US3702248A

US3702248A - Bleach-fix additives

Info

Publication number: US3702248A
Application number: US100839A
Authority: US
Inventors: David Gerald Alcock; John Colin Brown; Enzo Piccotti; Norman John Iungius
Original assignee: Ilford Ltd
Current assignee: Ilford Imaging UK Ltd
Priority date: 1969-12-23
Filing date: 1970-12-22
Publication date: 1972-11-07
Anticipated expiration: 1989-11-07
Also published as: SU383337A3; DE2063576C3; NL166554C; NL166554B; JPS4834767B1; ZA708653B; FR2074216A5; GB1297653A; CH557045A; DE2063576B2; DE2063576A1; CA968611A; NL7018729A

Abstract

THIS APPLICATION DESCRIBES A BLEACH-FIX BATH FOR USE IN PROCESSING COLOUR PHOTOGRAPHIC MATERIAL COMPRISING A MILD OXIDISING AGENT, A SILVER-HALIDE SOLVENT AND A BLEACHFIX ACCELERATOR WHICH IS A WATER SOLUBLE SELENIUM COMPOUND SELECTED FROM DEFINED CLASSES OF SELENOSEMI-CARBAZIDES AND ANALOGOUS BIS-COMPOUNDS, 1,2,4-TRIAZOLE-3SELENOLS AND 5,5-BIS, 1,2,4-TRIAZZOLE-3-SELENOLS, THE INVENTION INCLUDING THE BATHS PER SE AND THEIR USE IN COLOUR PROCESSING OF PHOTOGRAPHIC MATERIAL.

Description

United States Patent 01 fice 3,702,248 Patented Nov. 7, 1972 3,702,248 BLEACH-FIX ADDITlVES David Gerald Alcock, John Colin Brown, Enzo Piccotti, and Norman John Iungius, 'Ilford, England, assignors to Ilford Limited, Ilford, Essex, England No Drawing. Filed Dec. 22, 1970, Ser. No. 100,839 Claims priority, application Great Britain, Dec. 23, 1969, 62,680/ 69 Int. Cl. G030 7/16 US. CI. 9622 14 Claims ABSTRACT OF THE DISCLOSURE This application describes a bleach-fix bath for use in processing colour photographic material comprising a mild oxidising agent, a silver-halide solvent and a bleachfix accelerator which is a water soluble selenium compound selected from defined classes of selenosemi-carbazides and analogous bis-compounds, 1,2,4-triazole-3- selenols and 5,5-bis, 1,2,4-triazole-3-selen0ls, the invention including the baths per se and their use in colour processing of photographic material.

This invention relates to the processing of photographic material comprising silver halide emulsion layers to yield material having colour dye images therein.

In the processing of conventional colour photographic material a developable silver salt image is developed with an aromatic primary amino developing agent of the paraphenylene diamine type (a so-called colour developer) in the presence of a compound (a so-called colour coupler) which will combine with the oxidation products of the colour developer to form an azomethine or quinone-imine dye. The dye is thus formed in situ with the developed silver image. Subsequently the product must be treated with a bleach bath and a fixing bath or a combined bleach-fix bath thereby to remove silver and any residual silver halide or other silver salt, leaving in the product only the dye image.

In the silver-dye-bleach process of colour photography the photographic material comprises at least one silver halide emulsion layer which includes as a dispersion therein an organic dyestufi of the type which can be destroyed (or bleached) by finely divided silver in a suitable treatment bath. The organic dyestutt' is usually an azo dye. Most commonly three such silver halide emulsion layers are present each of which is sensitive to a different region of the visible spectrum and each of which contains a difierent azo dye. The usual processing sequence for the production of a dye image in the material is after an imagewise exposure to develop the material in a black and white developer. The development is then stopped and the unexposed silver halide is fixed out. Then after washing the material is treated in a dye-bleach bath which oxidises the silver image and simultaneously reduces (bleaches) the dye in the region of the silver image. The silver salts and any residual silver must then be removed. This is usually accomplished by washing the material after its treatment in the dye-bleach bath and then treating it in a bleach bath followed by a fixing bath or treating it in a combined bleach-fix bath. The photographic material then contains a dye image only; this dye image being usually a direct positive reproduction of the original.

In one commercially available silver-dye-bleach material the amount of residual silver left after the dye-bleach step is not negligible because this material requires to be processed so that the dye-bleach step is terminated before all the image silver has been used in reducing the dye. Thus in the processing of this silver-dye-bleach material in particular it is essential that an effective silver bleach step succeeds the dye-bleach step in order to ensure that the residual silver is removed as completely as possible from the material.

