EP0122125B1

EP0122125B1 - Silver halide emulsion

Info

Publication number: EP0122125B1
Application number: EP19840302347
Authority: EP
Inventors: Akihiko Miyamoto; Hideki Takiguchi; Syoji Matsuzaka; Hiroshi Kashiwagi; Yoshiyuki Nonaka
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 1983-04-06
Filing date: 1984-04-05
Publication date: 1987-07-15
Also published as: EP0122125A1; JPH027445B2; JPS59185329A; DE3464812D1

Description

This invention relates to a silver halide emulsion, more particularly to a silver halide emulsion having a high sensitivity and an improved fogging property.
With respect to light-sensitive silver halide photographic materials, particularly light-sensitive silver halide color photographic materials, there has recently been a strong desire for high sensitivity capable of coping with a wide range of conditions for photography in dark places, accurate photographing of even a rapidly moving object and so on. Thus, there have been developed the sulfur sensitization technique, the selenium sensitization technique and so on which are useful as chemical ripening methods for enhancement of the sensitivity of a silver halide emulsion which has hitherto been used for the above-mentioned light-sensitive material. Of the above-mentioned sensitization techniques, the selenium sensitization technique has received much attention being suitable for higher sensitization.
Selenium sensitization techniques as mentioned above, are described in the following specifications or Publications, for example, US-A-1,574,944; 1,602,592; 1,623,499; 2,642,361; 2,739,060; 3,297,446; 3,420,670; 3,320,069; 3,658,540; 3,408,196; 3,408,197; 3,442,653 and 3,591,385; GB-A-255,846 and 861,984; DE-B-1,033,510 and 2,547,762; FR-B-2,093,038 and 2,093,209; and JA-B-34491/1977; 34492/1977; 295/1978; 36009/1977; 38408/1977 and 22090/1982. The conventional selenium sensitization is useful for sensitization of a photographic material, particuarly for improving the sensitivity in the toe portion of the characteristic curve. However, this method has disadvantages in that it is accompanied by occurrence of fog, and by increase of fog during the storage of a photographic material.
A method for removing the above-mentioned problems in the selenium sensitization is described in, for example, JA-B-20970/1974, which discloses a selenium sensitization method applied to a monodispersed silver halide emulsion. However, this method can not achieve sufficiently high sensitivity and causes a problem of environmental pollution due to the toxicity of a mercury compound which is added for the purpose of preventing fog.
FR-A-1,450,841 describes silver halide emulsions chemically sensitized with N,N-dimethyl- selenourea, sodium thiosulphate and 4-hydroxy-6-methyl-1, 3,3a,7-tetraazaindene. US-A-3,442,653 describes silver halide emulsions chemically sensitized with potassium selenocyanate, benzotriazole methiodide and sodium thiosulphate. Neither mentions monodisperse emulsions.
It is therefore an object of this invention to provide a silver halide emulsion of which the sensitivity has sufficiently been enhanced by selenium sensitization and which has been improved in photographic fogging property and stability during storage, and does not cause any problem such as environmental pollution.
The present inventors have found that the above object can be accomplished by a silver halide emulison having monodispersed silver halide grains which have been selenium sensitized and sulfur sensitized simultaneously or separately in the presence of a nitrogen-containing heterocyclic compound capable of forming a complex with silver. The silver halide grains having a variation coefficient grain size distribution, as defined below, of 0.18 or less.
The present invention will be described in further detail below.
In the present invention, the above-mentioned silver halide grains which are selenium sensitized and sulfur sensitized simultaneously or separately in the presence of a nitrogen-containing heterocyclic compound are monodispersed silver halide grains.
The monodispersed silver halide grains in this invention refer to those which exhibit a variation coefficient of a grain size distribution of 0.18 or less when the emulsion is observed with an electron microscope photograph. Namely, when the standard deviation S of the grain size distribution is divided by the average grain size r, its value (variation coefficient) is 0.18 or less. The standard deviation S is calculated by the following formula:
The average grain size herein mentioned refers to an average value of diameters in the case of spherical silver halide grains or an average value of diameters of circular images calculated to be of the same area from the projected images in the case of cubic or other shapes than spheres, and r may be defined by the following formula, when individual grain sizes having such a meaning are represented by r, and their numbers by n :
The above grain sizes can be measured according to various methods generally employed in the related field of art for the above purpose. Representative methods are described in Rubland, "Grain Size Analytical Method", A.S. T.M. Symposium on light microscopy, 1955, pp. 94-122 or "Theory of Photographic Process" by Mieth & James, 3rd. edition, Chap. 2, published by Macmillan Co. (1966). This grain size can be measured by the use of the projected area of grains or approximate diameter values. When the grains are substantially of uniform shapes, the grain size distribution can be expressed with considerable accuracy as diameter or projected area.
The relation of the grain size distribution can be determined according to the method described in the essay by Triberi and Smith in "Empirical relation between the sensitometry distribution and grain size distribution in photographic emulsions", The Photographic Journal vol. LXXIX (1949), pp. 330-338.
The silver halide grains according to this invention have the variation coefficient of 0.18 or less as mentioned above, preferably monodispersed silver halide grains in the present invention are 0.15 or less. The silver halide grains, there may be composed of widely used materials such as silver chloride, silver bromide, silver chlorobromide, silver iodobromide and silver chloroiodobromide and preferably silver iodobromide which is suitable for high sensitization. As regards the shape of the silver halide grains, normal crystals such as hexahedron, octahedron and tetradecahedron are preferable, and normal cyrstals of octahedron crystal and tetradecahedron crystal are most preferable.
The silver halide emulsion having monodispersed silver halide grains according to this invention can be prepared by the use of methods described in P. Glafkides, "Chemie et Physique Photographique", published by Paul Montel Co., Ltd. (1967); G. F. Duffin, "Photographic Emulsion Chemistry", published by The Focal Press (1966); and V. L. Zelikman et al., "Making and Coating Photographic Emulsion", published by The Focal Press (1964). That is to say, the silver halide emulsion may be prepared by an acidic method, a neutral method and an ammoniacal method, and as method for reacting a soluble silver salt with a soluble halogen salt, an injection mixing process, a simultaneous mixing process or a combination thereof may be employed.
The emulsion having monodispersed silver halide grains according to this invention obtained by the above-mentioned preparation method is, in accordance with this invention as mentioned above, selenium sensitized and sulfur sensitized in the presence of the nitrogen-containing heterocyclic compound which is capable of forming a complex with silver.
In the nitrogen-containing heterocyclic compounds used in the present invention, examples of heterocyclic rings include a pyrazole ring, pyrimidine ring, 1,2,4-triazole ring, 1,2,3-triazole ring, 1,3,4-thiadiazole ring, 1,2,3-thiadiazole ring, 1,2,4-thiadiazole ring, 1,2,5-thiadiazole ring, 1,2,3,4-tetrazole ring, pyridiazine ring, 1,2,3-triazine ring, 1,2,4-triazine ring, 13,5-triazine ring, benzotriazole ring, benzimidazole ring, benzothiazole ring, quinoline ring, benzoxazole ring, benzoselenazole ring, naphthothiazole ring, naphthoimidazole ring, rhodanine ring, thiohydantoin ring, oxazole ring, thiazole ring, oxadiazole ring, selenadiazole ring, naphthoxazole ring, oxazolidinedione ring, thriazolotriazole ring, azaindene ring such as diazaindene ring, triazaindene ring, tetrazaindene ring, and pentazaindene ring, phthalazine ring and indazole ring.
Preferred compounds among the above are the compounds having the azaindene ring, and more preferably, the azaindene compounds having hydroxy groups as substituent groups such as hydroxytri- azaindene, hydroxytetrazaindene and hydroxypentazaindene compounds.
The heterocyclic rings may have substituent groups other than hydroxy group. Examples of other substituent groups include an alkyl group, an alkylthio group, an amino group, a hydroxyamino group, an alkylamino group, a dialkylamino group, an arylamino group, a carboxy group, an alkoxycarbonyl group, a halogen atom, an acylamino group, a cyano group and a mercapto group.
Examples of the nitrogen-containing compounds according to this invention are as follows, but the invention is not limited to the examples below:

