Production of core-sheath polymer particles containing voids, resulting product and use
US4594363A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 11, 1985 |
| Grant date | Jun 10, 1986 |
| Priority date | — |
| Expiry date | Jan 11, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S525/902
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Process for making core-sheath polymer particles containing voids, said particles useful for opacifying, comprising (A) emulsion polymerizing a core from a core monomer system comprised of at least one ethylenically unsaturated monomer containing acid functionality; (B) encapsulating said core with a hard sheath by emulsion polymerizing a sheath monomer system in the presence of said core, said sheath permitting penetration of fixed or permanent bases; (C) swelling at elevated temperature the resultant core-sheath polymer particles with fixed or permanent base so as to produce a dispersion of particles which, when dried, contain a microvoid which causes opacity in compositions in which they are contained, provided that either (1) said sheath comprises at least about 1% acid functional monomer or (2) said swelling takes place in the presence of solvent. Compositions comprising said core-sheath polymer particles are also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.