RESIN COMPOSITION AND FOAMED MOLDING THEREOF

PROBLEM TO BE SOLVED: To provide a foamed container resin (composition) good having a heat resistance and flowability, causing less defectives in foam molding and, simultaneously, suitable for use in microwave ovens, and a foamed molding thereof, particularly a foamed container thereof. SOLUTION: Desired resin compositions comprise (I) 100 pts.wt. styrenic copolymer resin obtained by polymerizing 80-99.9 wt.% styrenic monomer and 20-0.1 wt.% methacrylic acid monomer and (II) 0-10 pts.wt. butadiene based rubber containing not less than 30 wt.% butadiene rubber. The ratio (J0 /η0 ) of equilibrium recovery compliance (η0 ) to melt viscosity (J0 ) at the temperature of the resin composition of 200 deg.C is 3.0×10 -15.0×10 cm /dyn.poise. It is preferred that the styrenic copolymer resin (I) has a weight average molecular weight(Mw) of 200,000-400,000 and a ratio (Ma/Mw) of the z average molecular weight (Mz) to the weight average molecular weight(Mw) of 2.0-2.4 and the butadiene based rubber (II) is a methyl methacrylate/butadiene/styrene rubber (MBS).