Patent GB-1495464-A (GB)
Title: Photographic material having polymeric neutralizing layer
IPC: G03C8/52
Filed: 1975-09-11
Abstract: 1495464 Photographic material having polymeric acid neutralizing layer FUJI PHOTO FILM CO Ltd 11 Sept 1975 [11 Sept 1974] 37499/75 Heading G2C [Also in Division B2] A sheet material capable of neutralizing an alkaline photographic processing solution comprises a support having thereon, a layer comprising an acidic polymer containing before cross-linking at least three millimoles of carboxyl groups per gram of polymer, 1% to 40% of the carboxyl groups having been neutralized into the salt form and having been cross-linked with a compound containing in its molecule at least two aziridyl and/or glycidyl groups and/or groups which can be converted into aziridyl or glycidyl groups during the reduction with the polymer. Preferably the carboxyl group-containing polymer contains 5 to 17 millimoles per gram of carboxyl groups. Homopolymers or copolymers of vinyl monomers containing carboxyl groups are particularly useful such as polymers of acrylic acid, methacrylic acid, maleic anhydride, the half-esters and half-amides of maleic acid, cinnamic acid, crotonic acid, citraconic acid, p-carboxystyrene and a vinyl-carboxymethyl ether. Suitable comonomers are ethylene, vinyl acetate, styrene, alkyl vinyl ethers, acrylic esters, methacrylic esters, acrylamide and methacrylamide Preferably the polymer has a molecular weight of 5,000 to 500,000. The acid may be neutralized with alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal salts of weak acids, ammonium hydroxide and organic amines and precursors of these. Numerous suitable specific examples are given. Numerous suitable crosslinking agents of the types specified are listed. The material is useful in diffusion-transfer photographic systems (see Ex 6 and 7). The polymeric acid layer may be incorporated into these systems in various arrangements: (1) the polymeric acid layer and an image-receiving layer are successively coated on a first support, silver halide emulsion is coated on a second support and the processing solution is sprayed in a layer between the imagereceiving layer and the silver halide emulsion layer. Alternatively, (2) the polymeric acid layer and the silver halide emulsion layer are successively coated on a first support, an image-receiving layer on a second support and processing solution is fed in the layer formed between the two. In another arrangement (3) the polymeric acid layer, an image-receiving layer and (if desired) a stripping layer or a light reflecting layer, and a silver halide emulsion layer are successively coated on a support and a processing is supplied on the surface of the silver halide emulsion layer. In a further arrangement (4) the polymeric acid layer is coated on a first support, an image-receiving layer (and if desired) a stripping layer or a light-reflecting layer,  and a silver halide emulsion layer are coated on a  second support, and a processing solution is fed in the layer formed between the polymeric layer and the emulsion layer. In the above embodiments the polymeric acid layer is desirably isolated from the processing solution layer by a neutralization ratecontrolling layer or timing layer, which is capable of preventing an undersirable reduction in photographic density which results from a premature decrease in pH of the system. The timing layer may be of gelatine, polyvinyl alcohol, polyvinyl propyl ether, polyacrylamide, hydroxypropyl methyl cellulose, isopropyl cellulose, partially butylated polyvinyl alcohol, partially hydrolysed polyvinyl acetate and copolymers of #-hydroxyethyl methoxylate with ethyl acrylate.