JPS60260039A - Black/white direct positive photographic element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a direct positive photographic method for forming a silver image containing internal latent image forming silver chloride grains and a maximum density increasing anticapri agent. Regarding elements. Furthermore, the present invention relates to a method of obtaining positives directly from such photographic elements after imagewise exposure.

[Conventional technology]

A photographic element that forms an image with an optical density that is directly related to the radiation received during exposure is said to be negative working.

Positive photographic elements are formed by forming a negative photographic image that is a negative of a first negative, ie, a positive. A direct positive is understood in photography to be a positive that is formed without first forming a negative image. Direct positive photographs are
It is advantageous in providing a simpler approach to obtaining positive photographic images.

Although silver halide photography offers the highest attainable photographic sensitivity for direct positive printing, a surprisingly large number of approaches to direct positive printing exist in the field of silver halide photography. Some of these approaches include James (
James) The Theory of Photography
ry of th@PhotographicProc
@ss), 4th edition p Mac2 Run (Maemllan)
) 19' Section 17.7, @Latent Image Effect [Lsm
ding to Rsversal and Dasen
sltizatlon)”.

Desensitized imaging of internal latent images is known to lead to the highest achievable photographic speeds of the various direct positive silver halide imaging approaches. According to this approach, a silver halide emulsion containing internal latent image-forming silver halide grains that is substantially free of surface fog is used. After imagewise exposure, the no-rodunized silver grains are developed with a surface developer, ie, a developer that will leave the latent image substantially hidden within the no-rodunized grains. At the same time, either by uniform exposure or by the use of a nucleating agent, the silver halide grains are exposed to development conditions that will result in fogging of the surface latent image forming silver halide grains. Under these conditions, internal “latent image-forming” silver rodanide grains that received actinic radiation during imagewise exposure
The remaining internal latent image formation occurs at a slow rate compared to the silver rodanide grains.

As recognized in U.S. Pat. No. 2,497,917, when direct positive imaging is used in desensitizing the internal latent image, certain antifoggants only reduce fog in the region of minimum density. but also increases the maximum concentration. Eventually, this approach gained acceptance in the field of using maximum density increasing antifoggants in internal latent image desensitization direct positive imaging. This particular class of antifoggants is known to be useful whether incorporated directly into photographic elements or into processing solutions such as developer solutions. The application of maximum density increasing antifoggants to a new type of internal latent image desensitization direct positive imaging is described in U.S. Pat. No. 3,761,276 and Research Disclosure.
), Vol. 151, November 1976.

This is illustrated by item 15162. Research 0
Disc closure (R@5earch Dlsel
osure) is a property of Kenneth Mason Publications, Ltd.
lications.

Ltd, ), -/・Old Harper Masters (T
h@O1d Harbormaster's), Hampshire, UK POIO7DD, Emsworth
Published by 8 North Street.

In the following margin [Problems to be Solved by the Invention] Direct positive-working silver halide emulsions have recognized technical disadvantages compared to negative-working silver halide emulsions Internal latent image desensitized image formation is not possible with silver halide emulsions. is the most sensitive approach to positive image formation using direct positive photographic speeds, although direct positive photographic speeds are still not as high as those routinely achieved using negative-working silver halide emulsions. Thus, there is a need in the art to improve the photographic sensitivity of this imaging.

A second drawback of internal latent image desensitization direct positive imaging is the re-inversion (r
This is what happens when there is overexposure.

A schematic illustration of reinversion is given in FIG. 1, which plots density versus exposure. Characteristic curves (formatted to exaggerate the characteristics of the curves to simplify discussion) are shown for direct positive emulsions. When the emulsion is coated as a layer on a support, exposed and processed, a density is produced.

The characteristic curve is the result of plotting various levels of exposure against the corresponding density produced during processing. At exposure doses below level A, underexposure occurs and a maximum density that does not change as a function of exposure is obtained. A
At exposure levels between and B, density changes inversely to exposure so that useful direct positive printing can be achieved. If the exposure is made between the levels indicated by B and C, overexposure will occur. That is, the density stops changing as a function of exposure in this range of exposures. If the subject to be photographed varies locally over a wide range of reflected light intensities, a photographic element containing a direct positive emulsion can be exposed simultaneously in different areas at levels smaller than A and larger than B. However, while the result may still be aesthetically pleasing, detail in both light and dark areas of the subject is lost. If you increase the exposure for this subject and try to pick up the dark detail, you may want to increase it to a level above the bright exposure C. When this happens, you are faced with a second reversal. Since the density is now increasing with direct exposure, areas overexposed beyond level C will appear as a highly undesirable negative image. The useful exposure latitude can be increased by separating the exposure levels, but this is undesirable because it reduces the contrast below the optimal level for most subjects. Reinversion reduction is therefore appropriately directed towards increasing the separation between exposure levels B and C, so that overexposed areas are less likely to produce a negative image. (In actual practice, the various segments of the characteristic curve tend to fall more smoothly than illustrated.) In silver halide photographic elements that form dye images for viewing, the morphology of the developed silver matters little. Not. This is because the silver formed during development is an unwanted by-product of dye formation and is commonly bleached out of the photographic element. However, in black and white photography, common practice relies entirely or partially on developed silver to form a visible image. The form of silver produced during development is
This can have a significant impact on image quality and silver requirements. One measure of the use of silver in black and white imaging is covering power, J.

"Covering power" is expressed in various units in the art, but as used herein is defined as maximum density versus silver (100 cm2).
It is defined as the ratio of the number of grams (grams of weight) multiplied by 100. As is clear from this definition, achieving an increase in the maximum density of the toned image without increasing silver coverage is often expressed succinctly as increasing covering power.

It is an object of the present invention to provide a support and one or more radiation-sensitive emulsion layers containing internal latent image-forming silver halide grains, in which an increase in photographic sensitivity and a broadening of the exposure limit before re-inversion occurs is achieved. and a maximum density increasing antifoggant for forming visible silver images.

[Means to solve the problem]

The above objects are achieved when the photographic element further features the improvement of locating a maximum density increasing antifoggant in the undercoat between the emulsion layer and the support.

