Method for developing an exposed photographic silver halide emulsion material

Abstract

 A method for developing an exposed photographic silver halide emulsion material with reduced sludge deposition including the step of treating said material with an aqueous alkaline liquid in the presence of (i) a developing agent, (ii) a heterocyclic mercapto compound and (iii) a surface active agent being an anionic alkylphenoxy polyalkyleneoxy phosphate ester surfactant, and wherein the mercapto compound is a heterocyclic mercapto compound corresponding to the following tautomeric general formulae (A) and (B):

wherein :
Z represents the necessary atoms to close a 5- or 6-membered heterocyclic nitrogen containing ring and includes a hydrocarbon group of at least 7 carbon atoms in straight line.

Description

[0001] The present invention relates to a method for developing an exposed photographic silver halide emulsion material and a liquid used therein by means of which the formation of silver sludge is effectively reduced.It is known that finely divided metallic silver, so-called silver sludge, is formed in the developer (ref. e.g. Photographic Silver Halide Diffusion Processes by A.Rott and E.Weyde - The Focal Press, (1972), p. 67). The formation of silver sludge is particularly disturbing in automatic processing apparatus wherein it results in deposits of black silver on conveyor and transport rollers and smudging of photographic material conducted therewith.

[0002] In order to prevent the formation of silver sludge it has been proposed to add particular compounds forming sparingly soluble and non-­reducible silver salts to the developer, e.g. 5,5′-bis-1,2,4-triazolin-3-­thiones or derivatives of 1,3,4-thiadiazole-2-thiols as described, e.g. in BE-P 606,550 and GB-P 1,120,963, 2-mercapto-1,3,4-thiadiazoles described in US-P 3,212,892, a great variety of other mercapto compounds described in FR-P 1,470,235 and 1-phenyl-5-mercapto-tetrazole compounds having a -NHX substituent on the phenyl nucleus as described in GB-P 1, 471,554. In the latter document it has been described that the emulsion layer may contain auxiliary coating agents such as saponin, sodium lauryl sulphate, dodecylphenol polyethylene oxide ether and hexadecyltrimethyl ammonium bromide.

[0003] It is generally known that even small amounts of 1-phenyl-5-­mercaptotetrazole are highly effective in preventing fog.

[0004] It has been found experimentally by us that when in the developer liquid 1-phenyl-5-mercaptotetrazole is used for anti-sludge purposes in an amount higher than necessary for reducing fog the photographic sensitivity, i.e. speed is markedly reduced. Such is probably due to the penetrating of the 1-phenyl-5-mercaptotetrazole from the developer liquid into the exposed photographic silver halide emulsion layer and its interaction with latent image nuclei.

[0005] It is an object of the present invention to provide a method for developing a photographic silver halide emulsion material wherein the formation of silver sludge is reduced effectively without adversely affecting photographic speed.

[0006] It is another object of the present invention to provide an aqueous alkaline liquid for use in the development of an exposed photographic silver halide emulsion material and by means of which the formation of silver sludge is reduced effectively without adversely affecting the photographic speed of the silver halide emulsion material.

[0007] Other objects and advantages of the present invention will become clear from the further description.

[0008] In accordance with the present invention a method for developing an exposed photographic silver halide emulsion material is provided, wherein said method comprises the treating of said material with an aqueous alkaline liquid in the presence of (i) a developing agent, (ii) a heterocyclic mercapto compound including an aliphatic group of at least 3 carbon atoms and (iii) a surface active agent, characterized in that said surface active agent is an anionic alkylphenoxy polyalkyleneoxy phosphate ester surfactant, and the mercapto compound is a heterocyclic mercapto compound corresponding to the following tautomeric general formulae (A) and (B):

wherein :
Z represents the necessary atoms to close a 5- or 6-membered heterocyclic nitrogen containing ring and includes a hydrocarbon group of at least 7 carbon atoms in straight line.

[0009] The said anionic surfactant is preferably an alkylphenoxy(ethyleneoxy)_n phosphoric acid mono- and/or di-ester compound in salt form, e.g. sodium salt, wherein n is a positive integer of at least 4, e.g. n is 4 to 25, and the alkyl group is a C8 to C20 alkyl group.

[0010] Heterocyclic mercapto-compounds that are within the scope of said general formulae (A) and (B) belong e.g. to the classes of mercapto­tetrazoles, mercapto-triazoles, mercapto-thiadiazoles, mercapto­oxadiazoles, mercapto-benzimidazoles, mercapto-benzoxazoles and mercapto­benzthiazoles.

