Process for the preparation of high chloride emulsions containing iodide
US6265145A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 30, 1999 |
| Grant date | Jul 24, 2001 |
| Priority date | — |
| Expiry date | Dec 30, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C2200/01
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A process for the preparation of a radiation-sensitive silver halide emulsion comprised of high chloride cubical silver halide grains containing from 0.05 to 3 mole percent iodide, based on total silver, where the iodide is incorporated in the grains in a controlled, non-uniform distribution forming a core containing at least 50 percent of total silver, an iodide free surface shell having a thickness of greater than 50 .ANG., and a sub-surface shell that contains a maximum iodide concentration is disclosed, the process comprising: (a) providing in a stirred reaction vessel a dispersing medium and host high chloride silver halide cubical grains comprising a speed enhancing amount of iodide, and (b) precipitating silver halide onto the host grains by introducing at least a silver salt solution into the dispersing medium at a rate such that the normalized molar addition rate, R.sub.n, is above 3.0.times.10.sup.-2 min.sup.-1, R.sub.n satisfying the formula: EQU R.sub.n =[Q.sub.f.times.C.sub.f ]/M where Q.sub.f is the volumetric rate of addition, in L/min, of silver salt solution into the reaction vessel; C.sub.f is the concentration, in moles/L, of the silver salt solution; and M is to…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.