Alkaline black-and-white photographic developer

Abstract

 Alkaline aqueous black-and-white photographic developer for processing of silver halide radiographic materials comprising (1) a hydroquinone, (2) a 3-pyrazolidone developing agent, (3) a dialdehyde hardener, (4) antifoggants, (5) a sequestering agent, (6) a sulfite antioxidant, and (7) a buffering agent wherein said sequestering agent is a cyclicaminomethane diphosphonic acid compound. Preferably, the antifoggants comprise a combination of a benzotriazole-type antifoggant, an indazole-type antifoggant and a mercaptotetrazole-type antifoggant.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to an alkaline black-and-white developer for processing a silver halide photographic material and, more particularly, to an alkaline black-and-white hardening developer for processing a silver halide radiographic material in an automatic processor. The developer provides improved stability and excellent photographic properties.

BACKGROUND OF THE INVENTION

[0002] Aqueous black-and white developers used for processing silver halide photographic materials comprise, as main components, hydroquinone and 3-pyrazolidone developing agents, an alkali agent, an organic antifoggant and a sulfite.

[0003] It is well known in the art that when silver halide photographic materials are to be processed rapidly in an automatic processor, a dialdehyde-type hardener is added to the developer in order to increase the mechanical strength of the photographic material during processing (see, for example, US Pat Nos. Re 26,601, 3,232,761 and 3,545,971, and GB Pat. No. 1,269,268). It is normal practice to subject silver halide radiographic materials to rapid processing in an automatic processor using a hardening developer.

[0004] A problem that is frequently encountered with said hardening developers is the tendency of the developing agent to degrade during storage and use. In order to increase the stability of the hardening developer it is normal practice in the photographic art to add a sulfite. The higher the amount of the sulfite, the longer the useful life of the developer. However, high concentrations of sulfites in a developer cause a reduced activity and dark deposits in the developer tank. Additionally, the presence of metal ion traces (such as Fe⁺⁺ in the developer causes the catalitic oxidation of the sulfites. Sequestering agents such as ethylenediaminetetraacetic acid (EDTA), used to prevent the precipitation of calcium salts in the developers, in the presence of traces of iron ions cause the autoxidation of the hydroquinone developing agent at a higher rate than in the absence of the EDTA.

[0005] US Pat. NO. 4,672.025 describes a black-and-white developer comprising hydroquinone, a 3-pyrazolidone developing agent, a dialdehyde hardener, an organic antifoggant and a sequestering agent selected from the group consisting of diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexa- acetic acid (TTHA), 1,3-diamino-2-propanoltetraacetic acid (DPTA), glycol ether diaminetetraacetic acid, ethylenediaminetetramethylenephosphonic acid (EDTP), aminotrimethylenephosphonic acid and alkali metal salts of said acids. The use of said chelating agents versus the previously used ethylenediaminetetraacetic acid (EDTA) increases the stability of the developer and prevent the formation of a precipitate in a developer comprising a dialdehyde hardener.

[0006] European Patent Application No. 286,874 describes the use of a dialkylaminomethane diphosphonic acid sequestering agent (including cyclicaminomethane diphosphonic acids) in aqueous alkaline photographic developers to increase the stability of the developers and inhibit deposit formation. Said developers does not include hardeners and are intended for manual processing, preferably of silver halide color photographic materials.

[0007] US Pat. No. 4,810,622 describes a black-and-white developer having a pH value of 9.2 to 10 comprising hydroquinone, a 3-pyrazolidone developing agent, a dialdehyde hardener, an organic antifoggant, a chelating agent selected form the group consisting of diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), 1,3-diamino-2-propanoltetraacetic acid (DPTA), ethylenediaminetetramethylenephosphonic acid (EDTP), aminotrimethylenephosphonic acid and alkali metal salts of said acids, a silver halide solvent and a sulfite. The developer is suitable for processing in an automatic processing machine of black-and-white negative silver halide photographic materials different from X-ray materials, such as negative films for cameras, printing papers and microfilms.

[0008] Accordingly, although many compounds have been proposed as sequestering agents for use in photographic developers, there is still the need to have compounds able to increase the stability of photographic hardening developers for the rapid processing of silver halide photographic materials, especially silver halide radiographic materials, in automatic processing machines, especially at high processing temperatures, and provide excellent photographic properties.

