Developer compositions for silver halide photographic materials

Abstract

 Developer compositions for silver halide photographic materials having an improved resistance to air oxidation. even if in the presence of metal ion traces, comprise the following principal constituents:

a) hydroquinone or a substituted hydroquinone;

b) an auxiliary superadditive developing agent.

c) an alkali metal sulfite;

d) an organic antifoggant agent;

e) inorganic alkali agents;

f) an alkanolamine; and

g) a sequestering agent selected in the group of diethylenetetraminepentacetic acid, 1,3-diamino-2-propanoltetracetic acid and 1-hydroxyethylidene-1.1'- diphosphonic acid.

Description

Field Of The Invention

[0001] The present invention relates to developer compositions for silver halide photographic materials and, particularly, to photographic silver halide developer compositions having improved resistance to aerial oxidation.

Background Of The Art

[0002] In general, treatment of black and white silver halide photographic materials is carried out in the order of development, stopping, fixing and washing.

[0003] Development is ordinarily carried out with alkaline developers containing hydroquinone as a developing agent and alkali metal sulfite as a preservative. Such developers tend to be oxidized by the air during preparation, working and storage. It is a well-known phenomenon that traces of certain metal ions, such as copper and iron, have a catalytic effect on the aerial oxidation of developers (the metal ions may have been introduced as an impurity into the water or into the chemicals used to compound the developing solution).

[0004] Some compounds have been proposed to reduce or eliminate the catalytic effect of such metal ions, especially iron, on the aerial oxidation of developers by forming very stable complexes with said metal ions in alkaline solution, but their activity is reduced to a high degree when silver halide photographic materials are treated in continuous transport processing machines, especially at high temperatures. In that case, considerable quantities of air are introduced into developer solutions used in processing machines, this aeration oxidizing more of the developing agent than the real development process itself, causing a rapid degradation of the developer.

Summary Of The Invention

[0005] A developer composition for silver halide photographic materials has been found which has improved resistance to air oxidation, even in the presence of metal ion traces. The composition can be left in continuous transport processing machines for several days, said developer compositions having the following constituents:

(a) hydroquinone or a substituted hydroquinone,

(b) an auxiliary superadditive developing agent,

(c) an alkali metal sulfite,

(d) an organic-antifoggant agent,

(e) inorganic alkali agents,

(f) an alkanolamine, and

(g) a sequestering agent selected in the group of diethylenetetraminepentacetic acid (hereinafter referred to as DTPA), 1,3-diamino-2-propanoltetracetic acid (hereinafter referred to as DTPA) and 1-hydroxyethylidene-1,1'-diphosphonic acid (hereinafetr referred to as HEDP).

Detailed Description Of The Invention

[0006] The present invention relates to a developer composition for silver halide photographic materials comprising hydroquinone or a substituted hydroquinone, an alkali metal sulfite, an organic antifoggant agent and inorganic alkali agents, characterized by further comprising an alkanolamine and a sequestering agent selected in the group of DTPA, DPTA and HEDP.

[0007] Preferably, the above described developer composition comprises an additional compound selected in the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid.

[0008] More preferably, the developer composition above comprises an auxiliary developing agent selected from the class of substituted pyrazolidone and p-aminophenol compounds.

[0009] Still more preferably, the organic antifoggant agent is selected from the group of mixtures of 5-nitroindazole and benzimidazole nitrate, 5-nitrobenzotriazole and 1-phenyl-5-mercaptotetrazole, and benzotriazole and 1-phenyl-5-mercaptotetrazole and/or the alkanolamine is selected from the group of diethanolamine, triethanolamine, 2-benzylaminoethanol, 2-methylaminoethanol, 2-ethylaminoethanol and 2-isopropyl- aminoethanol.