In both the processing of conventional colour photographic material and in the processing of silver-dye-bleach material the use of a combined bleach-fix bath is preferable because it results in a reduction of the processing time and of the cost of processing equipment required. Normally a bleach-fix bath comprises a mild oxidising agent for example a ferric chelate complex, a cupric complex, a salt or a cobalt (III) complex together with a silver halide solvent or fixing agent for example a watersoluble thiosulphate or a water-soluble thiocyanate. Strong oxidising agents cannot be used because they tend to oxidise the silver halide solvent.

Stable bleach-fix solutions comprising ferric chelate complexes and sodium thiosulphate may be obtained but because of the weak oxidising power of the ferric chelate complex such bleach-fix bath can only be used commercially for the processing of photographic materials with a fairly low silver content.

According to the present invention in the processing of photographic material comprising silver halide emulsion layers to yield material having colour dye images therein there is provided a bleach-fix step which comprises treating the photographic material with a stable bleach-fix bath which comprises an aqueous solution of a mild oxidising agent and a silver halide solvent which is either a water-soluble thiosulphate or a water-soluble thiocyanate in the presence of a bleach-fix accelerator which is selected from (a) a water-soluble selenosemicarbazide of the general Formula 1:

R1 R Se wherein one of R and R is a hydrogen atom or an alkyl, aralkyl or aryl group or a group R CO- where R is a hydrogen atom or an alkyl, alkoxy or heterocyclic group, or a group NR7R3--CSe where R and R are each hydrogen atoms or alkyl groups and the other of R and R is a hydrogen atom or an alkyl group, R is a hydrogen atom or an alkyl, aralkyl or aryl group, one of R and R is a hydrogen atom or an alkyl, aralkyl or aryl group and the other of R and R is a hydrogen atom or an alkyl group but at least one of R R or R being a hydrogen atom and there being not more than one group selected from aryl, aralkyl and heterocyclic present in the compound or (b) a water-soluble compound of the general Formula II:

wherein each of R R is a hydrogen atom or an alkyl group but there being not more than four alkyl substituent groups in the compound and at least one of R R R R14, R anl R being a hydrogen atom and X is a linkage group wherein m is 0 to 4, or (c) a water-soluble l,2,4-triazole-3-selenol wherein the S-carbon atom carries a substituent selected from a hydrogen atom or an alkyl, hydroxy, amino, alkylamino, arylamino ar aralkylamino group and one of the nitrogen atoms carries a substituent selected from a hydrogen atom or an alkyl, aralkyl or aryl group, or (d) a water-soluble 5,5-bis-1,2,4-triazole-3-sele- 1101 wherein the triazole rings are linked directly or via a link 2)n wherein n is l-4 and wherein one nitrogen atom in each of the triazole rings carries a substituent selected from a hydrogen atom and an alkyl, aryl and aralkyl group.

It is to be understood that the triazole-selenol compounds of (c) and (d) above have been defined with reference to their selenol form but these compounds may be present in their tautomeric selenone form in which case there is an additional substituent hydrogen atom in the ring or rings.

The preferred compounds for use in the present invention are those of Formula I wherein each of R R are hydrogen atoms or alkyl groups. Other preferred compounds are those of Formula II wherein each of *R R is a hydrogen atom. The preferred triazole-selenols of (c) are those wherein the S-carbon atom carries an alkyl or hydroxy group and one of the nitrogen atoms carries a substituent hydrogen atom. The preferred bis-triazole-selenols of (d) are those wherein one nitrogen atom in each of the triazole rings carries a substituent hydrogen atom.

By stable bleach-fix bath which comprises an aqueous solution of a mild oxidising agent and a silver halide solvent is meant a bleach-fix bath wherein the oxidising agent is strong enough to bleach the silver but is not strong enough to oxidise the silver halide solvent, i.e. the thiocyanate or the thiosulphate, to an appreciable degree.

The preferred mild oxidising agents for use in the present invention are ferric chelate complexes or diaquo-tetramminecobalt (III) complexes.

By ferric chelate complex is meant a co-ordination compound of the ferric ion and a compound which comprises nitrogen and/or oxygen-containing co-ordinating groups. The most important co-ordinating groups are amino, heterocyclic nitrogen, carboxyl and carbonyl groups.

The preferred ferric chelate complex for use in the bleach-fix step of the present invention is a ferric ethylenediamine-tetraacetic acid complex. It is to be understood that this compound may be used as such in the preparation of a. bleach-fix bath or it may be formed in situ in a bleachfix bath by ethylenediaminetetraacetic acid reacting with a ferric salt e.g. ferric chloride. In the examples which follow the ferric ethylenediaminetetraacetic acid complex has been formed in situ.

