Patent GB-678595-A (GB)
Title: Improvements in or relating to photographic light-sensitive materials
IPC: G03C1/835
Filed: 1950-07-06
Abstract: 678,595. Photographic material. DU PONT DE NEMOURS & CO., E. I. July 6, 1950 [July 19, 1949], No. 16933/50. Class 98 (ii). Photographic material comprises a support at least one light-sensitive silver halide emulsion layer, and a light-filtering layer comprising an acid addition salt with an acid dye of a vinylpyridine polymer which is insoluble in water but soluble in 1 per cent aqueous acetic acid, the dye being absorbent of light rays to which the emulsion layer is sensitive. The dye-salt layer may be coated on one side of a transparent support (e.g. film or transparentized paper) to form an antihalation layer, and one or more silver halide layers coated on the other side. Multilayer colour photographic material may have a yellow dye-salt filter layer between the outer blue-sensitive emulsion layer and a greeninsensitive red-sensitive silver halide emulsion layer, and a red dye-salt filter layer between the latter emulsion layer and a green-sensitive emulsion layer. Layers containing a mixture of dye-salts may be used. Suitable dyes are specified. The polymer may be one prepared by polymerizing an α-, #- or γ-vinyl pyridine or a homologue thereof containing an alkyl radicle of 1 to 4 carbon atoms in the pyridine ring. A mixture of two or more vinyl pyridines, or a mixture of a vinyl pyridine with up to 20 per cent by weight of another polymerizable vinyl or vinylidene compound or two or more of such compounds (e.g. styrene ; acrylic and alphaalkyl substituted acrylic esters and amides such as methyl and ethyl acrylates, methacrylamide, and N-methylacrylamide; acrylonitrile; and methacrylonitrile) may be used. The support may be first coated with a colloid layer (e.g. of polyvinyl alcohol, hydrolysed ethylene/vinyl acetate copolymer, gelatin, cellulose ether, cellulose acetate phthalate alkali metal salt, polyvinyl pyridine, or deacetylated chitin) before applying the dye-salt layer. In example 1, one side of a cellulose acetate film is coated with a poly-2-vinylpyridine salt of Pontacyl Fast Black BBO in methanol solution, and, after drying, the other side is successively coated with a gelatin substratum layer and a gelatino silver chlorobromide emulsion layer. After development of the exposed film, the dye-salt layer is removed in an aqueous acetic acid bath. In examples 2 and 3, the procedure is similar, using Pontamine Green BX and Pontamine Green S respectively. In example 4, a cellulose nitrate support is coated on the rear surface with an antihalation layer of polyvinyl alcohol containing Ink Blue, and on the other side successively with layers of a green-sensitive silver halide emulsion .containing m-(3-methylsalicylamido)-benzaldehyde polyvinyl acetal, a polyvinyl alcohol yellow filter layer containing n-cetyl betaine and poly-2-vinylpyridine-Tartrazine salt, and a blue-sensitive silver halide emulsion containing m-[p-5-(ethylcarbonato-3- methyl-1-pyrazolyl) -benzamido]-benzaldehyde polyvinyl acetal. After exposure and colour development, the material is washed, fixed in a bath containing hypo, sodium sulphite, borax, acetic acid, and potassium alum, washed, bleached in a potassium ferricyanide-boric acidborax bath, washed, fixed in a hypo bath, washed and dried. The support may be first coated with layers of a yellow colour-forming polyvinyl acetal and of polyvinyl alcohol before applying the other layers. In example 5, the procedure is similar, using another dye. Specifications 626,427 and 654,266 are referred to.