GB1593751A - Light-sensitive silver halide photographic material - Google Patents

Description

(54) LIGHT-SENSITIVE SILVER HALIDE PHOTOGRAPHIC MATERIAL (71) We, KONISHIROKU PHOTO INDUSTRY CO. LTD., a Corporation organized and existing under the laws of Japan, Qf 1--10, 3-chome, Nihonbashi-Muro-machi, Chuo-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a novel light-sensitive silver halide photographic material. Particularly, it relates to a novel lith type light-sensitive silver halide photographic material for obtaining a photographic image with an especially high-contrast, high sharpness and high resolving power.

More particularly, it relates to novel light-sensitive silver halide photographic material which is applicable advantageously to a light-sensitive silver halide photographic material with a high-contrast suitable for forming a dot- or lineimage on a lith (printing) light-sensitive silver halide material or a copying lightsensitive material.

It has been known to form a photographic image with an extremely high contrast by using some kind of a light-sensitive silver halide photographic material.

It has been known, for example, to obtain a high-contrast image, e.g. a lineor dot-image by processing, with an alkaline hydroquinones developing solution containing sulfite ions in a very low concentration, a light-sensitive material which comprises a silver chlorobromide emulsion containing silver chloride in a high content (at least more than 50 mole%), the grains of which emulsion being minute (average grain size; ca. 0.2 ,u), uniform in size and shape, and the grain size distribution thereof being narrow. The above-mentioned kind of light-sensitive silver halide material is known as the lith type light-sensitive material.

In printing, there is usually required such a process as to convert a continuous gradation original to a dot image; that is a process to convert the densities of the continuous gradation to a predetermined numbered assembly of dots respectively having areas of the same densities but proportional in size to the densities of the continuous gradation. In order to carry out this, the lith type light-sensitive material is subjected to development, after photographing the original image through a cross- or contact-screen, to form the dot image on the light-sensitive material.

For this purpose there has been employed a light-sensitive silver halide photographic material containing a silver halide emulsion, the grains of which being minute and being uniform in size and shape. Even when this kind of a lightsensitive silver halide photographic material is employed, the intermediate density region (undesirable continuous gradation parts) is reproduced, beside the maximum density region and the minimum one (fog), when the material is processed with a standard black and white developing solution. The intermediate density region or the so-called flinge, undesirable for producing a printing plate makes the dot quality worse.

In order to avoid this there has been employed, as mentioned above, a specific developing solution called "infectious developing solution". It is indispensable, however, to maintain the sulfite concentration in the infectious developing solution as low as possible to obtain a high contrast image, but such the developing solution is very poor in storability because of the low concentration of the sulfite so that this have caused a big trouble in printing business. Every effort has been made, however, to improve the storability.

Nevertheless, such efforts have not been so successful. As a result, an ordinary developing solution for a continuous gradation, such as Metol/hydroquinone or Phenidone/hydroquinone developing solution which is excellent in the storability, is recommended for processing the light-sensitive materials. ("Phenidone" is a Registered Trade Mark.) However there has been known no method capable of obtaining a dot image with a good dot quality, by using such the developing solution.

On the other hand, X-ray light-sensitive materials for industrial are known as light-sensitive materials having high-contrast. But, as they are developed after they are exposed to X-ray, they have defects that they are very low in contrast compared with light-exposure.

Therefore, X-ray light-sensitive materials for industrial use have been expected to have much higher contrast from their intended object.

But every trial to enhancing contrast had resulted in desensitization of a lightsensitive silver halide photographic material and so there has been a strong need for developing a light-sensitive material having high sensitivity and high-contrast for this end. After extensive research for forming silver images with extremely high-contrast which are obtained by a treating solution with a better storability, we have found that this can be accomplished by treating a black and white lightsensitive material containing a non-diffusible compound having oxidation power on a hydroquinone developing agent in a hydrophilic colloidal layer, after lightexposure, with a developer containing a developing agent such as hydroquinone type, para-aminophenol type and paraphenylene-diamine type agent.

In connection with the above previous proposals we refer to British Patent 1,560,544 and Application 31451/77. Also concerning light-sensitive materials containing diffusible tetrazolium compounds and using a silver halide emulsion, the grain size distribution of which is uniform we refer to British Patent Application 31450/77 (Serial No. 1,589,594). This method of treating a highcontrast light-sensitive material with a developer containing a hydroquinone developing agent is an advance as compared with the known procedures.

However, by only incorporating a non-diffusible compound having oxidation power, for example, a non-diffusible tetrazolium compound into a light-sensitive material there are problems in practical use.

Especially there is a great problem in extremely high-contrast light-sensitive materials for printing use such as are used for photographing manuscripts through a cross screen or contact screen and there can be obtained relative high-contrast images compared with conventional materials. But this is not enough and there has been no solution for the so-called worm-eaten phenomena such as a dot having a chipped edge or a hole.

In such a system for obtaining high-contrast images by using light-sensitive materials containing a substantially non-diffusible compound having oxidation power, the properties of said compounds are expected be an important function for determining characteristics of the images. but even if said compound is the same, in cases where the situation of the compound being incorporated into the light-sensitive material is different, it has been found from the results of research that a great effect for the characteristics results.

This invention provides a light-sensitive material giving high-contrast images.

It also provides a novel lith type light-sensitive material suitable for obtaining excellent line-images or dot-images.

It also provides a light-sensitive material giving dot images which result in socalled worm-eaten phenomena.

According to the present invention there is provided a light-sensitive material provided with a photographic element layer including a silver halide emulsion layer coated on a support, said photographic element layer being incorporated with a tetrazolium compound (hereinafter, referred to the tetrazolium compound according to this invention) which is dispersed in a non-diffusible state so as to have an average grain size of not more than 1.0 y.

By using a tetrazolium compound which is dispersed in a state of not more than 1.0 y as in this invention, the shape of dots obtained results in a uniform appearance and dot images composed of dots having uniform areas at the same light-exposure amount part can be formed.

The photographic element layer means an image-forming layer, and a protecting layer and a supplementary layer for forming images in a light-sensitive material and concretely a silver halide light-sensitive layer and a hydrophilic layer provided when necessary with layers such as a protecting colloidal layer, intermediate layer, subbing layer, filter layer and anti-halation layer coated on a support.

Also, the average grain size of the tetrazolium compound dispersed in a nondiffusible state means a substantial dispersed grain diameter of the compound incorporated into the light-sensitive material. That is, the average grain size of the tetrazolium compound dispersed in a non-diffusible state means the average diameter of the particles where said tetrazolium compound is oily and an average of the longest dimension of the crystals in cases where it is crystalline. A nondiffusible state means a state in which the compound does not elute out in a processing solution from the light-sensitive material and more specifically such a state that after a material composed of a hydrophilic colloidal layer containing a tetrazolium compound is dipped into an aqueous solution at 300C for 10 minutes having the same ion strength and ion concentration as in a developer, as explained hereinafter, over 10%, preferably over 2% of the compound does not elute out into the aqueous solution. A material provided with a hydrophilic colloidal layer containing a tetrazolium compound on a support may be prepared and dipped into a developer having a composition as stated after at 300C for 10 minutes. After this, the tetrazolium compound in the material is reduced to a formazan dye and an eluting rate of the tetrazolium compound into the developer, that is, a remaining amount (y) of it is measured by means of a colorimetry. Over 90% of y means a non-diffusible state according to this invention. Over 98% of y is especially preferable and gives a high gamma.

Light-sensitive materials containing a non-diffusible tetrazolium compound in a photographic constitutional element layer are disclosed in British Patent 1,560,544 and Applications 31451/77 and 31450/77, as already described. But there is no disclosure in which a tetrazolium compound is dispersed with an average grain size of not more than 1.0 ,u. The average grain size of a tetrazolium compound of this invention is not more than 1.0 u preferably 1.0 tL--0.001 , especially preferably not more than 0.5 y. It is preferable that the grain size distribution is uniform. Such a dispersion state can be confirmed by an optical microscope or an electron microscope and also observed by a spectrophotometer and a turbidmetry. Further those skilled in the art can observe a dispersion state by examining a photographic material in which the silver halide is removed with the naked eye.

