EP0514450B1

EP0514450B1 - Photographic recording material provided with an absorbing layer for photographic speed reduction

Info

Publication number: EP0514450B1
Application number: EP91904108A
Authority: EP
Inventors: Anthony D. Gingello; Richard David Lucitte
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1990-02-06
Filing date: 1991-02-04
Publication date: 1994-04-20
Anticipated expiration: 2011-02-04
Also published as: DE69101778T2; WO1991012562A1; JP2892832B2; EP0514450A1; JPH05504007A; DE69101778D1

Abstract

An absorbing layer is described for photographic recording materials which provides safe roomlight handling under lighting conditions which include ultraviolet radiation.

Description

PHOTOGRAPHIC RECORDING MATERIAL PROVIDED WITH AN ABSORBING LAYER FOR PHOTOGRAPHIC SPEED REDUCTION

The present invention relates to a photographic recording material and more particularly to a photographic recording material which contains an absorbing layer.
Absorbing layers are known in the photographic art. They are used selectively to screen undesired radiation from coming into contact with one or more underlying photosensitive layers. For example, colloidal silver layers are used between blue sensitive and green sensitive layers in color photographic recording materials in order to prevent unwanted blue light from reaching underlying green and red sensitized layers.
A colloidal silver layer is also known to be used on a photographic recording material as an overcoat layer in order to correct color reproduction. Where colloidal silver layers are used they are generally removed from the photographic material during processing by first being converted into silver halide in a bleaching step and then being dissolved and removed in a fixing bath.
U. S. Patent 4,052,215 describes the use of soluble iodide compounds in non-light sensitive colloidal silver filter layers in order to reduce formation of contact fog in photographic recording materials. This technique has the drawback of also requiring a bleaching step to convert colloidal silver to silver halide for subsequent removal during photographic processing.
U. S. Patent 4,818,659 proposes the use of two photosensitive silver halide layers, each having at least 80 mol % of silver chloride, for safe light protection against ultraviolet radiation. The silver halide emulsion layer with greater photosensitivity is coated closer to the support and at least one of the silver halide layers requires the presence of both a hydrazine compound and a dye which has an absorption between about 400 nm and 500 nm. However, this technique poses problems with the use of dyes. For example, dyes are relatively difficult to remove from a photographic material. Dyes tend to accumulate in and contaminate developer solutions thereby causing stain as well as developer instability problems. Also, the presence of a dye frequently causes loss of maximum density in the final image.
U. S. Patent 4,873,181 describes a silver halide photographic material comprising a support, a silver halide emulsion layer overlying the support, and an auxiliary layer containing non-light-sensitive silver halide grains having an average grain size of not more than 0.5 µm which can overlie the emulsion layer. The purpose of the auxiliary layer is to provide high covering power, improved graininess and improved development stability.
Although the photographic art has recognized a need to reduce the speed of photosensitive materials in order to permit roomlight handling and increased safelight handling time while preserving desired maximum density and contrast values, there is still a need to meet these objectives in a photographically acceptable manner.
Accordingly, it is an object of the present invention to provide a photographic recording material which has reduced photographic speed obtained without the need for stain producing dyes, which provides high maximum density and image contrast values and which is suitable for roomlight handling.
According to the present invention there is provided a photographic element comprising (1) a support, (2) a photosensitive silver halide emulsion layer, and (3) a hydrophilic colloid radiation-absorbing layer, separate from said emulsion layer, which provides reduced photographic speed; characterized in that said radiation-absorbing layer is (A) incapable of forming therein a developable latent image and (B) comprised of desensitized silver halide grains dispersed in the hydrophilic colloid binder; said silver halide grains (a) being doped with a desensitizing amount of a transition metal coordination complex containing one or more nitrosyl or thionitrosyl ligands and a transition metal chosen from groups 5 to 10 inclusive of the simplified periodic table of elements published in "Chemical and Engineering News", p.26, February 4, 1985, (b) having a grain size of from 0.01 µm to 4 µm, and (c) being present in said radiation-absorbing layer in an amount of from 50 mg/m2 to 10 g/m2.
