Development of silver halide photosensitive material and developer

Abstract: Development of silver halide photosensitive material with a developer containing a developing agent and a free sulfite is accompanied by deposition of silver sludge. Silver sludge is effectively suppressed by adding to the developer (a) a six-membered heterocyclic compound which has a six-membered ring containing two nitrogen atoms and has a mercapto group, a hydroxyl group and one or two substituents having 2 to 20 carbon atoms in total or (a') a six-membered heterocyclic compound which has a six-membered ring containing three nitrogen atoms and has a mercapto group and a hydroxyl group.

Description: This invention relates to methods for developing a photographic silver halide photosensitive material and developers used therein to minimize silver stain or sludge on machine parts including a tank, a rack and rollers, thereby ensuring easier daily maintenance of the machine. In general, automatic developing machines or processors are often utilized for the development of silver halide photosensitive material from the standpoints of quickness and ease of operation and handling. The processors involve a series of steps of development, fixation, washing and drying. There is an increasing demand for more rapid development. One typical means for accelerating development is to increase the activity of developer. For the rapid development of Black-and-white photosensitive material, the activity of the developer may be increased by increasing the concentration of a developing agent or increasing the pH of the developer. It is, however, difficult to maintain the developer active because the developer undergoes substantial degradation by air oxidation. Another approach for rapid processing is related to the photosensitive material. Reducing the thickness of the photosensitive material (e.g., protective layer) is effective for rapid processing. It is well known from early days to use sulfites in order to prevent degradation of the developer. When the sulfites which are capable of dissolving silver halides are added to the developer, silver can be dissolved from the photosensitive material into the developer as a silver sulfite complex. As the silver complex is reduced in the developer, silver gradually deposits and accumulates on the developing tank and rollers. This is known as silver sludge or stain. Since silver sludge can deposit on the photosensitive material being processed thus staining images, the processor should be washed at intervals, that is, periodic maintenance is necessary. If the amount of sulfite added is increased, the amount of the silver sulfite complex dissolving is also increased and the degree of silver sludging is accordingly increased, offsetting the benefits of rapid processing. One known method for reducing silver sludge is the addition of a compound capable of diminishing silver ions dissolving into the developer and/or controlling reduction of silver ions into silver as disclosed in Japanese Patent Application Unexamined Publication (JP-A) No. 24347/1981. This method, however, inevitably retards the development itself and lowers the sensitivity. A low sensitivity is a serious drawback for a photosensitive material/development system which is desired to have as high sensitivity as possible. Although it is quite effective for rapid processing to reduce the thickness of the photosensitive material (e.g., protective layer), processing of such a relatively thin photosensitive material through the processor on the running mode suffers from the problem that more silver ions are dissolved into the developer, aggravating silver sludging. The method of JP-A 24347/1981 is insufficient in preventing silver sludging. There is a desire for further improvement. Japanese Patent Publication (JP-B) Nos. 46585/1981 and 2895/1987 disclose another method for reducing silver sludging by adding selected compounds. The compounds described therein have an improved anti-sludging function, but they are not necessarily stable and immediately lose their activity in the system when the developer is subject to air oxidation. There is a need for a further improvement. Mercaptopyrimidine compounds are known from early days and some have been utilized in the photographic art. US Patent No. 3,240,603 and UK Patent No. 957,807 utilize mercaptopyrimidine compounds as fixing agents for silver halides. High pH solutions of mercaptopyrimidine compounds in high concentrations are effective fixers. In fact, at least 8 g of mercaptopyrimidine compound is used in US Patent No. 3,240,603. JP-B 24464/1985 utilizes mercaptopyrimidine compounds in a bleach-fixing solution for promoting the bleaching action. German Patent No. 21 26 297 utilizes mercaptopyrimidine compounds in the second developer of a color reversal system for the purpose of increasing the sensitivity thereof. Exemplary is 2-mercapto-4-hydroxy-6-methylpyrimidine. Evaluating this compound, the inventors found that it is effective for preventing silver sludge from depositing, but to a less extent. There is a need for a further improvement. US Patent No. 3,597,199 utilizes mercaptopyrimidine derivatives in the second developer of a color reversal system for the purpose of improving photographic properties. Exemplary is 2-mercapto-4-hydroxy-6-aminopyrimidine. Evaluating this compound, the inventors found that it does not have a satisfactory function of preventing silver sludge. JP-A 204037/1984 utilizes heterocyclic mercapto compounds in black-and-white developer at pH 11.5 or higher for the purpose of preventing silver sludging. One exemplified compound is 2-mercapto-4-hydroxypyrimidine. Testing this compound, we found that it is not necessarily effective for preventing silver sludging. JP-B 35493/1973 utilizes heterocyclic mercapto compounds in developers for preventing silver sludging. Exemplary is 2-mercapto-4-hydroxy-6-methylpyrimidine. It is effective for preventing silver sludge from depositing to a less extent as mentioned above. UK Patent No. 1,296,161 uses mercaptopyrimidine derivatives in developers of the silver salt diffusion transfer type for the purpose of preventing silver sludging. Exemplary is 2-mercapto-4-hydroxy-6-carboxyquinazoline. Evaluating this compound, the inventors found that it does not have a satisfactory function of preventing silver sludge. As mentioned above, there are known a number of examples utilizing mercaptopyrimidine compounds in a processing solution. Several mercaptopyrimidine compounds are used as fixers in concentrated high pH solution form while some are known as agents for preventing silver sludge. Since heretofore known mercaptopyrimidine compounds are not fully effective for preventing silver sludge, there is a need for a substantial improvement. JP-B 121854/1989 discloses a black-and-white developer which contains an amino or heterocyclic compound having a group capable of adsorbing silver halide for achieving improved photographic quality and preventing black pepper. Exemplary are 1-morpholinopropyl-5-mercaptotetrazole and 1-morpholinoethyl-2-mercaptoimidazole. These compounds were not found to be fully effective for preventing silver sludge. Several mercaptotriazine compounds have been used in the photographic art. JP-B 24464/1985 uses a mercaptotriazine in a bleach-fixer for promoting bleaching. JP-A 5334/1974 adds a heterocyclic mercapto compound to a lith developer to thereby remove trailing of a photographic high contrast photosensitive material. Exemplary is 2,4,6-trimercapto-1,3,6-triazine. JP-A 204037/1984 discloses a black-and-white developer at pH 11.5 or higher which contains a heterocyclic mercapto compound, for example, 2,4-dimercapto-6-hydroxy-1,3,5-triazine for preventing silver sludge. JP-A 53244/1991 uses mercapto-1,3,5-triazine in a developer for preventing silver sludge. An example is 2,4-dimercapto-6-hydroxy-1,3,5-triazine again. Evaluating these compounds, we found that they do not have a satisfactory function of preventing silver sludge. One prior art image toner is 1-phenyl-5-mercaptotetrazole (see T.H. James, The Theory of the Photographic Process, Ch. 16, page 476) which greatly affects the photographic properties such as fog, sensitivity and gradation. There is a desire for a method capable of approximating yellow brown color tone to completely neutral with minimal influence on the photographic properties. It is the object of the present invention to provide a developer composition, a method for developing a silver halide photosensitive material and a method for processing a silver halide photosensitive material resulting in rapid processing of the silver halide photosensitive material, whereby silver sludging in a developing tank and/or on a developing rack and rollers, is reduced the maintenance of an automatic processor or developing instrument is facilitated, silver sludging is reduced without any influence of the photographic properties and without impairing the stability of the developer, and the image tone is improved without any influence on the photographic properties. As described in the preamble, mercaptopyrimidine compounds were used at high pH as fixing agents for silver halide. It is expected that the addition of such a compound to a developer at high pH is disadvantageous for anti-silver-sludging purpose because the amount of silver dissolving into the developer would increase. In fact, testing 2-mercapto-4-hydroxypyrimidine exemplified in JP-A 204037/1984, we found that it is not so effective as an anti-sludging agent. Quite unexpectedly, we have found that specific compounds are very effective in preventing silver sludging and improving image tone, overcoming the outstanding problems. In a first aspect, the present invention provides a developer composition for a silver halide photosensitive material comprising a compound of the general formula wherein R₁ and R₂ are independently selected from the group consisting of a hydrogen a halogen atom, an alkyl, aryl aralkyl, hydroxyl, mercapto, carboxyl, sulfo, phosphono, nitro, cyano, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl and alkoxy group, the sum of carbon atoms of R₁ and R₂ ranging from 2 to 20, and R₁ and R₂ taken together may form a saturated ring structure. Furthermore, the present invention is directed to a method for developing a silver halide photosensitive material after exposure comprising the step of treating the material with the above developer composition, as well as a method for processing a silver halide photosensitive material after exposure comprising the steps of developing and fixing the material for forming an image therein, wherein in the developing step the material is treated with a developer, containing a) the above developer composition, b) a dihydroxybenzene developing agent, c) at least 0.3 mol/l of a free sulfite and d) at least one developing agent selected from 1-phenyl-3-pyrazolidone and aminophenol. As mentioned in the preamble, JP-A 204037/1984 and 53244/1991 use a mercaptotriazine, 2,4-dimercapto-6-hydroxy-1,3,5-triazine in a developer. A test of this compound revealed that it does not function as a satisfactory antisludging agent. Investigating a number of mercaptotriazine compounds, we have found that a mercaptotriazine compound having one mercapto group and one hydroxy group is effective in preventing silver sludge and improving image tone. In a second aspect of the present invention, there is provided a developer composition for a silver halide photosensitive material comprising a