[0010] In particular the present invention relates to a developer composition for silver halide photographic materials comprising:

(a) hydroquinone or a substituted hydroquinone in an amount from about 5 to 50, preferably 10 to 30 grams per liter;

(b) an auxiliary developing agent in an amount from about 0.1 to 15, preferably 0.2 to 5 grams per liter;

(c) an alkali metal sulfite in an amount from about 15 to 100, preferably 20 to 50 grams per liter;

(d) an alkanolamine in an amount from about 10 to 30, preferably 5 to 20 grams per liter;

(e) an organic antifoggant agent selected in the group of mixtures of 5-nitroindazole and benzimidazole nitrate, 5-nitrobenzotriazole and 1-phenyl-5-mercaptotetrazole, and benzotriazole and 1-phenyl-5-mercaptotetrazole, in an amount from about 0.1 to 3, preferably 0.2 to 1.5 grams per liter;

(f) a sequestering agent selected from the group of DTPA, DPTA and HEDP in an amount from about 5 to 50, preferably 10 to 30 grams per liter;

(g) a compound selected in the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid in an amount from about 5 to 100, preferably 15 to 50 grams per liter;

(h) inorganic alkali agents sufficient to provide a pH of at least 10 and

(i) water sufficient to make up 1 liter.

[0011] In another aspect the present invention relates to a single part concentrated developer composition for silver halide photographic materials, to be diluted with water and form a ready for use developer solution, comprising hydroquinone or a substituted hydroquinone, an alkali metal sulfite and inorganic alkali agents, characterized in that it contains an alkanolamine, an organic sequestering agent selected in the group of DTPA, DPTA and HEDP and a mixture of benzotriazole and 1-phenyl-5- mercaptotetrazole antifogging agents.

[0012] Preferably, the single part concentrated developer composition above further comprises a compound selected in the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid.

[0013] More preferably the single part concentrated developer composition above comprises an auxiliary developing agent selected from the class of substituted pyrazolidone and para-aminophenol compounds.

[0014] In particular the present invention relates to a single part concentrated developer composition for silver halide photographic materials, to be diluted with water and form a ready-for-use developer solution, comprising:

(a) hydroquinone or a substituted hydroquinone in an amount from about 40 to 120 grams per liter;

(b) an auxiliary developing agent in an amount from about 0.5 to 20 grams per liter;

(c) an alkali metal sulfite in an amount from about 80 to 200 grams per liter;

(d) an alkanolamine in an amout from about 40 to 120 grams per liter;

(e) a mixture of benzotriazole and 1-phenyl-5-mercaptotetrazole antifoggant agents in an amount from about 0.8 to 6 grams per liter;

(f) a sequestering agent selected in the group of DTPA, DPTA and HEDP in an amount from about 20 to 150 grams per liter;

(g) a compound selected in the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid, in an amount from about 50 to 150 grams per liter;

(h) inorganic alkali agents sufficient to provide a pH of at least 11; and

(i) water sufficient to make up 1 liter.

[0015] The developing agents for silver halide photographic elements suitable for the purposes of the present invention include hydroquinone and substituted hydroquinones (e.g. t-butylhydroquinone, methylhydroquinone, dimethylhydroquinone, chlorohydroquinone, dichlorohydroquinone, bromohydroquinone, 1,4-dihydroxynaphthalene, methoxyhydroquinone, ethoxyhydroquinone, etc.). Hydroquinone, however, is preferred. Said silver halide developing agents are generally used in an amount from about 5 to 50, preferably 10 to 30 grams per liter of the developing solution.

[0016] Such developing agents can be used alone or in combination with auxiliary developing agents which show a superadditive developing effect, such as p-aminophenol and substituted p-aminophenols (e.g. N-methyl-p-aminophenol or metol and 2,4-diaminophenol) and pyrazolidones (e.g. 1-phenyl-3-pyrazolidone or phenidone) and substituted pyrazolidones (e.g. 4-methyl-l-phenyl-3-pyrazolidone and 4,4'-dimethyl-1-phenyl--3-pyrazolidone). Phenidone, however, is preferred. These auxiliary developing agents are generally used in an amount from about 0.1 to 15, preferably 0.2 to 5 grams per liter of the developer.

[0017] The alkali metal sulfites, useful in the developer formulation of this invention as preservatives, include for example sodium and potassium metabisulfite. These are used in an amount from about 15 to 100, preferably 20 to 50 grams per liter of the developer solution.