Other ferric chelate complexes which may be used in the present invention are for example pyridine-2:6-dicarboxylateferrate (III) complex, iminodiacetatoferrate (IH) complex and nitrilo-triacetate-ferrate (III) complex.

The selenosemicarbazides of the above Formula I are known compounds as shown by the references set forth below The following Formula III indicates the nitrogen atom referred to in the references.

ISc N Hr-N H--NH,

( (III) 4-phenylselenosemicarbazide-preparation described by Jensen and Frederiksen, Z. anorg. allgem. Chem. 230, 31-3 (1936) 2-phenylselenosemicarbazide-preparation described by Mautner and Kumler, J. Amer. Chem. Soc. 97-101 (1956) 4-ethylselenosemicarbazidepreparation described by Huls and Renson, Bull. soc. chim. Belges 65, 684-95 (1956) 4 propylselenosemicarbazide-preparation described by M. Colland-Charon, Huls and iRenson, Bull. soc. chim. Belges 71, 541-53 (1962) preparations described by Colland-Charon, Huls and Renson, Bull, soc. chim., Belges 71, 554-62 (1962):

1-phenylselenosemicarbazide, and l-(p-tolyl) selenosemicarbazide 4 preparations described by Jensen, Felbert, Pedersen and Svaholm, Acta chem. Scand, 20 (l) 278-81 (1966):

1-methylselenosemicarbazide 2-methylselenosemicarbazide 4-methylselenosemicarbazide l, l-dimethylselenosemicarbazide 1,2-dimethylselenosemicarbazide 1,4-dimethy1selenosemicarbazide, and 1,2,4-trimethylselenosemicarbazide preparations described by Bulka, Ahlens and Tucek,

Chem. Ber. 100 (4) 1373-8 (1967):

2-methyl-4-phenylselenosemicarbazide 4- (p-chlorophenyl) selenosemicarbazide and 4-(p-methoxyphenyl)selenosemicarbazide However compounds of Formula I wherein R is a group -R (30-, i.e. the monacyl derivatives of the selenosemicarbazides may be prepared by reacting an equimolecular amount of a selenosemicarbazides with an acylating agent, for example an acid chloride or an acid anhydride; the reaction usually being carried out in an organic solvent at a low temperature.

The compounds of Formula I wherein one of R and R is a group NRqRg-CS6 where R and R are each hydrogen atoms or alkyl groups may be prepared by reacting a compound of the general Formula IV:

Rs (IV) where R; and R have the meanings assigned to them in Formula I, with hydrogen selenide.

The compounds of Formula II may be prepared by reacting a selenosemicarbazide with a dibasic acid chloride; the reaction usually being carried out in an organic solvent at a low temperature.

The production of the 1,2,4-triazole-3-selenols of (c) wherein there is attached to the S-carbon atom an alkyl, group comprises reacting a selenosemicarbazide of the general Formula V:

R25 so wherein each of R R and R is a hydrogen atom or two of them are hydrogen atoms and one of them is a group selected from alkyl, aryl and aralkyl, with an acid chloride of the general formula R COCI in the presence of a base or with an acid anhydride of the general formula R COOROR wherein R is an alkyl group and then ring closing this acyl derivative by heating it in the presence of an alkali metal salt of a weak acid for example an acetate or carbonate, or in the presence of an alkali metal hydroxide or an alkoxide.

The production of the 1,2,4-triazole-3-selenols of (0) wherein there is attached to the S-carbon atom a hydrogen atom or an alkyl group which comprises from 1 to 4 carbon atoms comprises reacting a selenosemicarbazide of the above general Formula V with a carboxylic acid of the general formula R COOH where R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, to form the acyl derivative of the selenosemicarbazide, and then ring closing this acyl derivative by heating it in the presence of an alkali metal salt of a weak acid, for example an acetate or carbonate, or in the presence of an alkali metal hydroxide or an alkoxide.

The production of the 1,2,4-triazole-3-selenols of (c) wherein there is attached to the S-carbon atom an hydroxy group comprises reacting a selenosemicarbazide of the above Formula V with an alkyloxy-, aryloxyor aralkyloxy-haloformate in the presence of a base to form the alkoxy-, aryloxyor aralkoxycarbonyl derivative of the selenosemicarbazide and ring closing this compound in the presence of an alkali metal salt of a weak acid or in the presence of an alkali metal hydroxide or alkoxide,

with the elimination of the appropriate alcohol or phenol.

