JPH0862760A - High contrast photograph element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved high-contrast black and white photographic element which is doped by a method, for effectively providing low-speed and high-contrast without the drastic loss in the max. density and may be handled under interior light. SOLUTION: The high-contrast black and white photographic element, which is adapted particularly for the field of graphic arts and may be handled under the interior light, contains high-chloride silver halide particulates doped with a dopant, consisting of a nitrosyl or thionitrosyl ligand and a transition metal. The dopant exists in the grains in the amt. sufficient to lower the speed and intersifying the contrast in the element. At least 25wt.% in the total amt. of the dopant in the grains exits within a range of 90% from the outer side of the total grain volume. The solarization effect and intermittent exposure effect of the emulsion are lowered, by which the max. density of the element is increased.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to photography, and more particularly to novel black and white silver halide photographic elements. More particularly, the present invention relates to hard-silver halide photographic elements handleable under room light that are particularly useful in the field of graphic arts.

[0002]

BACKGROUND OF THE INVENTION High-contrast silver halide photographic elements that can be handled in room light are well known and widely used in graphic arts applications. The term "handleable under room light" indicates that the material can be exposed to light levels of 200 lux for several minutes without significant loss of photographic behavior. The silver halide emulsions utilized in hard photographic elements that can be handled under room light have the desired low sensitivity, typically by using a small grain size, and suitable doping to control photographic speed. It is a low-sensitivity emulsion achieved by doping silver halide grains with an agent. It is also a conventional technique to incorporate filter dyes in the overcoat layers of photographic elements to absorb unwanted light and reduce photographic speed.

Radiation-sensitive silver halide fine particles having a face-centered cubic crystal lattice structure, containing a nitrosyl or thionitrosyl ligand and a transition metal selected from Groups 5 to 10 of the Periodic Table of Elements therein. The photographic silver halide emulsions contained therein are described in McDugle et al., US Pat.
4,933,272. U.S. Pat.No. 4,93
As described in 3,272, these doping agents are useful in a wide variety of photographic elements and are particularly useful in high contrast black and white photographic elements that can be handled under room light.
In such elements, these doping agents are used in relatively high concentrations for the purposes of speed reduction and contrast enhancement. However, such high concentrations tend to cause solarization and intermittent exposure problems, with consequent loss of maximum density.

[0004]

PROBLEM TO BE SOLVED: To provide a high contrast black and white photographic element handleable under improved room light which is doped in a manner which effectively provides low speed and high contrast without significant loss of maximum density. The present invention is directed to the purpose.

[0005]

In accordance with the present invention, a room-light-handleable high-contrast black-and-white silver halide photographic element specially adapted for the field of graphic arts comprises nitrosyl or thionitrosyl ligands and elements. A silver halide emulsion layer containing highly chloride radiation-sensitive silver halide fine particles having a face-centered cubic crystal lattice structure, containing a dopant made of a transition metal selected from Groups 5 to 10 of the periodic table A support that supports the dopant, the dopant being present in the particles in an amount sufficient to reduce the speed of the element and enhance contrast, with at least 25 weight percent of the total amount of the dopants in the particles. Within the range of 90 percent from the outside of the total grain volume to reduce the solarization and intermittent exposure effects of the emulsion, thereby Increase the maximum concentration of the element.

It is preferred that at least 50 weight percent of the total amount of the dopants in the grains be within the outer 90 percent of the total grain volume. In the most preferred embodiment of the invention, 100 weight percent of the total amount of said dopants in said particles is within the range of 90 percent from the outside of the total grain volume. Solarization is a well known problem in the photographic art. It refers to the phenomenon that the developable density decreases when the silver halide emulsion is significantly overexposed. The main cause of solarization is the destruction of the surface latent image by the halogen liberated by the formation of the internal latent image. The intermittent exposure effect is also a well-known problem in the photographic art. It refers to a phenomenon in which, with the same energy, the effect obtained by intermittent exposure is lower than the effect obtained by continuous exposure. The characteristic curves obtained with intermittent exposure have lower densities, especially at lower intermittent exposure effect values.