[0018] The organic antifoggant agents, known in the art to eliminate fog on the developed photographic silver halide films, useful in the developer formulations of this invention include derivatives of benzimidazole, benzotriazole, tetrazole, indazole, thiazole, etc. It has been found, however, that particular mixtures of these antifoggant agents are particularly useful in the developer formulations of this invention to assure low fog levels in any working condition and in case of fast silver halide emulsion films having a greater tendency to fog. Such preferred mixtures include mixtures of 5-nitroindazole and benzimidazole nitrate, 5-nitrobenzotriazole and I-phenyl-5-mercaptotetrazole and benzotriazole and 1-phenyl-5-mercaptotetrazole. The most preferred combination is benzotriazole and 1-phenyl-5-mercaptotriazole, especially when the developer composition ready for use undergoes a storage prolonged in time, for instance more than 15 days at room temperature, before being used. These mixtures are used in a total .amount of from about 0.1 to 3, preferably 0.2 to 1.5 grams per liter of the developer composition. Of course optimum quantities of each compound and proportions can be found by the skilled in the art to respond to specific technical needs. It has been observed, for example, that an excess of l-phenyl-5-tcercaptotetrazole may cause or induce some solarization process especially while developing a color reversal film in a conventional first black-and-white development within a color reversal process. Analogously, an excess of benzotriazole has been found to be related to a decrease of maximum density.

[0019] It has been observed, as well, that 5-nitroindazole and benzimidazole give particularly good results when used together in mixtures which contain from 20 to 80 percent (in weight) of one of them with respect to the total mixture. Additionally, benzotriazole and 5-nitrobenzotriazole have been found to give the best results when used in mixture with 1-phenyl-5-mercaptotetrazole, the latter being present in minor amount with respect to the total mixture, for example in a percent of less than 20 percent, preferably less than 10 percent.

[0020] Inorganic alkali agents are used in the developer formulations of this invention to achieve the preferred pH range which is above 10. Such inorganic alkali agents include KOH, NaOH, potassium and sodium carbonate, etc.

[0021] Other adjuvants well known in the art can be used in the developer formulation of the present invention; these include restrainers, such as soluble halides (e.g. KBr and NaBr), solvents, buffers (e.g. borates and carbonates), development accelerators, and the like.

[0022] In order to be stable to aerial oxidation even during working at high temperatures in continuous transport processing machines, the developer compositions according to the present invention are characterized by the combination of an alkanolamine with the selected sequestering agents above. Alkanolamines suitable for the purpose of the present invention include the hydroxyalkylamines having the general formula:

wherein R and R each are a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms or a benzyl group, R ₃ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms and n is an integer of from 1 to 10.

[0023] Preferred alkanolamines include 2-benzylaminoethanol, ethanolamine, diethanolamine, triethanolamine, choline chloride, 3-amino-1-propanol, 1-amino-2-propanol, 2-amino-2-methyl-1,3-propanediol, tris-(hydroxymethyl)-aminopropane, 2-methylamino-ethanol, 2-dimethyl- amino-ethanol, 2-ethylamino-ethanol, bis-(2-hydroxypropyl)-amine, 3-dimethylamino-1-propanol and 2-isopropylaminomethanol. Most preferred alkanolamines include the ethanolamines such as diethanolamine, triethanolamine, methylaminoethanol, ethylaminoethanol, isopropylamino- ethanol and benzylaminoethanol. The alkanolamines are used in an amount from about 10 to 30, preferably 15 to 20 grams per liter of the developer composition.

[0024] The sequestering agents which combined with alkanolamines render the developer composition more stable to aerial oxidation are selected from the group of diethylenetetraminepentacetic acid (DTPA), 1,3-diamino-2-propanoltetracetic acid (DPTA) and l-hydroxyethyliden-1,1'-diphosphonic acid (HEDP). A still more stable combination in addition includes a compound selected from the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid. The sequestering agents of the former group are used in an amount from about 5 to 50, preferably 10 to 30 grams per liter of the developer solution and the compounds of the latter are used in an amount from about 5 to 100, preferably 15 to 50 grams per liter of the developer solution. Sequestering agents such as ethylenediaminotetracetic acid (EDTA), nitrilotriacetic acid (NTA) and nitrilotrimethylenephosphonic acid (NTPA), having chemical structures similar to those of some compounds of the former group, and compounds such as aminoacetic acid, oxalic acid, glycolic acid, malic acid, aspartic acid, glutammic acid and tartaric acid, having chemical structures similar to those of some compounds of the latter group, used in combination with alkanolamines, did not prove to be as effective as the selected ones in order to prevent developer degradation.

