Tabular acicular gypsum and method of filling paper
US4801355A · kind A · utility
5Cited by
14References
11Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jan 16, 1987 |
| Grant date | Jan 31, 1989 |
| Priority date | — |
| Expiry date | Jan 16, 2007 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2004/61
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A tabular variety of acicular gypsum crystal filler is prepared by hydrating calcium sulfate dihydrate particles in a seeded continuously stirred reactor at a low level of super-saturation to obtain crystals having an aspect ratio of about 100:10:1 and average length in the longest dimension of about 100-450 micrometers. For the manufacture of paper, the obtained tabular crystal slurry may be directly added to the paper pulp before web formation to obtain a filled paper having high filler retention.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.