C.i. Kasei Company, Limited

Hiroharu Sasayama

Yuji Ishihara

Michiyoshi Terauchi

Shozo Otsugu

Takashi Kushida

The inventive water-swellable caulking material for water-leakage prevention is of the type formed of a composition comprising a rubbery polymer and a highly water-absorptive resin and useful in the caulking works of a construction joint of concrete. Different from the conventional caulking materials of the type, the inventive caulking material is provided on the surface of a shaped body of the water-swellable composition with a coating film which is impervious to neutral water but exhibits water-permeability when contacted with an alkaline water of an alkalinity such as in an uncured concrete mixture so that the caulking material is prevented from premature or untimely expansion by swelling even when inadvertently contacted with water prior to application to the working site but capable of promptly expanding when contacted with an uncured concrete mixture with alkalinity.

Water-swellable caulking material for water-leakage prevention

The waterstop used to prevent passage or leakage of water through a construction joint of concrete is shaped of a plastic or rubber in the form of a continuous-length belt-like form and provided with a water-swellable rubbery layer on at least a portion, or, for example, along the peripheries of the belt-like form, side-by-side coming into contact with the concrete bodies to serve as a water-tight filling of the joint by being swollen with water. The water-swellable rubbery layer is protected temporarily prior to use with a coating film of an alkali-soluble polymeric material which can at least partially be dissolved away by the alkalinity of the water in the concrete joint. The peripheries of the plastic- or rubber-made belt-like form are preferably in a length-wise bulged form having a bore running therethrough to serve as a stress absorber when the water-swellable rubbery layer is swollen with water. The disclosure also includes a particularly preferred water-swellable rubbery composition formed of a matrix comprising an acrylonitrile-butadiene rubber, polyvinyl chloride resin and chlorinated polyethylene and a dispersed phase of a water-swellable crosslinked polymer.

Waterstop

A self-swelling leakage-preventing material is produced by reacting under heat a mixture of a copolymer of a lower olefin such as isobutene with maleic anhydride, a polymer emulsion having compatibility with the copolymer, such as an acrylic polymer emulsion, and a compound having at least two functional groups in a molecule selected from the group consisting of a hydroxy group, amino group and epoxy group, such as ethylene glycol, until a crosslinked product having a swelling ratio of 5-40 times is obtained. The mixture itself may be shaped into a suitable form prior to the reaction. A core material such as a non-woven fabric may be impregnated with the mixture prior to the reaction.

Process for the preparation of self-swelling leakage-preventing materials

A self-swelling leakage-preventing material is produced by reacting under heat a mixture of a copolymer of a lower olefin such as isobutene with maleic anhydride, a polymer emulsion having compatibility with the copolymer, such as an ethylene-vinyl acetate copolymer emulsion, and a compound having at least two functional groups selected from the group consisting of hydroxyl groups, amino groups and epoxy groups, such as ethylene glycol, until a cross-linked product having a swelling rate of 5-40 times is obtained. The mixture itself may be shaped into a suitable form prior to the reaction. A core material such as a non-woven fabric may be impregnated with the mixture prior to the reaction.

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Ageo, Japan

Hiroharu Sasayama