Preparation of tabular emulsion grains rich in chloride
US5601969A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 10, 1991 |
| Grant date | Feb 11, 1997 |
| Priority date | — |
| Expiry date | Oct 10, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C2200/44
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method 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 the tabular grains, and wherein the 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. The method comprises PA1 preparing a dispersion medium containing a gelatino-peptizer, and a compound ##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, R is hydrogen or a substituent as defined for ring Z; n is 1 or 0, and Q represents carbon in which case n=1, or Q represents nitrogen, in which latter case n =0; in a concentration ranging from 10.sup.-4 to 10.sup.-2 molar. The pH of the medium is adjusted to between 5.0 and 9.0 and to a pCl between 1.0 and 2.0 by means of a chloride ions providing salt; PA1 performing a silver halide precipitation comprising at least one double jet step by introducing in the disper…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.