JPH0667327A - Silver halide photographic emulsion - Google Patents

Abstract

PURPOSE:To provide a silver halide photographic emulsion having improved pressure resistance, contg. single dispersed particles and excellent in graininess. CONSTITUTION:This silver halide emulsion contains silver halide particles obtd. by growing seed crystals passed through a washing process and made practically of silver iodobromide. Each of the seed crystals consists of a core made of silver iodobromide contg. less than 7mol% silver iodide and a shell made of silver iodobromide having a higher silver iodide content than the silver iodobromide of the core at the outside of the core. The seed crystals are used in a single dispersed state and 60% or more of the total number of the seed crystals are preferably twin particles each having two twin faces parallel to the principal plane. The pref. iodine content of the shell is 10mol% or more, especially 15-40mol%.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a silver halide emulsion useful in the field of photography, and more particularly to a silver halide emulsion having remarkably improved pressure resistance and graininess.

[0002]

2. Description of the Related Art In recent years, photographing opportunities have increased with the spread of cameras, and the demand for high-sensitivity and high-quality silver halide photographic light-sensitive materials has been increasing. However, since the silver halide contained in the silver halide light-sensitive material as a photosensitive material has the property of being sensitive to pressure, it is more and more sensitive to pressure as the sensitivity is increased. When the surface layer becomes scratched, pressure fog will occur.
It causes defects such as pressure desensitization and has a fatal adverse effect on photographic images.

On the other hand, the manufacturing process of silver halide photographic light-sensitive materials, that is, the processes such as coating, drying and processing are accelerated, the packaging machine is complicated in the processing process, the product form is diversified or the camera is made compact. Since the use conditions such as automatic winding and rewinding have been diversified, etc., and generally tend to be manufactured or used under severe conditions, it is more and more necessary to prevent the abrasion resistance or the pressure resistance induced by the abrasion damage. It has become an important issue.

Japanese Patent Publication No. 3124
No. 5 discloses that a high iodide layer is provided on the inner nucleus having a low silver iodide content (0 to 3 mol%) by a halogen substitution method with potassium iodide or a control double jet method, and a low iodide layer is provided outside thereof. Techniques have been disclosed for improving pressure resistance by means of emulsions consisting of layered core / shell structured silver halide grains. However, in this publication, since a desalting step is performed between the internal low-iodine nucleus and the high-iodine layer, when pressure is applied to the particles, stress is concentrated on the interface, and defects are easily formed,
It was found that satisfactory pressure resistance could not be obtained.

JP-A-60-254032 discloses a halogen having a distinct core / shell structure having a high silver iodide content core (10 to 45 mol%) and a low silver iodide content shell (0 to 5 mol%). Silver halide emulsions are disclosed. However, in this publication, since grains are formed by a continuous method from high iodine nucleation to growth, the double parallel twin ratio is significantly reduced, and the cause of deterioration of grain size distribution of grains is Become. Therefore, the graininess is deteriorated and the pressure resistance is insufficient. As described above, it is difficult for the conventional technique to satisfy both pressure resistance and graininess.

[0006]

OBJECT OF THE INVENTION It is an object of the present invention to provide a silver halide emulsion which has improved pressure resistance, is monodispersed in grain and is excellent in graininess.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present inventors have conducted intensive studies and found that the object of the present invention can be achieved by the following configurations. That is, the present invention is achieved by each of the following inventions.

(1) A silver halide emulsion containing silver halide grains consisting essentially of silver iodobromide obtained by growing seed crystals that have been washed with water, the seed crystals being silver iodide. 7
The core is composed of a silver iodobromide content of less than 1 mol%, and a shell composed of silver iodobromide having a higher silver iodide content than the core silver iodobromide is provided outside the core, and the seed crystal is a single crystal. A silver halide emulsion characterized by being dispersed.

(2) The seed crystal described in the above item (1) is characterized in that 60% or more of the total number of grains is composed of twin grains having two twin planes parallel to the main plane. Silver halide emulsion.

The present invention will be described in detail below. In the present invention, the seed emulsion means a core made of silver iodobromide containing less than 7 mol% of silver iodide, and an iodobromide having a silver iodide content higher than that of silver iodobromide in the core outside the core. An emulsion obtained by forming grains composed of a silver shell and washing with water. Here, the iodide content of the core portion is less than 7 mol%, preferably 6 mol% or less, and more preferably 2 to 6 mol%.

The iodine content of the shell portion is preferably 10 mol% or more, more preferably 15 to 40 mol%. The average silver iodide content of the seed is 10 mol% or more, more preferably 15 to 40 mol%. The average grain size of the silver halide emulsion of the present invention is 0.03 μm or less, preferably 0.05 to 0.30 μm, and particularly preferably 0.10 to 0.25 μm. Here, the average particle diameter is defined as the particle size d _i of when the product of the frequency of the particle diameter n _i and d _i ³ having a particle size d _i is maximized. (3 significant digits,
The minimum digit is rounded to 4)

The particle size is determined, for example, by dispersing the particles so that they do not overlap with each other on a flat sample table, magnifying the image with an electron microscope at a magnification of 1 to 50,000, and measuring the particle diameter on the print or the area at the time of projection. Can be obtained by actually measuring.
(It is assumed that the number of measured particles is 1000 or more indiscriminately)
The seed emulsion grains according to the present invention refer to grains having two parallel twin planes. In the present invention, the grains preferably account for 60% or more of the total number of grains, and more preferably 70% or more. . Further, the shape of the seed particles is preferably a substantially regular hexagonal tabular particle, but may be octahedral, tetrahedral or spherical particles.

