EP0070181A1

EP0070181A1 - Silver halide light-sensitive color photographic material

Info

Publication number: EP0070181A1
Application number: EP82303646A
Authority: EP
Inventors: Kiyoshi Yamashita; Toshifumi Iijima
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 1981-07-10
Filing date: 1982-07-12
Publication date: 1983-01-19

Abstract

A silver halide light-sensitive color photographic material comprising a blue-sensitive, a green-sensitive and a red-sensitive negative type light-sensitive silver halide emulsion layers provided on a support, at least 80% of the silver halide grains contained in the light-sensitive silver halide emulsion layer farthest from said support or in the green-sensitive silver halide emulsion layer being constituted by regular-crystal silver halide grains.

The color photographic material according to the present invention exhibits an improved sharpness of the dye image formed therein.

Description

This invention relates to a silver halide light-sensitive color photographic material, and more particularly to a silver halide light-sensitive color photographic material which is excellent in sharpness of the dye image formed.
Generally, a silver halide light-sensitive color photographic material comprises a plurality of light-sensitive silver halide emulsion layers uniformly applied on a support made of for example cellulose triacetate, polyethylene terephthalate or the like. Each of these emulsion layers has a dry film thickness of several microns and exhibits different color sensitivity. These light-sensitive silver halide emulsion layers contain many silver halide grains which have a grain size approximately corresponding to the wavelength of visible ray and exhibit various crystal habits, and which are dispersed in a hydrophilic colloid exhibiting a refractive index smaller than that of a silver halide, such as gelatin. As already known in this field, when a visible ray is applied perpendicularly to the surface of a light-sensitive silver halide emulsion layer of this type, the visible ray is scattered by the silver halide grains in the layer.
This phenomenon is interpreted to occur because the grain size is approximately equal to the wavelength of the visible ray and because the refractive indices of the grains and the binder are different from each other. The degree of the scattering differs according to the number of grains contained in the unit volume of the light-sensitive silver halide emulsion layer, grain size, grain size distribution, difference between the refractive indices of the silver halide grains and the binder. Thus, even when a visible incident ray impinges upon the light-sensitive silver halide emulsion layer at right angles, it is scattered in the layer, adversely affecting the sharpness of the image formed therein.
The above-mentioned problem is aggravated when an image is magnification-projected or enlarged in printing. As a result, the image becomes unsharp. For example, the contour of an edge image or details of a texture image become unsharp, and the quality of the dye image is affected detrimentally.
Various methods have been proposed to relieve the deterioration in the image sharpness due to scattering of light.
For example, as an effective method of improving image sharpness in the green-sensitive silver halide emulsion layer, it has been proposed to minimize diffusion of scattered light in the direction parallel to the surface of the silver halide emulsion layer. For this purpose, the film thickness of the silver halide emulsion layer is minimized by reducing the proportion of silver halide grains with respect to gelatin in the light-sensitive silver halide emulsion layer, reducing the average crystal size of the silver halide grains in the light-sensitive silver halide emulsion layer used as the uppermost layer, or by decreasing the amount of the binder used in the light-sensitive silver halide emulsion. However, these methods have serious drawbacks. Namely, sensitivity of an emulsion layer generally deteriorates when the grain sizes of silver halide grains are reduced. Further, if the amount of the binder contained in the emulsion layer is substantially reduced, the amount of the coupler which can be added to the emulsion layer also decreases, resulting in a low sensitivity of the emulsion.
On the other hand, it is also known to apply a green-sensitive silver halide emulsion layer, which forms a magenta color forming dye image exhibiting a high relative luminosity, as the uppermost layer of the light-sensitive color photographic material. However, this method also presents a serious problem with regard to the basic performance of the color light-sensitive material. Namely, the uppermost layer of the green-sensitive silver halide emulsion is also sensitive to the blue light region which is the sensitive region intrinsic to the silver halide emulsion. This fact is unfavorable to the green-sensitive silver halide. Normally, it is desirable that only the blue-sensitive silver halide emulsion layer be sensitive to blue light. This phenomenon of the green-sensitive silver halide emulsion results in fatal defects in the color reproduction of the color photosensitive material.
An object of the present invention is to provide a silver halide light-sensitive color photographic material exhibiting an improved sharpness of the dye image formed therein.
Namely, the present invention relates to a silver halide light-sensitive color photographic material comprising blue-sensitive, green-sensitive, and red-sensitive negative type light-sensitive silver halide emulsion layers provided on a support, characterized in that at least 80% of silver halide grains contained in the light-sensitive silver halide emulsion layer farthest from said support or in the green-sensitive silver halide emulsion layer are constituted by regular-crystal silver halide grains.
The silver halide light-sensitive color photographic material in accordance with the present invention exhibits an improved sharpness of the dye image formed therein.
The term "negative type light-sensitive silver halide emulsion" as used herein has a meaning opposite to the direct positive type silver halide emulsion. Namely, the negative type silver halide emulsion in the present invention means a silver halide emulsion which has the sensitive nuclei at the surfaces of the silver halide grains and which yields blackened silver in proportion to the lightness of the object when developed with a surface developing solution after the exposure.
The silver halide light-sensitive color photographic material in accordance with the present invention will hereinbelow be described in more detail.
The regular-crystal silver halide grains used in the silver halide light-sensitive photographic material in accordance with the present invention means silver halide crystal grains having a regular form, in which the outer crystal habit essentially consists only of [100] face and/or [111] face. Thus it is used as a concept opposite to the twinned crystal. Typical regular-crystal silver halide grains in the present invention are those having a regular cubic, octahedral or tetradecahedral form. In the light-sensitive silver halide emulsion layer containing the regular-crystal silver halide grains in accordance with the present invention, at least 80% of all silver halide grains contained therein are constituted by the regular-crystal silver halide grains defined above.
In a preferred embodiment of the present invention, at least 80% of the silver halide grains contained in the light-sensitive silver halide emulsion layer located at the position farthest from the support are constituted by the regular-crystal silver halide grains defined above.
