GB2180359A - Silver halide color reversal photographic materials - Google Patents

Abstract

Color reversal photographic material comprises a plurality of silver halide photographic emulsion layers, at least two of which have substantially the same color sensitivity in the visible spectrum, and of such layers of the same color sensitivity: in one layer (a) the AgX grains which provide at least 50% of the total projected area of all the grains in that layer are tabular AgX grains having an average aspect ratio, i.e. ratio of grain equivalent diameter to thickness, of 5:1 or more, and preferably are internal latent image forming, and another layer (b) has a lower degree of sensitivity than that of layer (a) and contains AgX (e.g. AgBrl) grains each comprising a core and a shell, and at least the surface of each core has been chemically sensitized; the molar ratio of core:shell Ag ion is preferably 1:19 to 99:1, more preferably 1:1 to 19:1 and the equivalent diameter of the core shell grains is 5,0 mu m or less, preferably >3 mu . The material has high sharpness, good graininess and high sensitivity; and can form a color positive image of improved gradation and well stabilized gradation balance by color reversal treatment.

Description

SPECIFICATION Silver halide color reversal photographic materials The present invention relates to silver halide color reversal photographic materials wherein at least one silver halide emulsion layer contains tabular silver halide grains. The magerials have high image sharpness and high sensitivity with reduced variation of gradation in high speed development.

Silver halide color photographic materials for camera use are required, irrespective of negative films or reversal films, to have high image quality, high sensitivity and high treatment stability.

Regarding the image quality, the important factors are sharpness, graininess and color reproductivity; and regarding the treatment stability, it is important that the gradation balance is correctly maintained during the standard treatment of the color reversal photographic materials as well as in the sensitization treatment thereof.

In the use of conventional multilayer color photographic materials comprising, on a support, blue-sensitive, green-sensitive and red-sensitive silver halide emulsion layers, it is known that light scattering due to the silver halide grains is apt to result in the deterioration of the sharpness of the emulsion layers positioned as the inner layers.

British Patent No. 2,112,157 A (corresponding to U.S. Patent 4,439,520) describes silver halide photographic materials, usually with red, green and blue color-forming layers, wherein at least one such layer contains chemically and spectrally sensitized tabular silver halide grains having a thickness of less than 0.5 nm, a diameter (calculated as that of the circle of equivalent area) of at least 0.6 nm and an average aspect ratio (ratio of grain diameter to thickness) of greater than 8:1, preferably at least 12:1 or 20:1, these tabular grains constitute at least 50% of the total projected area of the grains in that layer. There can be faster and slower emulsion layers in each color-forming unit, in which case it is preferred that the faster emulsion layer should contain the tabular grains (see page 26).Tabular grains have two parallel or substantially parallel crystal faces each of which is substantially larger than any other single face of the grain.

The materials of British Patent No. 2,112,157 A have improved sharpness, sensitivity and graininess. However, the materials do not behave well in color reversal development, which is a photographic process for the formation of color positive images, wherein negative type silver halides are first subjected to black-and-white development (first development) and then the remaining silver halides are thereafter fogged for color development to obtain color positive images. The black-and-white developer to be used in the first development contains a silver halide solvent such as potassium thiocyanate or sodium sulfite, which may accelerate the development of silver halides by solution physical development.However, when silver halide grains whereof mainly their surfaces are photosensitized are used, the developer is apt to cause the loss or deterioration of the sensitivity of the grains due to the surface dissolution of the photosensitized grains. In addition, the developer often causes an increase of the apparent sensitivity of the positive color images because of the dissolution of other unexposed grains, and thus the variation of the sensitivity especially causes a severe variation of the gradaiton in high speed development.

Recently, color photographic materials for camera use of high sensitivity, including reversal photographic materials, generally comprise several silver halide emulsion layers each having blue sensitivity, green sensitivity and red sensitivity and having a different degree of sensitivity. In the photographic treatment of such color photographic materials, it has been found that the dissolution of the silver halides by the black-and-white developer used depends upon the shapes of the silver halide grains in the emulsions used jointly in each of the high-sensitive, middle-sensitive and low-sensitive layers.More precisely, the incorporation of tabular silver halide grains into high-sensitive and/or middle-sensitive layers results in the formation of silver halide color reversal photographic materials of improved sharpness, while the high solution physical activity of the tabular grains excessively accelerates the dissolution of other silver halides in the adjacent emulsion layers, resulting in harmful influences on the photographic materials, for example, loss or deterioration of the sensitivity of the finally obtained color positive images and occurrence of the variation of the gradation of the images and the variation of the gradation balance thereof.

Such defects are especially emphasized when the emulsions adjacent to the tabular graincontaining emulsion layers comprise small grains, and therefore, some adequate remedy for the solution of these defects are required. In particular, the final quality is determined depending upon a delicate color balance of the color images formed in the color reversal photographic materials, and, therefore, these defects have a serious effect on the quality of the materials.

An object of the present invention is to overcome the defects of the prior art and to provide silver halide color reversal photographic materials of high sharpness, good graininess and high sensitivity.

Another object of the present invention is to provide silver halide color reversal photographic materials which may form color positive images of improved gradation and well stabilized gradation balance by reversal treatment of the negative type silver halide emulsion layer units.

Still another object of the present invention is to provide silver halide color reversal photographic materials capable of forming color images of good gradation by high speed development.

A further object of the present invention is to provide a method for the formation of color positive images of high sharpness, good graininess, high sensitivity and high treatment stability.

We have now found that in materials of the aforesaid type of British Patent 2,112,157 A having at least two layers of higher and lower sensitivity in the same color-forming unit (e.g., blue, green or red color-sensitive), it is advantageous if the layer of the lower sensitivity contains grains having a core/shell structure whereof at least the core is chemically sensitized, and thus the foregoing objects can be attained.

According to the present invention we provide a color reversal photographic material which comprises, on a support, a plurality of silver halide photographic emulsion layers, at least two of which have substantially the same color sensitivity in the visible spectrum, and of such layers of the same color sensitivity: in one layer (a) the silver halide grains which provide at least 50% of the total projected area of all the silver halide grains in that layer are tabular silver halide grains having an average aspect ratio, namely the ratio of grain equivalent diameter to thickness, of 5:1 or more, and another layer (b) has a lower degree of sensitivity than that of layer (a) and contains silver halide grains each comprising a core and a shell, and at least the surface of the core has been chemically sensitized.

Tabular Silver Halide Emulsions (a) The tabular silver halide-containing emulsions and the emulsions containing internally sensitized silver halide grains which are used in the present invention are preferably negative type emulsions.

The diameter of the tabular silver halide grains is 5.0 ,am or less, preferably 0.5 to 3.0 ,am, calculated in terms of the corresponding spheres. The thickness thereof is 0.4 m or less, preferably 0.3 to 0.05 Hm, more preferably 0.02 to 0.05 Am.

The tabular silver halide grains usually have two parallel surfaces and, therefore, the thickness of the grains is represented by the distance between the two parallel surfaces of the tabular silver halide grains.

The aspect ratio of the tabular grains, i.e., the ratio of grain diameter to thickness, is 5:1 or more, preferably 5-30:1, more preferably 5-8:1.

The proportion of the tabular silver halide grains contained in the tabular silver halide-containing emulsion, which is used in the photographic materials of the present invention, is 50% or more of the total projected area of all silver halide grains contained in the emulsion, preferably 70% or more thereof, more preferably 90% or more thereof.