The invention is generally applicable to black and white direct positive photographic elements for use in forming visible retained silver images. Photographic elements have one or more radiation-sensitive emulsion layers containing internal latent image-forming silver rhodanide grains coated on a support. To achieve the advantages of this invention, the maximum density increasing antifoggant is located in the undercoat between one or more emulsion layers and the support. For the sake of brevity, this undercoat will be referred to hereinafter as the "antifoggant undercoat."

While in the past maximum density-enhancing "pre-inhibitors" have been placed in the silver rodanide emulsion layer of black-and-white direct positive photographic elements or in their processing solutions, the photographic elements of the present invention incorporate one or more inhibitors. - Positioning these maximum density increasing antifoggants between the rhodanized emulsion layer and the photographic support.In other words:
The antifoggant undercoat is disposed adjacent to the support as well as any radiation sensitive halodanized emulsion imaging layer.

In general, any of the maximum density enhancing antifoggants recognized to be useful in internal latent image desensitization direct positive imaging can be used alone or in combination in the practice of this invention.

Useful maximum density enhancement antifoggants are azoles and azines. Such azoles and azines have 1 group in the azole or azine ring, where R1 represents hydrogen or an alkali-hydrolyzable group. Specific examples of such maximum density increasing antifoggants are U.S. Pat. Nos. 2,497,917 and 3,761,276.
issue and the aforementioned Research Disclosure (R5
5ereh Disclosure) +Item 1
5162 (each incorporated herein by reference).

A particularly preferred maximum density increasing antifoggant is 1°2;
3-) IJ Azoles, including those having a fused aromatic ring structure, such as benzotriazoles. Examples of particularly preferred maximum density increasing 1,2° 3-triazole antifoggants are listed in Table 1.

Table 1 AF-1 benzotriazole AF-25-bromobenzotriazole AF-35-methylbenzotriazole AF-44-nitro-6-chlorobenzotriazole AF-95-= ) lobensotriazole AF-105, 6-dichloropent The Riazole maximum concentration increasing anti-capri agent can be used in any effective amount. Generally, concentrations of 0.1 mole per mole of silver or less are used in the practice of this invention. Maximum density antifoggants, particularly the 1,2.3-) lyazole antifoggants described above, are useful in one or more of the radiation-sensitive silver halide emulsions of a photographic element when no other source of maximum density antifoggant is provided. per mole of silver in the anticapri undercoat below the layer from 5 x 10-' to 0.1 mole, preferably from 10-5
It is incorporated at a molar concentration of 5 x 10-2. When other sources of maximum density increasing antifoggants are provided, the concentration of the maximum density increasing antifoggant in the capri antifoggant undercoat can be, but need not be, reduced. For example, it is common practice to incorporate maximum concentration increasing antifoggants into processing solutions at concentrations ranging from about 5.times.10 to 317/l.

Even with the use of maximum concentration antifoggants at these concentration levels in the processing solutions used, benefits can be achieved by the presence of maximum concentration antifoggants in the antifoggant undercoat.

In addition to the maximum density increasing anti-capri agent, the anticapri agent undercoat includes a dispersion medium to drive the coating of the maximum density increasing antifoggant at the desired coverage. The dispersion medium can be selected from those commonly used in silver halide emulsions and other processing liquid permeable layers of photographic elements, as described in more detail below.

In addition to the antifoggant undercoat, the photographic elements of the invention further include one or more radiation-sensitive silver halide emulsion layers containing internal latent image-forming halodanized steel grains.

As used herein, the terms "halodanized steel particles forming an internal latent image" and "halodanized steel particles capable of forming an internal latent image" when coated, imagewise exposed, and developed in an internal developer; Used in the art-recognized sense to distinguish halodanized particles that produce substantially higher optical densities when equivalently coated, exposed, and developed in a surface developer. Preferred internal latent image-forming silver halide grains are coated onto a test area on a photographic support in accordance with standard photographic testing techniques (e.g., at a coverage of 3 to 4 g/m2) and have fixed times on the light-intensity scale. (e.g., 1×'10-2 to 1 second), e.g., 61cI
using a 500 watt tungsten lamp at a distance of n),
And Kodak's developer Deperot/Mana-DK-50 (
Kodak Developer Deperot Mother-DK-50 containing 0.5 g/'t potassium iodide when tested by developing for 5 minutes at 25°C in a surface developer).
(internal developer) is used instead of the surface developer,
Repeating this test should give a concentration that is at least 0.5 lower. The most preferred internal latent image-forming silver halide grains for use in the practice of the present invention, when tested using an internal developer and a surface developer as indicated above, when using an internal developer: It produces an optical density that is at least five times greater than that produced by a surface developer.

The internal latent image-forming halodanized steel particles, when coated as described above, exposed, and developed in a surface developer, exhibit a 0.0.
4, most preferably less than 0.25, i.e. the halodanized steel particles preferably initially exhibit substantially no fog and do not contain latent images on their surface. is even more preferable.

Kodak Developer Depero, a surface developer referred to herein as A-DK-50, is a surface developer from the Handbook of Physics and Chemistry (Handbook of Physics and Chemistry).
book of chemistry and phy
sicm).

30th edition, 1947, Chemical Rubber 79 Bridging Kanno =
Publishing Company), Relevbrand, Ohio, page 2558, and has the following composition: Water, approximately 52°C 500.0 cc N-Methyl-p-aminophenol 2.5 I! Sodium sulfite hemihydrate, dry 30.0 g Hydroquinone 2.5 g Sodium metaborate io, og Potassium bromide 0.5. ) i + Add water to form an internal latent image that can be used in the practice of this invention - silver rognide grains are well known in the art. Patents teaching the use of internal latent image-forming halogenated steel grains in photographic emulsions and elements include: U.S. Pat. No. 2,592,250;
6,313, 3.761,266, 3.5
No. 86,505, No. 3.772,030, No. 3,
No. 761,267, No. 3,761,276 and No. 4,035,185, the disclosures of which are incorporated herein by reference.