[0011] Preferred mercapto-tetrazoles correspond to the following general formula :

wherein:
R represents a substituent comprising a hydrocarbon chain containing at least 7 C-atoms in straight line, preferably at least 9 C-atoms in straight line.

[0012] Examples of 1-phenyl-5-mercaptotetrazole compounds suited for use according to the present invention are listed in the following Table 1.

[0013] Other suitable heterocyclic mercapto or thione compounds according to general formulae (A) and (B) are listed in the following Table 2.

[0014] Compound 13 of the above Table 2 can be prepared starting from n-hexadecylisothiocyanate and sodium azide in a mixture of dioxan and water.

[0015] Compounds 14 and 15 of the above Table 2 can be prepared by a condensation reaction using the corresponding amino-phenyl-5-mercapto-­tetrazole compounds and acid chlorides.

[0016] By the presence of the long chain R group (at least 7-C in straight line) in the mercapto compounds there is almost no diffusion of these compounds from the processing liquid into the hydrophilic silver halide gelatin emulsion layer(s) of the photographic material and no interaction with the latent silver image resulting in a lowering of the photographic speed can take place.

[0017] The preparation of anionic alkylphenoxy polyoxyalkylene phosphoric acid mono- and/or diester surfactants is described e.g. in the book Anionic Surfactants, part II, edited by Warner M. Linfield, Marcel Dekker Inc. - New York and Basel, 509-511 (1976). Alkylphenoxy polyalkyleneoxy mono- and diester phosphates are commercially available under the trade name GAFAC, e.g. GAFAC RM-710, of Antara Chemicals-General Aniline & Film Corporation, New York - USA (see Chem. Eng. News 40 (1962) No. 16, p. 87).

[0018] The liquid according to the present invention for use in the development of a photo-exposed photographic silver halide emulsion material is an aqueous alkaline liquid containing a heterocyclic mercapto compound including an aliphatic group of at least 3 carbon atoms and a surface active agent, characterized in that said surface active agent is an anionic alkylphenoxy polyalkyleneoxy phosphate ester surfactant, and the mercapto compound is a heterocyclic mercapto compound corresponding to the following tautomeric general formulae (A) and (B):

wherein :
Z represents the necessary atoms to close a 5- or 6-membered heterocyclic nitrogen containing ring and includes a hydrocarbon group of at least 7 carbon atoms in straight line.

[0019] Said liquid used for the development of a photo-exposed photographic silver halide emulsion material does not necessarily contain a developing agent before its use since the developing agent(s) may be present already in the photographic material. In that case the liquid is called an activator liquid.

[0020] In a developer or activator liquid according to the present invention the mercapto compound (ii) is present preferably in an amount of from 10⁻⁴ to 10⁻³ mole per liter and the surface active agent (iii) is present in said liquid preferably in an amount of 50 mg to 200 mg per liter.

[0021] According to a particular embodiment the surfactant (iii) is applied in the photographic material in a water-permeable layer wherefrom it can diffuse into the developing liquid. For example, the surface active agent (iii) is present in a hydrophilic colloid layer of the photographic material at the rear side of its support with respect to the photographic silver halide emulsion layer(s), e.g. in an anti-curl or anti-halation layer. A suitable coverage of surface active agent (iii) in the photographic material is e.g. in the range of 0.01 to 0.20 g per m2.

[0022] The developer liquid may contain any type of developing agent known for use in the development of exposed photographic silver halide. For example as developer compounds may be utilized hydroquinone, p-methylaminophenol, 1-phenyl-3-pyrazolidinone, p-phenylene diamine derivatives and the like. The developer may contain antioxidants such as alkali-metal sulphites, bisulphites, metasulphites or metahydrogen sulphites. The developer solution can be alkalized with alkali-metal hydroxides, phosphates, borates, carbonates and the like. The developer liquid or activator liquid may contain still other ingredients, e.g. metal complexing agents, an anti-fogging agent, e.g. potassium bromide, a benzotriazole, a benzothiazole, a tetrazole, e.g. up to 0.03 g per liter of 1-phenyl-5-mercapto-tetrazole, solvents improving the dissolution of the developing agents, e.g. alcohols, polyethylene glycols and esters thereof and alkanolamines, surface active agents other than the above mentioned compound (iii), development retarding or activating compounds, e.g. quaternary ammonium salts, and gelatin hardening agents, e.g. dialdehyde compounds such as glutardialdehyde.

