This invention relates to filter dyes and their use in photographic elements.
Filter dyes are widely used in photographic elements. Filter dyes may be located in several locations in an element. They may be in a radiation-sensitive layer, an overcoat layer, in a layer adjacent to the radiation-sensitive layer, in an interlayer of a multilayer element, in an undercoat layer adjacent to the support or in a backing layer on the side of the support opposite the radiation-sensitive layer.
When incorporated directly in the radiation-sensitive layer they can function to improve sharpness by absorbing light scattered from one silver halide grain to another. Such dyes are referred to as absorber dyes. Filter dyes also function to retard the sensitivity of one light sensitive layer relative to another in a multilayer element. By absorbing some of the exposing radiation the filter dye aids in balancing the sensitivities of all the light sensitive layers.
Filter dyes that function primarily to absorb unwanted radiation due to reflection or refraction from layer interfaces, the layer-support interface, and particularly from the back side of the support, are referred to as antihalation dyes. The layers that contain them are referred to as antihalation layers.
There are other places and purposes for filter dyes and filter layers. For example, a filter layer may be used in or near the overcoat layer to protect the light sensitive layer against radiation from certain spectral regions. In multilayer films where there may be two or more light sensitive layers, it is sometimes necessary to have filter dye interlayers. In duplitizedo materials, such as X-ray films, filter layers are used to reduce crossover exposure of the light sensitive layers. Elimination of crossover exposure is an ideal that is highly desirable but has not yet been fully attained.
A number of problems are associated with filter dyes and filter layers. It is very important that the dyes remain in the layer and not wander or diffuse into the adjacent layers. This often necessitates the presence of a mordant to hold the dye in the layer. It is equally important for the dyes to be completely decolorized and/or removed from the element, usually during processing, after they have performed their function. Dye stability, especially under high temperature and high humidity incubation is also important.
In some photographic elements, it is desirable to absorb unwanted radiation across the entire visible spectrum. In such elements it is not unusual to use up to five filter dyes in a single filter layer to accomplish this desirable objective. Clearly it would be an improvement to reduce the number of filter dyes used in the layers of such elements.
U.S. Patent 3 560 214 discloses dyes comprising a carboxyl and phenyl substituted pyrazoline nucleus linked through a methine group to a dialkyl-aminophenyl group. However these dyes, according to the patent and our own experiments, are migratory.
DE-A 1 909 463 describes, as photographic filter dyes, 2-pyrazolin-5-one arylidene compounds having carboxyl substituents bonded directly to the 2-pyrazolin-5-one ring at the 3-position. These filter dyes, however, can wander from the layers in which they are coated, adversely affecting the light-sensitive silver halide layers of the photographic material.
DD-A 109 455 describes water-soluble carboxy salt-substituted arylidene compounds in photographic filter layers. This reference describes the use of large ballasting groups as substituents on the dye molecules in an attempt to limit wandering of these water-soluble dyes.
DE-A 2 262 794 describes water-soluble arylidene compounds as photographic filter dyes.
Research Disclosure No. 14416, 1976. pages 17-20, describes water-soluble sulfanyl-substituted and sulfo-substituted barbituric acid-containing compounds as filter dyes in photographic layers. The reference describes the preparation of a carboxyphenyl-substituted compound, but it was not coated in a photographic layer. Cyclohexyl substituents appear to be used as ballast groups in an attempt to limit dye wandering of these water-soluble dye compounds.
It is an objective of this invention to provide filter dyes for photographic elements which meet the foregoing requirements for filter dyes, do not cause post process dye stain or migrate from layer to layer and reduce the number of filter dyes needed in a filter layer.
The foregoing objectives are achieved with a solid microcrystalline dispersion of a dye having the formula:
- R represents hydrogen, substituted or unsubstituted alkyl of 1 to 4 carbon atoms, or benzyl,
- Rl and R2 each independently represents substituted or unsubstituted alkyl or aryl, or taken together with R5, R6, N, and the carbon atoms to which they are attached, represent the atoms needed to complete a julolydyl ring,
- R3 represents H, or substituted or unsubstituted alkyl or aryl,
- R5 and R6 each independently represents H, or R5 taken together with R1, or R6 taken together with R2, represent the atoms necessary to complete a carbocyclic ring such as tetrahydroquinoyl, and m is 0 or 1.
