POLYMER PARTICLES

摘要

The present invention relates to a method of preparing an aqueous dispersion of polymer encapsulated particulate material, the method comprising: providing a dispersion of the particulate material in a continuous aqueous phase, the dispersion comprising ethylenically unsaturated monomer and a stabilizer for the particulate material; and polymerizing the ethylenically unsaturated monomer by non-living free radical polymerization to form polymer that encapsulates the particulate material, thereby providing the aqueous dispersion of polymer encapsulated particulate material; wherein polymerization of the ethylenically unsaturated monomer comprises: (a) polymerizing a monomer composition that includes ionizable ethylenically unsaturated monomer so as to form a base responsive water swellable non-living polymer layer that encapsulates the particulate material; and (b) polymerizing a monomer composition that includes non-ionizable ethylenically unsaturated monomer so as to form an extensible, water and base permeable non-living polymer layer that encapsulates the base responsive water swellable polymer layer.