six-membered heterocyclic compound of the general formula (II) or (III): wherein R₃ and R₄ are independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl, aryl, aralkyl, carboxyl, sulfo, phosphono, sulfoamino, nitro, cyano, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl, alkoxy, aryloxy, alkylthio, arylthio and heterocyclic group with the proviso that the compound of the general formula (II) is not Furthermore the present invention is directed to a method for developing a silver halide photosensitive material after exposure comprising the step of treating the material with the above developer composition, as well as a method for processing a silver halide photosensitive material after exposure comprising the steps of developing and fixing the material for forming an image therein, wherein in the developing step the material is treated with a developer containing (a) the above developer composition, components (b) and (c) as mentioned above and (d) at least one developing agent selected from 3-pyrazolidone and aminophenol. If R₁ and R₂ in the compound of the general formula (I) are an alkyl, aryl, aralkyl, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl or alkoxy group, they may have a substituent which is as exemplified for R₁ and R₂. Preferably, R₁ and R₂ are such that either one of R₁ and R₂ is a substituted or insubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 12 carbon atoms, and a halogen atom or R₁ and R₂ taken together form a saturated 5-or 6-membered ring. More preferably, R₁ is a hydrogen atom or an alkyl group having an amino group or heterocyclic ring as a substituent and R₂ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms or R₁ and R₂ taken together form a saturated 5-or 6-membered ring. For example, R₁ is a dimethylaminomethyl, morpholinomethyl, N-methylpiperazinylmethyl or pyrrolidinylmethyl group and R₂ is a methyl, ethyl, phenyl or p-methoxyphenyl group. Several illustrative examples of the six-membered heterocyclic compound of formula (I) are given below. The compounds of formula (I) may be readily synthesized by the methods described in Comprehensive Heterocyclic Chemistry, Volume 3, pages 40-56, 106-142, 179-191, and the Journal of American Chemical Society, Volume 67, 2197-2200 (1945). The compound of formula (I) is preferably added in an amount of about 0.01 to 5 g, more preferably about 0.05 to 3 g per l of the developer. It is known from JP-B 40339/1989 that good graininess and low fog are achievable by adding to a developer an anti-fogging compound of formula (IV) or (V): wherein R₅ is a hydrogen or halogen atom, or alkyl, nitro or cyano group. Examples of the compound of formula (IV) include indazole, 4-nitroindazole, 5-nitroindazole, 6-nitroindazole, 5-cyanoindazole, and 5-chloroindazole. Examples of the compound of formula (V) include benzotriazole, 5-methylbenzotriazole, 5-chlorobenzotriazole, and 5-bromobenzotriazole. Preferred are 5-nitroindazole and 5-methylbenzotriazole. These antifoggants are preferably added in amounts of 0.01 to 10 g, more preferably 0.02 to 5 g per l of the developer. A black-and-white developer containing a high concentration of sulfite causes silver to be dissolved from the photosensitive material into the developer as a silver sulfite complex. For preventing silver sludging, it is effective to reduce the amount of silver that can be dissolved from the photosensitive material into the developer. If the compound of formula (I) is used in large quantities, say, more than 5 g, it will function as a fixing agent. Thus the amount of the compound of formula (I) added should be limited. We have found that the use of a compound of formula (I) in combination with a compound of formula (IV) or (V) is quite effective in reducing the amount of silver dissolved from a photosensitive material into a developer. If R₃ and R₄ in the compounds of the general formula (II) or (III) are an alkyl, aryl aralkyl, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl, alkoxy, aryloxy, alkylthio, arylthio, or heterocyclic group, they may have a substituent which is as exemplified for R₃ and R₄. Preferred examples of the substituents R₃ and R₄ include hydrogen, substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, substituted or unsubstituted aryl groups having 6 to 12 carbon atoms, substituted or unsubstituted aralkyl groups having 7 to 12 carbon atoms, carboxyl, sulfo, sulfoamino, nitro and cyano groups, and halogen atoms. More preferably, R₃ and R₄ each are a hydrogen atom, an unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, or a substituted or unsubstituted aralkyl group having 7 to 10 carbon atoms. Several illustrative examples of the six-membered heterocyclic compound which has a six-membered ring containing three nitrogen atoms and a mercapto group and a hydroxyl group are given below. The compound of the general formula (II) and (III) may be readily synthesized by the methods described in Chemische Berichte, Volume 104, 1606-1610 (1971), the Journal of American Chemical Society, Volume 78, 1938-1941 (1956), and Angewandte Chemie, Volume 66, 359-363 (1954). The compound of formula (II) or (III) is preferably added in an amount of about 0.01 to 10 g more preferably about 0.05 to 5g per 1 of the developer. Now, various components of the developer are described. The dihydroxybenzene developing agents (b) used in the developer include hydroquinone, chlorohydroquinone, bromohydroquinone, isopropylhydroquinone, methylhydroquinone, 2,3-dichlorohydroquinone, 2,5-dichlorohydroquinone, 2,3-dibromohydroquinone, 2,5-dimethylhydroquinone, and hydroquinone monosulfonate with hydroquinone being preferred. Examples of the p-aminophenol developing agent (d) used in the developer include N-methyl-p-aminophenol, p-aminophenol, N-(β-hydroxyethyl)-p-aminophenol, N-(4-hydroxyphenyl)glycine, 2-methyl-p-aminophenol, and p-benzylaminophenol, with N-methyl-p-aminophenol being preferred. Examples of the β-pyrazolidone developing agent (d) used herein include 1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-4-methyl-4-hydroxymethyl-3-pyrazolidone, 1-phenyl-4,4-dihydroxymethyl-3-pyrazolidone, 1-phenyl-5-methyl-3-pyrazolidone, 1-p-aminophenyl-4,4-dimethyl-3-pyrazolidone, 1-p-tolyl-4,4-dimethyl-3-pyrazolidone, and 1-p-tolyl-4-methyl-4-hydroxymethyl-3-pyrazolidone. The dihydroxybenzene developing agent is generally used in an amount of about 0.01 to 1.5 mol/l, preferably about 0.05 to 1.2 mol/l. In addition to the dihydroxybenzene developing agent, the p-aminophenyl or 3-pyrazolidone developing agent is generally used in an amount of about 0.0005 to 0.2 mol/l preferably about 0.001 to 0.1 mol/l. The sulfite preservatives (c) in the developer used according to the present invention include sodium sulfite, potassium sulfite, lithium sulfite, ammonium sulfite, sodium bisulfite, and potassium metabisulfite. The sulfite is used in an amount of at least about 0.3 mol/l. The preferred upper limit is 2.5 mol/l of developer concentrate. The developer is preferably at pH 9 to 13, more preferably pH 10 to 12. Alkaline agents are used for pH adjustment. Included are pH adjusting agents such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium tertiary phosphate, and potassium tertiary phosphate. Buffer agents are also useful, for example, borates as disclosed in JP-A 186259/1987, saccharose, acetoxime and 5-sulfosalicylic acid as disclosed in JP-A 93433/1985, phosphates, and carbonates. Preferably the developer further contains a chelating agent having a chelate stability constant of at least 8 relative to a ferric ion (Fe³⁺). The term "stability constant" is well known in the literature, for example, L. G. Sillen and A. E. Martell, "Stability Constants of Metal Complexes", The Chemical Society, London (1964) and S. Chaberek and A. E. Martell, "Organic Sequestering Agents", Willey (1959). Chelating agents having a stability constant of at least 8 relative to a ferric ion include organic carboxylic acid chelating agents, organic phosphoric acid chelating agents, inorganic phosphoric acid chelating agents, and polyhydroxy compounds. Illustrative examples include ethylenediaminedi-ortho-hydroxyphenylacetic acid, triethylenetetraaminehexaacetic acid, diaminopropanetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylglycine, ethylenediaminediacetic acid, ethylenediaminedipropionic acid, iminodiacetic acid, diethylenetriaminepentaacetic acid (DTPA), hydroxyethyliminodiacetic acid, 1,3-diamino-2-propanoltetraacetic acid, trans-cyclohexanediaminetetraacetic acid, ethylenediaminetetraacetic acid (EDTA), glycoletherdiaminetetraacetic acid, ethylenediamine-N,N,-N′,N′-tetrakismethylenephosphonic acid, nitrilo-N,N,N-trimethylenephosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, 1,1-diphosphonoethane-2-carboxylic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxy-1-phosphonopropane-1,2,3-tricarboxylic acid, catechol-3,5-disulfonic acid, sodium pyrophosphate, sodium tetrapolyphosphate, and sodium hexametaphosphate. Also used in the developer is a dialdehyde hardening agent or a bisulfite salt adduct thereof, for example, glutaraldehyde or a bisulfate salt adduct thereof. Additives other than the above-mentioned components include development retarders such as sodium bromide, potassium bromide, and potassium iodide; organic solvents such as ethylene glycol, diethylene glycol, triethylene glycol, dimethylformamide, methyl cellosolve, hexylene glycol, ethanol, and methanol; and antifoggants, for example, mercapto compounds such as 1-phenyl-5-mercaptotetrazole and sodium 2-mercaptobenzimidazole-5-sulfonate, and indazole compounds such as 5-nitroindazole, and benzotriazole compounds such as 5-methylbenzotriazole. Also added are development promoters as disclosed in Research Disclosure, Vol. 176, No. 17643, Item XXI (December 1978), and if desired, color toning agents, surfactants, debubbling agents, and water softeners. Anti-silver-sludging agents other than those used in the present invention may be added to the developer in the practice of the present invention, for example, the compounds described in JP-A 24347/1981. To the developer may be added amino compounds, for example, alkanol amines as described in EP-A 0136582, UK Patent No. 958678, US Patent No. 3,232,761, and JP-A 106244/1981 for the purposes of promoting development and increasing contrast. Other useful additives are described in L.F.A. Mason, "Photographic Processing Chemistry," Focal Press (1966), pages 226-229; US Patent Nos. 2,193,015 and 2,592,364, and JP-A 64933/1973. In the practice of the invention, the above-mentioned development is followed by fixation using a fixer which is an aqueous solution containing a thiosulfate at pH 3.8 or higher, preferably pH 4.2 to 7.0. The fixing agents include sodium thiosulfate and ammonium thiosulfate although the ammonium thiosulfate is preferred with respect to the fixing rate. The fixing agent is added in a varying amount, generally from about 0.1 to 6 mol/l. The fixer may contain water soluble aluminum salts serving as a hardening agent, for example, aluminum chloride, aluminum sulfate, and potassium alum. The fixer may contain tartaric acid, citric acid, gluconic acid or derivatives thereof alone or in admixture of two or more. These compounds are effectively added in an amount of at least 0.005 mol per l of the fixer, especially 0.01 to 0.03 mol/l. If desired, the fixer may further contain preservatives (e.g., sulfites and bisulfites), pH buffer agents (e.g., acetic acid and boric acid), pH adjusting agents (e.g., sulfuric acid), chelating