In a preferred embodiment, the dyes useful in the practice of the invention are merostyryl arylidenes having the formula:
- R represents hydrogen, substituted or unsubstituted alkyl of 1 to 4 carbon atoms, or benzyl,
- R1 and R2 each independently represents substituted or unsubstituted alkyl or aryl, or taken together with R5, R6, N, and the carbon atoms to whatever they are attached, represent the atoms needed to complete a julolydyl ring,
- R3 and R7 each independently represents H, substituted or unsubstituted alkyl, aryl, alkoxy, hydrogen, or acetamido,
- R4 represents substituted or unsubstituted alkyl, alkoxycarbonyl, aryl, acyl, or amido,
- R5 and R6 each independently represents H, or R5 taken together with R!, or R6 taken together with R2, represent the atoms necessary to complete a carbocyclic ring,
- R8 is C02H or NHS02R9 wherein R9 is substituted or unsubstituted alkyl or aryl,
- x is 1 or 2, and
- n is 0 or 1.
The carboxyphenyl substituent on A is important in immobilizing the dye at coating pH's of 5-7.
The acyl, alkyl and alkoxy groups may contain from one to twenty carbons. Examples of such groups include acetyl, benzoyl, methyl, ethyl, propyl, methoxy carboxyl, ethoxy carboxyl, butoxycarboxyl, fluoralkyl, dodecyl, and octadecyl. The aryl groups may contain from six to twenty carbons, which may be further substituted with a wide variety of groups. Examples of such substituted and unsubstituted aryl groups including phenyl and napthyl with alkyl substituents as defined above.
Microcrystalline dispersions of the dyes of this invention leave no residual post-processing stain in processed photographic elements. Polymeric mordants are not needed to immobilize the dyes, as immobilization is achieved without mordants. Complete and irreversible dye removal during processing is achieved. Broadened and shifted absorption is obtained which makes the compositions particularly suitable for filter or antihalation applications. Their broadened absorption bands are particularly useful in reducing the number of dyes needed in a single element to absorb unwanted radiation. Another advantage is superior dye stability when subjected to high temperature and high humidity incubation.
Examples 1-3 below relate to the preparation of representative dyes of the above formulas. Variations on the procedures described to obtain other dyes of these formulas, such as those of the examples and Table I and II below are within the skill of the practicing synthetic chemist. Procedures for making such dyes are described in "The Cyanine Dyes and Related Compounds", Frances Hamer, Interscience Publishers, 1984.
Abbreviations used in the examples are: NMR = nuclear magnetic resonance, IR = infrared, HCI = hydrochloric acid, EtOH = ethanol, MeOH = methanol, Et20 = ethyl ether, DMF = dimethylformamide, DM-SO = dimethylsulfoxide, NaOH = sodium hydroxide and mp = melting point.
A solution of sodium nitrite (35.8 g, 0.52 mol) in water (75 ml) was added to a slurry of 5-aminoisophthalic acid (90.6 g, 0.50 mol) in 4.8 molar HCI (500 ml) at 0°C over 15 minutes with stirring. Stirring was continued for one hour at 0-5°C and the slurry was then added to a solution of sodium sulfite (270 g, 2.2 mol) in water (1.21) all at one time, with stirring, at 2°C. The resulting homogeneous solution was heated at 50-60°C for 45 minutes. Concentrated HCI (60 ml) was added and the reaction mixture was heated further at 90°C for one hour. After cooling to room temperature, another portion of concentrated HCI (500 ml) was added. The solid was isolated by filtration and washed on a funnel with acidified water, EtOH and lignoin in succession. The off-white solid was dissolved in a solution of NaOH (76 g, 1.85 mol in 600 ml water). This solution was subsequently acidified with glacial acetic acid (166 ml, 3.0 mol) to yield a thick slurry. This was isolated by filtration, washed on the funnel with water, EtOH, and lignoin in succession, and thoroughly dried in a vacuum oven at 80°C, and 10 mm Hg. The mp was above 300°C. The NMR and IR spectra were consistent with the structure for 5-hydrazino-1,3-benzenedicarboxylic acid. The product gave a positive test for hydrazine with Tollens' reagent.