In the present invention, the monodisperse means that the coefficient of variation of particle diameter (standard deviation of particle diameter / average particle diameter × 100) is 30% or less, preferably 25% or less, more preferably 20%.
It is the following. The silver halide seed emulsion of the present invention can be obtained by a production method including a nucleation step, a growth step, an Ostwald ripening step, and a water washing step. The nucleation step in the present invention is a step of adding a water-soluble silver salt or a halide salt to a protective colloid solution to generate silver halide nuclei, which is a step before the maximum number of silver halide nuclei is reached. Is.

The growth step is performed by adding a water-soluble silver salt and a halide salt having a higher iodine content than the nucleation step so that new nuclei are not generated after the nucleation step, and the growth step is performed outside the nucleus. This is a step of providing a high iodine layer. What is Ostwald ripening?
This is a step of reducing the number of silver halide nuclei or crystal grains by ripening. The water washing step is a step of removing by-products, excess salts, and other unnecessary components.

The step of washing with water may be carried out by Nudell washing method in which gelatin is gelled, and inorganic salts, anionic surfactants, anionic polymers (eg polystyrene sulfonic acid), or gelatin derivatives (eg acylated gelatin). , Carbamoylated gelatin, etc.) may be used.

In the method for producing the seed emulsion used in the present invention, the temperature at the time of nucleation is 40 ° C. or higher, preferably 40 to 50 ° C., more preferably 40 to 45 ° C. The pBr at the time of nucleation is 0.1 to 2.5, preferably 0.6 to 2.0, more preferably 1.1 to 2.0. Other preferable conditions at the time of nucleation are gelatin concentration of 0.1 to 10 wt%, more preferably 0.5 to 5 wt%. The pH is 2.0 to 12.0, preferably 3.0 to 8.0. The addition rate of silver salt and halide salt in nucleation is 1.0 × 10 ⁻³ mol / min per liter of reaction solution.
3.0 mol / min, preferably 3.0 × 10 ^{−3 to} 5.0 ×
It is 10 ^-1 mol / min.

The growth step is the same as the nucleation step except that the iodide composition of the halide salt added is different. Preferred conditions for the Ostwald ripening step are: a silver halide solvent of 10 ^{−5 to} 2.0 mol / silver halide of 1 mol. The temperature is 50 ° C or lower, preferably 40 ° C or lower, more preferably 10 to 40 ° C. pH 2-13, more preferably 3-12. Gelatin concentration 0.1 to 10 wt%, more preferably 0.5 to 5 wt%. pBr 0.5-2.9, preferably 1.3-1.9.

The silver halide solvent used in the seed grain forming step used in the present invention is (a) US Pat.
71,157, 3,531,289, 3,57
4,628, JP-A-54-1019 and 54-15.
8917 and Japanese Patent Publication No. 58-30571, (b) JP-A-53-82408.
No. 55-29829 and No. 57-77736, (c) JP-A-53-144
No. 319, AgX solvent having a thiocarbonyl group sandwiched between an oxygen or sulfur atom and a nitrogen atom, (d)
Imidazoles, (e) sulfites, (f) thiocyanates, (g) described in JP-A No. 54-100717.
Ammonia, (h) ethylenediamines substituted by hydroxylalkyl described in JP-A-57-196228, (i) substituted mercaptotetrazoles described in JP-A-57-202531, (j) water-soluble bromide,
(K) Benzimidazole derivatives described in JP-A-58-54333 and the like can be mentioned.

Specific examples of these silver halide solvents (a) to (k) will be given below.

[0020]

[Chemical 1]

[0021]

[Chemical 2]

[0022]

[Chemical 3]

These solvents can be used in combination of two or more kinds. Preferred solvents include thioethers, thiocyanates, thioureas, ammonia and bromides, and particularly preferably a combination of ammonia and bromides.

An example of a preferred embodiment of the present invention will be described. At a pH of 10.8 to 12.0 and a temperature of 15 to 25 ° C., 0.4 to 1.0 mol / liter of ammonia and 0.03 to 0. Using 5 mol / liter in combination,
By ripening for 30 seconds to 10 minutes, an emulsion containing suitable seed grains was obtained. A water-soluble silver salt may be added for the purpose of controlling ripening during the seed grain forming step used in the present invention. The seed emulsion used in the present invention can be enlarged in the growing step.

The growth step means that there is substantially no generation of new nuclei and Ostwald ripening, and elements for growing silver halide crystals are replenished at a rate of 20 to 100% with respect to the critical growth rate at which new nuclei are generated. It is a process to do. In the growth step which can be carried out in the present invention, the growth conditions may be any of an acidic method, a neutral method and an ammonia method, and for example, JP-A Nos. 61-6643, 61-14630 and 61-61.
-112142, 62-157024, 62-
18556, 63-92942, 63-151.
No. 618, No. 63-163451, and No. 63-22023.
Known methods such as No. 8 and No. 63-311244 can be used.

The supplementary element for crystal growth is preferably performed at a rate of 20 to 100% with respect to the critical growth rate at which new nuclei are generated. The replenishment element can be either a water soluble silver salt and halide solution or a fine grain silver halide. The average silver iodide content of the silver halide obtained by growing the seed emulsion of the present invention is preferably 0.1 to 45 mol%, more preferably 0.5 to 20 mol%, particularly preferably 1 to 10 mol%. %.