SUMMARY OF THE INVENTION

[0009] Alkaline aqueous black-and-white photographic developers for processing of silver halide radiographic materials comprise (1) a hydroquinone, (2) a 3-pyrazolidone developing agent, (3) a dialdehyde hardener, (4) antifoggants, (5) a sequestering agent, (6) a sulfite antioxidant, and (7) a buffering agent, wherein said sequestering agent is a cyclicaminomethane diphosphonic acid compound. Preferably, the antifoggants comprise a combination of a benzotriazole-type antifoggant, an indazole-type antifoggant and a mercaptotetrazole-type antifoggant.

[0010] The developer is stable over long periods of time and can provide excellent photographic properties when used in automatic processing machines. The developer allows control of the photographic characteristics (fog anf gradation) even when used at high temperature for rapid processing.

[0011] The present invention relates to an alkaline aqueous black-and-white photographic developer, for processing a silver halide photographic material, particularly a silver halide radiographic material, comprising (1) at least one of hydroquinones, (2) at least one of 3-pyrazolidone developing agents,(3) at least one of dialdehyde hardeners, (4) at least one antifoggant, (5) a sequestering agent, (6) a sulfite antioxidant, and (7) a buffering agent, characterized in that said sequestering agent is a cyclicaminomethane diphosphonic acid compound.

[0012] In a preferred aspect, the present invention relates to an alkaline developer as described above, wherein the antifoggant comprise a combination of a benzotriazole-type antifoggant, an indazole-type antifoggant and a mercaptotetrazole-type antifoggant.

[0013] The cyclicaminomethane diphosphonic acid compounds used in the developer of this invention are those described in the European Patent Application No. 286,874. Preferably, said cyclicaminomethane diphosphonic acid compounds correspond to the following formula


wherein R₁, R₂ and R₃, equal or different, each represent a hydrogen atom or a PO₃M'''group, wherein M'and M'' represent a hydrogen atom, an alkaline metal such as Li, Na or K or a quaternary ammonium group such as ammonium, pyridinium, triethanolammonium or triethylammonium, and Q represents the atoms or chemical bonds necessary to complete a 3- to 6-membered ring such as aziridino, pyrrolidino, imidazolidino, piperidino, isoindolino or morpholino, with the proviso that at least two of R₁, R₂ and R₃ substituents represent a PO₃M'''group.

[0014] Typical examples of sequestering agents within the general formula above are:

[0015] Said sequestering agents can be advantageously used in amounts of about 0.0005 to about 0.5 moles per liter, preferably of about 0.008 to about 0.1 moles per liter of the developer.

[0016] The above sequestering agents can be used in combination with other sequestering agents known in the art such as, for example, aminopolycarboxylic acids (ethylenediaminotetraacetic acid, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, diaminopropanoltetraacetic acid, etc.), aminopolyphosphonic acids (methylaminophosphonic acid, phosphonic acids described in Research Disclosure 18837 of December 1979, phosphonic acids described in US Pat. No. 4,596,764, etc.), polyphosphate compounds (sodium hexametaphosphate, etc.), α-hydroxycarboxylic acid compounds (lactic acid, tartaric acid, etc.), dicarboxylic acid compounds (malonic acid, etc.), α-ketocarboxylic acid compounds (pyruvic acid, etc.), alkanolamine compounds (diethanolamine, etc.), etc.

[0017] The sequestering agents incorporated into the black-and-white hardening developer of the present invention, have been found to increase the stability of the developer over a long period of time.

[0018] The developer composition of a present invention is suitable for obtaining black-and white images upon development of light-exposed silver halide photographic materials, in particular radiographic materials. Generally, it comprises a black-and-white developing agent, a dialdehyde hardener, a sulfite antioxidant, an antifoggant agent, buffering agents and alkaline agents.

[0019] Black-and-white developing agents for use in the present invention include hydroquinone and hydroquinone derivatives (for example t-butylhydroquinone, methylhydroquinone, dimethylhydroquinone, chlorohydroquinone, dichlorohydroquinone, bromohydroquinone, 1,4-dihydronaphthalene, methoxyhydroquinone, ethoxyhydroquinone, hydroquinone monosulfonate, hydroquinone disulfonate, etc.). Hydroquinone, however, is preferred. Said black-and-white developing agents are generally used in amounts of from 0.075 to 0.75 moles per liter, preferably of from 0.10 to 0.50 moles per liter of developer.

