| 摘要 |
<p>A process for preparing a core-shell impact modifier emulsion having a rubbery core weight fraction exceeding 70% which comprises: (A) Polymerising in emulsion, a first mixture of monomers, comprising from 65% to 85% of a diolefin monomer and 15% to 35% of at least one vinyl aromatic monomer in the presence of an emulsifier and a free-radical initiator, until 60%-90% conversion of the monomers to polymer has been achieved; (B) continuing the polymerisation of the first mixture of monomers while adding a second mixture of monomers which mixture comprises at least one vinyl aromatic monomer or a C1-C4 alkyl methacrylate monomer; (C) continuing the polymerisation of the second mixture of monomers to at least 90% conversion to polymer has been achieved; and (D) adding a third mixture of monomers, which mixture comprises at least one C 1-C4 alkyl methacrylate monomer or at least one vinyl aromatic monomer, adding a free-radical initiator, and continuing the polymerisation until at least 95% conversion to polymer has been achieved. <??>The reaction temperature during steps (A) through (D) is in the range of from 60 DEG C to 70 DEG C.</p> |