The silver halide emulsion obtained by growing the seed emulsion of the present invention is silver iodobromide or iodobromide salt, and may be surface latent image type or internal latent image type. The silver halide emulsion obtained by growing the seed emulsion of the present invention is monodisperse and has a variation coefficient of grain size (standard deviation of grain size / average grain size × 1).
00) is 25% or less, preferably 20% or less, and more preferably 15% or less.

The shape of the silver halide emulsion obtained by growing the seed emulsion of the present invention is substantially octahedral, but it may be tabular, tetradecahedral or spherical grains. The silver halide emulsion obtained by growing the seed emulsion of the present invention can be chemically sensitized by a conventional method. Further, a dye known as a sensitizing dye in the photographic industry can be used to optically sensitize the dye in a desired wavelength range. The sensitizing dyes may be used alone or in combination of two or more.

An antifoggant, a stabilizer and the like can be added to the silver halide emulsion of the present invention. Known additives can be applied to the silver halide emulsion of the present invention and the light-sensitive material to which the emulsion is applied.

Useful photographic additives are Research Disclosure No. 17643, No. 18716 and N
o. 308119 (Respectively RD17643, R
D18716 and RD308119). The table below shows the locations.

[Items] [RD308119 [RD17643] [RD18716] page] Chemical sensitizer 996 Item III-A 23 648 Spectral sensitizer 996 IV-A-A, 23-24 648-9 B, C, D , H, I, J item Supersensitizer 996 IV-AE, 23-24 648-9 J item Antifoggant 998 VI 24-25 649 Stabilizer 998 VI 24-25 649

Known photographic additives which can be used in the silver halide emulsion of the present invention and the light-sensitive material to which the emulsion is applied are also described in the above Research Disclosure. The following table shows the relevant locations.

[Item] [Page of RD308119 [RD17643] [RD18716]] Color turbidity inhibitor 1002 Item VII-I 25 650 Dye image stabilizer 1001 VII-J 25 Whitening agent 998 V 24 Ultraviolet absorber 1003 VIII- C, 25-26 XIIIC paragraph Light absorber 1003 VIII 25-26 Light-scattering agent 1003 VIII Filter dye 1003 VIII 25-26 Binder 1003 IX 26 651 Antistatic agent 1006 XIII 27 650 Hardener 1004 X 26 651 Plasticizer 1006 XII 27 650 Lubricating oil 1006 XII 27 650 Activator / coating aid 1005 XI 26-27 650 Matting agent 1007 XVI Developer 1011 XXB Item (included in photosensitive material)

Various couplers can be used in the silver halide emulsion of the present invention and the light-sensitive material obtained by using the same, and specific examples thereof are described in the above-mentioned Research Disclosure. The following table shows the relevant locations.

[Item] [Page of RD308119] [RD17643] Yellow coupler 1001 VII-D item VII C to G item Magenta coupler 1001 VII-D item VII C to G item Cyan coupler 1001 VII-D item VII C to G item Colored coupler 1002 VII-G section VII G section DIR coupler 1001 VII-F section VII F section BAR coupler 1002 VII-F section Other useful residues 1001 VII-F section Release coupler Alkali-soluble coupler 1001 VII-E section

The additives used in the silver halide emulsion of the present invention and the light-sensitive material to which the emulsion is applied are RD308119.
It can be added by the dispersion method described in XIV.

In the silver halide emulsion of the present invention and the light-sensitive material to which the emulsion is applied, the above-mentioned RD17643 28 is used.
Pages, RD18716 pages 647-8 and RD30811.
The supports described in XVII of 9 can be used. The light-sensitive material obtained by using the silver halide emulsion obtained in the present invention includes the above-mentioned RD308119VII-K.
An auxiliary layer such as a filter layer or an intermediate layer described in the section can be provided.

The light-sensitive material obtained by using the silver halide emulsion of the present invention can have various layer constitutions such as the forward layer, the reverse layer and the unit constitution described in the above-mentioned RD308119VII-K. As the support, paper laminated with polyethylene or the like, polyethylene terephthalate film, baryta paper, cellulose acetate film or the like can be used.

The silver halide emulsion of the present invention comprises various color photographic light-sensitive materials represented by color negative films for general use or movies, color reversal films for slides or televisions, color papers, color positive films and color reversal papers. Can be preferably applied to.

In order to obtain a dye image by using the light-sensitive material to which the silver halide emulsion of the present invention is applied, a color development treatment which is generally known can be carried out after exposure. The light-sensitive material to which the silver halide emulsion of the present invention is applied is the above-mentioned RD17643.
28-29, RD18716, 647 and RD3
It can be developed by a usual method described in XIX of 08119.

[0041]

EXAMPLES Specific examples of the present invention will be described below, but the present invention is not limited thereto.

Example [Preparation of Comparative Emulsion Em-1] A comparative emulsion Em-1 was prepared by a continuous method from nucleation to growth under the following conditions.

[Preparation of Seed Emulsion I-1] A comparative seed emulsion I-2 comprising silver bromoiodide was prepared using the solution shown below.

