| 摘要 |
The present invention is an acrylic polymer particle which is consistently and substantially spherical in shape and which has a mean diameter that can be predetermined from about 30 microns in diameter to about 5 microns or less. Polyacrylonitrile is synthesized in an aqueous dispersion polymerization with a ionic monomer or "surfmer" to attain a narrow particle size distribution with a mean diameter as low as approximately 3±1.5 microns which is characteristic of an emulsion polymerization. The polymer comprises the ionic monomer and, optionally, a neutral comonomer. The mean particle size is dependent on the concentration of the ionic monomer present, the particular ionic monomer or monomers selected, and the counterion associated with the ionic monomers, the persulfate initiator, and the bisulfite activator. The counterions, often sodium ions, can be removed from the polymer particles by ion exchange with quaternary ammonium compounds.
|