The tabular silver halide grains in the present invention may be used in the form of a monodispersed system with respect to the dispersion state of the grain diameter and/or thickness of the silver halide grains as described, for example, in Japanese Patent Publication No. 11386/72.

The term' "monodispersed system of the tabular silver halide grains" means herein that the silver halide emulsion comprises such dispersion system that 95% of the total silver halide grains have a particle size falling within the scope of the number average grain size +60% or less, preferably +40% or less. The term "number average grain size" means the number average diameter of the projected area diameter of the silver halide grains.

The halogen composition of the tabular silver halide grains is preferably silver bromide, silver iodobromide, silver chlorobromide, silver chloroiodobromide, silver chloride or silver iodochloride.

When such emulsion is used for the formation of photographic materials of high sensitivity, silver iodobromide, silver bromide, silver chlorobromoiodide or a mixture thereof is especially preferred. In the case of silver iodobromide, the content of silver iodide is generally 40 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less. The tabular grains may have a uniform halogen composition or may comprise two or more phases having different halogen compositions.

If tabular silver bromoiodide grains are used, these grains may comprise those of a multilayer constitution of several phases, each composed of a different iodide content. Japanese Patent Applications (OPI) Nos. 113927/83, 113928/83, 99433/84, 119344/84 and 119350/84 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") describe some preferred examples of halogen compositions of the tabular silver halide grains and the halogen distribution in the grains.

The tabular grains may be selected from those having a face of (111), (100) or a mixture of (111) and (100).

Regarding the site for the formation of latent images in the silver halide grains, the latent image may be formed mainly on the surfaces of the grains, or may be formed mainly internally of the grains. In addition, the latent image may be formed both on the surfaces and internally. In the present invention, silver halide grains which may form latent images internally are preferably used.

The method for the formation of the tabular silver halide grains will now be described. Various conventional means which are well known in this technical field may be used and may be appropriately combined.

For instance, seed crystals containing 40% by weight or more of tabular grains are first formed in an atmosphere of a relatively low pBr value, e.g., pBr of 1.3 or less, and then silver and a halogen solution are simultaneously added thereto so as to grow the seed crystals while the pBr value in the atmosphere is kept at the same value to obtain the desired tabular silver halide grains. During the process of growing the grains, it is preferred that the silver and halogen solution are so added that no new crystal nuclei are formed.

The size of the tabular silver halide grains may be regulated by suitably controlling the temperature, the kind and the amount of the solvents to be used and the addition speed of the silver salts and halides added during the growth of the grains.

In the formation of the tabular silver halide grains, silver halide solvents, e.g., ammonia, thioethers or thioureas, may optionally be used, if necessary, whereby the size of the grains, the shape of the grains (e.g., ratio of diameter/thickness), the grain size distribution and the speed of growth of the grains may suitably be controlled. The amount of the solvent used is preferably 10-3 to 1.0 wt%, especially preferably 10-2 to 10-' wt%. The grain size distribution of the tabular silver halide grains may be shifted to a mono-dispersed system and the speed of growth of the grains may be accelerated, with the increase of the amount of the solvent used. On the other hand, the thickness of the grains increases in some cases, with increase of the amount of the solvent.

Silver halide solvents are, therefore, added in the manufacture of the tabular silver halide grains of the present invention for the purpose of acceleration of the growth of the grains. For this purpose, methods for the acceleration of the addition speed of the silver salt solution (such as AgNO3 aqueous solution) and the halide solution (such as KBr aqueous solution), methods for the enlargement of the amount of the solutions, and methods for the increase of the concentration of the solutions when added are preferably utilized in the manufacture of the tabular silver halide grains of the present invention.

The tabular silver halide grains and silver halide emulsions containing the grains, as well as the manufacture of these grains and emulsions, are described in greater detail, for example, in U.S.

Patents 4,434,226, 4,439,520, 4,414,310, 4,425,425, 4,399,215, 4,435,501, 4,386,156, 4,400,463, 4,414,306 and 4,425,426, European Patent 84637 A2, Japanese Patent Application (OPI) No. 99433/84, and Research Disclosure, No. 22534 (January, 1983).

The thickness of the layer containing the tabular silver halide grains is preferably 0.3 to 6.0 m, more preferably 0.5 to 4.0 Am The amount of the tabular silver halide grains coated on a support is preferably 0.1 g/m2 to 6 g/m2, more preferably 0.3 g/m2 to 3 g/m2.

Internally Sensitized Core/Shell Silver Halide Grains The internally sensitized silver halide grains used in the layers (b) each comprises a core covered by a shell, and at least the surface of the core is chemically sensitized. The diameter of the grains is 5.0 m or less, preferably 3 ,um or less, as calculated in terms of the corresponding spherical grains.

The molar ratio of the Ag+ ion used to form the core and the shell of the grains is preferably 1:19 to 99:1 (core : shell), more preferably 1:1 to 19:1.

The halogen composition in the core and the shell of the grains may generally be selected from silver bromide, silver iodobromide, silver chlorobromide, silver chloroiodobromide, silver chloride and silver iodochloride, and silver iodobromide is preferred. The content of silver iodide in the silver iodobromide is generally 40 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less. The halogen composition of the core and that of the shell may be the same or different from each other.

The internally sensitized silver halide grains may be tabular grains having an aspect ratio of 5 or more, as described hereinabove, or may be any other conventional silver halide grains, or may be a mixture of these grains. Conventional silver halide grains which may thus be used include regular grains having cubic, octahedral, tetradecahedral, diamond-shaped dodecahedral or the like regular crystalline forms; and polydispersed or monodispersed grains having spherical, potato-shaped or other irregular crystalline forms.

Internal latent image-forming emulsions comprising tabular, octahedral, cubic, spherical or tetradecahedral grains are preferably used in the present invention. The crystal habit and the shape of the core and the shell of the grains may be the same or different from each other.

The surface of the shell may also be chemically sensitized, if desired.

The internally chemically sensitized silver halide grains may be obtained by means of a method (i) where the cores are chemically sensitized and then a silver ion and a halogen ion are added thereto for filtration, or (ii) where the cores are chemically sensitized and then fine grains which have apparently smaller size than the core grains are added thereto and thereafter the whole is subjected to Ostwald ripening. Such silver halide grains as well as the manufacture thereof are described in detail, for example, in U.S. Patents 3,206,313, 3,317,322, 3,917,485 and 3,979,213.

Other Silver Halide Emulsion Layers The photographic emulsion layers other than the silver halide emulsion layers (a) and (b) defined above in the photographic materials of the present invention may contain any silver halides selected from silver bromide, silver iodobromide, silver chlorobromide, silver chloroiodobromide, silver chloride and silver chloroiodide, and silver iodobromide is preferred for photographic materials of high sensitivity. In the case of silver iodobromide, the content of silver iodide is generally 40 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less.

Silver halide grains may be any of so-called regular grains having cubic octahedral, tetradecahedral or the like regular crystalline forms; grains having spherical or other irregular crystalline forms; grains having twin planes or other crystal defects; or grains comprising the composite forms of these crystalline forms.

