GB1589594A

GB1589594A - Light-sensitive silver halide photographic material and method of processing thereof

Info

Publication number: GB1589594A
Application number: GB3145177A
Authority: GB
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 1976-07-31
Filing date: 1977-07-27
Publication date: 1981-05-13
Also published as: JPS5317720A; CA1115584A; JPS5917818B2; AU2735377A; FR2360911A1; AU499945B2; DE2734335A1; DE2734335C2; SE7708670L

Description

(54) LIGHT-SENSITIVE SILVER HALIDE PHOTOGRAPHIC MATERIAL AND METHOD OF PROCESSING THEREOF (71) We, KONISHIROKU PHOTO INDUSTRY CO. LTD., A Corporation organized and existing under the laws of Japan, of 1--10, 3-chome, Nihonbashimuromachi, 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 and the processing method therefor. 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, and to the processing method therefore.

More particularly, it relates to a 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 line-image on a lith (printing) light-sensitive silver halide material or a copying light-sensitive material, as well as to the processing method therefor.

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 line-or dot-image by treating, with an alkaline hydroquinones developing solution containing sulfite ions in a very low concentration, a light-sensitive material which comprises a silver halide emulsion containing silver chloride in a high content (at least more than 50 mole %) and further containing silver iodide less than 5 mole %, the grains of which emulsion being minute (average grain size; ca. 0.3 ,u), uniform in size and shape, and the grain size distribution thereof being narrow. The abovementioned 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 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 light-sensitive 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 and makes the dot quality worse.

There has heretofore been employed the lith type light-sensitive material also for the reproduction of a line image. For the same reason, however, there have been obtained images having at best the y-value of 5-6 of the characteristic curve, which value is lower than 7-9 required for forming the desirable line-image, if the standard black and white developing solution is employed. 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 developing solution is very poor in storability because of the low concentration of the sulfite. 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 l-phenyl-3-pyrazolidone/hydroquinone developing solution which has excellent storability, is recommended for processing the light-sensitive materials. However there has been known no method capable of obtaining a dot image with a good dot quality, by using such a developing solution.

This invention provides a light-sensitive silver halide photographic material to be treated with a hydroquinones containing developing solution which comprises a support, at least one hydrophilic colloidal layer coated thereon which contains silver halide grains having a number average grain size of 0.1 to 0.5 ,t4, at least 80% of which grains being within a range of 0.7 to 1.3 times the average grain size, and the silver halide being silver chlorobromide or chloroiodobromide containing at least 50 mole% of silver chloride, a sensitizing dye, and a tetrazolium compound having the formula (I), (II) or (III):

wherein R1, R3, R4, R5, Re, Rg, Rao and R11 each represents aryl, substituted aryl, or a heterocyclic group; R2, Re and R7 each represents aryl, substituted aryl, a heterocyclic group, alkyl, substituted alkyl, hydroxy, carboxyl, or a salt thereof, amino, mercapto, cyano, acyl, nitro or hydrogen; D represents a divalent aromatic group; E represents alkylene, arylene, or aralkylene; said heterocyclic group being fur-2-yl, thien-2-yl, quinol-2-yl, benzoxazol-2-yl, thiadiazolyl, benzothiadiazolyl, oxazolyl, pyrimidinyl, pyridyl or 2,5-dimethyl-thiadiazolyl, X is an anion; and n is I or 2, provided that the compound forms an intramolecular salt when n is 1.

This invention also provides a method of processing these photographic materials, after image-wise exposure to light, by contacting the resulting exposed photographic material with a hydroquinone-containing developing solution.

In accordance with the invention a superior line- or dot-image can be formed, without employing infectious development.

According to a preferred embodiment of the invention, there is obtained a dotimage (half tone image) with a superior development stability and a superior dot quality by developing the light-sensitive silver halide photographic material after image-wise exposure through a contact screen, with a Metol/hydroquinone developing solution (hereinafter referred to as the MQ developing solution) or with a l-phenyl-3-pyrazolidone-hydroquinone developing solution, (hereinafter referred to as the PQ developing solution) which are widely used black and white developing solutions.

It can not be expected from heretofore known techniques that high contrast line- or dot-images could be obtained without employing the infectious developing solution.

As explained above, the tetrazolium compounds include non-diffusible and diffusible ones. The term "non-diffusible tetrazolium compound" means a compound which does not dissolve from the light-sensitive material into the developing solution during the development. In other words, the compound preferably does not dissolve in a concentration of more than 2%, when a gelatin layer containing the compound is dipped for 10 minutes in an aqueous solution at 20A0 C having the same ion strength and pH-value as those of the developing solution.

The representative tetrazolium compound employed in the invention have the general formulae:

In the above formulae, R1, R, R4, R5, R8, R9, R10 and R11 each represents an aryl or substituted aryl group (e.g. phenyl, tolyl, hydroxyphenyl, carboxyphenyl, aminophenyl or mercaptophenyl, carboxyethyl, nitrophenyl, ethoxyphenyl, iodophenyl, methoxyphenyl, cyanophenyl, acetoamidophenyl, a-naphthyl, p- naphthyl, hydroxynaphthyl, carboxynaphthyl or aminonaphthyl); or a heterocyclic group (as defined above). The groups can advantageously contain an electron sharing group capable of forming a metal chelate or a complex such as primary, secondary, tertiary amino, oxime, thioether, keto, thioketo, hydroxyl, mercapto, carboxyl, sulfo, phospho, or alkoxyl, R2, R5 and R, each represents an aryl or substituted acyl group (such as a phenyl group or naphthyl group), a heterocyclic group (as defined above), an alkyl or substituted alkyl group (e.g. methyl, ethyl, propyl, butyl, mercaptomethyl or mercaptoethyl or a carboxyalkyl group such as methoxycarbonyl or ethoxycarbonyl), hydroxyl, carboxyl or a salt thereof, an amino group (e.g. amino, ethylamino or anilino), mercapto cyano acyl, nitro or hydrogen; D represents a divalent aromatic group; E represents an alkylene group, an arylene group or an aralkylene group; X is an anion; and n is I or 2, provided that the compound forms an intramolecular salt when n is 1.

