DE68925676T2 - Silver halide photographic light-sensitive material - Google Patents

Description

The present invention relates to a silver halide photographic light-sensitive material, and more particularly to a silver halide photographic light-sensitive material having a high sensitivity and producing little fog and a high maximum image density. The present invention also relates to a silver halide photographic light-sensitive material having little change in sensitivity with time and fog during storage thereof.

The basic properties required of a photographic silver halide emulsion are high sensitivity, low fog and fine grains.

To increase the sensitivity of an emulsion, it is necessary to (1) increase the number of photons absorbed by a single grain; (2) increase the efficiency of converting photoelectrons generated by light absorption into a silver cluster (latent image); and (3) increase the development activity to effectively utilize the latent image formed. Increasing the grain size increases the number of photons absorbed per grain, but deteriorates the image quality. Increasing the development activity is an effective means for increasing sensitivity. However, in the case of parallel development such as color development, the grain state generally deteriorates by increasing the development activity. In order to increase sensitivity without deteriorating the grain state, it is particularly advantageous to increase the efficiency of converting photoelectrons into a latent image, that is, the quantum yield. In order to increase the quantum yield, inefficient processes such as recombination and latent image dispersion must be minimized. It is known that a reduction sensitization process to form a small silver nucleus without development activity inside or on the surface of a silver halide grain is effective in preventing recombination.

James et al discovered that the sensitivity can be increased with a lesser degree of fogging than in normal reduction sensitization by carrying out a type of reduction sensitization in which a coating film containing an emulsion subjected to gold plus sulfur sensitization is vacuum deaerated and then heat treated in a hydrogen atmosphere. This sensitization process is well known as hydrogen sensitization and is effective as a means of achieving high sensitivity on a laboratory scale. Hydrogen sensitization is practically used in the field of astrophotography.

The method of reduction sensitization has been studied for a long time. Carroll, Lowe et al and Fallens et al, in US Patents 2,487,850 and 2,512,925 and British Patent 789,823 found that a tin compound, a polyamine compound and a thiourea dioxide-based compound were effective as reduction sensitizers. Collier compares properties of silver nuclei formed by various reduction sensitization methods in Photographic Science and Engineering, Vol. 23, p. 113 (1979). She used dimethylaminoborane, stannous chloride, hydrazine and high pH, low pAg ripening methods. Reduction sensitization methods are also disclosed in U.S. Patents 2,518,698, 3,201,254, 3,411,917, 3,779,777 and 3,930,867. Not only the selection of a reduction sensitizer but also a method of using a reducing agent are disclosed in, for example, JP-B-57-33572 ("JP-B" means an examined Japanese patent application), JP-B-58-1410 and JP-A-57-179835 ("JP-A" means an unexamined published Japanese patent application). Techniques for improving the storage stability of an emulsion subjected to reduction sensitization are disclosed in JP-A-57-82831 and JP-A-60-178445. Despite the large number of investigations as described above, the increase in sensitivity is insufficient compared to that obtained in hydrogen sensitization, in which a photosensitive material is treated with hydrogen gas in a vacuum. This is reported by Moisar et al in "Journal of Imaging Science", vol. 29, p. 233 (1985).

As described above, the conventional reduction sensitization techniques are insufficient to meet the demand for a photographic light-sensitive material with high sensitivity and high image quality are still sufficient in recent times.

An object of the present invention is to provide a photographic light-sensitive material having high sensitivity and low fog.

Another object of this invention is to provide a silver halide photographic light-sensitive material having the above properties which produces a high maximum image density.

Still another object of the present invention is to provide a photographic light-sensitive material having little change in sensitivity and fog during storage with the passage of time.

In one aspect, the present invention provides a silver halide photographic light-sensitive material comprising a support having thereon at least one silver halide emulsion layer, said silver halide emulsion layer containing a monodisperse silver halide emulsion whose grains are of the core/shell type or double structure type having different silver halide compositions in their core and surface regions and which are reduction sensitized by ascorbic acid or an ascorbic acid derivative during the preparation of the silver halide emulsion, provided that the silver halide grains have less than 5 mol% silver iodide on their surface.

Preferably, the silver halide emulsion is a monodisperse silver halide emulsion which has been reduction sensitized in the presence of at least one type of thiosulfonic acid compounds having the following formulas (I), (II) and (III):

R-SO₂S-M (I)

R-SO₂S-R¹ (II)

RSO₂S-Lm-SSO₂-R² (III)

wherein R, R¹ and R² may be the same or different and represent an aliphatic group, an aromatic group or a heterocyclic group, M represents a cation, L represents a divalent linking group, m represents 0 or 1, compounds having the formulas (I) to (III) may be polymers containing as a basic unit divalent groups derived from compounds having the formulas (I) to (III), and, if possible, R, R¹, R² and L may be linked to each other to form a ring.

Compounds of formulae (I) to (III) may be polymers containing as a basic unit divalent groups derived from compounds of formulae (I) to (III) and, if possible, R, R¹, R² and L may be linked together to form a ring.

Preferably, the monodisperse silver halide emulsion is reduction sensitized in the presence of at least one type of thiosulfonic acid compounds having the formulas (I), (II) and (III) during precipitation of the silver halide grains.

The present invention will be described in detail below.

Processes for producing silver halide emulsions can be roughly divided into, for example, grain formation, desalting, chemical sensitization and coating steps. Grain formation is further divided into, for example, the sub-steps of nucleation, ripening and precipitation. These steps are sometimes not carried out in the order given above, but in reverse order, or repeated.

At least one type of compounds represented by formulas (I), (II) and (III) may be added at any step from grain formation to the coating process of a monodisperse silver halide emulsion. The compound is preferably added during the grain formation process of the silver halide grains, and more preferably during the precipitation of the grains. Particularly preferably, the reduction sensitization is carried out in the presence of the compound during the precipitation of the monodisperse silver halide grains. The reduction sensitization may be carried out at any time during nucleation as the initial stage of grain formation, physical ripening or precipitation. Although the reduction sensitization is normally carried out before the chemical sensitization (preferably gold plus sulfur sensitization), it may be carried out after the chemical sensitization if necessary. In the case of carrying out the chemical sensitization in addition to gold sensitization, the reduction sensitization is preferably carried out before the chemical Sensitization is carried out so as not to generate undesirable fog. Reduction sensitization is particularly preferably carried out during precipitation of the silver halide grains. In this case, "precipitation" means a state in which the silver halide grains are caused to grow and precipitate by physical ripening or addition of a water-soluble silver salt and a water-soluble alkali halide. The method of carrying out reduction sensitization during precipitation includes a method in which reduction sensitization is carried out while temporarily stopping the addition of the silver salt and alkali halide during precipitation and then continuing precipitation again.

A method of adding a reducing sensitizer is advantageous because the degree of reducing sensitization can be precisely adjusted.

The reduction sensitizer is used as a solution in water or a solvent, e.g. glycols, ketones, esters or amides, and the solution may be added during grain formation or before or after chemical sensitization. Although the reduction sensitizer may be added at any step of emulsion preparation, it is particularly preferably added during grain precipitation. The reduction sensitizer is preferably added at any time during grain formation, although it may also be initially added in a reaction vessel. In addition, the reduction sensitizer may be added in a aqueous solution of a water-soluble silver salt or a water-soluble alkali halide so that grain formation is carried out using the aqueous solution. A method of adding a solution of the reduction sensitizer several times or continuously adding it for a long time as grain formation progresses is also advantageous.

Thiosulfonic acid compounds represented by formulas (I), (II) and (III) are described in more detail below. When R, R¹ and R² each represent an aliphatic group, they are a saturated or unsaturated, straight-chain, branched or cyclic aliphatic hydrocarbon group, and preferably an alkyl group having 1 to 22 carbon atoms, or an alkenyl or alkynyl group having 2 to 22 carbon atoms. These groups may have a substituent group. Examples of alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, 2-ethylhexyl, decyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, isopropyl and t-butyl.

Examples of alkenyl groups are allyl and butenyl.

Examples of alkynyl groups are propargyl and butynyl.

An aromatic group in R, R¹ and R² includes an aromatic group with a single ring or a fused ring system. The aromatic group preferably contains 6 to 20 carbon atoms. Examples of such aromatic groups are phenyl and naphthyl. These groups may have substituents.

A heterocyclic group in R, R¹ and R² includes a 3- to 15-membered ring containing at least one element of nitrogen, oxygen, sulfur, selenium and tellurium, and at least one carbon atom. Examples of heterocyclic groups are pyrrolidine, piperidine, pyridine, tetrahydrofuran, thiophene, oxazole, thiazole, imidazole, benzothiazole, benzoxazole, benzimidazole, selenazole, benzoselenazole, tellurazole, triazole, benzotriazole, tetrazole, oxadiazole and thiadiazole rings. 3- to 6-membered rings are preferred.

Examples of substituent groups for R, R¹ and R² are an alkyl group (e.g. methyl, ethyl and hexyl), an alkoxy group (e.g. methoxy, ethoxy and octyloxy), an aryl group (e.g. phenyl, naphthyl and tolyl), a hydroxyl group, a halogen atom (e.g. fluorine, chlorine, bromine and iodine), an aryloxy group (e.g. phenoxy), an alkylthio group (e.g. methylthio and butylthio), an arylthio group (e.g. phenylthio), an acyl group (e.g. acetyl, propionyl, butyryl and valeryl), a sulfonyl group (e.g. methylsulfonyl and phenylsulfonyl), an acylamino group (e.g. acetylamino and benzoylamino), a sulfonylamino group (e.g. methanesulfonylamino and benzenesulfonylamino), an acyloxy group (e.g. acetoxy and benzoxy), carboxyl, cyano, sulfo, amino, -SO₂SM (M represents a monovalent cation), and -SO₂R¹.

A divalent linking group represented by L includes an atom or group of atoms containing at least one atom of C, N, S and O. Examples of L are alkylene, alkenylene, alkynylene, arylene, -O-, -S-, -NH-, -CO- and -SO₂-. These divalent Groups can be used individually or in combinations of two or more.

Preferably, L represents a divalent aliphatic or aromatic group. Examples of divalent aliphatic groups for L are -(CH₂)n- (n = 1 to 12), -CH₂-CH=CH-CH₂-, -CH₂C=-CCH₂-,

and xylylene. Examples of divalent aromatic groups for L are phenylene and naphthylene.

These linking groups may contain further substituent groups mentioned above.

M is preferably a metal ion, an ammonium ion or an organic cation. Examples of metal ions are lithium ions, sodium ions and potassium ions. Examples of organic cations are organic ammonium ions (e.g. tetramethylammonium and tetrabutylammonium), organic phosphonium ions (e.g. tetraphenylphosphonium) and guanidinium ions.

When a compound having any of the formulas (I) to (III) is a polymer, examples of its basic unit are as follows:

Any of the above polymers may be a homopolymer or a copolymer with another copolymerizable monomer.

Examples of a compound having formula (I), (II) or (III) are listed in Table A below. The compounds are, however, not limited to those in Table A.

Thiosulfonic acid compounds having formulas (I), (II) and (III) can be readily synthesized by methods described or cited in JP-A-54-1019; GB-PS 972 211; "Journal of Organic Chemistry", vol. 53, p. 396 (1988); and "Chemical Abstracts", vol. 59, 9776e.

A preferred addition amount of a compound of formula (I), (II) or (III) is 10⁻⁷ to 10⁻¹ mol per mol of silver halide. The addition amount is more preferably 10⁻⁷ to 10⁻², and particularly preferably 10⁻⁵ to 10⁻³ moles per mole of silver halide.

A conventional method for adding an additive in a photographic emulsion can be used to add the thiosulfonic acid compounds represented by formulas (I) to (III) in the manufacturing process. For example, a water-soluble compound can be added in the form of an aqueous solution of any concentration. A water-insoluble or sparingly water-soluble compound is dissolved in any organic solvent (such as alcohols, glycols, ketones, esters and amides) that is miscible with water and does not adversely affect the photographic properties and then added as a solution.

As described above, a compound having formula (I), (II) or (III) may be added at any time during the preparation process, e.g. during grain formation of a silver halide emulsion or before or after chemical sensitization. The compound is preferably added before or during reduction sensitization. The compound is particularly preferably added while the water-soluble silver salt and alkali halide are being added.

Although the compound may be added in advance to a reaction vessel, it is preferably added at any time during grain formation. In addition, a compound represented by formula (I), (II) or (III) may be added in an aqueous solution of a water-soluble silver salt or a water-soluble alkali halide to prepare a reaction vessel using the aqueous solution. to carry out grain formation. A method of repeatedly adding a solution of a compound of formula (I), (II) or (III), or of continuously adding it over a long period of time as grain formation progresses is also advantageous.