As to methods of dispersing a tetrazolium compound in a non-diffusible state, there can be adopted known and optional methods. But representative methods which are relatively simple and industrially applicable are as follows: (1) a method of adding a substantially water-insoluble tetrazolium compound dissolved in a water-miscible solvent into water or an aqueous gelatin solution with vigorous shaking little by little.

(2) a method of dissolving an anionic counter ion, as described after, into an aqueous solution in which a hydrophilic colloid such as gelatin is dissolved and adding a water-soluble tetrazolium compound into said solution with vigorous shaking little by little. This method makes the tetrazolium compound non-watersoluble and non-diffusible at the same time. But this method can be carried out by adding the tetrazolium compound into a hydrophilic colloid to give a solution and adding an anionic counter ion into the solution or adding a water-soluble tetrazolium compound and an anionic counter ion at the same time into a hydrophilic colloidal solution.

(3) a method of dissolving a tetrazolium compound in a solvent having a high boiling point and/or low boiling point to obtain a solution and dispersing protectively the solution in water or a hydrophilic colloidal layer by a known method.

(4) a method of adding and mixing a tetrazolium compound into an aqueous solution containing polymer particles to incorporate the tetrazolium compound into the polymer particles.

In method (1), water-miscible solvents are, for example, acetone, ethylalcohol, methylalcohol, isopropylalcohol, methyl ethyl ketone, tetrahydrofuran, N - methylpyrolidone, dimethylformamide and dimethylsulfoxide. These solvents can be used alone or in combination of two or more of these solvents. Also, as to tetrazolium compounds, the tetrazolium compound such as are concretely described after can be preferably used. Among them, diffusible compounds can be made in a non-diffusible state of this invention by dispersing protectively them or reacting them with a counter ion having a relatively large molecular weight. As to hydrophilic colloid uscd for various dispersion, gelatin is representative but a gelatin derivative such as phthalized gelatin and malonated gelatin, colloidal albumin, agar, arabian gum, arginic acid, a hydrolyzed cellulose acetate, acrylamide, an imidated polyamide, polyvinyl alcohol, a hydrolyzed polyvinyl alcohol, water-soluble polymer, a phenylcarbamyl gelatin, a polymer in which a monomer such as an acrylic acid, styrene, acrylate, methacrylic acid or methacrylate, is graft-polymerized with gelatin can be used instead of a part of gelatin or all the part of it. These hydrophilic colloids may be a solution incorporated with a silver halide as well as various additives.

Also, as to homogenizers used in method (3), there are various type of homogenizers which are marketed as a colloid mill, a Manton-gaulin homogenizer manufactured by Manton-gaulin Manufacturing Industry Co. or ultrasonic homogenizer. In the case of a tetrazolium compound being solid, as it is difficult to be homogenized as it is, it is preferably dispersed by a homogenizer after it is dissolved in a suitable non-aqueous solvent.

Non-aqueous solvents are usual solvents used for dispersion of usual photographic couplers such as, solvents having a low boiling point such as methanol, methyl acetate, ethyl acetate, butyl acetate, and tetrahydrofuran and solvents having a high boiling point such as dibutylphthalate, tricresylphosphate, triphenylphosphate, dioctylphthalate, N,N - diethylacrylamide, N,N diethyllaurylamide and fluorinated paraffine. These solvents are used alone or in combination of two or more of them. In the same way as in dispersion of photographic couplers, the tetrazolium compound can be easily dispersed in the case of using an anionic, cationic, nonionic and/or amphoteric surface active agent.

As to method (4), latexes disclosed In Japanese Laid-Open Public Patent Publications (hereinafter, referred to as PPP) 59942/1976, 59943/1976 and 74538/1974 are used and can be dispersed in the same way as in method (3).

The representative salt of tetrazolium compounds employed in the invention include the following compounds represented by the general formulae:

In formulae Ill, Ill] and [III], Rl, R3, R5, R8, R9, Rlo and R" each represent a hydrogen, nitro, mercapto, an amino group, an alkyl group such as methyl, ethyl, propyl and butyl (preferably an alkyl having 1--22 carbon atons) an alkenyl group such as ethenyl, allyl and butenyl, an aryl group such as phenyl and naphthyl or a heterocyclic group (preferably 5---6 membered heterocyclic group containing nitrogen. oxygen and/or sulfur) such as oxazolyl, thiazolyl, imidazolyl, benzoxazolyl, benzothiazolyl, benzoimidazolyl, selenazoyl, benzoselenazolyl, naphthoxazolyl, pyridyl, pyrimidinyl, indazolyl, furyl, oxazinyl, morpholino, piperidyl and tetrazolyl and these may be groups such as are capable of forming metal chelates or complexes. R2, R6 and R, each represents a hydrogen, hydroxyl, carboxyl, mercapto, nitro, an amino group, an alkyl group (preferably alkyl having 1--22 carbon atoms) such as methyl, ethyl, propyl, butyl, hexyl, octyl and dodecyl, an aryl group such as phenyl and naphthyl, a heterocyclic group (preferably 5-6 membered heterocyclic group containing nitrogen, oxygen and/or sulfur) such as defined above, an alkoxycarbonyl group such as methoxycarbonyl and ethoxycarbonyl, an alkenyl group such as allyl and butenyl; D represents arylene such as phenylene, naphthylene; E represents alkylene such as methylene, ethylene, trimethylene, pentamethylene, octamethylene, propylene and butylene, arylene such as phenylene and naphthylene, aralkylene such as tolylene and xylylene; X represents an anionic ion forming atom such as a chloride ion or a bromide ion, or atomic group such as a perchloriate ion, sulfonate ion, nitrate ion or p-toluene sulfonate ion; and n represents an integer of 1 to 2 providing that n is 1 when the compounds forms an intramolecular salt. Compounds having formula [I] are preferable in this invention, further compounds having an aryl group in R, R2 and R3 are preferable, and furthermore a compound having a phenyl group R, and R2 and R3 are more preferable.

The groups in all the general formulas include the substituted ones as explained before.

Although the substituents may be any substituents, preferred ones are one or more appropriately selected from the groups consisting of halogen, nitro, cyano hydroxy, sulfo, carboxy, an amino group, an alkyl group, an alkenyl group, an aryl group, an alkoxy group, and alkoxycarbonyl group, an acryl group, an acyloxy group, an acylamino group, a heterocyclic group, a carbamoyl group, a sulfamoyl group, a sulfonamido group, an aryloxy group, an alkenyloxy group.

The following are typical examples of the cationic moieties of the tetrazolium compounds represented by the formula used in this invention but not intended to limit the tetrazolium compound thereof.

