Kaolin clay pigment for paper coating and method for producing same
US6402826B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 30, 1999 |
| Grant date | Jun 11, 2002 |
| Priority date | — |
| Expiry date | Nov 30, 2019 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/80
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A kaolin clay pigment comprises a coarse kaolin clay or a blend of a coarse kaolin clay with a fine kaolin clay. The coarse kaolin clay is a delaminated and defined pigment product with an overall shape factor greater than about 12. If the coarse kaolin clay is fluid at about 65% to about 75% solids, then it is used by itself as the kaolin pigment. If it is not fluid, it is blended with a fine kaolin clay in amounts ranging from about 0.1% to about 30.0% by weight of the blend. The coarse kaolin clay fraction has a Hinckley Crystallinity Index greater than about 0.6 and the fine kaolin clay has a Hinckley Crystallinity Index less than about 0.5. The pigment has a G.E. brightness of about 90.5 and a particle size distribution such that at least about 90% by weight of the particles has an e.s.d. less than about 2 &mgr;m and about 30% by weight of the particles has an e.s.d. less than about 0.25 microns. At about 65% to about 75% solids, the Hercules viscosity is greater than 250 rpm at about 18 dynes and when used in a coating formulation, exhibits improved sheet brightness, sheet gloss, sheet opacity and print gloss.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.