A slurry composed of the product 5-hydrazino-1,3-benzenedicarboxylic acid (64.7 g, 0.33 mol), ethyl- acetoacetate (50.7 g, 0.39 mol) and glacial acetic acid (250 ml) was stirred and refluxed for 22 hours. The mixture was cooled to room temperature and the product that had precipitated was isolated by filtration, washed with water, EtOH, Et20, and lignoin in succession and thoroughly dried in a vacuum oven at 80°C and 10 mm Hg. The mp of the solid was above 310°C. The NMR and IR spectra were consistent with the assigned structure. The product gave a negative test with Tollens' reagent. The C,H, and N elemental analyses were in agreement with those calculated for the empirical formula.
A slurry composed of 1-(3,5-dicarboxyphenyl)-3-methyl-2-pyrazoline-5-one (44.6 grams, 0.17 mol), 4-dimethylamino-benzaldehyde (26.9 grams, 0.18 mol) and EtOH (500 mL) was heated at reflux for three hours. The reaction mixture was chilled in ice and the resulting crude orange product was isolated by filtration and washed with EtOH (200 mL). The product was purified by three repetitive slurries of the solid in acetone (1.4 I) at reflux and filtering to recover the dye. The mp of the product was above 310°C. The NMR and IR spectra were consistent with the structure assigned. The C, H, and N elemental analyses were in agreement with those calculated for the empirical formula.
A slurry composed of 1-(4-carboxyphenyl)-3-methyl-2-pyrazolin-5-one (21.8 g, 0.10 mol), 4-dimethyl- amino-benzaldehyde (14.9 g, 0.10 mol) and EtOH (250 ml) was heated at reflux for two hours. The reaction mixture was cooled to room temperature, resulting in a crude orange product which was isolated by filtration. The product was then washed with ether and dried. The product was purified further by making a slurry of the solid in EtOH (700 ml) at refluxing temperature and filtering the slurry to recover the dye. The treatment was repeated. The mp of the product was above 310°C. The NMR and IR spectra were consistent with the structure assigned. The C, H, and N elemental analyses were in agreement with those calculated for the empirical formula.
1-(4-Carboxyphenyl)-3-methyl-2-pyrazolin-5-one (2.18 g 0.010 mol), 4-dimethylaminocinnamaldehyde (1.75 g, 0.010 mol) and glacial acetic acid (10 ml) were mixed together to form a slurry. It was heated to reflux with stirring, held at reflux for five minutes and then cooled to room temperature. EtOH (20 ml) was added to the reaction mixture, which was heated again to reflux, held there for five minutes, and cooled to room temperature. The product was isolated by filtration, washed in succession with ethanol and lignoin, and dried. The reaction was repeated twice on the same scale and the products obtained were all combined. They were treated further by first slurrying in refluxing EtOH (150 ml), isolating the solid by filtration while hot, and then slurrying in refluxing MeOH (200 ml) and isolating it again, while hot, by filtration. The mp was 282-284°C. The NMR and IR spectra were consistent for the structure assigned. The C,H, and N elemental analyses were in agreement with those calculated for the empirical formula of the dye.
The dyes prepared in Examples 1-3 and other dyes useful in the practice of the invention prepared with similar properties are listed in Tables I and II along with their absorption maxima (in methanol solution with a stabilizing amount of triethylamine) and extinction coefficients.
The above dyes in Tables I and II may also have sulfonamido substituents instead of the carboxyl sub- stitutents, such as:
The dyes useful in the practice of the invention are in the form of a solid particle microcrystalline dispersion for incorporation into a layer such as a hydrophilic colloid layer coated on a photographic element. The microcrystalline dispersion can be formed by precipitating the dye in the form of a dispersion and/or by well-known milling techniques, e.g., ball-milling, sand-milling, or colloid-milling the dye in the presence of a dispersing agent. The dye particles in the dispersion preferably have a mean diameter of less than 10 Itm and more preferably of less than 1 [Lm. The dye particles can be conveniently prepared in sizes ranging down to 0.01 µm or less.
