such as Ru or Rh.

Specific methods include Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, or Japanese Patent Application Laid-open No. 59-13.
Hydrogenation is performed in the presence of a hydrogenation catalyst in an inert solvent by the method described in Publication No. 3203 to obtain a hydrogenated product,
Hydrogenated block copolymers for use in the present invention can be synthesized. At that time, at least 80 atoms of the aliphatic double bonds based on the conjugated diene compound of the vinyl aromatic compound-conjugated diene compound block copolymer are hydrogenated, and the polymer block mainly composed of the conjugated diene compound is transformed into an olefin. The compound can be converted into a polymer block. In addition, hydrogen of the aromatic double bond based on the vinyl aromatic compound copolymerized with the polymer block A mainly composed of a vinyl aromatic compound and, if necessary, the polymer block B mainly composed of a conjugated diene compound. Although there is no particular restriction on the addition rate, it is preferable that the hydrogenation rate is 20% or less. The amount of unhydrogenated fatty doublets contained in the hydrogenated block copolymer can be easily determined using an infrared spectrophotometer, nuclear magnetic resonance apparatus, or the like.

As the terminal-modified block copolymer, a block copolymer in which a polar group-containing atomic group is bonded to at least one small polymer chain terminal of the block copolymer can be used. By using such a terminally modified block copolymer, mechanical strength can be further improved. Here, the polar group-containing atomic group refers to an atomic group containing at least one atom selected from nitrogen, oxygen, silicon, phosphorus, sulfur, and tin. Specifically, carboxyl group, carbonyl group, thiocarbonyl group, acid no-logenide group, acid anhydride group, carboxylic acid group, thiocarboxylic acid group, aldehyde group, thioaldehyde group, carboxylic acid ester group, amide group, Sulfonic acid group, sulfonic acid ester group, phosphoric acid group, phosphoric acid ester group, amino group, imino group, nitrile group, pyridyl group, quinoline group, epoxy group, thioepoxy group, sulfide group, isocyanate group, inthiophanate group, of·
Examples include atomic groups containing at least one polar group selected from a halogenated silicon group, an alkoxysilicone group, a halogenated tin group, an alkyltin group, a phenyltin group, and the like. More specifically, special application +! The terminal-modified block copolymer described in B 61-1819 can be used.

The water-absorbing fibers used in the present invention have a water absorption rate of 5 times or more, more preferably 10 to 300 times, and a fiber diameter of 0.3 to 2.
300 denier (d) is good, Fl! The dry strength of the fiber is 0.
2 P/d or more, more preferably 11 or more, and is water-insoluble. What is the water absorption capacity here?
This is the saturated water absorption amount (2) per water-absorbing fiber 1. If the water absorption capacity is small, the water absorption and water swelling properties of the composition will be poor, while if the water absorption capacity is too high, the strength of the water-absorbing fibers swollen with water will become too low, which is not preferable. Water-absorbing fibers with a small fiber diameter are difficult to process because the fibers tend to become entangled with each other, while those that are too thick are undesirable because it is difficult to uniformly disperse them in the resin.

Water-absorbing fibers with low dry strength are undesirable because they lower the mechanical strength of the composition mixed with them.

Such water-absorbing fibers include -COOX (X:Li
, Na, K, NH, or amines) in an amount of, for example, 179 mmol/liter, and one method for obtaining this fiber is as shown below, for example.

(1) A method of carbomethoxylating cellulose fibers and then converting them into a salt form with an alkali metal hydroxide, ammonia, or amines. (2) A method of crosslinking acrylic fibers and then hydrolyzing them, or a method of converting acrylic fibers into a high concentration without crosslinking. A method of hydrolyzing while crosslinking with an alkali (3) A method of forming a polymer having a carboxylic acid group or a group that can be converted into a fiber into a form of an alkali metal, ammonium, or amine salt. Among the water-absorbing fibers, 70 to 85% by weight of acrylonitrile and 15 to 30% of a comonomer having a carboxylic acid group such as acrylic acid are used.
After fiberizing the copolymer consisting of % by weight, Li OH,
NaOH.

Water absorption I in salt form with alkali metal hydroxide such as KOH
It is most preferred from the viewpoint of stability during processing since the fibers form a water-swellable rubber and the water absorption and durability of the obtained water-swellable rubber.

The water-insoluble water-absorbing fiber thus obtained is 1 to 1
It is desirable to use it by cutting it into short pieces.

In the water-swellable composition of the present invention, the water-insoluble water-absorbing fiber as component (b) is contained in an amount of 3 to 100 parts by weight, preferably 5 to 70 parts by weight, based on 100 parts by weight of the rubbery elastic body of component (a). part is used. If the amount of component (b) is less than 3 parts by weight, the swelling ratio will be small, and if it exceeds 100 parts by weight, mixing with the rubber-like elastic body will become uneven and the strength after swelling will decrease, which is not preferable.