(N-1) 2,4-Dihydroxy-6-methyl-1,3a,7-triazaindene
(N-2) 2,5-Dimethyl-7-hydroxy-1,4,7a-triazaindene
(N-3) 5-Amino-7-hydroxy-2-methyl-1,4,7a-triazaindene
(N-4) 4-Hydroxy-6-methyl-1,3,3a,7-tetrazaindene
(N-5) 4-Hydroxy-1,3,3a,7-tetrazaindene
(N-6) 4-Hydroxy-6-phenyl-1,3,3a,7-tetrazaindene
(N-7) 4-Methyl-6-hydroxy-1,3,3a,7-tetrazaindene
(N-8) 2,6-Dimethyl-4-hydroxy-1,3,3a,7-tetrazaindene
(N-9) 4-Hydroxy-5-ethyl-6-methyl-1,3,3a,7-tetrazaindene
(N-10) 2,6-Dimethyl-4-hydroxy-5-ethyl-1,3,3a,7-tetrazaindene
(N-11) 4-Hydroxy-5,6-dimethyl-1,3,3a,7-tetrazaindene
(N―12) 2,5,6-Trimethyl-4-hydroxy-1,3,3a,7-tetrazaindene
(N―13) 2-Methyl-4-hydroxy-6-phenyl-1,3,3a,7-tetrazaindene
(N-14) 4-Hydroxy-6-methyl-1,2,3a,7-tetrazaindene
(N―15) 4-Hydroxy-6-ethyl-1,2,3a,7-tetrazaindene
(N-16) 4-Hydroxy-6-phenyl-1,2,3a,7-tetrazaindene
(N-17) 4-Hydroxy-1,2,3a,7-tetrazaindene
(N-18) 4-Methyl-6-hydroxy-1 ,2,3a,7-tetrazaindene
(N-19) 7-Hydroxy-5-methyl-1,2,3,4,6-pentazaindene
(N-20) 5-Hydroxy-7-methyl-1,2,3,4,6-pentazaindene
(N-21) 5,7-Dihydroxy-1,2,3,4,6-pentazaindene
(N-22) 7-Hydroxy-5-methyl-2-phenyl-1,2,3,4,6-pentazaindene
(N-23) 5-Dimethylamino-7-hydroxy-2-phenyl-1,2,3,4,6-pentazaindene
(N-24) 1-Phenyl-5-mercaptoo-1,2,3,4-tetrazole
(N-25) 6-Aminopurine
(N-26) Benzotriazole
(N-27) 6-Nitrobenzimidazole
(N-28) 3-Ethyl-2-methylbenzothiazolium-p-toluene sulfonate
(N-29) 1-Methylquinoline
(N-30) Benzothiazole
(N-31) Benzoxazole
(N-32) Benzoselenazole
(N-33) Benzimidazole
(N-34) Naphthothiazole
(N-35) Naphthoselenazole
(N-36) Naphthoimidazole
(N-37) Rhodanine
(N-38) 2-Thiohydantoin
(N-39) 2-Thio-2,4-thioxazolidinedione
(N-40) 3-Benzyl-2-mercaptobenzimidazole
(N-41) 2-Mercapto-1-methylbenzothiazole
(N-42) 5-(m-Nitrophenyl)tetrazole
(N-43) 2,4-Dimethylthiazole
(N-44) 1-Methyl-5-ethoxybenzothiazoJe
(N-45) 2-Methyl-p-naphthotiazole
(N-46) 1-Ethyl-5-mercaptotetrazole
(N-47) 5-Methylbenzotriazole
(N-48) 5-Phenyltetrazole
(N-49) 1-Methyl-2-mercapto-5-benzoylamino-1,3,5-triazole
(N-50) 1-Benzoyl-2-mercapto-5-acetylamino-1,3,5-triazole
(N-51) 2-Mercapto-3-aryl-4-methyl-6-hydroxypyrimidine
(N-52) 2,4-Diemthyloxazole
(N-53) 1-Methyl-5-phenoxybenzoxazole
(N-54) 2-Ethyl-p-naphthoxazole
(N-55) 2-Mercapto-5-aminothiadiazole
(N-56) 2-Mercapto-5-aminoxadiazole
(N-57) 2-Mercapto-5-aminoselenadiazole