The absorbing layer used in this invention is capable of reducing the speed of a photosensitive layer contained in a photographic recording material without causing loss of either maximum density values or desired high contrast values. The absorbing layer permits safe roolight handling of photographic recording materials under lighting conditions which include fluorescent illumination, due to its absorption capability of ultraviolet radiation.
A preferred radiation absorbing layer is capable of absorbing radiation below a wavelength of about 530 nm, is capable of being removed during photographic processing, lends itself to silver recovery, is capable of reducing the photographic speed of the recording material and which preserves maximum density and contrast values, but which is incapable of forming therein a developable latent image.
The absorbing layer can be positioned on either side of the support depending upon the transparency of the support with respect to actinic radiation. Since the purpose of the absorbing layer is to impart safelight handling properties to the photographic recording material, its location within the photographic material is determined by this objective. One common position in a photographic recording material is over a photosensitive silver halide layer in the direction toward the illuminating light source.
The absorbing layer comprises silver halide grains of reduced photosensitivity dispersed in a hydrophilic colloid. The concentration of the silver halide in the absorbing layer is from about 50 mg/m² to about 10 grams/m² having a particle size of from 0.01 µm to about 0.4 µm. Preferably, the silver halide grains are present in the absorbing layer in an amount of from about 0.5 grams/m² to about 3 grams/m². Most preferably the grains have particle sizes between about 0.05 µm and 0.2 µm.
The type of silver halide used in the absorbing layer may include silver chloride, silver bromide, silver iodide or mixed silver halides such as, for example, silver chlorobromide, silver bromoiodide or silver chlorobromoiodide. The silver halide grains can be of any morphology so long as the grain size is within the range of specifications noted above. While silver halides of various types can be employed, the preferred halide is silver bromide.
The fine grained silver halide used in the present invention can be prepared by using methods known in the art. For example, the methods described in P. Glafkides, Photographic Chemistry, Vol. 1, pp 365-368 (1958), or in Mees and James, The Theory of the Photographic Process, p 36 (1966) are useful in this respect.
Also, the fine grained silver halide can be prepared by the methods as described in U.S. Patent Nos. 3,801,326 and 3,737,017. Further, the so-called Lippmann type emulsion which contains extremely fine grained silver halides (having a diameter of 0.1 micron or less) can be employed. These Lippmann emulsions can be obtained by precipitation of silver halides in the presence of a compound, for example a heterocyclic mercapto compound as described in British Patent No. 1,204,623, a heterocyclic mercapto precursor compound as described in West German Patent Application (OLS) No. 2,161,044 or compounds as described in U.S. Patent Nos. 3,661,592 and 3,704,130.
In order to determine the size of fine grained silver halide employed in the present invention, conventional methods can be used. For example, an electron microscope can be used to obtain a photograph of the fine grained silver halide. From the photograph both grain size and diameter can be determined using conventional means.
As noted above the silver halide grains are dispersed in a hydrophilic colloid. The preferred colloid is gelatin, for example, alkali treated gelatin derived from cattle bone or hide or acid treated gelatin derived from pigskin. Gelatin derivatives are also useful such as acetylated gelatin and phthalated gelatin.
In addition to using an absorbing layer of this invention having silver halide of the above-specified grain size, the photographic sensitivity of the absorbing layer needs to be reduced in order to eliminate therein any latent image formation. This is accomplished by densensitization of the silver halide utilizing an electron trapping compound. Such a compound is a "dopant" which is a material other than a silver or a halide ion which is contained within the silver halide grain.
The dopant, when utilized within the ranges noted below, causes desensitization of the silver halide thereby eliminating or minimizing latent image formation.
The dopants utilized in desensitizing the silver halide absorbing layer of this invention are transition metal complexes. Such dopants include both the transition metal and its ligands. Together, the ligand and the transition metal are capable of significantly desensitizing silver halide photographic emulsions.
The dopants contained within the silver halide grains employed in an absorbing layer of this invention are transition metal coordination complexes which contain one or more nitrosyl or thionitrosyl ligands and a transition metal chosen from groups 5 to 10 inclusive of the periodic table of elements. Such ligands are described in U.S. Patent 4,933,272 issued June 12, 1990. These ligands have the formula:

where X is oxygen in the case of nitrosyl ligands and sulfur in the case of thionitrosyl ligands.
Preferred dopants utilized in this invention are transition metal coordination complexes having the formula:

[M(NX)(L)₅]_n

wherein:
M is a ruthenium, rhenium, chromium, osmium or iridium transition metal;
X is oxygen or sulfur;
L is a ligand; and
n is -1, -2 or -3.
Typical hexacoordinated transition metal complexes are shown in the table below.
Procedures for beginning with the compounds of Table I and preparing photographic silver halide emulsions benefitted by incorporation of the hexacoordinated transition metal complex can be readily appreciated by considering the prior teachings of the art relating to introducing transition metal dopants in silver halide grains during precipitation thereof. Such teachings are illustrated for example in Research Disclosure I, Vol. 108, April 1973, Item 10801, in Research Disclosure II, Vol. 134, June 1975, Item 13452; in Research Disclosure, Vol. 176, December, 1978; and in Research Disclosure, Vol. 181, May 1979, Item 18155, the disclosures of which are incorporated herein by reference. Research Disclosure is published by Kenneth Mason Publications, Ltd., The Old Harbourmaster's, 8 North Street, Emsworth, Hampshire PO10 7DD, England. Hereinafter, reference to Research Disclosure will be to the date and item number of such publication.
Transition metal complexes having ligands are known to coprecipitate, at least in part, with silver halide grains. The concentration range for use as electron trapping agents to desensitize filter layers to be used in this invention is at least 10⁻⁶ mole/silver mole and preferably is between 10⁻⁶ and 10⁻³ mole/Ag mole.
The desensitized absorbing layer of this invention is capable of providing the capacity of absorbing undesirable actinic radiation between the wavelengths of about 250 nm to about 530 nm. This results in reduced photographic speed of the photosensitive layer. The exact choice of silver halide usage in the absorbing layer will vary depending upon the absorption efficiency of the silver halide in the spectral region of interest.
Photographic recording materials comprising an absorbing layer of the present invention can be either black-white or color. In the latter, there can be a single color or a multicolor photographic material. In a multicolor material color formers known in the art can be used. For example, dye-forming color couplers can be incorporated in the recording materials in the usual manner.
A typical multicolor photographic element comprises a support bearing a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta 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, such as interlayers, overcoat layers, subbing layers, and the like.
The silver halide emulsions employed in the recording material of this invention can be comprised of silver bromide, silver chloride, silver iodide, silver chlorobromide, silver chloroiodide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof. The emulsions can include silver halide grains of any conventional shape or size. Specifically, the emulsions can include coarse, medium or fine silver halide grains. High aspect ratio tabular grain emulsions are specifically contemplated, such as those disclosed by Wilgus et al U.S. Patent 4,434,226, Daubendiek et al U.S. Patent 4,414,310, Wey U.S. Patent 4,399,215, Solberg et al U.S. Patent 4,433,048, Mignot U.S. Patent 4,386,156, Evans et al U.S. Patent 4,504,570, Maskasky U.S. Patent 4,400,463, Wey et al U.S. Patent 4,414,306, Maskasky U.S. Patents 4,435,501 and 4,643,966 and Daubendiek et al U.S. Patents 4,672,027 and 4,693,964. Also specifically contemplated are those silver bromoiodide grains with a higher molar proportion of iodide in the core of the grain than in the periphery of the grain, such as those described in GB 1.027,146; JA 54/48,521; U.S. 4,379,837; U.S. 4,444,877; U.S. 4,665.012; U.S. 4,686,178; U.S. 4,565,778; U.S. 4,728,602; U.S. 4,668,614; U.S. 4,636,461; EP 264,954. The silver halide emulsions can be either monodisperse or poly-disperse as precipitated. The grain size distribution of the emulsions can be controlled by silver halide grain separation techniques or by blending silver halide emulsions of differing grain sizes.
Sensitizing compounds, such as compounds of copper, thallium, lead, bismuth, cadmium and Group VIII noble metals, can be present during precipitation of the silver halide emulsion.
The silver halide emulsions can be surface-sensitive, i.e., emulsions that form latent images primarily on the surfaces of the silver halide grains, or internal latent image-forming emulsions, i.e., emulsions that form latent images predominantly in the interior of the silver halide grains. The emulsions can be negative-working emulsions, such as surface-sensitive emulsions, or unfogged internal latent image-forming emulsions, or direct-positive emulsions of the unfogged, internal latent image-forming type, which are positive-working when development is conducted with uniform light exposure or in the presence of a nucleating agent.
Surface sensitization can also be accomplished using noble metals (e.g., gold), middle chalcogens (e.g., sulfur, selenium, or tellurium), and reduction sensitizers, employed individually or in combination. Typical chemical sensitizers are listed in Research Disclosure, 1978, Item 17643, cited above, Section III.
The silver halide emulsions can be spectrally sensitized with dyes from a variety of classes, including the polymethine dye class, which includes the cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri-, tetra-, and polynuclear cyanines and merocyanines), oxonols, hemioxonols, styryls, merostyryls, and streptocyanines. Illustrative spectral sensitizing dyes are disclosed in Research Disclosure, 1978, Item 17643, Section IV.
Suitable vehicles for the emulsion layers and other layers of elements of this invention are described in Research Disclosure, 1978, Item 17643, Section IX and the publications cited therein.
The photographic elements can be coated on a variety of supports as described in Research Disclosure, 1978, Item 17643, Section XVII and the references described therein.
The following examples will serve to illustrate the present invention but they are not to be construed as in any way limiting the scope of the invention. Unless otherwise indicated, all parts, percents and ratios are by weight.

Example I:

The following solutions were used to prepare a silver bromide absorbing layer.

