Polymeric particles and their preparation
US4985469A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 7, 1988 |
| Grant date | Jan 15, 1991 |
| Priority date | — |
| Expiry date | Dec 7, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S525/902
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Polymer particles or beads for use as opacifiers in paints are described in which a core is provided with a hard sheath and the particle has one or more voids produced by reaction with a nonvolatile permanent or fixed base. The sheath is a copolymer of an ethylenically unsaturated aliphatic monomer free of acid groups and at least 2 percent by weight of a soft ester-containing monomer and optionally styrene in an amount of up to 25 mole percent. The core is formed from an ethylenically unsaturated monomer with acid functionality. The sheath polymer has a glass transition temperature of at least 40.degree. C. The particles have a size of up to 40000 nanometers before swelling the core by some 150 to 2000 percent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.