In another preferred embodiment of the present invention, at least 80% of the silver halide grains contained in the light-sensitive silver halide emulsion layer, which is sensitive to green light, are constituted by the above-mentioned regular-crystal silver halide grains.
In the present invention, when the above-mentioned green-sensitive silver halide emulsion layer is not located at the position farthest from the support, it is further preferable that at least 80% of the total silver halide grains contained in each of said green-sensitive silver halide emulsion layer and said farthest light-sensitive silver halide emulsion layer are constituted by the above-mentioned regular-crystal silver halide grains.
In one of the most preferred embodiments of the present invention, at least 80% of the silver halide grains contained in all light-sensitive silver halide emulsion layers constituting the silver halide light-sensitive color photographic material in accordance with the present invention are constituted by the regular-crystal silver halide grains.
The silver halide grains used in the silver halide light-sensitive photographic material in accordance with the present invention may be prepared by the acid process, neutral process or ammonia process.
It is also possible to prepare seed crystals by the acid process, and grow them up to the predetermined size by the ammonia process which gives a high growth rate. When growing the silver halide grains, it is desirable that the pH, EAg or the like in the reactor are controlled, and silver ions and halide ions are both poured simultaneously and sequentially and mixed in quantities matching the growth rate of silver halide crystals, as described for example in Japanese Provisional Patent Publication No. 48521/1979, which is so-called "double-jet" method.
In the preparation of the silver halide grains used in the present invention, ions of noble metals such as Ir, Rh, Pt and Au may be added in the course of the grain growth so as to include them in the interiors of the grains, or reduction sensitization nuclei may be formed in the interiors of the grains by using a low pAg atmosphere or an appropriate reducing agent.
The silver halide emulsions used in the present invention may be adjusted to a pAg value or an ion concentration suitable for chemical sensitization by using an appropriate method after the growth of the silver halide grains is finished. For this purpose, for example, the aggregation method and the noodle water-washing method as described in Research Disclosure No. 17643 may be used.
In the present invention, the regular-crystal silver halide emulsion may be used without changing its crystal size distribution, or two or more regular-crystal emulsions having different average crystal sizes may be blended together to obtain a desired gradient of characteristic curve at an arbitrary point of time after the formation of grains. It is preferable, however, to blend them after the chemical ripening.
The light-sensitive silver halide emulsion layer located at the position farthest from the support, or the green-sensitive silver halide emulsion layer in the silver halide light-sensitive color photographic material in accordance with the present invention may contain silver halide grains other than the regular crystals, for example twinned- crystal silver halide grains, in an amount not exceeding 20% of the total grains contained in the layer. However, it is preferable that the content of silver halide grains other than the regular crystals be limited to 10% or less, and it is more preferable that the layer is substantially free from silver halide grains other than the regular crystals.
In the regular-crystal silver halide emulsion contained in the silver halide light-sensitive color photographic material in accordance with the present invention, the cubic, octahedral and tetradecahedral crystal grains may be used alone or two or more thereof may be mixed in any proportions. However, it is preferable that the proportions of the octahedral grains and/or tetradecahedral grains be larger than that of the cubic grains, and it is more preferable that the crystal grains be constituted only by octahedral grains and/or tetradecahedral grains.
In the present invention, there is no limitation regarding the composition of the silver halides in the silver halide emulsions, and a composition usually employed may be used. For example, in a negative emulsion for general photography, a composition containing silver bromide as the main constituent and optionally 12 mol % or less of silver iodide and 10 mol % or less of silver chloride is preferably used. On the other hand, for use in printing in which excellent developing characteristics are required and a relatively low sensitivity is permitted, silver chlorobromide emulsions, silver chloroiodobromide emulsions or the like containing silver chlorobromide or silver chloride as the main constituent may be used.
When two or more emulsions having different average crystal sizes are used in combination in the present invention, it is preferable that each emulsion be chemically sensitized in a manner suitable thereto.
The chemical sensitization may be conducted by a known method such as sulfur sensitization, gold sensitization, selenium sensitization, and reduction sensitization. Two or more of these sensitization methods may be combined. The reaction rate differs according to the crystal size of the silver halide, and the respective emulsions cannot necessarily exhibit their maximum reaction rates if they are sensitized by the same method or after blended together instead of being individually sensitized.
In the present invention, the sulfur sensitization may be conducted by using for example sodium thiosulfate, thiourea, allyl thiourea or the like. The gold sensitization can be conducted by using for example sodium chloroaurate, potassium aurothio- cyanate or the like. It is also possible to conduct gold-sulfur chemical sensitization by using at least one sulfur sensitizing agent and at least one gold sensitizing agent listed above. In this case, ammonium thiocyanate or the like may further be added.
In addition to the aforesaid chemical sensitization methods, the selenium sensitization method may also be applied for the silver halide emulsions used in the present invention. For this purpose, methods using selenourea, N,N'-dimethylselenourea or the like, as described for example in U.S. Patent Nos. 1,574,944 and 3,591,385, Japanese Patent Publication Nos. 13849/1968 and 15748/1969 may be used.
Further, it is possible to conduct reduction sensitization according to the conventional procedure. This can be done for example by the ripening in a low pAg atmosphere or by using an appropriate reducing agent or an electromagnetic wave such as light and y-ray.
In the silver halide light-sensitive photographic material in accordance with the present invention, the two or more emulsions having different average crystal sizes may be applied as separate layers on the support or may be applied as one layer after mixing. The support used in this case may be of any known material for example a polyester film such as polyethylene terephthalate, a polyamide film, a polycarbonate film, a styrene film, baryta paper, or paper coated with a synthetic polymer.
The silver halide light-sensitive color photographic material in accordance with the present invention is particularly suitable as the negative type silver halide color photographic material for the purpose of taking a picture, which is required to exhibit a high sensitivity and a high image quality.
