GB656942A - Improvements in sensitive photographic emulsions - Google Patents

Abstract

656,942. Photographic emulsions. KODAK, Ltd. Jan. 13, 1949, No. 1021. Convention date, Jan. 13, 1948. [Class 98 (ii)] A light-sensitive photographic emulsion comprises a cellulose carboxylic ester silver halide emulsion sensitized with at least one substantially colourless substantially non-surface-active quaternary salt of the benzthiazole or benzselenazole series. The emulsion may also contain a sensitizing dye such as a cyanine, merocyanine, hemicyanine, hemioxonol, or styryl dye. The cellulose carboxylic ester may be a hydrolysed cellulose carboxylic ester containing from 19 to 33 per cent by weight of acyl groups, and may be hydrolysed cellulose acetate or acetate-propionate. The quaternary salt may have the formula wherein D represents an o-arylene group of the benzene series containing from 6 to 8 carbon atoms and which is devoid of nitro groups, Q represents S or Se, R represents a primary alkyl, alkenyl, hydroxyalkyl, or alkoxyalkyl group containing from 1 to 4 C atoms, R 1 is H, methyl, ethyl, an alkylmercapto group containing from 1 to 4 C atoms, an arylmercapto group containing from 6 to 8 C atoms and which is devoid of nitro groups, a primary amino group, an alkylamino group containing 1 to 4 C atoms, a dialkylamino group containing from 2 to 4 C atoms, or an arylamino or aralkylamino group containing from 6 to 8 carbon atoms and which is devoid of nitro groups, and X represents an anion. Quaternary salts specified are benzthiazole ethiodide and metho-p-toluenesulphonate, 2 - methylbenzthiazole metho - p - toluenesulphonate, etho - p - toluenesulphonate, alliodide, or n-butiodide, 5-chloro-2-methylbenzthiazole etho - p - toluenesulphonate, 2 - methylmercaptobenzthiazole metho -p -toluene - sulphonate, 2 - phenylmercaptobenzthiazole ethiodide, 2 - anilinobenzthiazole ethiodide, 2 - methylbenzselenazole ethiodide, 5 - chloro - 2 - methylbenzselenazole ethiodide, and 2-mercaptobenzthiazole - # - hydroxyethiodide. One or more of the quaternary salts may be used, and may be added to the finished emulsion just prior to coating in water or methyl or ethyl alcohol or a mixture thereof. A table is given showing the speed and contrast values for white, minus-blue, and blue-light for a hydrolysed cellulose acetate silver chlorbromiodide emulsion in which the cellulose acetate contains from 23 to 24 per cent by weight of acetyl groups with and without quaternary salts, the emulsion in some cases also containing 2 : 3<SP>1</SP>- diethyl - 41 - methyloxathiazolocarbocyanine iodide. Specifications 450,958, 479,239, 513,170, 515,145, 517,769, [Group IV], 522,997, 533,238, [Group IV], 557,178, and 560,082 are referred to.