Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/305—Additives other than developers
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/30—Developers
  • G03C2005/3007—Ascorbic acid
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C2200/00—Details
  • G03C2200/34—Hydroquinone
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C2200/00—Details
  • G03C2200/40—Mercapto compound
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/30—Developers
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/30—Developers
  • G03C5/3028—Heterocyclic compounds
  • G03C5/3035—Heterocyclic compounds containing a diazole ring
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
  • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
  • G03C5/29—Development processes or agents therefor
  • G03C5/305—Additives other than developers
  • G03C5/3053—Tensio-active agents or sequestering agents, e.g. water-softening or wetting agents

Definitions

• the present invention relates to a developer composition having less tendency to sludge formation in the developing step of the processing of light-sensitive silver halide photographic materials.
• a solution for the problem of sludge formation as has been set forth has e.g. been given in EP-A's 0 136 582, 0 223 883, 0 785 467 and 0 789 272 and in US-A 5,240,823, wherein thioctic acid, polysulfide compounds having carboxylic acid, sulfonic acid, etc. and aminoalkane thiosulfonic acid or a salt thereof have been used.
• Another measure applied in order to reach the same effects can be obtained by making use of a compound inhibiting dissolution by adsorption at the surface of the silver halide crystals. Protection of the said surface by adsorption effectively inhibits the dissolution of silver halide indeed, so that less silver ions are diffusing into the developer solution.
• a disadvantage however is the simultaneous inhibition of the velocity of the developing reaction so that a strong influence on sensitometry may occur in that speed, maximum density and contrast may be suppressed.
• Useful agents inhibiting dissolution of silver halide in a developer composition have been proposed as e.g. thioether compounds in US-A 5,821,040; the mercapto-s-triazines from US-A 5,300,410 and the mercapto or disulfide compounds in US-A 5,364,746.
• a suitable measure is to provide the presence of complexing agents into the said developer in order to occlude silver ions into a complex, forming a complex ion wherein the silver ions are protected against reduction by reducing developing agents.
• the said complex ion opposite to silver metal formed by reduction, remains in the developer solution without causing sludge formation.
• Another object of the present invention is to reduce the frequency of cleaning tanks containing developer solution in an automatic processor to at most twice a year.
• a black-and-white silver halide developer composition comprising, besides one or more developing agent(s), agent(s) preventing oxidation thereof and agent(s) providing pH buffering, at least one silver complexing agent, characterized in that said silver complexing agent has a silver complexing stability ratio of at least 70 %, wherein said silver complexing stability is determined after dissolving 50 mg of the said complexing agent in 200 ml of said developer composition, adding thereto under constant vigorous stirring 74 ml of a solution of silver nitrate having a concentration of 0.0005 moles/liter, adding over a period of 30 minutes said solution to the said developer solution thereby providing a total amount of added silver expressed as equivalent amount of silver nitrate of 15 mg/l, leaving said solution unstirred in order to provide an equilibrium state between formed precipitate and supernatant developer liquid and measuring the silver content in the said supernatant liquid after 3 weeks; wherein said complex stability ratio is calculated as ratio of silver content in superna
• the developer solution one of the solutions required in a processing cycle of black-and-white silver halide photographic materials may be any of the solutions which is used in order to develop said black-and-white photographic material, i.a. a starting solution, a seasoned developer, a developing solution ready-for-use or the concentrated developer compositions thereof.
• the developer solution chemistry in the processor is the replenishment developer solution chemistry, whether or not with a supplementary additive mixed therewith, said supplementary additive being the developer starter solution.
• Said “fresh developer” is defined as the developer present in the developer unit of the processor before any film has passed, or in the alternative, the developer in which a very little amount of film was run, well before a steady state or equilibrium situation is reached (e.g. resulting in a "half-seasoned” developer in “running equilibrium conditions”).
• developer replenisher solution is defined as the unused developer present in the developer container which is, in the method of the present invention, mixed in the developer unit with developer starter solution in order to prepare the "fresh developer” solution defined hereinbefore. It is clear that said “developer replenishing solution” is added further to the developer unit as the film is being processed, acting as a commonly used “replenisher” too.
• the "seasoned developer” is defined as the developer present in the developer unit of the processor after processing enough film in order to reach a steady-state or an equilibrium situation, depending on the amounts of replenisher used. In order to reach said steady-state, the said developer is topped up with the "developer replenisher solution” defined hereinbefore.