The production of the 1,2,4-triazole-3-selenols of (c) wherein there is attached to the S-carbon atom an amino, alkylamino, arylamino or aralkylamino group comprises reacting a selenosemicarbazide of the general Formula VI:

SeCHa lllaa Ran SIG R N -NN( J-NHR40 wherein R is a hydrogen atom or an alkyl, aryl or aralkyl group and each of R R and R is a hydrogen atom or two of them are hydrogen atoms and the third is a group selected from alkyl, aryl and aralkyl, with an alkali metal hydroxide to effect ring closure and separating the desired product.

Selenosemicarbazides of general Formula VI may be prepared by reacting a bis-selenourea with a one molecular proportion of a methylating agent in a basic medium.

The production of the bis-1,2,4-triazole-selenols may be effected by reacting a selenosemicarbazide with a dibasic acid chloride in the presence of a base to form the acyl derivative and then ring closing the acyl derivative by heating it in a basic medium e.g. in the presence of an alkali metal carbonate, hydroxide or ethoxide.

The bleach-fix accelerators of use in the present invention are preferably added to the beach-fix bath but they may be present during the bleach-fixing treatment adsorbed to or absorbed in the colour photographic material. In the processing of conventional colour photographic material, i.e. colour negative or colour reversal material bleach-fix accelerators of use in the present invention may be present in any treatment bath or wash bath which is used in the colour development process between the development step and the bleach-fix step. Exemplary of such baths are stop baths and stop-fix baths. The bleach-fix accelerators should not be present, however, in the developing solution as they interfere with the development of the colour material. For the same reason the bleach-fix accelerators of use in the present invention should not be present initially in the photographic material.

In the processing of silver-dye-bleach material the bleach-fix accelerators may be present in the wash bath which succeeds the dye-bleach treatment bath and precedes the bleach-fix bath but the bleach-fix accelerators should not be present during the dye-bleach treatment as they can interfere with this treatment step. Thus the bleachfix accelerators should not be present initially in the silverdye-bleach photographic material.

According to another embodiment of the present invention there is provided a stable-bleach-fix bath which comprises an aqueous solution of a mild oxidising agent, as hereinbefore defined, a silver halide solvent which is either a water-soluble thiosulphate or a water-soluble thiocyanate and a bleach-fix accelerator which is either a selenosemicarbazide of the above Formula I or a compound of the above Formula II, or a 1,2,4-triazole-3-selenol of the type (c) as hereinbefore defined, or a bis-1,2,4- triazole-B-selenol of the type (d) as hereinbefore defined.

Preferably in this aspect of the invention the mild oxidising agent is a ferric chelate complex or a diaquotetrammine-cobalt (III) complex.

It is preferred that the concentration of the bleach-fix accelerators of the type (a), (b), (c) or (d) as hereinbefore defined present in the bleach-fix bath is greater than 1 mg. per litre of bleach-fix bath. The most preferred amount being mg. of bleach-fix accelerator per litre of bleach-fix bath.

It is preferred that the concentration of the bleach-fix accelerators of the type (a), (b), (c) or (d) as hereinbefore defined present in a stop bath or a stop-fix bath or in a wash bath is greater than 1 mg. per litre of the solution.

The following examples will serve to illustrate the invention.

In the examples which follow the following bleach-fix accelerators were used: I

In the examples which follow a colour negative film was used which was made up as follows:

Layer order and Silver coating weight in sensitivity: mg. of Ag/decimetre 2 Nonstress Blue sensitive 13.4 Colloidal silver filler layer Green sensitive topcoat 13.1 Intralayer Green sensitive subcoat 16.0

Interlayer Red sensitive topcoat 17.5 Red sensitive subcoat 13.6 Base of cellulose triacetate Total 73.6

In this film:

the blue sensitive layer contained yellow colour coupler of the formula:

CmHu-N-CH:

the green sensitive layers each contained a magenta colour coupler of the formula:

CHzOCOCzHE the red sensitive layers each contained a cyan colour coupier of the formula:

@(jCONH- The following processing solutions were used in Examples 1-4 STOP-FIX Sodium thiosulphate pentahydrate g 171 Sodium acetate anhydrous g 31.4 Sodium sulphite anhydrous g 4.3 Acetic acid glacial ml 35 Potassium alum g 17.0 Ammonium chloride g 43 Water to 1 litre.