[A1] Ocein gelatin 140 g Polyisopropylene-polyethyleneoxy-disuccinate sodium salt 10% methanol solution 1.2 ml Water 3500 ml

[B1] Silver Nitrate 58.5 g Water 98.4 ml

[C1] Ocein gelatin 2.0 g Potassium bromide 36.9 g Potassium iodide 5.7 g Water 98.4 ml

(Solution B2) 3.5N ammoniacal silver nitrate aqueous solution (however, the pH was adjusted to 9.0 with ammonium nitrate)

(Solution C2) 3.5N potassium bromide aqueous solution

(Solution D) Fine grain emulsion (*) consisting of 3% by weight of gelatin and 1.2 mol of silver iodide grains (average grain size: 0.05 μm).

* The preparation method is shown below. To 5000 ml of a 6.0% by weight gelatin solution containing 0.06 mol of potassium iodide, an aqueous solution containing 7.06 mol of silver nitrate and 7.06 mol of potassium iodide, respectively, was added.
000 ml was added over 10 minutes. The pH during fine particle formation was controlled to 2.0 using nitric acid, and the temperature was controlled to 40 ° C. After forming the particles, the pH was adjusted to 6.0 using an aqueous sodium carbonate solution.

(Solution E) A fine grain emulsion of silver iodobromide (average grain size 0.04 μm) containing 2 mol% of silver iodide prepared in the same manner as the silver iodide fine grain emulsion described in Solution D. . However, the temperature during the formation of the fine particles was controlled at 30 ° C.
3.68 mol (solution F) 1.75N potassium bromide aqueous solution (solution G) 56% by weight aqueous acetic acid solution

Solution B1 and C1 solution were added by a double jet method at a flow rate of 13.6 ml / minute for 7 minutes and 14 seconds into a container in which solution A1 solution kept at an average temperature of 60 ° C. was stirred. The pBr was kept at 2.0 with potassium bromide during the addition. After addition is complete 2
308 ml of an 8 wt% aqueous ammonia solution was added in 1 minute, and Ostwald ripening was performed for 5 minutes. Upon aging, the KBr concentration was 0.028 mol / liter, the ammonia concentration was 1.37 mol / liter, and the pH was 12.3. Immediately thereafter, acetic acid was added until the pH reached 7.2 for neutralization and aging was stopped.

Electron microscopic observation of the grains at this point revealed that they were hexagonal tabular grains having two twin planes parallel to each other (comparative seed emulsion I-1). The seed emulsion grains had an average grain size of 0.217 μm, a two-plane parallel twin plane ratio of 53% in terms of the number of all grains, and a broad distribution of 45%. Subsequently, in the same reaction vessel, solution B2, solution C2 and solution D were added by the simultaneous mixing method over a period of 178 minutes, and then solution E was continuously added over 7 minutes at a constant rate.
Seed crystals were grown to 0.806 μm.

Here, the addition rates of the solution B2 and the solution C2 were changed in a function-like manner with respect to time so as to be commensurate with the critical growth rate, and a large number of particles other than the growing seed crystal were generated and Ostwald ripening was performed to increase the number. It was added at an appropriate addition rate so as not to disperse. The solution D, that is, the silver iodide fine grain emulsion was supplied by changing the rate ratio (molar ratio) with the aqueous ammoniacal silver nitrate solution with respect to the particle size (addition time) as shown in Table 1 to obtain a core having a multiple structure. A / shell type silver halide emulsion was prepared.

By using the solutions F and G,
The pAg and pH during crystal growth were controlled as shown in Table 1. The pAg and pH were measured according to a conventional method using a silver sulfide electrode and a glass electrode. After grain formation, a desalting step is carried out according to the method described in Japanese Patent Application No. 3-41314, gelatin is then added and redispersed, and the mixture is added at 40 ° C.
The H was adjusted to 5.80 and the pAg was adjusted to 8.06. From the scanning electron micrograph of the obtained emulsion grains, the average grain size was 0.8.
It was confirmed to be an octahedral twin monodisperse emulsion having a thickness of 06 μm and a distribution of 37.0% (comparative emulsion Em-1).

[0056]

[Table 1] Addition time (min) Particle size (μm) Solution D pH pAg Flow rate ratio Intermediate layer 0.0 0.217 6.0 7.2 7.8 29.02 0.345 20.1 7.2 7 4.8 44.94 0.394 29.5 7.2 7.8 Core part 48.76 0.397 30.0 7.2 7.8 59.21 0.434 30.0 7.2 7.8 71 .32 0.466 30.0 7.2 7.8 Shell 74.05 0.476 28.9 7.2 7.8 parts 105.53 0.593 7.7 7.2 7.8 105.530 0.593 0.0 6.5 9.4 173.90 0.730 0.0 6.5 9.7 178.00 0.745 0.0 6.5 9.7

[Preparation of Seed Emulsion I-2] A comparative seed emulsion I-2 made of silver bromide was prepared using the solution shown below.

[A1] Ocein gelatin 40 g Potassium bromide 23.7 g Water 4000 ml

[B1] 600 g of silver nitrate 803 ml of water

[C1] Gelatin 16.1 g Potassium bromide 420 g Water 803 ml

[D1] Ammonia water (28%) 235 ml

Solution B1 and C1 solution were added by a double jet method at a flow rate of 62.8 ml / min into a container in which solution A1 solution kept at an average temperature of 40 ° C. was stirred. The flow rate was gradually increased 4 minutes and 46 seconds after the addition so that the final flow rate was 105 ml / min and the total addition time was 10 minutes and 45 seconds. The pBr was kept at 1.3 with potassium bromide during the addition. Thirty minutes after the addition was completed, the liquid temperature was adjusted to 60 ° C., the D1 liquid was added in one minute, and Ostwald ripening was carried out for 5 minutes. The concentration of KBr during aging is 0.028 mol / liter, the ammonia concentration is 0.63 mol / liter, and the pH is 11.7.
Met.