(1) 2 - (benzothiazol - 2 - yl) - 3 - phenyl - 5 - dodecyl - 2H - tetrazolium (2) 2,3 - diphenyl - 5 - (4 - t - octyloxyphenyl) - 2H - tetrazolium (3) 2,3,5 - triphenyl - 2H - tetrazolium (4) 2,3,5 - tri(P - carboxyethylphenyl) - 2H - tetrazolium (5) 2 - (benzothiazol - 2 - yl) - 3 - phenyl - 5 - (o - chlorophenyl) - 2H tetrazolium (6) 2,3 - diphenyl - 2H - tetrazolium (7) 2,3 - diphenyl - 5 - methyl - 2H - tetrazolium (8) 3 - (p - hydroxyphenyl) - 5 - methyl - 2 - phenyl - 2H - tetrazolium (9) 2,3 - diphenyl - 5 - ethyl - 2H - tetrazolium (10) 2,3 - diphenyl - 5 - n - hexyl - 2H - tetrazolium (11) 5 - cyano - 2,3 - diphenyl - 2H - tetrazolium (12) 2 - (benzothiazol - 2 - yl) - 5 - phenyl - 3 - (4 - tolyl) - 2H tetrazolium (13) 2 - (benzothiazol - 2 - yl) - 5 - (4 - chlorophenyl) - 3 - (4 nitrophenyl) - 2H - tetrazolium (14) 5 - ethoxycarbonyl - 2,3 - di(3 - nitrophenyl - 2H - tetrazolium (15) 5 - acetyl - 2,3 - di(p - ethoxyphenyl) - 2H - tetrazolium (16) 2,5 - diphenyl - 3 - (p - tolyl) - 2H - tetrazolium (17) 2,5 - diphenyl - 3 - (p - iodophenyl) - 2H - tetrazolium (18) 2,3 - diphenyl - 5 - (p - phenyl - phenyl) - 2H - tetrazolium (19) 5 - (p - bromophenyl) - 2 - phenyl - 3 - (2,4,6 - trichlorophenyl) - 2H tetrazolium (20) 3 - (p - hydroxyphenyl) 5 - (p - nitrophenyl) - 2 - phenyl - 2H tetrazolium (21) 5 - (3,4 - dimethoxyphenyl) - 3 - (2 - ethoxyphenyl)- 2 - (4 methoxyphenyl) - 2H - tetrazolium (22) 5 - (4 - cyanophenyl) - 2,3 - diphenyl - 2H - tetrazolium (23)3 - (p - acetamidophenyl) - 2,5 - diphenyl - 2H - tetrazolium (24) 5 - acetyl - 2,3 - diphenyl - 2H - tetrazolium (25) 5 - (fur - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium (26) 5 - (thien - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium (27) 2,3 - diphenyl - 5 - (pyrid - 4 - yl) - 2H - tetrazolium (28) 2,3 - diphenyl - 5 - (quinol - 2 - yl) - 2H - tetrazolium (29) 2,3 - diphenyl - 5 - (benzoxazol - 2 - yl) - 2H - tetrazolium (30) 2,3 - diphenyl - 5 - nitro - 2H - tetrazolium (31) 2,2',3,3' - tetraphenyl - 5,5',1,4 - butylene - di(2H - tetrazolium) (32) 2,2',3,3' - tetraphenyl - 5,5' - p - phenylene - di(211 - tetrazolium) (33) 2 - (4,5 - dimethylthiazol - 2 - yl) - 3,5 - diphenyl - 2H - tetrazolium (34) 3,5 - diphenyl - 2 - (triazin - 2 - yl) - 2H - tetrazolium (35) 2 - (benzothiazol - 2 - yl) - 3 - (4 - methoxyphenyl) - 5 - phenyl - 2H tetrazolium (36) 2 - p - iodophenyl - 3 - p - nitrophenyl - 5 - phenyl - 2H - tetrazolium.

As the anion moiety capable of combining with tetrazolium compounds, there can be mentioned, e.g. halogen ion such as a chlorine or bromine ion, sulfate ion, nitrate ion, per chlorate ion, alkylarylsulfonate ion (preferably alkyl having 1--22 carbon atoms) such as p - p- toluenesulfonate ion, p dodecylbenzenesulfonate ion, propylnaphthalenesulfonate ion, higher alkylsulfate ion (having 8-22 carbon atoms) such as an octylsulfate ion, a dodecylsulfate ion, and an octadecylsulfate ion, a dialkylsulfosuccinate ion (preferably alkyl having 1--22 carbon atoms) such as a di - 2 - ethylhexylsulfosuccinate ion, a di - n octylsulfosuccinate ion, a polyetheralcoholsulfate ion such as a cetylpolyethenoxysulfate anion and an amylphenoxypolyethenoxysuccinate sulfate ion, higher alkyl carboxylic ion (having 8-32 carbon atoms) such as a lauric acid anion and a stearic acid anion and nionic polymer such as a polyacrylic acid anion. Preferably can be mentioned, as the anion, an alkylarylsulfonate ion, a higher alkylsulfate ion, a dialkylsulfosuccinate ion, a polyetheralcoholsulfate ion, a higher alkyl carboxylic ion and an anionic polymer.

In cases where diffusible compounds among tetrazolium compounds of this invention are used as non-diffusible compounds, the non-diffusible compounds can be prepared by reacting the diffusible compounds with suitable anions.

The following are typical examples of the salt of tetrazolium compound represented by the formula used in this invention but not intended to limit the tetrazolium compound thereof.

(37) 2 - (benzothiazol - 2 - yl) - 3 - phenyl - 5 - dodecyl - 211 - tetrazolium stearate (38) 2,3 - diphenyl - 5 - (4 - t - octyloxyphenyl) - 2H - tetrazolium laurate (39) 2,3,5 - triphenyl - 2H - tetrazolium di - 2 - ethylhexylsulfosuccinate (40) 2,3,5 - tri(p - carboxyethylphenyl) - 2H - tetrazolium stearate (41) 2 - benzothiazol - 2 - yl) - 3 - phenyl - 5 - (o - chlorophenyl) - 2H tetrazolium p - dodecylbenzenesulfonate (42) 2,3 - diphenyl - 2H - tetrazolium di - 2 - ethylhexylsulfosuccinate (43) 2,3 - diphenyl - 5 - methyl - 2H - tetrazolium p - octylbenzene sulfonate (44) 3 - (p - hydroxyphenyl) - 5 - methyl - 2 - phenyl - 2H - tetrazolium stearate (45) 2,3 - diphenyl - 5 - ethyl - 2H - tetrazolium di - 3 - methylnonyl sulfonate (46) 2,3 - diphenyl - 5 - n - hexyl - 2H - tetrazolium p - octadecyl benzenesulfonate (47) 5 - cyano - 2,3 - diphenyl - 2H - tetrazolium di - 2 - ethylhexyl sulfosuccinate (48) 2 - (benzothiazol - 2 - yl) - 5 - phenyl - 3 - (4 - tolyl) - 2H tetrazolium p - dodecylbenzenesulfonate (49) 2 - (benzothiazol - 2 - yl) - 5 - (4 - chlorophenyl) - 3 - (4 nitrophenyl) - 2H - tetrazolium di - isopropylnaphthalenesulfonate (50) 5 - ethoxycarbonyl - 2,3 - di(3 - nitrophenyl) - 2H - tetrazolium stearate (51) 5 - acetyl - 2,3 - di(p - ethoxyphenyl) - 2H - tetrazolium laurate (52) 2,5 - diphenyl - 3 - (p - tolyl) - 2H - tetrazolium stearate (53) 2,5 - diphenyl - 3 - (p - iodophenyl) - 2H - tetrazolium laurate (54) 2,3 - diphenyl - 5 - (p - phenyl - phenyl) - 2H - tetrazolium di isopropylnaphthalenesulfonate (55) 5 - (p - bromophenyl) - 2 - phenyl - 3 - (2,4,6 - trichlorophenyl) - 2H tetrazolium di - isopropylnaphthalene - di - sulfonate (56)3 - (p - hydroxyphenyl) - 5 - (p - nitrophenyl) - 2 - phenyl - 2H - tetrazolium p - dodecylbenzenesulfonate (57) 5 - (3,4 - dimethoxyphenyl) - 3 - (2 - ethoxyphenyl) - 2 - (4 methoxyphenyl) - 2H - tetrazolium di - 2 - ethylhexylsulfosuccinate (58) 5 - (4 - cyanophenyl) - 2,3 - diphenyl - 2H - tetrazolium laurate (59) 3 - (p - acetamidophenyl) - 2,5 - diphenyl - 2H - tetrazolium stearate (60) 5 - acetyl - 2,3 - diphenyl - 2H - tetrazolium p - octadecylbenzenesulfonate.

(61)5 - (fur - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium di - 2 - ethyl hexylsulfonate (62) 5 - (thien - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium stearate (63) 2,3 - diphenyl - 5 - (pyrid - 4 - yl) - 2H - tetrazolium laurate (64 2,3 - diphenyl - 5 - (quinol - 2 - yl) - 2H - tetrazolium stearate (65) 2,3 - diphenyl - 5 - (benzoxazol - 2 - yl) - 2H - tetrazolium laurate (66) 2,3 - diphenyl - 5 - nitro - 2H - tetrazolium di - isopropylnaphthalenesulfonate (67) 2,2',3,3' - tetraphenyl - 5,5',1,4 - butylene - di(2H - tetrazolium) di 3 - propylnonylsulfonate (68) 2,2',3,3' - tetraphenyl - 5,5' - p - phenylene - di(2H - tetrazolium) p dodecylbenzenesulfonate (69) 2 - (4,5 - dimethylthiazol - 2 - yl) - 3,5 - diphenyl - 2H - tetrazolium stearate (70) 3,5 - diphenyl - 2 - (triazin - 2 - yl) - 2H - tetrazolium laurate (71) 2 - (benzothiazol - 2 - yl) - 3 - (4 - methoxyphenyl) - 5 - phenyl - 2H tetrazolium p - toluenesulfonate (72) 2 - p - iodophenyl - 3 - p - nitrophenyl - 5 - phenyl - 211 - tetrazolium di - isopropylnaphthalene - di - sulfonate (73) 2,3,5 - triphenyl - 2H - tetrazolium di - isopropylnaphthalene - di sulfonate.