agents capable of softening hard water, and the compounds disclosed in JP-A 78551/1987. Several terms are defined in conjunction with a sequence of successively processing a length or sheet of photosensitive material through a developing tank, a fixing tank, a washing tank, and then a drying section of an automatic processor. "Developing process time" or "developing time" is a duration taken from the point when the leading edge of a photosensitive material is dipped in the developing tank liquid in a processor to the point when it is subsequently dipped in the fixer. "Fixing time" is a duration taken from the point when the leading edge is dipped in the fixing tank liquid to the point when it is dipped in the washing tank liquid (or stabilizer). "Washing time" is a duration when the photosensitive material is dipped in the washing tank liquid. "Drying time" is a duration when the photosensitive material passes through the processor drying section where hot air at 35 to 100°C, preferably 40 to 80°C is usually blown. In the practice of the invention, the developing time generally ranges from 5 seconds to 1 minute, preferably from 5 to 30 seconds while the developing temperature ranges from 25 to 50°C, preferably from 25 to 40°C. The fixing time generally ranges from 5 seconds to 1 minute at a temperature of about 20 to 50°C, preferably from 5 to 30 seconds at a temperature of about 25 to 40°C. For water washing or stabilizing bath, the time generally ranges from 5 seconds to 1 minute at a temperature of 0 to 50°C, preferably from 5 to 30 seconds at a temperature of 15 to 40°C. After development, fixation and washing (or stabilization), the photosensitive material is removed of the wash water, that is, squeezed of water through squeeze rollers and then dried. Drying is generally at about 40 to 100°C. The drying time may vary with the ambient condition, usually in the range of from about 5 seconds to 1 minute, preferably from about 5 to 30 seconds at 40 to 80°C. The photographic photosensitive materials which can be processed with the developer composition of the present invention include conventional black-and-white photosensitive materials and color photosensitive materials subject to a reversal process (e.g., color reversal film and paper). Particularly useful are laser printer photographic materials for recording medical images, graphic printing photosensitive materials, medical direct radiographic photosensitive materials, medical photofluorographic photosensitive materials, hydrazine nucleating high contrast films, photosensitive materials for recording CRT display images, microphotographic photosensitive materials, general black-and-white negative films and print papers, and the like. The photosensitive materials to which the present invention is applicable bear thereon a photographic silver halide emulsion. The emulsion is a dispersion of silver halides such as silver chloride, silver iodide, silver bromide, silver chlorobromide, silver iodobromide, and silver chloroiodobromide in a hydrophilic colloid. In general, silver halide emulsions are prepared by mixing water-soluble silver salts (e.g., silver nitrate) and water-soluble halides in the presence of water and a hydrophilic colloid in accordance with conventional well-known techniques, for example, single jet, double jet, and controlled jet techniques, followed by physical ripening and chemical ripening such as gold and/or sulfur sensitization. No particular limit is imposed on the shape of silver halide grains used herein. Cubic, octahedral and spherical silver halide grains may be used as well as plate-shaped grains having a high aspect ratio as described in Research Disclosure, 22534 (January 1983). In the case of X-ray sensitive material, emulsions of plate-shaped silver halide grains are advantageous. Preferred are silver bromide or silver iodobromide grains, with silver iodobromide grains containing up to 10 mol%, especially 0 to 5 mol% of silver iodide being most preferred for rapid processing because of high sensitivity. The plate-shaped grains have an aspect ratio which is defined as the ratio of the average diameter of a circle having an equal area to the projected area of individual grains to the average thickness of the individual grains. Preferably the plate-shaped grains have an aspect ratio of from 4 to less than 20, more preferably from 5 to 10 while the thickness is preferably up to 0.3 µm, especially up to 0.2 µm Preferably the plate-shaped grains are present in an amount of at least 80% by weight, more preferably at least 90% by wight of the total weight of silver halide grains. The use of plate-shaped silver halide grains does not only help to achieve a more stable photographic performance during the running process according to the present invention, but also reduces the silver coverage, imposing less loads on the fixing and drying steps which is advantageous for rapid processing. With respect to plate-shaped silver halide grains, reference is made to Cugnac and Chateau, "Evolution of the Morphology of Silver Bromide Crystals during Physical Ripening", Science et Industrie Photography, Vol. 33, No. 2 (1962), pp. 121-125, Duffin "Photographic Emulsion Chemistry", Focal Press, New York, 1966, pp. 66-72, and A.P.H. Tribvlli & W.F. Smith, Photographic Journal, Vol. 80, p. 285 (1940). For their preparation, reference is made to JP-A 127921/1983, 113927/1983 and 113928/1983. It is also possible to prepare plate-shaped silver halide grains by forming seed crystals containing more than 40% by weight of plate-shaped grains in an atmosphere having a relatively low pBr value, typically pBr ≦ 1.3 and concurrently adding silver salt and halide solutions while maintaining the pBr value substantially unchanged, allowing the seed to grow. Desirably, silver salt and halide solutions are carefully added so that no crystal nuclei are newly generated during the grain growth process. The dimensions of plate-shaped silver halide grains may be adjusted by adjusting the temperature, selecting the type and amount of solvent, and controlling the addition rate of silver salt and halide during grain growth. The silver halide emulsion used herein may be either a multi-dispersed one or a mono-dispersed one having a narrow grain size distribution. Mono-dispersed emulsions having a dispersion coefficient of up to 20% are preferred for graphic printing photosensitive materials. By the term mono-dispersed emulsion is meant a silver halide emulsion having a grain size distribution with a coefficient of variation of up to 20%, especially up to 15%. The coefficient of variation is defined as (standard deviation of grain size)/(average of grain size) x 100%. The silver halide grains may have a uniform phase or different phases between the interior and the surface. Also useful is a mixture of two or more types of silver halide emulsions which are separately formed. The silver halide grains may be ones in which a latent image is mainly formed at the surface or ones in which a latent image is mainly formed internally. Grains having a previously fogged surface are also acceptable. In the silver halide emulsion used herein, a cadmium salt, sulfite salt, lead salt, thallium salt, rhodium salt or complex salt, and iridium salt or complex salt may be copresent during formation or physical ripening of the silver halide grains. Particularly when it is desired to impart a high contrast or to improve a reciprocity law failure, it is preferred to prepare a silver halide emulsion while an iridium salt is present in an amount of 10⁻⁸ to 10⁻³ mol per mol of the silver halide. The silver halide emulsion used herein may also contain at least one of iron, rhenium, ruthenium, and osmium compounds in an amount of up to 10⁻³ mol, preferably 10⁻⁶ to 10⁻⁴ mol per mol of silver. If necessary, the silver halide emulsion used herein may be chemically sensitized. Chemical sensitization may be effected by well-known methods such as sulfur, reduction and gold sensitization methods. Preferred is sulfur sensitization. The sulfur sensitizing agents include sulfur compounds contained in gelatin and various sulfur compounds, for example, thiosulfates, thioureas, thiazoles, and rhodanines. Exemplary compounds are described in US Patent Nos. 1,574,944, 2,278,947, 2,410,689, 2,728,668, 3,501,313, and 3,656,955. Preferred sulfur compounds are thiosulfates and thioureas. Chemical sensitization favors pAg 8.3 or lower, especially pAg 7.3 to 8.0. Satisfactory results are also obtained with the use of polyvinyl pyrrolidone in combination with a thiosulfate as reported by Moisar, Klein & Gelatione, Proc. Symp., 2nd, 301-309 (1970). Gold sensitization is typical of noble metal sensitization methods and uses gold compounds, often gold complex salts. Also useful are complex salts of noble metals other than gold, such as platinum, palladium and iridium. Exemplary salts are described in US Patent No. 2,448,060 and UK Patent No. 618,061. The reduction sensitizing agents include stannous salts, amines, sulfinoformamidine, dialkylaminoborans, and silanes, examples of which are described in US Patent Nos. 2,487,850, 2,518,698, 2,694,637, 2,983,609 and 2,983,610. Preferably, the silver halide grains used herein are spectrally sensitized with sensitizing dyes. The dyes used herein include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes, and hemioxonol dyes. Particularly useful dyes among them are cyanine, merocyanine, and complex merocyanine dyes. For these dyes, any nucleus generally utilized for cyanine dyes can be applied as a basic heterocyclic ring nucleus. Most preferred are carbocyanine sensitizing dyes. Specific examples are described in Research Disclosure, Vol. 170, RD-17643 (December 1978), page 23, US Patent Nos. 4,425,425 and 4,425,426. In general, the sensitizing dye is added to the emulsion prior to its application to a suitable support although it may be added during the chemical ripening step or the silver halide grain forming step. The emulsion layer of the photosensitive material used herein may contain plasticizers, for example, polymers such as alkyl acrylate latexes, emulsions thereof, and polyols such as trimethylol propane. The photosensitive material used herein may further contain surfactants in its photographic emulsion layer or another hydrophilic colloid layer for the purposes of coating aid, antistatic, slippage improvement, emulsion dispersion, anti-sticking and photographic property improvement (e.g., development promotion, high contrast, and sensitization). Examples of the surfactant include nonionic surfactants, for example, saponins (steroids), alkylene oxide derivatives (e.g., polyethylene glycol, polyethylene glycol/polypropylene glycol condensates, polyethylene glycol alkyl ethers, polyethylene glycol alkyl aryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkyl amines and amides, and polyethylene oxide adducts of silicones), glycidol derivatives (e.g., alkenyl succinic acid polyglycerides and alkylphenol polyglycerides), polyhydric alcohol fatty acid esters, and saccharide alkyl esters; anionic surfactants having an acidic group such as a carboxy, sulfo, phospho, sulfate or phosphate group, for example, alkyl carbonates, alkyl sulfonates, alkylbenzenesulfonates, alkylnaphthalene sulfonates, alkyl sulfates, alkyl phosphates, N-acyl-N-alkyltaurines, sulfosuccinate esters, sulfoalkylpolyoxyethylene alkylphenyl ethers, and polyoxyethylene alkylphosphate esters; ampholytic surfactants, for example, amic acids, aminoalkylsulfonates, aminoalkylsulfates