Immediately thereafter, acetic acid was added to neutralize until the pH reached 5.7, ripening was stopped, and desalting and washing were carried out by a conventional method (comparative emulsion I-2). When this seed emulsion grain was observed with an electron microscope, it was a spherical type having two twin planes parallel to each other. The average grain size of this seed emulsion grain is 0.44
μm, the ratio of two parallel twin planes is 68 in terms of the number of particles in all grains.
%, And the breadth of distribution was 17.0%.

[Preparation of Seed Emulsion I-3] Similar to Seed Emulsion I-2, the following solution was used to prepare Seed Emulsion I-3 of the present invention.

[A1] Ocein gelatin 40 g Potassium bromide 23.7 g Water 4000 ml

[B1] 180 g of silver nitrate 241 ml of water

[B2] Silver nitrate 420 g Water 562 ml

[C1] Gelatin 4.8 g Potassium bromide 119 g Potassium iodide 10.6 g Water 241 ml

[C2] Gelatin 11.3 g Potassium bromide 206 g Potassium iodide 123 g Water 562 ml

[D1] Ammonia water (28%) 235 ml

Liquid B1 and liquid C1 were added by a double jet method at a flow rate of 105 ml / min for 2 minutes and 18 seconds in a vessel in which liquid A1 kept at an average temperature of 40 ° C. was stirred. Subsequently, solution B2 and solution C2 were added by the double jet method at a flow rate of 50 ml / min for 11 minutes and 14 seconds. PB during addition
r was potassium bromide and was kept at 1.6. Thirty minutes after the addition was completed, the liquid temperature was raised to 20 ° C., the liquid D was added in one minute, and Ostwald ripening was carried out for 5 minutes.

During aging, the concentration of KBr is 0.03 mol / liter, the concentration of ammonia is 0.66 mol / liter, p
H was 11.7. Immediately thereafter, acetic acid was added to neutralize until the pH reached 5.7, ripening was stopped, and desalting and washing were carried out by a conventional method (inventive seed emulsion I-3). When the seed emulsion grains were observed with an electron microscope, they were hexagonal tabular grains having two twin planes parallel to each other. The average grain size of this seed emulsion grain is 0.217 μm, the ratio of two parallel twin planes is 75% in terms of the number of all grains, and the distribution is 18.5%.
Met.

[Preparation of Seed Emulsion I-4] Similar to Seed Emulsion I-3, the following solutions were used to prepare Seed Emulsion I-4 of the present invention.

[A1] Ocein gelatin 40 g Potassium bromide 23.7 g Water 4000 ml

[B1] 180 g of silver nitrate 241 ml of water

[B2] Silver nitrate 420 g Ammonia water 342 ml Water 562 ml

[C1] Gelatin 4.8 g Potassium bromide 119 g Potassium iodide 10.6 g Water 241 ml

[C2] Gelatin 11.3 g Potassium bromide 206 g Potassium iodide 123 g Water 562 ml

Liquid B1 and liquid C1 were added by a double jet method at a flow rate of 105 ml / min for 2 minutes and 18 seconds in a container in which liquid A1 kept at an average temperature of 40 ° C. was stirred. Subsequently, the flow rate of the B2 solution and the C2 solution was gradually increased from the flow rate of 8 ml / min by the double jet method to a final flow rate of 34.
Added at 6 ml / min for 28 minutes 15 seconds. The pBr was kept at 1.6 with potassium bromide during the addition.

After completion of the addition, Ostwald ripening was carried out for 5 minutes. Immediately thereafter, desalting and water washing were carried out by a conventional method (inventive seed emulsion I-4). The average grain size of the seed emulsion grains was 0.217 μm, and the ratio of twin parallel twin planes was 75% and the breadth of distribution was 18.5%.

Using the comparative seed emulsions (I-1 and I-2) and the seed emulsions (I-3 and I-4) used in the present invention, the comparative emulsion Em-2 and the single emulsion of the present invention were prepared under the following conditions. Dispersed twin crystal emulsions Em-3 and Em-4 were grown to prepare a twin crystal monodisperse emulsion. [Preparation of Comparative Emulsion (Em-2)]

(Solution A) Osein gelatin 61.0 g Distilled water 1963 ml Polyisopropylene-polyethyleneoxy-disuccinate sodium salt 10% methanol solution 2.5 ml Seed emulsion (I-2) 2.877 mol 28 Aqueous solution of ammonia by weight 308 ml 56% Aqueous solution of acetic acid 358 ml MeOH solution containing 0.001 mol of iodine 33.7 ml Distilled water to 3500 ml.