In the above formulae, the divalent aromatic group for E is preferably an arylene group (e.g. phenylene, alkoxy-substituted phenylene such as methoxysubstituted phenylene, naphthylene or diphenylene) or a divalent aromatic heterocyclic group.

The following are typical examples of the cationic moieties of the tetrazolium compounds represented by the formula 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 - (Benzothiozol - 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 - diphenyl) - 2H - tetrazolium (19) 5 - (P - Bromophenyl) - 2 - phenyl - 3 - (2,4,6 - trichlorphenyl) - 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 - 211 - 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 - (2H - 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) 2,5 - Diphenyl - 3 - cu - naphthyl - 2H - tetrazolium (37) 3,3' (3,3' - Dimethoxy - 4,4' - diphenylene) - 2,2',5,5' - tetraphenyl - di (2H - tetrazolium) The anion X can be e.g. a halogen ion, a thiosulfate anion, a sulfate anion, a thiocyanate anion, an alkylsulfate anion, a nitrate anion, an acetate anion, a lower alkyl benzensulfonate anion for the diffusible tetrazolium compound and higher alkylbenzene-sulfonate anion such as p-dodecylbenzenesulfonate anion, a higher alkylsulfate anion such as laurylsulfate anion, a dialkylsulfosuccinate anion such as di-2-ethylhexylsulfosuccinate anion, a polyether alcohol sulfate anion such as cetylpolyethenoxysulfate anion, a higher fatty acid anion such as stearic acid anion, or a polymer having acid radicals such as polyacrylate anion for the non-diffusible tetrazolium compound.

