| 摘要 |
PROBLEM TO BE SOLVED: To obtain a water absorption rate improver for a water swellable rubber, having a low content of soluble organic carbon and a higher water absorption rate than that of a conventional rubber and suitable for a water stop material, etc., by including an inorganic compound, containing an aluminum silicate and having a prescribed specific surface area and a prescribed average particle diameter therein. SOLUTION: This water absorption rate improver comprises an inorganic compound, containing aluminum silicate and having the specific surface area within the range of 1-10m<2> /g and the average particle diameter within the range of 0.1-100μm and further preferably zeolite and/or pumiceous sand expanded grains. The water swellable rubber is preferably produced by formulating (B) 5-50 pts.wt. water absorbing resin prepared by copolymerizing a monomer component containing an acrylic or a methacrylic ester-based monomer of the formula [R is H or methyl; X is a 2-4C oxyalkylene at >=50mol% molar fraction of oxyethylene based on the total oxyalkylene; Y is a 1-5C alkoxy, phenoxy, etc.; (n) is 3-100] and (C) 0.1-10 pts.wt. water absorption rate improver for the water swellable rubber with (A) 100 pts.wt. elastomer such as polybutadiene polymer.
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