A thiosulfonic acid compound which is particularly preferred in the present invention is represented by formula (I).

Examples of ascorbic acid or its derivatives (hereinafter referred to as "ascorbic acid compound") are as follows:

(A-1) L-ascorbic acid

(A-2) Sodium L-ascorbate

(A-3) Potassium L-ascorbate

(A-4) DL-ascorbic acid

(A-5) Sodium D-ascorbate

(A-6) L-Ascorbyl-6-acetat

(A-7) L-Ascorbyl-6-palmitate

(A-8) L-Ascorbyl-6-benzoate

(A-9) L-Ascorbyl-5,6-diacetat

(A-10) L-ascorbyl-5,6-O-isopropylidene.

To add the above ascorbic acid compounds in a process of preparing a silver halide emulsion according to the present invention, they may be directly dispersed in an emulsion. Alternatively, the ascorbic acid compound may be dissolved in a single solvent or a solvent mixture of, for example, water, methanol and ethanol and then added during the preparation process.

It is advantageous that the ascorbic acid compound of the present invention is added in a much larger amount than the preferred addition amount of a conventional reducing sensitizer. For example, JP-B-57-33572 describes "the amount of a reducing agent does not normally exceed 0.75 x 10-2 meq (8 x 10-4 mol/AgX mol) per gram of silver ion. An amount of 0.1 to 10 mg (10-7 to 10-5 mol/AgX mol for ascorbic acid) per kg of silver nitrate is effective in many cases" (reduced values were calculated by the inventors). U.S. Patent No. 2,487,850 describes that "a tin compound as a reduction sensitizer can be added in an addition amount of 1 x 10-7 to 44 x 10-6 mol." JP-A-57-179835 describes that it is sufficient to add about 0.01 to about 2 mg of thiourea dioxide or about 0.01 mg to about 3 mg of tin chloride per mol of silver halide. A preferable addition amount of the ascorbic acid compound used in the present invention depends on factors such as grain size and halogen composition of an emulsion, emulsion preparation temperature, pH and pAg. However, the addition amount is preferably within a range of 5 x 10-5 to 10-10 mol. to 1 x 10⊃min;1 mol, more preferably 5 x 10⊃min;⊃min; mol to 1 x 10⊃min;2 mol, and particularly preferably 1 x 10⊃min;3 to 1 x 10⊃min;2 mol per mol of silver halide.

Although the ascorbic acid compound of the present invention can be added at any time in an emulsion preparation process, it is particularly preferably added during grain precipitation. The ascorbic acid compound is preferably at any time during grain formation, although it may be added to the reaction vessel in advance. In addition, the ascorbic acid compound may be added in an aqueous solution of a water-soluble silver salt or a water-soluble alkali halide to carry out grain formation using this aqueous solution. A method of adding a solution of the ascorbic acid compound several times or continuously adding it over a long period of time as grain precipitation progresses is also preferred.

The method of carrying out reduction sensitization using the ascorbic acid compound according to the present invention is superior to a conventional reduction sensitization method in sensitivity, fog and storage stability. However, depending on other conditions, it is sometimes more preferable to use the ascorbic acid compound with another reduction sensitization method. In this case, however, it is advantageous that the other reduction sensitization method is used only as an auxiliary of reduction sensitization and the ascorbic acid compound is used for main reduction sensitization. The another sensitization method combined with the method using the ascorbic acid compound can be selected from a method of adding another known reduction sensitizer to a silver halide emulsion, a method called silver ripening of precipitation or ripening in a low pAg environment at a pAg of 1 to 7, and a method of precipitation or Maturation in an alkaline environment at a pH of 8 to 11, which is called high pH maturation.

Of these further reduction sensitization methods combined with the method using the ascorbic acid compound, a method of adding another reduction sensitizer is generally preferred because the degree of reduction sensitization can be precisely controlled.

Other known reduction sensitizers include tin salts, amines and polyamines, hydrazine derivatives, formamidine sulfinic acid, silane compounds and borane compounds. However, the ascorbic acid compound can give better results than those obtained with the above known reduction sensitizers.

In the present invention, it is preferable that the reduction sensitization is carried out using the ascorbic acid compound in a process of preparing a silver halide emulsion. Also, the reduction sensitization is preferably carried out in the presence of at least one compound of compounds represented by the formulas (I), (II) and (III).

In the present invention, a monodisperse silver halide emulsion means an emulsion in which silver halide grains falling within the grain size range of -20 to +20% of the most common grain size constitute 60%, or more preferably 70% or more, and particularly preferably occupy 80% or more of the total weight of the silver halide grains.

Note that the most frequent grain size is defined as the grain size r¹ that maximizes the product of [n¹ x (r¹)³], where n¹ is the frequency of a grain with a grain size r¹. The -value (the number of significant figures is 3 and the least significant figure is rounded) is equal to a grain size that gives the maximum value of a volume frequency curve.

The grain size is a diameter in the case of a spherical silver halide grain and an equivalent spherical diameter in the case of a grain with a shape other than spherical.

A silver halide which can be used in combination with a light-sensitive material of the present invention may have any composition containing a component selected from the group consisting of silver bromide, silver iodobromide, silver iodochlorobromide, silver chlorobromide and silver chloride. A preferred silver halide is a silver iodobromide containing 30 mol% or less of silver iodide, silver bromide or silver chlorobromide.

A silver halide grain which can be used in the monodisperse silver halide emulsion of the present invention can be selected from regular crystals containing no twin crystal planes and grains containing twin crystal planes described in Japan Photographic Society (ed.), "Silver Salt Photographs, Basis of Photographic Industries" (Corona Co., p. 163), such as single twin crystals containing one twin crystal plane, parallel multiple twin crystals containing two or more parallel twin crystal planes, and non-parallel multiple twin crystals containing two or more non-parallel twin crystal planes, can be selected depending on its application. In the case of a regular crystal, a cubic grain having (100) faces, an octahedral grain having (111) faces, and a dodecahedral grain having (110) faces disclosed in JP-B-55-42737 and JP-A-60-222842 can be used. In addition, a grain having (h11), e.g. (211) faces, a grain having (hh1), e.g. (331) faces, a grain having (hk0), e.g. (210) faces, and a grain having (hk1), e.g. (321) faces, as reported in "Journal of Imaging Science", vol. 30, p. 247, 1986, can be used selectively depending on the application, although the manufacturing process needs to be improved. A grain including two or more facet types, e.g. a tetradecahedral grain containing both (100) and (111) faces, a grain containing both (100) and (110) faces, and a grain containing both (111) and (110) faces, can be used selectively depending on the application.

In the emulsion of the present invention, octahedral grains having a (111) face and tetradecahedral grains containing both a (100) face and a (111) face in one grain are particularly preferred.

The silver halide grains may be fine grains with a grain size of 0.1 µm or less or large grains with a projected surface diameter of 10 µm.

In the present invention, two or more types of monodisperse silver halide emulsions prepared in the presence of a thiosulfonic acid compound represented by formula (I), (II) or (III) and having different grain sizes with maximum frequency may be mixed in the same layer or coated independently in different layers. Moreover, two or more types of polydisperse silver halide emulsions or monodisperse emulsions other than those of the present invention may be mixed in an amount of half or less, and preferably 30% by weight or less, based on the total weight of the silver halide grains.

The photographic emulsions for use in the present invention can be prepared using methods described, for example, in P. Glafkides, "Chimie et Physique Photographique", Paul Montel, 1967; Duffin, "Photographic Emulsion Chemistry", Focal Press, 1966; and VL Zelikman et al, "Making and Coating the Photographic Emulsion", Focal Press, 1964. The method described is, for example, an acid method, a neutralization method and an ammonia method. Also, as a system for reacting a soluble silver salt and a soluble halide, a single mixing method, a double mixing method or a combination thereof can be used. Also, a so-called back mixing method for forming silver halide grains in the presence of a Excess silver ions can be used. As a system of the double mixing process, a so-called controlled double-jet process in which the pAg in the liquid phase in which the silver halide is produced is kept at a constant value can be used. According to this process, a silver halide emulsion with a regular crystal shape and almost uniform grain sizes is obtained.

In preparing a silver halide emulsion from regular grains, grains having a desired grain size can be obtained by carrying out nucleation and precipitation by a double-jet method while keeping the pAg constant and the degree of supersaturation so as not to cause new nucleation.

Furthermore, a method as described in JP-A-54-48521 can be used. In a preferred embodiment of this method, an aqueous potassium iodide bromide gelatin solution and an aqueous ammonium silver nitrate solution are preferably added to an aqueous gelatin solution containing silver halide grains while changing the addition rate as a function of time. In this embodiment, a highly monodisperse silver halide emulsion can be prepared by arbitrarily selecting, for example, the time function of the addition rate, pH, pAg and temperature. This method is described in detail in, for example, "Photographic Science and Engineering", vol. 6, pp. 159 to 165 (1962); "Journal of Photographic Science", vol. 12, pp. 242 to 261 (1964); US-PS 3,655,394 and GB-PS 1,413,748.

Tabular grains having an aspect ratio of 3 or more can also be used in the present invention. The tabular grains can be easily prepared by methods described, for example, in Cleve, "Photography Theory and Practice," p. 131 (1930); Gutoff, "Photographic Theory Science and Engineering," vol. 14, pp. 248 to 257 (1970); U.S. Patent Nos. 4,434,226, 4,414,310, 4,433,048, 4,439,520 and British Patent No. 2,112,157. When tabular grains are used, the covering power and color sensitization efficiency of a sensitizing dye are advantageously improved. These advantages are described in detail in U.S. Patent No. 4,434,226.

Tabular grains are preferred as the emulsion of the present invention. In particular, tabular grains in which grains with an aspect ratio of 3 to 8 occupy 50% or more of the total projected surface area are preferred.

Monodisperse tabular grains can be prepared, for example, by the following method. A fine-grained tabular silver iodobromide emulsion can be prepared by a double-jet process in which equimolar amounts of an aqueous silver nitrate solution and an aqueous mixture of a solution of potassium bromide and potassium iodide are added.

Then, equimolar amounts of an aqueous silver nitrate solution and an aqueous mixed solution of potassium bromide and potassium iodide are added while increasing the total addition amount and addition rate, thereby carrying out the precipitation several times or continuously. During the addition, the pAg is controlled so that the tabular shape is maintained and no new nucleation is caused. More specifically, the pAg is preferably 9 to 7.

The crystal structure may be uniform, may have different halogen compositions inside and on the surface, or may be a layered structure. These emulsion grains are disclosed, for example, in Japanese Patent Application No. 58-248469. In addition, silver halide layers each having a different composition may be epitaxially bonded to one another, or a compound other than a silver halide such as silver rhodanide or lead oxide may be bonded.

The silver halide emulsion of the present invention preferably has a distribution or structure of a halogen composition in its grains. A typical example is a core/shell type grain or a double structure grain having different halogen compositions in the interior and the surface layer of the grain, as disclosed in, for example, JP-B-43-13162, JP-A-61-215540, JP-A-60-222845 and JP-A-61-75337. In such a grain, the shape of the core part is sometimes identical and sometimes different from that of the entire grain with shell. Specifically, while the core part is cubic, the grain with shell is sometimes cubic or sometimes octahedral. On the other hand, while the core part is octahedral, the grain with shell is sometimes cubic or sometimes octahedral. Besides, while the core part is a clear regular grain, the grain with shell is sometimes slightly deformed or has sometimes no defined shape. In addition, not only a simple double structure but also a triple structure as disclosed in JP-A-60-222844, or a multilayer structure of multiple layers may be formed, or a thin film of a silver halide having a different composition may be formed on the surface of a core/shell double structure grain.

A structured grain can be obtained not only by providing the above surrounding structure on the core but also by forming a so-called junction structure. Examples of such a grain having a junction structure are disclosed in, for example, JP-A-59-133540, JP-A-58-108526, EP-A2-199 290, JP-B-58-24772 and JP-A-59-16254. A junction crystal having a different composition from that of the host crystal can be formed and bonded to a corner, an edge or a side of the host crystal. Such a junction crystal can be formed on the host crystal regardless of whether the host crystal has a homogeneous halogen composition or a core/shell structure.