Most typical examples of the compounds of the invention are as follows: [1] Diffusible tetrazolium compound (1) 2,3,5 - Triphenyl - 2H - tetrazolium chloride (2) 2,3,5 - Tri(P - carboxyethylphenyl) - 2H - tetrazolium iodide (3) 2 - (Benzothiazol - 2 - yl) - 3 - phenyl - 5 - (o - chlorophenyl)- 2H tetrazolium bromide (4) 2,3 - Diphenyl - 2H - tetrazolium thiosulfate (5) 2,3 - Diphenyl - 5 - methyl - 2H - tetrazolium chloride (6) 3 - (p - Hydroxyphenyl) - 5 - methyl - 2 - phenyl - 2H - tetrazolium sulfate (7) 2,3 - Diphenyl - 5 - ethyl - 211 - tetrazolium chloride (8) 2,3 - Diphenyl - 5 - n - hexyl - 2H - tetrazolium chloride (9) 5 - Cyano - 2,3 - diphenyl - 2H - tetrazolium thiocyanate (10) 2 - (Benzothiazol - 2 - yl) - 5 - phenyl - 3 - (4 - tolyl) - 2H - tetrazolium chloride (Il) 2 - (Benzothiazol - 2 - yl) - 5 - (4 - chlorophenyl) - 3 - (4 - nitrophenyl) 2H - tetrazolium chloride (12) 5 - Ethoxycarbonyl - 2,3 - di - (3 - nitrophenyl) - 2H - tetrazolium bromide (13) 5 - Acetyl - 2,3 - di(p - ethoxyphenyl) - 2H - tetrazolium chloride (14) 2,5 - Diphenyl - 3 - (p - tolyl) - 2H - tetrazolium methylsulfate (15) 2,5 - Diphenyl - 3 - (p - iodophenyl) - 2H - tetrazolium chloride (16) 2,3 - Diphenyl - 5 - (p - diphenyl) - 2H - tetrazolium chloride (17) 5 - (p - Bromophenyl) - 2 - phenyl - 3 - (2,4,6-trichlorophenyl) - 2H tetrazolium chloride (18)3 - (p - Hydroxyphenyl) - 5 - methyl - 2 - phenyl - 2H - tetrazolium chloride (19) 5 - (3,4 - Dimethoxyphenyl) - 3 - (2 - ethoxyphenyl) - 2 - (4 - methoxyphenyl) - 2H - tetrazolium chloride (20) 5 - (4 - Cyanophenyl) - 2,3 - diphenyl - 2H - tetrazolium chloride (21) 3 - (p - Acetamidophenyl) - 2,5 - diphenyl - 2H - tetrazolium chloride (22) 5 - Acetyl - 2,3 - diphenyl - 2H - tetrazolium chloride (23) 5 - (Fur - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium chloride (24)5 - (Thien - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium chloride (25) 2,3 - Diphenyl - 5 - (pyrid - 4 - yl) - 2H - tetrazolium nitrate (26) 2,3 - Diphenyl - 5 - (quinol - 2 - yl) - 2H - tetrazolium chloride (27) 2,3 - Diphenyl - 5 - (benzoxazol - 2 - yl) - 2H - tetrazolium chloride (28) 2,3 - Diphenyl - 5 - nitro - 2H - tetrazolium methylsulfate (29) 2,2',3,3' - Tetraphenyl - 5,5' - 1,4 - butylene - di - (2H - tetrazolium chloride) (30) 2,2'.3,3' - Tetraphenyl - 5,5' - p - phenylene - di - (2H - tetrazolium chloride) (31) 2 - (4,5 - Dimethylthiazol - 2 - yl) - 3,5 - diphenyl - 2H - tetrazolium chloride (32) 3,5 - Diphenyl - 2 - (triazin - 2 - yl) - 2H - tetrazolium sulfate (33) 2 - (Benzothiazol - 2 - yl) - 3 - (4 - methoxyphenyl - 5 - phenyl - 2H tetrazolium chloride) (24) 2,5 - Diphenyl - 3 - a - naphthyl - 2H - tetrazolium chloride (35) 3,3' (3,3' - Dimethoxy - 4,4' - diphenylene) - 2,2',5,5' - tetraphenyl - di (2H - tetrazolium chloride) (36) 5 - (3 - Methoxyphenyl) - 3 - (3 - trifluoromethylphenyl) - 2 - phenyl - 2H tetrazolium acetate [2] Non diffusible tetrazolium compound (37) 2 - (Benzothiazol - 2 - yl - 3 - phenyl - 5 - dodecyl - 2H - tetrazolium bromide (38) 2,3 - Diphenyl - 5 - (4 - t - octyloxyphenyl) - 2H - tetrazolium chloride (39) 2,3,5 - Triphenyl - 2H - tetrazolium diethylhexylsuccinate sulfonate (40) 2,3,5-Tri(p - carboxyethylphenyl) - 2H - tetrazolium p - dodecylbenzenesulfonate (41) 2 - (Benzothiazol - 2 - yl) - 3 - phenyl - 5 - (o - chlorophenyl) - 2H tetrazolium diethylhexylsuccinate sulfonate (42) 2,3 - Diphenyl - 2H - tetrazolium p - octylbenzenesulfonate (43) 2,3 - Diphenyl - 5 - methyl - 2H - tetrazolium laurylsulfate (44) 3 - (p - Hydroxyphenyl - 5 - methyl - 2 - phenyl - 2H - tetrazolium isopropylnaphthalenesulfonate (45) 2,3 - Diphenyl - 5 - ethyl - 2H - tetrazolium diethylhexylsuccinate sulfonate (46) 2,3 - Diphenyl - 5 - n - hexyl - 2H - tetrazolium cetylpolyethenoxysulfate (47) 5 - Cyano - 2,3 - diphenyl - 2H - tetrazolium polyacrylate (48) 2 - (Benzothiazol - 2 - yl) - 5 - phenyl - 3 - (4 - tolyl) - 2H - tetrazolium diethylhexylsuccinate sulfonate (49) 2 - (Benzothiazol - 2 - yl) - 5 - (4 - chlorophenyl) - 3 - (4 - nitrophenyl) 2H - tetrazolium diethylhexylsuccinate sulfonate (50) 5 - Ethoxycarbonyl - 2,3 - di(3 - nitrophenyl) - 2H - tetrazolium diethylhexylsuccinate sulfonate (51) 5 - Acetyl - 2,3 - di(p - ethoxyphenyl) - 2H - tetrazolium diethylhexylsuccinate sulfonate (52) 2,5 - Diphenyl - 3 - (p - tolyl) - 211 - tetrazolium p - octylbenzenesulfonate (53) 2,5 - Diphenyl - 3 - (p - iodophenyl) - 2H - tetrazolium p - octylbenzenesulfonate (54) 2,3 - Diphenyl - 5 - (p - diphenyl) - 2H - tetrazolium p - octylbenzenesulfonate (55)5 - (p - Bromophenyl) - 2 - phenyl - 3 - (2,4,6 - trichlorophenyl) - 2H - tetrazolium isopropylnaphthalenesulfonate (56) 3 - (p - Hydroxyphenyl) - 5 - (p - nitrophenyl) - 2 - phenyl - 2H tetrazolium diethylhexylsuccinate sulfonate (57)5 - (3,4, - Dimethoxyphenyl) - 3 - (2 - ethoxyphenyl) - 2 - (4 - methoxyphenyl) - 2H - tetrazolium diethylhexylsuccinate sulfonate (58) 5 - (4 - Cyanophenyl) - 2,3 - diphenyl - 2H - tetrazolium diethylhexylsuccinate sulfonate (59)3 - (p - Acetamidophenyl) - 2,5 - diphenyl - 2H - tetrazolium laurylsulfate (60) 5 - Acetyl - 2,3-diphenyl - 2H - tetrazolium diethylhexylsuccinate sulfonate (61) 5 - (Fur - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium diethylhexylsuccinate sulfonate (62)5 - (Thien - 2 - yl) - 2,3 - diphenyl - 2H - tetrazolium diethylhexylsuccinate sulfonate (63) 2,3 - Diphenyl - 5 - (pyrid - 4 - yl) - 2H - tetrazolium diethylhexylsuccinate sulfonate (64) 2,3 - Diphenyl- 5 - (quinol - 2- yl) - 2H - tetrazolium diethylhexylsuccinate sulfonate (65) 2,3 - Diphenyl - 5 - (benzoxazol - 2 - yl) - 2H - tetrazolium diethylhexylsuccinate sulfonate (66) 2,4 - Diphenyl - 5 - nitro - 2H - tetrazolium polyacrylate (67) 2,2',3,3' - Tetraphenyl - 5,5' - 1,4-butylene - di- (2H - tetrazolium) laurylsulfate (68) 2,2',3,3' - Tetraphenyl- 5,5' - p - phenylene - di - (2H - tetrazolium) cetylpolyethenoxysulfate (69) 2 - (4.5 - Dimethylthiazol - 2 - yl) - 3,5-diphenyl - 2H - tetrazolium polyacrylate (70) 3,5 - Diphenyl - 2 - (triazin - 2 - yl) - 2H - tetrazolium stearate (71) 2 - (Benzothiazol - 2 - yl) - 3 - (4 - methoxyphenyl) - 5 - phenyl - 2H - tetrazolium di - ethylhexylsulfosuccinate (72) 2,5 - Diphenyl - 3 - a - naphthyl - 2H - tetrazolium dodecylsulfate (73) 3,3' - (3,3' - Dimethoxy. - 4,4' - diphenylene) - 2,2'5,5' - tetraphenyl - di - (2' tetrazolium polyacrylate) (74) 5 - (3 - Methyloxyphenyl) - 3 - (3 - trifluoromethylphenyl) - 2 - phenyl tetrazolium isopropylnaphthalenesulfonate (75) 2,3,5 - Triphenyl - 2H - tetrazolium isopropylnaphthalenesulfonate The non-diffusible or diffusible tetrazolium compounds according to the invention are thus synthesized by an optional selection of the anionic and cationic moieties. The non-diffusible compounds, e.g. 2,3,5 - triphenyl - 2H - tetrazolium dioctyl-succinatesulfonate may disperse into a gelatin solution by mixing a corresponding soluble tetrazolium salt with the gelatin solution and then an anion that will provide a non-diffusible tetrazolium compound is admixed thereto thereby to obtain the gelatin solution with a dispersed non-diffusible, tetrazolium compound as specifically mentioned in working Examples set forth later.