Preferred internal latent image-forming silver halide emulsions are core-shell emulsions. Such emulsions contain internal latent image grains that are internally sensitized. The interior, or core, of a sensitized silver halide grain is covered with an additional portion of silver halide called a shell. The main function of the shell is to prevent access of surface developer to the latent image sites located inside the shell due to internal chemical sensitization. As used herein, the term "core-shell" is intended to encompass any silver halide emulsion having these properties regardless of its method of preparation.

Useful core-shell emulsions can be prepared by first forming a sensitized core emulsion. The core emulsion can be comprised of grains of silver bromide, silver chloride, silver chlorobromide, silver chloroiodide, silver bromoiodide or silver chlorobromoiodide.

The grains can be coarse, medium sized, or fine, and can be bounded by (1oo), (111), (110) crystal faces or combinations thereof. The coefficient of variation of the core particle should not be greater than the desired coefficient of variation of the finished core-shell particle.

Perhaps the simplest ingenious approach to forming sensitized core particles is to incorporate a metal dotting agent inside the core particles as they are being formed. A metal doping agent can be placed in the reactor forming the core particles prior to the introduction of the silver salt. Alternatively, the metal doping agent may be used during the growth of silver halide grains at any stage of precipitation, with or without interrupting the introduction of silver and/or halide salts.
can be introduced.

Indium is specifically considered as a metal doping agent. It is preferably incorporated within the 710 silver dunide grains at a concentration of about 10-8 to 10-4 moles per mole of silver. Iridium is conveniently introduced into the reactor as a water-soluble salt, for example, an alkali metal salt of 710 g-iridium coordination complex salt,
For example, sodium or potassium hexachloride or hexachloride can be incorporated.

A specific example of iridium doping agent incorporation is provided by US Pat. No. 3,367,778.

Lead is also a specially considered metal doping agent for core particle sensitization. Lead is a common doping agent in emulsions (direct print and print out);
And similar concentration ranges can be used in the practice of this invention. The lead doping agent is at least 10 per mole of silver.
Preferably, it is present in a concentration of -4 molar. Up to about 5 X 10-2 moles per mole of silver, preferably about 2
Concentrations of up to X 10-2 molar are contemplated. Lead dopants, like iridium dopants, can be introduced in the form of water-soluble salts, such as lead acetate, nitrates, and lead cyanide. Lead dopants are exemplified by U.S. Pat. No. 3,287,136 and U.S. Pat. No. 3,531,291.

Another technique for sensitizing the core grains is to stop precipitation of the silver halide grains after the core grains are formed and chemically sensitize the surface of the cores.

Additional precipitation of silver halide then produces a shell surrounding the core. Particularly advantageous chemical sensitizers for this purpose are intermediate chalcodans, ie sulfur, selenium and/or tellurium sensitizers. Intermediate chalcodan sensitizers are preferably used at concentrations ranging from about 0.05 to 15 Da/silver mole. The preferred concentration is about 0.1 to lOmf! / silver mole. Further benefits can be realized through the combined use of gold sensitizers. The gold sensitizer is preferably used in a concentration range of 0.5 to 5 times that of the intermediate chalcodan sensitizer. Preferred concentrations of gold sensitizer typically range from about 0.01 to 40 Da/mole of silver, most preferably from about 0.1 to 20 rv/mole of silver. Adjusting contrast by adjusting the intermediate chalcodan to gold sensitizer ratio is described in the previously cited U.S. Pat. No. 4,035,
No. 185, this teaching is specifically incorporated herein by reference. US Pat. No. 3,761,276, cited above, describes specific examples of intermediate chalcogen core particle sensitizers.

It is preferred, but not essential, to chemically sensitize the core particle and then form a shell to complete the core-shell particle. It is merely necessary that the just-formed core-shell particles be able to form internal latent image sites. The internal sensitizing sites formed due to the shell formation of the sensitized core particles, i.e., the occlusion of foreign (i.e., other than silver and halogen) substances within the core-shell particles, are hereinafter referred to as internal sensitization sites. The physical sensitization site and the area are called internal chemical sensitization. By imparting irregularities in the crystal lattice of the core-shell particles, it is possible to incorporate internal physical sensitization sites. Such internal irregularities can be created by discontinuities in the silver halide precipitation or by rapid changes in the halide content of the core-shell grains. For example, it has been observed that precipitation of a silver bromide core followed by shell formation using more than 5 moles of silver bromide iodide does not require internal chemical sensitization to produce a direct positive. .

The sensitized core emulsion is described in the above-cited U.S. Patent No. 3.20.
Although the shell may be formed by the Ostwald ripening technique of No. 6,313, it is preferred that the silver halide forming the shell portion of the grain be precipitated directly onto the sensitized core grains by the Dapulget addition technique, published in December 1987. Item 1
7643.1, which is incorporated herein by reference, is well known in the art.

The halide content of the shell portion of the grains can be of any of the forms described above with reference to the core emulsion.

To improve developability, the shell portion of the particles preferably contains at least 80 moles St of chloride, with the remainder being bromide or bromide and 10 moles St.
It is iodide.

(Unless otherwise indicated, all halide percentages are based on the silver present in the corresponding emulsion, grain, or grain area under consideration.) An improvement in low-intensity reciprocity failure is also realized when For each of these advantages, silver cyclides are particularly preferred. On the other hand, it is generally accepted that the highest realized photographic speeds occur using primarily bromide particles, as taught in the above-cited US Pat. No. 3,761,276. Thus, the particular selection of preferred halides for the shell portion of the core-shell particles will depend on the particular photographic application. When the same halide is selected to form both the core and shell portions of the core-shell particle structure,
It is specifically contemplated to use double-jet precipitation to produce both the core and shell portions of the grains without interrupting the introduction of silver and halide salts during the core-to-shell formation transition.

The silver halide forming the shell portion of the core-shell grain must be sufficient to restrict developer access to the sensitized core portion of the grain. This will vary as a function of the developer's ability to dissolve the shell portion of the particles during development.