More detailed information relating to both solarization and intermittent exposure effects can be obtained from standard textbooks relating to photography [eg photographic materials and processing.
(Photographic Materials And Processes ), Leslie S
troebel, John Compton, Ira Current and Richard Z
akia, Butterworth Publishers, 80 Montvale Avenue, S
toneham, MA 02180, 1986, James, The theory of photo processing (The
Theory of the Potographic Process, 4th Ed., MacMi
llan Publishing Co., 1977, and Introduction to Photo Theory (Int
roduction to Photographic Theory) , BH Carroll,
GC Higgins and TH James, John Wiley & Sons,
See New York, NY 1980). Utilizing the doping agent of U.S. Pat.No. 4,933,272 such that at least 25 weight percent of the total amount of dopant in the grain is within the range of 90 percent from the outside of the total grain volume in accordance with the present invention, solarization and intermittent It has been found to eliminate, or at least sufficiently reduce, the problem of exposure effects, thereby eliminating or at least sufficiently reducing the loss of maximum density resulting therefrom. During the precipitation process of silver halide grains, the dopant typically has a dopant band (ban) within the grain.
It is incorporated into the silver halide in the method of forming d), and the width and arrangement of this band can be easily manipulated so that the dopant is present according to the desired purpose in said method. For example, the time at which the dopant incorporation is initiated during the precipitation process and the operating period during which the dopant is incorporated can be selected to achieve this end. The optimal width of the band, the optimal distance from the center of the grain to the inner edge of the band and the optimal distance from the outer edge of the band to the surface of the grain are: grain size, halide content, the specific dopant used and the concentration of the dopant. Will vary depending on factors such as.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Typically, high contrast black and white photographic elements handleable under room light utilize high chloride fine grain emulsions. Therefore, the particles utilized in the present invention are less than 0.4 micrometer, preferably less than 0.2 micrometer,
And most preferably it has an average particle size of less than 0.1 micrometer. It is also preferred that the particles utilized in the present invention have a chloride content of at least 80 mol%, and preferably at least 90 mol%. Most preferably, the particles are 100 percent chloride. The high room light handleable photographic elements of this invention utilize the dopant agents of US Pat. No. 4,933,272, ie, dopants containing nitrosyl or thionitrosyl ligands. As shown in the examples herein, the presence of dopants such that at least 25 weight percent of the total amount of dopant in the grain is within 90 percent from the outside of the total grain volume results in solarization and intermittency. Eliminate or substantially reduce exposure effects. This provides a very desirable combination of low speed, high contrast and high maximum density (D _max ) _handleable elements under room light.

The hard-light photographic elements that can be handled under room light of the present invention can utilize any of the polymeric film supports known for their use in the photographic art. Typical useful polymeric film supports are cellulose nitrates and cellulose esters such as cellulose triacetate and cellulose diacetate, polystyrenes, polyamides, vinyl chloride homopolymers and copolymers, poly (vinyl acetals), polycarbonates, Homopolymers and copolymers of olefins such as polyethylene and polypropylene, and polyesters of dibasic aromatic carboxylic acids and dihydric alcohols such as poly (ethylene terephthalate) films. Polyester films, such as films of polyethylene terephthalate, have many advantageous properties, such as excellent strength and dimensional stability, which make them particularly advantageous for use as supports in the present invention.

Polyester which can be advantageously used in the present invention
Film supports are well known and widely used materials. Such film supports are typically
It is prepared from high molecular weight polyesters or their derivatives derived by condensing dihydric alcohols with dibasic saturated aliphatic carboxylic acids. Suitable dihydric alcohols suitable for use in preparing the polyester are well known in the art and include any glycol having a hydroxyl group on the terminal carbon atom and containing from 2 to 12 carbon atoms. , Ethylene glycol, propylene glycol, trimethylene glycol, hexamethylene glycol, decamethylene glycol, dodecamethylene glycol, and 1,4-cyclohexanedimethanol. Dibasic acids that can be used in preparing polyesters are well known in the art and include those dibasic acids containing from 2 to 12 carbon atoms. Specific examples of suitable dibasic acids include adipic acid, sebacic acid, isophthalic acid and terephthalic acid. Further, alkyl esters of the above acids can also be used sufficiently. Another suitable dihydric alcohol and dibasic acid that can be used in preparing the polyesters that can be prepared into sheets is published on October 11, 1955, J.
W. Wellman, U.S. Pat. No. 2,720,503.