The amount of the nitrogen-containing heterocyclic compound to be added varies extensively in compliance with for instance, the size of the emulsion, composition and ripening condition but the compound is added in an amount of 10 mg to 1000 mg, preferably 50 mg to 200 mg per mole of silver halide, and is preferably to be added to such an amount as to enable the formation of from a single molecular layer to 10 molecular layers on the surface of each silver halide grain. This amount can be adjusted by the control of the adsorption equilibrium condition in accordance with the variation of pH and/ or temperature at the time of ripening.
The said compound can be added to the emulsion in the form of a solution dissolved in a suitable solvent (e.g., water or an aqueous alkaline solution) which has no harmful influence on the photographic emulsion. Said compound must be present at the time of the selenium sensitization and sulfur sensitization, and it is preferred that the compound is added thereto at the time of on or before the addition of a selenium sensitizer and sulfur sensitizer. Thus the compound may be added during chemical ripening by the selenium sensitizer and sulfur sensitizer, but addition before the chemical ripening is most preferable.
Next, the monodispersed silver halide grains according to this invention are selenium sensitized and sulfur sensitized in the presence of the above-mentioned nitrogen-containing heterocyclic compound. Examples of the selenium sensitizer used in the present invention include aliphatic isoselenocyanates such as allyl isoselenocyanate, selenoureas, selenoketones, selenoamides, selenocaboxylic acids, selenocarboxylates, selenophosphates and selenides such as diethylselenide and diethyldiselenide, which are described in US-A-1,574,944; 1,602,592 and 1,623,499.
While a wide variety of selenium sensitizers as described in each of the above publications, may be used it is preferred to use a labile type selenium compound rather than a non-labile type selenium compound such as selenious acid and a selenocyanic acid salt.
The term "labile" has a meaning well-known to the art and "a labile substance" is specifically an appellation for a substance which forms a silver salt when added to an aqueous solution of silver nitrate. For instance, a labile sulfur or selenium compound forms silver sulfate or silver selenide, respectively, when added to an aqueous silver nitrate.
The selenium sensitizer used in this invention also includes a wide range of labile selenium sensitizers, and the description in US-A-1,623,499; 1,574,944 and 1,602,592 may be referred thereto.
Preferred examples of the selenium sensitizers used in this invention include, for instance, collodial selenium metals and aliphatic isoselenocyanates and particularly useful selenium sensitizers include compounds having aliphatic groups as substituent groups, such as methylselenourea, ethylselenourea, propylselenourea, isopropylselenourea, butylselenourea, selenoketones, e.g. selenoacetone and seleno- acetophenone, selenoamides and selenocarboxylic acids, and also compounds which are substituted by aromatic groups or heterocyclic groups such as phenylselenourea, benzothiazolylselenourea and pyridyl- selenourea. In this invention, in addition to the labile organic selenium compounds as mentioned above, there may also be employed other useful selenium sensitizers having a labile selenium atom. Examples of the useful selenium sensitizers include tetramethylselenourea, N-(a-carboxyethyl)-N',N'-dimethyl- selenourea, selenoacetamide, diethylselenide, 2-selenopropionic acid, 3-selenobutyric acid, methyl-3- selenobutyrate and tri-p-tolylselenophosphate.
Of these kinds of selenium sensitizers, selenourea derivatives are particularly preferrred. The amount of these selenium sensitizers varies under various conditions such as the kind of selenium sensitizer used, the characteristics of the silver halide and ripening conditions, but is generally 2.0 x 10-³ to 10 mg, preferably 2.0 x 10-² to 1.0 mg, more preferably 0.1 to 0.5 mg per mole of the silver halide.
The monodispersed silver halide grains according to this invention are subjected to sulfur sensitization together with the above selenium sensitization.
In this invention, known types of sulfur sensitizers can be used in the above sulfur sensitization. Examples of the sulfur sensitizer include thiosulfate, allylthiocarbamidothiourea, allylisothiocyanate, cystin, p-toluenethiosulfonate and rhodanine. There can also be employed sulfur sensitizers which are disclosed in US-A-1,574944; 2,410,689; 2,278,947; 2,728,668; 3,501,313 and 3,656,955; DE-A-1,422,869; and JA-8-24937/1981 and 45016/1980. The amount of the sulfur sensitizer is such that it effectively increases the sensitivity of the emulsion. This amount varies over a fairly extensive range under various conditions such as the amount of nitrogen-containing heterocyclic compound used, the pH, the temperature and the size of the silver halide grains, but about 0.01 to 100 mg, preferably 0.1 to 10 mg per mole of silver halide is used, as a standard. The above selenium sensitizer and sulfur sensitizer are added as aqueous solutions at a time during the chemical ripening of the emulsion having monodispersed silver halide grains in accordance with the present invention. These sensitizers may be added individually, but simultaneous addition of both sensitizers is preferable. Thus, the silver halide emulsion (hereinafter referred to as the emulsion of this invention), has monodispersed silver halide grains which are selenium sensitized and sulfur sensitized in the presence of the nitrogen-containing heterocyclic compounds which are capable of forming a complex with silver.
In this invention, effective sensitization can be obtained by further carrying out a gold sensitization.
As the gold sensitizers used in this invention, a variety of gold compounds inclusive of ones having oxidation numbers of +1 or +3 can be employed. Typical examples of the gold sensitizers include chloroaurate, potassium chloroaurate, auric trichloride, potassium auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium aurothiocyanate and pyridyltrichlorogold.
The amount of the gold sensitizer is preferably within the range of about 0.01 to 10 mg, preferably 1.5 x 10-² to 4 mg per mole of silver halide as a standard, though varying with various conditions.
The gold sensitizer may be added to the emulsion of this invention as an aqueous solution. The gold sensitizer is preferably used simultaneously with the addition of the selenium sensitizer and the sulfur sensitizer, but may be added individually.
In this invention, the selenium sensitization and sulfur sensitization and the gold sensitization may preferably be carried out in the presence of a solvent for silver halide.
The solvents for silver halide used in this invention include

