JPH0336054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-swellable composite material formed by simultaneously extruding and vulcanizing a water-swellable rubber component and a non-swellable rubber component. However, it has good compression resistance with little decrease in water absorption, has directional expansion without impairing the elasticity characteristic of rubber, and has good mechanical strength. The present invention relates to a water-swellable composite material that has excellent performance, such as not peeling when absorbing water.

In recent years, water-swellable substances have been developed and used for various shielding materials, such as sealing materials for steel and other metal structures, prefabricated culvert boxes, shield segments, sealing materials for joints that occur during the assembly of concrete moldings, and sealing materials for concrete pouring joints. It is widely used as a sealing material or a repair sealing material. In particular, compositions made by dispersing superabsorbent resins in 1,3-diene rubber containing 5 to 50% crystalline or glassy regions at room temperature, such as chloroprene rubber, rapidly absorb water and have high It is known that it is useful as a water stop agent by imparting swelling pressure (Japanese Patent Application Laid-open No. 108143/1983). however,
When this composition is subjected to compressive deformation of 30% or more when assembling various structures, the water absorbency of the water-stopping material decreases significantly, and sufficient water-stopping effects cannot be achieved, limiting its use. It has the disadvantage of being

It has also been proposed to use a composite material formed by combining a water-swellable composition as described above and a non-swellable composition mainly composed of, for example, diene rubber, as a water-stopping material.

However, although this material can give directionality to expansion without impairing the elasticity characteristic of rubber and has good mechanical strength, it has the disadvantage of poor compression resistance as mentioned above. are doing.

In view of these circumstances, the present inventors conducted extensive research to develop a water-swellable material with excellent performance, and first developed a combination of chloroprene rubber or chlorosulfonated polyethylene, a superabsorbent resin, and a metal. We have proposed a vulcanized product of a water-swellable rubber component containing a rubber or elastomer that is not vulcanized with an oxide vulcanizing agent and a metal oxide vulcanizing agent. however,
Although this material has good compression resistance such that there is little decrease in water absorption even when it is compressed without absorbing water, its mechanical strength and directionality of expansion are not necessarily satisfactory. Ta.

Therefore, the present inventors attempted to provide a composite formed by simultaneously extruding and vulcanizing the above-mentioned water-swellable rubber component and non-swellable rubber component, but this material did not water-swell upon water absorption. However, it has the disadvantage that it separates into a flexible rubber part and a non-expandable rubber part.

Therefore, as a result of further research, the present inventors found that chloroprene rubber, super absorbent resin, unvulcanized liquid rubber or elastomer that is not vulcanized by metal oxide vulcanizing agent, and metal oxide vulcanizing agent It has been reported that a composite material made by simultaneously extruding and vulcanizing a water-swellable rubber component containing water-swellable rubber component as an essential component and a non-swellable rubber component shows little decrease in water absorption even if it is compressed without absorbing water. It has excellent compression resistance, has directional expansion without impairing the elasticity characteristic of rubber, has good mechanical strength, and does not peel off when water is absorbed. Based on this knowledge, the present invention was completed.

That is, the present invention comprises (A) a water-swellable rubber component and (B)
In a composite material formed by simultaneously extruding and vulcanizing a non-swellable rubber component, the water-swellable rubber component contains (a) 100 parts by weight of chloroprene rubber, and (b) 5 to 5 parts by weight of a superabsorbent resin.
300 parts by weight, (c) 3 to 100 parts by weight of unvulcanized liquid polybutene that is not vulcanized with a metal oxide vulcanizing agent, and
(d) The present invention provides a water-swellable composite material characterized by containing a metal oxide vulcanizing agent as an essential component.

The chloroprene rubber used as component (a) in the water-swellable rubber component in the present invention is obtained by emulsion polymerization of chloroprene, and is a sulfur-modified type,
Non-sulfur modified types are known, and any of them can be used.

In addition, the superabsorbent resin used as the component (b) includes commercially available starch-polyacrylate-based superabsorbent resins, crosslinked polyacrylates obtained by reverse phase polymerization in organic solvents, polyacrylic acid There are super absorbent resins obtained by crosslinking the reaction product of a maleic anhydride copolymer with a basic substance. A high-grade aqueous resin obtained by crosslinking a polymer containing as a monomer component an α,β-unsaturated compound having one or two groups or groups convertible therein in the molecule using a crosslinking agent. suitable.