[0023] The pH of the alkaline activator or developer solution is generally in the range of 8.5 to 11.

[0024] The present invention includes the development by means of the above defined liquid of any type of photographic silver halide emulsion layer material, e.g. a graphic art and X-ray recording material.

[0025] The silver halide used in the silver halide emulsion layer(s) may be of any type or composition used in silver halide photography. The liquid according to the present invention may be applied in the development of black-and-white materials as well as in colour development. The development proceeds advantageously in conjunction with the silver halide complex diffusion transfer reversal process (DTR-process) described in detail in the already mentioned book of A.Rott and E.Weyde.

[0026] The development process according to the present invention is advantageously applied in automatic processing equipment containing conveyer rollers as described, e.g. in US-P 3,025,779 and 3,545,971.

[0027] In order to remove sludge that may be formed, e.g. in developing liquids wherein the mercapto-compound (ii) has reacted substantially with colloidal silver and has lost its activity a filter may be used wherethrough the liquid is pumped in a closed circuit.

[0028] A survey of filters and filter media is given by Kirk-Othmer in Encyclopedia of Chemical Technology, 3rd.ed. Vol. 10, (1980) - A Wiley­Interscience Publication - John Wiley & Sons, New York, p. 298-334.

[0029] Particular preference is given to a cartridge filter wherefrom the filter medium, e.g. cellulose yarn, can be removed from the filter housing and burned without leaving ashes. Such makes it much easier to separate the solid residue containing noble metal without interference with solid material the filter is made of.

[0030] It has been established in practice that filter media comprising a mercapto-compound (ii) as defined herein intercept colloidal noble metal even when the pores of the filter medium are rather large and by their diameter are not contributing to an absolute interception. By the consequence of the improved interception of the colloidal noble metal particles the flow-through speed or pump pressure may be increased so that larger volumes of liquid can be freed from noble metal within the same period of time.

[0031] The present invention is illustrated by the following example without, however, limiting it thereto. All ratios and percentages are by weight unless otherwise indicated.

EXAMPLE

[0032] Photosensitive paper sheet materials containing a silver halide emulsion layer incorporating silver bromoiodide grains (containing 99 mole % of bromide) at a coverage of 2.85 g per m2 expressed as silver nitrate were exposed through a graphic original so that about 10% of the total surface of each sheet material had been exposed. These sheet materials were developed in a developer containing the following ingredients in 1000 ml of demineralized water.
potassium carbonate            23.7 g
potassium sulphite             65.5 g
potassium bromide              10.0 g
potassium hydroxide             5.3 g
diethylene glycol              20  ml
hydroquinone                   20.0 g
1-phenyl-3-pyrazolidinone      0.48 g
1-phenyl-5-mercapto-tetrazole  30 mg
                               pH: 10.5

[0033] The development was carried out at 35 °C in a developer tank containing 24 liters of developer regenerated at a rate of 250 ml per h with fresh developer. The sheet materials were conveyed by rollers at a daily throughput of 30 m2 through the developer in a developing machine PAKO 24 S (trade name).

[0034] In comparison tests compounds I, II and III as described hereinafter were added to the alkaline developer liquid in the amounts given. The obtained results in the counteraction of sludge deposition being defined as m2 of photographic material passed through the developing machine before visual appearance of a black deposit on the white area of the photographic material are listed in Table 3. In that Table 3 also fog values and sensitivity values (photographic speed values) obtained before detectable sludge deposition are listed.

[0035] The speed values defined as log exposure values at optical density 1.00 above fog were expressed as percentual values with respect to the speed 100 given arbitrarily to the result obtained in Test 1.

[0036] The fog values are the optical density values in the non-exposed area.

[0037] From the obtained results can be learned that there is a superadditive effect in the counteraction of sludge by using in the developer liquid according to the present invention the combination of compounds I and II which combination does not result in a loss of speed.

[0038] Compound I is compound 3 of Table 1.
Compound II is an equimolar mixture of alkylphenoxy(CH₂-CH₂-O)_n-PO-(OH)₂ and [alkylphenoxy(CH₂-CH₂-O)_n)]₂-PO-OH, wherein the alkyl group is a n-hexadecyl group and n is 15.
Compound III is 1-phenyl-5-mercaptotetrazole.