and phosphates, alkylbetaines, and aminooxides; and cationic surfactants, for example, alkyl amine salts, aliphatic or aromatic quaternary ammonium salts, heterocyclic quaternary ammonium salts (e.g., pyridinium and imidazolium), and aliphatic or heterocyclic phosphonium and sulfonium salts. In general, the photographic silver halide photosensitive material used herein has at least one silver halide emulsion layer on a support. In the case of medical direct radiographic photosensitive material, at least one silver halide emulsion layer is present on each side of a support as described in JP-A 111934/1983, 127921/1983, 90841/1984, and 201235/1986. If desired, the photosensitive material used herein may have an intermediate layer, filter layer, and anti-halation layer. In the photosensitive material used herein, the silver halide emulsion is preferably applied in an amount of 0.5 to 5 g of silver/m² of each surface, more preferably about 1 to 3 g of silver/m² of each surface. The upper limit of 5 g/m² of silver should not be exceeded with respect to a rapid processing ability. At least 0.5 g/m² of silver is necessary to provide a satisfactory image density and contrast. The binder or protective colloid of the photographic emulsion is advantageously gelatin although other hydrophilic colloids may be used. Useful are synthetic hydrophilic high-molecular weight substances, for example, gelatin derivatives, graft polymers of gelatin and other polymers, protein hydroxyethyl celluloses such as albumin and casein, cellulose derivatives such as carboxymethyl cellulose and cellulose sulfate ester, sodium alginate, saccharide derivatives such as starch derivatives, and homopolymers and copolymers such as polyvinyl alcohol, polyvinyl alcohol partial acetal, poly-N-vinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylimidazole, and polyvinylpyrazole. The gelatin used may be lime treated gelatin, acid treated gelatin, hydrolyzed gelatin, or enzymatically decomposed gelatin. It is preferred that the emulsion layer or another hydrophilic colloid layer contains an organic substance which will leach out during development step, especially in the case of X-ray sensitive material. Where the leachable substance is gelatin, a species of gelatin which does not participate in the crosslinking reaction of gelatin with a hardening agent is preferred. Examples include acetylated gelatin and phthalated gelatin, with those of lower molecular weight being preferred. High molecular weight substances other than gelatin include polyacrylamides as disclosed in US Patent No. 3,271,158, and hydrophilic polymers such as polyvinyl alcohol and polyvinyl pyrrolidone while saccharides such as dextran, saccharose, and pluran are also useful. Among these, polyacrylamides and dextran are preferred, with polyacrylamides being most preferred. These substances preferably have an average molecular weight of up to 20,000, more preferably up to 10,000. The amount of organic substance leached out during processing is from 10 to 50% of the total weight of the organic substance coated other than silver halide grains. Preferably 15 to 30% of the organic substance extinguishes during processing. The layer containing the organic substance which can be leached out during processing may be an emulsion layer or a surface protective layer. If the total amount of the organic substance coated is fixed, it is preferred to distribute the organic substance in both the emulsion layer and the surface protective layer and more preferably solely in the surface protective layer rather than solely in the emulsion layer. Where the photosensitive material has a plurality of emulsion layers, it is preferred to add a higher proportion of the organic substance in an emulsion layer nearer to the surface protective layer if the total amount of the organic substance coated is fixed. There may be contained matte agents, for example, organic compounds such as a homopolymer of polymethyl methacrylate, a copolymer of methyl methacrylate and methacrylic acid, and starch and inorganic compounds such as silica, titanium dioxide, strontium and barium sulfate, all in fine particulate form. The preferred particle size ranges from about 1.0 to 10 µm, especially from about 2 to 5 µm. The photographic silver halide photosensitive material used herein may have a photographic emulsion layer or another layer colored with a dye for the purposes of absorbing a selected spectrum of light, that is, achieving halation or irradiation or providing a filter layer for controlling the spectrum of light to enter the photographic emulsion layer. In the case of double side films such as medical direct radiographic films, a layer for cutting crossover may be provided below the emulsion layer. Examples of the dye used for these purposes include oxonol dyes having a pyrazolone or barbituric acid nucleus, azo dyes, azomethine dyes, anthraquinone dyes, arylidene dyes, styryl dyes, triarylmethane dyes, merocyanine dyes, and cyanine dyes. On use of such dyes, it is effective to mordant an anionic dye to a selected layer in the photosensitive material by using a polymer having a cationic site. In this case, a dye which undergoes irreversible discoloration in the development-fixation-washing sequence is preferably used. The layer to which the dye is mordanted using a polymer having a cationic site may be an emulsion layer, a surface protective layer, or a layer remote from the emulsion layer with respect to the support, but preferably a layer between the emulsion layer and the support. It is ideal to mordant an undercoat layer of medical X-ray double side film for crossover cutting purposes. As coating aids in the undercoat layer there may be used a nonionic surfactant of the polyethylene oxide type in combination with a polymer having a cationic site. Preferably, the polymer having a cationic site is selected from anion exchange polymers. Various well-known quaternary ammonium salt and phosphonium salt polymers are useful anion exchange polymers. The quaternary ammonium salt and phosphonium salt polymers are described in the following publications as mordant polymers and antistatic polymers. Examples include water-dispersible latexes disclosed in JP-A 30328/1978, 92274/1979, 126027/1979, 155835/1979, 142339/1980, and 166940/1984 and USP 3,958,995; polyvinyl pyridinium salts disclosed in USP 2,548,564, 3,148,061 and 3,756,814; water-soluble quaternary ammonium salt polymers disclosed in USP 3,709,690; and water-insoluble quaternary ammonium salt polymers disclosed in USP 3,898,088. On use, it is preferred to convert such a polymer latex into a water-soluble crosslinked polymer latex by copolymerizing it with a monomer having at least 2, preferably 2 to 4, ethylenically unsaturated groups in order to prevent the polymer latex from migrating from the selected layer to another layer or into the processing solution to exert a photographically undesirable influence. For fixing the dye, a solid dispersion method as disclosed in JP-A 155350/1980 and WO 88/04794 is also effective. The photosensitive material used herein may be designed to exhibit ultrahigh contrast photographic properties using hydrazine nucleating agents. This system and hydrazine nucleating agents used are described in the following literature and patents. Research Disclosure, Item 23516 (November 1983), page 346 and the literature cited therein; US Patent Nos. 4,080,207, 4,269,929, 4,276,364, 4,278,748, 4,385,108, 4,459,347, 4,560,638, 4,478,928, 4,686,167; UK Patent No. 2,011,391B; EP 217,310; and JP-A 179734/1985, 170733/1986, 270744/1986, 000948/1987, 178246/1987, 270948/1987, 029751/1988, 032538/1988, 104047/1988, 121838/1988, 129337/1988, 223744/1988, 234244/1988, 234245/1988, 234246/1988, 294552/1988, 306438/1988, 010233/1989, 090439/1989, 276128/1989, 280747/1989, 283548/1989, 283549/1989, 285940/1989, 002541/1990, 139538/1990, 177057/1990, 198440/1990, 198441/1990, 198442/1990, 196234/1990, 196235/1990, 220042/1990, 221953/1990, 221954/1990. The system is especially useful in graphic art. The hydrazine nucleating agent is incorporated in a photographic photosensitive material, preferably into a silver halide emulsion layer or less preferably into another non-photosensitive hydrophilic colloid layer (e.g., protective layer, intermediate layer, filter layer, and anti-halation layers). The amount of hydrazine nucleating agent added preferably ranges from 1x10⁻⁶ to 5x10⁻² mol, more preferably from 1x10⁻⁵ to 2x10⁻² mol per mol of silver halide. Development accelerators or agents for promoting nucleating transfer phenomenon useful for this ultrahigh contrast system are the compounds described in JP-A 077616/1978, 137133/1978, 037732/1979, 014959/1985, and 140340/1985, and various compounds containing an N or S atom. These accelerators are preferably added in an amount of 1.0x10⁻³ to 0.5 g/m², more preferably 5.0x10⁻³ to 0.1 g/m² although the optimum amount varies with the type of accelerator. Additionally, the photosensitive material used herein may contain various additives for the purposes of preventing fog during preparation, shelf storage and photographic processing of the photosensitive material and stabilizing photographic performance. Useful additives include a number of compounds generally known as antifoggants and stabilizers, for example, azoles (e.g., benzothiazolium salts), nitroindazoles, chlorobenzimidazoles, bromobenzimidazoles, mercaptotetrazoles, mercaptothiazoles, mercaptobenzothiazoles, mercaptothiadiazoles, aminotriazoles, benzothiazoles, nitrobenzotriazoles, etc.; mercaptopyrimidines; pyrimidines; mercaptotriazines; thioketo compounds (e.g., oxazolinethion); azaindenes, for example, triazaindenes, tetraazaindenes (e.g., 4-hydroxy-substituted-(1,3,3a,7)-tetraazaindenes), and pentaazaindenes; benzenethiosulfonic acid, benzenesulfinic acid, and benzenesulfonic acid amide. Inter alia, benzotriazoles (e.g., 5-methylbenzotriazole) and nitroindazoles (e.g., 5-nitroindazole) are preferred. Alternatively, these compounds may be contained in processing solutions. Moreover, compounds which release retardants during development as described in JP-A 30243/1987 may be added as stabilizers or for black pepper inhibiting purpose. Further, the photographic photosensitive material used herein may contain a developing agent such as hydroquinone derivatives and phenidone derivatives as a stabilizer or accelerator. Also contained in the photographic photosensitive material used herein are organic or inorganic hardeners in a photographic emulsion layer or another hydrophilic colloid layer. Useful are chromium salts (e.g., chromium alum and chromium acetate), aldehydes (e.g., formaldehyde and glutaraldehyde), N-methylol compounds (e.g., dimethylol urea), dioxane derivatives, active vinyl compounds (e.g., 1,3,5-triacryloyl-hexahydro-s-triazine and 1,3-vinylsulfonyl-2-propanol), active halides (e.g., 2,4-dichloro-6-hydroxy-s-triazine), and mucohalogenic acids (e.g., mucochloric acid) alone or in admixture. The photographic photosensitive material used herein may also contain a hydroquinone derivative capable of releasing a development inhibitor in accordance with the density of an image during development (known as DIR-hydroquinones) in a photographic emulsion layer or another hydrophilic colloid layer. Useful examples are disclosed in US Patent Nos. 3,379,529, 3,620,746, 4,377,634, and 4,332,878, and JP-A 129536/1974, 067419/1979, 153336/1981, 153342/1981, 090435/1984, 090436/1984, 138808/1984, and 278853/1984. For the purposes of