Examples of the above-mentioned groups that can be converted into carboxyl groups include carboxylate residues, carboxylic acid amide residues, carboxylic acid imide residues, carboxylic acid anhydride residues, and nitrile groups. Examples of α,β-unsaturated compounds having these groups include acrylic acid, methacrylic acid, acrylic amide, methacrylic amide, maleic anhydride, maleic acid, maleic amide, maleic imide, and itaconic acid. , crotonic acid, fumaric acid, itaconic acid, etc., which may be used alone or in combination with other copolymerizable monomers.

Examples of the copolymerizable monomer include ethylene, propylene, isobutylene, 1-butylene, diisobutylene, methyl vinyl ether, styrene, vinyl acetate, acrylic ester, methacrylic ester, acrylonitrile, vinyl chloride, and vinylidene chloride. used. When such monomers are used in combination, the proportion of the α,β-unsaturated compound having a carboxyl group or a group convertible thereto is preferably 30 mol % or more in the total monomer components.

Polymerization of these monomers can be carried out using a radical polymerization catalyst according to a method commonly used in radical polymerization. The thus obtained polymer of monomers having a carboxyl group or a group convertible thereto preferably has a degree of polymerization of 10 to 5,000, but is not necessarily limited to this range. Among such polymers, particularly preferred are polyacrylic acid, polymethacrylic acid, or copolymers of α-olefin or vinyl compounds and maleic anhydride. These polymers or copolymers are preferably made hydrophilic by reacting with compounds of alkali metals or alkaline earth metals such as sodium, potassium, magnesium, calcium, and barium, ammonia, amines, and the like. This reaction is carried out, for example, by dissolving an alkali metal or alkaline earth metal compound, ammonia, an amine, etc. in a suitable solvent, preferably water, and adding the above-mentioned polymer or copolymer into the solution while stirring. be able to. In this case, sodium hydroxide, potassium hydroxide, and ammonia are particularly preferred as the compound to be reacted with the polymer or copolymer in terms of ease of reaction and durability of the superabsorbent resin obtained.

The polymer or copolymer thus obtained is then crosslinked by reacting with a crosslinking agent. As this crosslinking agent, polyvalent epoxy compounds, polyvalent amines, polyvalent alcohols, amino alcohols, polyisocyanates, polyvalent halohydrin compounds, or polyvalent aziridine compounds are used, but particularly preferred are polyvalent epoxy compounds and polyvalent amines. be. Examples of this polyvalent epoxy compound include glycerin diglycidyl ether, ethylene glycol diglycidyl ether, glycerin triglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether. can be mentioned. Further, examples of polyvalent amines include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine having a molecular weight of 5000 or less.

The crosslinking reaction using these crosslinking agents is carried out by adding the crosslinking agent to the above polymer or copolymer and heating if necessary. At this time, an appropriate solvent can be used as desired. When a polyvalent epoxy compound or a polyvalent amine is used as a crosslinking agent, the crosslinking agent is directly added to the reaction mixture of a predetermined polymer or copolymer and an alkali metal or alkaline earth metal compound or ammonia aqueous solution. After the reaction, the product is advantageously separated, dried and further heat treated. At this time, it is necessary to appropriately select the amount of crosslinking agent used and adjust the degree of crosslinking so that a superabsorbent resin having a desired water absorption capacity can be obtained.

If the water absorption capacity of this superabsorbent resin is small, the water absorption capacity of the resulting water-swellable composite material will be small; on the other hand, if the water absorption capacity is too high, the strength of the water-swollen composite material will be low. Does not exhibit significant swelling pressure. Therefore, the water absorption capacity of super absorbent resin is 10
~500 times, preferably 20 to 300 times.

The amount of the superabsorbent resin used in the water-swellable rubber component in the present invention is chloroprene rubber.
5 to 300 parts by weight per 100 parts by weight, preferably 30 to 300 parts by weight
In the range of 200 parts by weight. If this amount is less than 5 parts by weight, the composite material obtained will not be able to function as a water-stopping material, and if it exceeds 300 parts by weight, the strength of the composite material will decrease and it will no longer be able to withstand practical use.