Silver halide grains may be fine grains having a grain diameter of about 0.1 Am or less or may be large grains having a large grain size of up to about 10 ijm (diameter of projected area); and these may form a mono-dispersed system emulsion having a narrow grain size distribution or a polydispersed system emulsion having a broad grain size distribution.

Emulsion layers may contain tabular grains having an aspect ratio of 5 or more.

The grains in the emulsions described above may have a uniform crystal constitution, or may comprise different inner and outer halogen compositions or may have a layer constitution. These emulsion grains are described, for example, in BritishsPatent 1,027,146, U.S. Patents 3,505,068 and 4,444,877 and Japanese Patent Application (OPI) No. 143331/85. In addition, silver halide grains may be epitaxial grains comprising different halogen compositions jointed by an epitaxial junction, or as the case may be, these may contain any other compounds than silver halides, such as silver rhodanide or lead oxide, jointed therewith. These emulsion grains are described, for example, in U.S. Patents 4,094,684, 4,142,900 and 4,459,353, British Patent 2,038,792, U.S.Patents 4,349,622, 4,395,478, 4,433,501, 4,463,087, 3,656,962 and 3,852,067, and Japanese Patent Application (OPI) No. 162540/84.

The silver halide photographic emulsions of the present invention may be any of a surface latent image type emulsion which may form a latent image mainly on the surfaces of grains, an internal latent image type emulsion which may form a latent inmage mainly in the internal parts of the grains or a composite type emulsion which may form a latent image both on the surfaces and in the internal parts of the grains.

The silver halide photographic emulsions which may be used jointly in the present invention may be prepared in a conventional manner. For instance, the methods described in Research Disclosure, Vol. 176, No. 17643 (December, 1978), pp. 22-23, "I. Emulsion Preparation and Types" and Research Disclosure, Vol. 187, No. 18716 (November, 1979), p. 648 may be adapted to the present invention.

Further, the photographic emulsions to be used jointly in the present invention may be obtained in a conventional manner, for example, as described in P. Glafkides, Chimie et Physique Photographique (Paul Montel, 1967), G.F. Duffin, Photographic Emulsion Chemistry (Focal Press, 1966) and V.L. Zelikman et al., Making and Coating Photographic Emulsion (Focal Press, 1964).

For instance, any of an acid method, a neutral method or an ammonia method may be adapted to the formation of the emulsions; and to the reaction of a soluble silver salt and a soluble halogen salt, a single jet method, a double jet method or a combination thereof may be adopted.

In addition, a method for the formation of silver halide grains in the presence of excess silver ions (which is a so-called reverse jet method) may also be utilized. A so-called controlled double jet method where the pAg value in the liquid phase for the formation of silver halides is maintained at a constant level may also be used, which is one embodiment of the double jet method. According to this method, an emulsion of silver halide grains having regular crystalline forms and having a nearly uniform grain size may be obtained.

In the preparation of the photographic emulsions to be used jointly in the present invention, various kinds of silver halide solvents may optionally be used, if necessary, including, for example, ammonia or Rhodankali or thioethers and thione compounds as described, for example, in U.S. Patent 3,271,157 and Japanese Patent Applications (OPI) Nos. 12360/76, 82408/78, 144319/78, 100717/79 and 155828/79.

Emulsions of silver halides of regular grains to be used jointly in the present invention may be obtained by properly controlling the pAg value and the pH value during the formation of the grains. The detail is described, for example, in Photographic Science and Engineering, Vol, 6, pp.

159-165 (1962), Journal of Photographic Science, Vol. 12, pp. 242-251 (1964), and U.S.

Patent 3,655,394 and British Patent 1,413,748.

Typical monodispersed emulsions are those comprising silver halide grains having a larger average grain diameter than about 0.1 Am, at least 95 wt% of the grains having a grain size which falls within the scope of the average grain diameter +40%. In particular, emulsions containing silver halide grains which have an average grain diameter of 0,25 to 2 Fm, at least 95 wt% (or at least 95% of the total number of grains) having a grain size which falls within the scope of the average grain diameter +20%, are preferably used in the present invention. The manufacture of these emulsions is described, for example, in U.S. Patents 3,574,628 and 3,655,394 and British Patent 1,413,748.In addition, monodispersed emulsions as described in Japanese Patent Applications (OPI) Nos. 8600/73, 39027/76, 83097/76, 137133/78, 48521/79, 99419/79, 37635/83 and 49938/83 may further preferably be used in the present invention.

In the formation of silver halide grains or in the physical ripening step thereof, a cadmium salt, a zinc salt, a lead salt, a thallium salt, an iridium salt or a complex salt thereof, a rhodium salt or a complex salt thereof or an iron salt or a complex salt thereof may be incorporated in the reaction system.

The removal of soluble silver salts from the emulsions before or after the physical ripening thereof may be carried out by noodle washing, flocculation sedimentation or ultrafiltration.

The emulsions used in the present invention are generally those which have been chemically ripened and/or spectrally sensitized after physical ripening. Additives which may be used in the steps of physical ripening, chemical ripening and spectral sensitization are described in the aforesaid Research Disclousre, No. 17643 (December, 1978) and No. 18716 (November, 1979), and the relevant disclosures in these publications are listed under items 1 and 3 in the following Table 1.

TABLE 1 No. Kind of Additives RD 17643 RD 18716 1 Chemical sensitizer p. 23 p. 648, right column 2 Sensitivity enhancement ditto 3 Spectral sensitizer and pp. 23-24 from p. 648, right Supersensitizer column to p. 649, right column 4 Brightener p. 24 5 Antifogging agent and pp. 24-25 p. 649, right column stabilizer 6 Light absorbent, Filter pp. 25-26 from p. 649, right dye and UV absorbent column to p. 650, left column 7 Stain inhibitor p. 25, p. 650, left to right column right column 8 Color image stabilizer p. 25 9 Hardener p. 26 p. 651, left column 10 Binder p. 26 ditto 11 Plasticizer and p. 27 p. 650, right column Lubricant 12 Coating assistant agent pp. 26-27 ditto and Surfactant 13 Antistatic agent p. 27 ditto In multicolor material, the emulsion layers have the same color sensitivity in the same bluesensitive, green-sensitive or red-sensitive emulsions, as is customary in conventional multilayer silver halide color photographic materials; this means that the emulsions of "substantially the same color sensitivity" have a common sensitivity in the main range of a visible spectrum. In general, the photographic materials of the present invention have two or three emulsion layers having the same color sensitivity but each having a different degree of sensitivity.

Couplers To obtain the required color sensitivity (usually to blue, green or red light), various kinds of color couplers may be used in the present invention, and specific examples thereof are described in patent specification referred to in the aforesaid Research Disclosure, No. 17643, VII-C to G.

Important dye-forming couplers are those capable of forming three primary colors (or yellow, magenta and cyan) in a subtractive color process by color development, and examples of nondiffusible and hydrophobic 4-equivalent or 2-equivalent couplers which may be used in the present invention are described in the patent specifications referred to in Research Disclosure, No. 17643, VII-C and D. In addition, other couplers as mentioned below may also preferably be used in the present invention.

