Method for the preparation of tabular emulsion grains rich in chloride
US5286621A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 26, 1992 |
| Grant date | Feb 15, 1994 |
| Priority date | — |
| Expiry date | Aug 26, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C2200/44
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method is disclosed for the preparation of silver halide tabular emulsion grains, containing at least 75% chloride, wherein at least 50% of the total projected area of all the grains is provided by said tabular grains, and wherein said tabular grains exhibit an average aspect ratio of at least 5:1, an average thickness not greater than 0.5 micron and an average diameter of at least 0.6 micron, by a process comprising the following steps: PA1 (1) preparing a dispersion medium containing a gelatino-peptizer, and performing the precipitation of the silver halide grains under the following conditions: PA2 (a) the chloride ion concentration in the dispersion medium is lower than 0.15 molar at the start of the precipitation and remains lower than 0.15 molar during the whole precipitation, and pH is maintained between 5.0 and 9.0; PA2 (b) the precipitation is performed in the presence of a crystal habit modifyer according to general formula Ia or Ib: ##STR1## wherein Z represents the atoms necessary to form a fused on aromatic carbocyclic or heterocyclic, unsubstituted or substituted ring, e.g. substituted with alkyl, alkenyl, aryl, alkoxy, hydroxy, mercapto, carboxy, amino or halogen, …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.