Mitsui Toatsu Chemicals, Incorporated

Kouzou Ichikawa

Mune Iwamoto

Toshihiko Ando

Masato Takaku

Masahiro Kaneko

Akihiko Nakajima

A rubber modified styrenic resin composition which can be obtained by dispersing rubber-like polymer particles in a homopolymer or a copolymer of a styrenic monomer. The rubber modified styrenic resin composition has: (a) a volume-average particle size of the rubber-like polymer particles is in the range of from 0.2 to 0.8 .mu.m, (b) a particle size distribution curve on the basis of the volume of the rubber-like polymer particles has one peak, (c) a ratio of a 5% value to a 95% value of the cumulative distribution of the particle size on the basis of the volume of the rubber-like polymer particles is in the range of from 3 to 45. The rubber-like polymer particles comprise (i) a styrene-butadiene block copolymer (I), and (ii)(1) a styrene-butadiene block copolymer (II), (2) a polybutadiene (III), or (3) a styrene-butadiene block copolymer (IV) and polybutadiene (V), wherein (I) contains 25-50 % styrene, (II) and (IV) contain 5-20% styrene, the weight ratio of: (I)/(II), (I)/(III) and (I)/(IV) is from 95/5 to 40/60 and {(I)+(IV)}/(V) is from 99/1 to 70/30 and (I) to (V) are of specified styrene solution viscosity.

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Hadano, Japan

Kouzou Ichikawa