GB767703A - Improvements in direct positive photographic processes - Google Patents

Abstract

767,703. Direct positive photographic images. KODAK, Ltd. Aug. 3, 1954 [Aug. 3, 1953], No. 22509/54. Drawings to Specification. Class 98(2) A direct positive photographic image is produced by developing an exposed silver halide emulsion layer of the "internal" latent image type as defined in Specification 645,877 in the presence of a hydrazine compound of the general formula H 2 N.NHD-(CH 2 )n-NHSO 2 R (wherein D is a divalent mononuclear arylene group of the benzene series, n is 0 or 1 to 4, and R is an alkyl group) in a developing solution containing one of the compounds 3-methyl- 2-#-phenethyl-isoquinolinium bromide, 2- benzyl-3-methyl-isoquinolinium bromide, 1- #-phenethyl-#-picolinium bromide, 1-#- phenethyl-quinolinium bromide, and 1-#- phenethyl-lepidinium bromide. The following compounds are not effective in accelerating development :-2-methylbenzselenazole methiodide 3-methyl benztriazolium p - toluenesulphonate, 2 : 3 - dimethyl-6-aminobenzthiazole perchlorate, 1- benzyl-a-, -#- and-γ-picolinium bromide, 1- # phenethyl-γ-picolinium bromide, 1-#- phenethyl-quinaldinium bromide, ethylenebis-(pyridinium perchlorate), #-phenethyla - picolinium bromide, p-tert. - butyl - phenoxyethoxyethyl - pyridinium per chlorate, and N:N<SP>1</SP> - ethylenedioxymethylpyridinium perchlorate. The hydrazine compound may be incorporated in the developing solution or in the emulsion, a number of such compounds being specified. The developing agent may be N- methyl - p - aminophenol sulphate, hydroquinone, catechol. 2-methylhydroquinone,; 2 - chlorohydroquinone, p - aminophenol, pyrogallol, or a 3-pyrazolidone developing agent, a number of which are specified. A mixture of hydroquinone with N-methyl-p-, aminophenol or a 3-pyrazolidone may be used. In Example 1, an emulsion made as described in Example 1 of Specification 635,841 is exposed and developed in a solution of N-methyl-p-aminophenol sulphate, hydroquinpne, p -(#-methylsulphonamidoethyl) - phenylhydrazine hydrochloride, sodium sulphite, trisodium phosphate, diglycolic acid, 5-methylbenztriazole, sodium hydroxide, and 3-methyl-2-#-phenethylisoquinolinium bromide. Similar, developer compositions are used in Examples 2 to 5, Examples 2,4, and 5 using as developing agents a mixture of hydroquinone and 1- phenyl - 3 - pyrazolidone, 1 - phenyl - 4 : 4- dimethyl - 3 - pyrazolidone, and 1 - (4<SP>1</SP> - # - hydroxyethylphenyl) - 3 - pyrazolidone respectively. Specifications 542,502, 581,772, 581,773, 702,162, 702,163, 712,355, 712,356, 757,271 and 767,705 [Group IV(b)] also are referred to.