The compound structure can of course be formed by a combination of silver halides. In addition, the compound structure can be formed by combining a silver salt compound that does not have a rock salt structure, such as silver rhodanate or silver carbonate, with a silver halide. A non-silver salt compound such as PbO can also be used as long as the compound structure can be formed with a silver halide.

In a silver iodobromide grain having the above structure, the silver iodide concentration may have any distribution. For example, in a core/shell type grain, the silver iodide content may be high in the core part and low in the shell part, or vice versa. Similarly, in a grain having a compound structure, the silver iodide content may be high in the host crystal and relatively low in a compound crystal, or vice versa.

In a grain with the above structure, the boundary between different halogen compositions may be clear or unclear due to the formation of solid solutions. Alternatively, a continuous structural change in the boundary region may be positively generated.

The silver halide emulsion for use in the present invention may be subjected to a treatment for rounding grains as disclosed in, for example, EP-B1-0 096 727 and EP-B1-0 064 412, or a treatment for modifying the surface of a grain as disclosed in DE-C2-2 306 447 and JP-A-60-221320.

The silver halide emulsion of the present invention is preferably used as a surface latent image type emulsion, but it can also be used as an internal latent image type emulsion by selecting a developer solution or developing conditions as disclosed in JP-A-59-133542. In addition, a surface internal latent image type emulsion covered with a thin shell can be effective depending on the application.

A solvent for the silver halide can be used effectively to accelerate ripening. On the other hand, in a known conventional method, an excess amount of halogen ions is supplied to the reaction vessel to accelerate ripening. It therefore seems that ripening can be promoted by adding only a halide solution to a reaction vessel. In addition, other ripening agents can be used. In this case, the total amount of these other ripening agents can be mixed in a dispersion medium in the reaction vessel before adding a silver salt and a halide thereto, or they can be added to the reaction vessel together with one or more halides, a silver salt or a deflocculant. Alternatively, the ripening agents can be added independently in the step of adding a halide and a silver salt.

Examples of ripening agents other than halogen ions are ammonium, amine compounds and thiocyanates, e.g. alkali metal thiocyanates (especially sodium thiocyanate or potassium thiocyanate) and ammonium thiocyanate.

In the present invention, it is very important to carry out chemical sensitization, typically sulfur or gold sensitization. Photographic properties of grains doped with 1 x 10⁻⁴ mol/mol Ag of polyvalent metal ions are significantly improved when chemical sensitization is carried out. A portion in which chemical sensitization is carried out varies depending on the composition, structure or shape of an emulsion grain. or the application of the emulsion. A chemically sensitized nucleus is embedded either in a portion deep inside the grain or in a portion near the surface of the grain or directly on the surface of the grain. Although the present invention is effective in either case, the chemically sensitized nucleus is particularly preferably formed in a portion near the surface. That is, the present invention is more effective on surface latent image type emulsions than on internal latent image type emulsions.

Chemical sensitization can be carried out using active gelatin as described in T.H. James, "The Theory of the Photographic Process", 4th ed., Macmillan, 1977, pp. 67-76. Alternatively, chemical sensitization can be carried out at a pAg of 5 to 10, a pH of 5 to 8 and a temperature of 30 to 80ºC using sulfur, selenium, tellurium, gold, platinum, palladium or iridium or a combination of several of these sensitizers as described in Research Disclosure Vol. 120, No. 12008 (April 1974), Research Disclosure Vol. 34, No. 13452 (June 1975), U.S. Patents 2,642,361, 3,297,446, 3,772,031, 3,857,711, 3 901,714, 4,266,018, 3,904,415 and GB-PS 1,315,755. Chemical sensitization is optimally carried out in the presence of a gold compound and a thiocyanate compound, a sulfur-containing compound described in US-PSs 3,857,711, 4,266,018 and 4,054,457 or a sulfur-containing compound such as a hypothiourea compound and a rhodanine compound. Chemical sensitization can also be carried out in the presence of a chemical sensitization aid.

Examples of chemical sensitization aids are compounds known to suppress fogging and increase sensitivity in the process of chemical sensitization, such as azaindene, azapyridazine and azapyrimidine. Examples of chemical sensitization aid modifiers are described in U.S. Patents 2,131,038, 3,411,914, 3,554,757, JP-A-58-126526 and G.F. Duffin, "Photographic Emulsion Chemistry", pp. 138 to 143.

The photographic emulsion according to the invention can contain various compounds to prevent the formation of fog during the manufacture, storage or photographic processing of the light-sensitive material or to stabilize the photographic properties. Examples of compounds known as antifoggants or stabilizers are azoles, e.g. benzothiazolium salts, nitroimidazoles, nitrobenzimidazoles, chlorobenzimidazoles, bromobenzimidazoles, mercaptothiazoles, mercaptobenzothiazoles, mercaptobenzimidazoles, mercaptothiadiazoles, aminotriazoles, benzotriazoles, nitrobenzotriazoles and mercaptotetrazoles (in particular 1-phenyl-5-mercaptotetrazole), mercaptopyrimidines, mercaptotriadines, thioketo compounds such as oxadrinthione; Azaindenes, e.g. triazaindene, tetraazaindenes (especially 4-hydroxy-substituted (1,3,3a,7)-tetraazaindenes) and pentaazaindenes. Examples are described in US Patents 3,954,474, 3,982,947 and JP-B-52-28660.

The photographic emulsion used in the present invention can be spectrally sensitized by, for example, methine dyes. Examples of dyes which can be used to used for this purpose are cyanine dyes, merocyanine dyes, composite cyanine dyes, composite merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes. The most effective dyes are those belonging to the class of cyanine dyes, merocyanine dyes and composite merocyanine dyes. In these dyes, nuclei normally used as basic heterocyclic nuclei in cyanine dyes may be included. Examples of such nuclei are pyrroline nuclei, oxazoline nuclei, thiazoline nuclei, pyrrole nuclei, oxazole nuclei, thiazole nuclei, selenazole nuclei, imidazole nuclei, tetrazole nuclei and pyridine nuclei; nuclei obtained by condensation of an alicyclic hydrocarbon ring to any of the above nuclei; and nuclei obtained by condensation of an aromatic hydrocarbon ring to any of the above nuclei, e.g., indolenine nuclei, benzindolenine nuclei, indole nuclei, benzoxazole nuclei, naphthoxazole nuclei, benzothiazole nuclei, naphthothiazole nuclei, benzoselenazole nuclei, benzimidazole nuclei and quinoline nuclei. These nuclei may have substituent groups on a carbon atom.

As a merocyanine dye or composite merocyanine dye, a 5- or 6-membered heterocyclic nucleus with ketomethylene structure, e.g. a pyrazolin-5-one nucleus, a thiohydantoin nucleus, a 2-thiooxazolidine-2,4-dione nucleus, a thiazolidine-2,4-dione nucleus, a rhodanine nucleus and a thiobarbituric acid nucleus can be contained.

These sensitizing dyes can be used individually or in combination of two or more. Combination of sensitizing dyes is often used to achieve supersensitization in particular. Typical examples of combinations are described in US Patents 2,688,545, 2,977,229, 3,397,060, 3,522,052, 3,527,641, 3,617,293, 3,628,964, 3,666,480, 3,672,898, 3,679,428, 3,703,377, 3,769,301, 3,814,609, 3,837,862, 4,026,707, GB Patents 1,344,281, 1,507,803, JP-B-43-4936, JP-B-53-12375, JP-A-52-110618, and JP-A-52-52-109925.

The emulsion may contain, in addition to the sensitizing dye, a dye which has no spectral sensitizing effect or a substance which does not substantially absorb visible light and has supersensitization.

The dye may be added to the emulsion at any time known to be conventionally effective for emulsion preparation. Usually, the dye is added after the completion of chemical sensitization and before coating. However, the dye may be added simultaneously with the chemical sensitizer so that spectral sensitization and chemical sensitization are carried out simultaneously, such as the dye may also be added before chemical sensitization as described in JP-A-58-113928, or added before the completion of silver halide precipitation to start spectral sensitization. In addition, as described in U.S. Patent No. 4,225,666, a portion of the above compound may be added before chemical sensitization and the remaining portion may be added afterward. In addition, as described in US Patent 4,183,756, the compound can be added at any time during silver halide grain formation.

The addition amount of the above dye may be 4 x 10⁻⁶ to 8 x 10⁻³ mol/mol of silver halide. When the silver halide grains have a preferable size of 0.2 to 1.2 µm, an addition amount of about 5 x 10⁻⁶ to 2 x 10⁻³ mol is more effective.

The above various additives are used in the light-sensitive material of the present invention. In addition to the above additives, however, various other additives may be used depending on the application. These additives are described in Research Disclosure No. 17643 (Dec. 1978) and No. 18716 (Nov. 1979) and are summarized in the following table. Additive Chemical sensitizers Sensitivity-increasing agents Spectral sensitizers, supersensitizers Brighteners Antifogging agents and stabilizers Light absorbers, filter dyes, ultraviolet absorbers Stain-preventing agents Color image stabilizers Hardeners Binders Plasticizers, lubricants Coating aids, surface-active agents Antistatic agents

In this invention, various color couplers can be used in the light-sensitive material. Specific examples of these couplers are described in the above-described Research Disclosure No. 17643, VII-C to G as patent references.

Preferred examples of a yellow coupler are, for example, described in US Patents 3,933,301, 4,022,620, 4,326,024, 4,401,752, JP-B-58-10739, and GB Patents 1,425,020 and 1,476,760.

Preferred examples of a magenta coupler are 5-pyrazolone and pyrazoloazole compounds. Particularly preferred examples of such compounds are, for example, described in U.S. Patent Nos. 4,310,619, 4,351,897, EP-73,636, U.S. Patent Nos. 3,061,432, 3,752,067, Research Disclosure No. 24220 (June 1984), JP-A-60-33552, Research Disclosure No. 24230 (June 1984), JP-A-60-43659, and U.S. Patent Nos. 4,500,630 and 4,540,654.

Examples of cyan couplers are phenol and naphthol couplers. Preferred examples of the coupler are described, for example, in US Pat. Nos. 4,052,212, 4,146,396, 4,228,233, 4,296,200, 2,369,929, 2,801,171, 2,772,162, 2,895,826, 3,772,002, 3,758,308, 4,334,011, 4,327,173, DE-OS 3,329,729, EP-A-121,365, US Pat. Nos. 3,446,622, 4,333,999, 4,451,559, 4,427,767 and EP-A-161,626.

Preferred examples of a color coupler for correcting additional undesirable absorption of the dye are those described in Research Disclosure No. 17643, VII-G, US Patent No. 4,163,670, JP-B-57-39413, US Patent Nos. 4,004,929, 4,138,258 and GB Patent No. 1,146,368.

Preferred examples of a coupler capable of forming a dye with suitable diffusibility are those described in US-PS 4,366,237, GB-PS 2,125,570, EP 96,570 and DE-OS 3,234,533.

Typical examples of a coupler which forms a polymerized dye are described in US Patent Nos. 3,451,820, 4,080,211, 4,367,282 and British Patent No. 2,102,173.

Couplers which release a photographically useful moiety upon coupling are also preferably used in the present invention. Preferred DIR couplers, i.e., couplers which release a development inhibitor, are described in the patents cited in Research Disclosure No. 17643, VII-F described above, as well as in JP-A-57-151944, JP-A-57-154234, JP-A-60-184243 and U.S. Patent 4,248,962.

Preferred examples of a coupler which imagewise releases a nucleating agent or a development accelerator upon development are those described in British Patents 2,097,140, 2,131,188 and JP-A-59-157638 and JP-A-59-170840.

Further examples of a coupler which can be used in the light-sensitive material of the present invention are competitive couplers described, for example, in U.S. Patent No. 4,130,427; polyequivalent couplers described, for example, in U.S. Patent Nos. 4,283,472, 4,338,393 and 4,310,618; DIR redox compounds, DIR couplers, DIR coupler-releasing couplers and DIR-releasing redox compounds described, for example, in JP-A-60-185950 and JP-A-62-24252; couplers which release a dye which assumes a colored form upon release and which are described in EP-A-173 302; bleaching accelerator-releasing couplers described, for example, in Research Disclosure Nos. 11449 and 24241 and JP-A-61-201247; and ligand-releasing couplers described, for example, in U.S. Patent No. 4,553,477.

Although examples of color couplers that can be used in the present invention are shown in Table B, the color couplers are not limited to these examples.

The couplers for use in this invention can be introduced into the light-sensitive material by various known dispersion methods. Examples of high boiling point solvents used in an oil-in-water dispersion method are described, for example, in U.S. Patent No. 2,322,027.

