Method for forming high contrast photographic image
US4377634A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 1980 |
| Grant date | Mar 22, 1983 |
| Priority date | — |
| Expiry date | Mar 11, 2000 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07D285/125
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A method for forming a high contrast negative photographic image, which comprises imagewise exposing a photographic material comprising a support having thereon at least one photographic silver halide emulsion layer with the photographic silver halide emulsion layer or at least one hydrophilic colloid layer of the photographic material containing a compound of the general formula (I) EQU R.sup.1 --NHNHCO--R.sup.2 (I) wherein R.sup.1 represents an aryl group, and R.sup.2 represents a hydrogen atom, a phenyl group, or an unsubstituted alkyl group containing 1 to 3 carbon atoms, and then developing the imagewise exposed material in the presence of a hydroquinone compound of the general formula (II) ##STR1## wherein R.sup.3, R.sup.4, R.sup.5 and R.sup.6, which may be the same or different, each represents a hydrogen atom, a sulfo group, an alkyl group, an aryl group, an aralkyl group, a heterocyclic group, or a group of the formula --O--R.sup.7 or --S--R.sup.7 where R.sup.7 represents an alkyl group, an aryl group, an aralkyl group, or a heterocyclic group with at least one of R.sup.3, R.sup.4, R.sup.5 and R.sup.6 representing a group other than a hydrogen atom or a sulfo group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.