Typical examples of yellow couplers which may be used in the present invention are hydro phobic acylacetamide type couplers having a ballast group. Specific examples thereof are described in U.S. Patents 2,407,210, 2,875,057 and 3,265,506. 2-Equivalent yellow couplers are particularly preferably used in the present invention; and typical examples thereof are oxygen atom-eliminating type yellow couplers as described in U.S. Patents 3,408,194, 3,447,928, 3,933,501 and 4,022,620; and nitrogen atom-eliminating type yellow couplers as described in Japanese Patent Publication No. 10739/83, U.S.Patents 4,401,752 and 4,326,024, Research Disclosure, No. 18053 (April, 1979), British Patent 1,425,020, German Patent Application (OLS) Nos. 2,219,917, 2,261,361, 2,329,587 and 2,433,812. a-Pivaloylacetanilide type couplers are good in fastness, especially to light, of the dyes formed; and on the other hand, a-benzoylacetanilide type couplers are good in the high color density of the dyes formed.

Magenta couplers which may be used in the present invention are ballast group-containing hydrophobic indazolone type or cyanoacetyl type couplers, preferably 5-pyrazolone type or pyrazoloazole type couplers. Among the 5-pyrazolone type couplers, those whose 3-position is substituted by an arylamino group or an acylamino group are preferred because of the hue and the color density of the dyes formed. Typical examples of such couplers are described in U.S.

Patents 2,311,082, 2,343,703, 2,600,788, 2,908,573, 3,062,653, 3,152,896 and 3,936,015.

Regarding the eliminating groups of the 2-equivalent 5-pyrazolone type couplers, nitrogen atomeliminating groups as described in U.S. Patent 4,310,619 and arylthio groups as described in U.S. Patent 4,351,897 are especially preferred. In addition, ballast group-containing 5-pyrazolone type couplers as described in European Patent 73,636 are preferred as forming color images of high color density. Pyrazoloazole type couplers which may be used in the present invention include pyrazolobenzimidazoles as described in U.S. Patent 3,061,432, preferably pyrazolo[5,1 c ] {1 ,2,4j-triazoles as described in U.S Patent 3,725,067, pyrazolotetrazoles as described in Research Disclousre, No. 24220 (June, 1984) and Japanese Patent Application (OPI) No.

33552/85 and pyrazolopyrazoles as described in Research Disclosure, No. 24230 (June, 1984) and Japanese Patent Application (OPI) No. 43659/85. In particular, imidazo [ 1,2-b ] pyrazoles as described in U.S. Patent 4,500,630 are preferred because the mellow by-absorption of the dyes formed is small and the light fastness thereof is high, and especially, pyrazolo [ 1,5-b ] [ 1,2,4 ] - triazoles as described in European Patent 119,860 A are particularly preferred.

Cyan couplers which may be used in the present invention are hydrophobic and nondiffusible naphthol type and phenol type couplers; and typical examples thereof are naphthol type couplers as described in U.S. Patent 2,474,293, preferably oxygen atom-eliminating type 2-equivalent naphthol couplers as described in U.S. Patents 4,052,212, 4,146,396, 4,228,233 and 4,296,200. Specific examples of phenol type couplers are described, for example, in U.S.

Patents 2,369,929, 2,801,171, 2,772,162 and 2,895,826.

Cyan couplers which are fast to moisture and temperature are preferably used in the present invention, and typical examples thereof are phenol type cyan couplers having a higher alkyl group than ethyl group in the meta-position of the phenol nucleus, as described in U.S. Patent 3,772,002; 2,5-diacylamino-substituted phenol type couplers as described in U.S. Patents 2,772,162, 3,758,308, 4,126,396, 4,334,011 and 4,327,173, German Patent Application (OLS) No. 3,329,729 and European Patent 121,365; and phenol type couplers having a phenylureido group in 2-position and an acylamino group in 5-position, as described in U.S. Patents 3,446,622, 4,333,999, 4,451,559 and 4,427,767.

In order to compensate for any unnecessary absorption of the color dyes formed, color negative films for camera use preferably contain a colored coupler for masking. Typical examples of the colored couplers are yellow colored magenta couplers as described in U.S. Patent 4,163,670 and Japanese Patent Publication No. 39413/82; and magenta colored cyan couplers as described in U.S. Patents 4,004,929 and 4,138,258 and British Patent 1,146,368. Other colored couplers are described in the aforesaid Research Disclosure No. 17643, VII-G.

Couplers which may form colored dyes of pertinent diffusibility may also be co-used together with the aforesaid couplers for the purpose of improving the graininess of the photographic materials. Regarding such couplers, examples of magenta couplers are described in U.S. Patent 4,366,237 and British Patent 2,125,570 and those of yellow, magenta and cyan couplers are described in European Patent 96,570 and German Patent Application (OLS) No. 3,234,533.

The dye-forming couplers and the other special couplers as described above may form dimers or polymers. Typical examples of polymerized dye-forming couplers are described in U.S. Patents 3,451,820 and 4,080,211. Examples of polymerized magenta couplers are described in British Patent 2,102,173 and U.S. Patent 4,367,282.

Couplers which may release a photographically useful group in coupling may also preferably be used in the present invention. DIR couplers capable of releasing a development inhibitor are described in patent specifications as referred to in the aforesaid Research Disclosure, No. 17643, VII-F, which may advantageously be used in the present invention.

DIR couplers which may preferably be used in the present invention are developer-deactivating type couplers as typically described in Japanese Patent Application (OPI) No. 151944/82; timing type couplers as typically described in U.S. Patent 4,248,962 and Japanese Patent Application (OPI) No. 154234/82; and reactive type couplers as typically described in Japanese Patent Application (OPI) No. 184248/85. In particular, especially preferred couplers are developerdeactivating type DIR couplers as described in Japanese Patent Application (OPI) Nos.

151944/82, 217932/83, 218644/85, 225156/85 and 233650/85; and reactive type DIR couplers as described in Japanese Patent Application (OPI) No. 184248/85.

The couplers may be incorporated into the photographic materials of the present invention by means of various known dispersion methods, and, for instance, typical methods are a solid dispersion method, an alkali dispersion method, preferably a latex dispersion method, more preferably an oil-in-water dispersion method. According to the oil-in-water dispersion method, a coupler is first dissolved in either a high boiling point organic solvent having a boiling point of 1750C or higher or a so-called auxiliary solvent having a low boiling point or in a mixture of these two solvents, and then the resulting solution is finely dispersed in water or in an aqueous medium such as a gelatin aqueous solution in the presence of a surfactant. Examples of the high boiling point organic solvents are described, for example, in U.S. Patent 2,322,027.The dispersion may be accompanied by phase inversion. If necessary, the auxiliary solvent as used in the dispersion may be removed or reduced by distillation, noodle washing or ultrafiltration, and then the coupler-containing dispersion is coated on a support.

The process and the effect of the latex dispersion method and specific examples of latexes to be used for the immersion in the method are described, for example, in U.S. Patent 4,199,363 and German Patent Application (OLS) Nos. 2,541,274 and 2,541,230.

Other Additives Conventional photographic additives may be used in the photographic materials of the present invention, which are also described in the aforesaid two publications of Research Disclosure, and the relevant disclosures therein are also listed in the Table 1 above.

The photographic materials may contain a color fogging inhibitor or a color stain inhibitor, for example, selected from hydroquinone derivatives, amiophenol derivatives, amines, gallic acid derivatives, catechol derivatives, ascorbic acid derivatives, colorless couplers and sulfonamidophenol derivatives.

