Rubber-containing styrenic resin and process for producing the same

Abstract

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  (1) 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.

Dependencies are inferred from the claim text.