Thermoplastic molding materials and their preparation

摘要

A thermoplastic molding material contains, in each case based on the molding material comprising A+B, A from 80 to 60% by weight of a hard matrix composed of polystyrene and B from 20 to 40% by weight of a soft phase which is obtainable by polymerization of styrene in the presence of a linear styrene/butadienne block copolymer which has an ill defined transition, contains from 35 to 45% by weight of styrene and from 65 to 55% by weight of butadiene and has a block polystyrene content of from 25 to 35% by weight, the soft phase being uniformly distributed in the hard matrix and having a particle diameter of less than 0.8 mu m. The typical features of the said molding material are that the median particle diameter d50 (volume average of the soft phase B is from 0.25 to 0.38 mu m, the width of the particle size distribution, (d9514 d5), is from 0.2 to 0.6 mu m, the d60 value is from 0.26 to 0.40 mu m and the d90 value is from 0.40 to 0.75.