The photographic materials of the present invention may further contain various kinds of discoloration inhibitors. Typical examples of organic discoloration inhibitors are hindered phenols such as hydroquinones, 6-hydroxychromans, 5-hydroxycoumarans, spirochromans, p-alkoxyphenols and bisphenols; and gallic acid derivatives methylenedioxybenzenes, aminophenols and hindered amines and ether or ester derivatives of the compounds in which the phenolic hydroxyl group is silylated or alkylated. In addition, metal complexes such as (bissalicylaldoximato)nickel complex and (bis-N,N-dialkyldithiocarbamato)nickei complex may also be used.

Layer Structure The material of the invention may be multilayer and multicolor photographic material having at least two layers each having a different spectral sensitization on a support. Multilayer natural color photographic materials generally have at least one red-sensitive emulsion layer, at least one green-sensitive emulsion layer and at least one blue-sensitive emulsion layer on a support. The arrangement of these layers on a support may freely be selected, depending upon the use of the photographic materials. In particular, a preferred layer arrangement is red-sensitive layer/greensensitive layer/blue-sensitive layer in this order from the support; or blue-sensitive layer/redsensitive layer/green-sensitive layer in this order from the support.Each of the emulsion layers may comprise two or more emulsion layers each having a different sensitivity; or a nonphotosensitive layer may be provided between or among two or more emulsion layers each having the same sensitivity. It is usual for a cyan-forming coupler to be incorporated in a redsensitive emulsion layer, a magenta-forming coupler in a green-sensitive emulsion layer and a yellow-forming coupler in a blue-ensitive emulsion layer; and such combinations may be modified to different combinations, if necessary.

The photographic materials of the present invention preferably contain, in addition to the above-described silver halide emulsion layers, auxiliary layers suitably provided on a support such as a protective layer, an intermediate layer, a filter layer, an antihalation layer, a backing layer or other auxiliary layers.

In the photographic materials of the present invention, the aforesaid photographic emulsion layers and other layers are appropriately coated on a support which is generally used for photographic light-sensitive materials, for example, a flexible support such as plastic films, papers or cloths or a rigid support such as glasses, ceramics or metals. Especially usable flexible supports are films made of cellulose derivatives (such as cellulose nitrate, cellulose acetate or cellulose acetate-butyrate) or synthetic high molecular substances (such as polystyrene, polyvinyl chloride, polyethylene terephthalate or polycarbonate); and papers coated or laminated with a baryta layer or an a-olefin polymer (such as polethylene, polypropylene, ethylene/butene copolymer). These supports may be colored with dyes or pigments. If desired, these may be blackened for the purpose of light shielding.The surface of these supports is in general subbed with a subbing layer for the purpose of improving the adhesiveness of photographic emulsion layers. In addition, the surface of the supports may be subjected to glow discharge treatment, corona discharge treatment ultraviolet ray irradiation of flaming treatment, before or after the subbing treatment.

In coating the photographic emulsion layers and other hydrophilic colloid layers on a support, various known coating methods may be utilized, such as a dip coating method, a roller coating method, a curtain coating method or an extrusion coating method. A plurality of layers may simultaneously be coated on a support by means of the coating method as described in U.S.

Patents 2,681,294, 2,761,791, 3,526,528 and 3,508,947.

Development The color photographic materials of the present invention may be developed by means of a conventional developing means as described, for example, in the aforesaid Research Disclosure, No. 17643, pp. 28-29 and No. 18716 p. 651, from left-hand column to right-hand column. The first developer of the reversal development is a black-and-white developer containing a silver halide solvent. In the case where the silver halide grains are sensitized with such a first developer, the time for the sensitization treatment is possibly elongated longer than that in a normal treatment by at most 3 times. In this treatment, if the temperature during the treatment is elevated, the elongated period of time for the sensitization treatment may be reduced.The color photographic material of the present invention are in general subjected to a treatment of washing with water or a treatment of stabilization after the development and bleaching-fixation or fixation of the materials.

In the washing step with water, a counter-current washing by the use of two or more water tanks is general for the purpose of econony of the amount of water used. A stabilization treatment may be carried out in place of washing with water, and a typical embodiment of the stabilization treatment is a multistage counter-current stabilization treatment as described in Japanese Patent Application (OPI) No. 8543/82. In the process of the stabilization treatment, two to nine countercurrent baths are required.

Various kinds of compounds are added to the baths in the stabilization step for the purpose of stabilizing the images formed. For instance, typical additives are various kinds of buffers to adjust the film pH (e.g., to the range of pH 3 to 8) such as borates, metaborates, borax, phosphates, carbonates, potassium hydroxide, sodium hydroxide, aqueous ammonia, monocarboxylic acids, dicarboxylic acids and polycarboxylic acids, which are used in the form of a mixture of combination thereof, as well as formalin.In addition, other additives may also be used, if necessary, including hard water softeners (such as inorganic phosphoric acids, aminopolycarboxylic acids, organic phosphoric acids, aminopolyphosphonic acids, phosphonocarboxylic acids), germicides (such as benzoisothiazolinones, isothiazolones, 4-thiazolinebenzimidazoles, halo- genated phenols), surfactants, brightners and hardeners. Two or more kinds of the same or different additives may be used together.

Moreover, as the post-processing film pH adjusting agent, it is preferable to add an ammonium salt such as ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium phosphate, ammonium sulfite, ammonium thiosulfate, and so on.

The present invention may be adopted to various color photographic materials. Typical examples are color reversal films and color reversal papers for slide or television. In addition, the present invention may also be adapted to white-and-black photographic materials utilizing a three-coupler admixture, as described in Research Disclosure, No. 17123 (July, 1978).

Now, the present invention will be explained in greater detail by reference to the following examples, which do not limit the scope of the present invention.

Example 1 As shown in the following Table 2, silver iodobromide emulsions (iodine content: 3 mol%) were prepared. Using these samples of the present invention and comparative samples were formed.

TABLE 2 Average Position of Samples Shape Grain Size Latent Image 4lem) (A) Tabular 0.7 Surface part (B) Tabular 0.7 Inner part (C) Tabular 0.4 Surface part (D) Tabular 0.4 Inner part (E) Spherical 0.7 Surface part (G) Spherical 0.4 Surface part (H) Spherical 0.4 Inner part (I) Octahedral 0.7 Surface part (K) Octahedral 0.4 Surface part (L) Octahedral 0.4 Inner part (M) Cubic 0.7 Surface part (o) Cubic 0.4 Surface part (P) Cubic 0.4 Inner part The preparation of the emulsions is described in detail hereunder.

(1) Preparation of emulsions comprising tabular grains: A silver nitrate-containing aqueous solution and an aqueous solution containing KBr and Kl were added to a gelatin-containing aqueous solution which did not contain KI and which was kept at 60 C, the pBr thereof being 1.3, during the course of 10 minutes, while the molar number of the halides was made equal to that of the silver nitrate, to obtain an emulsion containing tabular grains having an average aspect ratio of 7.0 in an amount of 50% or more of the total projected area of all grains. The silver iodobromide grains formed had an average grain diameter of 0.7 m as calculated in terms of the corresponding spheres, and contained 3 mol% of Agl.Next, the core emulsion formed was divided into two equivalent parts, each of which was thereafter processed under different conditions as mentioned below, to form shells over the cores.