(a) organic thioethers as described in US-A-3,271,157; 3,531,289 and 3,574,628; and JA-B-1019/ 1979 and 158917/1979;
(b) thiourea derivatives as described in JA-B-82408/1978; 77737/1980 and 2982/1980;
(c) solvents for a silver halide having a thiocarbonyl group sandwiched between an oxygen atom or a sulfur atom and a nitrogen atom as described in JA-B-144319/1978;
(d) imidazoles as described in JA-B-100717/1979;
(e) sulfites;
(f) thiocyanates and the like.

Specific compounds will be given below:
An amount of the solvent for silver halide used for the emulsion of this invention may, in the case of, for example, a thiocyanate, range from 10 to 1000 mg, preferably 50 to 200 mg per mole of silver halide. The solvent for the silver halide may be added to the emulsion so as to be present when the selenium sensitization and the sulfur sensitization is carried out, but addition before the chemical ripening is preferable as with the aforesaid nitrogen-containing heterocyclic compound according to this invention.
In this invention, it is further possible to employ a reduction sensitization as well. Usable reducing agents are not particularly limited, but their examples include known stannous chloride, thiourea dioxide, hydrazine derivatives and silane compounds.
It is preferred that the reduction sensitization is carried out while the silver halide grains grow or after the selenium sensitization, sulfur sensitization and gold sensitization have been completed.
As described in detail above, the emulsion having the monodispersed silver halide grains of this invention which is selenium sensitized and sulfur sensitized in the presence of the aforesaid nitrogen-containing heterocyclic compound, or further gold sensitized and sensitized in the presence of the solvents for silver halide is endowed with extremely high sensitivity and has reduced occurrence of photographic fog. In the thus highly sensitized emulsion of this invention, when it constitutes an emulsion layer of a light-sensitive material, the monodispersed silver halide grains can be used in admixture together with other silver halide grains. In these emulsion layers, the silver halide grains according to this invention may preferably represent 70% by weight or more of the total silver halide grains of the layer.
The silver halide emulsion of this invention can be subjected to spectral sensitization by adding sensitizing dyes. The addition of the sensitizing dyes can be carried out at the beginning of the chemical ripening (which is also called the second ripening) of the silver halide emulsion, or during the ripening, or after the completion of the ripening, or at a suitable time prior to the coating operation of the emulsion.
Adding the sensitizing dyes to the aforesaid photographic emulsion can be accomplished in a variety of manners which have heretofore been suggested. For example, a method described in US-A-3,469,987 may be employed in which the sensitizing dyes are first dissolved in a volatile organic solvent, the resulting solution is dispersed in a hydrophilic colloid, and the thus prepared dispersion is added to the emulsion. With regard to the solvents for the sensitizing dyes, water-soluble organic solvents such as methyl alcohol, ethyl alcohol and acetone can be preferably used. The amount of each sensitizing dye is within the range of 1 x 10-⁵ mole to 2.5 x 10-² mole, preferably 1.0 x 10-⁴ mole to 1.0 x 10-³ mole per mole of the silver halide.
For the purpose of preventing the occurrence of photographic fog during the manufacturing process, storage or a developing treatment, and stabilizing photographic properties, a variety of compounds may be added to the silver halide grains at the time of or after completion of the chemical ripening.
Antifoggants and stabilizers which can be used for the aforesaid purposes include many known compounds, for example, azoles such as benzothiazolium salts, nitroindazoles, nitrobenzimdazoles, chloro- benzimidazoles, bromobenzimidazols, mercaptothiazoles, mercaptobenzimidazols, aminotriazoles, benzotriazoles, nitrobenzotriazoles, mercaptotetrazoles (particularly 1-phenyl-5-mercaptotetrazole), mercaptopyrimidines, mercaptotriazines, thioketo compounds such as oxazolinethione, and also benzenethiosulfinic acid, benzenesulfinic acid, benzenesulfonamide, hydroquinone derivatives, aminophenol derivatives, gallic acid derivatives and ascorbic acid derivatives. These additives are preferably added during the chemical ripening or before the coating process.
As a binder employed for the silver halide emulsion of this invention, a variety of hydrophilic colloids can be employed in addition to gelatins. The gelatins include not only gelatin but also gelatin derivatives. As the gelatin derivatives, there may be included, for instance, reaction products of gelatin and an acid anhydride, reaction products of gelatin and an isocyanate, and reaction products of gelatin and a compound having an active halogen atom. The above-mentioned acid anhydrides used in these reactions with the gelatin include, for example, maleic anhydride, phthalic anhydride, benzoic anhydride, acetic anhydride, isatoic anhydride and succinic anhydride and the above-mentioned isocyanate compounds include, for example, phenyl isocyanate, p-bromophenyl isocyanate, p-chlorophenyl isocyanate, p-tolyl isocyanate, p-nitrophenyl isocyanate and naphthyl isocyanate.
As the hydrophilic colloids used to prepare the silver halide emulsion, besides the above-mentioned gelatin derivatives and conventional gelatins for photography, there can be used, if desired, colloidal albumin, agar, gum arabic, dextran, alginic acid, cellulose derivatives such as cellulose acetates which have been hydrolysed until the acetyl content get to a level of 19 to 26%, polycrylamide, imido group-containing polyacrylamides, casein, vinyl alcohol polymers containing urethane carboxyl groups or cyanoacetyl groups such as vinyl alcohol-vinyl cyanoacetate copolymer, polyvinyl alcohol-polyvinyl pyrrolidones, hydrolized polyvinyl acetates, polymers obtained by polymerization of proteins or acyl saturated proteins with monomers having vinyl groups, polyvinylpyridines, polyvinylamines, polyaminoethyl methacrylates and polyethylene imines.
