The rubber-containing styrenic resin of the present invention comprises a styrenic resin matrix and a rubber component dispersed in particles. In the resin, the graft ratio of a styrenic monomer relative to the rubber component is not less than 1, the particle size of the dispersed rubber component is 0.1 to 3 µm, and the following equation (1) is satisfied:Mn = aT + b wherein Mn is the number average molecular weight of the matrix resin; T is the conversion of the styrenic monomer; a is a constant greater than 0; and b is a constant of 0 or greater.
The rubber component may be a butadiene-series rubber. The particle-size distribution of the dispersed rubber component may have, for example, two peaks. Such styrenic resin can be produced by, in the presence of a rubber component, polymerizing at least a styrenic monomer at a graft ratio of not less than 1 under such conditions that the relationship between the conversion T of the styrenic monomer and the number average molecular weight Mn of the polymer can be approximated by a linear equation. According to the present invention, the morphology and the particle size of rubber particles dispersed in a styrenic resin are controllable.
本发明的含橡胶
苯乙烯树脂包括
苯乙烯树脂基体和分散在颗粒中的橡胶组分。在该
树脂中,
苯乙烯单体相对于橡胶组分的接枝比不小于 1,分散橡胶组分的粒径为 0.1 至 3 µm,并满足下式(1):Mn = aT + b 其中,Mn 为基体
树脂的平均分子量;T 为
苯乙烯单体的转化率;a 为大于 0 的常数;b 为 0 或大于 0 的常数。
橡胶成分可以是
丁二烯系列橡胶。分散橡胶成分的粒度分布可以有两个峰值。这种
苯乙烯树脂可通过在橡胶组分存在的条件下,以不小于 1 的接枝比聚合至少一种
苯乙烯单体,使
苯乙烯单体的转化率 T 与聚合物的数均分子量 Mn 之间的关系可以用线性方程近似表示。根据本发明,分散在
苯乙烯树脂中的橡胶颗粒的形态和粒径是可控的。