| 摘要 |
A process for making void containing polymer particles comprising (A) emulsion polymerizing a core from a core monomer system comprising ethylenically unsaturated monomer containing acid functionality; (B) encapsulating said core with a sheath by emulsion polymerizing a sheath monomer system, comprising 0 to 10% by weight acid functional monomer, in the presence of said core, said sheath being permeable to fixed or permanent bases; (C) swelling, optionally in the presence of a solvent the polymer particles formed in (B) with fixed or permanent base so as to produce a dispersion of particles which, when dried, contain a single void which may cause opacity in compositions in which they are contained. <??>Compositions comprising said void containing polymer particles are also disclosed. |