Alternatively, crystals of the non-diffusible tetrazolium compound synthesized as such may be dissolved in a suitable solvent such as dimethylsulfoxide and then dispersed in the gelatin solution.

When the dispersion is not sufficiently homogeneous, good results may be obtained by exposing the emulsion dispersion to ultrasonic waves or by use of a suitable homogenizer such as a Manton-Gaulin homogenizer.

As mentioned above, the tetrazolium compounds of this invention may be used both in diffusible and non-diffusible forms, when the silver halide of this invention is employed. However, the higher contrast image may be obtained by employing the nondiffusible tetrazolium compounds. Accordingly, it is advantageous to employ the non-diffusible tetrazolium compound when an especially superior dot quality is required.

On the other hand, the use of too much high contrast light-sensitive material sometimes brings about not sufficient reproduction of the line-image, particularly those of fine letters and lines. In this case, an image with more superior quality may be obtained by the use of the diffusible tetrazolium compounds.

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-menfioned tetrazolium compounds 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.

The sensitizing dyes used in this invention mean those which can extend a sensitive wave length range of the silver halide outside of its inherent sensitive wave length. Sensitizing dyes used for this invention cover those such as cyanines, merocyanines, herhicy nines, oxonols, hemioxonols or mixed merocyanines. Such dyes are described in e.g. "The cyanine dye and related compounds" by F. M.

Hamer and "The Theory of Photographic Process" Third edition by C. E. Kenneth Mees and T. H. James.

Preferred sensitizing dyes of this invention may be concretely expressed by the general formula [I]-[VlI];

In which R21, R22 and R23 each represents an alkyl or substituted allyl group (e.g. methyl, ethyl propyl, butyl, chloroethyl, hydroxyethyl, methoxyethyl, acetoxyethyl, carboxymethyl, carboxyethyl, ethoxycarbonylmethyl, sulfoethyl, sulfopropyl, sulfobutyl, phydroxy-y-sulfopropyl, sulfa'icpropyl, allyl, or benzyl) or an aryl or substituted aryl group (e.g. phenyl, carboxyphenyl or sulfophenyl). L1, L2 and L3 each represents a methine or substituted methine group (e.g. --CH=, --C(CH,)=, --C(C,H,)=, --C(CH,COOH)=,

-C (C6H5)= or --C(C,H,COOH)=). Z1,Z2 and Z3 each represents an atom or atom groups necessary for forming a 5 to 6 membered heterocyclic ring (e.g. a thiazoline, oxazoline, selenazoline, thiazole, selenazole, oxazole, benzothiazole, benzooxabole, benzoquinazole, benzoimidazole, 3,3-dialkyl-indolenine, naphthothiazole, naphthooxazole, paththoselenazole, thienothiazole, 2-pyridine, 4pyridine, 2-quinoline or 4-quinoline nucleus). P and Q each represents cyano, -COOR4, -COR4 or -SO2R4 in which R4 represents an alkyl group; further Q1 and Q2 each represent an atomic group necessary for forming a substituted or unsubstituted thiooxazolone ring, a pyrazolone ring, an oxindole ring, a barbituric acid, a 2-thiobarbituric acid, a 2,4-oxazolidinedione ring, a 2,4-thiazolidinedione ring, a 2,4-imidazolidinedione ring, a 2-thio-2,4-oxazolidinedione ring, a 2-thio-2,4-thiazolidinedione ring, a 2-thio-2,4-selenazolidinedione ring, a 2-thio-2,5thiazolidinedione ring, a 2-thiohydantoin ring, a 4-oxazolinone ring, a 4-thiazolinone ring or a 4-imidazoline ring, Y represents hydrogen, amino, alkylamino preferably having 1 to 4 carbon atoms (e.g. ethylamino), dialkylamino preferably having 2 to 8 carbon atoms (e.g. dimethylamino), halogen (e.g. chlorine or bromine) or an alkyl group preferably having 1 to 4 carbon atoms (e.g. methyl) m, and m2 each represent zero or 1; n, and n2 each represent 0, 1 or 2; X represents an acid anion (e.g. Cls, BrO, IO, CIO4O,

CH3SO49 or C2HsSO48), 1 represents I or 2 and an intramolecular salt is formed when I represents 1.

Typical sensitizing dyes having the above general formulae according to this invention will be exemplified below but this is not intended to limit thes dyes:

These compounds can readily be synthesized by the methods described in e.g.

U.S. Patents 2,213,995, 3,711,288, 2,503,776, 3,576,641, 2,945,736, 3,625,698, etc.