When the unvulcanized liquid polybutene used as component (c) in the water-swellable rubber component of the present invention is co-vulcanized with component (a) or vulcanized by itself, the elastic modulus of the rubber layer increases. When immersed in water, it prevents the superabsorbent resin particles dispersed in the rubber layer from absorbing water and expanding, reducing the expansion ratio of water-swellable composites due to water absorption. It is necessary that the material is not vulcanized by the metal oxide vulcanizing agent used for vulcanization.

The amount of the liquid polybutene used is selected in the range of 3 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of chloroprene rubber. If this amount is less than 3 parts by weight, the compression resistance of the resulting water-swellable composite material will not be obtained, and if it exceeds 100 parts by weight, the strength of the composite material will be so low that it will not be able to withstand practical use.

In the present invention, by using this liquid polybutene, the resulting water-swellable composite material does not separate into a water-swellable rubber portion and a non-swellable rubber portion when water is absorbed. If solid rubber or solid elastomer is used instead of liquid polybutene, the composite material will peel off when it absorbs water.

Further, in the present invention, the above-mentioned liquid polybutene may be used alone, or a mixture of two or more types may be used.

Next, the vulcanizing agent used in the water-swellable rubber component in the present invention is a metal oxide-based vulcanizing agent. A combination of magnesium and zinc oxide is preferred.

In addition, the water-swellable rubber component includes the above-mentioned (a),
In addition to the essential components (b), (c) and (d), if desired, other compounding agents normally used in chloroprene rubber, such as vulcanization accelerators, vulcanization aids, anti-aging agents, Reinforcing agents such as carbon black, white carbon, and clay, inorganic fillers such as calcium carbonate, softening agents such as process oil, plasticizers such as phthalate and sebacate, and coloring agents such as dyes and pigments can be blended. . Particularly when process oil is used in combination, if the amount of oil required for softening is reduced and the amount of liquid polybutene is increased by that amount, the degree of swelling in the thickness direction when processed into a plate will increase. If you increase the amount of oil and reduce the amount of liquid polybutene by that amount,
Since the degree of swelling in the vertical and lateral directions tends to increase, this phenomenon can also be utilized to control the physical properties of the sealing material.

On the other hand, the non-expandable rubber component used in the present invention includes, for example, a diene rubber, a vulcanizing agent, a vulcanization accelerator,
Vulcanization aids, anti-aging agents, reinforcing agents, inorganic fillers,
Other examples include those containing additives commonly used in diene rubbers. As the diene rubber used for this, chloroprene rubber used for the water-swellable rubber component is particularly suitable.

The composite material of the present invention is obtained by simultaneously extruding and vulcanizing the water-swellable rubber component and the non-swellable rubber component using, for example, a double extruder. By compositing in this way, directionality is imparted to expansion without impairing the elasticity peculiar to rubber, and mechanical strength is improved.

The water-swellable composite material of the present invention has good compression resistance such that there is little decrease in water absorption even when it is compressed without absorbing water, and furthermore, it has directionality in expansion, and It has good mechanical strength and has excellent performance such that the water-swellable rubber part and non-swellable rubber part do not separate when water is absorbed, making it a water-stopping material for joints such as shield tunnels and shield segments. , water-stopping material for the joint part of secondary concrete products such as humid pipes and culvert boxes, water-stopping material for the concrete joints of various tunnels, water-stopping material for the joint part of secondary steel products such as U-furium pipes and corrugated pipes, or Can be used as a water stop material for various repairs.

EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way.

The expansion ratio and return ratio in Examples, Reference Examples, and Comparative Examples were determined according to the following methods.

That is, a 2 x 2 cm square sample (thickness 2.8 mm) was cut out from the obtained waterproof material, its weight was measured, (a) it was immersed in water for 7 days, and (b) it was compressed with a hydraulic press to a thickness of 1 mm. After holding it for 3 hours, it was released and immersed in water for 7 days to cause it to expand, its weight was measured, and the expansion ratio and return rate were determined using the following formula.

