THERMOPLASTIC ELASTOMER COMPOSITION AND COMPOSITE MOLDING

PROBLEM TO BE SOLVED: To obtain a thermoplastic elastomer composition and composite moldings that are very elastic as less than 45 Shore durometer hardness as a thermoplastic elastomer, free of such problems as tacky touch and bleeding of a softener, and has higher mechanical strength. SOLUTION: This thermoplastic elastomer composition comprises (a) 100 pts.wt. of a block copolymer composed of polymer blocks (A) consisting of aromatic monoalkenyl or monoalkenylidene hydrocarbon polymers, and polymer blocks B consisting of partially or completely hydrogenated aliphatic conjugated diene hydrocarbon polymers, (b) 50-400 pts.wt. of an oil-extended olefin-based copolymer rubber that contains 20-150 pts.wt. mineral oil-based softener per 100 pts.wt. of the olefin-based copolymer rubber, (c) 2-100 pts.wt. of polyolefin resin, and (d) 50-350 pts.wt. of a mineral oil-based softener, and in order to obtain this thermoplastic elastomer composition, a mixture of the whole quantity of component (b) and a part or while quantity of components (a) and (c) is heat-treated in the presence of an organic peroxide to partially crosslink the polymer mixture.