Particularly preferred specific examples of the polyester resin which can be used in the present invention when forming a sheet are poly (ethylene terephthalate) and poly (cyclohexane 1, 1.
4-dimethylene terephthalate) and 0.83 mol of dimethyl terephthalate, 0.17 mol of dimethyl isophthalate and at least 1 mol of 1,4-cyclohexanedimethanol. U.S. Pat.No. 2,901,466 describes 1,
Disclosed are polyesters prepared from 4-cyclohexanedimethanol and methods for making them. The thickness of the polyester sheet material used to practice the invention is not critical. For example, about 0.05 to about 0.25
Satisfactory results are obtained using a millimeter thick polyester sheet.

In a typical process for making polyester photographic film supports, polyester is melt extruded through a slit die, quenched into an amorphous state, stretched by stretching in the transverse and longitudinal directions, and heated under dimensional constraints. set. In addition to directional stretching and heat setting, the polyester film can be subsequently subjected to a heat relaxation treatment to further improve dimensional stability and surface smoothness. The photographic elements of this invention are high contrast materials of specific contrast value, as indicated by gamma (γ), depending on the type of emulsion used. Gamma is, for example, James, photo processing
The Theory of the Photographic Process
4th Ed., 502, MacMillan Publishing Co., 1977, a measure of contrast well known in the art.

In addition to the high chloride silver halide fine grain emulsion layer, the elements of the invention include additional layers disposed between the emulsion layer and the overcoat layer, such as a backing layer, a protective overcoat layer and an intermediate layer. Layers can be optionally included. As noted above, fine grain emulsions having an average grain size of preferably less than 0.4 micrometers are utilized in the present invention. The method for measuring the average grain size of silver halide grains is
It is well known in the photographic art. They are, for example, James,
The Theory of the Photographic Pro
cess) 4th Ed., pages 100-102 , MacMillan Publishi
ng Co. (1977).

The silver halide emulsion used in the present invention is
Doping agents such as those described in U.S. Pat. No. 4,933,272 use incorporated silver halide grains to control speed. Also, such doping agents enhance the contrast. Doping agents are typically added during the crystal growth stage of emulsion preparation, eg, during the initial stages of precipitation and / or during physical ripening of silver halide grains. McDugle, published June 12, 1990
Other U.S. Pat. No. 4,933,272, the disclosures of which are incorporated herein by reference, select nitrosyl or thionitrosyl ligands and groups 5 to 10 of the Periodic Table of the Elements. Disclosed is a silver halide emulsion containing a radiation-sensitive silver halide grain having a face-centered cubic crystal lattice structure, which internally contains a transition metal dopant. These emulsions are adapted for use in the room-light-handleable high contrast photographic elements of the present invention by controlling the presence of dopants as described above.

According to the above-mentioned US Pat. No. 4,933,272, the dopant contained in the silver halide grains is 1
It is a transition metal coordination complex containing one or more nitrosyl or thionitrosyl ligands. These ligands have the formula

Embedded image Where Y is oxygen for nitrosyl ligands and sulfur for thionitrosyl ligands.

In the aforementioned US Pat. No. 4,933,272 and all references therein, the periods and groups within the Periodic Table of the Elements are defined by the American Chemical Society.
) And Chemical and Engineering Ne
ws, based on the format of the Periodic Table published on page 26, February 4, 1985. In this form, we retained the previous numbering for cycles, but the Roman numerals for the tribes and the A and B symbols (which had the opposite meaning in the US and Europe) were simply for the tribes. Replaced with a serial number from 1 to 18 from left to right. A preferable transition metal coordination complex satisfying the requirements of the invention is represented by the following formula [ML ₄ (NY) L ′] ⁿ (wherein M is a transition selected from Groups 5 to 10 of the periodic table of elements). A metal, L is a binding ligand,
L'is L or (NY), Y is oxygen or sulfur, and n is zero, -1, -2 or -3) and is a hexadentate complex.