[0025] A particular preferred developer formulation will comprise the following ingredients:

[0026] Exposed black-and-white silver halide photographic films (e.g. Rapid Access films, X-ray films, Printing Papers, Reversal films) can be satisfactorily processed in machines containing the above reported developer solutions to yield high consistency in terms of sensitometric properties (speed, contrast, fog and maximum density) even if the developer solution is left in the machine processor for several days.

[0027] The developer formulation of the present invention may also be prepared from concentrated parts to be diluted with water and form the working solution just prior to its use. Such concentrated parts must be stable in the various storage conditions; problems may arise in making a single concentrated part of the developer solution as such for stability and it is normal practice in the art to divide and package it in two concentrated parts. These parts are combined and diluted with water to the desired strength and placed in the developing tank of the machine.

[0028] We have found that the developer formulations of the present invention may be advantageously prepared in a single concentrated part comprising a mixture of benzotriazole and 1-phenyl-5-mercaptotetrazole as antifoggant agent. When such single concentrated part is diluted with water to a working strength, a developer solution is obtained which assures low fog levels in any working conditions. The greater tendency of fast emulsion films to fog when processed at high temperature in continuous transport processing machines has been more effectively countered by said mixture of organic antifoggant agents. Of course, when the developer solution is made by two concentrated parts (a first part comprising the developing agents, the alkali metal sulfite, the alkanolamine and the sequestering agents and a second part comprising the organic antifoggant agents) the choice of such organic antifoggant agents appears not so critical and any mixture of antifoggant agents above described may be used.

[0029] A particular preferred concentrated formulation made in a single part according to the present invention will comprise the following ingredients:

[0030] The following examples, which further illustrate the present invention, report some experimental data in order to show the stability to aerial oxidation of the developer formulation of the present invention. In particular, the wavelength (in nm) at which the absorption of 100 ml of developer solution stored 3 days in a 1,000 ml conical flask in contact with air became 100% and the variation of pH between fresh and stored developer solution were measured. It is in fact well known that aerial oxidation of alkaline developers containing hydroquinone results in the liberation of alkali (and hence the pH will tend to rise) and in the darkening of the solution. In order to render more critical the aerial oxidation, in some experiments the developer solutions were added with small amounts of iron salts in addition to metal traces that may be present in water or in the chemicals used to compound the solutions. Examples of the present invention indicated with

have been prepared and/or evaluated together with examples of comparative nature indicated with _"^1.

Example 1

[0031] Eleven developer solutions for silver halide photographic materials (I to XI) were prepared according to the following table 1:

[0032] The ΔpH (measured at 20°C) and the wavelength values at which the stored solutions have an absorption of 100% (indicated as W₁₀₀) are reported hereinbelow in Table 2 (a longer W₁₀₀ corresponds to a higher degree of oxidation).

[0033] The developer solutions containing diethanolamine alone or in combination with EDTA and NTA and the solutions containing DTPA, DPTA, EDTA, NTA and HEDP alone, at the end of the experiment, resulted to be strongly colored and all showed a pH increase higher than 0.5. The solutions containing diethanolamine in combination with DTPA, DPTA and HEDP, on the contrary, resulted to be substantially colorless and showed a pH increase lower than 0.5.

Example 2

[0034] Three photographic developer solutions (XII to XIV) were prepared according to the following table 3:

[0035] The developer solution containing DTPA alone, at the end of the experiment, resulted to be strongly colored and showed a pH increase higher than 0.5. The solutions containing DTPA in combination with diethanolamine or triethanolamine, on the contrary, resulted to be substantially colorless and showed a pH increase lower than 0.5.

