Improvements in or relating to the production of direct positives by the silver saltdiffusion process

摘要

962,976. Photographic processes and materials. AGFA A. G. Sept. 7, 1961 [Sept. 8, 1960], No. 32216/61. Heading G2C. The silver halide diffusion-transfer process is carried out in the presence of a thioether containing several hydroxyl groups or a polyether thioether containing at least 2 ether and 2 thioether groupings. An image-receiving layer with nuclei, a silver halide layer and a developer solution (not containing hypo), including the above thioether materials are comprised within the invention. Instances of transfer without nuclei and without hypo are described. In Example 1 baryta paper is provided with a coating of a polyethylene oxide-thiodiglycol condensate with silver sulphide and an overcoating of carboxymethyl cellulose to form the receiving layer and seven transfers thereto are made using a developer containing only sodium sulphite, caustic soda, hydroquinone, 1-phenyl-3-pyrazolidone and potassium bromide. Example 2 describes a receiving layer prepared from gelatin, carboxymethyl cellulose and an oxethylated resorcinol thiodiglycol condensate only, for copy production using a hypocontaining developer. Further examples use (3) an oxethylated-1, 4-hexanediol thiodiglycol, (4) an ethylene oxide, propylene oxide, butane-1,4-diol copolymer thiodiglycol and (5) a polyethylene oxide 3, 8-dithiadecane-1, 10-diol condensates for the transfer; examples 1-4, however, are each continued with quotations of other condensates to replace those stated. 29 examples of the thioethers, with dithiodiglycol HOCH 2 CH 2 . S. S. CH 2 CH 2 OH as the simplest quoted, are provided. Specifications 647,911, 895,674 and 896,999 are referred to.