• the said developer solution comprises a mixture of a developer starter solution and developer replenisher solution, wherein it is understood that both solutions have been mixed before addition to the developer unit or tank of the automatic processor.
• an additional step is the step of adding of a developer starter solution to the developer replenisher solution which is present in the said developer unit or tank.
• said developer starter solution is preferably added before starting processing, although it is not excluded to add the said developer starter solution during processing, i.e. after the processing has been started, before a "running equilibrium" or "seasoned” condition or state has been reached.
• addition of the said starter developer solution proceeds before starting the processing cycle, i.e.
• developer starter solution when adding developer starter solution to developer replenisher solution the latter being present in a developer unit or tank of the processor.
• developer starter solution is present in the developer tank before developer replenishing solution is added thereto and mixed therewith is however not excluded, so that more generally during processing the step of mixing of developer starter solution and fixer replenishing solution in a developer unit or tank of the said processor is possible.
• said developer starter solution is mixed with the developer replenishing solution in the processor before starting processing.
• the developer starter solution is a buffering solution.
• Said buffering solution alters pH of the developer to the required value: so in a preferred embodiment said developer starter solution alters pH to a value in the range from - 0.3 up to + 0.3 units of the pH of the developer solution after seasoning.
• said developer starter solution is water or an alkaline solution.
• an amount of developer starter solution is proportional to tank volume of the developer solution in the processor.
• an amount of developer starter solution is less than 10 % of volume of replenisher solution with which it is mixed upon starting processing.
• Developer solutions may contain glutardialdehyde as hardening agent but in a preferred embodiment the developer is free thereof. It is clear that the light-sensitive black-and-white silver halide photographic materials processed in the developer composition according to the present invention should be hardened to such an extent that in a developing step free from hardening agents no problems occur as e.g. "sludge formation" in form of troubles due to lack of physical strength properties of the materials.
• a survey of hardening agents available in order to foreharden coated hydrophilic gelatinous layers of the said photographic materials has been given e.g. in Research Disclosure 38957, Chapter II.
• a black-and-white silver halide developer composition comprising, besides one or more developing agent(s), agent(s) preventing oxidation thereof and agent(s) providing pH buffering, at least one silver complexing agent , characterized in that said silver complexing agent has a silver complexing stability ratio of at least 70 %.
• a silver complexing agent can be defined as an agent which has the ability to form water-soluble silver complexes, so that the silver complex thus formed is stable enough to withstand the reduction of the silver complex to metallic silver in the photographic developer.
• the silver complexing ability of said silver complexing agent is measured by a method containing following steps:
• said silver complexing stability is thus determined after dissolving 50 mg of the said complexing agent in 200 ml of said developer composition, adding thereto under constant vigorous stirring 74 ml of a solution of silver nitrate having a concentration of 0.0005 moles/liter, adding over a period of 30 minutes said solution to the said developer solution thereby providing a total amount of added silver expressed as an equivalent amount of silver nitrate of 15 mg/l, leaving said solution unstirred in order to provide an equilibrium state between formed precipitate and supernatant developer liquid and measuring the silver content in the said supernatant liquid after 3 weeks; wherein said complex stability ratio is calculated as ratio of silver content in supernatant liquid to total amount of silver added.
• a silver complexing agent as defined in the statement of the invention moreover makes, in a preferred embodiment, silver content of the developer in running equilibrium conditions increase in an amount of more than 1 mg per liter per mmole of said complexing agent.
• a substance which, in the conditions given above, has a complex stability ratio of more than 80% (thus belonging to the categories C1 or C2) as described in the experiment above is defined as a silver complexing substance suitable for use in the developer composition of the present invention.
• the design of the experiment is critical. In order to get a suitable and predictable value of actual properties, it is important to add the silver nitrate slowly and as a highly diluted solution, in order to prevent immediate sludging during the addition of the silver solution.
• the experiment proposed gives results which are relevant for the actual behaviour of the substances under investigation.
• said silver complexing agent is corresponding to the general formula (I) MS-L-X wherein
• MS- is linked to an aliphatic carbon atom.
• MS- is linked to an aliphatic carbon atom and X is a sulphonic acid or a sulphonate salt.
• the agent preventing silver dissolution or the silver elution inhibiting agent makes that upon processing of silver halide materials part of the silver halide crystals which is attacked by the photographic developer is not dissolved and eluted as such.
