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
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
  • G03C1/047—Proteins, e.g. gelatine derivatives; Hydrolysis or extraction products of proteins
• • 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
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
  • G03C2001/0818—Calcium ion content or calcium compound

Definitions

• a method of processing has been described for a light-sensitive black-and-white silver halide photographic material, said method providing less tendency to sludge formation.
• 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.
• the above mentioned objects are realized by providing a method of processing of a light-sensitive black-and-white silver halide photographic material comprising the distinct steps of developing, fixing, rinsing and drying, wherein during said processing said developer comprises, besides one or more developing agent(s), one or more agent(s) preventing oxidation thereof and agent(s) providing pH buffering in running equilibrium conditions during said processing, at least one agent preventing silver dissolution and at least one silver complexing agent, characterized in that
• the developer solution may be any of the solutions which is used in order to develop a 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).
• 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 “seasoned developer” is the same as the developer in "running equilibrium conditions”.
• 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 an equilibrium or seasoned state has been reached.
• the method of the present invention comprises the step of mixing of developer starter solution and fixer replenishing solution in a developer unit or tank of the said processor.
• 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 developing composition by the method 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 method of processing of a light-sensitive black-and-white silver halide photographic material comprising the distinct steps of developing, fixing, rinsing and drying, wherein during said processing said developer comprises, besides one or more developing agent(s), one or more agent(s) preventing oxidation thereof and agent(s) providing pH buffering in running equilibrium conditions during said processing, at least one agent preventing silver dissolution and at least one silver complexing agent , characterized in that
• 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.
• a silver complexing agent as defined in the statement of the invention makes silver content of the developer increase in an amount of more than 1 mg per liter per mmole of said complexing agent.
• the silver complexing ability of said silver complexing agent used in the method of the present invention is measured by a method containing following steps:
• a substance which, in the conditions given above, has a complex stability ratio of more than 70% (thus belonging to the categories C1 or C2) as described in the experiment above is defined as a (suitable) silver complexing substance .
• 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 behavior of the substances under investigation.
• a satisfactory complexing agent is an agent which has a complex stability ratio of more than 70%, wherein said complex stability ratio is determined after a time of 3 weeks during which said developer composition has been left unstirred as a ratio of silver content in supernatant fluid to total amount of silver originally present in running equilibrium conditions.
• said satisfactory 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 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 developing 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 developing 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 developing solution.
• a similar (blank) experiment is performed in the absence of the chemical compound or substance under investigation.
• the inhibition strength is then defined by comparing the silver content with and without the substance under investigation in the developing 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 developing solution containing the sludge inhibiting substance and the silver content in the developing solution without the said substance after processing 3 m of film in the above defined conditions.
• the agent preventing silver dissolution thus has an inhibition strength ratio of less than 50 %, wherein said inhibition strength ratio for a combination of said silver halide photographic material and said developer in running equilibrium conditions is defined as ratio of silver content in the said developer containing said agent preventing silver halide dissolution and silver content in the said developer without the said agent, after processing two times 3 m of an unexposed photographic material having a width of 48 mm and transporting it through the said developer solution at a speed of 23 cm/min.
• the inhibitors are classified as represented in Table 2 hereinafter.
• Inhibition Strength Ratio ( 3 m ) Appreciation or Classification 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.
• a number of substances actually promotes the elution of silver ions out of the film material (negative inhibition effect). If these substances do not stabilize the eluted silver, they tend to promote the occurrence of sludge, and are therefore undesired. If these substances form a silver complex which is stable enough to stabilize the (increased) amount of eluted silver, this component may nevertheless be effective in preventing silver sludge formation.
• the developer 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.
• the agent preventing silver salt dissolution in the developing step preferably corresponds to the general formula (IV) 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.
• a developer composition for use in the method of processing according to the present invention should have a ratio by weight of complexing agent to silver present in said composition in running equilibrium processing conditions during processing is more than 10:1.
• 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 as disclosed in the method of 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.
• said silver complexing agent(s) is(are) present in a concentration between 10 and 2000 mg/l, whereas said agent preventing silver dissolution is present in a concentration between 25 and 500 mg/l.
• developing agents are members selected from the group consisting of hydroquinones, 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) wherein in the formula (III) each of A, B and D independently represents an oxygen atom or NR ' 1 ;
• This formula corresponds with (iso)ascorbic acid.
• iso-ascorbic acid and l-ascorbic acid are both preferred.
• the compound(s) according to the formula (III) 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.
• said method comprises the step of developing in a developing solution, wherein said solution comprises one or more developing agents.
• a developing solution comprises one or more developing agents.