The hydrophilic colloid used to disperse the silver halide grains therein in accordance with the present invention is most preferably gelatin. However, for the purpose of improving the binder characteristics, it is also possible to use for example gelatin derivatives, other natural hydrophilic colloids such as albumin, casein, agar, gum arabic, alginic acid and its derivatives e.g. salts, amides and esters thereof, starch and its derivatives, cellulose derivatives such as cellulose ethers, partially hydrolyzed cellulose acetate and carboxymethyl cellulose, and synthetic hydrophilic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, homopolymers and copolymers of acrylic acid and methacrylic acid or their derivatives e.g. esters, amides and nitriles thereof, and vinyl polymers e.g. vinyl ethers and vinyl esters.
The silver halide emulsions used in the silver halide light-sensitive photographic material in accordance with the present invention may also contain stabilizers and fog restrainers as described for example in U.S. Patent Nos. 2,444,607, 2,716,062, 3,512,982, and 3,342,596, German Patent Nos. 1,189,380, 205,862 and 211,841, Japanese Patent Publication Nos. 4183/1968 and 2825/1964, and Japanese Provisional Patent Publication Nos. 22626/1975 and 25218/1975. Examples of particularly preferable compounds used for this purpose are 5,6-trimethylene-7-hydroxy-8-triazolo(l,5-a)pyrimidine, 5,6-tetramethylene-7-hydroxy-8-triazolo(1,5-a)pyrimidine, 5-methyl-7-hydroxy-8-triazolo(l,5-a)pyrimidine, 7-hydroxy-8-triazolo(1,5-a)pyrimidine, gallates such as isoamyl gallate, dodecyl gallate, propyl gallate and sodium gallate, mercaptans such as 1-phenyl-5-mercaptotetrazole and 2-mercaptobenzothiazole, benzotriazoles such as 5-bromobenzotriazole and 4-methylbenzotriazole, and benzoimidazoles such as 6-nitrobenzo- imidazole.
The silver halide emulsions in the present invention may be subjected to the spectral sensitization by using known spectral sensitizing dyes such as cyanine dye and merocyanine dye according to the conventional procedure. For example, for the regular region, it is possible to use sensitizing dyes as described in Japanese Provisional Patent Publication Nos. 2756/1980 and 14743/1₉₈₀. For the ortho region, the sensitizing dyes as described in Japanese Provisional Patent Publication Nos. 56425/1973 and 31228/1976, and Japanese Patent Publication No. 25379/1972 may be used. These dyes may be used alone or in combination with one another. Further, the spectral sensitization for the long wavelength range can be conducted by using a cyanine dye having a longer methine group as described in Japanese Provisional Patent Publication No. 126140/1976. It is also possible to conduct the supersensitization by use of a combination of dyes.
The coating composition for the silver halide photosensitive material in accordance with the present invention may contain photographic hardeners usually used in this field such as for example aldehydes, aziridines as described for example in PB Report 19,921, U.S. Patent Nos. 2,950,197, 2,964,404, 2,983,611 and 3,271,175, Japanese Patent Publication No. 40898/1971 and Japanese Provisional Patent Publication No. 91315/1975, isoxazoles as described e.g. in U.S. Patent No. 331,609, epoxy compounds as described e.g. in U.S. Patent No. 3,047,394, West German Patent No. 1,085,663, British Patent No. 1,033,518 and Japanese Patent Publication No. 35495/ 1973, vinyl sulfones as described e.g. in PB Report 19,920, West German Patent No. 1,100,942, British Patent No. 1,251,091, Japanese Patent Publication No. 13563/1974, Japanese Provisional Patent Publication No. 528/1975, U.S. Patent Nos. 353,964 and 3,490,911, acryloyls as described e.g. in U.S. Patent No.4,039,520 and U.S. Patent No. 3,640,720, carbodiimides as described e.g. in U.S. Patent No. 2,938,892, Japanese Patent Publication No. 38715/1971 and Japanese Provisional Patent Publication No. 107278/1975, other hardeners such as maleimides, acetylenes, methane sulfonates, triazines and high-molecular hardeners. Further, the coating composition in accordance with the present invention may contain thickening agents as described e.g. in U.S. Patent No. 3,167,410 and Belgian Patent No. 558,143, gelatin plasticizers such as polyols as described e.g. in U.S. Patent No. 2,960,404, Japanese Patent Publication 4939/1968 and Japanese Provisional Patent Publication No. 63715/1973, and latices as described e.g. in U.S. Patent No. 766,976, French Patent No. 1,395,544 and Japanese Patent Publication No. 43125/1973, and matting agents as described e.g. in British Patent No. 1,221,980.
The composition for the silver halide light-sensitive photographic material in accordance with the present invention may contain a desired auxiliary such as saponin or a sulfosuccinic acid surface active agent as described e.g. in British Patent No. 548,532 and Japanese Provisional Patent Publication No. 46733/1974 or an anionic surface active agent as described e.g. in Japanese Patent Publication No. 18156/1968, U.S. Patent No. 3,514,293, French Patent No. 2,025,688 and Japanese Patent Publication No. 10247/1968.
In the present invention, dyes may be used in the layer which is below the emulsion layers in accordance with the present invention and which contacts the support. Further, for the purpose of improving image sharpness or reducing fog due to safelight, dyes may be added to the protective layer and/or the emulsion layers in accordance with the present invention and/or the non-photosensitive layer contacting the emulsion layer in accordance with the present invention. For this purpose, any of dyes known for this purpose may be used.
The emulsions in accordance with the present inven-. tion may be applied to the color light-sensitive material by using the technology and materials which are usually used for general color light-sensitive materials and the false color light-sensitive materials as described in Imaging No. 18-19 (1976). For example, a combination of cyan, magenta and yellow couplers may be added to the emulsions in accordance with the present invention, whose red, green and blue sensitivities have been adjusted.
Examples of useful couplers are open-chain methylene series yellow couplers, pyrazolone series magenta couplers, phenol or naphthol series cyan couplers. These couplers may be used in combination with colored couplers for auto masking, e.g. couplers having a split-off group, which has an azo lid as the bonding lid, bonded to the active point of the coupler; osazone compounds; development diffusing dye-releasing couplers; development inhibitor- releasing compounds, which release a development inhibitor by the reaction with the oxidized product of an aromatic primary amine developing agent and which embrace both DIR couplers forming a color by reacting with the oxidized product of the aromatic primary amine developing agent and DIR substances forming a colorless compound. These couplers may be incorporated into the silver halide color light-sensitive photographic material according to various procedures known for such couplers.
The silver halide light-sensitive photographic material in accordance with the present invention can be developed by the known methods usually employed. The bleach developing solution may be a usually employed developing solution containing e.g. hydroquinone, l-phenyl-3-pyrazolidone, N-methyl-p-aminophenol or p-phenylenediamine alone or in the form of a combination of two or more thereof. It is also possible to use other additives usually employed. In case the light-sensitive material is used for color photographic purpose, it can be color- developed by usual color development method.
A developing solution containing an aldehyde hardener can also be used for the silver halide light-sensitive material in accordance with the present invention. For example, it is possible to use developing solution known in the field of photography containing dialdehydes such as maleic dialdehyde, glutaric dialdehyde or their salts with sodium bisulfite.
The present invention will hereinafter be illustrated in further detail by the following non-limitative examples.