The tetrazolium compounds of this invention can be easily prepared by the methods described in Chemical Review, Vol. 55, P. 33583.

According to a preferred embodiment of the invention, the tetrazolium compound of the invention is incorporated into a silver halide emulsion layer.

According to another preferred embodiment of the invention, the compound is incorporated in a layer adjacent directly or a layer adjacent to said adjacent layer to the layer containing the silver halide emulsion.

The above-mentioned compounds of the invention may preferably be employed in an amount of 0.0001-10 mole, more preferably 0.001-1 mole, per mole of the silver halide contained in the light-sensitive silver halide photographic material of the invention.

According to the most preferred embodiment of this invention, the silver halide of this invention has an average grain size of 0.15 to 0.5 N and is silver chloroiodobromide or silver chlorobromide, over 80% of the whole grains of which is 0.7 to 1.3 times the average grain size.

The silver halide emulsion of the invention may be sensitized with various kinds of chemical sensitizers. As the sensitizer, there can be mentioned, for example, activated gelatin, sulfur sensitizers, selenium sensitizers, reducing sensitizers and various noble metal sensitizers represented by potassium chloroaurite, potassium auriothiocyanate, potassium chloroaurate, 2 aurosulfobenzothiazole methyl chloride, ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite. The sensitizer may be employed alone, or mixed together.

Further, the silver halide emulsions may be optically sensitized with one or more of sensitizing dyes so as to have sensitivity in a desired region of sensitive wave length.

Further the use of the above optical sensitizing dyes especially merocyanine sensitizing dyes brings forth the effect of broadening a development latitude as well as chemical sensitivity.

The silver halide emulsions may be stabilized with compounds which are disclosed in USP 2,444,607, 2,716,062, 3,342,596 and 3,512,982. In the silver halide emulsions according to this invention, latent image stabilizers of amino acid compounds containing sulfur such as are disclosed in BP 1,343,904, USP 3,821,295 and gradation regulators such as cadmium and rhodium salt can be used but sufficient high-contrast light-sensitive materials can be obtained in this invention without using gradation regulators. In order to enhance contrast in silver halide emulsion, a method of using rhodium or cadmium salts are heretofore known and are disclosed in BP 775,197, USP 3,488,709 etc. In the case of use of rhodium salts, its optimum added amount is in an extremely small quantity and extremely narrow in its range, so that the products are apt to vary widely and some problems remain unsettled in preparing stable light-sensitive material. On the other hand, in the case of use of cadmium salts, an extremely small amount should be added because, in the case of film treatment, the cadmium salt should be finally washed off, so they may contaminate the surroundings. Cadmium salts are known to hinder metabolism and to be harmful to ecological system. Cadmium can be detected not only in the air but also in body of marine animals. In view of the toxicity of cadmium and a trace of other metals and in consideration of public health and the usual ecological balance, we have provided a novel method of obtaining sufficient high-contrast light-sensitive materials without using harmful metals.

The silver halide and the tetrazolium compounds according to this invention can be incorporated into a hydrophilic colloidal layer. But the hydrophilic colloid most preferably used in this invention is gelatin. As other hydrophilic colloids than gelatin, are mentioned, e.g. colloidal albumin, agar, gum arabic, arginic acid, hydrolyzed cellulose acetate, acrylamide, imidated polyamide, polyvinyl alcohol, hydrolized polyvinyl acetate, water-soluble polymer, gelatin derivatives such as phenylcarbamyl-, acylated- or phthalated-gelatin, or graft-polymerized monomers on gelatin having the ethylene group and being capable of polymerization, such as acrylic acid and the ester thereof, styrene, a methacrylic acid and the ester thereof. Such hydrophilic colloids may also be applied to a layer containing no silver halide, e.g. an antihalation layer, a protective layer, an intermediate layer, a subbing layer, a filter layer and a backing layer.

The light-sensitive silver halide material of the invention may be prepared by coating the above-mentioned layer containing the silver halide and the tetrazolium compound of the invention on a suitable photographic support. As the representative supports employed in the invention are mentioned, e.g. a baryta paper, a polyethylene-coated pauper, a synthetic polypropylene paper, a glass plate, a cellulose acetate or cellulose nitrate film, a polyester film such as a polyethylene terephthalate film, a polyamide film, a polypropylene film, a polycarbonate film, a polystyrene film and the like. The supports are optionally selected depending on the purpose for which the light-sensitive photographic material is used.

As mentioned above, the light-sensitive silver halide photographic material of the invention comprise at least one hydrophilic colloidal layer, coated on a support, containing a silver halide of the invention and a tetrazolium compounds.

It is preferable in the light-sensitive material of the invention that a protective layer having a suitable thickness is provided. The protective layer is advantageously a gelatin layer, the thickness of which is preferably 0.1-10 ,u, more preferably 0.8-2.0 y.

There are known many lith type light-sensitive materials having a protective layer. But the protective layer in this invention has a quite different function from the known protective layer. That is, a protective layer is provided for avoiding generally unnecessary damages of silver halide emulsion layer, that is, for protecting various troubles caused on preparation of the light-sensitive material, e.g. various steps during cutting, winding, package or by the light-sensitive materials' touching with other materials during exposing or processing. But the protective layer of this invention plays an important role for stabilizing the treatments as well as protecting the silver halide emulsion layer.

The reason that the presence of the protective layer may act effectively on the stability of the image quality and of the developing process in this invention is not obvious. But this is presumed that, the protective layer may have a function to control adequately the infiltration rate of the hydroquinone, Metol and/or Phenidone from the processing solution into the light-sensitive material, or the diffusion rate of the tetrazolium compound within the light-sensitive material or therefrom to the processing solution.

Various kinds of photographic additives may optionally be added to the above-mentioned hydrophilic colloid of the invention, as far as they do not impair the effect of the invention. As the additives, there can be used, e.g. a gelatin plasticizer, a hardening agent, a surface active agent, an image stabilizer, an ultraviolet absorber, an antistaining agent, a pH adjuster, an antioxidant, an antistatic agent, a viscosity-increasing agent, a granularity improving agent, a dye, a mordant, a brightening agent, a development regulator, a matting agent, and the like.

Among the additives mentioned above, the following may particularly and preferably be employed: viscosity-increasing agents and plasticizers are such as are disclosed in USP 2,960,404, 3,656,956, 3,692,753 and 3,767,410, for example, copolymer of styrene and sodium maleate and dextran sulfate; hardening agents are several hardening agents such as aldehyde type, epoxy type, ethyleneimine type, active halogen type, vinylsulfone type, isocyanate type, sulfonate type, carbodiimide type, mucochloric acid type and acyloyl type compounds; image stabilizers are 6,6' - butylidenebis(2 - t - butyl - 4 - methylphenol) and 4,4' methylenebis(2,6 - di - t - butylphenol) and the like. Ultraviolet ray absorbers are such as are described in USP 3,253,921, 3,533,794, 3,707,375, BP 1,309,349 and 1,287,770 etc. and especially 2 - (2' - hydroxy - 5' - t butylphenyl)benzotriazole, 2 - (2' - hydroxy - 3',5' - di - t butylphenyl)benzotriazole, 2 - (2' - hydroxy - 3' - t - butyl - 5' - butylphenyl) - 5 - chlorobenzotriazole, 2 - (2' - hydroxy - 3',5' - di - t - butylphenyl) - 5 chlorobenzotriazole, and the like. As surface active agents which are used as permiability improving agents of coating aids, emulsifying agents and treatment liquid, antifogants or controller of several physical characters in light-sensitive materials, anionic, cationic, non-ionic or amphoteric compound can be used which are disclosed in BP 548,532, 1,216,389, USP 3,026,202, 3,514,293, 3,726,683, FP 202,588; mordant are such compounds as are disclosed in USP 2,113,381, 2,548,564 and the like; antistain agents are compounds such as are disclosed in USP 2,360,210, 2,728,659, 2,732,300, 3,700,453, e.g. 2 - methyl - 5 hexadecylhydroquinone, 2 - methyl - 5 - secoctadecylhydroquinone and 2,5 di - t - octylhydroquinone; antistatic agents are such compounds as are disclosed in USP 2,882,157,2,972,535 and 3,573,093 and matting agents are those such as are disclosed in BP 1,221,980, 1,307,373, USP 2,992,101, 2,956,884 and FP 1,395,544 especially silica gel having 0.5-20 N in diameter and a polymer of polymethyl acrylate of 0.5-20 N in diameter; as development accelerators, such compounds as benzylalcohol and polyethylene oxide may be used and added effectively in a treatment bath.

