GB722397A - Improvements in or relating to photographic colloid-silver halide emulsions - Google Patents

Abstract

722,397. Photographic colloid-silver halide emulsions. DU PONT DE NEMOURS & CO., E. I. Dec. 16, 1952 [Jan. 11, 1952], No. 31889/52. Class 98 (2). An emulsion containing an anti-plumming or anti-bronzing compound has dispersed therethrough a polymeric amino-nitrogen-containing material which is insoluble in water and dilute alkalis but soluble in 1 per cent acetic acid. Preferably the anti-plumming or anti-bronzing compound is in finely-divided form, and it is still more preferred to have this compound dispersed in particles of the polymeric aminonitrogen-containing material, in which case the latter prevents washing out of the former during development but permits release thereof in acid-stop or acid-fixing treatment, and so allows for use of less than a third of the usual amount of the compound to produce anti-plumming or anti-bronzing effects. In the preferred aspect of the invention the emulsion is used for printing papers, but use in portrait and lithographic film and for seismographic and spectrographic line recording is referred to. The emulsion colloid may be gelatine, or numerous other materials as described with reference to Specifications 598,477 and 600,023. 1-phenyl- 5-mercaptotetrazole is specified as anti-plumming compound in five examples, and in five comparison tables which indicate contrast and presence or absence of plumming under various conditions; other 5-mercaptotetrazoles as of Specification 561,875, and thiouronium salts as of Specification 613,400 may be used. The polymeric amino-nitrogen-containing materials are such as are capable of forming hard resin-like films, although they are not so used in the invention, and they are of three classes: (1) cellulose derivatives; (2) synthetic resins; (3) protein derivatives, all of which are provided with sufficient amino-nitrogen groups to give the required solubility characteristics and all of which are described in Specification 537,232. In the five examples the l-phenyl-5-mercaptotetrazole anti-plumming compound and polymerized diethylaminoethyl methacrylate, the preferred amino-nitrogen-containing material, in solvents including ethyl and methyl alcohol and toluene, together with a dispersing agent as of Specification 592,676, are blended into a chloro-bromide emulsion to produce the desired dispersed particles, contact type procedure is followed for further preparation and coating, and after exposure processing is effected in a specified metol-quinol developer and acid fixer; and drying is effected on hot and on cold ferrotype plates for evaluation of plumming. The anti-fogging property of the l-phenyl-5-mercaptotetrazole anti-plumming compound is referred to.