Example 3

[0036] Two X-ray developer replenishers (Dev. XV and XVI) suitable for processing X-ray film sheets in automatic processors were prepared according to the following Table 5:

[0037] 100 ml of each developer were stored for 3 days in a 1,000 ml conical flask in contact with air. ΔpH and W₁₀₀ were then measured. The values are reported hereinbelow in Table 6

Example 4

[0038] Three developers for rapid access processing machines were prepared according to the following Table 7:

[0039] 100 ml of each developer were stored in a 1,000 ml conical flask in contact with air. pH at 20°C and W were then measured at various storage times. Their values are reported hereinbelow in Table 8.

Example 5

[0040] 1,000 ml of developers XVII and XVIII were each stored in a 1,500 ml porcelain capsule at room temperature for 3 days.

[0041] Samples of various commercially available graphic art films were exposed and processed according to the following processing line:

using both fresh and stored developers.

[0042] The sensitometric characteristics of the processed films are reported in the following Table 9. (follows Table 9)

Example 6

[0043] A liquid concentrated developer (Concentrated Developer XIX), consisting of two parts, was prepared as follows:

Part A:

[0044] 

having a pH at 20°C = 10.90.

Part B:

[0045] 

A second liquid concentrated developer (Concentrated Developer XX) was prepared in a single part having the components of Parts A and B of Conc. Developer XIX, according to the following composition:



having a pH at 20°C = 10.90.

[0046] A third liquid concentrated developer (Concentrated Developer XXI), consisting of two parts, was prepared as follows:

Part A:

[0047] 

having a pH at 20°C = 10.95.

Part B:

[0048] 

having a pH at 20°C = 10.50.

[0049] A fourth liquid concentrated developer (Concentrated Developer XXII) was prepared in a single part having the components of Parts A and B of Conc. Developer XXI, according to the following composition:

[0050] pH at 20°C = 10.97.

[0051] A fifth liquid concentrated developer (Concentrated Developer XXIII) was prepared as follows:

having a pH at 20°C = 10.94.

[0052] Ten ready-for-use developers were prepared from the above concentrated developers according to the following Table 10:

(follows Table 10)

[0053] Sheets of unexposed 3M LOC4 Contact Film were developed in the above described ready-for-use developers for 60" at 35°C, treated in a stop bath comprising 4% acetic acid for 15" at 35°C, fixed in 3M Fix Roll M for 30" at 35°C and finally washed for 5' at 35°C.

[0054] The following table (Table 11) reports the minimum density (fog) values of the developed sheets.

Example 7

[0055] Six black-and-white developers were prepared according to the following formula. The sequestering power versus Fe⁺⁺ (tested with (NH₄)₂Fe(SO₄)₂) were measured: the values thereof are reported hereinbelow in Table 12.

[0056] (follows Table 12)

[0057] 

Example 8

[0058] Seven developer compositions for rapid access processing machines were prepared according to the following Table 13:

(follows Table 13)

[0059] 100 ml of each developer were stored at room conditions in a 1,000 ml conical flask in contact with air. ΔpH after 24 hour storage; absorption λmax after 72 hour storage; time to reach W₁₀₀ = 600; and fog of an unexposed 3M LOC4 Film, developed for 60" at 35°C in the above fresh developers (fixed as described in Example 8), were measured. The values are reported in the following Table 14.

[0060] The above times to have W₁₀₀=600 are well sufficient to maintain the stability of the developer solution left in the processing machine without working during interruptions (e.g. during week-ends). Of course, in the normal working conditions a much longer stability of the developer solution (e.g. one or two months) is secured by the replenishment operation; said stability results in any case higher in the presence of the combination of the alkanolamines and the selected sequestering agents according to the present invention.

Claims

1. A developer composition for silver halide photographic materials comprising hydroquinone or a substituted hydroquinone, an alkali metal sulfite, an organic antifogging agent and inorganic alkali agents, characterized in that said developer composition comprises an alkanolamine and a sequestering agent selected in the group of diethylenetetramine pentacetic acid, 1,3-diamino-2-propanoltetracetic acid and 1-hydroxyethylidene-1,1'-diphosphonic acid.