In accordance with the process of the invention, there is obtained a high contrast silver image. The invention is therefore applicable to various fields wherein a high contrast black and white recording is required. The light-sensitive material of the invention is, for example, applied preferably to a printing material.

The process of the invention for forming a lith type photographic image has superior characteristics which no conventional processes have reached yet. It is not necessarily elucidated why the high contrast silver image may be obtained according to the process of the invention. It is presumed that the semiquinone produced by oxidation of hydroquinone in the developing solution by the tetrazolium compound may be accumulated in an abnormally high concentration near the developed silver. It is said, in general, that the so-called "infectious phenomenon" does not take place due to instantaneous removal of the semiquinone or quinones by sulfonation when the sulfite ions are in a high concentration in the developing solution. Whereas, in the present process, it is presumed that the infectious development takes place at the position of the exposed silver halide in the gelatin matrix due to predominant supply of the semiquinone.

Therefore, in this invention there is no need for use of a so-called lith type developer (an infectious developer) and there can be obtained a lith type highcontrast silver images even in the presence of a high concentration of sulfite ions.

As in the conventional infectious developer, in this invention there is also no need to use of hydroquinone, alkali, alkali bromide, a low concentration of sulfurous acid ion and formaldehyde-sodium hydrogen sulfite or carbonylbisulfite amine condensation product as a preservative agent (the use of them is of course possible). This is different from the conventional methods. In the developers containing developing agents used in this invention, there are included so-called infectious developers as well as MQ developer (Metol-hydroquinone developer) having gradation or PQ developer (Phenidone-hydroquinone developer).

Especially, as MQ or PQ developer is excellent in preparation and storability, these developers are advantageously applicable in this invention. Such a developer is preferred to have superadditivity and such developers or development supplementary agents are disclosed in "The Theory of Photographic Process" (the Third edition, page 374 378), 1966 are preferably used.

Inorganic developing agents used in this invention are iron (11), titanium (Ill), and vanadium (11) ion and complex compound thereof, for example, ethylenediaminetetraacetic acid iron (1), iron (II) oxalate, iron (II) citrate and bis(l - hydroxy - 3 - methylcyclopentadienyl) iron (II), dithionite such as sodium dithionite, and compounds having organic substitutents such as hydroxylamine, phenylhydrazine, hydrazobenzene and phenylhydroxylamine.

Representative developing agents having HO--(CH=CH),--OH are catechol, pyrogallol and derivatives thereof and ascorbic acid and especially hydroquinone, chlorohydroquinone, bromohydroquinone, isopropylhydroquinone, toluhydroquinone, methylhydroquinine, 2,3 dichlorohydroquinone, 2,5 - dimethylhydroquinone, 2,3 - dibromohydroquinone, 2,5 - dihydroxyacetophenone, 2,5 - diethylhydroquinone. 2,5 - di - p phenethylhydroquinone, 2,5 - dibenzoylaminohydroquinone catechol, 4 chlorocatechol, 3 - phenylcatechol, 4 - phenylcatechol, 3 - methoxycatechol, 4 acetylpyrogallol, 4 - (2' - hydroxybenzoyl)pyrogallol, sodium ascorbate and the like.

Representative developing agents have HO(CH=CH)nNH2 are ortho and para - aminophenols and especially 4 - aminophenol, 2 - amino - 6 phenylphenol, 2 - amino - 4 - chloro - 6 - phenylphenol, 4 - amino - 2 phenylphenol, 3,4 - diaminophenol, 3 - methyl - 4,6 - diaminophenol, 2,4 diaminoresorcinol, 2,4,6 - triaminophenol, N - methyl - p - aminophenol, N 5 - hydroxyethyl - p - aminophenol, p - hydroxyphenylaminoacetic acid, 2 - aminonaphthol and the like.

Representative developing agents having H2NhCH=CH)nNH2 are 4 amino - 2 - methyl - N,N - diethylaniline, 2,4 - diamino - N,N - diethylaniline, N - (4 - amino - 3 - methylphenyl) - morpholine, p - phenylenediamine, 4 amino - N,N - dimethyl - 3 - hydroxyaniline, N,N,N',N' - tetramethyl paraphenylenediamine, 4 - amino - N - ethyl( - hydroxyethyl)aniline, 4amino - 3 - methyl - N - ethyl - N - (,3 - hydroxyethyl)aniline, 4 - amino - N ethyl - (P - methoxyethyl) - 3 - methyl - aniline, 4 - amino - 3 - methyl - N ethyl - N -(p - methylsulfonamidoethyl)aniline, 4 - amino - N - butyl - N - y - sulfobutyl)aniline, 1 - (4 - aminophenyl)pyrolidine, 6 - amino - 1 - ethyl 1,2,3,4 - tetrahydroquinoline, 9 - aminojurolidine and the like.

Heterocyclic developing agents are 1 - phenyl - 3 - pyrazolidone, 1 - phenyl - 4 - amino - 5 - pyrazolone, 1 - (p - aminophenyl) - 3 - amino - 2 pyrazoline, 1 - phenyl - 3 - methyl - 4 - amino - 5 - pyrazolone, 5 - aminouracil, 5 - amino - 2,4,6 - trihydroxypyrimidine and the like.

Other developing agents such as are disclosed in pages 278-3111 of "The Theory of the Photographic Process" by C. E. K. Mees and T. H. James (Third edition) and J. Am. Chem. Soc., 73 3100 (1951) are advantageously used in this invention.

These developing agents can be used alone or in combination of two or more of them but the combination of two or more is preferable. Also in the developer used in this invention, sulfite salts as sodium sulfite, potassium sulfite and ammonium sulfite can be used as preservatives without impairing the effect of this invention. This is one of the features of this invention. Also hydroxyalamine and hydrazide compounds can be used as preservatives. The adjustment of pH and giving a buffer function with an alkali hydroxide, alkali carbonate or amine, or addition of an inorganic development retarder such as potassium bromide or of an organic development retarder such as benzotriazole, of a metal ion catching agent such as ethylenediaminetetraacetic acid, of a development accelerator such as methanol, ethanol, benzylalcohol, polyalkylene oxide and the like, of an outertype coloring coupler, of a surface active agent such as sodium alkylarylsulfonate, of a hardener such as glutaraldehyde, formalin, glyoxal and the like, and of an ion concentration regulator such as sodium sulfate can be optionally carried out.

The light-sensitive material of this invention can be treated under various conditions. The development temperature is preferred to be less than 50"C, especially at about 30"C. The development time is preferred to be generally within 10 minutes, especially preferably within 5 minutes. Processing other than development, for example, water washing, stopping stabilizing, fixing, and if necessary, prehardening, neutralization and the like can be optionally adopted.

The processing may be carried out by the so-called manual processing such as a bath- or tray-development or by the mechanical processing such as a roller- or hanger development. According to a preferred embodiment of the invention, the processing solution in the bath development was more than 20 times more stabler over long period than the conventional lith type developing solution. Especially, when the known particular developing solution containing sulfite ion in an extremely low concentration is employed in order to improve the dot quality of the lith type light-sensitive material, it became of no use for several hours. While, according to a preferred method of the invention, the processing solution could be stably employed after one month has passed, and the dot quality using the solution was then comparable to that using a newly prepared solution.

Furthermore, addition of a contrast agent and a toe part cutting agent often used for the conventional high contrast developing solution to the developing solution employed in the invention gives no undesirable influence in the photographic quality.

The invention is further explained by the following Reference example and Examples, which by no means restrict the scope of the invention and various modified embodiments may be possible: Reference Example: Tests as to the Non-Diffusibility To 100 ml of a 10% gelatin solution at 400C was added 10 ml of a 10% aqueous solution of 2,3,5 - triphenyltetrazolium chloride (hereinafter, referred to as T-salt). To this mixed solution was added gradually 20 ml of a 10% solution of sodium diethylhexylsuccinate (hereinafter, referred to as DES) with vigorous shaking. The aqueous gelatin solution containing this ion pair was prepared by coating on a polyethyleneterephthalate support so as to be at an amount of 50 mg/100 cm2 of gelatin and of about 2.0 mg/100 cm2 of the ion pair of T-salt and DES based on T-salt and by drying.