• the amount of silver dissolved if no use is made from such agent preventing silver dissolution is highly dependent on the exposure of the material to be developed. Non-exposed materials clearly release substantially more silver into the photographic developer solution, and thus give raise to relatively more sludge. In exposed materials however there is a competition between development and dissolution of the silver halide crystals and as a result there will be less sludge. The total amount of sludge is thus highly dependent on the development conditions, on the composition of the film material and on the developer solution.
• the silver content in the samples is determined immediately afterwards by AAS (atomic absorption spectrophotometry).
• AAS atomic absorption spectrophotometry
• the silver content after having transported 3 m and 6 m of film in the processing respectively is a measure for the "silver elution inhibition strength" of the inhibitor substance investigated for the particular combination of film and developer solution.
• the inhibition strength is then defined by comparing the silver content with and without the substance under investigation in the developer solution.
• the " inhibition strength ratio " of a given "inhibitor” or “silver elution inhibiting compound” is defined as the ratio of the silver content in the developer solution containing the sludge inhibiting substance and the silver content in the developer solution without the said substance after processing 3 m of film in the above defined conditions. According to the inhibition strength ratio, the inhibitors are classified as represented in Table 2 hereinafter. Inhibition Strength Ratio ( 3 m ) Appreciation Category I1 ⁇ 30% Very strong inhibition effect Category I2 ⁇ 50% Strong inhibition effect Category I3 >50% Limited, absent or negative inhibition effect (promotion of elution of silver)
• a substance which, in the conditions as set forth, has an inhibition strength ratio of less than 50% in the experiment described above is defined as a silver dissolution inhibiting substance and thus corresponds to the Categories I1 or I2.
• the developer composition of the present invention thus comprises, besides the silver complexing agent as defined before, at least one agent preventing silver dissolution characterized in that said agent preventing silver dissolution makes silver content of the developer decrease in an amount of more than 50 % versus in the absence thereof (or otherwise said: has an inhibition strength ratio of less than 50 %, wherein said "inhibition strength ratio" is defined as set forth above), without loss in speed in an amount of more than 0.10 log Exposure after processing in said developer composition, when the dissolution inhibitor is added in an amount in order to get a concentration of 50 mg/l.
• said agent preventing silver salt dissolution preferably corresponds to the general formula (II) wherein Z represents atoms necessary to form a substituted or unsubstituted 5- or 6-membered hetero-aromatic ring, provided that the said hetero-aromatic ring is not substituted by a solubilizing group having a pK a of 7 or less, and M is selected from the group consisting of hydrogen, a group providing a thiolate anion under alkaline processing conditions and a charge compensating counterion for the said thiolate anion.
• the said hetero-aromatic ring is a 5-membered hetero-aromatic ring and in a still more preferred embodiment the said hetero-aromatic ring is selected from the group consisting of triazoles, thiadiazoles, imidazoles and benzimidazoles.
• Silver complexing agents tend to perform better in the silver complexing experiment described above when the concentration of the silver complexing substance is increased. From a practical point of view however an increase in the concentration of the silver complexing agent does not necessarily improve the performance with respect to sludge formation. Due to an increased amount of complexing agents in the developer, the amount of eluted silver will also increase. If the stability of the complex is insufficient or if the amount of complexing agent present is too low to stabilize the increased amount of silver, there is often a decrease in performance with respect to sludge in that sludge formation is not prevented as desired.
• a silver elution or dissolution inhibiting agent present in a specific developer thereby causing a suitable effect with respect to the prevention of sludge formation and no sensitometric effect is called a suitable substance when in the experiment described above, it has an inhibition strength ratio of less than 50% and when it moreover causes a sensitometric loss in sensitivity (measured at a density of 1.0 above fog) of less than 0.10 log (Exposure), wherein said Exposure is the product I x t, representing Exposure I ntensity and Exposure t ime, upon addition of 50 mg/l of the developer.
• the concentration of 50 mg/l refers to the concentration as added to the fresh developer or present in the seasoned developer and not to the concentration in the developer replenisher.
• the combined action of inhibitor and complexant in the developer according to the present invention is explained as follows.
• the inhibitor minimizes the amount of silver ions dissolved or washed out from the film material.
• the complexing agent prevents the reduction of the eluted silver ions to silver and further to silver sludge formation.
• the inhibitors moreover are limiting the amount of silver ions washed out, and thereby also reduce the amount of complexing agents to be added in order to stabilize the silver ions in the used developer solution.
• the silver elution promoting properties of the complexing agents are thus limited by the use of a suitable inhibitor.
• the complexing substance in the developer composition is present in a concentration range between 10 and 2000 mg/l and, more preferably, in a concentration range between 25 and 500 mg/l.
