JP2627075B2 - Water-swellable elastomer composition - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a water-swellable elastomer composition having an improved expansion rate, and more particularly, to an ethylene-propylene copolymer or / and atactic polypropylene, An object of the present invention is to provide a composition comprising a water-soluble resin, a water-absorbent resin, water, a crosslinking agent having two or more functional groups, and an inorganic filler. By molding this into a desired shape, an excellent water-swellable elastomer exhibiting a water-stopping property in a short time in civil engineering and construction-related works can be obtained.

(Prior art) Conventionally, in civil engineering and construction work and other fields, various water-absorbing resins, water-swelling urethane resins, and hydrophilic resins have been added to various rubbers for the purpose of filling gaps, hermetically sealing water and maintaining the airtightness of equipment. Water-swellable rubbers mixed with a rubber having a group have been proposed. For example, a water-swellable composition containing a styrene-based elastomer, a highly water-absorbent resin and a tackifier, (JP-A-60-197784), three components of an elastomer, a water-absorbent resin, and a water-soluble resin are uniformly mixed. Water-swellable elastomer composition (JP-A-60-55041) chlorinated polyethylene,
Water-swellable water-stopping material composed of polyisobutylene and highly water-absorbent resin (Japanese Patent Application Laid-Open No. 61-43641); water-absorbent mixture composed of synthetic rubber, uncrosslinked water-absorbent resin, and water-soluble epoxy compound (Japanese Patent Application Laid-Open No. 61-275338) No.) Many inventions have been disclosed, including a water-swellable water-stopping material formed by molding a composition containing an elastomer, a hydrophilic urethane prepolymer, a liquid rubber containing a hydroxyl group, or a polyethylene oxide (Japanese Patent Application Laid-Open No. 62-256884). All can be used for the same purpose. These are said to have improved problems such as mechanical strength, long-term stability, swelling rate, falling off of the water-absorbent resin, swelling speed, low-temperature workability, and low-temperature swellability. I have.

(Problems to be Solved by the Invention) These conventional water-swellable rubbers are used in civil engineering and construction work as waterproofing materials for joints of shield segment joint surfaces and fume pipes and cardard boxes. When a crack or the like is generated, even if water leakage occurs, it starts to expand following the water leakage to exhibit a water stopping effect. However, many conventional products require a long time from the water leakage to the completion of the water stoppage, and in reality, the water stoppage effect cannot be obtained at an early stage. The invention described in JP-A-60-55041 has been proposed by the present applicant for the purpose of improving the swelling ratio, preventing the water-absorbent resin from falling off, and increasing the swelling speed. Is as low as about 10 to 15% of the saturated swelling ratio up to 24 hours, which is not always satisfactory. Other conventional products, however, require 2 to reach saturation much later than this.
It took ~ 3 days, and it was almost impossible to cope with the above-mentioned water leakage.

The present inventors have conducted intensive studies in view of such a situation, and as a result, have found that an ethylene-propylene copolymer or / and atactic polypropylene, a water-soluble resin,
When a water-absorbent resin, water, a crosslinking agent having two or more functional groups and an inorganic filler are blended, the rate of expansion is extremely high, and the water-swellable elastomer composition has a clean surface with excellent expansion rate and stability. Have been obtained, and the present invention has been achieved.

(Means for Solving the Problems) An object of the present invention is to provide an elastomer which can rapidly expand with water.
A water-swellable elastomer composition comprising ethylene propylene copolymer or / and atactic polypropylene, a water-soluble resin, a water-absorbent resin, water, a crosslinking agent having two or more functional groups, and an inorganic filler.

The elastomer used in the present invention is a natural rubber or a synthetic rubber. As the synthetic rubber, chloroprene rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, fluorine rubber, ethylene propylene rubber, chlorosulfonated polyethylene, silicon rubber , Urethane rubber, polysulfide rubber, acrylic rubber and the like, and from the viewpoint of processability and economy, natural rubber, styrene-
Butadiene rubber is preferred.

Each of these rubbers can be appropriately selected according to the field of use. For example, when weather resistance is required, chloroprene rubber and chlorosulfonated polyethylene are suitable, and when heat resistance is required, silicon rubber and fluorine rubber are suitable.

In the present invention, in order to increase the expansion rate, it is necessary to blend an ethylene propylene copolymer and / or an atactic polypropylene, and a composition containing such a component has not been known conventionally. Although the operation and effect are not obvious, the fact that the expansion speed is significantly increased by this is a main feature of the present invention which can be called an unexpected effect.