Although shell thicknesses as small as a few crystal lattice planes are taught in the art for developers with very low silver halide solubility, the shell portion of core-shell grains is , 206,313 and 4,035,185, in a molar ratio of about 1:4 to 8:1 with the core portion of the particle.

The amount of overexposure that can be tolerated by the emulsions of this invention without experiencing re-inversion can be increased by incorporating metal dopants into the core-shell grains for this purpose. As used herein, "reinversion" refers to the negative working characteristics exhibited by overexposed direct positive emulsions. (
Reversal is the opposite of solarization, which is a positive-working characteristic exhibited by overexposed negative-working emulsions. ) U.S. Patent No. 4
．． No. 395,478 (incorporated herein by reference):
The use of polyvalent metal ions as doping agents in the shell of core-shell emulsions to reduce inversion is disclosed. Preferred metal dopants for this purpose are divalent and trivalent cationic metal dopants, such as cadmium, zinc, lead and erbium. These dopants are generally less than about 5 X 10-' moles/mole of silver;
It is preferably effective at concentration levels below 5 x 1 O-5 moles/silver mole. at least 10 −6 mol/mol silver,
The doping agent should be present in the reactor during precipitation of the silver halide, preferably at a concentration of at least 5 x 10-' moles/mole of silver. Reinversion modified dosing agents are effective when introduced at any stage of silver halide precipitation. The reinversion modified doping agent can be incorporated into one or both of the core and shell. When the core-shell grains are high aspect ratio tabular grains, the doping agent is preferably introduced at the final stage of precipitation (eg, confined to the shell). Metal doping agents can be introduced into the reactor as water-soluble metal salts, such as divalent and trivalent metal halide salts. Doping agents of zinc, lead and cadmium to silver halide in similar concentrations, but to achieve other modifying effects, are disclosed in U.S. Pat.
No. 87,136, No. 2.950,970, No. 3,
No. 901,711 and No. 4,269,927. Other techniques for improving reinversion properties, described below, can be used alone or in combination with the metal dopants described.

After the shell portion is precipitated onto the sensitized core particles to complete the formation of the core-shell particles, the emulsion can be optionally washed to remove soluble salts. Common cleaning techniques, e.g. Research Disclosure cited above, y-(R@5earchDisclosure)
*Item 17643, as disclosed in Section 1 (incorporated here by reference), may be used. ' Since the core-shell emulsion is intended to form an internal latent image, deliberate sensitization of the surface of the core-shell grains is not essential. However, in order to achieve the highest attainable reversal speed, core-shell particles are
It is preferred to chemically sensitize the surface, as taught in No. 276 and No. 4.035,185.

Any type of surface chemical sensitization known to be useful in the case of corresponding surface latent image-forming silver halide emulsions, e.g.
can be used as disclosed in Sec.

Intermediate chalcogeno and /l or noble metal sensitizations, such as those described in the above-cited US Pat. No. 4.035.185, are preferred. Sulfur, selenium and gold are particularly preferred surface sensitizers.

Surface chemical sensitization increases the reversal sensitivity of the internal latent image-forming emulsion, but does not compete with internal sensitization sites to the extent that it shifts the location of the latent image center formed during exposure from the interior of the tabular grain to the surface. limited to a certain extent. Thus, a 74 lance between internal and surface sensitization is preferably maintained for maximum sensitivity, but internal sensitization accounts for the predominant proportion. Tolerable levels of surface chemical sensitization can be easily determined by relating surface development to internal development as described above.

In one particularly preferred form, the core-shell emulsion used in the practice of this invention is Reser Vol.
．． High aspect ratio tabular grain core-shell emulsions, as disclosed in January 1983, Item 22534 (incorporated herein by reference). When applied to emulsions, the term "high aspect ratio" wherein the core-shell particles have a thickness of less than 0.5 microns (preferably 0.3 microns) and a diameter of at least 0.6 microns and have an average aspect ratio of greater than 8:1 and core-shell silver halide. Defined as requiring the particles to occupy at least 50' of the total projected area.

As used herein, the term "aspect ratio" refers to the ratio of a grain's diameter to its thickness. It is defined as the diameter of a circle with equal area.

Research Disclosure Item 22 mentioned above
The core-shell tabular grains of 534 have an average aspect ratio of greater than 8:1, preferably greater than 10:1. Under optimal conditions of preparation, aspect ratios of 50:1 or even ioo:i are conceivable. As can be seen, the thinner the particle, the greater its aspect ratio for a given diameter. Typically, a particle of a given aspect ratio will have a diameter of 0.
It has a thickness of less than 5 microns, preferably less than 0.3 microns, optimally less than 0.2 microns. Typically the tabular grains have at least o,
It has an average thickness of os microns, but even thinner plate-like particles can in principle be used. In a preferred form of the invention, the tabular grains account for at least 70 inches, and optimally at least 90%, of the total projected surface area of the core-shell silver halide grains. The average diameter of the tabular grains is in all cases less than 30 microns, preferably less than 15 microns, and optimally less than 10 microns.

It is specifically contemplated that internal latent image-forming emulsions may be formulated to meet specific emulsion layer requirements. For example, it is possible to blend two or more emulsions with different average grain diameters. It is contemplated that internal latent image-forming particles of similar particle size distribution may be used in the formulation to minimize additive migration between different particle populations. When separate emulsions of similar particle size distribution are used in combination, their performance can be altered by differences in the level of surface sensitization, differences in terms of adsorbed nucleating agent, or differences in the proportion of internal sensitizer. , the latter being taught by U.S. Pat. No. 4,035,185.

In a particularly preferred form of the invention, the grains of the second emulsion are also core-shell grains. They can be identical to the core-shell grains of the first emulsion according to the considerations discussed above. In general, when the second core-shell grain population satisfies the relative size requirements of the two grain populations, another consideration is that the first and second grain populations have the same silver halide composition and are similar. You will also be satisfied when the inside is sensitized. Maintaining the second particle population substantially free of intentional surface chemical sensitization includes:
It is also advantageous in reducing the surface latent imaging ability of the second grain population within the direct positive exposure latitude of the formulated emulsion and increasing the reversal sensitivity of the formulated emulsion. No. 3,761,1, cited above, forming a first population of particles.
No. 76 and No. 4,035,185, a core-shell emulsion with surface chemical sensitization of the type disclosed in U.S. Pat. It is particularly preferred to blend with similar core-shell particles that exhibit no or reduced surface chemical sensitization.

