WATER-SWELLABLE COMPOSITION

摘要

PURPOSE:To obtain a composition excellent in a rate of water swelling and water swellability, by combining a rubber-like elastomer with a water-insoluble and water-absorptive fiber. CONSTITUTION:A water-swellable composition comprising 100pts.wt. rubber-like elastomer (a) and 3-100pts.wt. water-insoluble and water-absorptive fiber. A preferable rubber-like elastomer is a thermoplastic elastomer having elasticity equivalent to that of a vulcanized natural or synthetic rubber at room temperature and having processability equivalent to that of a thermoplastic resin at high temperature. In particular, a block copolymer comprising a conjugated diene and a vinylaromatic hydrocarbon is desirable. A water-absorptive fiber formed by making a copolymer comprising 70-85wt% acrylonitrile and 15-30wt% carboxyl group-containing comonomer such as acrylic acid into a fiber and converting it into the form of a salt with an alkali metal hydroxide is the most desirable from the viewpoint of stability during processing for obtaining a water-swellable rubber and the water absorptivity and durability of the obtained water-swellable rubber.