Patent GB-732424-A (GB)
Title: Improvements in or relating to photographic diazotype processes and materials
IPC: G03C1/60
Filed: 1953-07-30
Abstract: 732,424. Photographic diazotype layers. CHEMISCHE FABRIEK L. VAN DER GRINTEN N.V. July 30, 1953 [April 28, 1953], No. 21184/53. Class 98 (2). The light-sensitive surface of a one or two component diazo material is characterized by the presence of a polymer of an ester of methacrylic acid of softening point at least 70- 80‹ C., applied as an aqueous dispersion. The polymer may be incorporated in the lightsensitive coating mixture, but better results are given when the polymer dispersions are first spread on a surface and, when no longer appearing wet, or when dried, are followed by an aqueous solution containing the diazo compound. The diazotype layers may contain stabilizers such as acid substances and thiourea; coating assistants such as gelatin, gum arabic and isopropyl alcohol; anti-curling substances such as glycerin and polyethylene glycol; metal salts such as aluminium, nickel or zinc sulphate, and substances to counteract the feathering of inks when used to write or draw on prints made with the materials, such as symmetrical diphenylguanidine or di-o-tolylguanidine. The polymethacrylate dispersions may contain polyvinyl acetate dispersion or cellulose ether to facilitate spreading thereof. Fifteen examples specify proprietary products as the methacrylic ester polymer dispersions but with quantitative details of the dispersion and diazo coating liquids and coupling solutions ; examples I and VIII quoting two component mixtures including p-diazo-diethyl or ethylhydroxyethyl-aniline zinc chloride and 2- diazo - naphthol - 1 - 5 sulphonic acid respectively for ammonia development ; in examples II and VIII the polymer dispersions are contained in the sensitizing liquid; in other examples the polymer dispersions are applied as precoat, followed by one component diazo sensitizing coatings for thin layer type development with fast coupling diazo compounds, including p - diazo - 2 - 5 - diethoxy - (4<SP>1</SP>- ethoxyphenyl) - 4 - benzene chloride, p - diazo- 2-5-diethoxydiphenyl-sulphide zinc chloride double salt and the corresponding beta-naphthyl derivative, p-diazo-di-n-butylaniline zinc chloride double salt, p-diazo-2.5-diethoxy-benzanilide zinc chloride double salt, p-diazoethyl-benzyl-aniline zinc chloride double salt, p - diazo - o - chloro - diethyl - aniline zinc chloride double salt, p-diazo-diphenylamine chloride, p - diazo - 2,5 - diethoxy - (4<SP>1</SP> - methoxyphenyl benzene chloride, p-diazo-2,5-dimethoxy - 4<SP>1</SP> - methyl - diphenyl - sulphide, pdiazo - ethyl - benzyl - aniline chlorostannate and p-diazo-ethyl-benzyl aniline nitrate. Paper of various specified varieties is used as support except for example VI, opaque cloth. Examples III and IX describe good results with use of copolymer dispersions of methacrylic acid methyl ester and acrylonitrile. Inferior results are mentioned using dispersions in example V of acrylic ester, example VIII of polyvinyl acetate, examples VIII and XII of silica, examples X and XIV of methacrylic ester of softening point 40‹ C. and example XV of polystyrene. Specifications 625,999, 640,491 and 647,197 are referred to.