JPH0832866B2 - Water-expandable water blocking material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-swellable water-stop material. More specifically, the present invention has a good water-absorbing ability even for an aqueous solution containing an electrolyte, which is formed by blending two or more kinds of water-absorbing resins having different water-absorbing ability with an elastomer, and has an excellent water-stopping effect. The present invention relates to a water-expandable water-stopping material that can be exerted.

Conventional technology Water-stopping materials are used in civil engineering and construction work for mortar, concrete construction and cracks in water pipe connections.
It is widely used to stop water leakage by filling gaps that cause water leakage such as cracks and gaps.

As such a water blocking material, conventionally, a water-swellable composition,
For example, a resin composition has been developed, which comprises a vulcanized product of a mixture of a highly water-absorbent resin, a diene rubber, a vulcanizing agent, a vulcanization accelerator, a filler, an antioxidant, etc., which expands in contact with water, or With such a water-swellable composition, a specific expansion composition,
For example, diene rubber, vulcanizing agent, vulcanization accelerator, filler,
It has been proposed to combine a vulcanizate of a mixture such as an anti-aging agent to stop water (JP-A-57-108143 and JP-A-57-135160).

Further, a water-swellable composition in which a highly water-absorbent resin is contained in a flexible plastic such as ethylene-vinyl acetate copolymer is also known (JP-A-55-3424).

A water-stop material composed of such a water-swellable composition expands by contact with water, closes the leaking gap due to the high expansion pressure, and effectively stops the water, so that it is easy to apply and has an excellent stopping property. It is highly desirable because it gives a water effect.

However, the water-stopping material comprising the conventional water-swellable composition generally has a remarkably small water-absorbing ability with respect to an aqueous solution containing an electrolyte as compared with the water-absorbing ability with respect to ordinary water, and therefore has a drawback that it has poor water-stopping ability with respect to seawater and the like. have.

Further, a water-absorbent composition obtained by dispersing a nonionic low water-absorbent resin or an electrolyte low-water-absorbent resin in natural rubber or synthetic rubber may have a small difference in water-absorbing ability for an aqueous solution containing an electrolyte and distilled water. Although it is known, it has a drawback that it is inferior in water-stopping performance because it has a low water-absorption capacity itself and a high expansion pressure cannot be obtained.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention solves the drawbacks of the water-stopping material comprising such a conventional water-swellable composition and has a good water-absorbing ability even in an aqueous solution containing an electrolyte such as seawater. The present invention aims to provide a water-swellable water-stop material having excellent water-stopping effect.

Means for Solving the Problems As a result of various studies, the inventors of the present invention have found that the objective can be achieved by blending an elastomer with a predetermined amount of each of a high water-absorbing resin and a low water-absorbing resin. The inventors have found the present invention and completed the present invention based on this finding.

That is, the present invention relates to (A) 100 parts by weight of an elastomer, and (B) at least one kind of highly water-absorbent resin having a water absorption capacity of 40 times or more of its own weight against distilled water and less than 40 times less water-absorbing resin than its own weight. A water-absorbent resin mixture containing, wherein the low water-absorbent resin is a polymer electrolyte highly crosslinked product, and the content thereof is in the range of 50 to 90% by weight of 20 to 250.
The present invention provides a water-swellable water-stop material comprising a composition blended by weight.

The elastomer used in the present invention is a natural rubber, a synthetic rubber, a synthetic resin having flexibility, and the like. Examples of the synthetic rubber include polyisoprene rubber, polybutadiene rubber, styrene-diene random copolymer rubber, acrylonitrile-diene copolymer rubber. And diene rubbers such as chloroprene rubber, isobutylene-isoprene copolymer rubber and ethylene-propylene-diene copolymer rubber. Further, as the synthetic resin having flexibility, for example, chlorinated polyethylene, chlorosulfonated polyethylene,
Ethylene-vinyl acetate copolymer, soft polyvinyl chloride,
Examples include polyurethane. These elastomers may be used alone or in combination of two or more.

In the present invention, it is necessary to use at least one kind of highly water-absorbent resin and at least one water-absorbent resin in combination as the water-absorbent resin. As the high water-absorbent resin, those having a water absorption capacity for distilled water of 40 times or more of its own weight, preferably 100 to 800 times are used, and as the low water absorbent resin, the water absorption capacity for distilled water is 40 times its own weight. Less than one is used.

Examples of the super absorbent polymer include commercially available starch-
Polyacrylic acid salt-based super absorbent polymer, cross-linked product of polyacrylic acid salt obtained by reverse phase polymerization in organic solvent, copolymer of vinyl alcohol and acrylic acid, copolymer of isobutylene and maleic anhydride A highly water-absorbent resin obtained by cross-linking the reaction product of the above-mentioned basic substance is used.
Among them, in particular, from the viewpoint of durability of the water blocking material obtained, an α, β-unsaturated compound having one or two carboxyl groups or groups capable of being exchanged with the carboxyl group in the molecule is a monomer component. A highly water-absorbent resin obtained by crosslinking the polymer contained as above with a crosslinking agent is suitable.