For various purposes such as coating aid, antistatic slide improvement, emulsion dispersion, adhesion prevention and improvement of photographic properties (e.g., development acceleration, high contrast and sensitization), a vareity of known surface active agents may be included in the silver halide emulsion of this invention.
These surface active agents are described, for example, in US-A-2,240,472; 2,831,766; 3,158,484; 3,210,191; 3,294,540 and 3,507,660; GB-B-1,012,495; 1,022,878; 1,179,290 and 1,198,450; US-A-2,739,891; 2,823,123; 1,179,290; 1,198,450; 2,739,891; 3,068,101; 3,415,649; 3,666,478 and 3,756,828; GB-B-1,397,218; US―A―3,113,816; 3,411,413; 3,473,174; 3,345,974; 3,726,683 and 3,843,368; BE-A-731,126; GB-B-1,138,514; 1,159,825 and 1,374,780; US-A-2,271,623; 2,288,226; 2,944,900; 3,235,919; 3,671,247; 3,772,021; 3,589,906; 3,666,478 and 3,754,924; DE-A-1,961,683; JA-B-117414/1975 and 59025/1975; and JA-B-378/1965; 379/1965 and 13822/1968. There can be used nonionic surface active agents, for example saponin (steroid series), alkyleneoxide derivatives such as polyethylene glycol, condensates of polyethylene glycol/polypropylene glycol, polyethylene glycol alkyl- or alkylaryl-ether polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkyleneglycol alkylamines or amides and polyethylene oxide additives of silicones, glycidol derivatives such as alkenyl succinic acid polyglyceride and alkylphenol polyglyceride, fatty acid esters of polyvalent alcohols, alkylesters of sugar, urethanes or ethers of the sugar, etc.; anionic surface active agents having an acidic group (e.g. a carboxy group, sulfo group, phospo group, sulfuric ester group, phophoric ester groupe) such as tri- erpenoid seires saponin, alkylcarboxylic acid salts, alkylnaphthalene sulfonic acid salts, alkylsulfuric esters, alkyl phosphoric esters, N-acyl-N-alkyltaurines, sulfosuccinic acid esters, sulfoalkyl polyoxythylene alkylphenyl ethers and polyoxyethylene alklphosphoric acid esters; amphoteric surface active agents such as amino acids, aminoalkyl sulfonic acids, aminoalkylsulfuric acid ester or phosphoric acid esters, alkyl- betaines, amineimides and amineoxides; and cationic surface active agents such as alkylamine salts, aliphatic or aromatic quaternary ammonium salts; heterocyclic (e.g. pyridinium, imidazolium) quaternary ammonium salts, and sulfonium compounds containing aliphatic or heterocyclic ring for sulfonium salts.
In the silver halide emulsion of this invention, they may include, as development accelerators, in addition to the above-mentioned surfactants, imidazoles, thioethers and selenoethers described in DE-A-2,002,871; 2,445,611 and 2,360,878; and GB-A-1,352,196.
When the silver halide emulsion of this invention is used as a color light-sensitive material, the usual technqiues and materials for the color light-sensitive material can be employed. That is to say, a yellow coupler, a magenta coupler and cyan coupler are each combinedly added to the blue-sensitive silver halide emulsion, the green-sensitive silver halide emulsion and the red-sensitive silver halide emulsion. It is preferred that these couplers have hydrophobic groups called ballast groups and are non-diffusible. Each coupler may be either tetraequivalent or diequivalent to a silver ion. Further, a colored coupler having the effect of color correction or a coupler (so-called DIR coupler) for giving off development restrainers during the development process may be included in the emulsion.
Furthermore, the coupler above may be a coupler by the use of which a product of a coupling reaction will become colorless.
As yellow couplers, known open chain ketomethylene couplers can be employed. Among them, benzoylacetoanilide and pivaloylacetoanilide series compounds are advantageous. Examples of these usable yellow couplers are disclosed in US-A-2,875,057; 3,265,506; 2,408,194; 3,551,155; 3,582,322; 3,725,072 and 3,891,445; DE-B-1,547,868; DE-A-2,213,461, 2,219,917; 2,261,361; 2,414,006 and 2,263,875. Particularly preferable yellow couplers are as follows:
As magenta color forming couples, there can be employed pyrazolone compounds, indazolone compounds and cyanoacetyl compounds. The pyrazolone compounds are particularly advantageous. Examples of the usable megenta color forming couplers are disclosed in US-A-2,600,788; 3,062,653; 3,408,194 and 3,519,429; JA-B-111631/1974; 28236/1981 and 94752/1982; and JA-B-27930/1973. Particularly preferable couplers include following compounds.
(12) Polymer coupler latex in which the above-mentioned magenta coupler (2) is impregnated into the latex which comprises the copolymer of 1-(2,4,6-trichlorophenyl)-3-(3-acrylamidobenzamide)-4-pyrazoryl-5-oxo-2-pyrazoline and n-butyl acrylate in the ratio of 20:80.
As cyan color forming couplers, there can be employed phenol type compounds, naphthol type compounds and the like. Examples of the cyan color forming couplers are those described in US―A―2,423,730; 2,474,293 and 2,895,826; JA-B-117422/1975; and JA-B-127513. Particularly preferable cyan color forming couplers include following compounds.
A colored magenta couplers, examples thereof are described in US-A-2,801,171 and 3,519,429; and JA-B-27930/1973. Particularly preferable colored magneta couplers include following compounds.
As colored cyan couplers, examples thereof are described in US-A-1,084,480; and JA-B-32461/ 1980. Particularly preferable colored cyan couplers include following compounds. (1)
