Process for the preparation of concentrated dye-water compositions
US6750002B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 28, 2002 |
| Grant date | Jun 15, 2004 |
| Priority date | — |
| Expiry date | Jun 14, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C1/12
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
A process for preparing a concentrated photographic spectral sensitizing dye-water composition which comprises adding an anionic sensitizing dye to an aqueous medium in the substantial absence of organic solvent, and agitating the combined dye and aqueous medium, wherein the anionic dye forms a liquid-crystalline dye phase in the aqueous medium and the agitation is performed in the presence of a nonionic surfactant having an HLB of less than 12 and an aqueous solubility at 25° C. of greater than 10 ppm, which nonionic surfactant is in the aqueous medium at a level of from 10 to 1000 ppm. In a specific embodiment of the invention, where the viscosity (at 0.1 s−1 shear rate) of the dye-water composition in the absence of the nonionic surfactant would be greater than 100 cp and especially where such viscosity would be greater than 500 cp, the surfactant is preferably present at a level sufficient to substantially reduce air entrainment during agitation of the dye-water composition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.