dimensional stability, the photosensitive material used herein may contain dispersions of water-insoluble or difficultly soluble synthetic polymers. Useful polymers have monomer components such as alkyl (meth)acrylate, alkoxy acryl (meth)acrylate, glycidyl (meth)acrylate alone or in admixture thereof or in combination with acrylic acid and methacrylic acid. Preferably, a compound having an acid group is contained in a silver halide emulsion layer or another layer of the photographic photosensitive material used herein. Examples of the compound having an acid group include organic acids such as salicylic acid, acetic acid, and ascorbic acid, and polymers and copolymers having a recurring unit of an acid monomer such as acrylic acid, maleic acid, and phthalic acid. For these compounds, reference is made to JP-A 223834/1986, 228437/1986, 025745/1987, and 055542/1987. Especially preferred among these compounds are ascorbic acid as a typical low-molecular weight compound and a water-dispersible latex of a copolymer between an acid monomer (e.g., acrylic acid) and a cross-linkable monomer having two or more unsaturated groups (e.g., divinyl benzene) as a typical high-molecular weight compound. The silver halide emulsion thus prepared is applied to a suitable support as a cellulose acetate film and a polyethylene terephthalate (PET) film by conventional coating techniques such as dipping, air knife, bead, extrusion doctor, and double coating techniques, followed by drying. The present invention is also applicable to color photosensitive materials. In this case, a variety of color couplers are used. The color coupler used herein is a compound capable of coupling reaction with an oxidized form of an aromatic primary amine developing agent for forming a dye. Typical examples of the useful color coupler include naphthol and phenol compounds, pyrazolone and pyrazoloazole compounds, and open ring or heterocyclic ketomethylene compounds. Illustrative examples of the cyan, magenta and yellow couplers which can be used herein are described in Research Disclosure, RD 17643 (December 1978), item VII-D and RD 18716 (November 1979) and the patents cited therein. A variety of photographic additives which can be used herein are described in RD 17643, pages 23-28 and RD 18716, pages 648-651. They are listed below together with the pages to be referred to in the literature. Letters R and L mean right and left columns of the page. EXAMPLE Examples of the present invention are given below by way of illustration. In the examples, Mw is a molecular weight. The anti-sludging compounds used in the invention are identified with the numbers in the chemical formula lists previously described. Examples 1 to 6 demonstrate the effectiveness of compounds of formula (I). Example 1 (1) Preparation of plate-shaped grains To 1 l of water in a container were added 4.5 g of potassium bromide, 20.6 g of gelatin, and 2.5 ml of an aqueous solution of 5% thioether HO(CH₂)₂S(CH₂)₂S(CH₂)₂OH. While the solution was kept at 60°C, with stirring, 37 ml of an aqueous silver nitrate solution (3.43 g of silver nitrate) and 33 ml of an aqueous solution containing 2.97 grams of potassium bromide and 0.363 g of potassium iodide were added to the container over 37 seconds by a double jet mixing method. Then, an aqueous solution containing 0.9 g of potassium bromide was added and thereafter, the container was heated to 70°C and 53 ml of an aqueous silver nitrate solution (4.90 g of silver nitrate) was added over 13 minutes. To the container was added 15 ml of 25% aqueous ammonia. After 20 minutes of physical ripening at the temperature, 14 ml of a 100% acetic acid solution was added to the solution for neutralization. Subsequently, an aqueous solution containing 133.3 g of silver nitrate and an aqueous potassium bromide solution were added to the solution over 35 minutes by a controlled double jet method while maintaining the solution potential at pAg 8.5. Then, 10 ml of a 2N potassium thiocyanate solution and 0.10 mol% based on the total silver content of AgI fine particles having a particle diameter of 0.07 µm were added. After physical ripening for 5 minutes at the temperature, the solution was cooled to a temperature of 35°C. There were obtained plate-shaped grains having a total silver iodide content of 0.36 mol%. The grains had an average projection area diameter of 1.05 µm and a thickness of 0.175 µm. Thereafter, the soluble salts were removed by sedimentation. The temperature was raised to 40°C again and 30 g of gelatin and 2.35 g of phenoxyethanol, and 0.8 g of sodium polystyrenesulfonate as a thickener were added to the emulsion, which was adjusted to pH 5.90 and pAg 8.25 with sodium hydroxide and silver nitrate solutions. The emulsion was subjected to chemical sensitization while it was maintained at 56°C with stirring. First, 0.043 mg of thiourea dioxide was added and the emulsion was maintained for 22 minutes under these conditions for reduction sensitization. Thereafter, 20 mg of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene and 500 mg of the following compound were added to the emulsion. Additionally, 0.83 g of calcium chloride was added. Subsequently, 3.3 mg of sodium thiosulfate, 2.6 mg of chloroauric acid, and 90 mg of potassium thiocyanate were added to the emulsion which was maintained for 40 minutes under the same conditions. Then the emulsion was cooled to 35°C. The preparation of plate-shaped grains was completed in this way. (2) Preparation of emulsion coating composition A coating composition was prepared by adding the following chemicals to the emulsion in the amounts reported per mol of silver halide in plate-shaped grain form. (3) Preparation of surface protective laver coating composition The surface protective layer coating composition was prepared so as to form a surface protective layer consisting of the following components in the following coating weight. (4) Preparation of support (4-1) Preparation of dye for undercoat layer The following dye was ball milled in accordance with the teaching of JP-A 197943/1988. A ball mill was charged with 434 ml of water and 791 ml of an aqueous solution of 6.7% Triton X-200 surfactant (TX-200). To the mixed solution was added 20 g of the dye. The mill was charged with 400 ml of zirconium oxide (ZrO) beads having a diameter of 2 mm and the contents were milled for 4 days. Then 160 g of 12.5% gelatin was added to the mill. After debubbling, the ZrO beads were removed by filtration. The resulting dye dispersion was observed to find that the milled dye had a wide distribution of particle size ranging from 0.05 to 1.15 µm in diameter with a mean particle size of 0.37 µm. Coarse dye particles having a size of 0.9 µm or larger were centrifugally removed. There was obtained a dye dispersion. (4-2) Preparation of support A biaxially oriented PET film of 183 µm thickness was furnished. The PET film contained 0.04% by weight of a dye of the following structure. The film on one surface was treated with a corona discharge, coated with a first undercoat liquid of the following composition to a buildup of 5.1 ml/m² means of a wire bar coater, and then dried for one minute at 175°C. Then, a first undercoat layer was similarly formed on the opposite surface of the film. First undercoat composition Next, a second undercoat layer of the following composition was coated on each of the first undercoat layers on opposite surfaces of the film by means of a wire bar coater and then dried at 150°C. (5) Preparation of photographic material The emulsion coating composition and the surface protective layer coating composition both formulated as above were coated on each surface of the above-prepared support by a co-extrusion method. The amount of silver coated was 1.75 g/m² on each surface. The amounts of gelatin and hardener added to the emulsion layer were adjusted to provide a swelling factor of 230% as determined by a freeze dry method using liquefied nitrogen. A photographic material was obtained in this way. (6) Preparation of developer There were prepared developer concentrate parts A, B and C and starter having the following compositions. Developer (diluted to 10 l) Part A Part B Part C Starter A service solution was prepared by sequentially dissolving 2.5 l of part A, 250 ml of part B and 250 ml of part C in about 6 l of water with stirring, diluting the solution with water to 10 l, and adjusting the pH to 10.40. This service solution is a developer replenisher. A tank developer was prepared by adding 20 ml of the starter to 1 l of the developer replenisher. For fixation, a fixer Fuji F (manufactured by Fuji Photo-Film Co., Ltd.) was used. (7) Processing Using a roller conveyor type automatic processor model FPM-9000 (manufactured by Fuji Photo-Film Co., Ltd.), the photographic material prepared in (5) was processed in the sequence of Table 1. This sequence is a rapid process of 45 seconds. A series of runs used different developers which were prepared by adding anti-sludging agents to the developer replenisher formulated in (6) as shown in Table 2. It is to be noted that the comparative compound is a compound of JP-A-204037/1984 having the following formula: The processor was operated 6 days a week. On every operating day, 100 quarter size (25,4 x 30,5cm (10x12 inches)) sheets of half-exposed photographic material were processed. This running process was continued over two weeks, with the accumulative number of processed sheets amounting to 1,200. For evaluating the photographic properties of the photosensitive material by sensitometry, it was exposed stepwise through an optical wedge. The photographic properties examined are sensitivity (S), fog, average gradient (G), and maximum density (Dm). Sensitivity (S) is reported as a relative value on the basis that the reciprocal of an exposure required to provide a blackening degree of fog +1.0 is 100. Fog was determined as a net density increase with a correction for base density. Average gradient (G) is the gradient of a straight line connecting a density of fog +0.25 and a density of fog +2.0. The results of the running test are shown in Table 3 together with the silver sludging observations. Test Nos. 101 to 106 correspond to developer Nos. D101 to D106, respectively. As seen from Table 3, test Nos. 101 and 102 using developers D101 and D102 were satisfactory in photographic properties, but quite unsatisfactory in silver sludging. Silver sludging caused the processor to be contaminated internally, imposing a heavy burden on the maintenance of the processor. Silver sludging also caused staining of photosensitive material, leaving a serious problem with respect to the management of image quality. In contrast, test Nos. 103 to 106 using developers D103 to D106 containing the anti-sludging agents used according to the present invention were successful in minimizing silver sludging with little influence on the photographic properties. Example 2 (1) Preparation of AgI fine grains To 2 l of water were added 0.5 g of potassium iodide and 26 g of gelatin. To the solution at 35°C, 80 ml of an aqueous solution containing 40 g of silver nitrate and 80 ml of an aqueous solution containing 39 g of potassium iodide were added over 5 minutes stirring. The flow rates of silver nitrate and potassium iodide solutions were both 8 ml/min at the start of addition and linearly accelerated so that addition of each 80 ml was complete within 5 minutes. After grains were formed in this way, the soluble salts were removed by sedimentation at 35°C. The dispersion