The ethylene-propylene copolymer used in the present invention is a rice cake-like substance obtained by polymerizing ethylene and propylene as main components, and has an average molecular weight of 200,000 or less, preferably about 30,000 to 50,000. The atactic polypropylene is usually amorphous and has a waxy or doughy shape, and an average molecular weight of 100,000 or less, preferably about 10,000 to 20,000 is suitable. In any case, those having an excessively high molecular weight become elastomers or plastics and have no effect at all. Either one of these may be used, or both may be used in combination, and are appropriately selected depending on the purpose. In any case, the amount used is 10 to
If the amount is too small, the effect is not exhibited if the amount is too small. On the contrary, if the amount is too large, the effect corresponding to the amount cannot be expected, and the characteristics of the elastomer are lost, which is not preferable. Examples of the water-soluble resin used in the present invention include polyethylene oxide, polyvinyl alcohol,
Synthetic resins such as polyacrylamide, polyvinylpyrrolidone, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose; natural gums such as guar gum, locustine gum, crystal gum, tragacanth gum; and natural products such as sodium alginate and starch. Polyethylene oxide is suitable because it is thermoplastic from the viewpoint of compatibility with rubber and processability. When polyethylene oxide and polyvinylpyrrolidone are used in view of the appearance and performance of the water-swellable elastomer obtained, Good results are obtained. However, in the present invention, it is not always necessary to mix a water-soluble resin, and for example, it is often unnecessary to mix a water-soluble resin with a resin having a high expansion coefficient. Usually, it is used in a proportion of 0 to 50 parts by weight with respect to 100 parts by weight of the elastomer, if necessary. If the amount is too large, adverse effects such as elution tend to occur.

The type of the water-absorbing resin used in the present invention is not particularly limited, and all commercially available ones can be used. Among them, those containing carboxylate as a constituent component of the polymer are convenient for adjusting the water absorbing ability by crosslinking. It is. Examples include cross-linked acrylate polymer, cross-linked vinyl alcohol-acrylate copolymer, cross-linked maleic anhydride-grafted polyvinyl alcohol, cross-linked acrylate-methacrylate copolymer, Crosslinked product of saponified methyl acrylate-vinyl acetate copolymer, crosslinked product of starch acrylate graft copolymer, crosslinked product of hydrolysis product of starch acrylonitrile graft copolymer, starch-ethyl acrylate graft copolymer There are cross-linked products of saponified polymers and cross-linked products of carboxymethyl cellulose.

The amount of water absorbent resin used is 2 per 100 parts by weight of elastomer.
It is preferable to add 5 to 500 parts by weight, preferably 50 to 200 parts by weight.
If the amount of the water-absorbent resin is too small, a sufficient expansion rate and expansion rate cannot be obtained, and if it is too large, the resin is easily detached from the water-absorbent resin or the elastomer, which is not suitable for the purpose of stopping water. In the present invention, in particular, 10 to 100 parts by weight of the water absorbent resin 100 parts by weight.
0.01 to 10 parts by weight, preferably 0.01 to 10 parts by weight in the presence of water by weight
Crosslinking using 5 parts by weight of a crosslinking agent having two or more functional groups can increase the expansion rate in combination with other components. Although the function and effect are not sufficiently evaluated, it is presumed that the hydrophilicity is increased by cross-linking the surface in a state where the water-absorbing resin is slightly swollen, so that the water-absorbing expansion of the entire elastomer is rapidly performed. You.
If the amount of water added is too small, swelling is insufficient, and if it is too large, gelation occurs, which is not preferable for crosslinking. On the other hand, if the amount of the crosslinking agent is too small, the degree of crosslinking is small, and if it is too large, no corresponding effect is exhibited, which is not economically preferable. Here, the water-absorbent resin, water, and the crosslinking agent may be mixed at the same time when the elastomer and other components are mixed. Mixing with an elastomer or the like is preferable because a homogeneous product can be obtained.

As a crosslinking agent used in the present invention, a crosslinking agent having two or more functional groups capable of reacting with other groups present in the polymer, such as carboxylate, hydroxyl group, sulfone group, amino group, etc., as constituents of the water-absorbent resin. Any agent can be used. For example, di- or tri (meth) acrylates of polyols such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin, and N, N-methylenebisacrylamide Examples include bisacrylamides, diglycidyl ether compounds, haloepoxy compounds, isocyanate compounds, N, N ', N "-triacrylisocyanurate, divinylbenzene, etc. Among these, diglycidyl ether compounds are particularly suitable. Specific examples of glycidyl ether compounds include (poly)
There are ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether and the like. Among them, ethylene glycol diglycidyl ether gives the most preferable result.

The inorganic filler used in the present invention is not particularly limited, and those used in ordinary elastomer processing can be used. Examples thereof include diatomaceous earth, bentonite, talc, asbestos, clay, calcium carbonate, and the like. By adding these, physical properties such as workability, dimensional stability, and mechanical strength can be improved. The compounding amount cannot be specified depending on the kind of the elastomer and the kind of the filler. However, the range of 100 to 500 parts by weight is usually preferable with respect to 100 parts by weight of the elastomer. It is not preferable because not only the corresponding effect does not appear but also a disadvantage that it becomes brittle appears.

