Polybutadiene rubber and impact-resistant aromatic vinyl resin compositions

A process for preparing polybutadiene rubber wherein a molecular weight distribution curve of the rubber as determined by gel permeation chromatography (GPC) has 2 peaks attributable to a high molecular weight component and a low molecular weight component, a peak top molecular weight of the high molecular weight component and a peak top molecular weight of the low molecular weight component fall within ranges of from 100,000 to 1,500,000 and from 10,000 to 50,000, respectively, a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), Mw/Mn, falls within a range of from 4.5 to 14.5, and the content of a cis-1,4 structure is at least 80 wt. %, the process comprising the step of blending high molecular weight polybutadiene, in which the peak top molecular weight as determined by GPC falls within a range of from 100,000 to 1,500,000, with low molecular weight polybutadiene, in which the peak top molecular weight falls within a range of from 10,000 to 50,000, in a state of solutions.

A modifier for resins, comprising, as an active ingredient, polybutadiene rubber wherein a molecular weight distribution curve of the rubber as determined by gel permeation chromatography (GPC) has 2 peaks attributable to a high molecular weight component and a low molecular weight component, a peak top molecular weight of the high molecular weight component and a peak top molecular weight of the low molecular weight component fall within ranges of from 100,000 to 1,500,000 and from 10,000 to 50,000, respectively, a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), Mw/Mn, falls within a range of from 4.5 to 14.5, and the content of a cis-1,4 structure is at least 80 wt. %.

A process for preparing a high-impact aromatic vinyl resin composition, which comprises radical-polymerizing 99 to 60 wt. % of (B) an aromatic vinyl monomer or a mixture of the aromatic vinyl monomer and a monomer copolymerizable therewith in the presence of 1 to 40 wt. % of (A) polybutadiene rubber wherein a molecular weight distribution curve of the rubber as determined by gel permeation chromatography (GPC) has 2 peaks attributable to a high molecular weight component and a low molecular weight component, a peak top molecular weight of the high molecular weight component and a peak top molecular weight of the low molecular weight component fall within ranges of from 100,000 to 1,500,000 and from 10,000 to 50,000, respectively, a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), Mw/Mn, falls within a range of from 4.5 to.14.5, and the content of a cis-1,4 structure is at least 80 wt. %.