was then heated to 40°C, combined with 10.5 g of gelatin and 2.56 g of phenoxyethanol, and adjusted to pH 6.8 with sodium hydroxide. There was obtained 730 g of a mono-dispersed emulsion containing AgI fine grains having a mean particle diameter of 0.015 µm. (2) Preparation of plate-shaped grains To 1 l of water in a container were added 4.5 g of potassium bromide, 20.6 g of gelatin, and 2.5 ml of an aqueous solution of 5% thioether HO(CH₂)₂S(CH₂)₂S(CH₂)₂OH. While the solution was kept at 60°C, with stirring, 37 ml of an aqueous silver nitrate solution (3.43 g of silver nitrate) and 33 ml of an aqueous solution containing 2.97 g of potassium bromide and 0.363 g of potassium iodide were added to the container over 37 seconds by a double jet mixing method. Then, an aqueous solution containing 0.9 g of potassium bromide was added and thereafter, the container was heated to 70°C and 53 ml of an aqueous silver nitrate solution (4.90 g of silver nitrate) was added over 13 minutes. To the container was added 15 ml of 25% aqueous ammonia. After 20 minutes of physical ripening at the temperature, 14 ml of a 100% acetic acid solution was added to the solution for neutralization. Subsequently, an aqueous solution containing 133.3 g of silver nitrate and an aqueous potassium bromide solution were added to the solution over 35 minutes by a controlled double jet method while maintaining the solution potential at pAg 8.5. Then, 10 ml of a 2N potassium thiocyanate solution and 0.05 mol% based on the total silver content of AgI fine particles prepared in (1) were added. After physical ripening for 5 minutes at the temperature, the emulsion was cooled to a temperature of 35°C. There was obtained a monodispersion of plate-shaped grains having a total silver iodide content of 0.31 mol%, an average projection area diameter of 1.10 µm and a thickness of 0.165 µm, with a variation coefficient of diameter of 18.5%. Thereafter, the soluble salts were removed by sedimentation. The temperature was raised to 40°C again and 35 g of gelatin and 2.35 g of phenoxyethanol, and 0.8 g of sodium polystyrenesulfonate as a thickener were added to the emulsion, which was adjusted to pH 5.90 and pAg 8.25 with sodium hydroxide and silver nitrate solutions. The emulsion was subjected to chemical sensitization while it was maintained at 56°C with stirring. First, 0.043 mg of thiourea dioxide was added and the emulsion was maintained for 22 minutes under these conditions for reduction sensitization. Thereafter, 20 mg of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene and 500 mg of the following compound were added to the emulsion. Additionally, 1.1 g of calcium chloride aqueous solution was added. Subsequently, 3.3 mg of sodium thiosulfate, 2.6 mg of chloroauric acid, and 90 mg of potassium thiocyanate were added to the emulsion which was maintained for 40 minutes under the same conditions. Then the emulsion was cooled to 35°C. The preparation of plate-shaped grains was completed in this way. (3) Preparation of emulsion coating composition A coating composition was prepared by adding the following chemicals to the emulsion in the amounts reported per mol of silver halide. (4) Preparation of surface protective layer coating composition The surface protective layer coating composition was prepared so as to form a surface protective layer consisting of the following components in the following coating weight. (5) Preparation of support (5-1) Preparation of dye for undercoat layer The following dye was ball milled in accordance with the teaching of JP-A 197943/1988. A ball mill was charged with 434 ml of water and 791 ml of an aqueous solution of 6.7% Triton X-200 surfactant (TX-200). To the mixed solution was added 20 g of the dye. The mill was charged with 400 ml of zirconium oxide (ZrO) beads having a diameter of 2 mm and the contents were milled for 4 days. Then 160 g of 12.5% gelatin was added to the mill. After debubbling, the ZrO beads were removed by filtration. The resulting dye dispersion was observed to find that the milled dye had a wide distribution of particle size ranging from 0.05 to 1.15 µm in diameter with a mean particle size of 0.37 µm. Coarse dye particles having a size of 0.9 µm or larger were centrifugally removed. There was obtained a dye dispersion. (5.2) Preparation of support A biaxially oriented PET film of 183 µm thickness was furnished. The PET film contained 0.04% by weight of a dye of the following structure. The film on one surface was treated with a corona discharge, coated with a first undercoat liquid of the following composition to a buildup of 5.1 ml/m² by means of a wire bar coater, and then dried for one minute at 175°C. Then, a first undercoat layer was similarly formed on the opposite surface of the film. First undercoat composition Next, a second undercoat layer of the following composition was coated on each of the first undercoat layers on opposite surfaces of the film by means of a wire bar coater and then dried at 150°C. (6) Preparation of photographic material The emulsion coating composition and the surface protective layer coating composition both formulated above were coated on each surface of the above-prepared support by a co-extrusion method. The amount of silver coated was 1.7 g/m² on each surface. A photographic material was obtained in this way. The photographic material was allowed to stand for 7 days at 25°C and RH 60% before the swelling factor of the hydrophilic colloid layer was measured. The thickness (a) of the dry film was determined by observing a cut section under a scanning electron microscope (SEM). The thickness (b) of the swollen film was determined by dipping the photographic material in distilled water at 21°C for 3 minutes, freeze drying it with liquefied nitrogen, and observing it under SEM. The swelling factor was calculated to be 225% in accordance with (b - a)/a x 100%. (7) Preparation of developer There were prepared a developer concentrate and a fixer concentrate having the following composition. Developer concentrate (diluted by a factor of 2.5) A service solution was prepared by diluting 400 ml of the developer concentrate with 600 ml of water and adjusting to pH 10.35. Fixer concentrate (diluted by a factor of 4) A service solution was prepared by diluting 250 ml of the fixer concentrate with 750 ml of water and adjusting to pH 5.0. (8) Processing A running test was carried out as in Example 1. Using a roller conveyor type automatic processor having an overall path length of 1950 mm, the photographic material prepared in (6) was processed with the developer (service solution) and then the fixer (service solution) in the sequence of Table 4. This sequence is a rapid process of 30 seconds. Running tests were carried out in the 30-second processing sequence using developers containing Compounds (1), (2) , (5), (6), (12), (13) , (15) , (18) and (20) used in the invention. Outstanding improvements in silver sludging were achieved as in Example 1 without substantial influence on photographic properties. Example 3 (1) Preparation of silver halide emulsion In a container, 40 g of gelatin was dissolved in 1 l of water. The container was heated at 53°C and charged with 6 g of sodium chloride, 0.4 g of potassium bromide, and 60 mg of the following compound. Then 600 ml of an aqueous solution containing 100 g of silver nitrate and 600 ml of an aqueous solution containing 56 g of potassium bromide and 7 g of sodium chloride were added to the solution by a double jet mixing chloride forming core grains containing 20 mol% of silver chloride. Thereafter, 500 ml of an aqueous solution containing 100 g of silver nitrate and 500 ml of an aqueous solution containing 40 g of potassium bromide, 14 g of sodium chloride and 10⁻⁷ mol/mol of silver of potassium hexachloroiridate (III) were further added to the solution by a double jet mixing method, forming a shell containing 40 mol% of silver chloride around the cores. There was obtained a monodispersion of cubic silver chlorobromide grains of the core/shell type having a mean grain size of 0.35 µm. After salt removal, the dispersion was combined with 40 g of gelatin, adjusted to pH 6.0 and pAg 8.5, and then chemically sensitized at 60°C with 2 mg of triethylthiourea, 4 mg of chloroauric acid and 0.2 g of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene. (2) Preparation of emulsion coating composition An emulsion coating composition was prepared by heating 850 g of the emulsion at 40°C and adding the following additives thereto. Emulsion coating composition (3) Preparation of surface Drotective laver coating composition on emulsion layer A container was heated at 40°C and charged with the following components to formulate a coating composition for forming a surface protective layer on the emulsion layer. Surface protective laver coatin composition (4) Preparation of back laver coating composition A container was heated at 40°C and charged with the following components to formulate a coating composition for forming a back layer. Back layer coatin composition (5) Preparation of surface protective layer coating composition on back layer A container was heated at 40°C and charged with the following components to formulate a coating composition for forming a surface protective layer on the back layer. Surface protective layer coating composition (6) Preparation of photosensitive material A PET support on one surface was coated with the back layer coating composition and the back layer surface protective layer coating composition so as to provide an overall gelatin coverage of 3 g/m². The support on the opposite surface was coated with the emulsion layer coating composition and the emulsion layer surface protective layer coating composition so as to provide a silver coverage of 2.5 g/m² and a surface protective layer gelatin coverage of 1 g/m². (7) Processing Using the photosensitive material prepared in (6), a running test was carried out as in Example 1. A roller conveyor type automatic processor model FPM-200 (manufactured by Fuji Photo-Film Co., Ltd.) was modified so as to complete overall processing within 30 seconds on a dry-to-dry basis as shown in Table 5. In a photographic test, the photosensitive material was allowed to stand at 25°C and RH 60% for 7 days and subjected to scanning exposure of 10⁻⁷ second at room temperature using semiconductor laser of 780 nm. Twelve developers were prepared from the developer (service solution) used in Example 2 by adding the compounds used in the present invention and comparative compounds 1 to 5 identified below in the amounts shown in Table 6. The processor was operated 6 days a week. On every operating day, 200 quarter size (25,4x30,5 (10x12 inches)) sheets of exposed photographic material were processed. This running process was continued over two weeks, with the accumulative number of processed sheets amounting to 2,400. The fixer used was the same as in Example 2. Both the developer and fixer were replenished in an amount of 20 ml per 25,4 x 30,5cm (10x12 inches). For evaluating the photographic properties of the photosensitive material by sensitometry, it was exposed and examined for sensitivity (S), fog, average gradient (G), and maximum density (Dm) as in Example 1. The results of the running test are shown in Table 7 together with the silver sludging observations. Test Nos. 301 to 312 correspond to developer Nos. D301 to D312, respectively. In the running test Nos. 307 to 312 using developers having compounds employed in the invention added thereto, silver sludge