These sensitizing dyes used according to this invention may be incorporated into a hydrophilic colloid containing the silver halide and the tetrazolium compound by dissolving them in water or an organic solvent such as methanol and ethanol, which is miscible with water in any ratio and they can be used in single or in combination of two or more.

The incorporation of the sensitizing dyes into said hydrophilic colloid may be any time during the preparation of the silver halide emulsion, but is preferred to be generally after the completion of the second ripening.

The sensitizing dye can be used in an amount of 10 mg to 1 g, preferably 30 to 300 mg, per one mole of silver halide.

The light-sensitive silver halide photographic material of this invention, in which the sensitizing dye is incorporated, can not only show an excellent stability during development but also can be sensitized in any preferred spectrum range. In addition, a super sensitization can be expected by use of a combination of two or more sensitizing dyes in general.

The silver halide used according to the invention is silver chloroiodobromide or chlorobromide having a number average grain size of 0.1-0.5 y and at least 80% grains of the total grains being within a range of 0.7-1.3 times the average grain size.

The silver halide having the above-mentioned average grain size and the distribution thereof may be prepared by any known method described, e.g. in U.S.

Patents 2,592,250, 3,276,877, 3,317,322, 2,222,264, 3,320,069 and 3,206,313 and in Journal of Photographic Science 12(5), 242-251(1964). Silver halides prepared by other methods may also be employed in admixture.

The silver halide emulsion used according to the invention may be sensitized with various kinds of chemical sensitizers. As the sensitizer, there can be mentioned, for example, activated gelatin, sulfur senstizers (e.g. sodium thiosulfate, aryl thiocarbamide, thiourea or aryl isocyanate, etc.), selenium sensitizers (e.g.

N,N-dimethylserenourea or selenourea, etc.), reducing sensitizers (e.g. triethvlene tetramine or stannie chloride, etc.) and various noble metal sensitizers represented by potassium chloroaurite, potassium auriothiocyanate, potassium chloroaurate, 2aurosulfobenzothiazole methylchloride, ammonium chloropalladate, potassium chloroplatinate and sodium chloropalladite. The sensitizer may be employed alone, or mixed together. Ammonium thiocyanate may be auxiliarily employed when a gold sensitizer is employed.

The silver halide emulsion may preferably be stabilized with 5,6 trimethylene - 7 - hydroxy - s - triazolo(l,5 - a)pyrimidine, 5,6 - tetra methylene - 7 - hydroxy - s - triazolo - (1,5 - a)pyrimidine, 5 - methyl - 7 - hydroxy s - triazolo - (1,5 - a)pyrimidine, 7 - hydroxy - s - triazolo(l,5 -a)py described in, e.g. British Patent 523,661, U.S. Patents 3,847,620, 3,655,389 and 3,341,332, gelatin derivatives such as phenylcarbamyl-, acylated- or phthalatedgelatin described in, e.g U.S. Patents 2,614,928 and 2,525,753, 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, described in e.g. U.S. Patents 2.548,520 and 2,831,767.

Such hydrophilic colloids may also be applied to a layer containing no silver halide, e.g. an antihalation layer, a protective layer or an intermediate layer.

The light-sensitive silver halide material of the invention may be prepared by coating the above-mentioned layer containing the silver halide, the sensitizing dye and the tetrazolium compound of the invention on a suitable photographic support.

As representative supports employed in the invention are mentioned, e.g. a baryta paper, a polyethylene-coated paper, 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, or a polystyrene film. The supports are optionally selected depending on the purpose for which the light-sensitive photographic material is used.

As mentioned above, the light-sesitive 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 sensitizing dye and a tetrazolium compound.

It is preferable in the light-sensitive material of the invention that a protective layer having a suitable thickness is coated. The protective layer is advantageously a gelatin layer, the thickness of which is preferably 0.1-10 , more preferably 0.8-2.0 M The presence of the protective layer may act effectively on the stability of the image quality and of the developing process in this invention. This is presumed because, the protective layer may have a function to control adequately the infiltration rate of the hydroquinone/Metol or l-phenyl-3-pyrazolidone from the processing solution into the light-sensitive material, or the diffusion rate of the tetrazolium compound within the light-sensitive material of therefrom to the processing solution. This effect is remarkable when the tetrazolium compound is employed according to the invention. The effect is not so remarkable when other oxidizing agents than the tetrazolium compound, described in, e.g. Japanese Patent Provisional Publication No. 52-18317 (1977) are employed.

Various kinds of photographic additives may optionally be added to the abovementioned 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, a image stabilizer, an ultraviolet absorber, an anthistaining 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, or a matting agent.

