A method of reducing variability in sensitometry under both high and low activity conditions development of a colour photographic material

Abstract: A process of processing an imagewise exposed colour photographic material comprising at least one silver halide emulsion layer having associated therewith a dye image-forming coupler and which contains in a layer thereof one or more compounds of the general formula: which release an electron transfer agent (ETA) under alkaline conditions, which process includes the step of treating the material in an alkaline colour developer solution. The preferred ETA's are pyrazolidinones of a type which reduce sensitometric variability in the developed colour image in both high and low activity conditions.

Description: Field of the Invention This invention relates to a method of reducing variability in sensitometry under both high and low activity conditions development of photographic silver halide colour materials. Another related patent application is European publication no. 0 679 942. Background of the Invention Our European publication no. 0 561 860 describes a method of developing an imagewise exposed silver halide colour material to provide sensitometric results of reduced variability which comprises carrying out colour development in the presence of one or a combination of black-and-white silver halide developing agents (termed herein electron transfer agents or ETAs) incorporated in said silver halide colour material in an inactive form from which the active form is released during processing, whereby development in low activity conditions is accelerated while that in high activity conditions is decelerated thus reducing the variability in the density versus LogE curve (the characteristic curve) caused by changes in process variables such as time, temperature, colour developing agent concentration and bromide ion concentration. Model examples having the black-and-white silver halide developing agent present in the developer solution are described. The specification also mentions that when the black-and-white silver halide developing agent is incorporated in the photographic material it is preferably in a form which is inactive until processing takes place. For example it could be inactivated by a blocking group which is hydrolysed off when the material is immersed in the developing solution (which is usually alkaline). Our European publication no. 0 551 509 describes a method of processing a colour photographic silver halide material comprising a compound including a photographically useful group (PUG) and a blocking group, enabling more rapid release of the PUG upon processing. Problem to be Solved by the Invention The problem with known hydrolysable blocked pyrazolidinone developing agents (BETAs) is that they only unblock at the required pH if the compound is rather unstable. If the compound is stable enough not to break down in the material they do not unblock fast enough (or at all) to be useful. Summary of the Invention According to the present invention there is provided a method of reducing variability in sensitometry under both high and low activity conditions, wherein in high activity conditions development of a colour photographic material is decelerated and in low activity conditions development is accelerated, wherein the colour photographic material comprises at least one silver halide emulsion layer having associated therewith a dye image-forming coupler and which contains in a layer thereof one or more electron-transfer agent releasing compounds of the general formula: wherein T 1 and T 2 individually are releasable timing groups; n and m individually are 0 or 1, at least one of n and m being 1; ETA is a group which is released as an electron transfer agent and has one of the formulae wherein in type (1) R 9 and R 10 are each hydrogen or a C 1-3 alkyl or alkoxy group or a C 1-7 substituted alkyl or alkoxy group, R 11 and R 12 are each hydrogen or a C 1-3 alkyl or hydroxyalkyl group, and wherein at least one of R 9 and R 10 is not hydrogen except where R 11 is an acyloxyalkyl or aryloxyalkyl group when each of R 9 and R 10 can be hydrogen; in type (2) R 9 and R 10 are each hydrogen or a C 1-3 alkyl group and R 11 and R 12 are each a C 1-3 alkyl or hydroxyalkyl group and in type (3) R 9 to R 12 are each hydrogen or an unsubstituted or substituted C 1-12 alkyl or alkoxy group, wherein the total number of carbon atoms in R 9 to R 12 is at least 4; wherein the one or more compounds of formula (I) include an ETA of type (1) alone or a combination of either type (1) and type (3) or type (2) and type (3); x is 0, 1 or 2; R is substituted or unsubstituted alkyl or aryl or a photographic ballast group replacing a ring hydrogen; y is 0, 1, 2, or 3; R 1 is unsubstituted or substituted alkyl; Z is located in the ring not adjacent to the ketocarbonyl group and is a group having one of the formulae: each R 2 is individually a substituted or unsubstituted alkyl, aryl or heterocyclic group, or a carbamoyl, carbonamido, sulfamoyl, sulfonamido, ester or acid group; R 3 is H; ―SO 2 ―R 4' ; substituted or unsubstituted alkyl or aryl or a photographic ballast group; R 4 is unsubstituted or substituted alkyl, or aryl; R 4' is unsubstituted or substituted alkyl, or aryl, or and R 5 and R 6 individually are hydrogen, or unsubstituted or