[0039] In test 2 the developer liquid was completely free of 1-phenyl-5­mercapto-tetrazole.

[0040] In replacing compound II in the above test 4 by a C8-­alkylphenoxy(CH₂-CH₂-O)_n-PO-(OH)₂ compound having n = 4 a still valuable anti-sludge activity without drop in sensitivity was obtained.

Claims

1. A method for developing an exposed photographic silver halide emulsion material, wherein said method comprises the treating of said material with an aqueous alkaline liquid in the presence of (i) a developing agent, (ii) a heterocyclic mercapto compound including an aliphatic group of at least 3 carbon atoms and (iii) a surface active agent, characterized in that said surface active agent is an anionic alkylphenoxy polyalkyleneoxy phosphate ester surfactant, and the mercapto compound is a heterocyclic mercapto compound corresponding to the following tautomeric general formulae (A) and (B):

wherein :
Z represents the necessary atoms to close a 5- or 6-membered heterocyclic nitrogen containing ring and includes a hydrocarbon group of at least 7 carbon atoms in straight line.

2. A method according to claim 1, wherein the heterocyclic mercapto compound is selected from the group of mercapto-tetrazoles, mercapto-­triazoles, mercapto-thiadiazoles, mercapto-oxadiazoles, mercapto-­benzimidazoles, mercapto-benzoxazoles and mercapto-benzthiazoles.

3. A method according to claim 1 or 2, wherein the heterocyclic mercapto compound is a mercapto-tetrazole corresponding to the following general formula :

wherein:
R represents a substituent comprising a hydrocarbon chain containing at least 7 C-atoms in straight line.

4. A method according to any of claims 1 to 3, wherein the anionic surfactant is an alkylphenoxy(ethyleneoxy)_n phosphoric acid mono- or di-ester compound in salt form, wherein n is a positive integer of at least 4, and the alkyl group is a C8 to C20 alkyl group.

5. A method according to any of the preceding claims, wherein said compound (ii) is used in the aqueous alkaline liquid in an amount of from 10⁻⁴ to 10⁻³ mole per liter.

6. A method according to any of the preceding claims, wherein the compound (iii) is used in the aqueous alkaline liquid in an amount of from 50 to 200 mg per liter.

7. A method according to any of the preceding claims, wherein the treating is carried out in the presence of an anti-fogging agent.

8. A method according to any of the claims 1 to 5, wherein the exposed photographic material contains in a water-permeable layer already before exposure said compound (iii).

9. Aqueous alkaline developer or activator liquid for use in the development of a photo-exposed photographic silver halide emulsion material containing a heterocyclic mercapto compound including an aliphatic group of at least 3 carbon atoms and a surface active agent, characterized in that said surface active agent is an anionic alkylphenoxy polyalkyleneoxy phosphate ester surfactant, and the mercapto compound is a heterocyclic mercapto compound corresponding to the following tautomeric general formulae (A) and (B):

wherein :
Z represents the necessary atoms to close a 5- or 6-membered heterocyclic nitrogen containing ring and includes a hydrocarbon group of at least 7 carbon atoms in straight line.

10. A liquid according to claim 9, wherein the heterocyclic mercapto compound is selected from the group of mercapto-tetrazoles, mercapto-triazoles, mercapto-thiadiazoles, mercapto-oxadiazoles, mercapto-­benzimidazoles, mercapto-benzoxazoles and mercapto-benzthiazoles.

11. A liquid according to claim 9 or 10, wherein the heterocyclic mercapto compound is a mercapto-tetrazole corresponding to the following general formula :

wherein:
R represents a substituent comprising a hydrocarbon chain containing at least 7 C-atoms in straight line.

12. A liquid according to any of claims 9 to 11, wherein the anionic surface active agent is an alkylphenoxy(ethyleneoxy)_n phosphoric acid mono- or di-ester compound in salt form, wherein n is a positive integer of at least 4, and the alkyl group is a C8 to C20 alkyl group.

13. A liquid according to any of claims 9 to 12, wherein said mercapto compound is present in an amount of from 10⁻⁴ to 10⁻³ mole per liter.

14. A liquid according to any of claims 9 to 13, wherein said surface active agent is present in an amount of from 50 to 200 mg per liter.

15. A liquid according to any of the claims 9 to 14, wherein the liquid contains an anti-fogging agent.