Emulsion (A): Using the same silver nitrate solution and halogen solution as those in the aforesaid first core formation step, shells were deposited at 600C in the course of 3 minutes, which correspond to 50% of the molar number of the amount of the silver halides in the cores. Next, 2 mg of sodium thiosulfate and 2.5 mg of potassium chloroaurate were added to the emulsion, per 1 mol of silver contained therein, and then heated for 30 minutes at 700C for chemical sensitization.

Emulsion (B): The above-described cores were subjected to chemical sensitization under the same condition as the above Emulsion (A), and thereafter shells were deposited also under the same condition as Emulsion (A).

Emulsion (C) In the core formation of Emulsion (A), the temperature in the reaction solution was kept at 500C to obtain core grains having a size of 0.4 m. The following steps were the same as those in the formation of Emulsion (A).

Emulsion (D) Cores were prepared in the same manner as Emulsion (C), and the following steps were the same as those in the formation of Emulsion (B).

(2) Preparation of emulsions comprising thick tabular grains having an average aspect ratio of 3.0 A silver nitrate aqueous solution and an aqueous solution containing KBr and KI were added to a gelatin-containing aqueous solution which did not contain KI and which was kept at 65 C, the pBr thereof being 0.8, during the course of 5 minutes, while the molar amount of the halides was made equal to that of the silver nitrate, and thereafter the whole was subjected to physical ripening for 30 minutes to obtain an emulsion containing thick tabular grains having an average aspect ratio of 3.0. The silver iodobromide grains formed had an average grain diameter of 0.7 ,um, as calculated in terms of the corresponding spheres, and contained 3 mol% of Agl. Next, the core emulsion formed was divided into two equivalent parts.In the same manner as the formation of the above Emulsion (A), the resulting emulsion was treated for sehll formation and subjected to chemical sensitization to obtain Emulsion (E).

Emulsion (G): In the core formation of Emulsion (E), the temperature in the reaction container was kept at 550C to obtain core grains having a size of 0.4 item, and the followong steps were the same as those in the formation of emulsion (A).

Emulsion (H): Cores were prepared in the same manner as Emulsion (G), and the following steps were the same as those in the formation of Emulsion (B).

(3) Preparation of monodispersed emulsion having (111) crystal habit: A silver nitrate-containing aqueous solution and an aqueous solution containing KBr and KI were added to a gelatin-containing aqueous solution which was kept at 70 C, while the pBr value in the reaction system was kept to 3.3, for 30 minutes by double jetting, to obtain a monodispersed emulsion having (111) crystal habit.

The emulsion particles formed had an average diameter of 0.7 ,um, as calculated in terms of the corresponding spheres, and contained 3 mol% of Agl. Next, the core emulsion formed was divided into two equivalent parts. In the same manner as the formation of the above Emulsions (A) and (B), the resulting emulsion was treated for shell formation and subjected to chemical sensitization to obtain Emulsion (I).

Emulsion (K): In the core formation of Emulsion (I), the temperature in the reaction container was kept at 550C to obtain core grains having a size of 0.4 ,um, and the following steps were the same as those in the formation of Emulsion (A), with the exception that the pBr in the reaction system was kept to 3.3 for shell formation.

Emulsion (L): Cores were prepared in the same manner as Emulsion (K), and the following steps were the same as those in the formation of Emulsion (B), with the exception that the pBr in the reaction system was kept to 3.3 for the shell formation.

(4) Preparation of monodispersed emulsion having (100) crystal habit: In the same manner as Emulsions (I), (K) and (L) with the exception that the pBr in the reaction system was changed to 4.5 in the formation of grains, other Emulsions (M), (0) and (P) each comprising a mono-dispersed system of cubic grains were obtained, which were different from Emulsions (I), (K) and (L), respectively, only in the point of the crystal habit.

Multiple layers each comprising the following composition, individually, were provided on a cellulose triacetate film support, which had been subbed with a subbing layer, to obtain multilayer color photographic materials. These were Samples Nos. 101 to 108.

First Layer: Antihalation Layer Gelatin layer containing the following components (dry thickness: 1 ,um): Black colloidal silver 0.25 g/m2 UV Absorbent U-l 0.04 g/m2 UV Absorbent U-2 0.1 g/m2 UV Absorbent U-3 0.1 g/m2 High Boiling Point Organic Solvent 0-1 0.1 cc/m2 Second Layer: Intermediate Layer Gelatin layer containing the following components (dry thickness: 1 ism): Compound H-l 0.05 g/m2 High Boiling Point Organic Solvent 0-2 0.05 cc/m2 Third Layer:First Red-Sensitive Emulsion Layer Gelatin layer containing the folowing components (dry thickness: 1 ,us): Silver Bromide Emulsion (G) spectrally sensitized with Sensitizer Dye S-l and Sensitizer Dye S-2 0.5 g (silver)/m2 Coupler C-1 0.2 g/m2 Coupler C-2 0.05 g/m2 High Boiling Point Organic Solvent 0-2 0.12 cc/m2 Fourth Layer: Second Red-Sensitive Emulsion Layer Gelatin layer containing the following components (dry thickness: 2.5 im): Silver Bromide Emulsion (E) spectrally sensitized with Sensitizer Dye S-1 and Sensitizer Dye S-2 0.8 g (silver)/m2 Coupler C-l 0.55 g/m2 Coupler C-2 0.14 g/m2 High Boiling Point Organic Solvent 0-2 0.33 cc/m2 Fifth layer:Intermediate Layer Gelatin layer containing the following components (dry thickness: 1 Am): Compound H-l 0.1 g/m2 High Boiling Point Organic Solvent 0-2 0.1 cc/m2 Sixth Layer: First Green-Sensitive Emulsion Layer Gelatin layer containing the following components (dry thickness: 1 'tom): Silver lodobromide Emulsion (G) containing Sensitizer Dye S-3 and Sensitizer Dye S-4 0.7 g (silver)/m2 Coupler C-3 0.35 g/m2 High Boiling Point Organic Solvent 0-2 0.26 cc/m2 Seventh Layer: Second Green-Sensitive Emulsion Layer Gelatin layer containing the following components (dry thickness: 2.5 Am): Silver lodobromide Emulsion (E) containing Sensitizer Dye S-3 and Sensitizer Dye S-4 0.7 g (silver)/m2 Coupler C-4 0.25 g/m2 High Boiling Point Organic Solvent 0-2 0.05 cc/m2 Eighth Layer:Intermediate Layer Gelatin layer containing the following components (dry thickness: 1 Am): Compound H-l 0.05 g/m2 High Boiling Point Organic Solvent 0-2 0.1 g/m2 Ninth Layer: Yellow Filter Layer Gelatin layer containing the following components (dry thickness: 1 m): Yellow colloidal silver 0.1 g/m2 Compound H-l 0.02 g/m2 Compound H-2 0.03 g/m2 High Boiling Point Organic Solvent 0-2 0.04 cc/m2 Tenth Layer: First Blue-Sensitive Emulsion Layer (as described in the following Table 3) Gelatin layer containing the following components (dry thickness: 1.5 ism): Silver iodobromide emulsion containing Sensitizer Dye S-5 0.6 g (silver)/m2 Coupler C-5 0.5 g/m2 High Boiling Point Organic Solvent 0-2 0. 1 cc/m2 Eleventh Layer:Second Blue-Sensitive Emulsion Layer (as described in the following Table 3) Gelatin layer containing the following components (dry thickness: 3 Am): Silver iodobromide emulsion containing Sensitizer Dye S-5 1.1 g (silver)/m2 Coupler C-5 1.2 g/m2 High Boiling Point Organic Solvent 0-2 0.23 cc/m2 Twelfth Layer: First Protective Layer Gelatin layer containing the following components (dry thickness: 2 Am): UV Absorbent U-l 0.02 g/m2 UV Absorbent U-2 0.03 g/m2 UV Absorbent U-3 0.03 g/m2 UV Absorbent U-4 0.29 g/m2 High Boiling Point Organic Solvent 0-1 0.28 cc/m2 Thirteenth Layer:Second Protective Layer Gelatin layer containing the following components (dry thickness: 0.8 m): Surface-fogged fine silver iodobromide emulsion (iodine content: 1 mol%, average grain size: 0.06 Am) 0.1 g (silver)/m2 Polymethyl methacrylate grains (average grain size: 1.5 ism) 400 mg/m2 To each of the above layers were added a Gelatin Hardener H-l and a surfactant, in addition to the above components.