[0020] Said black-and-white developing agents are used in combination with auxiliary developing agents which show a superadditive developing effect, such as p-aminophenol and p-aminophenol derivatives (such as N-methyl-p-aminophenol and 2,4-diaminophenol) and pyrazolidone compounds (such as 1-phenyl-3-pyrazolidone) and pyrazolidone derivatives (such as 4-methyl-1-phenyl-3-pyrazolidone and 4,4'-dimethyl-1-phenyl-3-pyrazolidone).
1-Phenyl-3-pyrazolidone, however, is preferred. Said auxiliary developing agents are generally used in amounts of from 0.0003 to 0.15 moles per liter, preferably of form 0.003 to 0.1 moles per liter of developer.

[0021] Dialdehyde hardeners used in the developer of this invention include, for example, glutaraldehyde, α-methylglutaraldehyde, β-methylglutaraldehyde, maleic dialdehyde, succinic dialdehyde, methoxysuccininc dialdehyde, α-methoxy-β-ethoxyglutaraldehyde, α-n-butoxyglutaraldehyde, α,α-dimethoxysuccinic dialdehyde, β-isopropylsuccinic dialdehyde, α,α-diethylsuccinic dialdehyde, butylmaleic dialdehyde, and bisulfite adducts of these aldehydes. Of the above compounds, glutaraldehyde and its bisulfite adducts are most preferred. Said dialdehyde hardeners are generally used in amounts of from 0.001 to 0.3 moles per liter, preferably of from 0.01 to 0.1 moles per liter of developer.

[0022] Antioxidants are generally sulfites. With sulfites we mean here those compounds known in the art as capable of generating sulfite ions (SO₃-- in aqueous solutions and include sulfites, bisulfites, metabisulfites (1 mole of metabisulfite forming 2 moles of bisulfite in aqueous solution) and aldehyde bisulfite adducts. Examples of sulfites, bisulfites, metabisulfites include sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium sulfite, potassium bisulfite, potassium metabisulfite and ammonium metabisulfite. The amount of the total sulfite ions is preferably not less than 0.05 moles, more preferably 0.1 to 1.25 moles, and most preferably 0.3 to 0.9 moles, per liter of developer. The amount of the sulfite ions with respect to the hydroquinone preferably exceeds a molar ratio of 2:1 and, more preferably, is between 2.5:1 to 4:1.

[0023] Antifoggants, which are known in the art to control the fog appearence in processed photographic materials, useful in the developer of the present invention include benzimidazole-, benzotriazole-, mercaptoazole-, indazole- and mercaptothiadiazole-type antifoggants. Preferred antifoggants include 5-nitroindazole, benzimidazole nitrate, 5-methylbenzotriazole and 1-phenyl-5-mercaptotetrazole. Said compounds are used, alone or in combination, in amounts of from about 1x10⁻⁶ to about 5x10⁻¹ moles per liter, preferably of from about 5x10⁻⁴ to about 1x10⁻¹ moles per liter of the developer.

[0024] Preferably, according to the present invention, the developer comprises a combination of benzotriazole-, indazole- and mercaptoazole-type antifoggants, more preferably a combination of 5-methylbenzotriazole, 5-nitroindazole and 1-phenyl-5-mercaptotetrazole. Preferably, said combination comprises from 7x10⁻⁵ to 0.04 moles per liter of said benzotriazole-type antifoggant, from 6x10⁻⁶ to 0.03 moles per liter of said indazole-type antifoggant and from 6x10⁻⁶ to 0.02 moles per liter of said mercaptoazole type antifoggant. Examples of mercaptoazoles are described in US Pat. No. 3,576,633, and examples of indazole-type antifoggants are described in US Pat. No. 2,271,229. The developer, comprising said antifoggant combination, is advantageously used in a continous transport processing machine at high temperature processing (higher than 35°C) for processing of X- ray materials without changes in the sensitometric properties of the material, mainly without a substantial increase of the fog of the developed material.

