GB979577A - Photo-lithographic printing - Google Patents

Abstract

979, 577. Photolithographic printing. KODAK Ltd. Dec. 21, 1960 [Dec. 21, 1959], No. 30229/64. Divided out of 978,744. Headings G2C and G2M. A method of photolithographic printing comprises the steps of exposing a silver halide emulsion layer to a subject; developing the exposed layer, while in contact with a reception layer of a tannable hydrophilic organic colloid containing a silver-precipitating agent, with a solution containing a developing agent capable of oxidation in the presence of a tannable hydrophilic organic colloid to form an oleophilic image together with a silver halide solvent, whereby the undeveloped silver halide of the exposed layer is transferred to the reception layer and an oleophilic image is formed thereon; inking the image so formed while it is still moist with greasy printing ink, and printing therefrom. The reception layer may be coated on a separate support or coated on the surface of the silver halide emulsion layer. As described a film support was coated with a gelatino-silver chlorobromide emulsion containing mucochloric acid, and this layer was overcoated with a dispersion of zinc sulphide in gelatin containing mucochloric acid. After exposure development was effected with a solution containing 4-phenyl catechol, sodium thiosulphate, sodium carbonate and sodium hydroxide. Thereafter the film was rinsed in dilute acetic acid, inked, treated with dilute phosphoric acid fountain solution and ink printer made. Other developing agents referred to as suitable are chloro- or bromo-hydroquinone, pyrogallol or its formic or acetic acid esters, 4-n-butylpyrogallol, 4-tert-butylcatechol, 4:5-dibromocatechol, 3:5:6-tribromo-4-phenylcatechol, nordihydroguaiaretic acid, 1-phenyl-3-(N-n-hexylcarboxamide)-4-[(#-hydroquinoylethyl)-phenylazo]- 5- pyrazolone, and pyrogallol together with a non- tanning developer such as metol or a 3-pyrazolidone. In place of gelatin the hydrophilic organic colloid may be soy bean protein, casein, polyvinyl alcohol, or hydrolysed cellulose esters, and instead of zinc sulphide other silver-precipitating agents or development nucleii as in Specification 868,241 may be used.