| abstract |
A thermoplastic resin is produced by polymerising a monomer mixture comprising an unsaturated nitrile monomer and an alkenyl aromatic monomer in the presence of a rubbery polymer latex, the polymerisation taking place in at least two steps. In the first step, the monomer mixture has an unsaturated nitrile monomer content of from 0 to 20% by weight and is from 30 to 70% by weight of the whole monomer mixture. In the second and subsequent steps, the remaining monomer mixture has an unsaturated nitrile monomer content of from 35 to 90% by weight. The unsaturated nitrile monomer content in the part of the polymer formed by polymerisation of the monomer mixture is from 28 to 38% by weight. The thermoplastic resin can have high chemical resistance, excellent impact resistance and excellent processability. |