[0025] Accordingly, in a preferred aspect the present invention relates to an alkaline aqueous black-and-white photographic developer, for processing a silver halide photographic material, particularly a silver halide radiographic material, comprising (1) at least one hydroquinone, (2) at least one 3-pyrazolidone developing agent, (3) at least one dialdehyde hardener, (4) at least one antifoggant, (5) a sequestering agent, (6) a sulfite antioxidant, and (7) a buffering agent, characterized in that said sequestering agent is a cyclicaminomethane diphosphonic acid compound and the antifoggant comprises a combination of a benzotriazole-type antifoggant, an indazole-type antifoggant and a mercaptotetrazole-type antifoggant.

[0026] The developer in accordance with the present invention further includes a buffer (e.g., carbonic acid salts, phosphoric acid salts, polyphosphates, metaborates, boric acid and boric acid salts). The amount of the buffer with respect to the sulfite preferably exceeds a molar ratio of 0.5:1 and, more preferably, is between 1:1 to 2:1.

[0027] In the developer composition there are used inorganic alkaline agents to obtain the preferred pH which is usually higher than 10. Said inorganic alkaline agents include KOH, NaOH, LiOH, sodium and potassium carbonate, etc.

[0028] Other adjuvants well known to the skilled in the art of developer formulation may be added to the developer of the present invention. These include restrainers, such as the soluble halides (e.g., KBr), solvents (e.g., polyethylene glycols and esters thereof), development accelerators (e.g., polyethylene glycols and pyrimidinium compounds), preservatives, surface active agents, and the like.

[0029] The developer of the invention is prepared by dissolving the ingredients in water and adjusting the pH to the desired value. The developer may also be prepared in a concentrated form and then diluted to a working strength just prior to use. The developer may be prepared in two or more concentrated parts to be combined and diluted with water to the desired strength and placed in the developing tank of the automatic processing machine.

[0030] The developer of the present invention is particularly useful when processing is carried out in an automatic processing machines. Automatic processing machines may be of the type described in US Pat. No. 3,545,971, such as an "X-OMAT Processor" made by Eastman Kodak Company, of the series of "TRIMATIC" Processors made by 3M Company and of the type of "Model RK" made by Fuji Photo Film Company. The developing temperature and the developing time are in relation to each other and are dependant on the total processing time. In general, they are about 20°C to 50°C, and 10 seconds to 1.5 minutes, respectively.

[0031] After development in the developer of the present invention, the silver halide material is fixed, preferably in an acid fixer, and washed and dried in the usual manner. In the automatic processing machine, these steps are determined by the machine.

[0032] The silver halide photographic materials which can be used in the present invention comprise a support and at least one silver halide emulsion layer coated on the support. The silver halide emulsion layermay be coated on one side of the support or on both sides thereof. The silver halide photographic element can comprise other non light-sensitive layers, such as backing layers, antihalation layers, interlayers, filter layers, protective layers. The silver halide emulsion comprise silver halide grains (such as silver chloride, silver bromide, silver chlorobromide, silver bromoiodide, silver chlorobromoiodide) dispersed in an hydrophilic colloid (such as gelatin, modified gelatins, albumin, casein, sodium alginate, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone and mixtures thereof). The emulsion can contain cubic, octahedral, spherical and/or tabular silver halide grains. The emulsion can be chemical and optical sensitized and added during its manufacture or before its coating various additives, such as stabilizers, antifoggants, hardeners, coating aids, etc. The silver halide emulsion is coated on a support such as a cellulose acetate film, or a polyethylene terephthalate film using coating methods well known in the art, and dried.

[0033] The silver halide photographic materials to be used in the present invention are preferably black-and-white radiographic materials of high gradation (contrast) and particularly preferably materials which provide a gradation of 1.5 to 4.0.

[0034] The following Examples illustrate the aqueous alkaline black-and-white developer of this invention more specifically, being understood, however, that the invention is not limited to these examples.

EXAMPLE 1

[0035] Developers 1 to 4 having the composition shown in Table 1 for radiographic silver halide photographic materials were prepared.

[0036] Twenty five milliliters of each of the developers was placed in an open plastic bottle of fifty milliliters and left to stand at 40°C for seven days. Then the ability to chelate Fe⁺⁺ ions was examined and the time for changing the color of the developer from colorless (or pale yellow) to dark brown, corresponding to the useful time of the developer, measured. The results are summarized in Table 2 wherein time (in hours) of useful time and sequestering power (in parts per million) versus Fe⁺⁺ ions are reported.

