STABILISATION OF PHOTOGRAPHIC SILVER HALIDE MATERIALS

1,218,444. Stabilizing exposed photographic silver halide materials. EASTMAN KODAK CO. Jan. 26, 1968 [Jan. 27, 1967], No. 4271/68. Heading G2C. A light-sensitive heat-stabilizable photographic silver halide material comprises a silver halide emulsion layer and a contiguous layer containing per mole of silver halide at least one mole of a stabilizer precursor, which is a sulphur-containing organic compound which breaks down at elevated temperatures to form a compound which combines with unexposed silver halide to form a light-stable silver mercaptide, and at least one quarter mole of an activator precursor which is a compound which breaks down at temperatures above about 90‹C. to form an alkaline compound, which aids in the breakdown of the stabilizer precursor. After exposure and development, the materials can be stabilized by heating, the stabilization being more quickly effected than materials in which an activator precursor is absent. Stabilizer precursors specified include those specified in Specification 1,113, 603, e. g. 3-S-thiuronium propane sulphonate and 2-hydroxyethyl isothiuronium trichloroacetate, and activator precursors include guanidinium salts, e. g. the trichloroacetate and oxalate, quaternary ammonium malonates, e. g. piperidinium malonate, amine malonates, amino acids, heat cleavable hydrazides oxazolidone and sodium trichloroacetate. The materials may be developed by applying a thin layer of developer and then be stabilized by heat or a developing agent may be incorporated in the material which is then heat-developed and heatstabilized.