Examples of high boiling organic solvents used in the oil-in-water dispersion method and having a boiling point of 175ºC or more at normal pressure are phthalic acid esters, e.g. dibutyl phthalate, dicyclohexyl phthalate, di-2-ethylhexyl phthalate, decyl phthalate, bis(2,4-di-t-amylphenyl)phthalate, bis(2,4-di-t-amylphenyl)isophthalate and bis(1,1-diethylpropyl)phthalate; phosphoric acid or phosphonic acid esters, e.g. triphenyl phosphate, tricresyl phosphate, 2-ethylhexyldiphenyl phosphate, tricyclohexyl phosphate, tri-2-ethylhexyl phosphate, tridodecyl phosphate, tributoxyethyl phosphate, trichloropropyl phosphate, di-2-ethylhexylphenylphosphonate; Benzoic acid esters, e.g. 2-ethylhexyl benzoate, dodecyl benzoate and 2-ethylhexyl-p-hydroxybenzoate; amides, e.g. N,N-diethyldodecanamide, N,N-diethyllaurylamide and N-tetradecylpyrrolidone; alcohols or phenols, e.g. Isostearyl alcohol and 2,4-di-tert-amylphenol; aliphatic carboxylic acid esters, e.g., bis(2-ethylhexyl)sebacate, dioctyl azelate, glycerol tributylate, isostearyl lactate and trioctyl citrate; aniline derivatives, e.g., N,N-dibutyl-2-butoxy-5-tert-octylaniline; and hydrocarbons, e.g., paraffin, dodecylbenzene and diisopropylnaphthalene. An organic solvent having a boiling point of about 30°C or more, and preferably 50°C to about 160°C, can be used as the auxiliary solvent. Typical examples of the auxiliary solvent are ethyl acetate, butyl acetate, ethyl propionate, methyl ethyl ketone, cyclohexanone, 2-ethoxyethyl acetate and dimethylformamide.

Steps and effects of a latex dispersion process and examples of a loadable latex are described in US-PS 4,199,363, DE-OSen 2,541,274 and 2,541,230, etc.

Although the present invention can be applied to any photosensitive material, it is preferably applied to various color photosensitive materials. Typical examples of a color photosensitive material are a color negative film for general purposes or motion pictures, a color reversal film for slides or television, color papers, color positive films and color reversal papers.

When the light-sensitive material of the present invention is used as a material for color photography, the present invention can be applied to light-sensitive materials having various structures and light-sensitive materials having combinations of various layer structures and specific color materials.

Typical examples are: photosensitive materials in which the coupling speed and diffusibility of a color coupler are combined with a layer structure, as disclosed in, for example, JP-B-47-49031, JP-B-49-3843, JP-B-50-21248, JP-A-59-58147, JP-A-59-60437, JP-A-60-227256, JP-A-61-4043, JP-A-61-43743 and JP-A-61-42657; photosensitive materials in which a layer having the same color sensitivity is divided into two or more layers, as disclosed in JP-B-49-15495 and U.S. Patent No. 3,843,469; and photosensitive materials in which an arrangement of layers having high and low sensitivity and an arrangement of layers having different color sensitivities are defined, as disclosed in JP-B-53-37017, JP-B-53-37018, JP-A-51-49027, JP-A-52-143016, JP-A-53-97424, JP-A-53-97831, JP-A-62-200350 and JP-A-59-177551.

Examples of supports suitable for use in this invention are described in the above-mentioned Research Disclosures No. 17643, p. 28 and ibid. No. 18716, p. 647, right column to p. 648, left column.

The color photographic light-sensitive materials of the present invention can be processed for development by ordinary processes such as those described in the above-mentioned Research Disclosures No. 17643, pp. 28 to 29 and ibid., No. 18716, p. 651, left column to right column.

A color developer used in developing the light-sensitive material of the present invention is preferably an aqueous alkaline solution containing a color developing agent of the aromatic primary amine series as the main component. As the color developing agent, a compound of the aminophenol series is effective. In addition, a compound of the p-phenylenediamine series is preferably used. Typical examples of compounds of the p-phenylenediamine series are 3-methyl-4-amino-N,N-diethylaniline, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline, 3-methyl-4-amino-N-β-methanesulfonamidoethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methoxyethylaniline and their sulfates, hydrochlorides and p-toluenesulfonates. These compounds can be used in combination of two or more depending on the application.

In general, the color developing solution contains a pH buffering agent such as a carbonate, borate or phosphate of an alkali metal, and a development retarder or an anti-fogging agent such as a bromide, an iodide, a benzimidazole, a benzothiazole or a mercapto compound. If necessary, the color developing solution may also contain a preservative such as hydroxylamine, diethylhydroxylamine, a hydrazine sulfite, a phenylsemicarbazide, triethanolamine, a catecholsulfonic acid or triethylenediamine(1,4-diazabicyclo[2,2,2]octane); an organic solvent such as ethylene glycol or diethylene glycol; a development accelerator such as benzyl alcohol, polyethylene glycol, a quaternary ammonium salt or an amine; a dye-forming coupler; a competing coupler; a fogging agent such as sodium borohydride; an auxiliary developing agent such as 1-phenyl-3-pyrazolidone; a viscosity increasing agent and a chelating agent such as an aminopolycarboxylic acid, an aminopolyphosphonic acid, an alkylphosphonic acid or a phosphonocarboxylic acid. Examples of chelating agents are ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethyltriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, hydroxyethyliminodiacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, nitrilo-N,N,N-trimethylenephosphonic acid, ethylenediamine-N,N,N',N'tetramethylenephosphonic acid and ethylenediamine-di(o-hydroxyphenylacetic acid) and their salts.

To perform reversal development, generally, black-and-white development is carried out and then color development is carried out. For a black-and-white developing solution, well-known black-and-white developing agents, e.g., dihydroxybenzenes such as hydroquinone, 3-pyrazolidones such as 1-phenyl-3-pyrazolidone, and aminophenols such as N-methyl-p-aminophenol, may be used singly or in combination of two or more.

The pH of the color developing solution and the black and white developing solution is generally 9 to 12. Although the replenishment amount of the developing solution depends on the color photographic light-sensitive material being processed for development, it is generally 3 liters or less per m² of light-sensitive material. The replenishment amount can be reduced to 500 ml or less by lowering the bromide ion concentration in the replenisher. In the case of reducing the replenishment amount, the contact area of the developing solution in a process tank is air-conditioned. preferably reduced to prevent evaporation and oxidation of the solution. The replenishing amount can also be reduced by using an agent capable of suppressing accumulation of bromide ions in the developing solution.

The color development time is usually set between 2 to 5 minutes. However, the processing time can be shortened by setting a high temperature and a high pH in the developer solution and by using the color developing agent in high concentration.

The photographic emulsion layer is generally subjected to bleaching after color development. Bleaching can be carried out either simultaneously with fixing (bleach-fixing) or independently. In addition, bleach-fixing can be carried out after bleaching to increase the processing speed. Also, processing can be carried out in a bleach-fixing bath with two continuous tanks, wherein fixing can be carried out before bleach-fixing or bleaching can be carried out after bleach-fixing, depending on the application. Examples of bleaching agents are compounds of a polyvalent metal such as iron(III), cobalt(III), chromium(VI) and copper(II); a peroxide, a quinone and a nitro compound. Typical examples of bleaching agents are ferricyanides; dichromates; organic complex salts of iron(III) or cobalt(III), e.g. a complex salt of iron(III) or cobalt(II) with an aminopolycarboxylic acid, such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, methyliminodiacetic acid, 1,3-diaminopropanetetraacetic acid and glycol ether diaminetetraacetic acid, or a complex salt with citric acid, tartaric acid or malic acid; a persulfate, a bromate, a permanganate and a nitrobenzene. Among these compounds, a ferric complex salt with an aminopolycarboxylic acid such as a ferric complex salt with ethylenediaminetetraacetic acid and a persulfate are preferred because they can increase the processing speed and prevent environmental pollution. In particular, the ferric complex salt with an aminopolycarboxylic acid is effective in both the bleaching solution and the bleach-fixing solution. The pH of the bleaching solution or the bleach-fixing solution when the ferric complex salt with an aminopolycarboxylic acid is used is normally 5.5 to 8. However, in order to increase the processing speed, the processing may be carried out at a lower pH.

A bleach accelerator may be used in the bleach solution, the bleach-fix solution and their pre-baths if necessary. Examples of effective bleaching accelerators are described in the following patents: Compounds having a mercapto group or disulfide group are described, for example, in U.S. Patent No. 3,893,858, German Patent Nos. 1,290,812, 2,059,988, JP-A-53-32736, JP-A-53-57831, JP-A-53-37418, JP-A-53-72623, JP-A-53-95630, JP-A-53-95631, JP-A-53-104232, JP-A-43-124424, JP-A-141623, JP-A-53-28426 and Research Disclosure No. 17129 (July 1978); Thiazolidine derivatives are described in JP-A-50-140129; thiourea derivatives are described in JP-B-45-8506, JP-A-52-20832, JP-A-53-32735 and US-PS 3 706 561; iodides are described in DE-PS 1,127,715 and JP-A-58-16235; polyoxyethylene compounds are described in German Patents 966,410 and 2,748,430; polyamine compounds are described in JP-B-45-8836; other compounds are described in JP-A-49-42434, JP-A-49-59644, JP-A-53-94927, JP-A-54-35737, JP-A-55-26506 and JP-A-58-163940; and bromide ions are also usable. Of the above compounds, a compound having a mercapto or disulfide group is preferred because it has a good accelerating effect. In particular, the compounds described in US-PS 3,893,858, German-PS 1,290,812 and JP-A-53-95630 are preferred. The compound of US-PS 4,552,834 is also preferred. These bleaching accelerators can be added to the light-sensitive material. They are particularly effective in bleach-fixing a color light-sensitive material for photography.

Examples of fixing agents are thiosulfates, thiocyanates, thioether compounds, thiourea and a large amount of iodide. Of these compounds, thiosulfates, especially ammonium thiosulfate, can be used in the widest range of applications. As a preservative of the bleach-fix solution, a sulfite, a bisulfite or carbonyl bisulfite adduct is preferred.

The silver halide color photographic light-sensitive material of the present invention is normally subjected to water washing and/or stabilization steps after desilvering. The amount of water used in the washing step can be arbitrarily selected in a wide range depending on the properties of the light-sensitive material (e.g., the properties required for by the substances used, such as a coupler), the application of the material, the temperature of the water, the number of water tanks (the number of stages), the supplementary scheme, e.g. cocurrent or countercurrent, and other conditions. The relationship between the amount of water and the number of water tanks in a multi-stage countercurrent scheme can be obtained by a method described in "Journal of the Society of Motion Picture and Television Engineers", Vol. 64, pp. 248 to 253 (May 1955).

According to the multi-stage countercurrent scheme described above, the amount of water used for washing can be greatly reduced. However, since the washing water remains in the tanks for a long time, bacteria proliferate and floating substances produced by the bacteria may undesirably adhere to the photosensitive material. To solve this problem in processing the color photographic photosensitive material of the present invention, a method of reducing the calcium and magnesium ion concentration as described in Japanese Patent Application No. 61-131632 can be used very effectively. In addition, a germicide such as an isothiazolone compound and thiabendazole described in JP-A-57-8542, a chlorine series germicide such as chlorinated sodium isocyanurate, and germicides such as benzotriazole described in Hiroshi Horiguchi, "Chemistry of Antibacterial and Antifungal Agents", Eiseigijutsu-Kai, editor, "Sterilization, Antibacterial and Antifungal Techniques for Microorganisms", and Nippon Bokin Bokabi Gakkai, editor, "Cyclopedia of Antibacterial and Antifungal Agents".

The pH of the water for washing the photographic light-sensitive material of the present invention is 4 to 9, and preferably 5 to 8. The water temperature and the washing time may vary depending on the properties and applications of the light-sensitive material. Normally, the washing time is 20 seconds to 10 minutes at a temperature of 15 to 45°C, and preferably 30 seconds to 5 minutes at 25 to 40°C. The light-sensitive material of the present invention can be processed directly by a stabilizing solution instead of washing. Any of the known methods described in JP-A-57-8543, JP-A-58-14834 and JP-A-60-220345 can be used in such stabilization processing.

In addition, stabilization is sometimes carried out after washing. An example of this is the case where a stabilizing bath containing formalin and a surfactant is used as the final bath of the color photosensitive material for photography. Various chelating agents and anti-mold agents can also be added to the stabilizing bath.