Multicolor elements contain dye image-forming units sensitive to each of the three primary regions of the spectrum. Each unit can be comprised of a single emulsion layer or of multiple emulsion layers sensitive to a given region of the spectrum. The layers of the element, including the layers of the image-forming units, can be arranged in various orders as known in the art. In an alternative format, the emulsions sensitive to each of the three primary regions of the spectrum can be disposed as a single segmented layer, e.g., as by the use of micro-vessels as described in U.S. Patent 4,362,806.
A typical multicolor photographic element would comprise a support bearing a cyan dye image-forming unit comprised of at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green- sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler and a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler. The element can contain additional layers, other filter layers, interlayers, overcoat layers, subbing layers, and the like.
In the following discussion of suitable materials for use in the emulsions and elements of this invention, reference will be made to Research Disclosure, December 1978, Item 17643, published by Kenneth Mason Publications, Ltd., The Old Harbourmaster's, 8 North Street, Emsworth, Hampshire P010 7DD, ENGLAND, the disclosures of which are incorporated herein by reference. This publication will be identified hereafter by the term "Research Disclosure".
The silver halide emulsions employed can be either negative-working or positive-working. Suitable emulsions and their preparation are described in Research Disclosure Sections I and II and the publi cations cited therein. Suitable vehicles for the emulsion layers and other layers are described in Research Disclosure Section IX and the publications cited therein.
In addition to the couplers the elements can include additional couplers as described in Research Disclosure Section VII, paragraphs D, E, F and G and the publications cited therein. These couplers can be incorporated in the elements and emulsions as described in Research Disclosure Section VII, paragraph C and the publications cited therein.
The photographic elements or individual layers thereof, can contain brighteners (see Research Disclosure Section V), antifoggants and stabilizers (see Research Disclosure Section VI), antistain agents and image dye stabilizer (see Research Disclosure Section VII, paragraphs I and J), light absorbing and scattering materials (see Research Disclosure Section VIII), hardeners (see Research Disclosure Section XI), plasticizers and lubricants (see Research Disclosure Section XII), antistatic agents (see Research Disclosure Section XIII), matting agents (see Research Disclosure Section XVI) and development modifiers (see Research Disclosure Section XXI).
The photographic elements can be coated on a variety of supports as described in Research Disclosure Section XVII and the references described therein.
Photographic elements can be exposed to actinic radiation, typically in the visible region of the spectrum, to form a latent image as described in Research Disclosure Section XVIII and then processed to form a visible dye image as described in Research Disclosure Section XIX. Processing to form a visible dye image includes the step of contacting the element with a color developing agent to reduce developable silver halide and oxidize the color developing agent. Oxidized color developing agent in turn reacts with the coupler to yield a dye.
The following examples illustrate the use of solid particle dye dispersions in filter layers of photographic elements of the invention.
The dyes were subjected to ball-milling according to the following procedure. Water (21.7 ml) and a 6.7% solution of Triton X-200@ surfactant (TX-200@) (2.65 g) (available from Rohm & Haas) were placed in a 60 ml screw-capped bottle. A 1.00 g sample of dye was added to this solution. Zirconium oxide (ZrO) beads (40 ml) (2 mm diameter) were added and the container with the cap tightly secured was placed in a mill and the contents were milled for four days. The container was removed and the contents added to a 12.5% aqueous gelatin (8.0 g). The new mixture was placed on a roller mill for 10 minutes to reduce foaming and the resulting mixture was then filtered to remove the ZrO beads.
A spreading agent, surfactant 10G@, and a hardener (bis(vinyl-sulfonylmethyl)ether) were added to the dye-gelatin melt prepared as described in the preparation of the microcrystalline dye dispersions. A melt prepared from the latter mixture was then coated on polyethylene terephthalate support to achieve a dye coverage of 0.32 g/m2, gelatin coverage of 1.60 g/m2, a spreading agent level of 0.096 g/m2 and a hardener level of 0.016 g/m2. Spectral data were obtained from an analysis of the coatings on a spectrophotometer interfaced with a computer. A summary of the data obtained is in Table III where the dye numbers correspond to those of Tables I and II. All absorption maxima and half band width (HBW) data are expressed in nanometers (nm). Three sets of absorption data are presented: λ-max and HBW of the coating containing the ball-milled dispersion of the dye, λ-max and HBW of the same coating at pH 10, the pH at which the merostyryl chromophore is fully ionized, and X-max and HBW of the dye in methanol solution.