The internal latent image forming emulsion can be spectrally sensitized if desired. For black and white imaging applications, spectral sensitization is not required, although ortho, cyclomatic or panchromatic sensitization is usually preferred.

Spectrally sensitizing dyes or combinations of dyes known to be useful in the case of negative-acting silver halide emulsions,
It can be used in the case of internal latent image forming emulsions. Examples of spectrally sensitizing dyes are disclosed in Research Disclosure, Item 17643.1V, cited above. Particularly preferred spectral sensitizing dyes are described in the Research Disclosure cited above.
e) + Item 15162 (incorporated herein by reference). Although the emulsions can be spectrally sensitized with dyes from various classes, preferred spectrally sensitizing dyes are polymethine dyes, such as cyanine, merocyanine, cyanine and merocyanine complexes (i.e. tri-, tetra-1 and poly-cyanine). and merocyanine), oxonol, hemioxonol, styryl, merostyryl, and strezotocyanine pigments. Particular preference is given to cyanine and merocyanine dyes. Spectral sensitizing dyes that sensitize surface fog direct positive emulsions generally desensitize both the negative working emulsion and the surface development of internal latent image forming emulsions and are therefore not considered for routine use in the practice of this invention. Spectral sensitization can be carried out at any stage of emulsion preparation known to be useful in the art. The most common spectral sensitization in this field is done after completion of chemical sensitization.

However, it is specifically recognized that spectral sensitization can alternatively be performed simultaneously with chemical sensitization, or can be performed completely prior to chemical sensitization of the surface. Sensitization is p
Modulation of Ag can be enhanced during chemical and/or spectral sensitization by, for example, cycling.

The preferential use of nucleating agents for uniform exposure in processing has been found to be advantageous. "Nucleating agent" [or "nucleating agent"] as used herein, in its art-recognized use, is used to image silver halide grains having an internal latent image formed by exposure of an imaging method prior to development. It refers to a fogging agent capable of allowing selective development of internal latent image-forming silver halide grains that have not been exposed to light.

The internal latent image-forming emulsion preferably contains a nucleating agent to facilitate the formation of a direct positive upon processing.

Although the nucleating agent can be incorporated into the emulsion during processing, it is preferably incorporated during manufacture of the photographic element, usually before coating.

This reduces the amount of nucleating agent required.

The amount of nucleating agent required can be reduced by limiting the movement of the nucleating agent within the photographic element. Large organic substituents that are capable of exerting at least some stabilizing (pallastizing) function are usually used.

Nucleating agents containing one or more groups to promote adsorption to the surface of silver halide grains have been found to be effective at very low concentrations.

A preferred general class of nucleating agents preferred for use in the practice of this invention are aromatic hydrazides.

Particularly preferred aromatic hydrazides are those in which the aromatic nucleus is substituted with one or more groups that restrict migration and preferably promote absorption of the 'hydrazide onto the silver halide surface. More specifically, preferred hydrazides are those disclosed in the following patents: U.S. Pat.
Same No. 4,080.207, Same No. 4,139,387, Same No. 4.276,364, Same No. 4,278,748
No. 4,478,928, and British Patent Application No. 2.011,391A and No. 2,012,4.
No. 43A. Still other useful hydrazines and hydrazines are disclosed in November 1983, Item 23510 (herein incorporated by reference).

A second preferred general class of nucleating agents preferred for use in the practice of this invention are N-substituted cycloammonium quaternary salts. Such nucleating agents are exemplified in the following patents: U.S. Pat. No. 3,759,901;
No. 3,615,615, No. 3,719,494, No. 3,734,738, No. 4,115,122
No. 4,471,044.

The particular choice of nucleating agent may be influenced by a variety of factors. U.S. Patent No. 4.030,92, cited above.
The nucleating agents of No. 5 and No. 4,276.364 are particularly preferred for many applications because they are effective at very low concentrations. A minimum concentration of nucleating agent as low as 0.1 IQ per silver mole, preferably at least 0.5171p, optimally at least IFn9, is disclosed.

These nucleating agents are particularly advantageous when reducing the loss of sensitivity and, in some cases, allowing increased processing temperatures to increase sensitivity.

Aromatic hydrazide nucleating agents are generally preferred for use in photographic elements intended to be processed at relatively high levels, typically 13 or higher. The alkynyl-substituted cycloammonium quaternary salt nucleating agent is p! (Particularly useful for processing 13 and below. U.S. Pat. No. 4,11
No. 5,122 teaches that these nucleating agents are useful in processing within the 10-13, preferably 11-12.50 tone range. In addition to the aforementioned nucleating agents, other identified examples of nucleating agents useful for processing at one level in the range of about 10-13 are as follows: U.S. Patent No. 4.036 N-substituted cycloammonium quaternary salt nucleating agents of the type disclosed in U.S. Pat. dihydrospiropyran biscondensation products of salicylic anhydride and at least one heterocyclic ammonium salt of the type described above; and diphenylmethane of the type disclosed in U.S. Pat. No. 4,315,986, incorporated herein by reference. Nucleating agent.

Instead of being incorporated into the photographic element during manufacture, the nucleating agent can be incorporated separately or additionally into the developer solution. Hydrazine (CH2N-NH2) is an effective nucleating agent that can be incorporated into the developer solution.

Instead of using hydrazine, any of a wide variety of water-soluble hydrazine derivatives can be added to the developer. Preferred hydrazine derivatives for use in developer solutions are disclosed in U.S. Pat.
No. 419,975 and.

No. 2,892,715. Preferred hydrazines for incorporation into the developer are described in US Pat. No. 4,269,929'.