As the low water-absorbent resin, for example, polyacrylic acid or a salt thereof, a maleic anhydride copolymer or a salt thereof, or the like,
Low water absorption obtained by highly cross-linking an electrolyte polymer containing, as a monomer component, an α, β-unsaturated compound having one or two carboxyl groups or groups capable of being converted into it with a cross-linking agent Resin is used.

Regarding the ratio of the high water-absorbent resin to the low water-absorbent resin, it is necessary that the amount of the low water-absorbent resin is in the range of 50 to 90% by weight based on the total amount of the water-absorbent resin. This amount is 50% by weight
If the water-stopping material obtained is less than the above, the difference between the water-absorbing ability for ordinary water and the water-absorbing ability for an aqueous solution containing an electrolyte is large, and the effect of the present invention is not exhibited. The water absorption capacity itself is reduced, resulting in poor water blocking performance.

In the present invention, the water-absorbent resin is an elastomer 100
It is necessary to add 20 to 250 parts by weight, preferably 50 to 200 parts by weight to the parts by weight. If this amount is less than 20 parts by weight, the water-blocking material obtained will have poor expandability, and if it exceeds 250 parts by weight, the strength will be low and the hardness will be high, resulting in poor workability.

Explaining an example of a preferred method for producing the water-swellable waterproof material of the present invention, when using a flexible synthetic resin such as chlorinated polyethylene as an elastomer,
This and a high water-absorbent resin and a low water-absorbent resin are each blended in a predetermined amount, and if necessary, an antioxidant, an ultraviolet absorber,
After the additive components such as a reinforcing agent, an inorganic filler, a softening agent, a plasticizer, and a colorant are mixed and sufficiently kneaded, the resulting mixture is extrusion-molded or press-molded to obtain the waterproof material. To be .

As the elastomer, for example, when a diene rubber is used, a diene rubber, a superabsorbent resin and a low absorbent resin are blended in respective predetermined amounts, and if necessary, the additive component or the diene rubber is usually used. By vulcanization molding using a vulcanization material for diene rubber, a vulcanization accelerator, a vulcanization aid, etc.
The water blocking material is obtained.

Effects of the Invention The water-swellable water-stop material of the present invention has good water-swellability,
Moreover, the difference between the water absorption capacity for normal water and the water absorption capacity for aqueous solutions containing electrolytes such as seawater is small, and it is particularly effectively used to prevent water leakage such as seawater.For example, in civil engineering and construction work, shield segment joint surface Used for filling joints such as pipes and prefabricated culvert boxes, and gaps such as joints of concrete structures.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

The expansion ratio and the retention rate of the water blocking material were determined as follows.

That is, a 2 × 2 cm square sample with a thickness of 3 mm was cut out from the obtained waterproofing material, and the weight was measured, and then (1) immersed in tap water for 30 days (2) immersed in synthetic seawater for 30 days. Inflate under each condition, measure its weight,
The expansion ratio and the retention rate were calculated by the following formulas.

Examples 1 and 2 and Comparative Examples 1 to 4 100 parts by weight of chloroprene, low water-absorbing resin, high water-absorbing resin in an amount as shown in the attached table, 4 parts by weight of magnesium oxide,
5 parts by weight of zinc oxide, 1 part by weight of vulcanization accelerator, 1 part by weight of stearic acid, and 2 parts by weight of antioxidant with a 10-inch test roll.
After kneading for 20 minutes, a compound having a thickness of 3.5 mm was obtained. Next, this compound was vulcanized at 170 ° C. for 10 minutes while being pressed by a hydraulic press to prepare a sheet-shaped water-expandable waterproof material having a thickness of 3.0 mm. The expansion ratio and retention rate of this water blocking material are shown in the table.

 The types of water-absorbent resin in the table are as follows.

KI- × 15: Kuraray Isoprene Chemical Co., Ltd., isobutylene-maleic anhydride crosslinked product Approximately 15 times water absorption capacity against distilled water KI-201K: Kuraray Isoprene Chemical Co., Ltd., isobutylene-maleic anhydride crosslinked product against distilled water Water absorption ratio approx. 200 times SP-520: Sumitomo Chemical Co., Ltd., Poval-polyacrylic acid copolymer Water absorption ratio against distilled water approx. 500 times CS-40: Nippon Shokubai Chemical Co., Ltd., polyacrylic acid crosslinked product Distillation Water absorption capacity of about 200 times As can be seen from this table, the retention rate is
40% or more. Comparative Examples 1 and 2 each have a retention rate of 71.
% And 50%, the absolute value of the expansion ratio is small, and the retention rates of Comparative Examples 3 to 6 are as small as 30% or less.

Claims (2)

[Claims] Claims: (A) 100 parts by weight of the elastomer,
(B) A water-absorbent resin mixture containing at least one highly water-absorbent resin having a water absorption capacity of 40 times or more its own weight and less than 40 times its water absorption capacity against distilled water, wherein the low water-absorbent resin is A water-swellable water-stop material comprising a composition in which 20 to 250 parts by weight of a polymer electrolyte highly crosslinked product and a content of the polymer electrolyte are in the range of 50 to 90% by weight. 2. The water-stopping material according to claim 1, wherein the highly water-absorbent resin has a water absorption capacity for distilled water of 100 to 800 times its own weight.