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; (b) adding an effective amount of one or more polymerization inhibitors or reducing agents to substantially stop any polymerization; (c) providing monomer at a level of at least 0.5 percent by weight based on the weight of the multi-stage emulsion polymer; (d) adding swelling agent; and (e) reducing the level of monomer by at least fifty percent.
- 2. The process of claim 1 wherein the one or more polymerization inhibitors or reducing agents are added in an amount of from 25 to 5,000 ppm based on polymer solids.
- 3. The process of claim 1 or claim 2 wherein the one or more polymerization inhibitors are selected from the group consisting of N,N-diethylhydroxylamine, N-nitrosodiphenylamine, 2,4-dinitrophenylhydrazine, p-phenylenediamine, phenothiazine, alloocimene, triethyl phosphite, 4-nitrosophenol, 2-nitrophenol, p-aminophenol, 4-hydroxy TEMPO, hydroquinone, p-methoxyhydroquinone, tert-butyl-p-hydroquinone, 2,5-di-tert-butyl-p-hydroquinone, 1,4-naphthalenediol, 4-tert butyl catechol, copper sulfate, copper nitrate, cresol and phenol.
- 4. 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.
- 5. 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.
- 6. The process of claim 1 wherein the swelling agent is selected from volatile base, fixed base, and combinations thereof.
- 7. 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 is a divisional application of patent application Ser. No. 08/974,763, filed Nov. 20, 1997, now U.S. Pat. No. 6,020,435 and claims benefit to U.S. Provisional application Ser. No. 60/064,513 filed Nov. 5, 1997.
US Referenced Citations (7)
Foreign Referenced Citations (1)
Number |
Date |
Country |
WO 9511265 |
Apr 1995 |
WO |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/064513 |
Nov 1997 |
US |