• the developer composition according to the present invention has, in running equilibrium conditions, a molar ratio of silver complexing agent to silver of more than 10:1.
• said developing agents are selected from the group consisting of hydroquinone, l-ascorbic acid, iso-ascorbic acid, reductic acid, 1-phenyl-3-pyrazolidine-1-ones (phenidones), salts and derivatives thereof.
• Said l-ascorbic acid, iso-ascorbic acid, reductic acid are the more preferred forms from the ascorbic acid type developers according to the formula (III)
• This formula corresponds with (iso)ascorbic acid.
• iso-ascorbic acid and l-ascorbic acid are both preferred.
• This formula corresponds with tetramethyl reductic acid.
• the compound(s) according to the formula (V) preferably is (are) present in the developer solution in an amount comprised between 1 g and 100 g per litre, although a preferred amount of from 20 up to 50 g per litre is sufficient in many cases.
• reducing precursor compounds have, e.g., been described in WO's 94/3834 and 94/16362.
• ascorbic acid is not merely used in the developer as an antioxidant as e.g. described in WO 93/12463, in JP-A's 4428673 and 55149936, in GB 1,266,533 and in US-A's 3,865,591; 4,756,997 and 4,839,259 and in the literature as, e.g., J. Am. Chem. Soc., 60 (1938), p. 99 and p. 2084; 61 (1939), p. 442; 64 (1942), p. 1561, 65 (1943), p. 1489; 66 (1944), p. 700 and 104 (1982), p. 6273.
• said antioxidant or agent preventing oxidation is selected from the group consisting of a sulfite salt, l-ascorbic acid, iso-ascorbic acid, reductic acid, salts and derivatives and combinations thereof.
• a combination of high amounts of ascorbic acid type compounds and low amounts of sulfite is therefore highly preferred as the presence of sulfite normally leads to undesirable odours in the processing.
• Low amounts of sulfite as e.g. disclosed in EP-A 0 738 400 are therefore preferred: amounts of less than 0.4 mole per liter of developer are satisfactory in order to prevent oxidation by air oxygen.
• the photographic developer solution thus comprises as an agent preventing oxidation sulfite present in a free sulfite concentration below 0.4 M.
• the developer comprises, as auxiliary developing compounds, one or more 1-phenyl-3-pyrazolidine-1-one or 1-phenyl-5-pyrazolidine-1-one, commonly known as "phenidone" compound.
• a preferred phenidone compound used in the method of the present invention is 4,4'-hydroxymethyl-methyl-1-phenyl-3-pyrazolidine-1-one, which is present in amounts of from 0.5 g up to 5 g/litre of developer.
• said preferred phenidone compound is present in lower amounts as has been disclosed in US-A 5,296,342.
• said developer composition is substantially free from any polyhydroxybenzene compound, as e.g. hydroquinone, analogues and/or derivatives therefrom.
• the developer contains pH buffering agent(s), wherein said agents are selected from the group consisting of carbonates, phosphates and borates and combinations thereof. More particularly carbonate buffers applied may be those described in EP-A's 0 565 459 and 0 736 802 (together with borate) and in US-A's 5,648,205 and 5,738,979; whereas borate buffers may be those as described in GB-A 2,292,813 and in US-A's 5,702,875; 5,756,271 and 5,853,964 and phosphate buffers as in US-A's 5,585,610; 5,744,279; 5,858,612 and 5,876,907.
• 98201862 filed June 5, 1998, in particular for photographic materials having silver halide, coated in an amount, expressed as an equivalent amount of silver nitrate of less than 6 g/m 2 that the said material has a buffering capacity of less than 6 mmole/m 2 , preferably of less than 4 mmole/m 2 and even more preferably less than 2.5 mmole/m 2 , wherein said buffering capacity is defined as the amount of alkali, expressed in mmole/square meter required to bridge across pH differences between the material and the developer.
• the processing making use of a developer composition according to the present invention proceeds in a total dry-to-dry processing time of less than 100 seconds.
• the developer of the present invention is not restricted to the processing of materials coated with such low amounts of silver halide and that also silver halide materials rich in coated amounts of silver, as e.g. double-side coated materials for non-destructive testing purposes having an amount of silver up to 20 g per sq.m. and per side of the support, said amount of silver being expressed as an equivalent amount of silver nitrate, which have been disclosed e.g. in EP-A 0 698 817.