The overflow liquid generated when refilling the washing and/or stabilizing solution can be reused in another step, such as a desilvering step.

The silver halide color light-sensitive material of the present invention may contain a color developing agent to simplify processing for development and increase processing speed. In the case of adding a color developing agent to the color light-sensitive material, various precursors of the color developing agent are preferably used. Examples of precursors are indoaniline series compounds described in U.S. Patent No. 3,342,597; Schiff base compounds described in U.S. Patent No. 3,342,599 and Research Disclosure Nos. 14850 and 15159; aldol compounds described in Research Disclosure No. 13924; metal complex salts described in U.S. Patent No. 3,719,492; and urethane series compounds described in JP-A-53-135628.

The silver halide color light-sensitive material of the present invention may contain various 1-phenyl-3-pyrazolidones to optionally accelerate color development. Typical examples of such compounds are described in JP-A-56-64339, JP-A-57-144547 and JP-A-58-115438.

Each processing solution is used in the present invention at a temperature of 10 to 50°C. Although the normal solution temperature is 33 to 38°C, processing can be accelerated at higher temperatures to shorten the processing time, or the image quality and/or stability of a processing solution can be improved at a lower temperature. In order to save silver for the photosensitive material, processing using cobalt intensification or hydrogen peroxide intensification as described in German Patent No. 2,226,770 or U.S. Patent No. 3,674,499 can be carried out.

The silver halide light-sensitive material of the present invention can also be used for heat-developable light-sensitive materials described, for example, in US Pat. No. 4,500,626, JP-A-60-133449, JP-A-59-218443, JP-A-61-238056 and EP-A2-210 660.

The present invention is described in more detail below by its examples.

EXAMPLE 1 (comparative example)

60 g of gelatin and 900 ml of water were added to a stainless steel reactor with a volume of 4 L, and an equal volume of an aqueous silver nitrate solution and an aqueous mixed solution of potassium bromide and potassium iodide were added to the vessel kept at 60 °C to prepare a silver iodobromide emulsion serving as a core. Then, equal volumes of an aqueous silver nitrate solution and an aqueous potassium bromide solution were added to cover the core with silver bromide to prepare a core/shell type silver iodobromide emulsion.

The addition times and concentrations of the addition solutions are listed in Table 1-1. During the addition, the pAg was maintained at 8.6 for the first 10 minutes, at 8.3 for the next 80 minutes, and at 7.3 for the last 20 minutes.

After grain formation, the emulsion was subjected to a normal desalting/washing process and then redispersed at a temperature of 40ºC, a pAg of 8.9 and a pH of 6.3 to prepare an emulsion Em-101. The prepared emulsion comprises octahedral grains with a (III) face having a maximum grain size of 0.6 µm and an average AgI content (formulation value) of 5 mol%. In the emulsion, the weight of a silver halide falling within the grain size range of -20 to +20% of the most common grain size was 75% of the total weight of the silver halide grains. TABLE 1-1 Aqueous silver nitrate solution Aqueous potassium halide solution Time (min) Quantity Stirring speed (rpm)

When grain formation was carried out by the same method as for Em-101, thiosulfonic acid compounds 1-6, 1-2, 1-16 and 1-21 were added 1 minute before shell formation was started, and optimum amounts of the following reduction sensitizers 2-A, 2-B and 2-C were added 1 minute after the start of shell formation, thus preparing inventive emulsions Em-102 to Em-113 listed in Table 1-2 below. TABLE 1-2 Thiosulfonic Acid Reduction Sensitizer Emulsion No. Compound Addition Amount (per mole Ag) Reduction Sensitizers: 2-A Thiourea Dioxide 2-B Dimethylaminoborane 2-C Stannous Chloride

Em-114 was prepared using the same procedure as Em-101, except that the stirring speed was reduced to 500 rpm after 50 minutes in Table 1-1. The prepared emulsion comprised grains with a maximum grain size of 0.6 µm and had an average AgI content (formulation value) of 5 mol%. In the emulsion, the weight of silver halide falling within the grain size range of -20 to +20% of the most common grain size was 65% of the total weight of the silver halide grains.

When grain formation was carried out according to the same steps as for Em-114, optimum amounts of the thiosulfonic acid compounds and reduction sensitizers were added according to the same steps as for the emulsions Em-105 to Em-107 and Em-111 to Em-113, thereby preparing the inventive emulsions Em-115 to Em-120 listed in Table 1-3. TABLE 1-3 Thiosulfonic Acid Reduction Sensitizer Emulsion No. Compound Addition Amount (per mole Ag)

Emulsions as comparative examples were prepared as follows. Em-121 was prepared following the same steps as Em-101, except that aqueous solutions of silver nitrate and potassium halide were added during nucleation so that the addition amounts per unit time were kept constant and the maximum grain size was set equal to that of Em-101. The prepared emulsion had a maximum grain size of 0.6 µm and an average AgI content (formulation value) of 5 mol%. In the emulsion, the weight of a silver halide falling within the grain size range of -20 to +20% of the most common grain size was 55% of the total weight of the silver halide grains.

When grain formation was carried out according to the same steps as for Em-121, optimum amounts of the thiosulfonic acid compounds and reduction sensitizers were added according to the same steps as for Em-102 to Em-113, to prepare emulsions Em-121 to Em-133 listed in Table 1-4 as comparative examples. TABLE 1-4 Thiosulfonic Acid Reduction Sensitizer Emulsion No. Compound Addition Amount (per mole Ag)

The emulsions Em-102 to Em-113 according to the invention and the emulsions Em-101, Em-114 and Em-121 to Em-133, which were prepared as described above, were optimally subjected to gold plus sulfur sensitization using sodium thiosulfate and chloroauric acid to prepare emulsions.

Emulsions and protective layers in the amounts listed in Tables 1-5 were coated on triacetyl cellulose film supports with primer layers. TABLE 1-5 Emulsion layer Emulsion (chemically sensitized emulsions up to) (Silver mol/m²) Coupler (mol/m²) Tricresyl phosphate (g/m²) Gelatin (g/m²) Protective layer 2,4-dichlorotriazine-6-hydroxy-s-triazine sodium salt (g/m²) Gelatin (g/m²)

These samples were subjected to sensitometric exposure and then the following color development was carried out.

The processed samples were subjected to density measurement using a green filter. The obtained Photographic performance results are listed in Table 1-6.

Development was carried out under the following conditions at a temperature of 38ºC.

1. Color development 2 min. 45 sec.

2. Bleaching 6 min. 30 sec.

3. Wash 3 min. 15 sec.

4. Fixation 6 min. 30 sec.

5. Wash 3 min. 15 sec.

6. Stabilization 3 min. 15 sec.

The compositions of the processing solutions used in the above steps were as follows:

Color developer solution:

Sodium nitriloacetic acid 1.4 g

Sodium sulphite 4.0 g

Sodium carbonate 30.0 g

Potassium bromide 1.4 g

Hydroxylamine sulfate 2.4 g

4-(N-ethyl-N-β-hydroxyethylamino)-2-methylaniline sulfate 4.5 g

Water to 1 l

Bleaching solution:

Ammonium bromide 160.0 g

Ammonia water (28% w/w) 25.0 ml

Iron(III) sodium ethylenediaminetetraacetate trihydrate 130 g

Glacial acetic acid 14 ml

Water to 1 l

Fixing solution:

Sodium tetrapolyphosphate 2.0 g

Sodium sulphite 4.0 g

Ammonium thiosulfate (700 g/l) 175.0 ml

Sodium bisulfite 4.6 g

Water to 1 l

Stabilizing solution:

Formalin 8.0 ml

Water to 1 l

In this case, a normal wedge exposure was performed both for 1 second and for 1/100 second.

A light source was set to a color temperature of 4800⁰K using a filter, and blue light was extracted using a blue filter (BPN42, available from Fuji Photo Film Co., Ltd.). The sensitivities were compared using a density at a point of one veil through an optical density of 0.2. The sensitivities are listed as relative sensitivities, assuming that the sensitivity of a sample using the emulsion Em-101 is 100 (100 for both 1/100" and 1"). In addition, the maximum density Dmax is shown as a relative density, assuming that the Dmax of the sample using Em-101 is 100.

As shown in Tables 1-6, the emulsions according to the invention show low fog, high sensitivity and a high Dmax. TABLE 1-6 Emulsion No. Second Exposure Sensitivity Fog Maximum density (Dmax)

EXAMPLE 2

The emulsion Em-201, which is completely identical to Em-101, was prepared using the same procedure as in Example 1.

When grain formation was carried out by the same method as Em-201, a reduction sensitizer A-1 (L-ascorbic acid) and stannous chloride were added in the amounts listed in Table 2-1 1 minute after the start of shell formation to prepare emulsions Em-202 and Em-203. TABLE 2-1 Emulsion Reduction sensitizer Addition amount per mole Ag L-ascorbic acid Stannous chloride (II)

When grain formation was carried out by the same method as for Em-201, thiosulfonic acids 1-2, 1-6 and 1-16 were added 1 minute before the start of shell formation and optimum amounts of reduction sensitizers L-ascorbic acid and stannous chloride were added 1 minute after the start of shell formation, thus preparing emulsions Em-204 to Em-209 of the present invention and comparative examples. TABLE 2-2 Emulsion Reduction Stabilizer Thiosulfonic Acid Compound Compound Addition Amount (per mole Ag) L-Ascorbic Acid Stannous Chloride

Em-210 was prepared by the same procedures as Em-201 except that the stirring speed was reduced to 500 rpm after 50 minutes in Table 1-1. The prepared emulsion had a most common grain size of 0.6 µm and an average AgI content (formulation value) of 5 mol%. In the emulsion, the weight of a silver halide falling within the grain size range of -20 to +20% of the most common grain size was 65% of the total weight of the silver halide grains.

When grain formation was carried out using the same method as for Em-210, optimum amounts of thiosulfonic acid compounds and reduction sensitizers were added according to the same methods as for Em-202 to Em-209 to prepare the inventive emulsions Em-211 to Em-216 listed in Table 2-3. TABLE 3-3 Emulsion Reduction Stabilizer Thiosulfonic Acid Compound Compound Addition Amount (per mole Ag) L-Ascorbic Acid Stannous Chloride

Emulsions as comparative examples were prepared as follows. Em-217 was prepared using the same procedures as Em-201, except that during nucleation, aqueous solutions of silver nitrate and potassium halide were added so that their addition amounts per unit time were kept constant and the most common grain size was set equal to that of Em-201. The prepared emulsion had a most common grain size of 0.6 µm and an average AgI content (formulation value) of 5 mol%. In the emulsion, the weight of a silver halide falling within the grain size range of -20 to +20% of the most common grain size was 55% of the total weight of the silver halide grains.

When grain formation was carried out according to the same procedures as for Em-217, optimum amounts of the thiosulfonic acid compounds and reduction sensitizers were added according to the same procedures as for Em-202 to Em-209, thereby preparing the inventive emulsions Em-218 to Em-223 listed in Table 2-4. TABLE 2-4 Emulsion Reduction Stabilizer Thiosulfonic Acid Compound Compound Addition Amount (per mole Ag) L-Ascorbic Acid Stannous Chloride

The emulsions Em-201 to Em-223 according to the invention and the comparative examples were optimally subjected to gold-plus-sulfur sensitization using sodium thiosulfate and chloroauric acid to prepare emulsions.

Samples 201 to 223 of this example were prepared by the same procedures as in Example 1, except that emulsion Em-201 to Em-223 were used instead of emulsion Em-101. Sensitometry was then carried out by the same procedures as in Example 1, except that the exposure time was changed from 1 second and 1/100 second to 10 seconds and 1/100 second.

The results obtained are summarized in Table 2-5. TABLE 2-5 Sample Second Sensitivity Veil Maximum Density Remarks Invention

As can be seen from Table 2-5, the emulsions according to the invention show low fog, high sensitivity (especially in the case of low intensity) and a high Dmax.

Samples 201 to 223 coated with emulsions Em-261 to Em-223 were stored at a temperature of 25ºC and a humidity of 60% for 12 months and a sensitometric test was carried out in a similar manner.

Table 2-6 shows the results represented by the relative sensitivities, assuming that the sensitivity of the sample obtained before storage is 201 100. TABLE 2-6 Sample Second Sensitivity Veil Remarks Invention

As can be seen from Table 2-6, the decrease in sensitivity and increase in fog of all samples coated with the emulsions according to the invention are small after storage. This means that each sample had good storage stability.