Example 1

Primitive emulsions 1, 2, 3 and 4 were prepared as described below.

(Primitive emulsion 1)

An aqueous ammoniacal silver nitrate solution and an aqueous alkali halide solution were admixed with an aqueous gelatin solution containing alkali halides at 50° C. over 15 minutes according to the usual double jet mixing method. In this way, a silver iodobromide emulsion having an average crystal size of 0.65 n and a standard deviation of 0.21 p and containing 5 mol % of silver iodide with the content of twinned crystals being 30%, was prepared.

(Primitive emulsion 2)

An aqueous ammoniacal silver nitrate solution and an aqueous alkali halide solution were admixed with an aqueous gelatin solution containing alkali halides at 40° C. over 83 minutes by maintaining the pAg value at 8.6 according to the pAg-controlled double jet mixing method. In this way, a silver iodobromide emulsion having an average crystal size of 0.65 p and a standard deviation of 0.154 µ and containing 5 mol % of essentially cubic silver iodide, with the content of twinned crystals being 12%, was obtained.

(Primitive emulsion 3)

An aqueous ammoniacal silver nitrate solution and an aqueous alkali halide solution were precipitated in an aqueous gelatin solution containing alkali halides at 40° C. over 105 minutes by maintaining the pAg value at 9.85 according to the pAg-controlled double jet mixing method. In this way, a silver iodobromide emulsion having an average grain size of 0.68 µ and a standard deviation of 0.142 p and containing 5 mol % of essentially octahedral silver iodide, with the content of twinned crystals being 12%, was obtained.