deposition was markedly reduced without substantial influence on photographic properties. Surprisingly, it was found that among mercaptopyrimidine compounds, the degree of silver sludging largely varies with the type of substituent. Quite unexpectedly, when the photosensitive material was treated with developers having the compounds used in the invention added thereto, the resulting image silver had an improved degree of blackness. With the developer free of the compound used in the invention (run No. 301), the image silver was tinted yellow, presenting an unpleasant impression to a viewer. This is probably due to a small grain size. The present invention is successful in overcoming the image tone problem. Example 4 The photosensitive material prepared in Example 3 was processed on a 30 second schedule by means of the same processor as used in Example 3 for examining photographic properties and the tone of developed silver images. Several developers were prepared from the developer (service solution) used in Example 2 by adding thereto anti-sludging agents, Compounds (1), (3), (5) (6) and (19) used in the invention. The fixer used was the same as in Example 2. The results are shown in Table 8. As can be seen from Table 8, run Nos. 402 to 406 with the developers containing the anti-sludging agents used in the invention achieved a marked improvement in silver image without substantial influence on photographic properties. The tone of a silver image was favorably improved in that was free of yellowness and had pure black tone finish. Example 5 (1) Preparation of emulsion An emulsion was prepared as follows. Part 1 Part 2 Part 3 Part 4 Part 5 With stirring, Parts 2 and 3 were concurrently added over 10 minutes to Part 1 maintained at 38°C and pH 4.5, forming nucleus grains of 0.16 µm. Subsequently, Parts 4 and 5 were concurrently added over 10 minutes to the solution. Grain formation was completed by further adding 0.15 g of potassium iodide. Then, the emulsion was washed with water by flocculation in a conventional manner, combined with gelatin, adjusted to pH 5.1 and pAg 7.5, and subjected to ortho-sensitization by adding an ortho-sensitizing dye of the following formula. Thereafter, by adding 8 mg of sodium thiosulfate and 12 mg of chloroauric acid, the emulsion was chemically sensitized at 65°C for achieving optimum sensitivity. To the emulsion were added 200 mg of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene as a stabilizer and phenoxyethanol as a preservative. Finally obtained was an emulsion of cubic silver iodochlorobromide grains containing 70 mol% of silver chloride and having a mean grain size of 0.2 µm (coefficient of variation 9%). (2) Preparation of photosensitive material An emulsion coating composition was prepared by adding to the emulsion 2.5 g per mol of Ag of hydroquinone and 50 mg per mol of Ag of 1-phenyl-5-mercaptotetrazole as anti-foggants, a polyethyl acrylate latex as a plasticizer in an amount of 25% based on the gelatin binder, 2-bis(vinylsulfonylacetamide)ethane as a hardener, and colloidal silica in an amount of 40% based on the gelatin binder. The emulsion coating composition was applied to a polyester support so as to provide a coverage: 3.0 g/m² of silver and 1.0 g/m² of gelatin. On the emulsion layer, lower and upper protective layers of the following compositions were coated at the same time. Lower protective layer The base support was also coated with a back layer and a back protective layer of the following compositions. Back layer Back protective layer (3) Processing There was prepared a developer of the following composition. Developer Twelve test developers were prepared by adding anti-sludging agents to the developer as shown in Table 10. The comparative compounds are as identified in Example 3. The photosensitive material prepared in (2) was exposed to a xenon flash lamp for a flashing time of 10⁻⁶ sec. through an interference filter having a peak at 488 nm and a continuous wedge. Using an automatic processor model FG-710NH (manufactured by Fuji Photo-Film Co., Ltd.), the photosensitive material was subjected to a running test under the following conditions. The running test included the following conditions. On every operating day, 200 full-size (50.8 cm x 61 cm) sheets of film were processed. This running process was continued over two weeks, with the accumulative number of processed sheets amounting to 2,400. The developer was replenished in an amount of 50 ml per full-size sheet. For fixation a fixer LF-308 (manufactured by Fuji Photo-Film Co., Ltd.) was used. It was replenished in an amount of 100 ml per full-size sheet. The photosensitive material processed was examined for photographic properties by sensitometry. The photographic properties examined are fog, average gradient (G), sensitivity (S), and maximum density (Dm). Average gradient (G) is the difference between density 3.0 and density 1.0 divided by the difference between the logarithm of an exposure providing density 3.0 and the logarithm of an exposure providing density 0.1. Sensitivity (S) is reported as a relative value on the basis that the reciprocal of an exposure required to provide a density of 1.5 when the photosensitive material is treated with fresh developer D501 is 100. The results of the running test are shown in Table 10 together with the silver sludging observations. Test Nos. 501 to 512 correspond to developer Nos. D501 to D512, respectively. As can be seen from Table 10, run Nos. 501 to 506 using developers D501 to D506 were satisfactory in photographic properties, but quite unsatisfactory in silver sludging. Silver sludging caused the processor to be contaminated internally, imposing a heavy burden on the processor maintenance. Silver sludging also caused staining of photosensitive material, leaving a serious problem with respect to the management of image quality. In contrast, test Nos. 507 to 512 using developers D507 to D512 containing the anti-sludging agents used in the present invention were successful in minimizing silver sludging with little influence on photographic properties. Example 6 First photosensitive emulsion layer Preparation of photosensitive emulsion A With stirring, an aqueous solution of 0.37M silver nitrate and a silver halide aqueous solution containing 1x10⁻⁷ mol of (NH₄)₃RhCl₆, 5x10⁻⁷ mol of K₃IrCl₆, 0.11 mol of potassium bromide and 0.27 mol of sodium chloride per mol of silver were added to an aqueous gelatin solution containing sodium chloride and 1,3-dimethyl-2-imidazolidinethion at 45°C over 12 minutes by a double jet method. There were obtained silver chlorobromide grains having a mean grain size of 0.20 µm and a silver chloride content of 70 mol% which served as nuclei. Thereafter, similarly, an aqueous solution of 0.63M silver nitrate and a silver halide aqueous solution containing 0.19 mol of potassium bromide and 0.47 mol of sodium chloride were added to the emulsion over 20 minutes by a double jet method. Then, a solution containing 1x10⁻³ mol of KI was added to the emulsion for conversion. The emulsion was washed with water by flocculation in a conventional manner, combined with 40 g of gelatin, and adjusted to pH 6.5 and pAg 7.5. Then 5 mg of sodium thiosulfate, 8 mg of chloroauric acid and 7 mg of sodium benzenethiosulfonate per mol of silver were added to the emulsion which was heated to 60°C for 45 minutes for chemical sensitization. To the emulsion were added 150 mg of 1,3,3a,7-tetraazaindene as a stabilizer, proxcel and phenoxyethanol. There were obtained cubic silver chlorobromide grains having a silver chloride content of 70 mol% and a mean grain size of 0.28 µm (coefficient of variation 9%). Coating of first emulsion layer To photosensitive emulsion A were added 1x10⁻³ mol per mol of Ag of 5-[3-(4-sulfobutyl)-5-chloro-2-benzoxazolidylidene]-1-hydroxyethoxyethyl-3-(2-pyridyl)-2-thiohydantoin as a sensitizing dye, 2x10⁻⁴ mol of 1-phenyl-5-mercaptotetrazole, 5x10⁻⁴ mol of a short-wavelength cyanine dye of the following structure, 200 mg/m² of a polymer of the following structure, 50 mg/m² of hydroquinone, 200 mg/m² of a polyethyl acrylate dispersion, 200 mg/m² of 1,3-bisvinylsulfonyl-2-propanol as a hardener, and 2.8x10⁻⁵ mol/m² of a hydrazine compound of the following structure. The resulting emulsion was coated on a support to a coverage: 3.6 g/m² of silver and 2.0 g/m² of gelatin. Cyanine dye Polymer Hydrazine Coating of intermediate layer Second photosensitive emulsion layer Preparation of photosensitive emulsion B With stirring, an aqueous solution of 1.0M silver nitrate and a silver halide aqueous solution containing 3x10⁻⁷ mol of (NH₄)₃RhCl₆, 0.3 mol of potassium bromide and 0.74 mol of sodium chloride per mol of silver were added to an aqueous gelatin solution containing sodium chloride and 1,3-dimethyl-2-imidazolidinethion at 45°C over 30 minutes by a double jet method. There were obtained silver chlorobromide grains having a mean grain size of 0.28 µm and a silver chloride content of 70 mol%. The emulsion was then washed with water by flocculation in a conventional manner, combined with 40 g of gelatin, and adjusted to pH 6.5 and pAg 7.5. Then 5 mg of sodium thiosulfate and 8 mg of chloroauric acid per mol of silver were added to the emulsion which was heated to 60°C for 60 minutes for chemical sensitization. To the emulsion was added 150 mg of 1,3,3a,7-tetraazaindene as a stabilizer. There were obtained cubic silver chlorobromide grains having a silver chloride content of 70 mol% and a mean grain size of 0.28 µm (coefficient of variation 10%). Coating of second emulsion layer Photosensitive emulsion B was dissolved again, and 1.0x10⁻³ mol per mol of silver of 5-[3-(4-sulfobutyl)-5-chloro-2-benzoxazolidylidene]-1-hydroxyethoxyethyl-3-(2-pyridyl)-2-thiohydantoin as a sensitizing dye and a solution containing 1.0x10⁻³ mol of KI were added thereto at 40°C. Further added were 2x10⁻⁴ mol of 1-phenyl-5-mercaptotetrazole, 50 mg/m² of a polyethyl acrylate dispersion, 4.0 wt% based on the gelatin of 1,3-bisvinylsulfonyl-2-propanol as a hardener, and 1.0x10⁻⁴ mol/m² of a redox compound of the following structure. The resulting emulsion was coated over the first emulsion layer to a coverage: 0.4 g/m² of silver and 0.5 g/m² of gelatin. Redox compound Coating of protective layer A protective layer was coated on the second emulsion layer using a composition containing 0.5 g/m² of gelatin, 0.3 g/m² of polymethyl methacrylate particles (mean particle size 2.5 µm) and the following surfactants. A polyester film support of 100 µm thickness was simultaneously coated with the first photosensitive emulsion layer as the lowermost layer, the intermediate layer, the second photosensitive emulsion layer, and the protective layer. The support on the opposite surface was coated with a back layer and a back protective layer. Back layer Dye: a mixture of dyes [a], [b] and [c] Back protective layer Processing There was prepared a developer of the following composition. Developer Several test developers were prepared by adding anti-sludging agents to the developer as shown in Table 11. The photosensitive material prepared above was exposed to 3200°K tungsten light through an optical wedge for sensitometry. Using an automatic processor model FG-710F (manufactured by Fuji Photo-Film Co., Ltd.), the photosensitive material was subjected to a running test under the same conditions as in Example 5 except that development was done at 34°C for 20 seconds and the developer was replenished in an amount of 60 ml per fullsize sheet. For