EXAMPLE 2

[0037] Concentrated parts of developers, to be combined and diluted to the desired strength with water, having the composition shown in Table 3 were prepared.

[0038] Two developers (5 and 6) were prepared combining the concentrated parts following Table 4.

[0039] Two liters of each of the developers 5 and 6 were placed in an open evaporating dish and left to stand at room temperature for ten days (oxidized developer). Then, pH, color at 400 nm and the main components of the developers were determined. The results are summarized in the following Table 5.

[0040] A double layer coated radiographic film 3M type XD-A and a single layer coated radiographic film 3M type MS-3 were processed using developers 5 and 6, fresh and oxidized, for 20 seconds at 35°C, followed by fixing in 3M XAF/3 Fixer for 24 seconds at 30°C, washing in tap water for 22 seconds at 35°C and drying for 22 seconds at 35°C. The results are summarized in the following Table 6.

EXAMPLE 3

[0041] Developers 7 to 11 having the composition shown in Table 7 for radiographic silver halide photographic materials were prepared.

[0042] A hundred milliliters of each of the developers was placed in an open flask of one liter and left to stand at room temperature for one to six days. The pH of each developer and the Dmax of samples of 3M type XD-A radiographic films developed for 60 seconds at room temperature in each developer were measured during the time. The following Table 8 reports the values of pH and and Dmax.

EXAMPLE 4

[0043] Developers 12 to 15 having the composition shown in Table 9 for radiographic silver halide materials were prepared.

[0044] A green sensitive double layer coated radiographic film 3M type XD-A and a blue sensitive double layer coated radiographic film 3M type R-2 were processed using the developers above for 20 seconds at 39°C, followed by fixing in 3M XAF/3 Fixer for 24 seconds at 30°C, washing in tap water for 22 seconds at 35°C and drying for 22 seconds at 35°C. The results are summarized in the following Table 10.

Claims

1. An alkaline aqueous black-and-white photographic developer comprising

(1) a hydroquinone,

(2) a 3-pyrazolidone developing agent,

(3) a dialdehyde hardener,

(4) at least one antifoggant,

(5) a sequestering agent,

(6) a sulfite antioxidant, and

(7) a buffering agent,

wherein said sequestering agent is a cyclicaminomethane diphosphonic acid compound.

2. The alkaline aqueous developer of claim 1, wherein said cyclicaminomethane diphosphonic acid compound corresponds to the following formula

wherein R₁, R₂ and R₃, equal or different, each represent a hydrogen atom or a PO₃M'''group, wherein M'and M'' represent a hydrogen atom, an alkaline metal or a quaternary ammonium group, and Q represents the atoms or chemical bonds necessary to complete a 3- to 6-membered ring, with the proviso that at least two of R₁, R₂ and R₃ substituents represent a PO₃M'''group.

3. The alkaline aqueous developer of claim 1, wherein the sequestering agent corresponds to the formula

4. The alkaline aqueous developer of claim 1, wherein the sequestering agent is used in an amount of from 5x10⁻⁴ to 5x10⁻¹ moles per liter of developer.

5. The alkaline aqueous developer of claim 4, wherein the hydroquinone is present in the developer in an amount of from 0.075 to 0.75 moles per liter, the 3-pyrazolidone developing agent is present in an amount of from 3x10⁻⁴ to 0.15 moles per liter, the dialdehyde hardener is present in an amount of from 1x10⁻³ to 0.3 moles per liter, the antifoggants are present in an amount of from 1x10⁻⁶ to 0.1 moles per liter, the molar ratio of the sulfite antioxidant to hydroquinone is at least 1.5:1 and the molar ratio of the buffering agent to the sulfite antioxidant is at least 0.5:1.

6. The alkaline aqueous developer of claims 1 to 5, wherein the antifoggants comprise a combination of a benzotriazole-type antifoggant, an indazole-type antifoggant and a mercaptotetrazole-type antifoggant.

7. The alkaline aqueous developer of claim 6, wherein said antifoggant combination comprises from 7x10⁻⁵ to 0.04 moles per liter of said benzotriazole-type antifoggant, from 6x10⁻⁶ to 0.03 moles per liter of said indole-type antifoggant and from 6x10⁻⁶ to 0.02 moles per liter of said mercaptotetrazole-type antifoggant.