(Primitive emulsion 4)

An aqueous ammoniacal silver nitrate solution and an aqueous alkali halide solution were admixed with an aqueous gelatin solution containing alkali halides at 40° C. over 60 minutes by maintaining the pAg value at 9.5 and later 20 minutes the pAg value at 10.4 according to the pAg-controlled double jet mixing method. In this way, a silver iodobromide emulsion having an average crystal size of 0.65 µ and a standard deviation of 0.157 p and containing 5 mol % of essentially tetradecahedral silver iodide, with the content of twinned crystals being 12%, was obtained.
Thereafter, the layers described below were sequentially coated on a support in the following order. The support was a under-coated cellulose triacetate film. In this way, specimens 1 - 19 were prepared.

(Specimen 1)

Layer 1: Antihalation layer

An aqueous gelatin solution containing black colloidal silver dispersed therein was applied so as to obtain a dry film thickness of 2.0 µ.

Layer 2: Red-sensitive silver halide emulsion layer

The primitive emulsion 1 was chemically sensitized with a gold sensitizing agent and a sulfur sensitizing agent. Further, as the sensitizing dyes, anhydrous 9-ethyl-3,3'-di-(3-sulfopropyl)-4,5,4',5'-dibenzothiacarbocyanine hydroxide and anhydrous 5,5'-dichloro-9-ethyl-3,3'-di-(3-sulfopropyl)thiacarbo- cyanine hydroxide were added. Thereafter, 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene and 1-phenyl-5-mercaptotetrazole were added, followed by the addition of the dispersion (C-l) described hereinafter. The red-sensitive silver halide emulsion thus obtained was applied so as to obtain a dry film thickness of 4.5 µ.

Layer 3: Intermediate layer

An aqueous gelatin solution was applied to obtain a dry film thickness of 1.0 µ.

Layer 4: Green-sensitive silver halide emulsion layer

The primitive emulsion 1 was chemically sensitized with a gold sensitizing agent and a sulfur sensitizing agent. Further, as the sensitizing dyes, anhydrous 5,5'-dichloro-9-ethyl-3,3'-di(3-sulfopropyl) oxacarbocyanine hydroxide, anhydrous 5,5'-diphenyl-9-ethyl-3,3'-di-(3-sulfopropyl)oxacarbocyanine and anhydrous 9-ethyl-3,3'-di-(3-sulfopropyl)-5,6,5',6'-dibenzooxacarbocyanine hydroxide were added. Thereafter, 4-hydroxy-6-methyl-l,3,3a,7-tetrazaindene and 1-phenyl-5-mercaptotetrazole were added, followed by the addition of the dispersion (M-l) described hereinafter. The green-sensitive silver halide emulsion thus obtained was applied so as to obtain a dry film thickness of 4.5 µ.

Layer 5: Intermediate layer

An aqueous gelatin solution was applied so as to obtain a dry film thickness of 1.0 µ.

Layer 6: Yellow filter layer

An aqueous gelatin solution containing yellow colloidal silver and 2,5-di-tert.-octylhydroquinone dispersed therein was applied so as to obtain a dry film thickness of 1.2 µ.

Layer 7: Blue-sensitive silver halide emulsion layer

The primitive emulsion 1 was chemically sensitized with a gold sensitizing agent and a sulfur sensitizing agent. Further, 4-hydroxy-6-methyl-l,3,3a,7-tetrazaindene and 1-phenyl-5-mercaptotetrazole were added. Thereafter, the dispersion (Y-l) described later and 1,2-bisvinylsulfonylethane were added to prepare a blue-sensitive silver halide emulsion. The emulsion thus prepared was applied to obtain a dry film thickness of 5.0 µ.

Layer 8: Protective layer

An aqueous gelatin solution containing 1,2-bisvinylsulfonylethane was applied to obtain a dry film thickness of 1.2 µ.

(Specimen 2)

Layer 1: Antihalation layer (same as the layer 1 of specimen 1)

Layer 2: Red-sensitive silver halide emulsion layer

After the primitive emulsion 2 was chemically sensitized with gold and sulfur sensitizing agents, it was treated in the same way as the layer 2 of the specimen 1 and then applied.

Layers 3, 4, 5, 6, 7 and 8 were prepared in the same ways as the layers, 3, 4, 5, 6, 7 and 8 of the specimen 1 respectively, and then applied.

(Specimen 3)

The specimen 3 was prepared by sequentially applying the layers of the specimen 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 4 (green-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 2 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 4 of the specimen 1.

(Specimen 4)

The specimen 4 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1, except that the same emulsion as the layer 2 of the specimen 3 was applied as the layer 2 (red-sensitive emulsion layer), and the same emulsion as the layer 4 of the specimen 3 was applied as the layer 4 (green-sensitive emulsion layer).

(Specimen 5)

The specimen 5 was prepared by sequentially applying the layers of the specimen 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 7 (blue-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 2 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 7 of the specimen 1.