The above-mentioned various couplers may be included in a combination of two or more couplers in a single layer, or the same coupler may be included in more than two different layers.
Incorporation of the coupler into a silver halide emulsion layer can be carried out in a known way, for instance, in the way described in U.S.-A-2,322,027. For instance, the coupler is dissolved in an appropriate organic solvent, and then dispersed in a hydrophilic colloidal solution. Examples of the appropriate organic solvent include a phthalic acid alkyl ester such as dibutyl phthalate and dioctyl phthalate, a phosphoric acid ester such as diphenyl phosphate, triphenyl phosphate, tricresyl phosphate and dioctyl butyl phosphate, a critic acid ester such as tributyl acetylcitrate, a benzoic acid ester such as octyl benzoate and an alkyl amide such as diethyllaurylamide. Examples of other types of the appropriate organic solvent include organic solvents having boiling points in the range of about 30°C to 150°C, for instance, a lower alkyl acetate such as ethyl acetate and butyl acetate, ethyl propionate, sec-butyl alcohol, methyl isobutyl ketone, β-ethoxyethyl acetate and methyl cellosolve acetate. The above-mentioned high- boiling point solvent and low-boiling point solvent may be employed in combination.
If a coupler contains an acidic group such as carboxylic acid or sulfonic acid, it can be incorporated into a hydrophilic colloidal solution in the form of an aqueous alkaline solution.
The coupler is incorporated into an emulsion layer generally in an amount from 2 x 10-³ to 5 x 10-¹ mole, preferably from 1 x 10-² to 5 x 10-¹ mole per mole of silver in the silver halide emulsion layer.
Furthermore, the light-sensitive material according to this invention may contain a DIR compound. Examples of the DIR compounds are those described in U.S.-A-2,327,554; 3,227,554 and 3,615,506; JA-B-82424/1977; 145135/1979 and 151944/1982; and JA-B-16141/1976. Particularly preferable DIR compounds include the following compounds.
Moreover, examples of stain preventive agents effectively usable in the emulsion of this invention, are described in U.S.-A-2,728,659; and JA-B-2128/1971. Particularly preferable stain preventive agents include the following compounds.
As antistatic agents to be used in the emulsion of this invention, there may be effectively employed diacetyl cellulose, styrene-perfluoroalkyllithium maleate copolymer, an alkali salt of a reaction product between styrene-maleic anhydride copolymer and p-aminobenzenesulfonic acid. Illustrative of matting agents are polymethyl methacrylate, polystyrene and alkali-soluble polymers. Further, it is also possible to use a colloidal silicon oxide. Also, as latexes to be added for improvement of the film properties, there may be employed copolymers of, for instance, an acrylic acid ester or vinyl ester, with other monomers having ethylenic groups. Gelatin plasticizers may be exemplified by glycerine and glycol type compounds, and thickeners may include for instance, styrene-sodium maleate copolymer and alkyl vinyl ether-maleic acid copolymer.
As the support for the light-sensitive material comprising the emulsion of this invention as prepared above, there may be employed, for example, baryta paper, polyethylene-coated paper, polypropylene synthetic paper, glass paper, cellulose acetate, cellulose nitrate, polyvinyl acetal, polypropylene, polyester film such as of polyethyleneterephthalate and polystyrene. These supports may be chosen suitably depending on the purpose of use of the respective light-sensitive silver halide photographic material.
These supports may be applied with subbing treatment, if necessary.
The light-sensitive material prepared by the use of the emulsion of this invention may be subjected to light exposure and then developed according to the known method conventionally used.
The black-and-white developer is an alkaline solution containing developing agents such as hydroxy benzenes, aminophenols or aminobenzenes, and it may further contain alkali metal salts such as a sulfite, a carbonate, a bisulfite, a bromide and an iodide. When said light-sensitive material is for color photography, it may be developed by a color developing process which is commonly used. In a reversal process, it is firstly developed by a developer for a black-and-white negative and then subjected to white color exposure, or subjected to treatment in a bath containing an antifoggant, and further developed for color development in an alkaline developing solution containing color developing agents.
There is no particular restriction to the method for treatment, and any method may be applied. As a typical example there may be mentioned a system in which bleach-fix treatment is conducted after the color development and further washing and stabilizing treatments are carried out as the case requires, or a system in which the bleaching and the fixing are separately carried out after the color development, and further washing and stabilizing treatments are carried out as the case requires.
The aforementioned silver halide photographic emulsion can particularly preferably be used for color photography and can suitably be applied to many light-sensitive materials because it has a noticeably high photographic sensitivity and reduced photographic fog. For example, the light-sensitive material according to this invention can be applied effectively to a variety of uses in a black-and-white generic photography, X-ray photography, color photography, infrared photography, microphotography, silver dye bleach, reversal process and diffusion transfer process.
This invention is illustrated in detail by referring to the following Examples, which the embodiments of this invention.