Next, the diffusibility of this ion pair in a developer was examined by determining a remaining amount of the ion pair in the above sample after the sample was dipped at 300C for 10 minutes in a developer having the following composition.

[Developer Composition] Metol 3.5 g Anhydrous sodium sulfite 60g Hydroquinone 9.0 g Sodium carbonate 54g Potassium bromide 2.5 g 5-nitrobenzimidazole 0.5 g l-phenyl-5-mercaptotetrazole 10 mg Water to make 1 litre (pH=10.25) The ion pair amount of T-salt and DES remaining in the sample was measured quantitatively as an amount of T-salt as follows: The gelatin of 10 cmxl0 cm in the sample was decomposed with a 0.1% pronase solution and sodium sulfide was added to this solution to reduce T-salt to formazan dye which was completely extracted with chloroform. The chloroform solution containing this formazan dye was measured colorimetrically using 480 nm wave length.

The results were listed in Table 2 for comparison.

TABLE 2

Sample An Amount of T-salt mg/100 cm2 The untreated sample 2.03 The sample immersed 2.00 into the developer Then, the decreasing rate of T-salt in treated sample was calculated by the following equation: [T-salt amount in the untreated sample (T-salt amount in the treated samplel Decreasing rate= x100 IT-salt amount in the untreated sample 2.03-2.00 = x 100=1 48[ ' 2.03 This result showed clearly that the ion pair of T-salt and DES according to this invention was not dissolved out in the treatment liquid during development and was contained in the gelatin layer in a substantially non-diffusible state.

Example 1 The tetrazolium finely dispersed solution prepared in the same way as in Reference example was finally adjusted to 250 ml. This dispersed solution was coating on a polyethylene-terephthalate support with the silver halide so as to be in an amount of about 2.0 mg/100 cm2 calculated based on T-salt. The used silver halide emulsion was an average grain size of 0.25 ,u and composed of silver chloride of 70 mole% and silver bromide of 30 mole% and about 80% of the whole grain of the silver halide was at a range of 0.19 to 0.31 The amount of coated silver was 55 mg/100 cm2 and that of gelatin 27 mg/100 cm2. Further on this light-sensitive layer was coated gelatin in a thickness of 1.5 N to obtain Sample A.

Next, Sample B was prepared in the same way as in Sample A except that gelatin was not used in mixing of T-salt and DES and gelatin was added after aqueous solutions of both compound were mixed.

Samples A and B, after being dried, were wedge-exposed through a contact screen with a tungsten lamp and treated by the following processing (processing temperature: 380C).

Processings: Development (1.5 minutesrStopping (40 seconds)~ Fixing (2 minutes)oWater washing (5 minutes)' Drying (air drying warmed at 80"C).

The processing solutions have the following composition: [Development Compositionl Metol 3.5g Hydroquinone 9.0 g Anhydrous sodium sulfite 40 g Sodium carbonate one hydrate 50 g Potassium bromide 2.5 g 5-nitrobenzimidazole 0.5 g l-phenyl-5-mercaptotetrazole 10 mg Water to make ll p11= 10.25 [Fixer Composition] Ammonium thiosulfate 10 hydrate 150 g Anhydrous sodium phosphate 15 g Anhydrous sodium sulfite 10 g Glacial acetic acid 15 g Water to make 11 pH=4.20 [Stop Solution Composition] 2% aqueous solution of glacial acetic acid.

After the processings the results obtained are shown in Table I.

The situation of dots was evaluated as the following four grades according to the situation of fringe parts of developed silver area: Ol The fringe part of dots is very smooth and the size and shape of every dot are extremely uniform in the same light-exposed part.

X The fringe part of dots is somewhat jagged and the size and shape of dots are not a little uniform.

O The fringe part of dots is extremely jagged and the size and shape of dots are different even in the same light-exposed part. In an extreme case, the dots have parts which are almost defective.

i3 In this, there are formed silver images which can not be called almost dots.

TABLE 1

Relative Sensitivity Fog Situation of Dots Sample A 100 Situation or 0.01 Sample B 104 0.01 Also there were already formed macro-grains of about 5 iu of the tetrazolium compound in Sample B on preparation of its aqueous solution.

Example 2 This example was carried out in the same way as in Example 1 using the same sample as in Example 1 providing that 5.0 g of Metol was used instead and the development time was 2.5 minutes.

The results obtained showed the same tendency as in Example 1 and show that the light-sensitive material according to this invention has excellent characteristics.

Example 3 A silver chlorobromoiodide-gelatin emulsion composed of 90 mole% of silver chloride, 9 mole% of silver bromide and one mole% of silver iodide, an average grain size of which silver halide was 0.3,u, was chemically sensitized with sulfur and gold sensitizing agent. To this emulsion was added oleinic acid polyethylene glycol (molecular weight 1540) ester at the rate of 200 mgper one mole of silver. This silver halide emulsion thus prepared was coated on a polyethyleneterephthalate support so as to be a coated amount of 55 mg/100 cm2 of silver and 30 mg/100 cin2 of gelatin. The aqueous solutions of T-salt and sodium isopropylnaphthalenesulfonate were mixed and a precipitate was filtered out and dried to a tetrazolium compound, which was dissolved in a 2% methanol. Just before coating, the solution was added to the silver halide emulsion at the rate of 1.5 g per one mole of silver. The emulsion was stirred sufficiently on adding so as to be well mixed, thus obtaining sample C.

Sample D was prepared in the same way as in Sample C. But the tetrazolium compound and the silver halide emulsion were mixed without taking any particular procedure. Observation of Sample D with an optical microscope confirmed that there were various grain sizes of from tens N to less than 1 y of the tetrazolium. Both samples were wedge-exposed through a contact screen and were treated in the same way as in Example 1 providing that Metol of the developing agent in the developer was replaced with Phenidone. The results obtained arc shown in Table 2 and show that the light-sensitive material has excellent characteristics.

TABLE 2

Relative Sensitivity Fog Situation of Fog Sample C 100 0.01 ; Sample D 105 0.02 3-4 Even in cases where the developing agent was changed to 5 g/l of paraaminophenol, the samples showed the same tendency.

Example 4 This sample was prepared in the same way as in Sample C. But on the preparation of the tetrazolium compounds in Samples E, F, G and H the same molar proportions of 2,3 - diphenyltetrazolium perchlorate, 2,3 - diphenyl - 5 p - carboxyphenyltetrazolium chloride, 2,3 - diphenyl - 5 - methyltetrazolium chloride and 2 - (benzothiazol - 2 - yl) - 3,5 - diphenyltetrazolium bromide were respectively used in the same mole of T-salt.

Samples I, G, K and L were prepared in the same way as in Sample D of Example 3 using the corresponding Samples E, F, G and H. The results obtained are shown in Table 3.

TABLE 3

Sample Situation of Dots Sample E (within this invention) Sample F (within this invention) H Sample G (within this invention) H Sample H (within this invention) Sample I (outside of this invention) Sample G (outside of this invention) Sample K (outside of this invention) Sample L (outside of this invention) The table shows that the light-sensitive material of this invention has excellent characteristics.

Example 5 This example was prepared and treated in the same way as in Example 1. But after the tetrazolium compound is finished to 250 ml, it was coated on a support and the silver halide emulsion was coated o the support as an upper layer. The results obtained showed the same tendency a n Example I. Samples outside of this invention showed bad situation of dots.

Example 6 To 20 ml of tetrahydrofuran was dissolved 2 g of 2 - (benzothiazol - 2 - yl) 3 - phenyl - 5 - dodecyl - 2H - tetrazolium bromide and 40 ml of a 10% latex dispersed solution of a copolymer of butylacrylate, 3 - methacrylate, 3 methacryloyloxypropan - 1 - sulfonic acid sodium and 2 acetoacetoxyethylmethylacrylate (ratio of monomer=85: 10:5) was added dropwise thereto with vigorous stirring. The tetrazolium compound was added to a pure silver bromide emulsion having an average grain size of 0.25 N to obtain Sample M.