When the experiment was carried out according to the same procedures as above for ascorbic acid compounds A-2 to A-10, the same effects were obtained.

EXAMPLE 3 (comparative example)

A plurality of layers having the following compositions were coated on a primed triacetylcellulose film support to prepare a multilayer color photosensitive material 301.

Light-sensitive layer composition:

Numbers corresponding to the respective components indicate the coating amounts in the units of g/m². The coating amounts of a silver halide and colloidal silver are represented by the amount of silver. The coating amount of a sensitizing dye is indicated in the units of moles per mole of silver halide in the same layer.

Layer 1: Antihalation Layer

Black colloidal silver 0.2

Gelatin 2.6

Cpd-3 0.2

Solv-1 0.02

Layer 2: Intermediate layer

Fine-grained silver bromide (average grain size: 0.07 µm) 0.15

Gelatin 1.0

Layer 3: low-sensitivity red-sensitive emulsion layer

Monodisperse silver iodobromide emulsion (silver iodide = 5.5 mol.%, most common grain size = 0.3 µm, coefficient of variation of grain size (hereinafter simply referred to as coefficient of variation) = 19%) 1.5

Gelatin 3.0

ExS-1 2.0 x 10⊃min;⊃4;

ExS-2 1.0 x 10⊃min;⊃4;

ExS-3 0.3 x 10⊃min;⊃4;

ExC-1 0.7

ExC-2 0.1

ExC-3 0.02

Cpd-1 0.01

Solv-1 0.8

Solv-2 0.2

Solv-4 0.1

Layer 4: highly sensitive red-sensitive emulsion layer

Monodisperse silver iodobromide emulsion I 1.2

Gelatin 2.5

ExS-1 3.0 x 10-4

ExS-2 1.5 x 10⊃min;⊃4;

ExS-3 0.45x 10⊃min;⊃4;

ExC-4 0.15

ExC-5 0.05

ExC-2 0.03

ExC-3 0.01

Solv-1 0.05

Solv-2 0.3

Layer 5: Intermediate layer

Gelatin 0.8

Cpd-2 0.05

Solv-3 0.01

Layer 6: low-sensitivity green-sensitive emulsion layer

Monodisperse silver iodobromide emulsion (silver iodide = 5 mol.%, most common grain size = 0.3 µm, coefficient of variation = 19 %) 0.4

Monodisperse silver iodobromide emulsion (silver iodide = 7 mol.%, most common grain size = 0.5 µm, coefficient of variation = 20 %) 0.8

Gelatin 3.0

ExS-4 1 x 10⊃min;⊃4;

ExS-5 4 x 10⊃min;⊃4;

ExS-6 1 x 10⊃min;⊃4;

ExM-6 0.2

ExM-7 0.4

ExM-8 0.16

ExC-9 0.05

Solv-2 1.2

Solv-4 0.05

Solv-5 0.01

Layer 7: highly sensitive green-sensitive emulsion layer

Monodisperse silver iodobromide emulsion II 0.9

Gelatin 1.6

ExS-4 0.7 x 10⊃min;⊃4;

ExS-5 2.8 x 10-4

ExS-6 0.7 x 10⊃min;⊃4;

ExM-7 0.05

ExM-8 0.04

ExC-9 0.01

Solv-1 0.08

Solv-2 0.3

Solv-4 0.03

Layer 8: Yellow filter layer

Yellow colloidal silver 0.2

Gelatin 0.9

Cpd-2 0.2

Solv-2 0.1

Layer 9: low-sensitivity blue-sensitive emulsion layer

Monodisperse silver iodobromide emulsion (silver iodide = 6 mol.%, most common grain size = 0.3 µm, coefficient of variation = 20 %) 0.4

Monodisperse silver iodobromide emulsion (silver iodide = 5 mol%, most common grain size = 0.6 µm, coefficient of variation = 17%) 0.4

Gelatin 2.9

ExS-7 1 x 10⊃min;⊃4;

ExS-8 1 x 10⊃min;⊃4;

ExY-10 1.2

ExC-3 0.05

Solv-2 0.4

Solv-4 0.1

Layer 10: highly sensitive blue-sensitive emulsion layer

Monodisperse silver iodobromide emulsion III 0.5

Gelatin 2.2

ExS-7 5 x 10⊃min;⊃5;

ExS-8 5 x 10⊃min;⊃5;

ExY-10 0.4

ExC-3 0.02

Solv-2 0.1

Layer 11: First protective layer

Gelatin 1.0

Cpd-3 0.1

Cpd-4 0.1

Cpd-5 0.1

Cpd-6 0.1

Solv-1 0.1

Solv-4 0.1

Layer 12: Second protective layer

Fine-grained silver bromide emulsion (average grain size = 0.07 µm) 0.25

Gelatin 1.0

Polymethyl methacrylate grains (diameter = 1.5 µm) 0.2

Cpd-8 0.5

In addition to the above components, a surfactant Cpd-7 and a hardener H-1 were added. The formulas of the compounds used are listed in Table C.

The iodide content and the silver amount of the shell part of Em-101 during core-grain formation were arbitrarily to prepare monodisperse silver iodobromide emulsion I (silver iodide = 3.5 mol.%, most common grain size = 0.7 µm) of layer 4, monodisperse silver iodobromide emulsion II (silver iodide = 3.5 mol.%, most common grain size = 0.8 µm) of layer 7, and monodisperse silver iodobromide emulsion III (silver iodide = 6 mol.%, most common grain size = 1.2 µm) of layer 10, thereby producing sample 301. The percentage of grains falling within the grain size range of -20 to +20% of the most common grain size was 73% in emulsion I, 70% in emulsion II, and 66% in emulsion III. Emulsions I to III were optimally subjected to gold plus sulfur sensitization using sodium thiosulfate and chloroauric acid.

Samples 302 to 305 were prepared by the same procedures as Sample 301, except that the above emulsions were replaced by emulsions prepared by adding thiosulfonic acid compounds and reduction sensitizers as shown in Table 3-1(A) during grain formation as in the case of Em-102 to Em-213.

These samples were subjected to sensitometric exposure and then to subsequent color development.

The processed samples were subjected to density measurement using red, green and blue filters. The results obtained are shown in Table 3-1.

The results of the photographic properties are expressed in terms of relative sensitivities of the red, green and blue sensitive layers, assuming that the sensitivities of Sample 301 are each 100.

Processing method:

The color development process was carried out at 38ºC with the following processing steps.

Color development 3 min 15 sec

Bleaching 6 min 30 sec

Laundry 2 min 10 sec

Fixation 4 min 20 sec

Laundry 3 min 15 sec

Stabilization 1 min 5 sec

The compositions of the processing solutions used in the respective steps were as follows:

Color developer solution:

Diethylenetriaminepentaacetic acid 1.0 g

1-Hydroxyethylidene-1,1-diphosphonic acid 2.0 g

Sodium sulphite 4.0 g

Potassium carbonate 30.0 g

Potassium bromide 1.4 g

Potassium iodide 1.3 mg

Hydroxylamine sulfate 2.4 g

4-(N-ethyl-N-β-hydroxyethylamino)-2- methylaniline sulfate 4.5 g

Water to 1.0 l

pH10.0

Bleaching solution:

Iron ammonium ethylenediaminetetraacetate 100.0 g

Disodium ethylenediaminetetraacetate 10.0 g

Ammonium bromide 150.0 g

Ammonium nitrate 10.0 g

Water to 1.0 l

pH6.0

Fixing solution:

Disodium ethylenediaminetetraacetate 1.0 g

Sodium sulphite 4.0 g

Ammonium thiosulfate, aqueous solution (70%) 175.0 ml

Sodium bisulfite 4.6 g

Water to 1.0 l

pH6.6

Stabilization solution:

Formalin (40%) 2.0 ml

Polyoxyethylene p-monononylphenyl ether (average degree of polymerization = 10) 0.3 g

Water to 1.0 l TABLE 3-1(A) Layer Monodisperse Silver Iodobromide Emulsion I Thiosulfonic Acid Reduction Sensitizer Sample No. Compound Addition Amount (per mole Ag) Invention Layer Monodisperse Silver Iodobromide Emulsion II Thiosulfonic Acid Reduction Sensitizer Sample No. Compound Addition amount (per mole Ag) Invention Layer Monodisperse silver iodobromide emulsion III Thiosulfonic acid Reduction sensitizer Sample No. Compound Addition amount (per mole Ag) Invention TABLE 3-1(B) Sample No. Red-sensitive layer Green-sensitive layer Blue-sensitive layer Fog Sensitivity Invention

As can be seen from Table 3-1, the emulsions according to the invention show an effect of increased sensitivity with almost no increase in fog.

EXAMPLE 4

Samples 401 to 404 were prepared by the same procedures as Sample 301 in Example 3. Note that in Samples 402 to 404, emulsions Em-204 to Em-206 were used so that monodisperse silver iodobromide emulsions I to III were prepared for use in Layers 4, 7, and 10, respectively, and thiosulfonic acid compounds and a reduction sensitizer, L-ascorbic acid, were added to the emulsions as shown in Table 4-1(A). Samples 402 to 404 are otherwise the same as Sample 401.

Samples 401 to 404 were subjected to sensitometric exposure using the same procedures as in Example 3. Subsequently, color development and then measurement were carried out using the same procedures as in Example 3.

The results are summarized in Table 4-1(B). TABLE 4-1(A) Layer Monodisperse Silver Iodobromide Emulsion I Thiosulfonic Acid Compound L-Ascorbic Acid Sample No. Compound Addition Amount (per mole Ag) Invention Layer Monodisperse silver iodobromide emulsion II Thiosulfonic acid compound L-ascorbic acid Sample No. Compound Addition amount (per mole Ag) Invention Layer Monodisperse silver iodobromide emulsion III Thiosulfonic acid compound L-ascorbic acid Sample No. Compound Addition amount (per mole Ag) Invention TABLE 4-1(B) Sample No. Red-sensitive layer Green-sensitive layer Blue-sensitive layer Sample No. Veil Sensitivity Invention

As can be seen from Table 4-1, the emulsions according to the invention show an effect of increasing the sensitivity with almost no increase in the fog.

When the photographic properties after storage were checked using the same procedures as in Example 2, each sample using the emulsion of the present invention had good storage stability.

EXAMPLE 5 (comparative example)

Samples 301 to 305 were exposed by the same procedures as in Example 3 and processed as follows using an automatic developing machine. Processing method: Step Time Temperature Colour development Bleaching Bleach-fixing Laundry Stabilisation Drying

The compositions of the process solutions are given below.

Color developer solution: (g)

Diethylenetriaminepentaacetic acid 1.0

1-Hydroxyethylidene-1,1-diphosphonic acid 3.0

Sodium sulphite 4.0

Potassium carbonate 30.0

Potassium bromide 1.4

Potassium iodide 1.5 mg

Hydroxylamine sulfate 2,4

4-[N-Ethyl-N-(β-hydroxyethyl)amino]-2- methylaniline sulfate 4.5

Water to 1.0 l

pH10.05

Bleaching solution: (g)

Iron ammonium ethylenediaminetetraacetate (dihydrate) 120.0

Disodium ethylenediaminetetraacetate 10.0

Ammonium bromide 100.0

Ammonium nitrate 10.0

Bleaching accelerator 0.005 mol

aqueous ammonia solution (27%) 15.0 ml

Water to 1.0 l

pH6.3

Bleach-fixing solution: (g)

Iron ammonium ethylenediaminetetraacetate (dihydrate) 50.0

Disodium ethylenediaminetetraacetate 5.0

Sodium sulphite 12.0

aqueous ammonium thiosulfate solution (70%) 240.0 ml

aqueous ammonia solution (27%) 6.0 ml

Water to 1.0 l

pH7.2

Washing solution:

Tap water was passed through a mixed bed column filled with a strong acidic H+ type cation exchange resin (Amberlite IR-120B, available from Rohm & Haas Co.) and a strong basic OH+ type anion exchange resin (Amberlite IR-400) to adjust the calcium and magnesium concentrations to 3 mg/L or less. Then, 20 mg/L of sodium isocyanuric dichloride and 1.5 g/L of sodium sulfate were added. The pH of the solution fell within the range of 6.5 to 7.5.

Stabilizing solution (g)

Formalin (37%) 2.0 ml

Polyoxyethylene p-monononylphenyl ether (average degree of polymerization = 10) 0.3

Disodium ethylenediaminetetraacetate 0.05

Water to 1.0 l

pH 5.0 to 8.0

Inventive samples 302 to 305 gave the same good results as in Example 3 after being subjected to the above processing.