• 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 is substantially free from any polyhydroxybenzene compound, as e.g. hydroquinone, analogues and/or derivatives therefrom.
• said pH buffering agent is 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.
• the said processing further comprises the step of replenishing the developer composition in an amount of less than 200 ml/m2 and, moreover, the said replenishing proceeds with a replenisher having the same composition as the developer composition.
• a replenisher having the same composition as the developer composition.
• 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.
• said processing proceeds in a total dry-to-dry processing time of less than 100 seconds.
• the method 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 solution 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 developing solution 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 developing solution.
• Use of highly buffered ascorbic acid developers has been disclosed e.g. in US-A 5,503,965, wherein the instability of ascorbic acid developers has been tackled not only by the use of highly buffering solutions but in addition by the use of replenisher solutions having a higher pH.
• 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 developing solution has a regeneration rate less than 150 ml/m2 and pH of the developing 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.
• the method according to the present invention it is further preferred that, in order to provide constant sensitometric and physical properties of silver halide photographic materials after rapid processing in solutions, replenished with minimum amounts of said solutions and in order to specifically minimize the differences between the freshly prepared fixer solution and the fixer solution after seasoning that upon starting of the processing the said fixer solution comprises a mixture of a fixer starter solution and a fixer replenisher solution and in that said fixer solution is replenished with the said fixer replenishing solution as disclosed in EP-A 0 851 286.
• said method comprises the step of mixing a fixer starter solution and a fixer replenisher solution in a fixer unit or tank of the said processor.
• the film material to be processed is a light-sensitive black-and-white silver halide photographic material which is a single-side or double-side coated material, coated on a subbed support with one or more light-sensitive silver halide emulsion layers, said halide being selected from the group consisting of chloride, bromide and iodide and mixtures thereof and said emulsion comprising 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, 0 731 382, 0
• the said tabular grains rich in silver chloride are ⁇ 100 ⁇ tabular grains accounting for at least 30% and more preferably at least 50% of the total projective area of all grains, having at least 90 mole% of silver chloride and not more than 1 mole% of silver iodide.
• the said light-sensitive silver halide emulsions present individually or as a mixture of different emulsions are present in one or more adjacent layers at one side or at both sides of the support material and grains or crystals present therein are 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 are present in one or more adjacent layers at one side or at both sides of the support material and grains or crystals present therein are ⁇ 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 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 preferably 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.
• 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 present in the material used in the method of the present invention preferably have a calcium content of 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..
• Dyes absorbing in the blue wavelength region of the visible spectrum for use as spectral sensitizers for cubic and/or tabular silver halide grains can be used as those described in JP-A 01-196031 and in US-A's 4,494,212; 4,952,491 and 5,376,523.
• spectral sensitization as described in EP-A 0 890 873 can advantageously be applied. The same applies to the other regions of the visible spectrum as the green wavelength region (see e.g.
• spectral sensitizers described in EP-A 0 757 286.
• combinations of differing spectral sensitizers may be used as well as mixtures of emulsions being the same or different, wherein each part may be spectrally sensitized with another spectral sensitizer or with another combination of spectral sensitizers.
• Spectral sensitizers having asymmetrical heterocycles may be useful with respect to improvements in residual colouration after processing.
• Suitable supersensitizers are e.g. heterocyclic mercapto compounds containing at least one electronegative substituent as described e.g. in US-A 3,457,078, nitrogen-containing heterocyclic ring-substituted aminostilbene compounds as described e.g. in US-A 2,933,390 and US-A 3,635,721, aromatic organic acid/formaldehyde condensation products as described e.g.
• the black-and-white photographic material may contain several light-insensitive layers at the side of the support carrying said light-sensitive emulsion layer(s), e.g. a protective antistress layer which can be split up into two layers, one of them being an underlying interlayer or an outermost afterlayer coated or sprayed on top of the "basic" protective antistress layer.
• Said protective antistress layer may comprise e.g. one or more organic compounds inhibiting development, like e.g. organic compound(s) inhibiting development is(are) preferably (a) benzotriazole compound(s) as disclosed in EP-A 0 866 362.
• Protective antistress layers present in the materials used in the method of the present invention preferably contain coating aids and coating physical property modifying addenda mentioned in RD's Nos. 36544 and 38957, published September 1994 and 1996 respectively, Chapter IX.
• Antistatic properties are especially preferred in order to prevent blackening after processing in form of sparks etc. due to abrupt decharging of electrostatic charges during production and/or handling before exposure and/or processing. It is highly preferred to add antistatic agents to the protective antistress layer or to an afterlayer coated thereupon as has been described e.g. in EP-A's 0 534 006, 0 644 454 and 0 644 456 and in US-A's 4,670,374 and 4,670,376.