(Solution B) 3.5N ammoniacal silver nitrate aqueous solution. (However, the pH was adjusted to 9.0 with ammonium nitrate)

(Solution C) 3.5N potassium bromide aqueous solution

(Solution D) Fine grain emulsion consisting of 3% by weight of gelatin and silver iodide grains (average grain size: 0.05 μm) 1.4 mol (Solution E) Odor odor containing 2 mol% of silver iodide Fine grain emulsion consisting of fine silver halide grains (average particle diameter 0.04 μm) 3.68 mol (solution F) 1.75N potassium bromide aqueous solution (solution G) 56 wt% acetic acid aqueous solution

Solution B, solution C and solution D were added to solution A kept at 70 ° C. in the reaction vessel by the simultaneous mixing method over a period of 80 minutes, followed by solution E over 7 minutes. Then, the seed crystal was grown to 0.806 μm by itself at a constant rate. Here, the addition rates of the solution B and the solution C are changed in a function-like manner with respect to time so as to be commensurate with the critical growth rate, and polydispersion is not caused due to generation of small particles other than growing seed crystals and Ostwald ripening. Was added at an appropriate addition rate. The solution D, that is, the silver iodide fine grain emulsion is supplied by changing the rate ratio (molar ratio) with the aqueous ammoniacal silver nitrate solution with respect to the particle size (addition time) as shown in Table 2 to obtain a core having a multiple structure. A / shell type silver halide emulsion was prepared.

By using the solutions F and G,
The pAg and pH during crystal growth were controlled as shown in Table 2. The pAg and pH were measured according to a conventional method using a silver sulfide electrode and a glass electrode. After grain formation, a desalting step is carried out according to the method described in Japanese Patent Application No. 3-41314, gelatin is then added and redispersed, and the mixture is added at 40 ° C.
The H was adjusted to 5.80 and the pAg was adjusted to 8.06. From the scanning electron micrograph of the obtained emulsion grains, the average grain size was 0.8.
It was confirmed to be an octahedral twin monodisperse emulsion having a grain size of 06 μm and a distribution width of 12.0%.

[0088]

[Table 2] Addition time (min) Particle size (μm) Solution D pH pAg Flow rate ratio Intermediate layer 0.0 0.440 6.0 7.2 7.8 10.04 0.481 19.8 7.2 7 7.8 17.77 0.506 29.1 7.2 7.8 Core part 19.80 0.511 30.0 7.2 7.8 27.46 0.532 30.0 7.2 7.8 32 .81 0.548 30.0 7.2 7.8 shell 34.50 0.552 28.9 7.2 7.8 54.39 0.631 7.7 7.2 7.8 54.39 0. 631 0.0 6.5 9.4 7.6 72.72 0.730 0.0 6.5 9.4 79.68 0.745 0.0 6.5 9.7

[Preparation of Emulsion (Em-3, Em-4) of the Present Invention] The preparation amount of the seed emulsion (I-3, I-4) of the solution A was adjusted to 0.
An emulsion of the present invention was prepared in the same manner as Comparative Emulsion Em-2 except that the amount was 345 mol. The addition rates of solution B, solution C and solution D, pAg and pH were controlled as shown in Table 3. The scanning electron micrograph of the obtained emulsion grains showed that the average grain size was 0.806 μm and the distribution was 15.0%.
It was confirmed to be an octahedral twin monodisperse emulsion.

[0090]

Table 3 Addition time (min) Particle size (μm) Solution D pH pAg Flow rate ratio Intermediate layer 0.0 0.217 6.0 7.0 7.2 7.8 26.20 0.345 20.1 7.2 7 4.8 40.86 0.394 29.5 7.2 7.8 Core part 41.57 0.397 30.0 7.2 7.8 54.11 0.434 30.0 7.2 7.8 64 .89 0.466 30.0 7.2 7.8 Shell 67.98 0.476 28.9 7.2 7.8 96.53 0.593 7.7 7.2 7.8 96.53 0. 593 0.0 6.5 9.4 126.33 0.730 0.0 6.5 9.7 128.00 0.745 0.0 6.5 6.5 9.7

The results obtained are summarized in Table 4.

[0092]

Table 4 Emulsion name Seed emulsion Seed twin ratio% Seed grain size distribution% Grain size distribution% Em-1 (I-1) 53.0 45.0 37.0 Em-2 I-2 68.0 17. 0 12.0 Em-3 I-3 75.0 18.5 15.0 Em-4 I-4 75.0 18.5 15.0

[Preparation of Photosensitive Material] Obtained Emulsion Em-1
To Em-4, a gold-sulfur sensitizing dye is optimally applied, and using these emulsions, each layer having the following composition is sequentially formed on the triacetyl cellulose film support from the support side to obtain a multilayer structure. A color photographic light-sensitive material was produced. In all the following descriptions, the addition amount in the silver halide photographic light-sensitive material is shown in grams per 1 m ² unless otherwise specified. Also, the silver halide and colloid rights are shown in terms of silver. The sensitizing dye is shown by the number of moles per mole of silver.