Among the additives mentioned above, the following may particularly and preferably be employed: viscosity-increasing agents and plasticizers, described in U.S. Patents 2,960,404 and 3,767,410, 3,659,956 and 3,692,753, e.g. a styrene/sodium maleate copolymer and dextran sulfate; hardening agents of an aldehyde, epoxy, ethyleneimine, active halogen, vinylsulfone, isocyanate, sulfonic acid ester, carbodiimide, mucochloric acid or acryloyls, image stabilizers, e.g. 6,6'butylidene-bis(2-t-butyl-4-methylphenyl) and 4,4'-methylene-bis(2,6-di-t-butylphenol), ultraviolet absorbers, described in, e.g. U.S. Patent 3,253,921, British Patent 1,309,349, U.S. Patents 3,533,794 and 3,707,375 and British Patent 1,287,770, particularly 2 - (2 - hydroxy - 5 - t - butylphenyl)benzotriazole, 2 - (2 - hydroxy 3,5-di - t - bytylphenyl)benzotriazole, 2 - (2 - hydroxy - 3 - t - butyl - 5 butylphenyl) - 5 - chlorobenzotriazole and 2 - (2 - hydroxy - 3,5 - di - t butylphenyl) - 5 - chlorobenzotriazole; surface active agents for coating aids, emulsifiers, infiltration-improving agents for processing solution, defoamers, or agents for controlling various physical properties of the light-sensitive material, described in, e.g. U.S. Patents 3,026,202 and 3,514,293, British Patents 548,532 and 1,216,389, U.S. Patent 3,726,683, including anionic, cationic, nonionic and amphoteric compounds; mordants described in, e.g. U.S. Patents 2,113,381 and 2,548,564; antistaining agents described in, e.g. U.S. Patents 2,360,210, 2,728,659, 2,732,300 and 3,700,453, particularly 2 - methyl - 5 - hexadecylhydroquinone, 2 methyl - 5 - sec - octadecylhydroquinone and 2,5 - di - t - octylhydroquinone, etc.; antistatic agents described in, e.g. U.S. Patents 2,882,157, 2,972,535 and 3,573,093 and British Patent 1,378,584 and U.S. Patents 3,549,369,3,704,128 and 3,663,230; matting agents described in, e.g. U.S. Patents 2,992,101 and 2,956,884, British Patent 1,221,980 and British Patent 1,307,373, particularly silica gel having a grain size of 0.5-20 C and polymethylmethacrylate having a grain size of 0.5-20 p; developing promotors, e.g. benzyl alcohol and polyoxyethylene series compounds which may be added in the processing 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- or microsensitive 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 as if the infectious development takes place at the position of the exposed silver halide in the gelatin layer due to predominant supply of the semiquinone.

It is accordingly essential in the process of the invention to treat with a developing solution containing a hydroquinone developing agent. The lith type developing solution (infectious developing solution), however, is not essentially required as far as the solution is of hydroquinones by which high contrast lith type silver image may sufficiently be obtained even in the presence of sulfite ion in a high concentration. The process of the invention differs apparently from the conventional processes in that no conventional lith type developing solution which contains hydroquinone, alkali, alkali metal bromide, sulfite ion in low concentration, and as a preserver a condensation product of formaldehyde/sodium bisulfite of carbonylbisulfite amine is needed, although the use of such components may of course be possible.

As the hydroquinone type developing agents employed according to the invention are mentioned, e.g. hydroquinone, chlorohydroquinone, bromohydroquinone, isopropylhydroquinone, toluhydroquinone, methylhydroquinone, 2,3 - dichlorohydroquinone, 2,5 - dimethylhydroquinone, 2,3 - dibromohydroquinone, 2,5 - dihydroxyacetophenone, 2,5 - diethylhydroquinone, 2,5 - di - p phenethylhydroquinone, and 2,5 - dibenzoylaminohydroquinone.

The developing solution containing the hydroquinones developing agent employed in the invention includes not only the so-called lith type developing agent but also the gradient MQ and PQ developing solution, the latters of which are advantageously employed in the invention because of the easiness of preparation and superior preservability. Among these developing solutions, those show the superadditivity are preferred. For example, the developing agents and the additives therefor described in "The Theory of Photographic Process", Third Edition, pp 374-378 (1966) are advantageously employed. A preserver like sulfite salts such as sodium sulfite, potassium sulfite or ammonium sulfite may jointly be employed in the developing solution used in the invention without impairing the effect of the invention; and this is another characteristic of the invention. The adjustment of pH and giving a buffer function with an alkali hydroxide, alkali carbonate or amine, or addition or inorganic development retarder such as potassium bromide or of organic development retarder such as benzotriazole may optionally be carried out as in the standard black and white developing solution.

In the invention the phrase "treat with a developing solution containing hydroquinones developing agent" means to carry out development of the exposed material of the invention with the developing solution which satisfies the abovementioned conditions, and various modes may be included therein. For example, the temperature at which development is carried out is preferably below 50"C, more preferably around 30"C, and the time required for development is generally within 30 minutes, more preferably within 5 minutes, by which good results are obtained, in general.

After the development, the subsequent processes such as washing, stopping stabilizing and fixing are carried out. If necessary, processes like prehardening and neutralization and the like may be adopted, but they may optionally be omitted. The processes may be carried out either by the so-called manual treatment like bath- or tray-development or by the mechanical treatment like 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 that the conventinal 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 often used for the conventional high contrast developing solution to the developing solution employed in the invention gives no undesirable influence on the photographic quality.

As can be clearly understood by the explanations given above, the invention relates to a novel light-sensitive silver halide photographic material and the processing method thereof which may obtain a superior stable line- or dot-image by processing the light-sensitive silver halide photographic material comprising a sensitizing dye, a tetrazolium salt and a silver halide having a narrow grain size distribution, with a developing solution containing hydroquinone, using no infectious developing solution.

According to the process of the invention, there is obtained a stable high contrast silver image even when the diffusible tetrazolium compound is employed.

There may also be obtained a stable dot image which is superior to that obtained by the method described in Japanese Patent Provisional Publication No. 52-18317 (1972), when the non-diffusible tetrazolium compound is employed.

The invention is further concretely explained by the following Examples, which by no means restrict the scope of the invention and various many modified embodiments may be possible: Example 1 A silver chlorobromide-gelation emulsion in fine grain size state containing silver halide of 90 mole % of silver chloride, 9 mole % of silver bromide and 1 mole % of silver iodide was chemically sensitized with a sulfur and gold sensitizing agent.

This emulsion had an average grain size of 0.25 p and 75% of the whole grains were within a range of 0.19 to 0.31 pin grain size. To this emulsion 8 g of 2,3,5-triphenyltetrazolium chloride per one mole of silver and the equimolar amount of diethylhexylsuccinate sulfonate (hereintoafter, referred to as DES) were added.