substituted alkyl or aryl; or the compound has one of the structures: which process includes the step of treating the material with a photographic colour developer composition containing a binucleophile. Advantageous Effect of the Invention The colour photographic materials used or useful in the invention show the advantages of improved performance in the colour developer where variations in process conditions have less effect than previously on sensitometric performance, particularly in the case of multilayer colour materials. In the present invention not only are the low activity conditions accelerated by the presently used ETA releasers but also high activity conditions are decelerated thus leading to less variation in sensitometric results under both high and low activity conditions. This means that the spread of the characteristic curves as in Figs 3-13 of the accompanying drawings is compressed. It has been found, in particular, that the presence of the ETA releaser reduces variability caused by variations in time and temperature of development, pH, bromide ion concentration and colour developing agent concentration in the colour developer solution. The reduced risk of sensitometric variations further means that replenishment rates can be reduced thus resulting in less overflow and effluent. The often-needed bromide ion removal from the developer solution may also be avoidable. Brief Description of the Drawings Figures 1-13 in the accompanying drawings illustrate the results of the working Examples below. Detailed Description of the Invention The alkyl groups represented by any of R to R 6 may be alkyl groups having 1 to 25 carbon atoms, (C 1-25 ) preferably 1 to 6 carbon atoms (C 1-6 ). Of the substituted groups, the substituents may be halogen, alkyl, alkoxy, acyloxy, aroyloxy, keto, ether, ester, sulfonamido, sulfamoyl, carbonamido, or carbamoyl groups. The binucleophile to be contained in the colour developer composition can, for example, be hydroxylamine, hydrogen peroxide or hydrazine, all of which may be substituted, or a salt thereof. The colour developer composition may contain a water-soluble electron-transfer agent, such as a pyrazolidinone. The ETA groups have the general formula: wherein R 9 to R 12 are as hereinbefore defined. As is known from European publication no. 0 561 860, there are three types of behaviour observed with different types of pyrazolidinone. The reduction of sensitivity to development time is used as an example. Three broad types of behaviour for different ETAs can be observed and these are as follows: Type (1): A reduction of sensitometric spread with a retardation of overdevelopment and an acceleration of the underdevelopment. Type (2): A modest reduction of sensitometric spread with a general acceleration of dye formation. Type (3): A reduction in sensitometric spread with a general retardation of dye formation. The use of Type (2) or Type (3) ETAs alone is not part of the present invention. Type (1) is the preferred behaviour exhibited by the preferred compounds especially when used singly. The present invention also includes the use of combinations of ETAs. Combinations of Type (2) and (3), for example, can give an overall behaviour similar to or better than Type (1). Combinations of Type (1) and (3) also give good results in that the spread of the sensitometric curves is particularly well controlled. It is recognised that the definitions of the above types of ETA are not mutually exclusive. This is because it is difficult to find an appropriate definition which is mutually exclusive. Examples of the three types are given below. Beyond that the skilled worker will be able to determine to which type a particular ETA belongs by carrying out the procedures described herein. Specific examples of the three types of ETA are as follows: Specific examples of BETA compounds to be used in the present invention have the formulae below. They are all type (1) except where specified. The compounds of formula (1) may be incorporated into the photographic materials by methods, in themselves, known. For example they may be dispersed therein in a high-boiling organic solvent, often known as a "coupler solvent". Examples of such solvents are triphenylphosphate, and dibutylphthalate. Normally the coupler is dissolved in the coupler solvent or mixture of solvents and this liquid is dispersed in an aqueous gelatin solution. Sometimes a low boiling solvent is used in the coupler solvent mixture but this is removed after the dispersion has been formed. The present invention is particularly applicable to the processing of colour negative film but is also applicable to other processes, e.g. colour paper. The material to be processed comprises a support bearing at least one silver halide emulsion layer having a colour coupler associated therewith. The term "associated therewith" here takes its normal meaning in art. The coupler may be incorporated in the emulsion layer or in a layer adjacent thereto. The preferred colour materials comprise three dye image forming units each containing one or more emulsion layers having couplers associated therewith and each sensitised to a different region of the spectrum. A typical colour material would contain such units sensitised to blue, green and red light and capable of forming yellow, magenta and cyan image dyes