(Specimen 6)

The specimen 6 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1, except that the same emulsion as the layer 4 of the specimen 3 was applied as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 5 was applied as the layer 7 (blue-sensitive emulsion layer).

(Specimen 7)

The specimen 7 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1, except that the same emulsion as the layer 2 of the specimen 2 was applied as the layer 2 (red-sensitive emulsion layer), the same emulsion as the layer 4 of the specimen 3 was applies as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 5 was applied as the layer 7 (blue-sensitive emulsion layer).

(Specimen 8)

Layer 1: Antihalation layer (same as the layer 1 of specimen 1)

Layer 2: Red-sensitive silver halide emulsion layer

After the primitive emulsion 3 was chemically sensitized with gold and sulfur sensitizing agents, it was treated in the same way as the layer 2 of the specimen 1 and then applied.
Layers 3, 4, 5, 6, 7 and 8 were prepared in the same ways as the layers, 3, 4, 5, 6, 7 and 8 of the specimen 1 respectively, and then applied.

(Specimen 9)

The specimen 9 was prepared by sequentially applying the layers of the specimen 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 4 (green-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 3 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 4 of the specimen 1.

(Specimen 10)

The specimen 10 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 2 of the specimen 7 was applied as the layer 2 (red-sensitive emulsion layer), and the same emulsion as the layer 4 of the specimen 9 was applied as the layer 4 (green-sensitive emulsion layer).

(Specimen 11)

The specimen 11 was prepared by sequentially applying the layers of the specimen 8 on a cellulose triacetate support in the same way as the specimen 8, except that the layer 7 (blue-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 3 with gold and sulfur sensitizing agents and then treating it in the same manner as the specimen 1 in Example 1.

(Specimen 12)

The specimen 12 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 4 of the specimen 9 was applied as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 11 was applied as the layer 7 (blue-sensitive emulsion layer).

(Specimen 13)

The specimen 13 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 2 of the specimen 8 was applied as the layer 2 (red-sensitive emulsion layer), the same emulsion as the layer 4 of the specimen 9 was applies as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 11 was applied as the layer 7 (blue-sensitive emulsion layer).

(Specimen 14)

Layer 1: Antihalation layer (same as the layer 1 of specimen 1)
Layer 2: Red-sensitive silver halide emulsion layer After the primitive emulsion 4 was chemically sensitized with gold and sulfur sensitizing agents, it was treated in the same way as the layer 2 of the specimen 1 and then applied.
Layers 3, 4, 5, 6, 7 and 8 were prepared in the same ways as the layers 3, 4, 5, 6, 7 and 8 of the specimen 1 respectively, and then applied.

(Specimen 15)

The specimen 15 was prepared by sequentially applying the layers of the specimen 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 4 (green-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 4 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 4 of the specimen 1.

(Specimen 16)

The specimen 16 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 2 of the specimen 14 was applied as the layer 2 (red-sensitive emulsion layer), and the same emulsion as the layer 4 of the specimen 15 was applied as the layer 4 (green-sensitive emulsion layer).

(Specimen 17)

The specimen 17 was prepared by sequentially applying the layers of the specimen 1 in Example 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 7 (blue-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 4 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 7 of the specimen 1.

(Specimen 18)

The specimen 18 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 4 of the specimen 15 was applied as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 17 was applied as the layer 7 (blue-sensitive emulsion layer).

(Specimen 19)

The specimen 19 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 2 of the specimen 14 was applied as the layer 2 (red-sensitive emulsion layer), the same emulsion as the layer 4 of the specimen 15 was applied as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 17 was applied as the layer 7 (blue-sensitive emulsion layer).
The couplers, colored couplers and preparations of their dispersions used in Examples 1 and 2 were as described below.

Y-1:

α-[4-(1-Benzyl-2-phenyl-3,5-dioxo-1,2,4-triazo- lidinyl)]-α-pivalyl-2-chloro-5-[γ-(2,4-di-tert.-amylphenoxy)butylamido]acetanilide.

M-1:

1-(2,4,6-Trichlorophenyl)-3-[3-(2,4-di-tert.-amylphenoxyacetamido)benzoamido]-5-pyrazolone.

M-3:

4,4'-Methylenebis{1-(2,4,6-trichlorophenyl)-3-[3-(2,4-di-tert.-amylphenoxyacetamido)benzoamido]-5-pyrazolone}.

CM-1:

1-(2,4,6-Trichlorophenyl)-4-(l-naphthylazo)-3-(2-chloro-5-octadecenylsuccinimidoanilino)-5-pyrazolone.

C-1:

1-Hydroxy-4-[β-methoxyethylaminocarbonylmethoxy)-N-[6-(2,4-di-tert.-amylphenoxy)butyl]-2-naphthoamide.

CC-1:

1-Hydroxy-4-[4-(1-hydroxy-8-acetamido-3,6-disulfo-2-naphthylazo)phenoxy]-N-[6-(2,4-di-tert.-amylphenoxy) butyl]-2-naphthoamide disodium salt.

