Claims
- 1. A process for preparing emulsion polymer particles comprising:
- (a) providing an aqueous emulsion of
- (i) multi-stage emulsion polymer, comprising a core stage polymer and a shell stage polymer,
- wherein the core stage polymer comprises, as polymerized units, from 5 to 100 percent by weight, based on the weight of the core stage polymer, of hydrophilic monoethylenically unsaturated monomer, and from 0 to 95 percent by weight, based on the weight of the core stage polymer, of at least one nonionic monoethylenically unsaturated monomer; and
- wherein the shell stage polymer comprises, as polymerized units, at least 50 percent by weight of nonionic monoethylenically unsaturated monomer;
- (ii) monomer at a level of at least 0.5 percent by weight based on the weight of the multi-stage emulsion polymer; and
- (iii) swelling agent under conditions wherein there is no substantial polymerization of the monomer; and
- (b) reducing the level of monomer by at least fifty percent.
- 2. The process of claim 1 wherein the monomer at a level of at least 0.5 percent by weight based on the weight of the multi-stage emulsion polymer is one or more of the monomers used to prepare the multi-stage emulsion polymer.
- 3. The process of claim 1 wherein the monomer at a level of at least 0.5 percent by weight based on the weight of the multi-stage emulsion polymer is nonionic monomer.
- 4. The process of claim 1 wherein the swelling agent is selected from volatile base, fixed base, and combinations thereof.
- 5. The process of claim 1 wherein the level of monomer is reduced to less than 10,000 ppm based on polymer solids by polymerizing said monomer.
Parent Case Info
This application claims benefit of Provisional Application 60,064,513 filed Nov. 5, 1997.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
WO 9511265 |
Apr 1995 |
WOX |