According to the invention, the radiation-sensitive particles of cubic crystal lattice structure contain at least one nitrosyl or thionitrosyl ligand in order to modify the photographic behavior, a transition metal coordination complex, preferably a hexadentate. A photographic emulsion containing a coordinated transition metal complex is conceivable. The remaining ligands can be any convenient bridging ligand, including additional nitrosyl or thionitrosyl bridging ligands. Specific examples of preferred bridging ligands other than nitrosyl and thionitrosyl ligands include aco ligands, halide ligands (especially fluoride, chloride, bromide and iodide), cyanide ligands, cyanate ligands. Order,
Includes thiocyanate, selenocyanate, tellurocyanate and azide ligands. Further bridging ligand selections are possible. Preferably, the nitrosyl or thionitrosyl ligand occupies one or two or all ligands, and when an aco ligand is present it occupies only one or two ligands. It is preferable. Hexadentate transition metal complexes containing up to 5 halide and / or cyanide ligands in addition to the nitrosyl and thionitrosyl ligands are particularly preferred.

The present invention can be practiced with any transition metal capable of forming a coordination complex. It is known that transition metals from groups 5 to 10 of the periodic table form tetradentate and hexadentate complexes. Preferred transition metals from groups 5 to 7 are light (4th period) transition metals, while in groups 8 to 10 the trivalent elements of the heavy transition metals platinum and palladium are preferred. . Often, transition metal coordination complexes that are believed to be incorporated into the particles exhibit a net ionic charge. Thus, usually one or more counterions associate with the complex to form a charged neutral compound. The counterion is less important because the complex and its counterion or ions dissociate and are introduced into the aqueous medium, such as those used to form silver halide grains. Ammonium and alkali metal counterions are anionic hexadentate complexes that meet the requirements of the invention, as these cations are known to be fully compatible with silver halide precipitation methods.

Particularly preferred hexadentate coordination complexes for use in the present invention are of the formula: [M ¹ (NO) L ¹ ) ₅ ] ^{m In the} above formula, m is zero, -1, -2 or -3,
M ¹ is chromium, rhenium, ruthenium, osmium or iridium, and L ¹ is one or a combination of halide and cyanide ligands or up to two aco ligands and these ligands. Represents a combination.

In the present invention, the concentration of dopant used is sufficient to provide a nearly desirable speed reduction. Typically, the concentration is about 1 × 10 6 per mole of silver.
^-6 to about 2 x 10 ^-3 mol, and preferably about 5 x 10 ^-6 to about 3 x 10 ^-4 mol per mol silver. In practicing the present invention, the various dopant bands can be modified by adjusting the duration of the intervals during which the dopant is added during the precipitation process of the silver halide grains, so that the width of the bands will change directly during this interval. Can be easily adjusted. Also, the placement of the dopant bands can be easily adjusted by selecting the time at which the dopant addition begins. By delaying the onset of dopant addition for a suitable time during precipitation, the dopant band can be located near the surface of the silver halide grain. For example, a silver halide grain precipitation method that requires a total completion time of 15 minutes is possible. When the addition of the dopant is started 3 minutes after starting the precipitation,
Dopant bands will be located closer to the grain surface than after minutes. Addition of the dopant for 3 minutes, rather than a total time of 1 minute, will give a band wide enough. According to the present invention, the placement of the dopant within the grain is adjusted to eliminate or at least reduce solarization and intermittent exposure effects.

In the present invention, the placement of the dopant is adjusted in relation to the grain volume. This has to be taken into account when choosing the rate at which the dopant is added, the time at which the dopant is started and the period during which the dopant is added, as the particle volume changes approximately proportionally to the cubic particle size. is there. In growing silver halide grains, the average grain size doubles much faster at the beginning of processing than at their later stages. When the silver halide grains are very small, the average grain size increases rapidly as a result of the addition of a given amount of halide salt and silver salt,
However, when the grains are large, the addition of this same amount of halide salt and silver salt does not significantly change the grain size. Thus, the dopant addition can actually begin early in the grain growth process and the dopant bands are located away from the core region of the grain.