• the developer composition is buffered between a value of from 9.0 up to 11.0 by buffering compounds having a concentration of from 0.3 up to 1.0 mole/litre and more preferably from 0.3 up to 0.7 mole/litre.
• Particularly suitable buffering compounds in the developer composition are carbonates as has also been shown in EP-A 0 565 459, wherein the use of ascorbic acid developers with high concentrations of carbonate buffering is illustrated.
• the high carbonate level provides a high degree of pH buffering and also provides aeration protection via reduced oxygen solubility in the developer solution.
• a compound having an ⁇ -ketocarboxylic acid structure (as oxalic acid, tartaric acid, citric acid, gluconic acid or derivatives thereof) in an amount of not more than 3 g per litre is present in the said fixer solution while starting processing or in the said fixer replenisher.
• pH of the developer replenisher In order to compensate during processing for a decrease of pH due to the oxidation of ascorbic acid type developing agents to oxalic acid it is recommended to provide pH of the developer replenisher to be higher as e.g. in EP-A 0 573 700 and in US-A 5, 869,218 and more particularly about 0.5 higher than the developer itself as in US-A 5,503,965; although depending on the composition of the developer pH differences of 0.1 to 0.3 pH units may be sufficient as disclosed in US-A 5,738,979. In the alternative mixtures of two pyrazolidones may compensate for pH drop as has been suggested in EP-A 0 588 408.
• Ascorbic-acid type developers used in the method of the present invention preferably have a pH in the range from 9-11, but lower values as e.g. in US-A's 5,702,875; 5,756,271; 5,853,964 and 5,858,610 are not excluded.
• Alkalizing agents providing the desired pH are e.g. those described in US-A 5,821,041.
• the developer solution has a regeneration rate of less than 150 ml/m2 while the pH of the developer solution in running equilibrium conditions is between 9.5 and 9.9, with a pH difference between the seasoned developer and the developer replenisher between 0.3 and 0.6.
• a method of processing a black-and-white silver halide photographic material has thus, according to the present invention, also been provided wherein said method comprises the steps of developing, fixing, rinsing and drying, and wherein in running equilibrium conditions a developer composition according to the present invention as disclosed hereinbefore is used in the developing step.
• said developer composition is replenished with same developer composition in an amount of less than 200 ml/m2, and even more preferably in an amount of less than 150 ml/m2.
• the present invention clearly provides a developer for use in the of processing black-and-white light-sensitive silver halide photographic materials, although the target is more severe for the processing with less sludge formation when having in the light-sensitive layer(s) of the said materials photosensitive emulsions rich in silver chloride, wherein said developer is preferably an ascorbic acid type developer used in a processing which is performed at low replenishment rates (less than 150 ml/m 2 ) in order to get a stable or constant sensitometry, even over long working periods with low total amounts of materials to be developed, with moreover the specific feature that the said material having low coating amounts of silver halide has a buffering capacity of less than 6 mmole/m 2 .
• the calcium content is about 0.4 %, which corresponds with about 100 mmole/kg, measured at the end of the preparation process of inert gelatin.
• Complex-bound calcium ions strongly decrease the electric potential carried by gelatin.
• Substantially "calcium free gelatin” is thus defined as gelatin with a calcium content at a level below 40 ppm which corresponds with the analytical detection limit.
• recommended amounts of calcium present in materials processed when making use of a developer composition according to the present invention are less than 10 mg/sq.m. as in US-A 5,723,267, more preferably of less than 5 mg/sq.m. and still more preferably of less than 3 mg/sq.m..
• Materials suitable to be processed in a processing cycle, making use of a developer composition according to the present invention are light-sensitive black-and-white silver halide photographic material being single-side or double-side coated materials, coated on a subbed support with one or more light-sensitive silver halide emulsion layers, wherein said halide is selected from the group consisting of chloride, bromide and iodide and mixtures thereof and said emulsion comprises crystals having a habit selected from the group consisting of a ⁇ 100 ⁇ tabular, a ⁇ 111 ⁇ tabular and a cubic habit and mixtures thereof as in BE 93001438, in EP-A's 0 288 949, 0 528 480, 0 555 897, 0 573 373, 0 574 331, 0 592 616, 0 614 111, 0 622 668, 0 581 065, 0 678 772, 0 704 750, 0 709 730, 0 724 193, 0
• the said light-sensitive silver halide emulsions mentioned hereinbefore, present individually or as a mixture of different emulsions, can be present in one or more adjacent layers at one side or at both sides of a support material and grains or crystals present therein may be cubic grains (whether or not with rounded corners as a consequence e.g. of use of grain growth modifiers, such as e.g.