Example 1

To a green-sensitive high sensitivity silver iodobromide gelatin emulsion comprising silver halide grains of monodispersed cubic crystals each having a grain size of 1.6 Ilm, and a silver iodide content of 2 mole % and a variation coefficient of a grain size distribution of 12%, various kinds of sensitizers are added in amounts as shown in the following Table 1 per mole of silver halide in the presence of a hydroxy tetrazaindene compound as a nitrogen-containing heterocyclic compound according to this invention and ammonium thiocyanate as a solvent for silver halide, and then subjected to chemical ripening at 55°C for 50 minutes. After completion of the chemical ripening, to the aforesaid emulsion were added a magenta coupler dispersion as shown below and a film hardner, and the thus prepared emulsions were applied onto cellulose triacetate base supports and were dried.

(Magenta coupler)

Next, the samples were subjected to 1/50 second's Wedge exposure through a green filter (produced by Tokyo Shibaura K. K.) by the use of a KS-1 type photosensitometer (produced by Konishiroku Photo Industry Co., Ltd.), and a color negative development was carried out in accordance with the undermentioned conditions.
Compositions of the processing solutions used in the respective processing steps were as follows:
(make up to one liter with addition of water and adjust to pH 6.0 by using an aqueous ammonia solution)
For the resulting dye images, density measurement was carried out through a green filter to obtain green light sensitivities and photographic fogs. Obtained results as shown in Table 1 below. Each sensitivity was expressed by normalizing an inverse number of exposure necessary to provide an optical density of a fog plus 0.1, and assuming the sensitivity of Sample No. 1 as 100.
As is clear from Table 1 above, it can be understood that, in Samples 2, 3 and 4 according to this invention, sensitivities thereof are high and the occurrence of photographic fog has been reduced, whereas, in Samples 1 and 5 which are outside the present invention, high sensitivity could not be attained or photographic fog was increased if high sensitivity was attained.

Example 2

An emulsion was prepared in the same manner as in Example 1 except that a green-sensitive high sensitivity silver iodobromide gelatin emulsion comprising silver halide grains of monodispersed octahedral crystals each having a grain size of 1.6 µm, and a silver iodide iodide content of 2 mole % and a variation coefficient of a grain size distribution of 12% is used. With respect to a Sample which was obtained by applying the resulting emulsion onto a support, a treatment for development was conducted in the same manner as in Example 1. The results obtained by the measurement of the photographic properties are shown in the Table 2 below.
This example was to accomplish the same sensitization as in Example 1 by using a monodispersed emulsion having octahedral crystals in place of the monodispersed emulsion having cubic crystals used in Example 1. As understood from Table 2, Samples 7, 8 and 9 according to this invention showed the same excellent sensitization effects as in Example 1, and high sensitization could be accomplished.