Compounds as used in the preparation of the present samples are given below.

Each of samples Nos. 101 to 108, as prepared above, was subjected to white wedge exposure and then developed according to the following development treatment: Treating Steps: Step Time Temperature (min) First Development 6 38 C Water Washing 2 380C Reversal 2 38 C Color Development 6 380C Compensation 2 380C Bleaching 6 380C Fixation 4 380C Water Washing 4 380C Stabilization 1 Normal Temperature Drying The following treating solutions were used in each treatment.

Developer for the First Development: Water 700 ml Tetrasodium Nitrilo-N,N,N-trimethylenephosphonate 2 g Sodium Sulfite 20 g Hydroquinone Monosulfonate 30 g Sodium Carbonate (monohydrate) 30 g 1-Phenyi-4-methyl-4-hydroxymethyl-3-pyrazolidone 2 9 Potassium Bromide 2.5 g Potassium Thiocyanate 1.2 g Potassium lodide (0.1% solution) 2 ml Water to make 1,000 ml Reversal Solution: Water 700 ml Tetrasodium Nitrilo-N,N,N-trimethylenephosphonate 3 g Stannous Chloride (dihydrate) ig p-Aminophenol 0.1 9 Sodium Hydroxide 8g Glacial Acetic Acid 15 ml Water to make 1,000 ml Color Developer:: Water 700 ml Tetrasodium Nitrilo-N,N,N-trimethylenephosphonate 3 g Sodium Sulfite 7g Sodium tert-Phosphate (12 hydrate) 36 g Potassium Bromide 1 g Potassium lodide (0.1% solution) 90 ml Sodium Hydroxide 3g Citrazinic Acid 1.5 g N-Ethyl-N-(ss-methanesulfonamidoethyl)-3-methyl-4-aminoaniline Sulfate 11 9 3,6-Dithiaoctane-1,8-diol lg Water to make 1,000 ml Compensating Solution: Water 700 ml Sodium Sulfite 12 g Sodium Ethylenediaminetetraacetate 8g (dihydrate) Thioglycerin 0.4 ml Glacial Acetic Acid 3 ml Water to make 1,000 ml Bleaching Solution: Water 800 ml Sodium Ethylenediaminetetraacetate 2 g (dihydrate) Ammonium Ethylenediaminetetraacetato 120 g Ferrate Dihydrate Potassium Bromide 100 g Water to make 1,000 ml Fixation Solution: : Water 800 ml Sodium Thiosulfate 80.0 g Sodium Sulfite 5.0 g Sodium Bisulfite 5.0 g Water to make 1,000 ml Stabilization Solution: Water 800 ml Formalin (37 wit%) 5.0 ml Fuji Driwel (surfactant made by 5.0 ml Fuji Photo Film Co., Ltd.) Water to make 1,000 ml The color reversal sensitivity is represented by the relative exposure to be required for increasing the density of the dye formed to be higher than the minimum density thereof by 0.2.

The sharpness is represented by MTF value as measured.

Regarding the MTF value, an explanation thereof is given in T.H. James, The Theory of the Photographic Process, 4th Ed., pages 596 and 604 (1977).

T A B L E 3 Relative Reversal Sensitivity MTF Value (20 bands/mm) 1st Blue- 2nd Blue- in Blue- Blue- Green- Red Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive Sample No. Emulsion Emulsion Layer Layer Layer Layer 101 (G) (E) 100 0.80 0.65 0.55 (Comparison) 102 (H) (E) 80 0.77 0.64 0.53 (Comparison) 103 (G) (A) 103 0.87 0.85 0.70 (Comparison) 104 (H) (A) 125 0.89 0.87 0.70 (Invention) 105 (G) (I) 97 0.76 0.62 0.53 (Comparison) 106 (H) (I) 78 0.74 0.63 0.50 (Comparison) 107 (G) (M) 100 0.75 0.60 0.51 (Comparison) 108 (H) (M) 80 0.75 0.62 0.52 (Comparison) As is apparent from the results in Table 3, the sample of the present invention is characterized by the simultaneous achievement of the improvement in the sensitivity of the blue-sensitive layer and the improvement in the sharpness of all the color-sensitive layers.

EXAMPLE 2 In the same manner as Sample No. 101, with the exception that the emulsions of the green sensitive emulsions layers in Sample No. 101 were replaced by those as given in the following Table 4, other Samples Nos. 109 to 113 were prepared, and the photographic characteristics thereof were compared with one another.

T A B L E 4 Relative Reversal Sensitivity MTF Value (20 bands/mm) 1st Green- 2nd Green- in Green- Green- Red Sensitive Sensitive Sensitive Sensitive Sensitive Sample No. Emulsion Emulsion Layer Layer Layer 101 (G) (E) 100 0.65 0.55 (Comparison) 109 (H) (E) 85 0.62 0.54 (Comparison) 110 (G) (A) 105 0.82 0.69 (Comparison) 111 (H) (A) 130 0.84 0.70 (Invention) 112 (G) (M) 100 0.63 0.52 (Comparison) 113 (H) (M) 85 0.60 0.50 (Comparison) As is apparent from the results in Table 4, the sample of the present invention is characterized by the simultaneous achievement of the improvement in the sensitivity of the greensensitive layer and the improvement in the sharpness of the green-sensitive layer and the redsensitive layer.

EXAMPLE 3 In the same manner as Sample No. 101, with the exception that the emulsions of the bluesensitive emulsion layers in Sample No. 101 were replaced by those as given in the following Table 5, other Samples Nos. 115 to 128 were prepared, and the photographic characteristics thereof were compared with one another.

