US 4,139,387 A · Process for the production of direct-positive photographic images

Abstract

Positive images including color images are obtained by imagewise exposure and development of a material which comprises at least one light-sensitive silver halide emulsion layer which contains an unfogged direct-positive silver halide emulsion, when the development is carried out in the presence of a fogging agent of the formula ##STR1## wherein the symbols are defined as hereinafter. The fogging agent is preferably contained in a layer of the material and more preferably in the unfogged direct-positive silver halide emulsion layer. For the production of color instant images the material may also contain non-diffusible color providing compounds capable in their oxidized form of being split under alkaline photographic development conditions to release diffusible dyes.

Claims6

Dependent claims

A process for the production of direct-positive photographic images in which a photographic recording material having at least one light-sensitive silver halide emulsion layer which contains an unfogged direct-positive silver halide emulsion is exposed imagewise and developed in the presence of a fogging agent, wherein the improvement comprises the material contains from 0.1 to 100 mg per mol of silver halide of a fogging agent represented by the following general formula:

wherein
R.sup.1 and R.sup.4 are identical or different and represent hydrogen, a saturated or olefinically unsaturated aliphatic group, aryl, a heterocyclic group or acyl;
R.sup.2 and R.sup.3 are identical or different and represent hydrogen, a saturated or olefinically unsaturated aliphatic group, aryl or a heterocyclic group;
R.sup.5 denotes hydrogen, and/or
R.sup.1 together with R.sup.2 and/or
R.sup.3 together with R.sup.4 represent a methylidene group optionally substituted by alkyl, aryl, a heterocyclic group or by acyl, wherein two such substituents together with the carbon atom of the methylidene group may complete a carbocyclic or heterocyclic ring;
and/or
R.sup.1 together with R.sup.4 or R.sup.5 represent the group required for completing a 5-membered or 6-membered heterocyclic ring selected from the group consisting of 1,2,3,4-tetrazolidine-5-thione, hexahydro-1,2,4,5-tetrazine-3-thione, hexahydro-1,2,4-triazine-3-thione

5 more elements

A light-sensitive photographic material for the production of direct-positive images having at least one light-sensitive silver halide emulsion layer which contains an unfogged direct-positive silver halide emulsion and comprising a fogging agent, wherein the improvement comprises the material contains from 0.1 to 100 mg per mol of silver halide of a fogging agent represented by the following general formula:

##STR50## wherein R.sup.1 and R.sup.4 are identical or different and represent hydrogen, a saturated or olefinically unsaturated aliphatic group, aryl, a heterocyclic group or acyl;
R.sup.2 and R.sup.3 are identical or different and represent hydrogen, a saturated or olefinically unsaturated aliphatic group, aryl or a heterocyclic group;
R.sup.5 denotes hydrogen;
and/or
R.sup.1 together with R.sup.2 and/or
R.sup.3 together with R.sup.4 represent a methylidene group which may be substituted by alkyl, aryl, a heterocyclic group or by acyl, and two such substituents together with the carbon atom of the methylidene group may complete a carbocyclic or heterocyclic ring;
and/or
R.sup.1 together with R.sup.4 or R.sup.5 denote the group required for completing a 5-membered or 6-membered heterocyclic ring selected from the group consisting of 1,2,3,4-tetrazolidine-5-thione, hexahydro-1,2,4,5-tetrazine-3-thione, hexahydro-1,2,4-triazine-3-thione and 2,3,4,5-tetrahydro-1,2,4-triazine-3-thione.

5 more elements

Dependencies are inferred from the claim text.

Process for the production of direct-positive photographic images

Life of this patent

Process for the production of direct-positive photographic images

Life of this patent

Abstract

Claims6