Rubber-modified polystyrene resin compositions and injection-molded articles.

摘要

Disclosed are a rubber-modified polystyrene resin composition which comprises a polystyrene resin serving as a matrix and soft component particles as dispersed therein, the composition fulfilling the following requirements (a) to (d): (a) the polystyrene resin as the matrix satisfies the following requirements: 150,000 </= Mw </= 500,000 wherein Mw is the weight average molecular weight, and 2 </= Bn(Mz) </= 20 wherein Bn(Mz) is the branch count or the number of branching points in the Z-average molecular weight (Mz), (b) the soft component particles in the composition have an average particle diameter (Dp) of 0.1 to 10 mu m, (c) the soft component particles in the composition have a swelling index in the range of 3 to 30, and (d) the proportion of the soft component particles in the composition is in the range of 5 to 30% by weight, as well as an injection-molded article formed from the composition.