If necessary, a softener, a thermoplastic resin, etc. can be added to the composition of the present invention to improve processability, hardness, strength, etc. Softeners include lubricating oils, paraffinic process oils, naphthenic process oils, aromatic process oils, paraffin, vaseline, asphalt, vegetable oils (castor oil, cottonseed oil, rapeseed oil, soybean oil, etc.), subs, rosin, fatty acids, etc. can be given. Thermoplastic resins include polyvinyl chloride, polyvinyl bromide, polyvinyl fluoride, polyvinylidene chloride, polyvinyl acetate, chlorinated polyethylene, chlorinated polypropylene, brominated polyethylene, chlorinated rubber, and vinyl chloride-vinyl acetate copolymer. , vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-
Inbutylene copolymer Vinyl chloride-vinylidene chloride copolymer, Vinyl chloride-styrene-maleic anhydride terpolymer, Vinyl chloride-styrene-acrylonitrile copolymer, Vinyl chloride-butadiene copolymer, Vinyl chloride-imprene Copolymer, vinyl chloride-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-maleic acid ester copolymer, vinyl chloride −
Methacrylic acid ester copolymers, chloride and nyl-acrylonitrile copolymers, halogen-containing synthetic resins such as internally plasticized polyvinyl chloride, α-olefin polymers such as polyethylene, polypropylene, polybutyne, poly-3-methylbutene, or ethylene- Polyolefins such as vinyl acetate copolymers, ethylene-propylene copolymers/and their copolymers, polystyrene, acrylic resins, butenes/and other monomers such as maleic anhydride, butadiene,
acrylonitrile, etc.), acrylonitrile-butadiene-styrene copolymer, acrylic ester-butazine-styrene copolymer, methacrylic ester-butadiene-styrene copolymer, or blends and blocks of these resins. Copolymers, graft copolymers, etc. e6 can be obtained.

The composition of the present invention also contains various pigments, dyes, flame retardants,
Antistatic agents, lubricants, plasticizers, inorganic/organic fillers, etc. (For details, see "Practical Additives Handbook for Plastics and Rubber")
(Published by Kagaku Kogyosha) and “Rubber/Plastic Compound Chemicals”
(Additives listed in Rubber Digest, Inc.) can be used.

The composition of the present invention can be manufactured by any conventionally known compounding method.

For example, a melt-kneading method using a general mixing method such as an oven roll, an intensive mixer, an internal mixer, a co-kneader, a continuous kneader with a twin-screw rotor, a -screw or twin-screw extruder, etc., the component (a) is dissolved. Ingredients (
A method of dispersing and mixing b)' and then removing the solvent by heating is used.

〔Example〕

Examples are shown below, but they are representative of the present invention and are not intended to limit the scope of the present invention.

Examples 1 to 3 and Comparative Examples 1 to 3 According to the formulation shown in Table 1. After producing a mixed wire product using a mixing roll, a sheet-like product having a thickness of 2 cm was compression molded, and the tensile strength of the molded product was measured. Further, a 3 cm x 4 cm square test piece was cut out from the sheet and immersed in distilled water for 7 days to measure water absorption. In Table 1, the following water-insoluble water-absorbent fibers and powdered water-absorbent resins were used.

A copolymer containing 78% by weight of acrylonitrile and 22% by weight of acrylic acid was obtained by an aqueous suspension polymerization method using ammonium persulfate and sodium hydrogensulfite as polymerization initiators.

The obtained polymer was spun using 65M dinitric acid, stretched 6 times in hot water at 80 to 90°C, and then
It was dried at 0° C. to obtain a fiber of about 3 d. This fiber was added to a 3 wt% NaOH solution in ethanol containing 40 wt% water.
After soaking for a minute, the fibers were washed with ethanol and dried to obtain water-absorbing fibers. The performance of this water-absorbing fiber was as follows.

Denier: 4.8d Water absorption: 158 Double dry strength: 1.21 The powdered water-absorbing resin is made by cross-linking a copolymer of inbutylene and maleic anhydride with a molar ratio of 1:10 with sodium hydroxide and glycerin glycidyl ether. The water absorption capacity of the powdered water-absorbing resin obtained by pulverizing the cross-linked material and using a 400 mesh powder was approximately 200 times.

The results are shown in Table 1, and the composition of the present invention had excellent tensile strength and a good water absorption rate.

In addition, the compositions of Examples 1 to 3 showed good water retention. Note 1) S: Boristyrine block B; Polybutadiene block B'; Tapered structure butadiene/styrene copolymer block ■ = Isoprene block Note 2) Blend amount based on 100 MiJ parts of block copolymer Note 3) Compliant with JIS K 6872 4)
The water absorption rate was measured by the following method.Examples 4 to 9' Block copolymer paste polymerized in cyclohexane using n-butyllithium as a catalyst, having an fcBABA structure, and having a styrene content of 40 polymers. A terminal-modified block copolymer was prepared by using the polymer with the terminal treatment agent shown in Table 2 and reacting it with a catalyst in equimolar amounts.

Water-absorbing compositions were prepared by the same method as in Example 1 except that these terminally modified block copolymers were used as block copolymers, and their properties are shown in Table 2.

When a terminally modified block copolymer is used, a composition f with even better tensile strength and water absorption can be obtained. A water absorbent composition was produced in the same manner as in Example 1 except for this. The water absorption rates of these are shown in Table 3, and all showed good water absorption. The compositions of Examples 10.16 and 17 were prepared in a conventional manner by adding a conventional vulcanizing agent, vulcanization accelerator, vulcanization accelerating aid, anti-aging agent, lubricant, and carbon black).
Vulcanized material was used.

Table 3 [Effects of the Invention] The water-absorbing composition of the present invention can be used for various purposes by taking advantage of its excellent water absorbency, water swelling property, water retention property, and mechanical strength such as tensile strength and impact resistance. For example, sealing materials, backing materials, waterproofing materials, various types of waterproofing materials, washcloths, oil/water separation materials, sludge solidification materials, dew prevention materials, sweat-absorbing materials, sanitary products, sanitary products such as diapers, cold storage materials, etc. suitable for

Claims (1)

[Claims] 1. (a) 100 parts by weight of rubber-like elastic body (b) 3 to 100 parts by weight of water-insoluble water-absorbing fiber A water-swellable composition consisting of