respectively. Examples of colour photographic materials and methods of processing them are described in Research Disclosure Item 308119, December 1989 published by Kenneth Mason Publications, Emsworth, Hants, United Kingdom. The following Examples are included for a better understanding of the invention. EXAMPLE 1 Compound 1 was made into a dispersion in coupler solvent (1) (diethyl lauramide) and solvent (2) (ethyl acetate) in the ratio, (Compound (1):Solvent (1) : Solvent (2)) by weight of 1:2:3. The oil phase was then dispersed in gelatin to give 1.0 % Compound 1, 4.0 % gelatin. Coatings were then made in which compound 1 was coated in a layer underneath a layer containing the silver halide and coupler. This is shown in the table 1 below. The BETA compound was coated in a range of levels 0.0, 0.05, 0.1, 0.2 and 0.4 g/m 2 . The ETA released from the BETA is 4'-methoxyphenylpyrazolidinone. EXAMPLE 2 The coatings of Example 1 were processed in standard C-41 developer, which contains 2g/l of hydroxylamine sulphate(HAS), for the following development times: 1, 2.5, 5 and 8 minutes. In Figure 2 the sensitometric response of the control coating for these four development times is shown. In Figure 3 the effect of the highest coated level of BETA for the same set of development times is shown with the curves from the control plot superimposed. It can be seen that with BETA present the sensitometric spread is reduced. This effect is similar to that shown by adding the ETA to the developer but to a smaller extent. In Figure 4 the extent of sensitometric spread is plotted against the coated level of BETA and it can be seen that sensitometric spread is reduced as the level of BETA is increased. EXAMPLE 3 Compound 1 is designed to release the ETA 4'-methoxy-1-phenylpyrazolidinone by the action of the bi-nucleophile, hydroxylamine sulphate (HAS), which is in C-41 developer at 2g/l. Hydroxylamine is present in C-41 developer as an anti-oxidant. In order to demonstrate the action of hydroxylamine in releasing the ETA some C-41 developers were made-up with a range of HAS levels of 0, 1, 2, 6, 24 and 60g/l. The control coating and the one with the highest level of BETA (0.4g/m 2 ) were processed in these developers and the comparisons for HAS levels of 0, 6 and 60g/l are shown in Figures 5, 6 and 7 respectively. It can be seen that without HAS there is almost no effect from the coated BETA, but there is when HAS is present. In Figure 1 the reduction in sensitometric sensitivity is plotted against HAS level in the developer for a BETA (0.4g/m 2 ) containing coating and one without BETA. Here it can be seen that there is a small reduction in sensitometric sensitivity with HAS increase for the coating without BETA but a much greater reduction in the coating with BETA. EXAMPLE 4 The following multilayer structures were prepared. The figures in parentheses are coverages in g/m 2 : where the silver halide is a bromoiodide emulsion with an average 3% iodide. The following variations in the nature, amount and position of the BETA compound(s) and their effect on the sensitometric results illustrated in the Figures specified were as follows: 1. Single BETA in multilayer; Figs. 8 and 9 a. Fig. 8 compares a control with a BETA (Compound 8) incorporated in the anti-halation layer of a multilayer at 1.0g/m 2 . Solid lines are for the red record of the control, dashed lines for the red record with the incorporated BETA. There is a small amount of compression of the spread in sensitometry by the incorporation of the BETA. b. Fig. 9 compares a control with a BETA (Compound 10) incorporated at 0.33g/m 2 in both the fast and slow layers of the red sensitive pack of a multilayer. Solid lines are for the red record of the control and the dashed lines for the red record of the incorporated BETA. There is a moderate compression of the sensitometric spread by incorporation of the BETA. 2. Combinations of BETAs in multilayer; Figs. 10, 11, 12, 13. a. Fig. 10 compares the red records of a control with a BETA (Compound 7) incorporated in the anti-halation layer of a multilayer at 0.5g/m 2 . This is an example of a BETA which releases an accelerating ETA and consequently the dashed curves(BETA) are in the main accelerated relative to solid curves of the control. b. Fig. 11 compares the red records of a control with a BETA (Compound 9) incorporated in the anti-halation layer of a multilayer at 0.5g/m 2 . This is an example of a BETA which releases a retarding ETA and the dashed curves for the BETA are retarded relative to the solid curves for the control. c. Fig. 12 compares the red records of a control with a combination of two BETAs, Compound 7 and Compound 9 incorporated in the anti-halation layer of a multilayer at 0.5g/m 2 each. This is an example of a combination of an accelerating and a retarding BETA. The dashed curves of the BETA coating show that longer development times are retarded and the shorter development times accelerated relative to the solid lines of the control. d. Fig. 13 compares the red records of the example of Fig 12 with an additional 0.4g/l of 4'-methoxy-1-phenyl-3-pyrazolidinone in the developer used for the BETA incorporated coating. In this case the longer development times are retarded and the short development times accelerated to a greater extent than without the ETA in the developer.