BLEACH-FIX Disodium tetraborate decahydrate g 12.5 Boric acid g 22.5 Sodium hydroxide -g 10.0 Ethylenediamine tetraacetic acid g 16.2 Disodium salt of ethylenediamine tetraacetic acid g 3.5- Ferric chloride (60% W./v. solution) ml 15.0 Sodium thiosulphate pentehydrate -g 95 Sodium sulphite anhydrous g 4- Water to 1 litre.

CONDITIONER Disodium salt of ethylene diamine tetraacetic acid g 0.50 Sodium carbonate anhydrous g 4.5 Formaldehyde (40% w./v. solution) ml Lissapol N (8% w./v. solution) ml 1.7 Water to 1 litre.

All processing solutions and wash water were used at 75 F.

The constitution of the colour developing solutions used in the following examples was as follows:

COLOUR DEVELOPER A Sodium metaborate 53.3 Sodium hydroxide 2.0 Sodium sulphite anhydrous 3.9 Potassium bromide 0.70 Hydroxylamine sulphate 2.34 Sodium sulphate anhydrous 7.8 4 amino N ethyl N (,B-hydroxy butyl)-aniline sulphate 6.0 Water to 1 litre.

COLOUR DEVELOPER B Sodium metaborate 80 Sodium sulphite anhydrous 2.0 Potassium bromide 1.0 Hydroxylamine sulphate 2.6 4-amino-N-ethyl N (fl-hydroxy ethyl)-aniline sulphate 4.6

Water to 1 litre.

EXAMPLES Pieces of the colour negative film were fogged and processed in a number of processing sequences all containing the use of a bleach-fix bath. The metallic silver remaining in the film at the end of each processing sequence was measured by analysis and expressed in mg. of Ag/decimetre When the bleach-fix bath or stop-fix bath contained one of the specified bleach-fix accelerators a reduction in the amount of residual silver resulted. In the examples the residual silver resulting when one of the accelerators was used is expressed as a percentage of that obtained when no accelerator was used (referred to as the control).

Example 1 Pieces of the colour negative film Were processed as follows:

Minutes Colour developer B 10 Stop-fix 4 Wash 4 Bleach-fix 6 Wash 4 Conditioner 4 Wash 4 Dry.

1 With and without accelerator.

The silver content of the pieces of film was analysed with the following results:

Pieces of the colour negative film were processed as follows:

Minutes Colour developer B 10 Stop-fix 4 Wash 4 Bleach-fix 6 Conditioner 4 Wash 4 Dry.

1 With and without accelerator.

TABLE 2 Concentration Residual of accelerator silver Accelerator in stop-fix bath, as percent compound N0. mg./litre of control Example 3 Pieces of the colour negative film were processed as follows:

Minutes Colour developer A 6 Stop-fix 4 Wash 4 Wash 4 Bleach-fix 6 Conditioner 4 Wash 4 Dry.

1 With and without accelerator.

TABLE 3 Concentration Residual of accelerator silver Accelerator in bleach-fix as percent compound No. bath, mg.llitre of control Example 4 Pieces of the colour negative film were processed as follows:

Minutes Colour developer B l Stop-fix 4 Bleach-fix 6 Wash 4 Conditioner 4 Wash 4 Dry.

1 With and without accelerator.

A positive tripack colour material intended for the silver dye-bleach system comprising silver halide emulsions containing bleachable azo-dyes Cibachrome manufactured by Ciba-Geigy A.G. of Switzerland was given a neutral wedge exposure and processed, the processing sequence being as follows:

Development: minutes p-Methyl-aminophenol-sulphate Sodium sulphite anhydrous Sodium carbonate anhydrous Potassium bromide Water to 1 litre.

Stop-fix: 4 minutes Sodium thiosulphate pentahydrate g 200 Sodium sulphite anhydrous g 20 Water to 1 litre.

Wash: 8 minutes Dye-bleach: 20 minutes Sulphuric acid, 96% --ml 27.5 Potassium iodide g 10 Solution of 0.9 g. 2,B-dimethyl-G-aminquinoxaline in 50 ml. ethanol ml Water to 1 litre.

Wash: 4 minutes Bleach-fix: 6 minutes Disodium tetraborate decahydrate g 12.5 Boric acid g 22.5 Sodium hydroxide g 10.0 Ethylenediaminetetraacetic acid g 16.2 Disodium salt of ethylenediaminetetraacetic acid dihydrate g 3.5 Ferric chloride (60% w./v. solin.) ml 15 Sodium thiosulphate pentahydrate g 95.0 Sodium sulphite anhydrous g 4.0 Selenosemicarbazide rng Water to 1 litre.

