Patent GB-651690-A (GB)
Title: Improvements in diazotype photoprinting
IPC: G03C1/58
Filed: 1948-11-30
Abstract: 651,690. Photographic diazotype process. GENERAL ANILINE & FILM CORPORATION. Nov. 30, 1948, No. 31058. Convention date, Dec. 20, 1947. [Class 98 (ii)] Diazotype prints are prepared by exposing photographic diazotype material under the design to be copied, and coupling the residual diazo compound with an aliphatic nitro compound, wherein the carbon atom to which the nitro group is attached carries at least one reactive hydrogen atom. Coupling may be effected in an alkaline reacting medium, e.g. by exposing the exposed layer to the joint action of vapours of the nitro compound and of a volatile non-coupling nitrogen base, e.g. ammonia, or a volatile aliphatic amine, e.g. butylamine, or to the joint action of the vapours of the nitro compound and of an aqueous solution of methylamine, dimethylamine, ethylene diamine, or morpholine, or by treating the exposed material with a developing solution containing an aliphatic nitro compound and an alkaline reacting material. The nitro compound may be incorporated in the sensitive material. A mixture of the vapours of a nitro compound and ammonia may be used to develop two-colour effects on material having portions sensitized with a two-component diazotype composition and other portions sensitized with a onecomponent diazotype composition. Nitro compounds specified are nitromethane, nitroethane, 1-nitropropane, 2-nitropropane, nitroparaffins substituted, for example, by one or more OH, SO3H, or COOH groups or by carboxylic ester or amide groups, e.g. 1-nitrobutanol-2, 2-nitrobutanol-1, methyl nitroacetate and nitroacetamide. Development may be effected with an aqueous solution of methylamine, dimethylamine, ethylene diamine, or morpholine. In example (1), paper is coated with an aqueous solution of the zinc chloride double salt of N-#-hydroxyethyl: N-methylaminobenzene - p - diazonium chloride, ethylene glycol, citric acid, zinc chloride, and thiourea, and the exposed material is developed by exposure to the vapour produced by heating a mixture of (a) aqueous ammonia and nitromethane; (b) aqueous ammonia and nitroethane; (c) butylamine and 1-nitropropane; (d) aqueous ammonia, butylamine, and nitromethane; and (e) butylamine, nitromethane, and nitroethane. In example (2), the exposed material of example (1) is developed by moistening it with an aqueous solution of nitromethane and ethylene diamine, methylamine, dimethylamine, or morpholine. In example (3), the sensitizing solution is similar to that of example (1), except that the zinc chloride double salt of p - diethylaminobenzenediazonium chloride is used. The exposed material is developed with the vapour obtained by heating a mixture of aqueous ammonia and nitromethane. In example (4) translucent paper is sensitized with the composition of example (1), and after exposure is developed with the vapour obtained by heating a mixture of butylamine and nitroethane. In example (5), cellulose acetate foil is sensitized with an aqueous solution of the zinc chloride double salt of p-N-ethyl: N-#-hydroxyethylamino - o - methylbenzenediazonium chloride, isopropanol, citric acid, phosphoric acid, zinc chloride, thiourea, and acetone. The exposed material is developed with the vapour obtained by heating a mixture of aqueous ammonia and nitromethane. In example (6), gelatine-coated paper is coated with a composition similar to that of example (1) except that it contains the zinc chloride double salt of p-ethylamino-mmethylbenzenediazonium chloride. The exposed material is developed with the vapour obtained by heating a mixture of nitromethane, butylamine, and water. In example (7), paper is coated with an aqueous solution of citric acid, thiourea, zinc chloride, 2-nitrobutanol-1, and the zinc chloride double salt of p-diazo-N : N- dimethylaniline. The exposed material is developed with ammonia vapour. The diazo compound may also be the zinc chloride double salt of p-N-methyl: N-#-hydroxyethylaminobenzenediazonium chloride, p-diethylamino-oethoxybenzenediazonium chloride, p - ethylamino - m - methylbenzenediazonium chloride, or 4 - benzoylamino - 2 : 5 - diethoxybenzenediazonium chloride.