Process for the precipitation of stable colloidal dispersions of base degradable components of photographic systems in the absence of polymeric steric stabilizers
US4933270A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 26, 1988 |
| Grant date | Jun 12, 1990 |
| Priority date | — |
| Expiry date | Sep 26, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/158
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The invention provides a method of forming a dispersion of base degradable hydrophobic component for a photographic system. The invention is accomplished by mixing the component, solvent, and surfactant, at an elevated temperature if necessary, metering the mixture of solvent, surfactant, and hydrophobic component to an excess of water with agitation so as to precipitate from the water solvent solution small particles of the hydrophobic component. The small particles then form a stable dispersion, after washing by dialysis or diafiltration, that will not agglomerate during storage prior to use. The preferred photographic component for use in the system of the invention is an ester terminated photographic coupler that would decompose if subjected to the high pH treatment of prior art procedures.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.