Wash: 8 minutes Dry The processed material was satisfactory and substantially no residual silver was left in the material even in the areas of high exposure. Similar silver-dye-bleach material was exposed and processed using the same solutions as set forth above except that the bleach-fix solution contained no selenosemicarbazide. Even when the material had been treated in the bleach-fix bath for 25 minutes it was unsatisfactory because it had a high minimal density due to the incomplete removal of the residual silver in the areas of high exposure.

What We claim is:

1. In the processing of photographic material comprising exposed and developed silver halide emulsion layers to yield material having colour dye images therein the step of treating the exposed and developed photographic material with a stable bleach-fix bath which comprises an aqueous solution of a mild oxidising agent which is strong enough to bleach the silver but not strong enough to oxidise silver halide solvents and a silver halide solvent which is either a water-soluble thiosulphate or a Water-soluble thiocyanate in the presence of a bleach-fix accelerator which is selected from (a) a water-soluble 'selenosemicarbazide of the general formula:

wherein one of R and R is a hydrogen atom or an alkyl, aralkyl or aryl group or a group R CO where R is a hydrogen atom or an alkyl, alkoxy or heterocyclic group, or a group NR R CSe- Where R and R are each hydrogen atoms or alkyl groups and the other of R and R is a hydrogen atom or an alkyl group, R is a hydrogen atom or an alkyl, aralkyl or aryl group, one of R and R is a hydrogen atom or an alkyl, aralkyl or aryl group and the other of R and R is a hydrogen atom or an alkyl group, at least one of R R or R being a hydrogen atom and there being not more than one group selected from aryl, aralkyl and heterocyclic present in the compound or (b) a Water-soluble compound of the general formula:

wherein each of R -R is a hydrogen atom or an alkyl group there being not more than four alkyl substituent groups in the compound and at least one of R R R R14, R and R being a hydrogen atom and X is a -(CH2)m linkage group wherein m is 0 to 4, or (c) a water-soluble 1,2,4-triazole-3-solenol wherein the S-carbon atom car-1 ries a substituent selected from a hydrogen atom or an alkyl, hydroxy, amino, alkylamino, arylamino or aralkylamino group and one of the nitrogen atoms carries a substituent selected from a hydrogen atom or an alkyl, aralkyl or aryl group, or (d) a water-soluble 5,5-bis-1,2,4-tri- 1 1 azolo-3-selenol wherein the triazole rings are linked directly or via a link 2)n' wherein n is 1-4 and wherein one nitrogen atom in each of the triazole rings carries a substituent selected from a hydrogen atom and an alkyl, aryl and aralkyl group.

2. A process according to claim 1 wherein the bleachfix accelerator is a compound of the formula set forth first in claim 1 wherein each of R R R R and R is a hydrogen atom.

3. A process according to claim 1 wherein the bleachfix accelerator is a water-soluble 1,2,4-triazole-3 selenol wherein the 5 carbon atom carries a hydrogen atom or an hydroxy group and one of the nitrogen atoms carries a hydrogen atom.

4. In a colour development process for the production of the coloured image in exposed colour silver halide photographic material after the development step, the step of treating the exposed and developed photographic material with an aqueous solution of a bleach-fix accelerator which is a water-soluble selenosemicarbazide of the general formula:

wherein R is a hydrogen atom or an alkyl, aralkyl or aryl group or a group R CO- wherein R is a hydrogen atom or an alkyl, aralkyl, aryl or heterocyclic group, or

is a water soluble 1,2,4-triazole-3-selenol of the general formula:

Ra-C l-86H wherein R is a hydrogen atom or an alkyl group and simultaneously or subsequently treating the photographic material in a stable bleach-fix bath which comprises an aqueous solution of a mild oxidising agent which is strong enough to bleach the silver but not strong enough to oxidise silver halide solvents and a silver halide solvent which is either a water-soluble thiosulphate or a watersoluble thiocyanate.

5. A process according to claim 1 wherein the mild oxidising agent is a ferric chelate complex.

6. A process according to claim 5 wherein the ferric chelate complex is a ferric ethylenediaminetetraacetic acid complex.