fixation a fixer GR-F1 (manufactured by Fuji Photo-Film Co., Ltd.) was used. It was replenished in an amount of 100 ml per full-size sheet. The results of photographic properties in the running test are shown in Table 12 together with the silver sludging observations. Test Nos. 601 to 606 correspond to developer Nos. D601 to D606, respectively. It is seen from Table 12 that like Example 5, the running tests using developers containing the anti-sludging agents used in the present invention were successful in minimizing silver sludging with little influence on photographic properties. Examples 7 to 12 demonstrate the effectiveness of compounds of formula (II) or (III). Example 7 Example 1 was repeated except that the anti-sludging agent was replaced by compounds of formula (II) or (III). A series of runs used different developers which were prepared by adding anti-sludging agents to the developer replenisher formulated in (6) of Example 1 as shown in Table 13. It is to be noted that the comparative compound is a compound having the following formula in JP-A 204037/1984 and 53244/1991. The results of the running test are shown in Table 14 together with the silver sludging observations. Test Nos. 701 to 705 correspond to developer Nos. D701 to D705, respectively. As can be seen from Table 14, test Nos. 701 and 702 using developers D701 and D702 were satisfactory in photographic properties, but quite unsatisfactory in silver sludging. Silver sludging caused the processor to be contaminated internally, imposing a heavy burden on the maintenance of the processor. Silver sludging also caused staining of photosensitive material, leaving a serious problem with respect to the management of image quality. In contrast, test Nos. 703 to 705 using developers D703 to D705 containing the anti-sludging agents used in the present successful in minimizing silver sludging with little influence on photographic properties. Example 8 Example 2 was repeated except that the anti-sludging agent was replaced by compounds of formula (II) or (III). Running tests were carried out in the 30-second processing sequence using developers containing Compounds (52), (53), (54), (59), (60), (61), (62), (63), (72), (76) and (77) employed in the invention. Outstanding improvements in silver sludging were achieved without substantial influence on photographic properties. Example 9 Example 3 was repeated except that processing step (7) was changed as follows. Using the photosensitive material prepared in (6) of Example 3, a running test was carried out as in Example 1. A roller conveyor type automatic processor model FPM-2000 (manufactured by Fuji Photo-Film Co., Ltd.) was modified so as to complete overall processing within 30 seconds on a dry-to-dry basis. Several developers were prepared from the developer (service solution) used in Example 2 by adding anti-sludging agents of formula (II) or (III) thereto as in Example 1. The fixer used was the same as in Example 2. Both the developer and fixer were replenished in an amount of 20 ml per 10x12 inches. In a photographic test, the photosensitive material was allowed to stand at 25°C and RH 60% for 7 days and subjected to scanning exposure of 10⁻⁷ second at room temperature using semiconductor laser of 780 nm. In the running tests on the 30 second process using developers having Compounds (52), (53), (58), (59), (62), (66) and (81) used in the invention added thereto, silver sludging was markedly improved without substantial influence on photographic properties. Quite unexpectedly, when the photosensitive material was treated with developers having the compounds used in the invention added thereto, the resulting image silver had an improved degree of blackness. With the developer free of the compound used in the invention, the image silver was tinted yellow, presenting an unpleasant impression to an image viewer. This is probably due to a small grain size. The present invention is successful in overcoming the image tone problem. Example 10 Example 4 was repeated except that the anti-sludging agent was replaced by compounds of formula (II) or (III). The photosensitive material prepared in Example 3 was processed on a 30 second schedule by means of the same processor as used in Example 3 for examining photographic properties and the tone of developed silver images. Several developers were prepared from the developer (service solution) used in Example 2 by adding thereto anti-sludging agents, Compounds (52), (62), (63) and (66) used in the invention. The fixer used was the same as in Example 2. The results are shown in Table 15. As can be seen from Table 15, run Nos. 1002 to 1005 with the developers containing the anti-sludging agents used in the invention, no substantial influence was exerted on photographic properties, and the tone of a silver image was favorably improved in that it was free of yellowness and had pure black tone finish. Example 11 Example 5 was repeated except that processing step (3) was changed as follows. Six test developers were prepared by adding anti-sludging agents to the developer of Example 5 as shown in Table 16. The comparative compound is as identified in Example 7. The photosensitive material prepared in (2) of Example 5 was exposed to a xenon flash lamp for a flashing time of 10⁻⁶ sec through an interference filter having a peak at 488 nm and a continuous wedge. Using an automatic processor model FG-710NH (manufactured by Fuji Photo-Film Co., Ltd.), the photosensitive material was subjected to a running test under the following conditions. The running test included the following conditions. On every operating day, 100 full-size (50.8 cm x 61 cm) sheets of film were processed. This running process was continued over two weeks, with the accumulative number of processed sheets amounting to 1,200. The developer was replenished in an amount of 50 ml per full-size sheet. For fixation a fixer LF-308 (manufactured by Fuji Photo-Film Co., Ltd.) was used. It was replenished in an amount of 100 ml per full-size sheet. The photosensitive material processed was examined for photographic properties by sensitometry in the same manner as in Example 5. The results of the running test are shown in Table 17 together with the silver sludging observations. Test Nos. 1101 to 1105 correspond to developer Nos. D1101 to D1105, respectively. As can be seen Table 17, run Nos. 11001 and 1102 using developers D1101 and D1102 were satisfactory in photographic properties, but quite unsatisfactory in silver sludging. Silver sludging caused the processor to be contaminated internally, imposing a heavy burden on the processor maintenance. Silver sludging also caused staining of photosensitive material, leaving a serious problem with respect to the management of image quality. In contrast, test Nos. 1103 to 1105 using developers D1103 to D1105 containing the anti-sludging agents used in the present invention were successful in minimizing silver sludging with little influence on photographic properties. Example 12 Example 6 was repeated except that the anti-sludging agent was replaced by compounds of formula (II) or (III). Several test developers were prepared by adding anti-sludging agents to the developer of Example 6 as shown in Table 18. The comparative compound is as identified in Example 7. The results of photographic properties in the running test are shown in Table 19 together with the silver sludging observations. Test Nos. 1201 to 1206 correspond to developer Nos. D1201 to D1206, respectively. It is seen from Table 19 that the running tests using developers containing the anti-sludging agents used in the present invention were successful in minimizing silver sludging with little influence on photographic properties. For the development of silver halide photosensitive material with a developer, silver sludging or staining can be significantly suppressed by adding a six-membered heterocyclic compound of formula (I), (II) or (III) to the developer. Reduced silver sludging leads to easier maintenance of the processor and eliminates staining of photosensitive material being processed with the developer, assisting in consistently forming images of quality even in the case of a rapid process.

Claims: A developer composition for a silver halide photosensitive material comprising a compound of the general formula (I): wherein R₁ and R₂ are independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl, aryl, aralkyl, hydroxyl, mercapto, carboxyl, sulfo, phosphono, nitro, cyano, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl and alkoxy group, the sum of carbon atoms of R₁ and R₂ ranging from 2 to 20, and R₁ and R₂ taken together may form a saturated ring structure. The developer composition of claim 1 wherein in formula (I) either one of R₁ and R₂ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 12 carbon atoms or a halogen atom or R₁ and R₂ taken together form a saturated 5-or 6-membered ring. The developer composition of claim 1 wherein in formula (I) R₁ is a hydrogen atom or an alkyl group having an amino group or a heterocyclic ring as a substituent and R₂ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms or R₁ and R₂ taken together form a saturated 5- or 6-membered ring. The developer composition of claim 1 wherein the compound of formula (I) is Compound (5) or (6): A method for developing a silver halide photosensitive material after exposure comprising the step of treating the material with a developer composition of any of claims 1 to 4. A method for processing a silver halide photosensitive material after exposure comprising the steps of developing and fixing the material for forming an image therein, wherein in the developing step the material is treated with a developer containing (a) a developer composition of any of claims 1 to 4, (b) a dihydroxybenzene developing agent, (c) at least 0.3 mol/l of a free sulfite and (d) at least one developing agent selected from 1-phenyl-3-pyrazolidone and aminophenol. A developer composition for a silver halide photosensitive material comprising a six-membered heterocyclic compound of the general formula (II) or (III): wherein R₃ and R₄ are independently selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl, aryl, aralkyl, carboxyl, sulfo, phosphono, sulfoamino, nitro, cyano, alkoxycarbonyl, aryloxycarbonyl, carbamoyl, sulfamoyl, alkoxy, aryloxy, alkylthio, arylthio and heterocyclic group, with the proviso that the compound of the general formula (II) is not A method for developing a silver halide photosensitive material after exposure comprising the step of treating the material with a developer composition of claim 7. A method for processing a silver halide photosensitive material after exposure comprising the steps of developing and fixing the material for forming an image therein, wherein in the developing step the material is treated with a developer containing (a) a developer composition of claim 7, (b) a dihydroxybenzene developing agent, (c) at least 0.3 mol/l of a free sulfite, and (d) at least one developing agent selected from 3-pyrazolidone and aminophenol.

Inventors: HAYAKAWA HIROSHI C O FUJI PHOT, HIRANO MITSUNORI C O FUJI PHOT, MORIMOTO KIYOSHI C O FUJI PHOT, TOYODA TAKASHI C O FUJI PHOTO, HAYAKAWA, HIROSHI, C/O FUJI PHOTO FILM CO., LTD., HIRANO, MITSUNORI, C/O FUJI PHOTO FILM CO., LTD., MORIMOTO, KIYOSHI, C/O FUJI PHOTO FILM CO., LTD., TOYODA, TAKASHI, C/O FUJI PHOTO FILM CO., LTD.
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD.
Application year: 1992
Main classification: G03C5
IPC codes: G03C5