• Abrasion resistance of these outermost layers may be improved as described in US-A's 4,766,059 and 4,820,615.
• Spraycoating of afterlayers has been disclosed e.g. in US-A 5,443,640.
• Non-imagewise blackening may alternatively be due to pressure sensitivity of the silver halide grains. Measures in order to prevent pressure sensitivity may be coating of enhanced amounts of binder as e.g. gelatin. This however is disadvantageous with respect to rapid processing and therefore as an alternative silver halide crystals prepared in silica may offer an alternative as has been disclosed e.g. in EP-A's 0 528 476, 0 649 051 and 0 682 287 .
• one or more subbing layers e.g. filter layers, antistatic agent(s), filter dyes for safety-light purposes etc. may be present.
• intermediate layers eventually containing filter or antihalation dyes that absorb scattering light and thus promote the image sharpness have been described in e.g.
• Backing layers applied to a material having at least one emulsion layer at one side of a light-sensitive silver halide material having emulsion crystals rich in chloride used in the image-forming systems essentially contain as ingredients hydrophilic colloids, one or more antihalation dye(s), matting agent(s), surfactant(s), antistatic agent(s), lubricant(s) and hardening agent(s), said ingredients being same as discussed hereinbefore.
• Amounts of hydrophilic colloids may be chosen in order to prevent curl of the single side emulsion coated material, such as in US-A 5,155,013.
• non-swelling hydrophobic polymers can be used in the backing layer as has e.g. been described in US-A 5,326,686. Further measures to prevent curling have been disclosed e.g. in JP-A's 02-24645; 02-85847 and 02-87138.
• the support of the black-and-white photographic materials comprising silver halide emulsion having crystals, used for X-ray imaging may be a transparent resin, preferably a blue coloured polyester support like polyethylene terephthalate.
• the thickness of such organic resin film is preferably about 175 ⁇ m.
• Other hydrophobic resin supports are well known to those skilled in the art and are made e.g. of polystyrene, polyvinyl chloride, polycarbonate and polyethylene naphthalate.
• the support is further provided with a substrate layer at both sides to have good adhesion properties between the adjacent layers and said support: one or more subbing layers known to those skilled in the art for adhering thereto a hydrophilic colloid layer may be present.
• Suitable subbing layers for polyethylene terephthalate supports are described e.g. in US-A's 3,397,988, 3,649,336, 4,123,278 and 4,478,907.
• a preferred layer arrangement wherein a subbing layer composition comprising as a latex copolymer vinylidene chloride, methylacrylate and itaconic acid has been covered with hydrophilic layers being at least one gelatinous dye containing layer comprising one or more dyes, at least one silver halide emulsion layer, at least one protective antistress layer, and optionally an afterlayer has been described in EP-A 0 752 617.
• hydrophilic layers have a swelling ratio of not more than 200 % and in said hydrophilic layers are coated simultaneously by the slide-hopper coating or by the slide-hopper curtain coating technique.
• suitable supports can be found in RD's Nos. 36544 and 38957, Chapter XV, published September 1994 and September 1996 respectively.
• materials having subbed supports are preferably providing permanent antistatic character thanks to electronic conductivity of polyethylene dioxythiophene (PEDT) as those described in EP-A 0 602 713 and in EP-Application No. 99200496, filed February 22, 1999.
• PEDT polyethylene dioxythiophene
• black-and-white photographic materials can be used such as, for example, X-ray photographic materials, photographic materials for printing, photographic papers, photographic negative films, microfilms, direct positive photographic materials, super fine grain light-sensitive materials (for a LSI photomask, for a shadow mask, for a liquid crystal mask, for diffusion transfer type materials, for heat-developable photographic materials, for high-density digital recording photographic materials, photographic materials for holography, etc.
• said black-and-white silver halide photographic materials are (single-side or double-side coated) radiographic materials or (single-side coated) laser-imaging materials wherein a laser source directed by digital information is "written" on a hard-copy laser film.
• Suitable lasers may be gas lasers or solid state lasers.
• a suitable gas laser a helium/neon gas laser is well-known (absorption maximum 633 nm).
• a solid state laser an infrared laser diode having a more bathochrome absorption maximum at 820 nm may be used, but nowadays also green-and blue-light laser sources are available, as e.g. a YAG-laser.
• a preferred laser imager we refer to the laser imager MATRIX LR 3300, trade name product marketed by Agfa-Gevaert.
• Suitable single-side coated materials for use in the processing of the present invention have e.g.