Other preferred classes of nucleating agents that can be incorporated during development are those described in U.S. Pat.
, 224,401.

Once the internal latent image-forming emulsion has been produced by the precipitation procedure, washed, and sensitized as described above, its preparation is free from any incorporation of the aforementioned nucleating agents, and conventional photographic attachments. The procedure is complete and can be effectively applied to photographic applications requiring a silver image to be produced, such as ordinary black and white photography.

Internal latent image forming emulsions are comprised of a dispersion medium in which grains are dispersed. The emulsion layer and other layers including the anti-capri undercoat of the photographic element can contain a variety of colloids, alone or in combination, as vehicles, including binders and peptizers (-2 peptides). Preferred deflocculants are hydrophilic colloids, which can be used alone or in combination with hydrophobic substances.

Preferred peptizers are gelatin, such as alkali-treated gelatin (cow bone or skin gelatin) and acid-treated gelatin (pork skin gelatin), and gelatin derivatives, such as acetylated gelatin, phthalated gelatin, and the like.

Useful vehicles are those disclosed in the previous section (incorporated herein by reference). Layers of photographic elements containing crosslinkable colloids, particularly gelatin-containing layers, are described in Research Disclosure, cited above.
chDimclosurs) +Item 17643
In addition to the maximum density increasing antifoggants in the aforementioned undercoat, various organic and inorganic cures, as illustrated in Section Other known antifoggants and stabilizers can be incorporated at any useful position in the photographic elements of this invention. A variety of such additives are disclosed in Research Disclosure, Item 17643, cited above. Many of the antifoggants that are effective in emulsions can also be used during development and can be classified under several general headings, these include C, F, Mees,
, The Theory of Photographic Process
the Photographle Proee+ss
) 2nd edition, Macmillan, 1
954°677-680-14-di.

In addition to sensitizers, hardeners, and antifoggants and stabilizers, various other conventional photographic additives may be present. The particular choice of additives depends on the exact type of photographic application, and is well known in the art. Various useful additives are described in Research Disclosure #-', cited above.
ogure), disclosed in Item 17643 (incorporated herein by reference). Fluorescent brighteners can be introduced as disclosed in Item 17643, Section V. Absorbers and scattering agents can be used in the emulsions of this invention and in separate layers of photographic elements, as described in Section 1. Application aids, as described in Section X;
Plasticizers and lubricants may be present. Antistatic agents may be present, as described in Section X■. Methods for adding additives are described in Section X■. Matting agents can be incorporated as described in Section X■. One or more silver halide emulsion layers, antifoggant undercoats, and optional interlayers, overcoats, and subcoats (9 layers) present in the photographic element.
(when present) can be applied and dried as described in Item 17643, Section XV.

The layers of the photographic element can be coated on a variety of supports. Typical supports include I-rimer films, wood fibers, paper, metal sheets and foils, glass and ceramic support elements, which improve the adhesion, antistatic properties, and dimensions of the support surface. Suitable photographic supports include one or more subbing layers to enhance durability, abrasion, hardness, friction, antihalation and/or other properties. ).

The emulsion layer or layers are typically coated as a continuous layer onto a support having opposing planar surfaces, although this is not necessary. The emulsion layer can be coated as laterally displaced layer segments onto a flat support surface. It is preferred to use microporous supports when one or more emulsion layers are segmented. A useful microporous support is U.S. Pat. No. 4,387.14.
No. 6 (incorporated by reference).

The pores can have a width of 1 to 200 microns and a depth of up to 100,000 s microns. Generally, it is preferred that the pores have a width of at least 4 microns and a depth of less than 200 microns, with optimal dimensions being about Width and depth of 10-100 microns.

Photographic elements of the invention can be imaged by conventional means (
(Added here by citation) Ref. The invention is particularly advantageous when the imagewise exposure is carried out using electromagnetic radiation within the range of the spectrum in which the spectral sensitizer present exhibits an absorption maximum.

When the photographic element is intended for blue, green, red or infrared exposure, a spectral sensitizer is present that absorbs the blue, green, red or infrared portion of the spectrum. As mentioned above, for black and white imaging applications, it is preferred to orthochromatically or panchromatically sensitize the photographic element to extend the sensitivity of light within the visible spectrum. The radiant energy used for exposure can be incoherent (out of phase) or coherent (in phase) and can be generated by a lens. imagewise exposure at ambient, high or low temperature and/or pressure, e.g. exposure of high or low intensity, continuous or discontinuous exposure;
Exposure times ranging from a few minutes to relatively short periods in the millisecond to microsecond range are used with conventional sensitometry.
Technology, such as T, H, Jam Pass, (Mac
millan), 1977.4, 6.17.18 and 23.

The light-sensitive silver halide contained in the photographic element can be made available after exposure by processing to bring the silver halide into association with an aqueous alkaline medium in the presence of a developer contained in the medium or element. Can form visual images. Processing recipes and techniques are described in the following literature: L. F. Mason, The Chemistry of Photographic Processing.
phic Procsssing Chemistry
), Focal Prel+s
), London, Stomann Koda, Ri Company, 1
973;7 Morgan and Morgan Incorporated
c, ), Doffs Ferrer
y), New York (New Pants Strand Reinhold Kanno Mother's knee (vanNostrand R)
e1nhold Company), 7th edition, 19
77° Processing methods include: web processing;
Illustrated by U.S. Pat. No. 3,179,517; stabilization treatment, U.S. Pat. No. 3,220,839;
615,511 and 3,647.453 and British Patent No. 1,258.906;
Morgan Incorporated
dMorgan + Inc, ), 1966, U.S. Patent No. 3,240,603, U.S. Patent No. 3.615.513, U.S. Patent No. 3.628.955, U.S. Patent No. 3,723,126
Contagious Development, U.S. Patent No. 3.294;
．． No. 537, No. 3.600, 174, No. 3.61
5.519, 3.615,524, 3.5
No. 16,830, No. 3.615゜488, No. 3.
625.689, 3,632,340 and 3.708,303, and British Patent No. 1,273.
．． No. 030; Dural Development, U.S. Pat.
．． 232,761; roller transfer process, U.S. Pat. No. 3.025,779;
, No. 556, No. 3,573.914 and No. 3.
647,459 and British Patent No. 1.269,26
No. 8 Illustrative Sensing Index (Produ
ctLlcensingIndex), vol.
97. May 1972, Item 9711, illustrated by U.S. Pat. Nos. 3,816.136 and 3.985.564;
5.283-287, October 1976, Item 15034; Surface Application Treatment, illustrated by U.S. Pat. No. 3,418,132.