In addition to the doped silver halide grains, the silver halide emulsion used in the present invention contains a hydrophilic colloid supplied as a binder or vehicle. The proportion of hydrophilic colloid can be varied, but is typically in the range of about 20 to 250 g / mole silver halide. The presence of excess levels of hydrophilic colloids can reduce the maximum image density and consequently the contrast. Therefore, for gamma values of 10 and above, the vehicle is preferably present at a level of 200 g / mole silver halide. The hydrophilic colloid is preferably gelatin, but a number of other suitable hydrophilic colloids are known in the photographic art and can be used alone or in combination with gelatin. Suitable hydrophilic colloids include natural products such as proteins, protein derivatives, cellulose derivatives, eg cellulose esters, gelatine, eg alkali-treated gelatin (cattle bone or hide gelatin) or acid-treated gelatin (pigskin). Gelatin), gelatin derivatives--for example, acetylated gelatin, phthalated gelatin and the like, polysaccharides such as dextran, acacia, zein, casein, pectin, collagen derivatives,
Includes collodion, agar, arrowroot, albumin, etc.

As previously described herein, the silver halide grains utilized herein are high silver chloride grains that typically have a chloride content of at least 80 mole percent.
The remaining halide is typically bromide, but can include minor amounts of iodide. In addition to hydrophilic colloids and silver halide grains, the radiation-sensitive silver halide emulsion layers used in this invention can contain polymer latices that help improve the dimensional stability of the film. The polymers used to form the latex for this purpose are well known in the photographic art. The requirement for such a polymer latex is (1) not to interact with hydrophilic colloids which would not allow the usual coating of emulsion layers,
(2) Optical properties, that is, having a refractive index similar to that of hydrophilic colloid, and (3) having a glass transition temperature that is plastic at room temperature. The glass transition temperature is preferably 20 ° C or lower.

The polymer latex useful in the present invention is an aqueous dispersion of a water insoluble polymer. It is typically incorporated into the emulsion layer in an amount ranging from about 0.2 to about 1.5 parts per part by weight of hydrophilic colloid. Synthetic polymer latex materials, as referred to herein, are generally relatively insoluble in water compared to water-soluble polymers, but sufficiently water-soluble to produce colloidal suspensions of small polymeric micelles. Is a polymeric material having Typical latex polymeric materials can be produced by rapid copolymerization with vigorous stirring in an aqueous carrier of at least one monomer that will produce a hydrophobic homopolymer. In some preferred embodiments, about 1 to about 30 weight percent of the units of monomer containing water solubilizing groups are present in the copolymer product. The copolymers prepared by this method and similar methods provide discrete micelles of the copolymer having low viscosity in aqueous suspension. Typically useful copolymers are
Dykstra, U.S. Pat. No. 3,411,911, November 1968 19
Acrylic ester and sulfoester copolymers disclosed in Japanese, Dykstra and Whiteley, U.S. Pat. No. 3,411,912, issued Nov. 19, 1968. , Ream and Fowler, U.S. Pat. No. 3,287,289, copolymers of alkyl acrylates and acrylic acid disclosed in Nov. 22, 1966, Corey, U.S. Pat.
Copolymers of vinyl acetate, alkyl acrylates and acrylic acid disclosed in 3,296,169, and Sm
ith, U.S. Pat. No. 3,459,790, including copolymers disclosed in August 5, 1969. Polymer latex materials can also be produced by rapid polymerization of hydrophobic polymers with vigorous stirring when polymerized in the presence of surfactants containing high concentrations of water solubilizing groups. The surfactant is clearly incorporated into the micelles, and the solubilizing groups of the surfactant provide sufficient compatibility with the aqueous solution to provide a dispersion very much like soap. Generally good latex materials have been reported by Nottorf, US Pat. No. 3,142,568, issued July 28, 1964, White, US Pat. No. 3,193,386.
No., issued July 6, 1965, Houck et al., US Patent No.
No. 3,062,674, issued November 6, 1962, and Houc
k et al., U.S. Pat. No. 3,220,844, issued Nov. 30, 1965.