7. A process according claim 1 wherein the bleach-fix accelerator is present in the bleach-fix bath.

8. A stable bleach-fix bath which comprises an aqueous solution of a mild oxidising agent which is strong enough to bleach the silver but not strong enough to oxidise silver halide solvents, a silver halide solvent which is either a water-soluble thiosulphate or a water-soluble thiocyanate and a bleach-fix accelerator which is selected from (a) a water-soluble selenosementcarbazide of the general formula:

R3 Se l l NN --N\ R2 R5 wherein one of R and R is a hydrogen atom or an alkyl, aralkyl or aryl group or a group R CO where R is a hydrogen atom or an alkyl, alkoxy or heterocyclic group, or a group NR R -CSe-- where R and R are each hydrogen atoms or alkyl groups and the other of R and R is a hydrogen atom or an alkyl group, R is a hydrogen atom or an alkyl, aralkyl or aryl group, one of R and R is a hydrogen atom or an alkyl, aralkyl or aryl group and the other of R and R is a hydrogen atom or an alkyl group, at least one of R R or R being a hydrogen atom and there being not more than one group selected from aryl, aralkyl and heterocyclic present in the compound or (b) a water-soluble compound of the general formula:

wherein each of R -R is a hydrogen atom or an alkyl group there being not more than four alkyl substituent groups in the compound and at least one of R R R R R and R being a hydrobgen atom and X is a (CH7) ln' linkage group wherein m is 0 to 4, or (c) a water-soluble 1,2,4-triazole-3-selenol wherein the S-carbon atom carries a substituent selected from a hydrogen atom or an alkyl, hydroxy, amino, alkylamino, arylamino or aralkylarnino group and one of the nitrogen atoms carries a substituent selected from a hydrogen atom or an alkyl, aralkyl or aryl group, or (d) a water-soluble 5,5-bisl,2,4-triazole-3- selenol wherein the triazole rings are linked directly or via a link wherein n is l--4 and wherein one nitrogen atom in each of the triazole rings carries a substituent selected from a hydrogen atom and an alkyl, aryl and aralkyl group.

9. A stable bleach-fix bath according to claim 8 wherein the mild oxidising agent is a ferric chelate complex or a diaquotetramine-cobalt (III) complex.

10. A stable bleach-fix bath according to claim 8 wherein the concentration of bleach-fix accelerator of type (a), (b), (c) or (d) is greater than 1 mg. per litre of bleachfix bath.

11. A stop-fix bath which comprises an aqueous acid solution of a silver-halide solvent selected from a watersoluble thiosulphate and a water-soluble thiocyanate and a water-soluble bleach-fix accelerator which is selected from (a) a water-soluble selenosemicarbazide of the general formula:

wherein one of R and R is a hydrogen atom or an alkyl, aralkyl or aryl group or a group R CO- where R is a hydrogen atom or an alkyl, alkoxy or heterocyclic group, or a group NR R -CSewhere R and R are each hydrogen atoms or alkyl groups and the other of R and R is a hydrogen atom or an alkyl group, R 3 is a hydrogengen atom or an alkyl, aralkyl or aryl group, one of R and R is a hydrogen atom or an alkyl, aralkyl or aryl group and the other of R and R is a hydrogen atom or an alkyl group, at least one of R R or R being a hydrgen atom and there being not more than one group selected from aryl, aralkyl and heterocyclic present in the compound or (b) a water-soluble compound of the general formula:

wherein each of R -R is a hydrogen atom or an alkyl group there being not more than four alkyl substituent groups in the compound and at least one of R R R R R and R being a hydrogen atom and X is a linkage group wherein m is 0 to 4, or (c) a water-soluble 1,2,4-triazole-3-selenol wherein the S-carbon atom carries a substituent selected from a hydrogen atom or an alkyl, hydroxy, amino, alkylamino, arylamino or aralkylamino group and one of the nitrogen atoms carries a substituent selected from a hydrogen atom or an alkyl, aralkyl or aryl group, or (d) a water-soluble 5,5-bis-1,2,4-tri- 13 azole-3-selenol wherein the triazole rings are linked directly or via a link wherein n is 1-4 and wherein one nitrogen atom in each of the triazole rings carries a substituent selected from a hydrogen atom and an alkyl, aryl and aralkyl group.