2. The developer composition for silver halide photographic materials according to claim 1 further comprising a compound selected in the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid.

3. The developer composition for silver halide photographic materials according to claim 1 further comprising an auxiliary developing agent selected in the class of substituted pyrazolidone and p-aminophenol compounds.

4. The developer composition for silver halide photographic materials according to claim 1, in which the organic antifoggant agent is selected in the group of mixtures of 5-nitroindazole and benzimidazole nitrate, 5-nitrobenzotriazole and l-phenyl-5-mercaptotetrazole, and benzotriazole and I-phenyl-5-mercaptotetrazole.

5. The developer composition for silver halide photographic materials according to claim 1, in which the alkanolamine is selected in the group of diethanolamine, triethanolamine, 2-benzylaminoethanol, 2-methylaminoethanol, 2-ethylaminoethanol and 2-isopropylamino- ethanol.

6. A developer composition for silver halide photographic materials comprising:

(a) hydroquinone or a substituted hydroquinone in an amount of 10 to 30 grams per liter;

(b) an auxiliary developing agent in an amount of 0.2 to 5 grams per liter;

(c) an alkali metal sulfite in an amount of 20 to 50 grams per liter;

(d) an alkanolamine in an amount of 5 to 20 grams per liter;

(e) an organic antifoggant agent selected in the group of mixtures of 5-nitroindazole and benzimidazole nitrate, 5-nitrobenzotriazole and 1-phenyl-5-mercaptotetrazole and benzotriazole and 1-phenyl-5-mercaptotetrazole in an amount of 0.2 to 1.5 grams per liter;

(f) a sequestering agent selected in the group of diethylenetetraminopentacetic acid, 1,3-diamino-2-propanoltetracetic acid and 1-hydroxyethylidene-1,1^1-diphosphonic acid in an amount of 10 to 30 grams per liter;

(g) a compound selected in the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid in an amount of 15 to 50 grams per liter;

(h) inorganic alkali agents sufficient to provide a pH of at least 10; and

(i) water sufficient to make up 1 liter.

7. A concentrated developer composition for silver halide photographic materials, to be diluted with water to form a ready-for-use developer composition, comprising hydroquinone or a substituted hydroquinone, an alkali metal sulfite and inorganic alkali agents, characterized in that it contains an alkanolamine, a sequestering agent selected in the group of diethylenetetraminopentacetic acid, 1,3-diamino-2-pro- panoltetracetic acid and 1-hydroxyethyliden-1,1'-diphosphonic acid, and a mixture of benzotriazole and I-phenyl-5-mercaptotetrazole antifogging agents.

8. The concentrated developer composition for silver halide photographic materials according to claim 7 which comprises a compound selected in the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid.

9. The concentrated developer composition for silver halide photographic materials according to claim 7 which comprises diethanolamine as alkanolamine.

10. The concentrated developer composition for silver halide photographic materials according to claim 7 which comprises an auxiliary developing agent selected in the class of substituted pyrazolidone and p-aminophenol compounds.

11. A concentrated developer composition for silver halide photographic materials, to be diluted with water to form a ready-for-use developer composition, comprising:

(a) hydroquinone or a substituted hydroquinone in an amount of 40 to 120 grams per liter;

(b) a auxiliary developing agent in an amount of 0.5 to 20 grams per liter;

(c) an alkali metal sulfite in an amount of 80 to 200 grams per liter;

(d) an alkanolamine in an amount of 20 to 120 grams per liter;

(e) a mixture of benzotriazole and 1-phenyl-5-mercaptotetrazole antifogging agents in an amount of 0.8 to 6 grams per liter;

(f) a sequestering agent selected in the group of diethylenetetraminepentacetic acid, 1,3-diamino-2-propanoltetracetic acid and 1-hydroxyethylidene-1,1^1-diphosphonic acid in an amount of 20 to 150 grams per liter;

(g) a compound selected in the group of polyphosphates, phosphoric acid, acetic acid, lactic acid and citric acid in an amount of 50 to 150 grams per liter;

(h) inorganic alkali agents sufficient to provide a p_h of at least 11; and

(i) water sufficient to make up 1 liter.