• the said light-sensitive silver halide emulsions present individually or as a mixture of different emulsions may be present in one or more adjacent layers at one side or at both sides of the support material and grains or crystals present therein and may be ⁇ 111 ⁇ or ⁇ 100 ⁇ tabular grains rich in silver bromide (more than 50 mole % of bromide) or rich in silver chloride (more than 50 mole % of chloride).
• Said tabular grains preferably account for at least 50 % of the total projective surface area of all grains, more preferred for at least 70 % and still more preferred for at least 90 %, further normally have an average crystal diameter (equivalent circular diameter leading to an equal total flat surface as the preferred hexagonal ⁇ 111 ⁇ or rectangular ⁇ 100 ⁇ grain) of from 0.3 to 3.0 ⁇ m, more preferably from 0.5 to 2.5 ⁇ m and still more preferably from 0.5 to 1.5 ⁇ m, for an average thickness of the tabular grain from 0.05 up to 0.30 ⁇ m, more preferably from 0.05 to 0.25 ⁇ m and still more preferably from 0.06 to 0.20 ⁇ m.
• an average crystal diameter equivalent circular diameter leading to an equal total flat surface as the preferred hexagonal ⁇ 111 ⁇ or rectangular ⁇ 100 ⁇ grain
• Average aspect ratios of the ⁇ 111 ⁇ or ⁇ 100 ⁇ tabular grains obtained after calculation from the ratio of diameter to thickness measured for each grain are in the range 2:1 to 100:1, more preferably from 5:1 to 50:1 and still more preferably from 5:1 to 20:1 or even from 8:1 to 20:1.
• Variation coefficients calculated over grain diameters or thicknesses are normally less than 0.40, more preferably less than 0.30 and even more preferably in the range from 0.10-0.20, thereby being indicative for the degree of homogeneity of the grain distribution in an emulsion.
• a crystal habit modifier being a habit stabilizer
• Preferred crystal habit modifiers which are useful in the preparation of ⁇ 111 ⁇ tabular grains for use in the method of the present invention have e.g.
• Iodide ions can be provided by using aqueous solutions of inorganic salts thereof as e.g. potassium iodide, sodium iodide or ammonium iodide. Iodide ions can also be provided by organic compounds releasing iodide ions as has e.g. been described in EP-A's 0 561 415, 0 563 701, 0 563 708, 0 649 052 and 0 651 284 and in WO 96/13759.
• iodide ions provided by organic agents releasing iodide ions are preferred such as mono iodide acetic acid, mono iodide propionic acid, mono iodide ethanol and even hydrogels containing iodide ions, capable to generate iodide ions.
• radiographic materials as e.g. double-side coated materials for chest imaging - see US-A's 5,595,864; 5,693,370 and 5,811,229; and EP-A's 0 678 772 and 0 770 909 - or single-side coated materials for mammography as disclosed e.g. in EP-A 0 874 275 and in US-A 5,449,599)
• laser recording materials as e.g. hardcopy materials as described in EP-A 0 610 608 and in US-A 5,712,081
• micrographic materials as e.g. those described in US-A 5,523,197 and in EP-A's 0 634 691, 0 634 692 and 0 634 693 .
• Time Silver concentration AAS (mg/l) 0 mg/l of compound CC-2 250 mg/l of compound CC-2 1 week ⁇ 1.0 17.1 3 weeks ⁇ 1.0 14.0 6 weeks ⁇ 1.0 3.4 9 weeks ⁇ 1.0 ⁇ 1.0
• Complexing agent C-2 stabilizes the silver ions present in the developer for a period of approximately 3 weeks. After 3 weeks silver starts to precipitate and starts to cause sludge formation.
• Comparative examples without solubilizing group the formulae or which have been represented above do not show a significant improvement with respect to the "complex stability ratio" if compared with a reference sample without complexing agents (----).
• Introduction of suitable stabilizing groups clearly improves the stability of silver ions present in the developer.
• Example 6 An experiment similar to the experiment in Example 1 was performed. In this case however amounts of silver and complexing agent were varied.
• the silver concentration in the silver nitrate solution was varied from 0.0005 mole/l up to 0.0040 mole/l, resulting in a total amount of silver added from 15 to 120 mg/l.
• the concentration of complexing agents was varying from 0 to 2000 mg/liter. As preferred complexing agent use was always made from compound C-1.