The synthetic polymer latex material is generally polymerized to produce micelles of average diameter less than about 1.0 micron, which is very useful in photographic emulsions, and preferably the discrete micelles have an average diameter of less than 0.3 microns. Is.
In general, micelles can be observed micrographs when incorporated into gelatin emulsions, however, it is speculated that some coalescence will occur as the emulsions are coated and dried. In some embodiments, the latex polymers that can be used in accordance with the present invention are acrylic copolymers, ie, those copolymers prepared from polymerizable acrylic monomers containing characteristic acrylic acid groups.

[0026]

Embedded image

Such polymers are conveniently prepared by copolymerization of acrylic monomers with at least one different monomer which may be another acrylic monomer or another different polymerizable ethylenically unsaturated monomer. It Of course, the acrylic copolymer used in the practice of the present invention is compatible with gelatin and has a Tg (glass transition temperature) of 20 ° C or lower. (Tg: “Techniques and Methods
f Polymer Evaluation) ”, Vol. 1, Marcel Dekker, I
nc., NY, 1966 and can be calculated by the differential thermal analysis. ) A particularly preferred polymer latex for use in the silver halide emulsion layer is poly (methyl acrylate-co-2-acrylamido-2-methylpropane sulfonic acid) consisting of repeating units of the formula:

[0028]

[Chemical 3]

The thickness of the radiation-sensitive silver halide emulsion layers in the photographic elements of this invention is typically in the range of about 1 / about 9 microns, and more preferably about 2 to about 4 microns. It is within the range. The total concentration of silver in the novel photographic elements of this invention is typically about 0.5 to about silver per square meter.
It is in the range of 5.5 grams, preferably in the range of about 1.5 to about 4.5 grams of silver per square meter, and most preferably about 2.5 to about 3.5 of silver per square meter.
Within the gram range. The novel photographic elements of this invention can contain an overcoat layer containing a hydrophilic colloid and a matting agent. The hydrophilic colloid can be selected from among those previously described as being useful in emulsion layers. More preferably, the hydrophilic colloid in the overcoat layer is gelatin.

[0030] Discrete solid particles of matting agent, typically having an average particle size in the range of about 1 to about 5 microns, and preferably in the range of about 2 to 4 microns, are present in the overcoat layer. Available. Matting agents are typically used in amounts of about 0.02 to about 1 part per part by weight of hydrophilic colloid. Either organic or inorganic matting agents can be used. Specific examples of organic matting agents include polymers such as polymers of esters of acrylic acid and methacrylic acid such as poly (methylmethacrylate), cellulose esters such as cellulose acetate propionate, cellulose ethers, ethyl cellulose, polyvinyl. Resins,
For example, particles such as poly (vinyl acetate), styrene polymers and copolymers (often in the form of beads). Specific examples of the inorganic matting agent are particles of glass, silicon dioxide, titanium dioxide, magnesium oxide, aluminum oxide, barium sulfate, calcium carbonate and the like.
Matting agents and their uses are described in detail in US Pat. Nos. 3,411,907 and 3,754,924.

The particles used in the present invention for the matting agent may be of virtually any shape. Their size is typically defined in terms of mean diameter. The average diameter of a particle is defined as the diameter of a spherical particle of the same mass. Polymer particles in the form of spherical beads are preferred for use as matting agents. The thickness of the overcoat layer is typically in the range of about 0.2 to about 1 micron, preferably about
It is in the range of 0.3 to about 0.6 microns, and most preferably in the range of about 0.35 to about 0.45 microns. An antihalation layer is typically coated on the support opposite the emulsion layer. Its function is to prevent light passing through the film support from reflecting into the imageable layer, thereby causing undesired image spreading known as halation. The antihalation layer may then be overcoated with another layer which serves as a protective outermost layer. Alternatively, antihalation protection can be provided by incorporating a non-migrating dye in the layer below the emulsion layer.

With respect to lithographic (lith) photographic elements, the room light-handleable high contrast elements of the present invention are preferably utilized (exposed and processed) as sheet films. As such, preferably the film has low curl (ie, at 21 ° C. and 15% relative humidity, ANSI pH 1.
Using 29-1971, no more than about 40 ANSI curl units, which is the radius of curvature curve that fits the curl of the sample strip to the shape of the radius variability curve and gives a curl of 100
/ R value (where R is the radius of curvature expressed in inches) and high dimensional stability (% change in linear dimension divided by 21 ° C relative humidity range 15- Moisture coefficient, less than about 0.0015, defined as the change in percent humidity over 50%. In the photographic elements of this invention, an intermediate layer of hydrophilic colloid and polymer latex can be placed between the silver halide emulsion layer and the overcoat layer.