It was confirmed by a electron microscope that the original copolymer latex solution had an average grain size of about 0.1 N and had the same grain size after the solution was incorporated with the tetrazolium compound and dried.

For comparison the tetrazolium compound was added to the emulsion without being mixed with the copolymer to obtain Sample N.

The added amount of the tetrazolium compound was 5.05 g per one mole of silver and the amount of silver coated was 55 mg/100 cm2 in every case.

These samples were treated in the same way as in Example 3 and the results obtained are shown in Table 4.

TABLE 4

Specific Sensitivity Fog ; Situation of Dots Sample M 100 0.01 Sample N 103 0.02 That the sample of this invention has excellent characteristics was confirmed by such a dispersion method.

Example 7 A silver iodobromide emulsion composed of 1.5 mole of silver iodide was chemically sensitized with a gold and sulfur sensitizer and the following additives were added thereto per one mole of silver halide: 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene 1.0 g Saponin 2.5 g Glutaraldehyde 1.5 g Next, a solution of 1.8 g of 2,3,5 - triphenyl - 2H - tetrazolium chloride in 50 ml of water and a solution of 2.0 g of DES in 20 ml of methanol-water (1:1) were mixed. The resulting oily precipitate was taken out and dissolved in 5 ml of ethyl acetate. The 2 ml of didctylphthalate (DOP) was added and dissolved thereto.

This solution was mixed with a 2% aqueous gelatin solution and dispersed with an ultrasonic homogenizer.

The whole amount of the dispersed solution was added to a silver halide emulsion. The silver halide emulsion thus obtained was coated on a cellulose triacetate support to be 45 mg of silver per 100 cm2 and a gelatin layer of 12 mg/100 cm2 was provided thereon to obtain Sample P.

On the other hand, a methanol solution of 1.8 g of 2,3,5 - triphenyl - 2H tetrazolium chloride was dissolved in 2 ml of DOP and dispersed in the same way as in Sample P to give Sample Q.

Further a to methanol solution of 1.8 g of 2,3,5 - triphenyl - 2H - tetrazolium chloride was added to the silver halide emulsion to give Sample R. These samples were treated in the same way as in Example 1. The results thus obtained were shown in Table 5.

TABLE 5

Specific Situation An Average Sample Sensitivity of Dots Grain Size (,u) P 100 0.4 Q 95 O 0.4 R 85 Q3 Table 5 shows that the non-diffusible tetrazolium compound of this invention has a high sensitivity compared with the diffusible compound and an excellent dot quality.

WHAT WE CLAIM IS: 1. A light-sensitive silver halide photographic material comprising a support and a photographic element layer including a silver halide emulsion layer which photographic element layer comprises a tetrazolium compound dispersed in a nondiffusible state as herein defined, the average grain size of the compound being not more than 1.0 N as herein defined.

2. A light-sensitive silver halide photographic material according to Claim 1 wherein the photographic element layer is a silver halide emulsion layer.

3. A light-sensitive silver halide photographic material according to Claim 1 wherein hydrophilic colloidal protecting layer containing gelatin is located as an outermost layer.

4. A light-sensitive silver halide photographic material according to Claim 1 wherein the compound is represented by following formula [I], [II] or [III]:

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (17)

**WARNING** start of CLMS field may overlap end of DESC **. Example 7 A silver iodobromide emulsion composed of 1.5 mole of silver iodide was chemically sensitized with a gold and sulfur sensitizer and the following additives were added thereto per one mole of silver halide: 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene 1.0 g Saponin 2.5 g Glutaraldehyde 1.5 g Next, a solution of 1.8 g of 2,3,5 - triphenyl - 2H - tetrazolium chloride in 50 ml of water and a solution of 2.0 g of DES in 20 ml of methanol-water (1:1) were mixed. The resulting oily precipitate was taken out and dissolved in 5 ml of ethyl acetate. The 2 ml of didctylphthalate (DOP) was added and dissolved thereto. This solution was mixed with a 2% aqueous gelatin solution and dispersed with an ultrasonic homogenizer. The whole amount of the dispersed solution was added to a silver halide emulsion. The silver halide emulsion thus obtained was coated on a cellulose triacetate support to be 45 mg of silver per 100 cm2 and a gelatin layer of 12 mg/100 cm2 was provided thereon to obtain Sample P. On the other hand, a methanol solution of 1.8 g of 2,3,5 - triphenyl - 2H tetrazolium chloride was dissolved in 2 ml of DOP and dispersed in the same way as in Sample P to give Sample Q. Further a to methanol solution of 1.8 g of 2,3,5 - triphenyl - 2H - tetrazolium chloride was added to the silver halide emulsion to give Sample R. These samples were treated in the same way as in Example 1. The results thus obtained were shown in Table 5. TABLE 5 Specific Situation An Average Sample Sensitivity of Dots Grain Size (,u) P 100 0.4 Q 95 O 0.4 R 85 Q3 Table 5 shows that the non-diffusible tetrazolium compound of this invention has a high sensitivity compared with the diffusible compound and an excellent dot quality. WHAT WE CLAIM IS:

1. A light-sensitive silver halide photographic material comprising a support and a photographic element layer including a silver halide emulsion layer which photographic element layer comprises a tetrazolium compound dispersed in a nondiffusible state as herein defined, the average grain size of the compound being not more than 1.0 N as herein defined.

2. A light-sensitive silver halide photographic material according to Claim 1 wherein the photographic element layer is a silver halide emulsion layer.

3. A light-sensitive silver halide photographic material according to Claim 1 wherein hydrophilic colloidal protecting layer containing gelatin is located as an outermost layer.

4. A light-sensitive silver halide photographic material according to Claim 1 wherein the compound is represented by following formula [I], [II] or [III]:

wherein R1, R3, R4, R,, Ras R9, R10 and R11 each represent hydrogen, nitro or mercapto, or an amino group, an alkyl group, an alkenyl group, an aryl group or a heterocyclic group; R2, R6 and R7 each represent hydrogen, hydroxyl, carboxyl, mercapto or nitro, or an amino group, an alkyl group, an alkenyl group, an alkenyl group, an aryl group, a heterocyclic group or an alkoxycarbonyl group; D represents arylene; E represents alkylene, alkenylene, arylene or aralkylene; Xe represents an anion; and n represents an integer 1 or 2 provided that the compound forms a molecular inner salt when n is 1.

5. A light-sensitive silver halide photographic material according to Claim 4 wherein the compound is of formula [I].

6. A light-sensitive silver halide photographic material according to Claim 5 wherein R1, R2 and R3 each represent an aryl group.

7. A light-sensitive silver halide photographic material according to Claim 6 wherein R1, R2 and R3 each represents a phenyl group.

8. A light-sensitive silver halide photographic material according to Claim 4, wherein XO represents a halogen ion, a sulfate ion, a nitrate ion, a perchlorate ion, an alkylarylsulfonate ion, a higher alkylsulfate ion, a dialkylsulfosuccinate ion, a polyetheralcoholsulfate ion, a higher alkyl carboxylic ion or an anionic polymer.

9. A light-sensitive silver halide photographic material according to Claim 8 wherein XO represents an alkylarylsulfonate ion, a higher alkylsulfate ion, a dialkylsulfosuccinate ion, a polyetheralcoholsulfate ion, a higher alkylcarboxylic ion or an anionic polymer.

