Process for preparation of quinacridone pigments using moderately concentrated acid
US4247695A · kind A · utility
6Cited by
10References
17Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Feb 26, 1979 |
| Grant date | Jan 27, 1981 |
| Priority date | — |
| Expiry date | Feb 26, 1999 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09B67/0017
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A process for preparing beta or gamma crystals of linear quinacridone, substituted quinacridone or solid solutions thereof by contacting premilled quinacridone with 45-60% by weight sulfuric acid and 0-10% by weight of a surfactant based on the quinacridone at a weight ratio of acid to quinacridone of 3:1-6:1 to form a slurry, agitating said slurry for a period of time at 45.degree.-75.degree. C., adding water to form a dilute slurry, agitating said dilute slurry for a period of time at 75.degree.-95.degree. C. and separating quinacridone from the liquid of the dilute slurry.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.