The main use of the interlayer is to avoid or at least reduce the "starry night" effect. This well known effect can result from the matting agent particles in the overcoat layer penetrating the silver halide emulsion layer. The image density in the areas subbed with the matting agent particles is reduced compared to other areas of the emulsion layer which receive equal exposure. These areas of low image density appear as small spots in the image. The resulting visual effect has been called the "starry night" effect, due to its appearance similar to the starry night sky. The intermediate layer consists of a mixture of polymer latex and hydrophilic colloid. The application of the polymer latex is to give the film the requisite dimensional stability, for which it is used in an amount of about 0.2 to about 1.5 parts per part by weight of hydrophilic colloid. The hydrophilic colloid incorporated in the intermediate layer can be selected from those previously described as useful in the emulsion layer and can be the same or different from the particular hydrophilic colloid used in the emulsion layer. Good. More preferably, the hydrophilic colloid in the intermediate layer is gelatin. The polymer latex incorporated into the intermediate layer can be selected from those previously described as useful for the emulsion layer and can be the same or different than the polymer latex used for the emulsion layer. More preferably, the polymer latex in the intermediate layer is poly (methyl acrylate-co-2-acrylamido-2-methylpropane sulfonic acid).

The thickness of the intermediate layer is typically about 0.5 to about 5.
In the micron range, preferably in the range of about 0.8 to about 3.5 microns, and most preferably about 1.7 to
Within the range of about 3 microns. In a particularly preferred embodiment of the present invention the silver halide grains are such that the average grain size of the grains is about 0.1 micrometer, the dopant comprises ruthenium and the dopant is in the amount of about 3 × 10 ^-4 moles per mole silver. The silver chloride grains are present therein and 100 weight percent of the total amount of dopant in the grain is within the outer 90 percent of the total grain volume. In the examples reported herein below, a developer concentrate was formulated as follows and diluted at a ratio of 1 part concentrate to 4 parts water to give a working strength developer at pH 10.4. Was generated.

Sodium metabisulfite 145 g 45% potassium hydroxide 178 g Diethylenetriaminepentaacetic acid pentasodium salt (40% solution) 15 g Sodium bromide 12 g Hydroquinone 65 g 1-Phenyl-4-hydroxymethyl-4-methyl-3-pyrazolidone 2. 9 g benzotriazole 0.4 g 1-phenyl-5-mercaptotetrazole 0.05 g 50% sodium hydroxide 46 g boric acid 6.9 g diethylene glycol 120 g 47% potassium carbonate 120 g Water was added to make 1 liter.

The present invention will be described more specifically by the following examples of the present invention. Examples 1 to 4 Using K ₂ Ru (NO) Br ₅ as a doping agent,
A high-contrast black-and-white photographic element handleable in room light according to the present invention was prepared. The elements are, in order, on one side of a poly (ethylene terephthalate) film support, a high chloride silver halide fine grain emulsion layer, an intermediate layer containing gelatin and a latex polymer, and an overcoat containing gelatin and a matting agent. It consists of a support having a coating layer and, on the opposite side, an antihalation layer containing gelatin, a latex polymer and an antihalation dye, and a protective layer containing gelatin and a matting agent. The silver halide grains were 100 percent chloride and had an average grain size of 0.09 micrometers.

For silver chloride emulsion precipitation, both AgNO ₃ and NaCl solutions were simultaneously added at constant flow rates to a well-stirred reaction vessel containing gel / water at pH 3.0.
The total treatment time for both reactants was 15 minutes and the temperature of the reaction vessel was maintained at 25 ° C. Emulsion precipitation was adjusted to mv value +141. Emulsion at 40 ° C until conductivity of 3.6 ms is reached
Ultrafiltered with. Final pH is 4.5, and final mV
The value was +211. In the control test, the dopant start time, i.e., the length of time that elapsed between the start of precipitation and the start of dopant addition, was 30 seconds, and the dopant interval time, i.e., the total time interval in which the dopant was added. Was for 30 seconds. In Examples 1 to 4,
Either the dopant start time or the dopant interval time or both were different from those used in the control test, as described in Table I below. Exposure of control test and photographic elements of Examples 1 to 4 in an exposure apparatus equipped with an iron-doped metal halide light source and 35 ° C.
Processing time was 22 seconds and the processing was carried out using the above developing solution. Intermittent exposure and solarization were evaluated according to the following test methods.