10. A light-sensitive silver halide photographic material according to Claim 4 wherein the cationic moieties of the compound is: 2 - (benzothiazol - 2 - yl) - 3 - phenyl - 5 - dodecyl - 2H - tetrazolium 2,3 - diphenyl - 5 - (4 - t - octyloxyphenyl) - 2H - tetrazolium 2,3,5 - triphenyl - 2H - tetrazolium 2,3,5 - tri(p - carboxyethylphenyl) - 2H - tetrazolium 2 - (benzothiazol - 2 - yl) - 3 - phenyl - 5 - (o - chlorophenyl) - 2H tetrazolium 2,3 - diphenyl - 2H - tetrazolium 2,3 - diphenyl - 5 - methyl - 2H - tetrazolium 3 - (p - hydroxyphenyl) - 5 - methyl - 2 - phenyl - 2H - tetrazolium 2,3 - diphenyl - 5 - ethyl - 2H - tetrazolium 2,3 - diphenyl - 5 - n - hexyl - 211 - tetrazolium 5 - cyano - 2,3 - diphenyl - 211 tetrazolium 2 - (benzothiazol - 2 - yl) - 5 - phenyl - 3 - (4 - tolyl) - 2H - tetrazolium 2 - (benzothiazol - 2 - yl) - 5 - (4 - chlorophenyl) - 3 - (4 - nitrophenyl) 2H - tetrazolium 5 - ethoxycarbonyl - 2,3 - di(3 - nitrophenyl) - 2H - tetrazolium 5 - acetyl - 2,3 - di(p - ethoxyphenyl) - 2H - tetrazolium 2,5 - diphenyl - 3 - (p - tolyl) - 2H - tetrazolium 2,5 - diphenyl - 3 - (p - iodophenyl) - 2H - tetrazolium 2,3 - diphenyl - 5 - (p - diphenyl) - 2H - tetrazolium 5 - (p - bromophenyl) - 2 - phenyl - 3 - (2,4,6 - trichlorophenyl) - 2H tetrazolium 3 - (p - hydroxyphenyl) - 5 - (p - nitrophenyl) - 2 - phenyl - 2H tetrazolium 5 - (3,4 - dimethoxyphenyl)- 3 - (2 - ethoxyphenyl) - 2 - (4 methoxyphenyl) - 2H - tetrazolium 5 - (4 - cyanophenyl) - 2,3 - diphenyl - 2H - tetrazolium 3 - (p - acetamidophenyl) - 2,5 - diphenyl - 2H - tetrazolium 5 - acetyl - 2,3 - diphenyl - 2H - tetrazolium 5 - (fur - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium 5 - (thien - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium 2,3 - diphenyl - 5 - (pyrid - 4 - yl) - 2H - tetrazolium 2,3 - diphenyl - 5 - (quinol - 2 - yl) - 2H - tetrazolium 2,3 - diphenyl - 5 - (benzoxazol - 2 - yl) - 2H - tetrazolium 2,3 - diphenyl - 5 - nitro - 2H - tetrazolium 2,2',3,3' - tetraphenyl - 5,5'-1,4 - butylene - di(2H - tetrazolium) 2,2',3,3' - tetraphenyl - 5,5' - p - phenylene - di(2H - tetrazolium) 2 - (4,5 - dimethylthiazol - 2 - yl) - 3,5 - diphenyl - 2H - tetrazolium 3,5 - diphenyl - 2 - (triazin - 2 - yl) - 2H - tetrazolium 2 - (benzothiazol - 2 - yl) - 3 - (4 - methoxyphenyl) - 5 - phenyl - 2H tetrazolium or 2 - p - iodophenyl - 3 - p - nitrophenyl - 5 - phenyl - 2H - tetrazolium.

11. A light-sensitive silver halide photographic material according to Claim 4 wherein the salt of tetrazolium compound is: 2 - (benzothiazol - 2 - yl) - 3 - phenyl - 5 - dodecyl - 2H - tetrazolium stearate 2,3 - diphenyl - 5 - (4 - t - octyloxyphenyl) - 2H - tetrazolium laurate 2,3,5 - triphenyl - 2H - tetrazolium di - 2 - ethylhexylsulfosuccinate 2,3,5 - tri(p - carboxyethylphenyl) - 2H - tetrazolium stearate 2 - (benzothiazol - 2 - yl) - 3 - phenyl - 5 - (o - chlorophenyl)laurate - 2H tetrazolium p - dodecylbenzenesulfonate 2,3 - diphenyl - 2H - tetrazolium di - 2 - ethylhexylsulfosuccinate 2,3 - diphenyl - 5 - methyl - 2H - tetrazolium p - octylbenzenesulfonate 3 - (p - hydroxyphenyl) - 5 - methyl - 2 - phenyl - 2H - tetrazolium stearate 2,3 - diphenyl - 5 - ethyl - 2H - tetrazolium di - 3 - methylnonylsulfonate 2,3 - diphenyl - 5 - n - hexyl - 2H - tetrazolium p octadecylbenzenesulfonate 5 - cyano - 2,3 - diphenyl - 2H - tetrazolium di - 2 ethylhexylsulfosuccinate 2 - (benzothiazol - 2 - yl) - 5 - phenyl - 3 - (4 - tolyl) - 211 - tetrazolium p dodecylbenzenesulfonate 2 - (benzothiazol - 2 - yl) - 5 - (4 - chlorophenyl) - 3 - (4 - nitrophenyl) 2H - tetrazolium di - isopropylnaphthalenesulfonate 5 - ethoxycarbonyl - 2,3 - di(3 - nitrophenyl) - 2H - tetrazolium stearate 5 - acetyl - 2,3 - di(p - ethoxyphenyl) - 2H - tetrazolium laurate 2,5 - diphenyl - 3 - (p - tolyl) - 2H - tetrazolium stearate 2,5 - diphenyl - 3 - (p - iodophenyl) - 2H - tetrazolium laurate 2,3 - diphenyl - 5 - (p - diphenyl) - 2H - tetrazolium di isopropylnaphthalenesulfonate 5 - (p - bromophenyl) - 2 - phenyl - 3 - (2,4,6 - trichlorophenyl) - 2H tetrazolium di - isopropylnaphthalene - di - sulfonate 3 - (p - hydroxyphenyl) - 5 - (p - nitrophenyl) - 2 - phenyl - 2H tetrazolium p - dodecylbenzenesulfonate 5 - (3,4 - dimethoxyphenyl) - 3 - (2 - ethoxyphenyl) - 2 - (4 methoxyphenyl) - 2H - tetrazolium di - 2 - ethylhexylsulfosuccinate 5 - (4 - cyanophenyl) - 2,3 - diphenyl - 211 - tetrazolium laurate 3 - (p - acetamidophenyl) - 2,5 - diphenyl - 2H - tetrazolium stearate 5 - acetyl - 2,3 - diphenyl - 211 - tetrazolium p - octadecylbenzenesulfonate 5 - (fur - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium di - 2 ethylhexylsulfonate 5 - (thien - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium stearate 2,3 - diphenyl - 5 - (pyrid - 4 - yl) - 2H - tetrazolium laurate 2,3 - diphenyl - 5 - (quinol - 2 - yl) - 2H - tetrazolium stearate 2,3 - diphenyl - 5 - (benzoxazol - 2 - yl) - 2H - tetrazolium laurate 2,3 - diphenyl - 5 - nitro - 2H - tetrazolium di isopropylnaphthalenesulfonate 2,2',3,3' - tetraphenyl - 5,5',1,4 - butylene - di(2H - tetrazolium) di - 3 propylnonylsulfonate 2,2',3,3' - tetraphenyl - 5,5' - p - phenylene - di(2H - tetrazolium) p dodecylbenzenesulfonate 2 - (4,5 - dimethylthiazol - 2 - yl) - 3,5 - diphenyl - 2H - tetrazolium stearate 3,5 - diphenyl - 2 - (triazin - 2 - yl) - 2H - tetrazolium laurate 2 - (benzothiazol - 2 - yl) - 3 - (4 - methoxyphenyl) - 5 - phenyl - 2H tetrazolium p - tolylsulfonate 2 - p - iodophenyl - 3 - p - nitrophenyl - 5 - phenyl - 2H - tetrazolium di isopropylnaphthalene - di - sulfonate or 2,3,5 - triphenyl - 2H - tetrazolium di - isopropylnaphthalene di - sulfonate.

12. A light-sensitive silver halide photographic material according to any preceding claim, wherein an average size of silver halide grain is 0.1-1.0 and at least 75% of the whole grain is 0.6-1.4 times of the average size.

13. A light-sensitive silver halide photographic material according to Claim 3 wherein the thickness of the protective layer is 0.1-10 ,u.

14. A light-sensitive silver halide photographic material according to Claim 14 wherein the thickness of the protective layer is 0.8-2.0 M

15. A light-sensitive silver halide photographic material according to any preceding claim, wherein the amount of the salt of tetrazolium compound is 0.0001-10 mole/mol of silver halide.

16. A light-sensitive silver halide photographic material according to Claim 15, wherein the amount is 0.001-1 mole/mole of silver halide.

17. A light-sensitive silver halide photographic material according to Claim 1 and substantially as hereinbefore described with reference to any of Examples 1 to 7.