This emulsion was coated on a polyethylene telephthalate support so as to contain 53 mg of silver/100 cm2 and 50 mg of gelatin/100 cm2. Next this photographic element was wedge-exposed through a gray contact screen of intermediate tone with a tungsten lamp and processed by the following treatments at 300 C.

Development 1.5 minutes Water washing Fixing 2 Water washing 5 Drying.

The following composition were employed in the processing bath: [Developing solution] Metol 3.5 g Anhydrous sodium sulfite 60 g Hydroquinone 9.0 g Sodium carbonate 54 g Potassium bromide 2.5 g 5-Nitrobenzimidazole 0.5 g l-Phenyl-5-mercaptotetrazole 10 mg Water to make 1 litre (pH = 10.25) [Fixing solution] Ammonium thiosulfate decahydrate 150 mg Anhydrous sodium sulfite 10 g Sodium acetate trihydrate 15 g Glacial acetic acid 15 ml Water to make I litre (pH = 6.80) "Dot quality" here in the examples of this invention means an estimated value of reproduced halftone dot images. Halftone images obtained from the exposed and then developed lith type light-sensitive photographic material are composed of the part called generally "shadow dot" and the part known as "highlight part". There is an intermediate part of various areas in size between both the ends. "Dot quality" here means an evaluated value of the dot in the part having 50% dot in which a half of a definite area is clear and the rest of it is a developed image and the dot quality is expressed in progressive scale. That is, "4" means excellence and "1" extremely badness. The dot quality below 3 can not be generally permitted.

To this emulsion was incorporated exemplified sensitizing dye No. 14 dissolved in methanol in an amount of 200 mg per one mole of silver (Sample 2).

The results obtained are shown in Table 1.

TABLE 1

r Sensitizing Development Relative Dot Sample dye time (s) sensitivity Fog quality No addition of 60 60 0.01 3.0 the dye (outside 1 of this invention) 80 100 0.02 3.7 100 120 0.03 3.3 120 130 0.04 3.0 60 70 0.01 7.3 Compound No. 14 2 (within this 80 95 0.02 3.7 invention) 100 100 0.02 3.7 120 110 0.02 3.3 Table 1 shows that the light-sensitive material according to this invention does not vary in specific sensitivity and fog with the development time compared with other materials than this invention and the variation of dot quality is also small.

Example 2 A silver halide emulsion was prepared which comprises a silver chlorobromide emulsion containing silver halide of 60 mole % of silver chloride and 40 mole % of silver bromide and of which the average grain size is 0.3 p and 75 /0 of the whole grains is within a range of 0.24 to 0.37 p.

To this emulsion hexaamminecobalt (Ill) trichloride was added in amount of 4.0 g per one mole of silver. After the sensitizing dye No. 10 was added in an amount of 200 mg per one mile of silver, the emulsion was coated on a polyethylene terephthalate support so as to contain 55 mg of silver per 100 cm2 and 30 mg of gelatin per 100 cm2 and dried.

(Sample 3) Next, a similar sample was prepared as above except that 3.0 g of 2.5 diphenyl-3-a - naphthtyltetrazolium chloride (35) was added instead of hexaamminecobalt (III) trichloride.

(Sample 4) These samples were treated in the same way as in Example 1 together with Sample 5 containing no oxidant.

The results are shown in Table 2.

TABLE 2

Development Relative Dot Sample time(s) sensitivity Fog quality Sample 3 60 30 - 2.0 (outside of this invention) 80 50 0.01 2.3 100 80 0.01 2.5 120 150 0.02 2.0 Sample 4 60 80 0.01 2.7 80 100 0.01 3.5 (within this invention) 100 110 0.01 3.3 120 130 0.01 3.0 . . ~ extremely Sample 5 60 130 0.03 bad (outside of 80 180 0.07 this invention) 100 220 0.10 120 280 0.20 Table 2 shows that Sample 4 of this invention has an excellent dot quality compared with Samples 3 and 5.

Having regard to the provisions of Section 9 of the Patents Act 1949, attention is directed to the claims of our co-pending British Patent Applications No. 31013/76 (Serial No. 1560544) nad 31450/77 (Serial No. 1589593).

WHAT WE CLAIM IS: 1. A light-sensitive silver halide photographic material to be treated with a hydroquinones containing developing solution which comprises a support, at least one hydrophilic colloidal layer coated thereon which contains silver halide grains

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Example 2 A silver halide emulsion was prepared which comprises a silver chlorobromide emulsion containing silver halide of 60 mole % of silver chloride and 40 mole % of silver bromide and of which the average grain size is 0.3 p and 75 /0 of the whole grains is within a range of 0.24 to 0.37 p. To this emulsion hexaamminecobalt (Ill) trichloride was added in amount of 4.0 g per one mole of silver. After the sensitizing dye No. 10 was added in an amount of 200 mg per one mile of silver, the emulsion was coated on a polyethylene terephthalate support so as to contain 55 mg of silver per 100 cm2 and 30 mg of gelatin per 100 cm2 and dried. (Sample 3) Next, a similar sample was prepared as above except that 3.0 g of 2.5 diphenyl-3-a - naphthtyltetrazolium chloride (35) was added instead of hexaamminecobalt (III) trichloride. (Sample 4) These samples were treated in the same way as in Example 1 together with Sample 5 containing no oxidant. The results are shown in Table 2. TABLE 2 Development Relative Dot Sample time(s) sensitivity Fog quality Sample 3 60 30 - 2.0 (outside of this invention) 80 50 0.01 2.3 100 80 0.01 2.5 120 150 0.02 2.0 Sample 4 60 80 0.01 2.7 80 100 0.01 3.5 (within this invention) 100 110 0.01 3.3 120 130 0.01 3.0 . . ~ extremely Sample 5 60 130 0.03 bad (outside of 80 180 0.07 this invention) 100 220 0.10 120 280 0.20 Table 2 shows that Sample 4 of this invention has an excellent dot quality compared with Samples 3 and 5. Having regard to the provisions of Section 9 of the Patents Act 1949, attention is directed to the claims of our co-pending British Patent Applications No. 31013/76 (Serial No. 1560544) nad 31450/77 (Serial No. 1589593). WHAT WE CLAIM IS:

1. A light-sensitive silver halide photographic material to be treated with a hydroquinones containing developing solution which comprises a support, at least one hydrophilic colloidal layer coated thereon which contains silver halide grains

having a number average grain size of 0.1 to 0.5 p, at least 80% of which grains being within a range of 0.7d to 1.3 times the average grain size, and the silver halide being silver chlorobromide or chloroiodobromide containing at least 50 mole% of silver chloride, a sensitizing dye, and a tetrazolium compound having the formula (1), (ill) or (111):

whereinR1,R3,R4, R5, R8, R9, R10and R each represents aryl, substituted aryl, or a heterocyclic group; R2, R6 and R7 each represents aryl, substituted aryl, a heterocyclic group, alkyl, substituted alkyl, hydroxy, carboxyl, or a salt thereof, amino, mercapto, cyano, acyl, nitro or hydrogen; D represents a divalent aromatic group; E represents alkylene, arylene, or aralkylene; said heterocyclic group being fur-2-yl, thien-2-yl, quinol-2-yl, benzoxazol-2-yl, thiadiazolyl, benzothiadiazolyl, oxazolyl, pyrimidinyl, pyridyl or 2,5-dimethyl-thiadiazolyl, X is an anion; and n is I or 2, provided that the compound forms an intramolecular salt when n is 1.

2. A light-sensitive silver halide photographic material according to Claim 1 wherein the tetrazolium compound is non-diffusible.

3. A light-sensitive silver halide photographic material according to Claim 1 wherein the tetrazolium compound is diffusible.

4. A light-sensitive silver halide photographic material according to any preceding Claim wherein the hydrophilic colloidal layer is a gelatin layer.

5. A light-sensitive silver halide photographic material according to any preceding Claim wherein the light-sensitive silver halide photographic material further comprises a protective layer having a thickness of 0.1-10 p on the hydrophilic colloidal layer.

6. A light-sensitive silver halide photographic material according to any preceding Claim, wherein the sensitizing dye has one of the formulae (IV) to (X).

wherein R21, R22 and R23 each represents an alkyl or substituted alkyl group, or an aryl or substituted aryl group; Ll, L2 and L2 each represents a methine or substituted methine group; Z1, Z2 and Z3 each represents an atom or atomic group necessary for forming a 5 to 6 membered heterocyclic ring; P and Q each represents cyano, -COOR4. -COR4 or MO2R4 in which R4 represents an alkyl group; Q, and Q2 each represent an atomic group necessary for forming a substituted or unsubstituted thiooxazolone ring, a pyrazolone ring, an oxyindole ring, a barbituric acid, a 2-thiobarbituric acid, a 2,4-oxazolidine-dione ring, a 2,4thiazolidinedione ring, a 2,4-imidazolidinedione ring, a 2-thio-2,4-oxazolidinedione ring, a 2-thio-2,4-thiazolidinedione ring, a 2-thio-2,4-selenazolidinedione ring, a 2-thio-2,5-thiazolidinedione ring, a 2-thio-hydantoin ring, a 4-oxazolinone ring, a 4-thiazolinone ring or a 4-imidazoline ring; Y represents hydrogen, amino, alkylamino, dialkylamino, halogen, an alkoxy group or an alkyl group; m, and m2 each represents 0 or 1; n1 and n2 each represent 0, 1 or 2; X represents an acid anion group; and 1 represents 1 or 2 provided that the compound forms an intramolecular salt when 1 is 1.

7. A light-sensitive silver halide photographic material according to Claim 6 wherein the senzitizing dye is one of the exemplified sensitizing compounds 1, 2, 3, 4,5,6,7,8,9, 10, II, 12, 13, 14, 15, 16, 17, 18, 19,20,21,22,23,24,25,26,27,28, and 29.

8. A light-sensitive silver halide photographic material according to Claim 6 wherein the hydrophilic colloidal layer contains the tetrazolium compound.

9. A light-sensitive silver halide photographic material according to Claim 8 wherein the hydrophilic colloidal layer further contains the sensitizing dye.

10. A light-sensitive silver halide photographic material according to Claim 6 wherein the photographic material further comprises a gelatin layer adjacent to the hydrophilic colloidal layer, the gelatin layer containing the tetrazolium compound while the hydrophilic colloidal layer contains the sensitizing dye.

11. A method of processing a light-sensitive silver halide photographic material according to any preceding Claim, after image-wise exposure to light, which comprises contacting the resulting exposed photographic material with a hydroquinone-containing developing solution.

12. A method according to Claim 11, wherein the developing solution contains Metol.

13. A method according to Claim 11 wherein the developing solution contains 1 -phenyl-3-pyrazolidone.

14.A method according to any of Claims 11 to 13 wherein the developing solution contains a sulfite salt in an amount of more than 10 g per litre.

15. A method according to Claim 14 wherein the pH-value of the developing solution is 8.5 to 12.

16. A light-sensitive silver halide photographic material as claimed in Claim 1 substantially as hereinbefore described with reference to either of the Examples.

17. A method according to Claim 11 and substantially as hereinbefore described with reference to either of the Examples.