Heat-resistant high-impact polystyrene composition

A heat-resistant, high-impact polystyrene composition comprising (A)-(D) in parts by weight:

• (A) 100 parts by weight of high-impact polystyrene,
• (B) from 1.5 to 5 parts by weight of glass fibers,
• (C) from 2.5 to 10 parts by weight of a styrene-butadiene-styrene copolymer, and
• (D) from 0.05 to 5 parts by weight of a metal salt of a higher fatty acid,
• the high-impact polystyrene (A) having a polybutadiene content of from 4.5 to 8.0% by weight based on the weight of the high-impact polystyrene and an average rubber particle diameter of from 0.5 to 2.0 .mu.m and containing no plasticizer;
• the glass fibers (B) having an average fiber length of from 0.5 to 2 mm and an average aspect ratio of 20 or more and having undergone surface treatment with a silane coupling agent;
• and
• the styrene-butadiene-styrene copolymer (C) having a butadiene unit content of from 40 to 80% by weight based on the weight of the styrene-butadiene-styrene copolymer.