Aggregated composite mineral pigments
US5236989A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 29, 1991 |
| Grant date | Aug 17, 1993 |
| Priority date | — |
| Expiry date | Aug 29, 2011 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/80
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A process for forming chemically aggregated composite porous bulking pigments for use in paper filling and coating formulations. An aqueous slurry is formed of feed mineral particles selected from one or more members of the group consisting of kaolin, calcium carbonate, titanium dioxide, gypsum, and mica. A high molecular weight carboxyl-containing polymer or copolymer is added to the slurry to flocculate the mineral particles. An excess of calcium ion is added to the flocced slurry to precipitate the calcium salt of the carboxyl-containing polymer in situ on the feed mineral flocs, and thereby form aggregates of feed mineral particles interconnected by the calcium salt and having a bulk, porous, floc structure. Gaseous carbon dioxide is added to the slurry, and reacts with remaining calcium ion to precipitate calcium carbonate onto the polymeric carboxyl calcium salt. This forms additional light scattering voids or pores and strengthens the connections among the flocced feed particles. The resultant composite aggregates are recovered and dried, as product. The composite aggregate products are also disclosed and claimed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.