Development is preferably carried out in the presence of a nucleating agent as described above, but once the photographic element has been provided, an overall exposure is alternatively carried out immediately before or preferably during development. be able to. When using an overall flood-exposure, it can be high intensity and short time, or low intensity and long time.

The silver oxide developer used in the present invention is a surface developer. The term "surface developer" refers to the appearance of surface latent image centers on 5-silver grains, but the surface photosensitive
Includes developers that do not cause substantial internal latent image centers to appear in internal latent image-forming emulsions under conditions commonly used for developing silver rognide emulsions. The surface developer generally utilizes any silver monide developing agent or reducing agent, but the development bath or composition is a silver monoxide solvent (silver monide) that disrupts or dissolves the grains to reveal a substantial internal latent image. For example, they are generally substantially free of water-soluble thiocyanates, water-soluble thioethers, thiosulfates, and ammonia).

Although small amounts of excess halide are sometimes desirable in the developer or incorporated as K-logonide releasing compounds in the emulsion, larger amounts of iodide or iodide releasing compounds generally prevent substantial grain collapse. to be avoided.

Typical silver gonide developers that can be used in the developing compositions of the present invention include hydroquinone, catechols, aminophenonyls, 3-pyrazolidinones, ascorbic acid and its derivatives, reactones, and phenylenediamines. , or a combination thereof. A developer can be incorporated into a photographic element, where the developer is contacted with silver rhodanide after exposure in an imaging process; however, in some embodiments, the developer is preferably in a developer bath. used in

Once a silver image is formed in a photographic element, fixing of the undeveloped silver halide is commonly performed.

High aspect ratio platelet grain emulsions are particularly advantageous in that fixing can be completed in a short time. Unless otherwise specified, the remaining surfaces of the black-and-white direct positive photographic elements of the present invention and the processing of these photographic elements after image exposure to produce a direct positive are suitable for such photographic applications. It should be understood that this encompasses aspects that are recognized in this field.

Margin below 〔Example〕 The invention is further illustrated by the following specific examples.

Example 1 (1), Coating Layer A, Control Coating Layer A 0.8 μm octahedral core-shell AgBr emulsion was prepared by the Dapulge precipitation technique. The core particles are 0.
78mg Na 2s 203 ・5 H20/MokA
g and 1.18 calls of KA u C14 8 in 1 mole Ag
0.55 μm chemically sensitized for 30 min at 5°C
It consisted of octahedral AgBr. The core-shell emulsion was chemically sensitized with 1.0 mg of Na2S2O3,5H20 1 mole Ag at 74 DEG C. for 30 minutes. 7.02. This emulsion was deposited on a polyester film support. ! 7/m2
of silver and 4.86.97 m2 of gelatin.

The emulsion layer also contains the spectral sensitizing dye anhydro-5,5'
-dimethoxy-3,3'-bis(3-sulfopropyl)
Selenacyanine hydroxide, sodium salt (dye A)
and anhydro'-5,5'-dichloro-3,9-
Diethyl-3'-(3-sulfopropyl)oxacardocyanine hydroxide (dye B) *Each &200 1
mole Ag and the nucleating agent 6-nitylthiocarpamate 2-methyl-1-7'roA? It contained lugyl quinaridinium trifluoromethanesulfonate at 30 kg and 1 mol Ag. The element was overcoated at 1.08 I/m with gelatin containing 1.7% by weight bis(vinylsulfonylmethyl)ether based on total glue content pressure.

B. Example Coating Layer The control coating layer was again formed using a 1.8 x 10" anti-capri agent undercoat between the emulsion layer and the support.
-2 moles/silver mole of AF-5 and gelatin (1,29
#/rn) was used.

■, Processing A, control coating layer The exposed portion of the control coating layer is treated with a developer (Developer, yt!)
■ The developer was processed for 75 seconds at 38°C in
．． 10.9/l AF-5 and 0.16F/l 1-
Phenyl-5-mercazototetrazole (hereinafter referred to as PMT)
) was further included.

B. Coating layer of the example The exposed portion of the coating layer of the example was processed for 75 seconds at 38°C in developer ①, which had an AF of 0.151/l.
-5 and 0.1111/l of PMT.

■, Sensitometry The results of sensitometry are shown in Figure 2 and Table ■.

Table ■ Control (C-1) 236 6.3 4.4 7.02
0.11 Example (E-1) 273 8.9 6.2
6,89 0. Of*sensitivity is taken at 0 to 3,0 density steps step tablet (0,15 density steps) plus 0.2 density + D-m1n for a 10-5 second exposure through a 0.86 neutral density filter, and 465 A filter was used to simulate the emission of a phosphor with a wavelength maximum of nm.

As the results show, the effect of AF-5 in the undercoat improves sensitivity, contrast and D(
(maximum concentration) and decrease max D-min (minimum concentration). The developed Ag coverage was greater for the present invention since higher D-□,X was obtained at lower developed Ag. The example coating also exhibits greater separation between the positive and reversal negative than in the control coating, as can be seen in FIG.

■Quality of 0 image The coating layer part is the same as above, but there is a small image instead of a gradual tablature.
t@rget ), and an inference of image quality was drawn. FIG. 3A shows the results of exposing a control coating at an exposure equivalent to step A7 (FIG. 2) and a coating of the invention at step A9 (light micrographs are at 100X magnification).

The corresponding optical micrographs at 400X are shown in Figures 4A and 4B. These results show that the coatings of the present invention exhibit improved image quality and more finely dispersed filamentary silver than the control.

