| 摘要 |
Disclosed is a polymer encapsulated particulate material comprising: a particulate material, a water swellable polymer layer that encapsulates the particulate material capable of changing in volume in response to the presence or absence of water; and an extendable water permeable polymer layer that encapsulates the water swellable polymer layer and stretches to accommodate the volume changes of said water swellable polymer layer. Also disclosed is a method of producing an aqueous dispersion of the polymer encapsulated particulate material comprising: providing a dispersion of the particulate material in a continuous aqueous phase, the dispersion comprising ethylenically unsaturated monomer and a stabiliser; and (a) polymerising a monomer composition that includes ionisable ethylenically unsaturated monomer so as to form the base responsive water swellable non-living polymer layer that encapsulates the particulate material; and (b) polymerising a monomer composition that includes non-ionisable ethylenically unsaturated monomer so as to form the extensible, water and base permeable non-living polymer layer that encapsulates the base responsive water swellable polymer layer. Examples of the ionisable ethylenically unsaturated monomer used to form the water swellable polymer layer are: Methyl methacrylate (MMA), butyl acrylate (BA) and methacrylic acid (MA), and/or acrylic acid (AA). Examples of the non-ionisable ethylenically unsaturated monomer used to form the extendable water permeable polymer layer are: Styrene, methyl methacrylate, and butyl acrylate. |
