RUBBER-MODIFIED STYRENIC RESIN COMPOSITION, EXPANDABLE RESIN PARTICLE PREPARED THEREFROM, AND FOAMED MOLDING

摘要

PROBLEM TO BE SOLVED: To provide a rubber-modified styrenic resin compsn. and expandable resin particles having a good moldability and capable of giving foamed molding excellent in impact resistance. SOLUTION: This compsn. comprises a continuous phase formed of a polystyrene resin and a disperse phase comprising diene rubber particles contg. a polystyrene resin. The diene rubber has a cis-bonding content of 80% or higher, and in the rubber, (i) the limiting viscosity numberηof the toluene-solubles is 0.5-0.7; (ii) the degree of swelling of the toluene-isolubles in toluene at 25 deg.C is 14-20; and (iii) the gel content is 15-27 wt.%. The compsn. is impregnated with 4-12 wt.% n-pentane as a blowing agent to give expandable resin particles. The foamed molding is prepd. by foaming and molding the expandable resin particles and has a density of 0.014-0.05 g/cm<3> , an average cell size of 100-200μm, and a closed cell content of 70% or higher.