Electron microscopic cross-sections of exposed and treated coatings taken from a density step of about 0.4 are shown in Figures 5A and 5B at 22.000X magnification, respectively, for the control coating and the coating of the invention. Show about layers.

These results demonstrate a more uniform distribution of developed silver through the emulsion layer (2a and 2b) and the presence of more finely dispersed filamentary silver in the inventive coatings compared to the control coatings. However, these coated layers showed a concentration of developed silver near the support (la and lb) surface.

Developer I Component 11/Tap water 850.0 Ethylene diamino tetraacetic acid 1.0 KOT (,45% 22.0 Anhydrous Na280.75.0 NaBr 8.0 2-ethylaminoethanol 58.63.3'-diamino Dipropylamine 4.0 Hydroquinone 40.
Example 2 ■, Coating Layers Control and Example coating layers were prepared essentially the same as those of Example 1, except that 1% by weight of formaldehyde was added to bis(vinylsulfonylmethyl). ) to cure the overcoat in place of the ether curing agent and 1-(4-(2-formylhydrazino)phenyl]-3-hexylurea (276 mq/Ag
mole) and 1-formyl-2-(4-[2-(2,4
-G-tart-<methylphenoxy)butyramide]
phenyl)hydrazine (78~/Ag mol) was used.

(2) The coated layers of the processing control and examples were exposed, and the developer (2) Shirasu 0.01/l of Ay-s + o, os, p/l of PM
Developed in T at 38°C for 104 seconds.

■, Sensitometry The results of sensitometry are shown in Figure 6 and Table ■.

Table ■ Control (C-2) 257 9.9 3.24 0.09
Example (F-2) 286 6.7 3.35 0.0
4*Sensitivity is as described in Example 1.

As shown by the results in Table 1 and Figure 6, the effects of AF-5 in the K and undercoat are significant in terms of sensitivity and D as compared to the control.
, decrease D-min, and increase the sensitivity separation between the positive and negative responses.

■Quality of one image An optical microscope taken using the same method as in Example 1,
Similar improvements in image quality were shown for the Examples compared to the Control.

Developer ■ Tap water 850.0 Ethylene diamino tetraacetic acid 1.0 KOH, 45% 22.0 Anhydrous Na25o360.0 4.4'-dimethyl-1-phenyl-3-pyrazolidinone 0.6 NaBr 3.0 2-ethyl Aminoethanol 58.63.3'-Zaminodiprobylamine 4.0 Add tap water and add 1 to Example 3 ■, Coating layer A, control coating layer (C-2) The control coating layer of Example 2 again Prepared.

B, Control Coating (C-3) This control coating was similar to Control Coating C-2, but with 0.
691/m2 of silver and further contains 1.76
It contained 5.

Coating layer of Example C1 (E-3) This coating layer is similar to coating layer E-2 of Example 2, but with 0
．． 67, iil/m2 silver and 1.85 X 10-2 moles/silver mole AF in the undercoat
-5. The silver coverage and concentration of AF-5 in coated layers C-3 and g-3 are substantially the same, with the only material difference between these coated layers being that AF-5 is higher than coated layer C-3.
It was present in the silver halide emulsion layer in No. 3, and in the undercoat in coating layer E-2.

Margin ① below, Processing All coated layers were exposed to light and processed in developer ② for 75 seconds (38°C).

■, Sensitometry The results of sensitometry are shown in Figure 7 and Table ■.

Table ■ Control (C-2) 257 3.8 4.1 0.06 Control (C-3) 247 2.5 4.5 0.10 Example (E-3) 282 5-0 40 0.03* Sensitivity is as described in Example 1.

As shown in Table 1 and the results in FIG. 7, the coating layer E-3 of the example containing KAF-5 in the undercoat was
Higher sensitivity, higher contrast, lower minimum density (D,) compared to control coating layer C-2 not containing AF-5 and control coating layer containing AF-5 in the silver monologonide emulsion layer. , resulting in increased exposure separation of InIn and re-inverted images. The location of the maximum concentration-enhancing anticapri agent in the undercoat produced these differences in performance.

Developer/agent ■ Tap water 850.0 Ethylene diamino tetraacetic acid 1.0 KO) I, 45% 22.0 AF-50.05 1-phenyl-5-mercazotterazole 0.08 Anhydrous Na25o, 60.0 NaBr 3.0 2-ethylaminoethanol 58.63.3'-Zaminodiprobylamine 4.0 Hydroquinone 40
．． 0 Add tap water 1t EFFECTS OF THE INVENTION Several highly useful advantages have been observed in the visible silver imaging direct positive photographic elements and methods of the present invention. An increase in photographic sensitivity was observed. In some cases, a desirable increase in contrast was also achieved. An extended overexposure limit before facing reinversion was observed. Furthermore, both a desirable reduction in minimum density and a desirable increase in covering power were achieved. Microscopic examination of the produced silver images revealed an improvement in image quality due to the finer, more evenly distributed silver filaments produced by the process.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 shows the formalized characteristic curve of a direct positive emulsion, Fig. 2, Fig. 6, and Fig. 7 show the density v of the emulsion, respectively.
s, exposure characteristic curves, and Figures 3A, 3B, 4A, 4B, 5A, and 5B, respectively, showing the grain state of the silver filaments in the coating of the imaged element. This is a microscopic photograph. Patent Applicant: Eastman Kodak Company, Patent Attorney: Akira Aoki, Patent Attorney: Kazuyuki Nishidate, Patent Attorney: 1) Yukio, Patent Attorney: Akira Yamaguchi, Patent Attorney: Masaya Nishiyama Amount of exposure FIG, 1 Amount of exposure FIG, 2

Claims (1)

[Claims] 1. A visible silver image comprising a support, one or more radiation-sensitive emulsion layers containing internal latent image-forming silver halide grains, and a maximum density increasing anti-capri agent. A black-and-white direct-positive photographic element for forming a black-and-white direct-positive photographic element, wherein said maximum density-enhancing anticapri agent is located in an undercoat between said emulsion layer and said support.