Precipitation: 34.12ℓ H₂O, 1043 g gelatin, 40°C
Kettle Soln. I
AgNo₃ Soln. II: 16.75 ℓ H₂O, 16,615 g AgNo₃, 40°C
KBr Soln. III: 18.02 ℓ H₂O, 5,950 g KBr, 40°C
Ruthenium Soln. IV: 200.00 mℓ H₂O, 2.74 g K₂Ru(NO)Br₅, 21°C

Solutions II, III, and IV were added simultaneously at a constant rate to kettle solution I. The kettle environment was controlled at 60 MV and ph = 2.9 during the majority of the precipitation procedure. Solutions II and III concluded flow at 35 minutes, whereas solution IV terminated flow at 5 minutes. Soluble salts were removed from the silver halide emulsion and gelatin was added. pH and vAg, were adjusted to 6.0 and 91 mv, respectively. The resulting cubic emulsion was monodispersed with a mean grain size of .086 µm. The emulsion contained 63 mg of K₂Ru(NO)Br₅/mole Ag, 39.6 g gelatin/mole Ag, and 43.5 moles of AgBr.
The photographic light sensitive material used in this invention was a cubic .15 µm monodispersed AgCl emulsion doped with 20 mg K₂Ru(NO)Br₅/mole silver. The emulsion was prepared in a similar fashion to the absorbing layer emulsion with vAg controlled at 140 mv.
The AgBr absorbing layer emulsion was coated over the photographic light sensitive AgCl emulsion which was coated on a 4 mil estar support. The absorbing layer emulsion was coated at varying silver laydowns, 1356 mg gel/m², and contained both surfactants and 107 mg/m² of the hardener bis(vinylsulfonylmethyl)-ether (BVSM). The photographic light sensitive AgCl emulsion was coated at 3336 mg Ag/m², 2722 mg gel/m², and contained 4-hydroxy-6- methyl-2-methylmercapto-1,3,3A,7-tetraazindene, and 130 mg/m² of BVSM.

Sample Exposing

Sensitometry
Samples were exposed in contact with a type - M carbon stepwedge having increments of 0.10 density. Radiation for exposure was provided by a 500 watt iron doped metal halide lamp.

Halftone Exposing

Halftone reproduction was accomplished by exposing a square dot pattern of 50% dot area in vacuum contact with exposures provided by an iron doped metal halide lamp.
Strips of the above photosensitive material were processed in KODAK RA200 Rapid Access Developer in a KODAK K65A processor for 32 seconds at 30 degrees C.
Results are reported in the following table.
In addition to the sensitometric and halftone speed reduction effects of the silver halide absorbing layer it can be seen from the above Tables that the safelight handling time with various silver halide absorbing layer levels is extended beyond that which would be explained by speed reduction only and is proportional to the amount of silver halide in the absorbing layer. This effect is the result of the high differential absorption of the AgBr in the spectral region below about 350 nm. Film sensitivity in this region of the spectrum is not useful for graphic arts applications since this region is filtered by glass and image construction materials in the exposing device. Since construction materials vary in their UV absorption in this region, the film's insensitivity below about 350 nm reduces the exposure effects of multiple source imaging assembly materials.

Claims

A photographic element comprising (1) a support, (2) a photosensitive silver halide emulsion layer, and (3) a hydrophilic collid radiation-absorbing layer, separate from said emulsion layer, which provides reduced photographic speed; characterized in that said radiation-absorbing layer is (A) incapable of forming therein a developable latent image and (B) comprised of desensitized silver halide grains dispersed in the hydrophilic colloid binder; said silver halide grains (a) being doped with a desensitizing amount of a transition metal coordination complex containing one or more nitrosyl or thionitrosyl ligands and a transition metal chosen from groups 5 to 10 inclusive of the simplified periodic table of elements published in "Chemical and Engineering News", p.26, February 4, 1985, (b) having a grain size of from 0.01 µm to 4 µm, and (c) being present in said radiation-absorbing layer in an amount of from 50 mg/m2 to 10 g/m2.
A photographic element as claimed in claim 1 wherein said grains have a size of from 0.05 µm to 0.2 µm and are present in said radiation-absorbing layer in an amount of from 0.5 g/m2 to 3 g/m2.
A photographic element as claimed in claims 1 or 2 wherein said desensitized silver halide is silver bromide.
A photographic element as claimed in any of claims 1 to 3 wherein said radiation-absorbing layer overlies said photosensitive silver halide emulsion layer.
A photographic element as claimed in any of claims 1 to 4 wherein said transition metal coordination complex has the formula:

[M(NX)(L)₅]_n

wherein M is ruthenium, rhenium, chromium, osmium or iridium; X is oxygen or sulfur; L is a ligand; and n is -1, -2, or -3.
A photographic element as claimed in any of claims 1 to 4 wherein said transition metal coordination complex is K₂Ru(NO)Br₅.