Example 3

An emulsion was prepared in the same manner as in Example 1 except that a green-sensitive high sensitivity silver iodobromide gelatin emulsion comprising silver halide grains of monodispersed tetradecahedral crystals each having a grain size of 1.6 pm, and a silver iodide content of 2 mole % and a variation coefficient of a grain size distribution of 12% is used. With respect to a Sample which was obtained by applying the resulting emulsion onto a support, a treatment for development was conducted in the same manner as in Example 1. The results obtained by the measurement of the photographic properties are shown in the Table 3 below.
This example was to accomplish the same sensitization as in Example 2 by using a monodispersed emulsion having tetradecahedral crystals in place of the monodispersed emulsion having octahedral crystals in Example 2. As understood from Table 3, Samples 12, 13 and 14 according to this invention showed the same excellent sensitization effects as in Example 2, and high sensitization could be accomplished.
The silver halide emulsion having monodispersed silver halide grains which have been selenium sensitized and sulfur sensitized simultaneously or separately in the presence of a nitrogen-containing heterocyclic compound capable of forming a complex with silver does not cause photographic fog and can attain high sensitivity of a photographic material. Additional gold sensitization and incorporation of a solvent for silver halide would promote the high sensitization according to this invention.

Claims

1. A silver halide emulsion which comprises monodispersed silver halide grains which have been subjected to selenium sensitization and sulfur sensitization carried out simultaneously or separately in the presence of a nitrogen-containing heterocyclic compound capable of forming a complex with silver, characterised in that the silver halide grains have a variation coefficient of grain size distribution, i.e. the- relationship s/r, of 0.18 or less, wherein

in which S is the standard deviation, r is the average grains size, r, is the individual grain size, and n_; is the number of grains of size r,.

2. A silver halide emulsion according to Claim 1, wherein the nitrogen-containing heterocyclic compound includes a heterocyclic ring selected from pyrazole, pyrimidine, 1,2,4-triazole, 1,2,3-triazole, 1,2,3-thiadiazole, 1,2,4,-thiadiazole, 1,2,5-thiadiazole, 1,2,3,4-tetrazole, pyridazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, benzotriazole, benzimidazole, benzothiazole, quinoline, benzoxazole, benzoselenazole, naphthothiazole, naphthoimidazole, rhodanine, thiohydantoin, oxazole, thiazole, oxadiazole, selenadiazole, naphthoxazole, oxazolidinedione, triazolotriazole, azaindene, phthalazine and indazole rings.

3. A silver halide emulsion according to Claim 2, wherein the heterocyclic rings have a substituent selected from hydroxy, alkyl, alkylthio, amino, hydroxyamino, alkylamino, dialkylamino, acrylamino, carboxy group, alkoxy-carbonyl, halogen, acylamino, cyano and mercapto.

4. A silver halide emulsion according to any preceding claim, wherein the nitrogen-containing heterocyclic compound was present during sensitization in an amount of 10 mg to 1000 mg per mole of the silver halide.

5. A silver halide emulsion according to any preceding claim, wherein the monodispersed silver halide grains have a variation coefficient of the grain size distribution of 0.15 or less.

6. A silver halide emulsion according to any preceding claim, wherein at least one selenium sensitizer selected from aliphatic isoselenocyanates, selenoureas, selenoketones, selenoamides, selenocarboxylic acids, selenocarboxylates, selenophosphates, selenides, collodial selenium metals, aliphatic isoselenocyanates, selenoureas having an °aliphatic group or an aromatic group, selenoketones, selenoamides and selenocarboxylic acids was present during selenium sensitization.

7. A silver halide emulsion according to Claim 6, wherein the selenium sensitizer was present during selenium sensitization in an amount of 2.0 x 10-³ to 10 mg per mole of the silver halide.

8. A silver halide emulsion according to Claim 7, wherein the selenium sensitizer was present during selenium sensitization in an amount of 2.0 x 10-² mg to 1.0 per mole of the silver halide.

9. A silver halide emulsion according to any preceding claim, wherein at least one sulfur sensitizer selected from thiosulfate derivatives, thiourea derivatives, allylisothiocyanate, cystin, p-toluenethiosulfonate and rhodanine was present during sulfur sensitization.

10. A silver halide emulsion according to Claim 9, wherein the sulfur sensitizer was present during sulfur sensitization in an amount of 0.01 to 100 mg per mole of the silver halide.

11. A silver halide emulsion according to Claim 10, wherein the sulfur sensitizer was present during sulfur sensitization in an amount of 0.1 to 10 mg per mole of the silver halide.

12. A silver halide emulsion according to any preceding claim wherein the silver halide grains have been subjected to gold sensitization.

13. A silver halide emulsion according to any preceding claim, wherein at least one gold sensitizer selected from chloroaurate, potassium chloroaurate, auric trichloride, potassium auric thiocyanate, potassium iodoaurate, tetracyanoauric acid, ammonium aurothiocyanate and pyridyltrichlorogold was present during gold sensitization.

14. A silver halide emulsion according to any preceding claim, wherein a solvent for silver halide was present during the selenium sensitization and sulfur sensitization.

15. A silver halide emulsion according to Claim 14, wherein the solvent for silver halide is selected from organic thioethers, thiourea derivatives, solvents having a thiocarbonyl group sandwiched between an oxygen atom or a sulfur atom and a nitrogen atom, imidazoles, sulfites and thiocyanates.

16. A silver halide emulsion according to Claim 15, wherein the solvent for silver halide is a thiourea derivative or a thiocyanate.