First layer; antihalation layer (HC) Black colloidal silver 0.16 g Ultraviolet absorber (UV-1) 0.30 g Gelatin 1.70 g

Second layer; intermediate layer (IL-1) gelatin 0.80 g

Third layer: low-sensitivity red-sensitive emulsion layer (RL) Silver iodobromide emulsion (average grain size 0.3 μm) 0.40 g Sensitizing dye (S-1) 1.2 × 10 ⁻⁴ ( Mol / silver 1 mol) Sensitizing dye (S-2) 0.2 × 10 ⁻⁴ (mol / silver 1 mol) Sensitizing dye (S-3) 2.0 × 10 ⁻⁴ (mol / silver 1 mol) Sensitizing dye (S-4) 1.2 × 10 ⁻⁴ (mol / silver 1 mol) Cyan coupler (C-1) 0.33 g Colored cyan coupler (CC-1) 0.05 g High boiling solvent (Oil-1) ) 0.30g gelatin 0.55g

Fourth Layer: Medium Sensitivity Red Sensitive Emulsion Layer (RM) Silver Iodobromide Emulsion (Average Grain Size 0.4 μm) 0.48 g Sensitizing Dye (S-1) 1.5 × 10 ⁻⁴ ( Mol / silver 1 mol) Sensitizing dye (S-2) 0.2 × 10 ⁻⁴ (mol / silver 1 mol) Sensitizing dye (S-3) 2.5 × 10 ⁻⁴ (mol / silver 1 mol) Sensitizing dye (S-4) 1.5 × 10 ⁻⁴ (mol / silver 1 mol) Cyan coupler (C-1) 0.30 g Colored cyan coupler (CC-1) 0.05 g DIR compound (D-1) 0.03g High boiling point solvent (Oil-1) 0.40g Gelatin 0.60g

Fifth layer: high-sensitivity red-sensitive emulsion layer (RH) Silver iodobromide emulsion (average grain size 0.55 μm) 0.66 g Sensitizing dye (S-1) 1.0 × 10 ⁻⁴ ( Mol / silver 1 mol) Sensitizing dye (S-2) 0.2 × 10 ⁻⁴ (mol / silver 1 mol) Sensitizing dye (S-3) 1.7 × 10 ⁻⁴ (mol / silver 1 mol) Sensitizing dye (S-4) 1.0 × 10 ⁻⁴ (mol / silver 1 mol) Cyan coupler (C-2) 0.10 g Colored cyan coupler (CC-1) 0.01 g DIR compound (D-1) 0.02g High boiling point solvent (Oil-1) 0.15g Gelatin 0.53g

Sixth layer; intermediate layer (IL-2) gelatin 0.80 g

Seventh layer: low-sensitivity green-sensitive emulsion layer (GL) Silver iodobromide emulsion (average grain size 0.4 μm) 0.60 g Silver iodobromide emulsion (average grain size 0.3 μm) 0.40 g Sensitizing dye (S-1) 0.6 × 10 ^-4 (mol / silver 1 mol) Sensitizing dye (S-5) 5.1 × 10 ^-4 (mol / silver 1 mol) Magenta puller (M-1) ) 0.55 g Colored magenta coupler (CM-1) 0.07 g DIR compound (D-2) 0.03 g High boiling point solvent (Oil-2) 0.70 g Gelatin 1.56 g

Eighth layer: high-sensitivity green-sensitive emulsion layer (GH) Silver iodobromide emulsion (Em-1) 0.60 g Sensitizing dye (S-6) 1.5 × 10 ⁻⁴ (mol / silver) 1 mol) Sensitizing dye (S-7) 1.5 × 10 ⁻⁴ (mol / silver 1 mol) Sensitizing dye (S-8) 1.5 × 10 ⁻⁴ (mol / silver 1 mol) Magenta puller ( M-1) 0.06 g Magenta puller (M-2) 0.02 g Colored magenta puller (CM-2) 0.02 g DIR compound (D-3) 0.002 g High boiling point solvent (Oil-2) 0.15 g Gelatin 0.45g

Ninth layer: Yellow filter layer (YC) Yellow colloidal silver 0.12 g Additive (HS-1) 0.20 g Additive (HS-2) 0.14 g High boiling solvent (Oil-2) 0.18 g Gelatin 0.80g

Layer 10: Low-sensitivity blue-sensitive emulsion layer (BL) Silver iodobromide emulsion (average grain size 0.4 μm) 0.18 g Silver iodobromide emulsion (average grain size 0.3 μm) 0.35 g Sensitizing dye (S-9) 5.1 × 10 ⁻⁴ (mol / silver 1 mol) Sensitizing dye (S-10) 2.0 × 10 ⁻⁴ (mol / silver 1 mol) Yellow coupler (Y-1) ) 0.58 g Yellow coupler (Y-2) 0.30 g High boiling point solvent (Oil-2) 0.15 g Gelatin 1.20 g

Eleventh layer: High-sensitivity blue-sensitive emulsion layer (BH) Silver iodobromide emulsion (average grain size 0.65 μm) 0.45 g Sensitizing dye (S-9) 2.8 × 10 ⁻⁴ ( Mol / silver 1 mol) sensitizing dye (S-10) 1.0 × 10 ⁻⁴ (mol / silver 1 mol) yellow coupler (Y-1) 0.10 g high boiling solvent (Oil-2) 0.04 g gelatin 0.50g

Twelfth layer; First protective layer (PRO-1) Silver iodobromide (average particle size: 0.07 μm) 0.30 g UV absorber (UV-1) 0.07 g UV absorber (UV-2) 0.10 g Additive (HS-1) 0.25 g High boiling point solvent (Oil-2) 0.07 g High boiling point solvent (Oil-3) 0.07 g Gelatin 0.80 g

Thirteenth layer; Second protective layer (PRO-3) Alkali-soluble matting agent (average particle size 2 μm) 0.13 g Polymethyl methacrylate (average particle size 3 μm) 0.02 g Gelatin 0.50 g

In each layer, in addition to the above composition, a coating aid Su-1, a dispersion aid Su-2, hardeners H-1 and H-2,
Dyes AI-1 and AI-2 were added appropriately.

