C.i. Kasei Company, Limited

Kuraray Isoprene Chemical Co. Ltd.

Kuraray Co., Ltd.

Kurary Isoprene Chemical Co., Ltd.

Yoshihiro Yoshioka

Hiroshi Harima

Kazuhiro Takasaki

Toshihiro Kimura

Motokazu Nishimura

The invention provides a novel watertight rubbery sealing material of which the water-swellability is markedly insusceptible to the adverse influence of compression of the material in a dry condition. The watertight sealing material is a shaped and vulcanized body of a water-swellable rubber composition comprising, in a limited proportion, (a) a chloroprene rubber, (b) a highly water-absorptive resin such as a crosslinked polyacrlylic acid in the form of a sodium salt, (c) a rubbery polymer unvulcanizable with a metal oxide-based vulcanizing agent and (d) a metal oxide-based vulcanizing agent which is preferably a combination of magnesium oxide and zinc oxide.

Compression-resistant water-swellable rubber composition and watertight

A water-absorbing rubber composition comprising (A) a 1,3-diene rubber with a crystal or glass region content as measured at an ordinary temperature of 5-50% and (B) a highly water-absorbing resin dispersed in the said rubber, the said highly water-absorbing resin being a product of crosslinking of a polymer which contains as monomer component thereof at least 40 mole percent of an .alpha.,.beta.-unsaturated compound containing 1 or 2 groups each selected from the class consisting of a carboxyl group and a group convertible to a carboxyl group with at least one crosslinking agent selected from the class consisting of a polyfunctional epoxy compound and a polyamine, the resin being in the form of a powder capable of passing through a 20-mesh Tyler screen and absorbing 20-500 times its own weight of distilled water. The composition can absorb water rapidly and produce a high swelling pressure, and has good durability in the swollen state.

Water-absorbing rubber composition

The invention provides a novel water-swellable polymeric composition useful as a leakage-preventing material filling an interstice, for example, in a concrete body or at a pipe joint. The polymeric composition comprises (a) a hydrophilic or water-soluble polymer having carboxyl groups in the molecule, (b) a water-soluble epoxy compound having at least two epoxy groups per molecule and (c) a rubbery polymer as blended with the components (a) and (b) in the form of an aqueous dispersion, e.g. a rubber latex, having been dried and subjected to a heat treatment, preferably, as impregnating a fibrous core material.

Water-swellable composition and leakage preventing material therewith

The invention provides a novel water-swellable caulking material which is a composite body of stratified structure composed of at least one rubbery layer swellable in water comprising highly water absorbing resin dispersed in the matrix of a rubber and at least one rubbery layer not swellable in water integrally bonded together, which latter serves to resist the expansion of the former layer when swollen in water in the directions other than the direction perpendicular to the plane of the layers. The inventive caulking material can exhibit unexpectedly excellent water sealing effect with easiness in handling in addition to the rapidity in water absorption by virtue of the structure thereof preventing the expansion of the material in the directions of length and width without decreasing the expansion in the direction of thickness.

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Ibaraki, Japan

Yoshihiro Yoshioka