Patent ID: 6383725
Filing Date: 2002-05-07
Classification: G03C,Y10S

Abstract:
An emulsion comprising a substantially light-insensitive organic silver salt, a photosensitive silver halide in catalytic association with said substantially light-insensitive organic silver salt, a binder, and a polyhalide compound selected from the group consisting of quaternary ammonium polyhalides, quaternary phosphonium polyhalides and ternary sulphonium polyhalides, wherein said polyhalide compound satisfies a test having the following steps:(i) preparing a silver behenate dispersion in deionized water by rapidly mixing with anionic sulfonate dispersion agents to produce a predispersion containing 20% by weight of silver behenate, homogenizing to a finely divided and stable dispersion, and then adjusting the pH to about 6.5; (ii) adding to 1.5 g of the silver behenate dispersion of (i) with stirring: 1 g of a 30% by weight dispersion of a latex-copolymer, 0.1 g of a 11% by weight solution of saponin in a mixture of deionized water and methanol and an aqueous solution of said polyhalide compound in a quantity corresponding to a concentration of 8 mol % with respect to the silver behenate present to produce silver behenate/silver halide dispersion; (iii) coating said silver behenate/silver halide dispersion of (ii) on a subbed polyethylene terephthalate support, drying said coating, then overcoating with a 2.44% by weight aqueous solution of 3-(3,4-dihydroxyphenyl)-propionic acid and drying to produce a test thermographic material; (iv) exposing said test thermographic material of (iii) to ultraviolet light in an Agfa-Gevaertâ„¢ DL2000 exposure apparatus and heating on a metal block for 10 s at 95Â° C.; and (v) measuring the optical density of the exposed and thermally developed test material with a densitometer with a visible filter, wherein the developed test thermographic material has an optical density of less than 0.3.