EXAMPLE 6

Sample 401 of Comparative Example and Samples 402 to 404 of the present invention obtained in Example 4 were exposed by the same procedures as in Example 4 and then processed in an automatic developing machine.

The processing method and the compositions of the processing solutions were the same as in Example 5. Inventive samples 402 to 404 provided the good results of Example 4 after being subjected to the above processing.

EXAMPLE 7 (comparative example)

Samples 301 to 305 of Example 3 were exposed using the same method as in Example 3 and processed as follows using an automatic developing machine. Processing method: Step Time Temperature Colour development Bleach-fixation Laundry Stabilisation Drying

The compositions of the process solutions are given below.

Color developer solution: (g)

Diethylenetriaminepentaacetic acid 2.0

1-Hydroxyethylidene-1,1-diphosphonic acid 3.0

Sodium sulphite 4.0

Potassium carbonate 30.0

Potassium bromide 1.4

Potassium iodide 1.5 mg

Hydroxylamine sulfate 2,4

4-[N-Ethyl-N-(β-hydroxyethyl)amino]-2- methylaniline sulfate 4.5

Water to 1.0 l

pH10.05

Bleach-fixing solution: (g)

Iron ammonium ethylenediaminetetraacetate (dihydrate) 50.0

Disodium ethylenediaminetetraacetate 5.0

Sodium sulphite 12.0

aqueous ammonium thiosulfate solution (70%) 260.0 ml

Acetic acid (98%) 5.0 ml

Bleaching accelerator 0.01 mol

Water to 1.0 l

pH6.0

Washing solution:

Tap water was passed through a mixed bed column filled with a strong acidic H+ type cation exchange resin (Amberlite IR-120B, available from Rohm & Haas Co.) and a strong basic O- type anion exchange resin (Amberlite IR-400) to adjust the calcium and magnesium concentrations to 3 mg/L or less. Then, 20 mg/L of sodium isocyanuric dichloride and 1.5 g/L of sodium sulfate were added. The pH of the solution fell within the range of 6.5 to 7.5.

Stabilization solution: (g)

Formalin (37%) 2.0 ml

Polyoxyethylene p-monononylphenyl ether (average degree of polymerization = 10) 0.3

Disodium ethylenediaminetetraacetic acid 0.05

Water to 1.0 l

pH 5.0 to 8.0

Inventive samples 302 to 305 gave the same good results as in Example 3 after being subjected to the above processing.

EXAMPLE 8

Sample 401 of Comparative Example and Inventive Samples 402 to 404 obtained in Example 4 were exposed by the same method as in Example 4 and then processed using an automatic developing machine.

The processing method and the compositions of the processing solutions were the same as in Example 7. Inventive samples 402 to 404 gave the same good results as in Example 4 after being subjected to the above processing.

EXAMPLE 9 (comparative example)

A plurality of layers having the following compositions were coated on a primed triacetylcellulose film support to prepare Sample 901 as a multilayer color photosensitive material.

Composition of the light-sensitive layers:

Numbers corresponding to the respective components indicate coating amounts in units of g/m², except that the silver halide and colloidal silver are given in a coating amount converted to silver and the coating amounts of the sensitizing dyes are given in units of moles per mole of silver halide in the same layer.

SAMPLE 901 Layer 1: Antihalation Layer

Black colloidal silver Silver 0.18

Gelatin 1.40

Layer 2: Intermediate layer

2,5-Di-t-pentadecylhydroquinone 0.18

EX-1 0.07

EX-3 0.02

EX-12 0.002

U-1 0.06

U-2 0.08

U-3 0.10

HBS-1 0.10

HBS-2 0.02

Gelatin 1.04

Layer 3: First red-sensitive emulsion layer

Emulsion A Silver 0.25

Emulsion B Silver 0.25

Sensitizing dye I 6.9 x 10⊃min;⊃5;

Sensitizing dye II 1.8 x 10⊃min;⊃5;

Sensitizing dye III 3.1 x 10⊃min;⊃4;

EX-2 0.335

EX-10 0.020

Gelatin 0.87

Layer 4: Second red-sensitive emulsion layer

Emulsion C Silver 1.0

Sensitizing dye I 5.1 x 10⊃min;⊃5;

Sensitizing dye II 1.4 x 10⊃min;⊃5;

Sensitizing dye III 2.3 x 10⊃min;⊃4;

EX-2 0.400

EX-3 0.050

EX-10 0.015

Gelatine 1.30

Layer 3: Third red-sensitive emulsion layer

Emulsion D Silver 1.60

Sensitizing dye I 5.4 x 10⊃min;⊃5;

Sensitizing dye II 1.4 x 10⊃min;⊃5;

Sensitizing dye III 2.4 x 10⊃min;⊃4;

EX-3 0.010

EX-4 0.080

EX-2 0.097

HBS-1 0.22

HBS-2 0.10

Gelatin 1.63

Layer 6: Intermediate layer

EX-5 0.040

HBS-1 0.020

Gelatin 0.80

Layer 7: First green-sensitive emulsion layer

Emulsion A Silver 0.15

Emulsion B Silver 0.15

Sensitizing dye V 3.0 x 10⊃min;⊃5;

Sensitizing dye VI 1.0 x 10⊃min;⊃4;

Sensitizing dye VII 3.8 x 10⊃min;⊃4;

EX-6 0.260

EX-1 0.021

EX-7 0.030

EX-8 0.025

HBS-1 0.100

HBS-3 0.010

Gelatin 0.63

Layer 8: Second green-sensitive emulsion layer

Emulsion C Silver 0.45

Sensitizing dye V 2.1 x 10⊃min;⊃5;

Sensitizing dye VI 7.0 x 10⊃min;⊃4;

Sensitizing dye VII 2.6 x 10⊃min;⊃4;

EX-6 0.094

EX-8 0.026

EX-7 0.026

HBS-1 0.160

HBS-3 0.008

Gelatin 0.50

Layer 9: Third green-sensitive emulsion layer

Emulsion (monodisperse silver iodobromide emulsion III in Example 3) Silver 1.2

Sensitizing dye I 3.5 x 10⊃min;⊃5;

Sensitizing dye II 8.0 x 10⊃min;⊃5;

Sensitizing dye III 3.0 x 10⊃min;⊃4;

EX-13 0.015

EX-11 0.100

EX-1 0.025

HBS-1 0.25

HBS-2 0.10

Gelatin 1.54

Layer 10: Yellow filter layer

Yellow colloidal silver Silver 0.05

EX-5 0.08

HBS-1 0.03

Gelatin 0.95

Layer 11: First blue-sensitive emulsion layer

Emulsion A Silver 0.08

Emulsion B Silver 0.07

Emulsion E Silver 0.07

Sensitizing dye VIII 3.5 x 10⊃min;⊃4;

EX-9 0.721

EX-8 0.042

HBS-1 0.28

Gelatin 1.10

Layer 12: Second blue-sensitive emulsion layer

Emulsion F Silver 0.45

Sensitizing dye VIII 2.1 x 10⊃min;⊃4;

EX-9 0.154

EX-10 0.007

HBS-1 0.05

Gelatin 0.78

Layer 13: Third blue-sensitive emulsion layer

Emulsion G Silver 0.77

Sensitizing dye VIII 2.2 x 10⊃min;⊃4;

EX-9 0.20

HBS-1 0.07

Gelatin 0.69

Layer 14: First protective layer

Emulsion H Silver 0.5

U-4 0.11

U-5 0.17

HBS-1 0.05

Gelatin 1.00

Layer 15: Second protective layer

Polymethylacrylate grains (grain size = about 1.5 µm) 0.54

S-1 0.20

Gelatine 1.20

In addition to the above components, a gelatin hardener H-1 and/or a surfactant were added to each layer. The structures of the compounds used are listed in Table D presented later.

Emulsions A to H are silver iodobromide emulsions. The average AgI contents of these emulsions and the like are listed in the table below. TABLE (EMULSIONS A - H) Average AgI content (%) Average grain size (µm) Diameter/thickness ratio Silver quantity ratio (AgI content (%)) Emulsion core/middle/shell Triple structure grain core/shell Double structure horn

Samples 902 to 905 were prepared by the same procedures as Sample 901, except that the emulsion of Layer 9 was replaced by an emulsion obtained by adding thiosulfonic acid compounds and reduction sensitizers during grain formation as in the case of Em-102 to Em-113.

These samples were subjected to sensitometric exposure and color development using the same procedure as in Example 3.

The densities of the processed samples were measured using a green filter. The measurement results are summarized in Table 9-1.

The photographic properties are represented by the sensitivity of a green-sensitive layer as a relative sensitivity assuming that the sensitivity of the sample was 901 100. TABLE 9-1 Layer Monodisperse Silver Iodobromide Emulsion III Green Sensitive Layer Thiosulfonic Acid Reduction Sensitizer Sample No. Compound Addition Amount (per mole Ag) Fog Sensitivity Invention

As can be seen from Table 9-1, in the emulsions according to the invention, the effect of increasing the sensitivity occurred almost without increasing the fog.

EXAMPLE 10

A series of layers having the following compositions were coated on a primed cellulose triacetate film support to prepare Sample 1001 as a multilayer color photosensitive material.

Compositions of the light-sensitive layers:

The coating amounts of silver halide and colloidal silver are given in units of g/m² of silver, those of couplers, additives and gelatin in units of g/m², and those of sensitizing dyes by the number of moles per mole of silver halide in the same layer.

Layer 1: Antihalation Layer

Black colloidal silver Silver coating amount 0.2

Gelatin 2.2

UV-1 0.1

UV-2 0.2

Cpd-1 0.05

Solv-1 0.01

Solv-2 0.01

Solv-3 0.08

Layer 2: Intermediate layer

Fine silver bromide grains (equivalent sphere diameter = 0.07 µm) Silver coating amount 0.15

Gelatin 19

ExC-4 0.03

Cpd-2 0.2

Layer 3: First red-sensitive emulsion layer

Silver iodobromide emulsion (AgI = 8.5 mol.%, AgI-rich inside, equivalent sphere diameter = 1.0 µm, coefficient of variation of equivalent sphere diameter = 25%, tabular grains, diameter/thickness ratio = 3.0) Silver coating amount 0.42

Silver iodobromide emulsion (AgI = 4.0 mol%, AgI-rich inside, equivalent sphere diameter = 0.4 µm, coefficient of variation of equivalent sphere diameter = 22%, tetradecahedral grains) Silver coating amount 0.33

Gelatin 1.0

ExS-1 4.5 x 10-4

ExS-2 1.5 x 10⊃min;⊃4;

ExS-3 0.4 x 10⊃min;⊃4;

ExC-1 0.40

ExC-2 0.11

ExC-3 0.009

ExC-4 0.023

Solv-1 0.24

Layer 4: Second red-sensitive emulsion layer

Silver iodobromide emulsion (AgI = 8.5 mol.%, AgI-rich inside, equivalent sphere diameter = 1.0 µm, coefficient of variation of equivalent sphere diameter = 25%, tabular grains, diameter/thickness ratio = 3.0) Silver coating amount 0.55

Gelatin 0.7

ExS-1 3 x 10⊃min;⊃4;

ExS-2 1 x 10⊃min;⊃4;

ExS-3 0.3 x 10⊃min;⊃4;

ExC-1 0.10

ExC-2 0.05

ExC-4 0.25

Solv-1 0.20

Layer 5: Third red-sensitive emulsion layer

Silver iodobromide emulsion (AgI = 11.3 mol.%, AgI-rich inside, equivalent sphere diameter = 1.4 µm, coefficient of variation of equivalent sphere diameter = 28%, tabular grains, diameter/thickness ratio = 6.0) Silver coating amount 1.29

Gelatin 0.6

ExS-1 2 x 10⊃min;⊃4;

ExS-2 0.6 x 10-4

ExS-3 0.2 x 10⊃min;⊃4;

ExC-2 0.08

ExC-4 0.01

ExC-5 0.06

Solv-1 0.12

Solv-2 0.12

Layer 6: Intermediate layer

Gelatin 1.0

Cpd-4 011

Solv-1 0.1

Layer 7: First green-sensitive emulsion layer

Silver iodobromide emulsion (AgI = 8.5 mol.%, AgI-rich inside, equivalent sphere diameter = 1.0 µm, coefficient of variation of equivalent sphere diameter = 25%, tabular grains, diameter/thickness ratio = 3.0) Silver coating amount 0.28