Expansion ratio (times) = Weight after immersion / Weight before immersion Return rate (%) = Expansion ratio of compressed product / Expansion ratio of uncompressed product x 100 Reference example 1 100 parts by weight of chloroprene rubber, 4 parts by weight of magnesium oxide, activated zinc white 5 parts by weight, 1 part vulcanization accelerator
Parts by weight, 1 part by weight of stearic acid, 2.0 parts by weight of anti-aging agent.
Polybutene HV, which is not vulcanized with a metal oxide vulcanizing agent, is added to a mixture of 20 parts by weight of process oil and 100 parts by weight of a super absorbent resin (having a water absorption capacity capable of absorbing 200 times its own weight of distilled water). -300 was added and kneaded for 20 minutes using a 10-inch test roll to prepare a water-swellable rubber component with a thickness of 3.5 mm.

Next, this rubber component was vulcanized and molded at 170° C. for 10 minutes while being pressurized using a hydraulic press to obtain a sheet-like water stop material with a thickness of 2.8 mm. When the expansion ratio and return ratio were determined for this product when it was not compressed and when it was compressed, they were 16.2 times, 11.6 times, and 72%, respectively.

Reference Example 2 The same formulation as in Reference Example 1 was prepared using a 10-inch test roll for 20 minutes, except that 30 parts by weight of solid elastomer polyisobutylene (Vistanetx MML140) was used instead of 10 parts by weight of polybutene HV-300 in Reference Example 1. After kneading, a water-swellable rubber component with a thickness of 3.5 mm was obtained.

Next, this rubber component was vulcanized and molded at 170° C. for 10 minutes while pressurizing with a hydraulic press to obtain a sheet-like water stop material with a thickness of 2.8 mm. When the expansion ratio and return ratio were determined for this product when it was not compressed and when it was compressed, they were 11.8 times, 11.2 times, and 95%, respectively.

Reference Example 3 A sheet-shaped water stop material was prepared in exactly the same manner as in Reference Example 1, except that liquid polybutene, which is not vulcanized with a metal oxide vulcanizing agent, was not blended. When the expansion ratio and return rate of this product were determined, the expansion ratio without compression was 15.4 times, the expansion ratio with compression was 1.5 times, and the return ratio was 10%.

Example A water-swellable rubber component exactly the same as in Reference Example 1, 100 parts by weight of chloroprene rubber, and 4 parts by weight of magnesium oxide.
Parts by weight, 5 parts by weight of activated zinc white, 2 parts by weight of vulcanization accelerator, 0.5 parts by weight of stearic acid, 3 parts by weight of anti-aging agent, 16 parts by weight of process oil, carbon black
50 parts by weight and a non-expanding rubber component consisting of 30 parts by weight of calcium carbonate were simultaneously extruded and vulcanized using 60 mm and 70 mm double extruders to obtain a composite water stop material.

This material had excellent compression resistance and did not peel off even when immersed in tap water.

Comparative Example 1 A water-swellable rubber component that is exactly the same as in Reference Example 2 and a non-swellable rubber component that is exactly the same as in the example were simultaneously extruded and vulcanized in the same manner as in the example to obtain a composite water stop material. Ta.

Although this product has excellent compression resistance, when it was immersed in tap water, the water-swellable rubber portion and non-swellable rubber portion were separated the next day.

Comparative Example 2 A water-swellable rubber component that is exactly the same as in Reference Example 3 and a non-swellable rubber component that is exactly the same as in the example were simultaneously extruded and vulcanized in the same manner as in the example to obtain a composite water stop material. Ta.

Although this product did not peel off even when immersed in tap water, its compression resistance was extremely poor.

Claims (1)

[Claims] 1. In a composite material formed by simultaneously extruding and vulcanizing (A) a water-swellable rubber component and (B) a non-swellable rubber component, the water-swellable rubber component is (a) chloroprene rubber.
100 parts by weight, (b) 5 to 300 parts by weight of super absorbent resin, (c) 3 to 100 parts by weight of unvulcanized liquid polybutene that is not vulcanized with a metal oxide vulcanizing agent, and (d) metal oxide type. A water-swellable composite material characterized by containing a vulcanizing agent as an essential component.