Patent GB-1351972-A (GB)
Title: Dye diffusion transfer process for the production of positive colour photographic images
IPC: G03C8/10
Filed: 1971-07-02
Abstract: 1351972 Photographic diffusible dye diffusion transfer material AGFAGEVAERT AG 2 July 1971 [2 July 1970] 31151/71 Heading G2C A photographic material comprises a lightsensitive dye-releasing element on a support, which light-sensitive element comprises at least one combination of a first light-sensitive silver halide emulsion layer having associated therewith a diffusion-fast DIR (development inhibitor releasing) compound which reacts with oxidation products of the colour developer to split off a diffusible development inhibiting substance which inhibits development in the second layer and a second developable emulsion layer containing reducible metal salt which contains a non- diffusing dye-releasing compound of the formula:- wherein R 1  is H, 1-20C alkyl, aralkyl, aryl or an amino group which is substituted with alkyl or aryl, and when two alkyl groups are attached to the N they may be joined to form a ring; R 2  is 1-20C alkyl, aralkyl, aryl, acyl derived from an aliphatic carboxylic acid containing up to 20C or from an aromatic carboxylic acid, or an  amino group which is substituted with alkyl or aryl, in which case when two alkyl groups are attached to the N they may be joined to form a ring; or R 1  and R 2  taken together complete a carbocyclic or heterocyclic group; at least one of R 1  and R 2  carrying the group A: X is sulphonyl, carbonyl or a single chemical bond; and either A is a photographically inert group which renders the compound resistant to diffusion; and B is a dye radical; or A, either alone or together with R 2 , is a dye radical; and B is a photographically inert group which renders the compound resistant to diffusion. The DIR compound may have the formula:- C p -S-R wherein C p  is a colour coupler radical; and R is an organic radical which is split off together with the sulphur atom of the thioether bridge in the reaction with the oxidation products of the colour developer to form a diffusible mercapto compound which has a development inhibiting action, or the formula:- wherein E has the same meaning as R above, R in this general formula is H, alkyl, aralkyl, cycloalky. aryl, a heterocyclic group having 5 or 6 ring members which may contain one or more hetero atoms and condensed benzene or naphthalene rings or -S-E and X activates the C atom shown and is -COR 1 , -CONH 2 , -CONHR 1 , -CON(R 1 ) 2 , -SOR 2 R 1 , -SO 3 H, -SO 2 OR 1 , -SO 2 N(R 1 ) 2 , -CN, [-N(R 1 ) 3 ]<SP>+</SP> or -S-E wherein R 1  is a saturated or olefinically unsaturated aliphatic group containing up to 18C which may be substituted, aryl or a 5- or 6- membered heterocylic group which may contain one or more hetero atoms and condensed benzene or naphthalene rings; two of the substituents R 1  taken together may complete a saturated 5- or 6-membered ring which contains nitrogen. The dye radicals A, B or Fb may be  derived from azo, anthraquinone, phthalocyanine, indigoid or triphenylmethane dyes. The released dye may be transferred to an imagereceiving layer containing a mordant for the dye. The image-receiving layer may be on the same support as the dye-releasing element. The image-receiving layer may or may not be separated from the light-sensitive material after dye transfer. The aqueous alkaline processing composition may contain a white pigment and be spread between the dye-releasing element and the image-receiving element. An opaque layer may be present between these elements before exposure, which layer is permeable to alkali and to diffusing dyes. The material may comprise a transparent support bearing an imagereceiving layer, the light-sensitive element and a covering layer which is impermeable to light. A diffusion fast colour developer may be present in the first light-sensitive silver halide emulsion layer which contains the DIR compound. No dye is actually created or destroyed in this invention and therefore the emulsion layer and the image-receiving layer after transfer of the dye have the same colour but the opposite gradation. Reference has been directed by the Comptroller to Specification 932272.