[0108]

[Chemical 4]

[0109]

[Chemical 5]

[0110]

[Chemical 6]

[0111]

[Chemical 7]

[0112]

[Chemical 8]

[0113]

[Chemical 9]

[0114]

[Chemical 10]

[0115]

[Chemical 11]

Table 5 also shows the emulsions Em-1 to Em-4.
In the same manner as described above, a multilayer color photographic light-sensitive emulsion was prepared by using each of these emulsions instead of Em-1.

[0117]

[Table 5] Sample name 101 102 103 104 Emulsions used Em-1 Em-2 Em-3 Em-4

Each of the samples prepared as described above was subjected to wedge exposure using white light and then subjected to the development processing described below.

Processing Steps 1. Color development 3 minutes 15 seconds 38.0 ± 0.1 ° C 2. Bleach 6 minutes 30 seconds 38.0 ± 3.0 ° C 3. Washing with water 3 minutes 15 seconds 24-41 ° C 4. Stationary 6 minutes 30 seconds 38.0 ± 3.0 ° C 5. Washing with water 3 minutes 15 seconds 24-41 ° C 6. Stabilization 3 minutes 30 seconds 38.0 ± 3.0 ° C 7. Dryness 50 ° C or less The composition of the treatment liquid used in each treatment step is as follows.

[Color Developer] 4-Amino-3-methyl-N-ethyl-N- (β-hydroxyethyl) -aniline ・ sulfate 4.75 g anhydrous sodium sulfite 4.25 g hydroxylamine 1/2 sulfate 2 0.0 g anhydrous potassium carbonate 37.5 g sodium bromide 1.3 g nitrilotriacetic acid trisodium salt (monohydrate) 2.5 g potassium hydroxide 1.0 g water to make 1 liter, pH = Adjust to 10.1.

[Bleach] Ethylenediaminetetraacetic acid iron ammonium salt 100.0 g Ethylenediaminetetraacetic acid diammonium salt 10.0 g Ammonium bromide 150.0 g Glacial acetic acid 10.0 g Water was added to make 1 liter, and aqueous ammonia was added. Using pH
= Adjust to 6.0.

[Fixer] Ammonium thiosulfate 175.0 g Anhydrous sodium sulfite 8.5 g Sodium metasulfite 2.3 g Water was added to make 1 liter, and pH was adjusted to 6.0 with acetic acid.
Adjust to.

[Stabilizing Solution] Formalin (37% aqueous solution) 1.5 ml Conidax (manufactured by Konica Corporation) 7.5 ml Water is added to make 1 liter.

Each of the obtained samples was evaluated for graininess and pressure desensitization using green light (G). As for the graininess, the aperture scanning area is 250 μm when the density is Dmin + 0.5
^It was shown by the relative value of the standard deviation (RMS value) of the fluctuation of the concentration value caused by scanning with the microdensitometer of No. ² .
The smaller the RMS value, the better the graininess, and the more effective it is. The RMS value of Sample-103 is shown as a value of 100, and the larger the value relative to 100, the worse the deterioration.

Pressure desensitization is 23 ° C, 55% (relative humidity)
Under a condition of, using a scratch strength tester (manufactured by Shinto Kagaku Co., Ltd.), a needle having a tip radius of curvature of 0.025 μm is scanned at a constant speed with a load of 5 g, and then exposed and developed. Dmin
Concentration when no load is applied at +0.4 concentration (D)
The density difference (ΔD) was measured and the value was shown as (ΔD / D) (the larger the value, the more deteriorated).
The obtained results are shown in Table 6.

[0126]

Table 6 Sample name Graininess Pressure desensitization (ΔD / D) 101 (Comparison) 198 0.05 102 (Comparison) 96 0.12 103 (Invention) 100 0.02 104 (Invention) 102 0.03

As is clear from Table 6, the samples 103 and 104 containing the silver halide grains according to the present invention are monodisperse,
It can be seen that the graininess and pressure resistance are excellent. On the other hand, the sample 101 using the comparative milk Em-1 has excellent pressure resistance, but the particle size distribution of the particles is deteriorated, and thus the granularity is significantly deteriorated. Although the sample 102 using the comparative emulsion Em-2 has excellent graininess, the pressure resistance is deteriorated because the desalting step is performed between the low-iodity inner nucleus and the high-iodity layer. ing.

[0128]

INDUSTRIAL APPLICABILITY According to the present invention, a seed crystal has a core made of silver iodobromide containing less than 7 mol% of silver iodide, and a silver iodide content higher than that of silver iodobromide in the core is provided outside the core. It is possible to provide a silver halide emulsion excellent in graininess and pressure resistance by being composed of a shell of silver iodobromide and having the seed crystal monodispersed.

Claims (2)

[Claims] 1. A silver halide emulsion containing silver halide grains consisting essentially of silver iodobromide obtained by growing seed crystals that have undergone a washing step, wherein the seed crystals are silver iodide 7. A core composed of silver iodobromide containing less than 1 mol% and a shell composed of silver iodobromide having a higher silver iodide content than the core silver iodobromide outside the core; A silver halide emulsion characterized by being monodisperse. 2. The halogen according to claim 1, wherein 60% or more in terms of the number ratio of the total number of grains is composed of twin grains having two twin planes parallel to the main plane. Silver halide emulsion.