Claims: A method of reducing variability in sensitometry under both high and low activity conditions, wherein in high activity conditions development of a colour photographic material is decelerated and in low activity conditions development is accelerated, wherein the colour photographic material comprises at least one silver halide emulsion layer having associated therewith a dye image-forming coupler and which contains in a layer thereof one or more electron-transfer agent releasing compounds of the general formula: wherein T 1 and T 2 individually are releasable timing groups; n and m individually are 0 or 1, at least one of n and m being 1; ETA is a group which is released as an electron transfer agent and has one of the formulae; wherein in type (1) R 9 and R 10 are each hydrogen or a C 1-3 alkyl or alkoxy group or a C 1-7 substituted alkyl or alkoxy group, R 11 and R 12 are each hydrogen or a C 1-3 alkyl or hydroxyalkyl group, and wherein at least one of R 9 and R 10 is not hydrogen except where R 11 is an acyloxyalkyl or aryloxyalkyl group when each of R 9 and R 10 can be hydrogen; wherein in type (2) R 9 and R 10 are each hydrogen or a C 1-3 alkyl group and R 11 and R 12 are each a C 1-3 alkyl or hydroxyalkyl group and in type (3) R 9 to R 12 are each hydrogen or an unsubstituted or substituted C 1-12 alkyl or alkoxy group, wherein the total number of carbon atoms in R 9 to R 12 is at least 4; wherein the one or more compounds of formula (I) include an ETA of type (1) alone or a combination of either type (1) and type (3) or type (2) and type (3); x is 0, 1 or 2; R is substituted or unsubstituted alkyl or aryl or a photographic ballast group replacing a ring hydrogen; y is 0, 1, 2, or 3; R 1 is unsubstituted or substituted alkyl; Z is located in the ring not adjacent to the ketocarbonyl group and is a group having one of the formulae: each R 2 is individually a substituted or unsubstituted alkyl, aryl or heterocyclic group, or a carbamoyl, carbonamido, sulfamoyl, sulfonamido, ester or acid group; R 3 is H; ―SO 2 ―R 4' ; substituted or unsubstituted alkyl or aryl or a photographic ballast group; R 4 is unsubstituted or substituted alkyl, or aryl; R 4' is unsubstituted or substituted alkyl, or aryl, or and R 5 and R 6 individually are hydrogen, or unsubstituted or substituted alkyl or aryl; or the compound has one of the structures: which process includes the step of treating the material with a photographic colour developer composition containing a binucleophile. A method as claimed in claim 1 in which the compound of formula (I) has an ETA group of the general formula (4) or (5) wherein R 9 to R 12 are as defined for type (1). A method as claimed in either of the preceding claims in which the compound of formula (I) has an ETA group of general formula (4) or (5) wherein R 9 to R 12 are as defined for type (1) and is in combination with a compound of formula (I) having an ETA group of general formula (4) or (5) wherein R 9 to R 12 are as defined for type (3). A method as claimed in claim 1 in which the compound of formula (I) has an ETA group of general formula (4) or (5) wherein R 9 to R 12 are as defined for type (2) and is in combination with a compound of formula (I) having an ETA group of general formula (4) or (5) wherein R 9 to R 12 are as defined for type (3). A method as claimed in any of claims 1-4 in which the colour developing composition contains a water-soluble electron transfer agent. A method as claimed in any of claims 1-5 in which the electron transfer agent is a pyrazolidinone.

Inventors: PROEHL GARY S, TSOI SIU CHUNG, TWIST PETER JEFFERY, PROEHL, GARY S., TSOI, SIU CHUNG, TWIST, PETER JEFFERY, Proehl, Gary S., Eastman Kodak Co., TSOI, SIU CHUNG, C/O KODAK LTD., Twist, Peter Jeffery, c/o Kodak Ltd.
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1995
Main classification: G03C7
IPC codes: G03C7