Silver iodobromide emulsion (AgI = 4.0 mol.%, AgI-rich inside, equivalent sphere diameter = 0.7 µm, coefficient of variation of equivalent sphere diameter = 38%, tabular grains, diameter/thickness ratio = 2.0) Silver coating amount 1.0

Gelatin 1.2

ExS-5 5 x 10⊃min;⊃4;

ExS-6 2 x 10⊃min;⊃4;

ExS-7 1 x 10⊃min;⊃4;

ExM-1 0.50

ExM-2 0.10

ExM-5 0.03

Solv-1 0.2

Solv-4 0.03

Layer 8: Second green-sensitive emulsion layer

Silver iodobromide emulsion (AgI = 8.5 mol.%, Inner iodide-rich, equivalent sphere diameter = 1.0 µm, coefficient of variation of equivalent sphere diameter = 25%, tabular grains, diameter/thickness ratio = 3.0) Silver coating amount 0.47

Gelatin 0.35

ExS-5 3.5 x 10⊃min;⊃4;

ExS-6 1.4 x 10-4

ExS-7 0.7 x 10-4

ExM-1 0.12

ExM-3 0.01

Solv-1 0.15

Solv-4 0.03

Layer 9: Intermediate layer

Gelatin 0.5

Layer 10: Third green-sensitive emulsion layer

Monodisperse silver iodobromide emulsion II from Example 2 Silver coating amount 1.3

Gelatin 0.8

ExS-5 2 x 10⊃min;⊃4;

ExS-6 0.8 x 10-4

ExS-7 0.8 x 10-4

ExM-3 0.01

ExM-4 0.04

ExC-4 0.005

Cpd-5 0.01

Solv-1 0.2

Layer 11: Yellow filter layer

Cpd-3 0.05

Gelatin 0.5

Solv-1 0.1

Layer 12: Intermediate layer

Gelatin 0.5

Cpd-2 0.1

Layer 13. First blue-sensitive emulsion layer

Silver iodobromide emulsion (AgI = 10 mol.%, interiorly iodide-rich, equivalent sphere diameter = 0.7 µm, coefficient of variation of equivalent sphere diameter = 14%, tetradecahedral grains) Silver coating amount 0.1

Silver iodobromide emulsion (AgI = 4.0 mol.%, interiorly iodide-rich, equivalent sphere diameter = 0.4 µm, coefficient of variation of equivalent sphere diameter = 22%, tetradecahedral grains) Silver coating amount 0.05

Gelatin 1,

ExS-9 3 x 10⊃min;⊃4;

ExY-1 0.6

ExY-2 0.02

Solv-1 0.15

Layer 14: Second blue-sensitive emulsion layer

Silver iodobromide emulsion (AgI = 19.0 mol.%, AgI-rich inside, equivalent sphere diameter = 1.0 µm, coefficient of variation of equivalent sphere diameter = 16%, tetradecahedral grains) Silver coating amount 0.19

Gelatin 0.3

ExS-9 2 x 10⊃min;⊃4;

ExY-1 0.22

Solv-1 0.07

Layer 15: Intermediate layer

Fine silver iodobromide grains (AgI = 2 mol.%, homogeneous, equivalent sphere diameter = 0.13 µm) Silver coating amount 0.2

Gelatin 0.36

Layer 16: Third blue-sensitive emulsion layer

Silver iodobromide emulsion (AgI = 14.0 mol.%, AgI-rich inside, equivalent sphere diameter = 1.7 µm, coefficient of variation of equivalent sphere diameter = 28%, tabular grains, diameter/thickness ratio = 5.0) Silver coating amount 1.4

Gelatin 0.5

ExS-9 1.5 x 10⊃min;⊃4;

ExY-1 0.2

Solv-1 0.07

Layer 17: First protective layer

Gelatin 1.8

UV-1 0.1

UV-2 0.2

Solv-1 0.01

Solv-2 0.01

Layer 18: Second protective layer

Fine silver chloride grains (equivalent sphere diameter = 0.07 µm) Silver coating amount 0.36

Gelatin 0.7

Polymethyl methacrylate grains (diameter = 1.5 µm) 0.2

W-1 0.02

H-1 0.4

Cpd-6 1.0

In addition to the above compositions, B-1 (total amount = 0.20 g/m2), 1,2-benzisothiazolin-3-one (average amount about 200 ppm with respect to gelatin), n-butyl- p-hydroxybenzoate (ditto, about 1000 ppm) and 2-phenoxyethanol (ditto, about 1000 ppm) were added to each layer. Formulas of the compounds used are listed in Table E.

Samples 1002 to 1004 were prepared by the same procedures as Sample 1001, except that the emulsion of Layer 10 was replaced by an emulsion prepared by adding thiosulfonic acid compounds and the reduction sensitizer L-ascorbic acid during grain formation as in the case of Em-204 to Em-206.

These samples were subjected to sensitometric exposure and then color development following the same steps as in Example 4.

The densities of the processed samples were measured using a green filter. The results obtained are summarized in Table 10-1.

The photographic properties are given by the sensitivity of a green-sensitive layer as a relative sensitivity assuming that the sensitivity of the sample is 1001 100. TABLE 10-1 Layer Monodisperse Silver Iodobromide Emulsion III Green Sensitive Layer Thiosulfonic Acid Compound L-Ascorbic Acid Sample No. Compound Addition Amount (per mole Ag) Fog Sensitivity Invention

As shown in Table 10-1, the emulsions of the present invention exhibited an effect of increasing the sensitivity with almost no increase in fog. When the samples were stored according to the same procedure as in Example 2 and their photographic properties were checked, the fog of Sample 1001 was significantly increased while its sensitivity was reduced. In contrast, Samples 1002 to 1004 exhibited better photographic properties than Comparative Example 1001.

EXAMPLE 11 (comparative example)

Samples 301 to 305 of Example 3 and 901 to 905 of Example 9 were exposed by the same procedures as in Examples 3, 9 and processed as follows using an automatic developing machine. As a result, it was confirmed that the samples of the present invention provided similarly good effects as in Examples 3 and 9. TABLE 11 Step Processing time Processing temperature Amount of replenisher solution* Tank volume Colour development Bleaching Fixation Washing Stabilisation Drying Countercurrent Replenishment from to *Amount per 1 m sample

The compositions of the processing solutions are summarized below: Colour developer Mother solution (g) Replenisher solution (g) Diethylenetriaminepentaacetic acid 1-Hydroxyethylidene-1,1-diphosphonic acid Sodium sulphite Potassium carbonate Potassium bromide Potassium iodide Hydroxylamine sulphate 4-[N-ethyl-N-(β-hydroxyethyl)-amino]-2-methylaniline sulphate Water on Bleaching solution Mother solution (g) Replenisher solution (g) 1,3-Diaminopropanetetraacetic acid iron ammonium monohydrate 1,3-Diaminopropanetetraacetic acid Ammonium bromide Ammonium nitrate ( %) Acetic acid ( %) Water on Fixing solution Mother solution (g) Replenisher solution (g) 1-Hydroxyethylidene-1,1-diphosphonic acid Ammonium sulphite Aqueous ammonium thiosulphate solution ( g/l) Water on

Wash water: common for mother solution and replenisher solution

Tap water was passed through a mixed bed column filled with a strong acidic H+ type cation exchange resin (Amberlite IR-120B, available from Rohm & Haas Co.) and a strong basic OH- type anion exchange resin (Amberlite IR-400) to adjust the calcium and magnesium concentrations to 3 mg/L or less. Then, 20 mg/L of sodium isocyanuric dichloride and 1.5 g/L of sodium sulfate were added. The pH of the solution fell within the range of 6.5 to 7.5. Stabilizing solution Mother solution (g) Replenisher solution (g) Triethanolamine Formalin ( %) Polyoxyethylene-p-monononylphenyl ether (average degree of polymerization = ) Disodium ethylenediaminetetraacetate Water to TABLE A x : y = 1/1 (molar ratio) TABLE B n : m : m' = 2 : 1 : 1 (weight ratio) Molecular weight: about 40,000 n/m/m' = 50/25/25 (wt.%) Average molecular weight: about 30,000 (Numbers mean weight ratio) TABLE C TABLE D n =50 m =25 m' =25 Mol.Wt. about 20,000 Tricresyl phosphate Di-n-butyl phthalate Sensitizing dye Sensitizing dye Sensitizing dye TABLE E x/y=7/3 (weight ratio) n : m : l = 2 = 2 : 1 : 1 (weight ratio) Average molecular weight: 40,000

Claims (16)

1. Light-sensitive silver halide photographic material comprising a support and at least one silver halide emulsion layer thereon, said silver halide emulsion layer containing a monodisperse silver halide emulsion whose grains are of the core/shell type or double structure type with different silver halide compositions in their core and surface regions and which are reduction sensitized by ascorbic acid or an ascorbic acid derivative during the preparation of the silver halide emulsion, provided that the silver halide grains contain less than 5 mol% silver iodide on their surface. 2. Light-sensitive silver halide photographic material according to claim 1, characterized in that the silver halide emulsion is a monodisperse silver halide emulsion which has been reduction sensitized in the presence of at least one type of thiosulfonic acid compound having the formula (I), (II) or (III): R-SO₂S-M (I) R-SO₂S-R¹ (II) RSO₂S-Lm-SSO₂-R² (III) wherein R, R¹ and R² may be the same or different and represent an aliphatic group, an aromatic group or a heterocyclic group, M represents a cation, L represents a divalent linking group, m represents 0 or 1, compounds with the formulas (I) to (III) may be polymers containing as a basic unit divalent groups derived from compounds with the formulas (I) to (III) and, if possible, R, R¹, R² and L may be linked to each other to form a ring. 3. Light-sensitive silver halide photographic material according to claim 2, characterized in that the thiosulfonic acid compound is a compound having the formula (I). 4. Light-sensitive silver halide photographic material according to claim 2, characterized in that the thiosulfonic acid compound is included in an amount of 10⁻⁶ to 10⁻² mol per mol of silver halide. 5. Light-sensitive silver halide photographic material according to claim 4, characterized in that the thiosulfonic acid compound is included in an amount of 10⁻⁵ to 10⁻³ mol per mol of silver halide. 6. Light-sensitive photographic silver halide material according to claim 1, characterized in that the ascorbic acid or its derivative is present in an amount of 5 x 10⁻⁴ to 1 x 10⁻² mol per mol of silver halide. 7. Light-sensitive photographic silver halide material according to claim 6, characterized in that the ascorbic acid or its derivative is present in an amount of 1 x 10⁻³ to 1 x 10⁻² mol per mol of silver halide. 8. A silver halide photographic light-sensitive material according to claim 1, characterized in that the monodisperse silver halide emulsion comprises octahedral grains having a (111) face and tetradecahedral grains having both a (100) face and a (111) face in a single grain. 9. Light-sensitive silver halide photographic material according to claim 1, characterized in that in said monodisperse silver halide emulsion the weight of the silver halide grains falling within the grain size range of -20 to +20% of the most common grain size is not less than 60% of the total weight of the silver halide grains. 10. A silver halide light-sensitive material according to claim 9, characterized in that the weight of the silver halide grains contained in a grain size range of -20 to +20% of the most common grain size, make up not less than 70% of the total weight of the silver halide grains. 11. A silver halide light-sensitive material according to claim 9, characterized in that the weight of the silver halide grains falling within a grain size range of -20 to +20% of the most common grain size is not less than 80% of the total weight of the silver halide grains. 12. Light-sensitive silver halide photographic material according to claim 1, characterized in that two or more types of monodisperse silver halide emulsions with different maximum grain size frequencies are mixed in a single layer or applied in different layers. 13. Light-sensitive silver halide photographic material according to claim 1, characterized in that the material is a light-sensitive color photographic material. 14. A silver halide photographic light-sensitive material according to claim 1, which contains at least one coupler selected from the group consisting of a DIR coupler, a DIR coupler-releasing coupler and a DIR redox compound-releasing coupler. 15. A silver halide photographic light-sensitive material according to claim 1, wherein the ascorbic acid derivative is at least one of the following: L-ascorbic acid Sodium L-ascorbate Potassium L-ascorbate DL-ascorbic acid Sodium D-ascorbate L-Ascorbyl-6-acetat L-Ascorbyl-6-palmitate L-ascorbyl-6-benzoate L-ascorbyl-5,6-diacetate and L-Ascorbyl-5,6-O-isopropyliden 16. A silver halide photographic light-sensitive material according to claim 1, wherein reduction sensitization of the grains by ascorbic acid or an ascorbic acid derivative is carried out during grain formation.