Patent GB-439005-A (GB)
Title: Improved methods of obtaining photographic contrasts by means of diazonium compounds and sensitive layers for use therein
IPC: G03C1/62
Filed: 1935-01-31
Abstract: 439,005. Photographic diazotype processes. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, Emmasingel, Eindhoven, Holland. Jan. 31, 1935, No. 3180. Convention date, Feb. 3, 1934. [Class 98 (ii)] Photographic contrasts are produced by light action using a diazonium compound and a mercurous salt, the picture resulting from the reaction between the mercurous salt and the light decomposition product of the diazonium compound. The mercurous salt may be incorporated in the sensitive layer or the layer treated after exposure with a solution of the salt. The image may be rendered stable by the salt of a metal lying higher in the electrochemical series than mercury, for example, silver, gold, or platinum. This salt may be included in the layer before exposure or the layer after-treated with the salt, e.g. silver nitrate. In this case the picture may be fixed with sodium sulphite or developed with a metol citric acid or metol tartaric acid solution. The carrier for the layer may be paper, linen, regenerated cellulose, or acetyl cellulose superficially saponified. The process may be used for reflex copying. In examples: (1) paper is soaked in mercurous nitrate solution, then in a solution of benzene diazo boron fluoride, exposed and washed. Other diazo compounds which may be used are given in the Specification ; (2) paper is soaked in a solution of 1- hydroxybenzene - 4 - potassium-diazosulphonate and mercurous nitrate, exposed and washed. Other diazo compounds are referred to ; (3) paper is sensitized with a solution of mercurous carbonate and 1-hydroxy-2-diazo-benzene-4-sulphonic acid in hydrofluoboric acid, exposed and washed; (4) paper coated with gelatin is soaked in 1-hydroxy-2-diazo-benzene- 4-sulphonic acid and mercurous .nitrate, exposed, developed with silver nitrate solution and washed ; (5) paper or linen is sensitized with 2-diazo-1-hydroxy-6-methyl-benzene-4-sulphonic acid and mercurous nitrate exposed, washed, and fixed by a solution of decinormal nitric or acetic acid; (6) paper is soaked in a solution of 1-hydroxy-2-diazo-6-methyl-benzene-4-sulphonic acid and mercurous nitrate and dried over phosphorus pentoxide, after exposure it is washed and developed with silver nitrate ; (7) regenerated cellulose is sensitized with 1-hydroxy-2-diazo-6-methylbenzene-4-sulphonic acid and mercurous nitrate; (8) acetyl cellulose is superficially regenerated and sensitized as under (7) with the addition of silver nitrate, exposed, washed and treated with sodium sulphite. Alternatively it may be developed with metol and citric acid. Other diazo compounds suitable for the above are given in the Specification ; (9) paper soaked in p-diphenylamino-diazo-boronfluoride and mercurous nitrate is treated as in example 3 ; (10) paper is bathed in mercurous nitrate, then in sodium sulphate, dried, and soaked in 1-diazo-2-hydroxynaphthalene-4-sulphonic acid and treated as in example 3 ; (11) paper is soaked in a solution of mercurous nitrate, dried, and soaked in a solution of 2-hydroxy-1- diazo-naphthalene-4-sulphonic acid and silver nitrate, exposed and developed by keeping in a moist atmosphere; (12) acetyl cellulose is sensitized as in example (11) and treated as in example (8) ; (13) paper is treated with mercurous nitrate and 1-diazo-2-hydroxy-naphthalene-4-sulphonic acid, exposed and developed with auric chloride; (14) paper is sensitized with 1-diazo-2-hydroxy-naphthalene-4-sulphonic acid, dried, exposed and treated with mercurous nitrate. It is then washed and treated with silver nitrate. Alternatively, the paper may be rubbed with a powder of mercurous nitrate and exposed to a moist atmosphere.