In addition to the data in Table III, absorption spectra of the coatings for dyes 1, 2, 3, 6, 10 and 11 were made. Comparison of the curves of coatings containing microcrystalline dispersion of a particular dye with the same dye in a coating at pH 10 showed the microcrystalline dispersion absorbance maximum was shifted compared to the solution spectra. This provides an unexpected advantage for use as a filter dye.
Referring to Table III, it is clear that the absorption spectra of the coatings containing the microcrystalline dye dispersion are broader than for the same dyes in solution or in coatings at pH 10. Thus, microcrystalline dispersions of dyes according to the invention are suitable for filter applications where broad visible light filtration is required. This broad absorption also serves to reduce the number of dyes needed for a particular filter application.
The coated microcrystalline dye dispersions prepared as described in the previous examples were evaluated for dye mobility. Samples of the coatings were given a five minute distilled water wash. The results for four of the dyes, 1, 2, 3 and 5, are shown in Table IV. The coatings were also evaluated for post processing stain following processing in the Kodak Prostaro processor used commercially to process microfilm, subjecting the elements to a development step at a pH of 11.4 for 30 seconds. These results are also included in Table IV.
which exhibited a λ-max of 450 nm and a bandwidth of 117 nm before any washing processing.
Table IV shows that no dye density was lost by the dyes dispersed and coated as described in the previous examples due to the distilled water wash. This shows that there was no dye wandering from layer to layer. The comparison dye, on the other hand, exhibited severe washout, indicating a high degree of dye wandering.
Table IV also demonstrates dramatically the complete removal of the microcrystalline dispersion dyes on Prostar@ processing at room temperature. No residual stain is left. The same results were observed when the coatings were processed with Kodak X-Omat@ processing, which is used commercially to process x-ray film, subjecting the elements to a development step at a pH of 10.3 for 30 seconds. This is an improvement over other known latex imbibed yellow filter dyes which are incompletely removed by these processing conditions.
For Examples 28 and 29, microcrystalline dispersions of dyes of the formula
Dye 25 had a λ-max of 449 nm and a bandwidth of 121 nm before washing or processing. Dye 26 had a À,-max of 453 nm and a bandwidth of 97 nm before washing or processing. The results in Table V indicate that the photographic compositions of the invention containing Dyes 25 and 26 do not wander during the water wash, but decolorize completely after photographic processing. The comparison Dye 24, however, washes out during the water wash, indicating severe wandering.
The utility of microcrystalline dispersions of dyes according to the invention, in combination with other dyes, is illustrated with dyes 1 and 5 of Table I. The dispersions were prepared as in examples 5-19. These dispersions were each coated as a component of an antihalation layer in a multilayer format, along with a cyan filter dye, bis[1-(4-carboxyphenyl)-3-methyl-2-pyrazolin-5-one-(4)]pentamethineoxonol. The coatings, 1 to 4 in Table VI, were evaluated for dye stain after processing. The emulsion layer was a chemically and spectrally sensitized 0.25 micron cubic silver bromoiodide (3% iodide) emulsion layer coated to achieve silver coverage of 1.45 g/m2 and gelatin coverage of 1.56 g/m2. The gelatin coverage in the antihalation layer was 1.88 g/m2. The levels of dyes 1 and 5 and of the cyan dye are indicated in Table VI. The gelatin coverage in the overcoat layer was 1.56 g/m2. The coatings were exposed to a tungsten light source in a sensitometer, developed, fixed and washed in the Kodak Prostar@ process and dried.
The coatings containing microcrystalline dispersions of dyes 1 and 5 and the cyan filter dye, at the levels shown in Table I, exhibited no residual dye stain and provided significantly high light absorption.