• Double-side coated materials have e.g. been described in US-A's 5,397,687 and 5,660,966 and in EP-A's 0 678 772 and 0 754 972.
• Useful multilayer assemblies have e.g. been described in EP-A 0 770 909.
• penetrating radiation which is high energy radiation belonging to the class of X-rays, ⁇ -rays and high energy elementary particle radiation, e.g. ⁇ -rays, electron beam or neutron radiation.
• penetrating radiation For the conversion of penetrating radiation into visible light and/or ultraviolet radiation luminescent substances are used called phosphors.
• Light emitted imagewise by intensifying screens as in medical diagnosis irradiates a contacting photographic silver halide emulsion layer film which after exposure is developed to form therein a silver image in conformity with the X-ray image.
• the X-ray film comprises a transparent film support double-side coated with a silver halide emulsion layer. During the X-ray irradiation said film is arranged in a cassette between two X-ray conversion screens each of them making contact with their corresponding silver halide emulsion layer.
• Phosphors suitable for use in the conventional radiographic system must have a high prompt emission on X-ray irradiation and low after-glow in favour of image-sharpness.
• Typical blue-UV emitting phosphors are tantalates and hafnates and fluorohalides of barium and strontium.
• particles a niobium doped, monoclinic M, yttriumtantalate phosphor and particles of an europium doped bariumfluorohalide phosphor are composing the screen.
• Screen/film combinations may be symmetric or asymmetric: this means that screens differing in speed and/or radiation emitted therefrom are differing and/or that there is a difference in speed and/or contrast and/or spectral sensitivity at both sides of the film support.
• processing apparatus In a conventional processing apparatus the sheet material is transported along a generally horizontal feed path, the sheet material passing from one vessel to another usually via a circuitous feed path passing under the surface of each treatment liquid and over dividing walls between the vessels.
• processing machines having a substantially vertical orientation have also been proposed, in which a plurality of vessels are mounted one above the other, each vessel having an opening at the top acting as a sheet material inlet and an opening at the bottom acting as a sheet material outlet or vice versa.
• substantially vertical is intended to mean that the sheet material moves along a path from the inlet to the outlet which is either exactly vertical, or which has a vertical component greater than any horizontal component.
• the apparatus occupies only a fraction of the floor space which is occupied by a conventional horizontal arrangement.
• the sheet transport path in a vertically oriented apparatus may be substantially straight, in contrast to the circuitous feed path which is usual in a horizontally oriented apparatus.
• the straight path is independent of the stiffness of the sheet material and reduces the risk of scratching compared with a horizontally oriented apparatus.
• it is important to avoid, or at least minimize leakage of treatment liquid from one vessel to another and carry-over as the sheet material passes through the apparatus.
• the treatment liquid in one vessel is not contaminated by contents of the adjacent vessels, that is neither by the treatment liquid of the next higher vessel nor by vapours escaping from the next lower vessel.
• the developing cell of the apparatus is a closed cell and the developing liquid contains an ascorbic acid developing agent as has been described in EP-Application No. 96201753, filed June 24, 1996.
• a method of processing photographic sheet material by use of an apparatus comprising a plurality of processing cells so arranged to define a sheet material path through the apparatus, at least one of the cells constituting a developing cell containing a developing liquid, characterized in that the developing cell is a closed cell and the developing liquid contains an ascorbic acid developing agent.
• EP-A 0 819 992 With respect to further characteristics of the processing apparatus suitable for use in the processing method of the present invention we refer to EP-A 0 819 992, wherein it was an object to provide an apparatus in which operating components can easily be replaced without the need for substantial re-programming of the CPU (central processing unit).
• 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 of 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 suitable for use in the processing method of the present invention.
• Example 2 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.
• 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 processed film material was the same material as described hereinbefore.
• 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.
• the processing was run in the developer, the composition of which has been given hereinbefore in Table 3 - see Example 1, followed by fixing in fixer, the composition of which has been given hereinbefore in Table 7 - see Example 4, and rinsing at the indicated temperature of 35°C for a total processing time of 60 s.
• 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 5 The experiment was performed according to the description in Example 5, using non-destructive film material STRUCTURIX D7, trademarked product from Agfa-Gevaert, having huge coating amounts of silver (symmetrical double-side coated material coated at a silver amount, equivalent with 26 g of silver nitrate per square meter and per side).
• Table 20 lists the silver levels after 3 m and 6 m of highly silver coated film have been processed. Without addition of complexing and inhibiting compounds precipitation is formed in the developer within one hour (comp.). When both compounds are added (inv.), sludging is postponed.
• 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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