12. In the processing of exposed and developed photographic material comprising silver halide emulsion layers to yield material having colour dye images therein, the step of treating the exposed and developed photographic material with a stable bleach-fix bath which comprises an aqueous solution of a mild oxidising agent which is strong enough to bleach the silver but not strong enough to oxidise silver halide solvents and a silver halide solvent which is either a water-soluble thiosulphate or a watersoluble thiocyanate in the presence of a bleach-fix accelerator which is selected from the group consisting of 3-selenosemicarbazide; l-formyl-3-selenosernicarbazide; 1-acetyl-3-selenosemicarbazide; 1-propionyl-3-selenosemicarbazide; 2-methyl-3-selenosemicarbazide; 4-methyl-3-selenosemicarbazide; 1,1'-dimethyl-3-selenosemicarbazide; 1,2-dimethy1-3-selenosemicarbazide; 1,2,4-trimethyl-3-selenosemicarbazide; 1,1,4-trimethyl-3-selenosemicarbazide; 1-acetyl-4-methyl-3-selenosemicarbazide; 1-acetyl-4-benzyl-3-selenosemicarbazide; 4-benzyl-3-selenosemicarbazide; 1phenyl-3-selenosemicarbazide; 2-phenyl-3-selenosernicarbazide; 4-phenyl-3-selenosemicarbazide; 2-rnethyl-4-phenyl-3-selenosemicarbazide; 1-(2-furoyl)-3-selenosemicarbazide; 1,1-oxalyl-bis (3-selenosemicarbazide) 1,2,4-triazole-3-selenol; S-methyl-1,2,4-triazole-3-selenol; 4,5-dimethyl-1,2,4-triazole-3selenol; 5,5-bis(1,2,4-triazole-3-selenol) 5,5 '-methylene-bis( 1,2,4-triazole-3-selenol) 5,5 -ethylene-bis( 1,2,4-triazole-3-seleno1) and 1-eth0xycarbonyl-3-selenosernicarbazide.

13. A process for the production of photographic material having colour dye images therein from exposed and developed photographic material comprising silver halide emulsion layers and including the step of treating the exposed and developed photographic material with a stable bleach-fix bath in the presence of a bleach-fix accelerator selected from the group consisting of 1 4 4-benzyl-3-selenosemicarbazide; 1-phenyl-3-selenosemicarbazide; 2-phenyl-3-selenosernicarbazide; 4-phenyl-3-selenosemicarbazide; Z-methyl-4-pheny1-3-selenosemicarbazide; 1-( 2-furoyl)-3selenosemicarbazide; l,1'-oxalyl-bis(3-selenosemicarbazide) 1,2,4-triazole-3-selenol; S-methyl-l,2,4-triazole-3-selenol; 4,5-dimethyl-l,2,4-triazole-3-selenol;

5 ,5 '-bis( 1,2,4-triaZole-3-selenol);

5 ,5 -metl1ylene-bis( 1,2,4-triazole-3-selenol) 5 ,5 -ethylene-bis( 1,2,4-triaZole-3-selenol) and 1-ethoxycarbonyl-3-selenosemicarbazide.

14. A stable bleach-fix bath which comprises an aqueous solution of a mild oxidising agent which is strong enough to bleach the silver but not strong enough to oxidise silver halide solvents, a silver halide solvent which is either a water-soluble thiosulphate or a water-soluble thiocyanate and a bleach-fix accelerator which is selected from the group consisting of 3-selenosemicarbazide; 1-formyl-3-selenosemicarbazide; 1-acetyl-3-selenosemicarbazide; 1-propionyl-3-selenosemicarbazide; 2-methyl-3-selenosemicarbazide; 4-methyl-3-selenosemicarbazide; 1,1'-dimethyl-3-selenosernicarbazide; l,Z-dimethyl-3-selenosernicarbazide; 1,2,4-trimethyl-3-selenosemicarbazide; 1,1',4-trimethyl-3-selenosemicarbazide; 1-acetyl-4-methyl-3-selenosemicarbazide; 1-acetyl-4-benzyl-3-selenosemicarbazide; 4-benzyl-3-selenosemicarbazide; 1-phenyl-3-selenosemicarbazide; 2-phenyl-3-selenosemicarb azide; 4-pl1enyl-3-selenosemicarbazide; 2-methyl-4-phenyl-3-selenosemicarbazide; 1- (2-furoyl)-3-selenosemicarbazide; l,1-oxalyl-bis(3-selenosemicarbazide) 1,2,4-triazole-3-selenol; S-methyl-l,2,4-triazole-3-selenol; 4,5-dimethyl-1,2,4-triazole-3-selenol;

5 ,5 'bis 1,2,4-triazole-3-selenol) 5,5 '-methylene-bis( 1,2,4-triazole-3-selenol); 5 ,5 '-ethylene-bis( 1,2,4-triazole-3-selenol) and 1-ethoxycarbonyl-3-selenosemicarbazide.

References Cited UNITED STATES PATENTS 2,131,038 9/1938 Brooker 96-109 2,410,690 11/1946 Smith 96-663 3,396,017 8/1968 Bacon 96-63 3,619,188 11/1971 Alcock 96-60 NORMAN G. TORCHIN, Primary Examiner I. R. HIGHTOWER, Assistant Examiner US. Cl. X.R.

96-60 R, 60 BF, 61 R, 62