Light-sensitive emulsion having (100) tabular grains rich in silver chloride and method for preparing said grains
US6136524A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 24, 1999 |
| Grant date | Oct 24, 2000 |
| Priority date | — |
| Expiry date | Feb 24, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C2200/01
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A light-sensitive silver halide photographic emulsion has been described, said emulsion comprising a colloidally stabilizing binder and {100} tabular silver halide grains containing at least 50 mole % of silver chloride, wherein at least 70% by number of all grains is provided by said tabular grains, exhibiting an average aspect ratio of at least 5 and an average equivalent circular grain diameter of at least 0.3 .mu.m, wherein said tabular grains have an average thickness of less than 0.25 .mu.m for at least 75% by number of all tabular grains. In order to prepare said emulsion a method has been disclosed comprising performing at least three distinct precipitation steps in an aqueous medium in a reaction vessel, followed by desalting by means of washing after flocculation or by means of ultrafiltration, wherein said three distinct precipitation steps consist of a nucleation step followed by a first and a second growth step, said method being further characterized by introducing in the said reaction vessel, after the first growth step, of a block-copolymer according to the formula (I) as described in the detailed description and in the claims.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.