Intermittent Exposure Test (1) 1.0 A median density filter was placed on the tripartite midsection of a 35 mm film strip. (2) The strip was exposed to 30 units using an iron-doped metal halide light source. (3) Remove the intermediate density filter and wait for 2 minutes. (4) Covered the triplicate top of the strip that first received 30 units of exposure. (5) The strip was exposed for another 30 units. The results show that the triplicate upper part of the strip received 30 units of exposure, the trisection middle part received 30 units of exposure attenuated by a 1.0 mid-density filter, followed by 30 units of exposure, and the trisection low The department will receive two exposures of 30 units. (6) The density of each area was read and recorded.

Solarization Test (1) Each film strip was exposed with 94, 148, 236, 374, 598 and 944 units using the exposure frame. (2) The density was read and recorded. The results obtained are summarized in Table I below.

[0040]

[Table 1]

Comparing Example 1 with the control test, the dopant spacing time was increased and the dopant
It is observed that as the band width increases, Dmax increases in both the solarization test and the intermittent exposure test. A comparison of Example 2 with Example 1 shows that Dmax further increases in both tests as the dopant spacing time is further increased and therefore the band width is further increased. Comparing Example 3 with the control test, the dopant initiation time increased and the position of the dopant band moved accordingly closer to the surface of the grain, with Dma in both tests.
It shows that x increases further. Comparison of Example 4 with Example 3 shows that increasing the dopant spacing time while keeping the dopant onset time constant increases Dmax further in both tests. In the control test, no dopant is present within the outer 90% of the total grain volume. In each of Examples 1-4,
More than 25 weight percent of the dopant, i.e. 40, 65, 100 and 100 weight percent for Examples 1-4, respectively, are present within the outer 90 percent of the total particle volume. In Examples 3 and 4, which represent particularly preferred embodiments of the invention, all dopants are within the outer 90 percent of the total grain volume. As the data clearly show, adjusting the dopant position in the manner described herein effectively solves both solarization and intermittent exposure problems.

Claims (4)

[Claims] 1. A high-contrast black-and-white silver halide photographic element handleable under room light, which is specially adapted for the field of graphic arts, said element comprising a nitrosyl or thionitrosyl ligand and a periodic table of the elements. Support for supporting a silver halide emulsion layer containing high chloride radiation-sensitive silver halide fine particles having a face-centered cubic crystal lattice structure, containing a dopant composed of a transition metal selected from Groups 5 to 10 therein Wherein the dopant is present in the particle in an amount sufficient to reduce the speed of the element and enhance contrast, wherein at least 25 weight percent of the total amount of the dopant in the particle is the total particle volume. 90% from the outside of the emulsion to reduce solarization and intermittent exposure effects of the emulsion, thereby maximizing the maximum of the element. Photographic elements characterized by increasing density. 2. The dopant is selected from the following formula [ML ₄ (NY) L ′] ⁿ (wherein, M is a transition metal selected from Groups 5 to 10 of the periodic table of elements, and L Is a binding ligand, L'is L or (NY), Y is oxygen or sulfur, and n is zero,-
The photographic element of claim 1, wherein the photographic element is 1, -2 or -3). 3. The dopant according to the following formula [M ¹ (NO) (L ¹ ) ₅ ] ^m (wherein, m is zero, -1, -2 or -3, and M ¹ is chromium. , Rhenium, ruthenium, osmium or iridium, and L ¹ is one or a combination of halide and cyanide ligands, or up to two aco ligands and these ligands. A photographic element according to claim 1, designated as a combination). 4. The photographic element of claim 1, wherein the transition metal is ruthenium.