The composition of the present invention is produced by uniformly mixing the elastomer, ethylene propylene copolymer, water-soluble resin, water-absorbing resin, water, crosslinking agent, and filler by a commonly used mechanical method. For example, roll kneading, Banbury mixer kneading and the like can be mentioned. At this time, needless to say, additives such as a plasticizer, a stabilizer, a bulking agent, a pigment, a vulcanizing agent, and a vulcanization accelerator required for processing the elastomer alone may be appropriately used.

(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 thereto. In addition, the measuring method of the expansion performance in an Example is as follows.

(Expansion coefficient) A test piece made of a water-expandable elastomer and having a size of 20 × 40 mm is immersed in 500 ml of pure water (ion-exchanged water), weighed after a predetermined time, and the expansion coefficient (%) is calculated by the following equation. calculate.

Wo = weight before expansion (g) W = weight after expansion (g) Example 1 Styrene-butadiene rubber [trade name: Nipol 1778J,
Nippon Zeon Co., Ltd.] 137.5 parts by weight (base polymer 100
5 parts carbon black [trade name: Asahi # 50, manufactured by Asahi Carbon Co., Ltd.], ethylene propylene copolymer [trade name: Yucatak K-4, manufactured by Mitsubishi Yuka Co., Ltd.] 150
Part, water-soluble resin polyvinylpyrrolidone (trade name: Luviscol K-17, BASF Japan) 5 parts, diatomaceous earth 150 parts and water-absorbent resin [trade name: Aquakeep 4S, Iron Works Chemical Co., Ltd.]
A mixture of 100 parts of pure water (ion-exchanged water), 50 parts of ethylene glycol diglycidyl ether and 2 parts of zinc oxide, 2 parts of stearic acid, 4 parts of sulfur, and a vulcanization accelerator
1.75 copies of TT [Product name: Noxeller TT, manufactured by Ouchi Shinko Co., Ltd.]
After kneading 0.7 parts of DM (trade name: Noxeller DM, manufactured by Ouchi Shinko Co., Ltd.) with a 6-inch open roll, heat press (150
C. for 30 minutes) to obtain a water-swellable elastomer having a thickness of 2 mm.

Examples 2 to 9, Comparative Examples 1 to 3 Water-swellable elastomers were obtained in the same manner as in Example 1 with the formulations shown in Tables 1 to 3. Examples 1-4, Comparative Examples 1-3
Table 1 shows the results of the measurement of the expansion performance, and Examples 3 to 9 show the results as shown in Table 3.

(Effect of the Invention) The present invention is to provide a water-swellable elastomer having a remarkably high expansion rate, excellent expansion rate and stability, and a clean surface state, and particularly excellent water-swellability in civil engineering and construction-related works. What used to take 2 to 3 days to obtain the saturated expansion coefficient before reaching saturation in an extremely short time of about 1 hour, contributing to the industry as an excellent water-stopping material with an epoch-making effect There is something great to do.

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C08L 33/02 LHR C08L 33/02 LHR (72) Inventor Kosaku Yamada Miyanishi 346, Harima-cho, Kako-gun, Hyogo Prefecture. No. 1 Research Institute of Iron and Steel Chemical Co., Ltd. (72) Inventor Tetsuro Motooka 346 No. 1 Miyanishi, Harima-cho, Kako-gun, Hyogo Pref.

Claims (10)

(57) [Claims] (A) Elastomer consisting of natural rubber or synthetic rubber (B) Ethylene propylene copolymer or / and atactic polypropylene (C) Water-soluble resin (D) Water-absorbing resin (E) Water (F) 2 or more A water-swellable elastomer composition comprising a crosslinking agent having the following functional group: (G) an inorganic filler. 2. (B) 10 to 3 parts per 100 parts by weight of (A).
00 parts by weight, (C) 0 to 50 parts by weight, (D) 25 to 500 parts by weight, (G) 50 to 500 parts by weight, and (E) 10 to 100 parts by weight with respect to (D) 100 parts by weight. The composition according to claim 1, wherein the composition is mixed at a ratio of 0.01 to 10 parts by weight of (F). 3. The composition according to claim 1, wherein the elastomer is a styrene-butadiene rubber. 4. The composition according to claim 1, wherein the ethylene propylene copolymer has an average molecular weight of 200,000 or less. 5. The atactic polypropylene has an average molecular weight.
The composition according to claim 1, which is 100,000 or less. 6. The composition according to claim 1, wherein the water-soluble resin is polyvinylpyrrolidone. 7. The composition according to claim 1, wherein the water-absorbing resin is a crosslinked product of a polyacrylate. 8. The composition according to claim 1, wherein the inorganic filler is diatomaceous earth or bentonite. 9. The composition according to claim 1, wherein the crosslinking agent having two or more functional groups is ethylene glycol diglycidyl ether. 10. The method for producing a composition according to claim 1, wherein a water-absorbing resin, water, and a crosslinking agent having two or more functional groups are mixed in advance, and then mixed with other components. A method for producing a water-swellable elastomer composition, comprising mixing.