Patent ID: 7906576

Claim:
A mass-continuous process for the preparation of a rubber-reinforced vinyl aromatic (co)polymer comprising: a. preparing a solution comprising: from 3 to 20% by weight of a rubber having a solubility parameter (δ 1 MPa 1/2 ), selected from the group consisting of homopolymers and copolymers of 1,3-alkadienes containing 40-100% by weight of 1,3-alkadiene monomer and 0-60% by weight of one or more mono-ethylenically unsaturated monomers, from 0.05 to 8.0% by weight of a rubber having a solubility parameter (δ 2 MPa 1/2 ) selected from the group consisting of homopolymers and copolymers of olefins or 1,3-alkadienes and at least one vinyl aromatic monomer; b. polymerizing the solution at a temperature ranging from 50 to 250° C. optionally in the presence of polymerization initiators and/or chain transfer agents to obtain the rubber-reinforced vinyl aromatic (co)polymer with a strictly bimodal morphology; and c. recovering the rubber-reinforced vinyl aromatic (co)polymer thus obtained; wherein the rubber of solubility parameter δ 1 and the rubber of solubility parameter δ 2 are incompatible, δ 1 −δ 2 ≧0.5, and the recovered rubber-reinforced vinyl aromatic (co)polymer consists of: from 55 to 90% by weight of rigid polymeric matrix and from 10 to 45% by weight of grafted and occluded particles having a strictly bimodal morphology, consisting of: from 60 to 99% by weight of particles with a capsule or “core-shell” morphology and from 1 to 40% by weight of particles with a “salami” morphology.