T A B L E 5 Relative Reversal Sensitivity MTF Value (20 bands/mm) 1st Blue- 2nd Blue- in Blue- Blue- Green- Red Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive Sample No. Emulsion Emulsion Layer Layer Layer Layer 101 (G) (E) 100 0.80 0.65 0.55 (Comparison) 115 (C) (A) 104 0.93 0.91 0.80 (Comparison) 116 (D) (A) 123 0.92 0.91 0.80 (Invention) 103 (G) (A) 103 0.87 0.85 0.70 (Comparison) 104 (H) (A) 125 0.89 0.87 0.70 (Invention) 117 (K) (A) 100 0.86 0.83 0.68 (Comparison) 118 (L) (A) 129 0.87 0.84 0.70 (Invention) 119 (O) (A) 101 0.87 0.83 0.70 (Comparison) 120 (P) (A) 127 0.87 0.83 0.71 (Invention) (cont'd) Relative Reversal Sensitivity MTF Value (20 bands/mm) 1st Blue- 2nd Blue- in Blue- Blue- Green- Red Sensitive Sensitive Sensitive Sensitive Sensitive Sensitive Sample No.Emulsion Emulsion Layer Layer Layer Layer 121 (C) (B) 103 0.92 0.91 0.81 (Comparison) 122 (D) (B) 133 0.92 0.92 0.83 (Invention) 123 (G) (B) 102 0.88 0.84 0.69 (Comparison) 124 (H) (B) 130 0.89 0.87 0.70 (Invention) 125 (K) (B) 101 0.86 0.84 0.69 (Comparison) 126 (L) (B) 125 0.86 0.85 0.69 (Invention) 127 (O) (B) 100 0.86 0.82 0.71 (Comparison) 128 (P) (B) 125 0.88 0.83 0.71 (Invention) Table 5 proves the fact that the samples having a first blue-sensitive emulsion layer comprising internally sensitized grains and a second blue-sensitive emulsion layer comprising tabular grains capable of forming a latent image on the surfaces of the grains or in the inner part thereof are characterized by the simultaneous achievement of the improvement in the sensitivity of the bluesensitive layer and the sharpness of all the color-sensitive layers.

EXAMPLE 4 In the same manner as Sample No. 101, with the exception that the emulsions of the greensensitive emulsion layers in Sample No. 101 were replaced by those as given in the following Table 6, other Samples Nos. 129 to 133 were prepared, the photographic characteristics thereof were compared with one another.

T A B L E 6 Relative Reversal Sensitivity MTF Value (20 bands/mm) 1st Green- 2nd Green- in Green- Green- Red Sensitive Sensitive Sensitive Sensitive Sensitive Sample No. Emulsion Emulsion Layer Layer Layer 101 (G) (E) 100 0.65 0.55 (Comparison) 129 (C) (A) 106 0.90 0.73 (Comparison) 130 (D) (A) 140 0.93 0.75 (Invention) 131 (D) (B) 143 0.94 0.75 (Invention) 132 (O) (A) 104 0.82 0.71 (Comparison) 133 (P) (A) 139 0.84 0.70 (Invention) Table 6 proves the fact the samples having a first green-sensitive emulsion layer comprising internally sensitized grains and a second green-sensitive emulsion comprising tabular grains are characterized by the simultaneous achievement of the improvement in the sensitivity of the green-sensitive layer and the sharpness of the green-sensitive layer and the red-sensitive layer.

In the above description, the present invention is explained in detail; and in conclusion, the multilayer silver halide color reversal photographic materials of the present invention comprise plural blue-sensitive, green-sensitive and red-sensitive silver halide emulsion layers each having a different sensitivity, which are characterized in that specific tabular grains are incorporated in the layers of high sensitivity and/or middle sensitivity thereby to improve the sharpness of the emulsion layers, especially those positioned in the inner parts of the laminated layers, owing to the optical characteristics of the tabular grains. Despite of the incorporation of the tabular grains, the present photographic materials are almost free from any defects which will result from the incorporation of the grains.In this connection, it is noted that the tabular grains especially have a high solution physical development activity in a first development for color reversal treatment.

This is because the silver halides of the above-described tabular grains are thin and have a large surface area, and these tabular silver halide grains will cause to excessively accelerate the dissolution of other photosensitive silver halide grains of smaller sizes contained in the emulsion layers adjacent to the tabular grain-containing emulsion layer, especially in the emulsion layer of lower sensitivity, whereby the sensitivity of surface-sensitive grains is lost or deteriorated. In view of such circumstances, internally sensitized silver halide grains are incorporated in the emulsion layer which has substantially the same color sensitivity as that of the tabular silver halide grain-containing emulsion layer but has a lower sensitivity than this layer, in the photographic materials of the present invention, whereby the natural development may be attained in the light-sensitive grains contained in the photographic material, to obtain color positive images of a desired gradation reproduction and well balanced gradation. In particular, color reversal photographic materials are required to have a delicate final quality. In view of such requirement, the color reversal photographic materials of the present invention are especially advantageous as having a high image quality and a high treatment stability.

Claims (17)

1. A color reversal photographic material which comprises, on a support, a plurality of silver halide photographic emulsion layers, at least two of which have substantially the same color sensitivity in the visible spectrum, and of such layers of the same color sensitivity: in one layer (a) the silver halide grains which provide at least 50% of the total projected area of all the silver halide grains in that layer are tabular silver halide grains having an average aspect ratio, namely the ratio of the grain equivalent diameter to thickness, of 5:1 or more, and another layer (b) has a lower degree of sensitivity than that of layer (a) and contains silver halide grains each comprising a core and a shell, and at least the surface of the core has been chemically sensitized.

2. A color reversal photographic material as claimed in Claim 1, wherein the molar ratio of silver ion in the core and shell of the core/shell grains is 1:1 to 19:1.

3. A core reversal photographic material as claimed in Claim 1 or 2, wherein the diameter, calculated in terms of corresponding spherical grains, of the core/shell grains is not more then 3 microns.

4. A color reversal photographic material as claimed in Claim 1, 2 or 3, wherein the core/shell grains are composed of silver bromoiodide containing not more than 40 mol% of silver iodide.

5. A color reversal photographic material as claimed in any preceding claim, wherein said cores of the grains were chemically sensitized with sodium thiosulfate and a gold salt.

6. A color reversal photographic material as claimed in any preceding claim, wherein the core/shell grains are of tabular, octahedral, cubic, spherical or tetradecahedral shape.

7. A color reversal photographic material as claimed in any preceding claim, wherein the tabular grains constitute at least 70% of the total projected area of the lever (a).

8. A color reversal photographic material as claimed in any preceding claim, wherein the tabular silver halide grains have a thickness of 0.05 to 0.3 micron.

9. A color reversal photographic material as claimed in any preceding claim, wherein the tabular silver halide grains have a diameter, calculated in terms of corresponding circular grains, of 0.5 to 3.0 micron.

10. A color reversal photographic material as claimed in any preceding claim, wherein the tabular silver halide grains have an aspect ratio of 5:1 to 8:1.

11. A color reversal photographic material as claimed in any preceding claim, wherein the tabular silver halide grains are composed of silver bromoiodide, silver bromide, silver bromoiodo- chloride or a mixture thereof.

12. A color reversal photographic material as claimed in any preceding claim, wherein the tabular grains are of the type which form internal latent images.

13. A color reversal photographic material as claimed in any preceding claim, which contains at least two blue-sensitive, at least two red-sensitive and at least two green-sensitive layers of the same color sensitivity and each comprising layers of type (a) and (b).

14. A color reversal photographic material as claimed in Claim 1, substantially as hereinbefore described in any of the samples of the Examples which illustrate the invention.

15. A method of color photography, which comprises imagewise exposure and color reversal development of a color photographic material as claimed in any preceding claim.

16. A method as claimed in Claim 15, wherein the first developer of the reversal development is a black-and-white developer containing a silver halide solvent.

17. A method as claimed in Claim 15, substantially as hereinbefore described in any of the samples of the Examples which illustrate the invention.