Calcium ion stable photographic color developing concentrate and method of manufacture
US6312877A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 21, 2000 |
| Grant date | Nov 6, 2001 |
| Priority date | — |
| Expiry date | Jul 21, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C5/267
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A homogeneous, ready to use, single-part color developing concentrate comprises a color developing agent in free base form, an antioxidant for the color developing agent, a buffering agent, and a water-miscible or water-soluble hydroxy-substituted, straight-chain organic solvent present in an a concentration such that the weight ratio of water to the organic solvent is from about 15:85 to about 50:50. In addition the concentrate includes a mixture of a specific polyaminopolyphosphonic acid and either a hydroxyalkylidene-diphosphonic acid or morpholinomethanediphosphonic acid (or salt thereof) for stability in the presence of calcium ions. This concentrate is prepared by mixing the components in a unique order for improved safety and manufacturability. It can be used to make a working strength processing solution, or it can be used as a replenishing composition with proper dilution to provide color images in photographic silver halide materials.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.