Microprecipitation process for dispersing photographic filter dyes
US5624467A · kind A · utility
7Cited by
27References
30Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 20, 1991 |
| Grant date | Apr 29, 1997 |
| Priority date | — |
| Expiry date | Dec 20, 2011 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S516/01
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A process is provided for preparing microprecipitated dispersions of filter dyes by preparing a concentrated slurry in aqueous medium of a filter dye having ionizable acid sites on the dye molecule, adding sufficient aqueous hydroxide to dissolve the filter dye, acidifying the solution with a stoichiometric amount of acidic protons to reprotonate up to 100% of the total ionizable acid sites on the dye molecule and provide a microprecipitated dispersion of the filter dye that is insoluble in aqueous media at pH values less than 3 but soluble in aqueous media at pH greater than 10.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.