• the Table 6 lists the concentration of the silver nitrate solution, the total amount of silver added (in mg/l), the amount of complexing agent C-1 added (in mg/l) and the molar ratio of complexing agent to silver. In the said Table 6 also the amount of silver measured in the supernatant fluid after 3 weeks and the relativetempoual amount of silver in the solution after 3 weeks has been summarized. When the relative amount is close to 0, all silver has been precipitated.
• the relative amount When the relative amount is close to 100%, this means that all silver ions are still in solution (only a limited amount or even no precipitation has taken place).
• the molar ratio of complexing agent to silver must be larger than a factor of 5 (for the time of 3 weeks as set forth hereinbefore). The smaller the ratio, the less stable is the solution. If the ratio of complexing agent to silver is higher than 10, the stability is much better.
• the molar ratio of complexing agent to silver should preferably exceed a value of 5:1. The lower this value the less stable the solution with the silver complexing agent.
• a tabular ⁇ 111 ⁇ silver chloroiodide emulsion was prepared as follows, starting from the solutions given hereinafter:
• a nucleation step was performed by introducing solution A and solution B1 simultaneously in dispersion medium C both at a flow rate of 30 ml/min during 30 seconds. After a physical ripening time of 15 min during which the temperature was raised to 70 °C and 97.5 g of gelatin and 1500 ml of water were added and the mixture was stirred for an additional 5 minutes.
• a growth step was performed by introducing by a double jet during 66 minutes solution A starting at a flow rate of 7.5 ml/min and linearly increasing the flow rate to an end value of 37.5 ml/min, and solution B1 at an increasing flow rate as to maintain a constant mV-value, measured by a silver electrode versus a saturated calomel electrode (S.C.E.), of +92 mV.
• S.C.E. saturated calomel electrode
• a further amount of 0.8 mole % of iodide was added at the end of the preparation stage by addition of a KI-solution.
• a ⁇ 111 ⁇ tabular silver chloroiodide emulsion was thus obtained the average equivalent circular crystal diameter of which was 1.25 ⁇ m and the average thickness of which was 0.17 ⁇ m.
• Chemical ripening agents were gold thiocyanate, sodium thiosulphate as a source of sulphur and toluene thiosulphonic acid was used as predigestion agent.
• the amounts of each chemical ripening were optimized in order to obtain an optimal fog-sensitivity relationship after 2 hours at 57°C.
• the resulting photographic material contained per side an amount of silver halide corresponding to 4.5 grams of AgNO 3 per m 2 and an amount of gelatin corresponding to 3.55 g/m 2 .
• the density as a function of the light dose was measured and therefrom were determined the following parameters:
• the processing was run in the the test developer the composition of which has been given hereinbefore in Table 3. To the developer, different amounts of complexing agents were added and developing was followed by fixing in the hardener free test fixer the composition of which has been given hereinafter in Table 7, further followed by rinsing.
• the whole processing cycle was run in a Curix HTU 330 processing machine, marketed by Agfa-Gevaert N.V. . The total processing cycle was run in 60 s at 35°C as developing temperature.
• Test Fixer -Ammonium thiosulphate 60 % solution, wherein 1 ml comprises 0.778 g) 710 ml -Sodium metabisulphite 80 g -Sodium acetate 130 g -Acetic acid 31 ml pH ready-for-use (after dilution 1+3) 4.90
• the silver content in the samples was determined immediately afterwards by AAS.
• the silver content after 3 and 6 meters of film processing has been shown in the next Table 9.
• the inhibition strength ratio which is preferably as low as possible, is about 23 %, which means that inhibition by the compound according to the formula I-1 is about 4 times stonger than the inhibition in its absence (without inhibiting compound I-1 the inhibition strength ratio is 100 %).
• the silver complexing agents according to the present invention form soluble silver complexes and are expected to show, to a certain extent, silver ion elution properties. Said elution properties are evaluated in the same type of experiment as the evaluation of the inhibiting properties of the inhibitors (see therefore Examples 5 and 6).
• Example 8 shows the influence of inhibitor depletion in a situation where the processing is performed by making use of a replenisher.
• fresh developer is added on the basis of the amount of film processed (e.g. 200 ml/m2), with an optionally time and temperature related oxidation (stand-by) regeneration.
• the inhibitors clearly tend to show larger sensitometric effects than the complexing agents in particular for concentrations above 200 mg/l.
• the developer replenisher solution had the same composition as the developer apart from a higher pH (10.25 instead of 9.65) and for the presence of extra 180 mg/l of compound I-1, with a replenishing rate of 165 ml/m2.