Dispersion (Y-l):

In 150 g. of dibutyl phthalate (DBP) and 500 mℓ. of ethyl acetate, 300 g. of the aforesaid yellow color forming coupler Y-1 was dissolved with heat. The solution thus obtained was added to 1600 mℓ. of 7.5% gelatin containing 18 g. of sodium triisopropylnaphthalene sulfonate. The mixture was then emulsified and dispersed in a colloid mill and adjusted to 2500 mℓ.

Dispersion (M-l):

In 77 g. of tri-cresyl phosphate and 280 mℓ. of ethyl acetate, 45 g. of the aforesaid magenta color forming coupler M-1, 18 g. of M-2 and 14 g. of CM-1 were dissolved with heat. The solution thus obtained was added to 500 mℓ. of a 7.5% aqueous gelatin solution containing 8 g. of sodium triisopropylnaphthalene sulfonate. The mixture was then emulsified and dispersed in a colloid mill and adjusted to 1000 mℓ.

Dispersion (C-l):

In a mixture of 55 g. of tri-cresyl phosphate (hereinafter referred to as TCP) and 110 mℓ. of ethyl acetate, 50 g of the aforesaid cyan color forming coupler C-1 and 4 g. of the colored cyan coupler CC-1 were dissolved with heat. The solution thus obtained was added to 400 mℓ. of a 7.5% aqueous gelatin solution containing 4 g. of sodium tri-isopropylnaphthalene sulfonate. The mixture was then emulsified and dispersed in a colloid mill and adjusted to 1000 mk.
These specimens were exposed to white light through a wedge and developed with a color processing liquid (CNK-4, available from Konishiroku Photo Industry Co., Ltd. in Japan). The photographic characteristics thus obtained were as shown in Table 1.
The effect of improvement in the image sharpness was evaluated by determining the modulation transfer function (MTF) and comparing the MTF values at a spatial frequency of 30 lines/mm. With respect to blue-sensitive emulsion layer, and 20 lines/mm. with respect to green- and red-sensitive layers.
As clearly shown in Table 1, specimens 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 15, 16, 17, 18 and 19 in accordance with the present invention showed the effects of remarkably improving the sharpness in comparison with specimens 1, 2, 8 and 14. Particularly, when the regular-crystal emulsion is used in the blue-sensitive emulsion layer which was the uppermost emulsion layer (specimens 5, 6, 7, 11, 12, 13, 17, 18 and 19), the sharpness was remarkably improved not only in this blue-sensitive layer but also in the green-sensitive emulsion layer which was positioned below said blue-sensitive emulsion layer. Further, even when the regular-crystal emulsion was used only in the green-sensitive emulsion layer, (specimens 3, 9 and 15), the quality of the image in this layer which governs the final image quality level was improved and, in addition, the sharpness in the red-sensitive emulsion layer was improved.
In case all layers were constituted by the regular-crystal silver halide grains (specimens 7, 13 and 19), the effect of improvement in the sharpness was most remarkable.
In Table 1, among those specimens in accordance with the present invention, the sharpness improving effect was larger when the octahedral or tetradecahedral crystals were used (specimens 9, 10, 11, 12, 13, 15, 16, 17, 18 and 19) as the regular crystal grains than when the cubic crystals (specimens 3, 4, 5, 6 and 7) were used.

Example 2

The primitive emulsion 5 and 6 were prepared as described below.

(Primitive emulsion 5)

An aqueous ammoniacal silver nitrate solution and an aqueous alkali halide solution were precipitated in an aqueous gelatin solution containing alkali halides at 40° C. over 83 minutes by maintaining the pAg value at 9.5 according to the pAg-controlled double jet mixing method. In this way, a silver iodobromide emulsion having an average crystal size of 0.65 p and a standard deviation of 0.16 µ and containing 5 mol % of essentially cubic silver iodide, with the content of twinned crystals being 8%, was obtained.

(Primitive emulsion 6)

An aqueous ammoniacal silver nitrate solution and an aqueous alkali halide solution were admixed with an aqueous gelatin solution containing alkali halides at 40° C. over 20 minutes by maintaining the pAg value at 10.0, and later 40 minutes the pAg value at 10.3 according to the pAg-controlled double jet mixing method. In this way, a silver iodobromide emulsion having an average crystal size of 0.65 µ and a standard deviation of 0.l49 µ and containing 5 mol % of essentially octahedral silver iodide, with the content of twinned crystals being 8%, was obtained.
Thereafter, the layers described below were coated on a support in the described order. The support was an under-coated cellulose triacetate film. In this way, specimens 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 and 31 were prepared.

(Specimen 20)

Layer 1: Antihalation layer (same as the layer 1 of specimen 1)
Layer 2: Red-sensitive silver halide emulsion layer After the primitive emulsion 5 was chemically sensitized with gold and sulfur sensitizing agents, it was treated in the same way as the layer 2 of the specimen 1 and then applied.
Layers 3, 4, 5, 6, 7 and 8 were prepared in the same ways as the layers 3, 4, 5, 6, 7 and 8 of the specimen 1 respectively, and then applied.

(Specimen 21)

The specimen 21 was prepared by sequentially applying the layers of the specimen 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 4 (green-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 5 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 4 of the specimen 1.

(Specimen 22)

The specimen 22 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 2 of the specimen 20 was applied as the layer 2 (red-sensitive emulsion layer), and the same emulsion as the layer 4 of the specimen 21 was applied as the layer 4 (green-sensitive emulsion layer).

