High chloride tabular grain emulsions and processes for their preparation
US5320938A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 25, 1993 |
| Grant date | Jun 14, 1994 |
| Priority date | — |
| Expiry date | Aug 25, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C2200/59
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Silver halide emulsions are disclosed in which at least 50 percent of total grain projected area is accounted for by tabular grains (1) bounded by {100} major faces having adjacent edge ratios of less than 10, (2) each having an aspect ratio of at least 2, and (3) internally at their nucleation site containing iodide and at least 50 mole percent chloride. The emulsions are prepared by a process comprised of the steps of (a) introducing silver and halide salts into a dispersing medium so that nucleation of the tabular grains occurs in the presence of iodide with chloride accounting for at least 50 mole percent of the halide present in the dispersing medium and the pCl of the dispersing medium being maintained in the range of from 0.5 to 3.5 and (b) following nucleation completing grain growth under conditions that maintain the {100} major faces of the tabular grains.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.