GB443611A - Method of obtaining photographic contrasts and sensitive layers therefor - Google Patents

Abstract

443,611. Photographic diazotype processes. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, Emmasingel, Eindhoven, Holland. Nov. 9, 1934, No. 32298. Convention date, Jan. 19. [Class 98 (ii)] In a layer developable by water or water vapour only, the diazonium compound and the azo coupling component or a compound capable of oxidation by the diazo body to form a coloured substance are applied to a carrier and the prepared layer is maintained at a degree of dryness sufficient to prevent the formation of dye, up to the moment of exposure. One or both of the dyestuff components may be applied in the form of powder. The coupling component may also be furnished by partial decomposition of the diazo compound by a preliminary exposure to light. If necessary, alkali, in solution or as a powder, may be applied to the layer. The degree of dryness varies with the nature of the compounds used. In examples : (1) paper is coated with a solution of the zinc chloride double salt of p-diphenylaminodiazonium chloride, dried and rubbed with a powder consisting of R-salt and anhydrous soda or phloroglucin and sodium bicarbonate; (2) paper bearing the diazo compound under (1) above is rubbed with a powder of phloroglucion or Schõffer's acid, or the latter may be applied in alcoholic solution; (3) paper treated with 1-diazonium-2-hydroxynaphthalene-4-sulphonic acid and a powder of resorcin and anhydrous soda is applied ; (4) paper with a diazonium compound as under (1) above is rubbed with a powder of alpha naphthol ; (5) paper is coated with alpha-naphthol, dried, and a powder of the diazo compound under (1) above applied; (6) paper is rubbed with a powder of the zinc chloride double salt of p-diphenylamine diazonium chloride and phloroglucinol ; (7) paper is treated with 2-diazonium- 1-hydroxybenzene-4-sulphonic acid and copper nitrate, dried and exposed to uniform light. It is then exposed under a tracing ; (8) paper is coated with 2-diazonium-1-hydroxy-5-methylbenzene-4-sulphonic acid and copper nitrate and treated as under (7) above ; (9) paper is prepared with the composition under (7) above, exposed to uniform light, rubbed with a powder of 2-diazonium-1-hydroxy-5-methylbenzene-4-sulphonic acid and exposed behind a tracing ; (10) paper is soaked in a solution of alpha-naphthalene diazonium chloride, exposed to uniform light, covered with a powder of p - diphenylaminodiazonium chloride and exposed under a tracing. The development is in all cases by the use of water vapour. Specification 391,052 is referred to.