Patent GB-544702-A (GB)
Title: Manufacture of positive photographic prints
IPC: G03C1/56
Filed: 1939-04-28
Abstract: 544,702. Photographic diazotype processes. KALLE & CO., AKT.-GES., and SUS, O. April 28, 1939, No. 12810. [Class 98 (ii)] Positive diazotype prints are obtained by exposing to light under a pattern material containing a non-coupling light-sensitized aryldiazo-N-sulphonate, which may be derived from a diazo compound of small coupling energy, and an azo component, which may have great coupling energy, the material not forming a dye on exposure to light but being developed by heat, for example by heating to above 100‹ C, preferably to 130 to 180‹ C. The diazo-sulphonate may have the general formula Z-R-NXY, where R represents a benzene nucleus which may be substituted by methyl, methoxy, ethoxy, propoxy, or butoxy groups, Z represents the diazo-sulphonate group, X represents alkyl, for example methyl, ethyl, propyl, isopropyl, butyl, or isobutyl, and Y represents hydrogen, alkyl, for example methyl, ethyl, propyl, isopropyl, butyl, or isobutyl, or aralkyl of the benzene series, for example, benzyl, Z being placed in p-position to the group -NXY. R may have an alkoxy group in the o-position to the diazo-sulphonate group, and a methyl group in the p-position to this alkoxy group. The light-sensitive layer may be made very weakly acid. The azo component may be phloroglucinol, resorcinol, compounds of the general formula R-CO-CH 2 -CO-NXY, where R represents alkyl or aryl and X and Y represent hydrogen, alkyl, aryl for example acetoacetic acid anilide, and naphthols substituted in the phenolic ring by an alkyl group containing a basic substituent, for example 1-dimethylaminomethyl-2-naphthol. The following substances may be added to the layers: polyhydric alcohols such as glycerol or glycol, urea, thiourea, thiosinamine, boric acid, primary sodium phosphate, zinc formate, zinc acetate, and sodium bisulphate. The heating may be effected by heated gases or vapours such as air or steam or heated rollers or plates. In examples, the sensitive material comprises (1) the sodium diazo-sulphonate from 1-diethylamino-4-amino-3-ethoxybenzene, phloroglucinol, thiourea, thiosinamine, and boric acid ; the diazo-sulphonate from other 1-dialkylamino- 3-alkoxy-4-aminobenzenes, such as 1-dimethylamino-3-methoxy-4-aminobenzene, 1-(N-ethyl:- N propyl-amino)-3-ethoxy-4-aminobenzene, 1-(N- ethyl : N-butyl-amino-3-ethoxy-4-aminobenzene, 1-(N-ethyl: N-hydroxyethyl-3-ethoxy-4-aminobenzene, may also be used; (2) the sodium diazosulphonate from 1 - diethylamino- 4-amino-3-methoxybenzene, 3-methyl-5-pyrazolone, thiourea, thiosinamine, and boric acid; acetoacetic acid anilide may be used instead of 3- methyl-5-pyrazolone; (3) the sodium diazo sulphonate from 1-diethylamino-3-ethoxy-4-aminobenzene, phloroglucinol, thiourea, and boric acid, paper previously coated on one side with a 10 per cent zinc acetate solution being sensitized with this solution; the corresponding propoxy or butoxy diazo-sulphonate, or the diazo-sulphonate derived from 1-monoethylamino-2-methyl-4- aminobenzene may also be used; (4) the sodium diazo-sulphonate from 1-diethylamino-4-aminobenzene, phloroglucinol, thiourea, and acetic acid, the paper being pre-treated with zinc acetate; the corresponding potassium, ammonium, or zinc diazo-sulphonate may also be used; (5) the sodium diazo-sulphonate from 1-(N-ethyl: N-benzylamino)-4-aminobenzene, phloroglucinol, thiourea, and boric acid, the paper being pre-treated with zinc formate and copper nitrate ; the diazo-sulphonate from 1-(N-ethyl:N-(2:6-dichlorbenzyl)- amino)-4-amino-benzene may also be used. Specification 491,095 is referred to. The Provisional Specification also refers to the addition of lead acetate to the light-sensitive layer.