WATER-SWELLABLE COMPOSITION

摘要

PURPOSE:To provide a water-swellable compsn. which little causes shrinkage on drying after it expands by absorbing water and is suitable for use as a sealing material, by blending a hydraulic material with a water-swellable material. CONSTITUTION:A hydraulic material such as portland cement or blast furnace cement is blended with a water-swellable material to obtain the desired water- swellable compsn. Examples of the water-swellable materials are water-swellable urethane resins and carboxymethylcellulose. Preferred water-swellable urethane resins are those derived from water-swellable urethane prepolymer contg. isocyanate groups at its terminals obtd. by reacting an ethylene oxide/propylene oxide random/block polymerized polyoxyalkylene glycol with an org. diisocyantate. Pref. the water-swellable urethane resin is used together with a rubber such as natural rubber or synthetic rubber.