(Specimen 23)

The specimen 23 was prepared by sequentially applying the layers of the specimen 1 in Example 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 7 (blue-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 5 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 7 of the specimen 1.

(Specimen 24)

The specimen 24 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 4 of the specimen 21 was applied as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 23 was applied as the layer 7 (blue-sensitive emulsion layer).

(Specimen 25)

The specimen 25 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 2 of the specimen 14 was applied as the layer 2 (red-sensitive emulsion layer), the same emulsion as the layer 4 of the specimen 20 was applies as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 23 was applied as the layer 7 (blue-sensitive emulsion layer).

(Specimen 26)

Layer 1: Antihalation layer (same as the layer 1 of specimen 1)
Layer 2: Red-sensitive silver halide emulsion layer After the primitive emulsion 6 was chemically sensitized with gold and sulfur sensitizing agents, it was treated in the same way as the layer 2 of the specimen 1 and then applied.
Layers 3, 4, 5, 6, 7 and 8 were prepared in the same ways as the layers 3, 4, 5, 6, 7 and 8 of the specimen 1 respectively, and then applied.

(Speciment 27)

The specimen 27 was prepared by sequentially applying the layers of the specimen 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 3 (green-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 6 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 3 of the specimen 1.

(Specimen 28)

The specimen 28 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 2 of the specimen 26 was applied as the layer 2 (red-sensitive emulsion layer), and the same emulsion as the layer 4 of the specimen 27 was applied as the layer 4 (green-sensitive emulsion layer).

(Specimen 29)

The specimen 29 was prepared by sequentially applying the layers of the specimen 1 in Example 1 on a cellulose triacetate support in the same way as the specimen 1, except that the layer 7 (blue-sensitive emulsion layer) was prepared by sensitizing the primitive emulsion 6 with gold and sulfur sensitizing agents and then treating it in the same manner as the layer 7 of the specimen 1.

(Specimen 30)

The specimen 30 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 4 of the specimen 27 was applied as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 29 was applied as the layer 7 (blue-sensitive emulsion layer).

(Specimen 31)

The specimen 31 was prepared by sequentially applying the layers on a cellulose triacetate support in the same way as the specimen 1 in Example 1, except that the same emulsion as the layer 2 of the specimen 26 was applied as the layer 2 (red-sensitive emulsion layer), the same emulsion as the layer 4 of the specimen 27 was applied as the layer 4 (green-sensitive emulsion layer), and the same emulsion as the layer 7 of the specimen 29 was applied as the layer 7 (blue-sensitive emulsion layer).
Development was conducted in the same manner as in Example 1, and the image sharpness was evaluated. The results were as shown in Table 2.
A comparison between Examples 1 and 2 clearly shows that with respect to the specimens in which the silver halide grains having the same crystal habit are used as in specimens between 3, 4, 5, 6, 7 and 21, 22, 23, 24, 25 (cubic crystals), and in specimens between 9, 10, 11, 12, 13 and 27, 28, 29, 30, 31 (octahedral crystals), the effect on the sharpness increases as the content of the twinned crystals decreases.

Claims

1. A silver halide light-sensitive color photographic material comprising a blue-sensitive, a green-sensitive, and a red-sensitive negative type light-sensitive silver halide emulsion layers provided on a support, at least 80% of the silver halide grains contained in the light-sensitive silver halide emulsion layer farthest from said support or in the green-sensitive silver halide emulsion layer being constituted by regular-crystal silver halide grains.

2. A silver halide light-sensitive color photographic material according to Claim 1 wherein said regular-crystal silver halide grains are tetradecahedral crystals and/or octahedral crystals.

3. A silver halide light-sensitive color photographic material according to Claim 1, 2 or 3 wherein said light-sensitive silver halide emulsion layers contain a compound which forms a dye by reacting with an oxidized product of an aromatic primary amine developing agent.

4. A silver halide light-sensitive color photographic material according to Claim 1 or 2,wherein at least 80% of the silver halide grains contained in all light-sensitive emulsion layers are constituted by regular-crystal silver halide grains.

5. A silver halide light-sensitive color photographic material according to Claim 3, wherein at least 80% of the silver halide grains contained in all light-sensitive emulsion layers are constituted by regular-crystal silver halide grains.

6. A silver halide light-sensitive color photographic material according to Claim 1 or 2,wherein 90% or more of the silver halide grains contained in the light-sensitive silver halide emulsion layers are constituted by regular-crystal silver halide grains.

7. A silver halide light-sensitive color photographic material according to Claim 3 wherein 90% or more of the silver halide grains contained in the light-sensitive silver halide emulsion layers are constituted by regular-crystal silver halide grains.

8. A silver halide light-sensitive color photographic material according to Claim 4 wherein 90% or more of the silver halide grains contained in the light-sensitive silver halide emulsion layers are constituted by regular-crystal silver halide grains.

9. A silver halide light-sensitive color photographic material according to Claim 5 wherein 90% or more of the silver halide grains contained in the light-sensitive silver halide emulsion layers are constituted by regular-crystal silver halide grains.