• Number of m2 F S G start 0.265 1.53 3.38 5 0.257 1.53 3.58 10 0.253 1.54 3.58 20 0.250 1.54 3.43 30 0.255 1.55 3.52 40 0.268 1.56 3.40 60 0.283 1.57 3.16 80 0.259 1.58 3.07 100 0.261 1.60 3.13 120 0.271 1.59 3.05
• the concentration in the replenishing solution was 180 mg/l, the actual concentration in the steady state developer was appreciably lower (25 mg/l).
• This example shows that a combination of a complexing agent and an inhibitor perform better when both of them are present.
• the inhibition experiment was performed using the test developer containing moreover a combination of complexing agent C-1 and inhibitor I-3.
• Sample 1 should be considered as comparative example as no complexing agent and no inhibitor were added.
• I-2 (mg/l) C-1 (mg/l) Silver level (mg/l) Sludge 1 comp 0 0 30.2 NOK 2 comp 200 0 8.6 NOK 3 comp 0 200 76.1 NOK 4 inv 200 100 16.8 OK 5 inv 200 300 20.7 OK 6 inv 200 600 17.2 OK 7 inv 300 100 3.9 OK 8 inv 300 300 6.5 OK 9 inv 300 600 13.9 OK 10 inv 500 100 1.1 OK
• a complexing agent tends to stabilize silver ions, but when too high amounts of silver are eluted, the concentration of complexing agent is not high enough to provide enough complexation and resulting anti-sludge action. Additional increase of the concentration of complexing agent will further make the amount of washed out silver increase.
• the processor used was a Fuji Cepros-P processor.
• the developer starting solution was the same as the test developer given hereinbefore with in addition thereto 300 mg/l of inhibiting compound I-2 and 300 mg/l of complexing compound C-1.
• the replenishing solution had following composition. Composition of the developer replenisher.
• the replenishing amount was approximately 165 ml/m2 of a ready-for-use solution.
• the developer was provided as a concentrate (1+1) in order to achieve the desired developer composition after dilution in the processor.
• the hardener free fixer concentrate described hereinbefore was used.
• a film material having ⁇ 111 ⁇ tabular silver bromo(iodide) grains was prepared as follows. Emulsions comprising said grains were prepared as follows.
• A1 at a rate of 7.5 ml/min.
• B1 at a rate of 7.6 ml/min.
• A1 and B1 were added during 2675 seconds at a linearly increasing rate going from 7.5 up to 15 ml/min. for A1 and from 7.6 up to 15.21 ml/min. in order to maintain a constant UAg potential of + 10 mV in the reaction vessel.
• A1 was added during 263 seconds at a rate of 7.5 ml/min. in order to increase the UAg value to 60 mV.
• the film material comprising the emulsions prepared hereinbefore was prepared and coated as follows. Before coating each emulsion was stabilized with 1-p-carboxy-phenyl-5-mercapto-tetrazole and after addition of the normal coating additives the solutions were coated simultaneously together with a protective layer containing 1.3 g gelatine per m 2 per side on both sides of a polyethylene terephthalate film support having a thickness of 175 ⁇ m.
• Table 19 represents the silver level in the developer solution in the processor tank as well as the visually observed sludging level. From the said Table 19 it becomes clear that even after running a substantial amount of film, there is little silver deposit in the developer solution in the tank and sludge level is judged to be excellent (++). Examination of the developer solution one week later is confirming the results with respect to sludge as they remain excellent.
• Example 12 The present example is similar with Example 12. It is illustrative for a comparison made between a material rich in silver bromide (AgBr-Film) as described in Example 12 and a material material rich in silver chloride (AgCl-Film) described in Example 4, when both materials are developed in the test developer the composition of which has been given in the same Example 4 and wherein said developer contains ascorbic acid as main developing agent. Additives added thereto have been given in the Table 21 given hereinafter.
• AgCl-Film (comp.) 12.5 30.2 After 1 hour AgCl-Film + 300 mg I-2/300 mg C-1/l 1.2 2.4 > 3 weeks AgBr-Film (comp.) 7.6 13.0 After 1 hour AgBr-Film + 300 mg I-2/300 mg C-1/l 0.7 1.2 > 3 weeks
• the AgBr-film is superior with respect to sludging if compared with the material rich in silver chloride.
• the addition of the preferred complexing agent and of the preferred inhibitor provides a substantial improvement in both cases.

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