Patent GB-1442912-A (GB)
Title: Photographic dye diffusion transfer process
IPC: G03C8/00
Filed: 1974-05-31
Abstract: 1442912 Photographic dye diffusion transfer process AGFA - GEVAERT AG 31 May 1974 [1 June 1973] 24262/74 Heading G2C A photographic dye diffusion transfer process for the production of a positive coloured transfer image comprises (A) producing a negative silver image by development in a light-sensitive silver halide emulsion layer which has been imagewise exposed which layer contains a non-diffusible silver halide developer compound which is incapable of an oxidative condensation reaction with a non- diffusible dye-giving compound, the development being effected in the presence of catalytic quantities of a diffusible auxiliary developer, (B) transferring by means of a silver halide solvent the undeveloped silver halide into an associated layer of binder which contains development nuclei, a non- diffusible dye - giving compound and a non- diffusible developer compound which in its oxidized form is capable of undergoing a condensation reaction with the dye - giving compound to release a diffusible preformed dye therefrom, (C) developing the transferred silver halide at the development nuclei to form a positive silver image and simultaneously an image distribution of developer oxidation products, the development being effected in the presence of catalytic quantities of a diffusible auxiliary developer, (D) causing a condensation reaction between the developer oxidation products produced in this associated layer and the non- diffusible dye - giving compound to release a diffusible dye therefrom, and (E) transferring the diffusible dye to an image-receiving layer to form a dye image therein. The light-sensitive silver halide emulsion layer, the associated binder layer and the image-receiving layer may be in a photographic  monosheet. An opaque layer maybe present between the image-receiving and associated binder layers. The silver halide emulsion layer may contain a non-diffusible hydroquinone compound e.g. of the Formula:- where R 1  is a straight or branched chain alkyl, and R 2  is H, SO 3 H or a straight or branched chain alkyl and R 1  and R 2  together contain at least 12C. The non-diffusible developer compound in the associated binder layer may be a p-phenylendiamine containing a primary animo group or a 1,2-dihydroxybenzene derivative which is free of substituents in at least one para-position to an OH group. The auxiliary developer may be used at 0À02-0À2 mole per mole silver halide and may be p-methylanimophenol, 2,4-diaminophenol, reductone or 1-phenyl- 3-pyrazolidone. The non-diffusible, dye - giving compound in the associated binder layer may have the Formula where R 1  is H, alkyl containing up to 20C, aralkyl, aryl, or amino substituted by alkyl or aryl, and two alkyl groups attached to the N atom may be joined together to from a ring; R 2  is alkyl containing up to 20C, aralkyl aryl, acyl derived from aliphatic carboxylic acid containing up to 20C or an aromatic carboxylic acid or an amino group substituted by alkyl or aryl, and two alkyl groups attached to the N atom may be joined together to form a ring, or R 1  and R 2  together supply the ring members required for completing a carboxyclic or heterocylic group; at least one of R 1  and R 2  carrying the group A; X is sulphonyl, carbonyl or single chemical bond; A is a photographically inert group which confers diffusion resistance; and B is a dye group. The silver halide solvent may be in a transparent cover sheet (see Examples). Coloured transimages having improved image whites are obtained and separating layers in a given colour unit of the material and between the light-sensitive element and the image-receiving layer may be dispensed with in view of the use of non-diffusible developer in the layers of the light-sensitive element.