EP0564878A2

EP0564878A2 - Silver halide photographic emulsion

Info

Publication number: EP0564878A2
Application number: EP19930104593
Authority: EP
Inventors: Toshiya Kondo
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 1992-04-06
Filing date: 1993-03-20
Publication date: 1993-10-13
Also published as: JPH05289214A

Abstract

Disclosed is a silver halide photographic emulsion comprising silver halide grains and a protective-colloid-containing aqueous solution, wherein the silver halide grains are formed by adding a halogen element, after the initiation of the growth of the silver halide grains, to the protective-colloid-containing aqueous solution where the silver halide grains are being grown.
The silver halide photographic emulsion can give a silver halide photographic light-sensitive materials high in sensitivity, excellent in graininess and satisfactory in preservability.

Description

FIELD OF THE INVENTION

The present invention relates to a silver halide emulsion used in the manufacture of silver halide photographic light-sensitive materials, particularly to a a silver halide emulsion used in the manufacture of silver halide photographic light-sensitive materials improved in sensitivity, graininess and preservability.

BACKGROUND OF THE INVENTION

With the wide spread of photographing apparatus such as cameras, photographing with silver halide photographic light-sensitive materials has become more popular and prevalent. And, as a result, a higher sensitivity and a higher image quality are increasingly demanded of silver halide photographic materials.
For silver halide photographic light-sensitive materials, one of the controlling factors in obtaining a high sensitivity and a high image quality is silver halide grains and, therefore, many studies have so far been made in the photographic industry for the development of silver halide grains high in sensitivity and thereby capable of providing images of high quality.
However, reducing the size of silver halide grains, which is generally practiced for the improvement of image quality, is liable to lower the sensitivity. Accordingly, there is a limit in obtaining a high sensitivity and a high image quality concurrently.
There have been studied techniques to raise the sensitivity/size ratio per silver halide grain for the purpose of realizing a much higher sensitivity and a much better image quality, and, as an outcome of such studies, techniques which use tabular silver halide grains are disclosed, for example, in Japanese Pat. O.P.I. Pub. Nos. 111935/1983, 111936/1983, 111937/1983, 113927/1983 and 99433/1984. When compared with regular silver halide grains comprising octahedrons, tetradecahedrons or hexahedrons, these tabular silver halide grains have a larger surface area per unit volume and, thereby, can adsorb more sensitizing dyes on their surface to provide a higher sensitivity.
In addition, Japanese Pat. O.P.I. Pub. No. 92942/1988 discloses a technique providing silver iodide rich cores inside of tabular silver halide grains, Japanese Pat. O.P.I. Pub. No. 151618/1988 discloses a technique using hexagonal, tabular silver halide grains, and Japanese Pat. O.P.I. Pub. No. 163451/1988 discloses a technique using tabular silver halide grains in each of which the ratio of the longest distance between twin faces to the thickness of grain is not less than 5; these techniques are described to be effective in improving sensitivity and graininess.
Further, Japanese Pat. O.P.I. Pub. No. 106746/1988 describes a technique using tabular silver halide grains substantially having layer structure parallel to the major crystal planes facing each other, and Japanese Pat. O.P.I. Pub. No. 279237/1989 describes the use of tabular silver halide grains having layer structure parallel to the major crystal planes facing each other, and the average silver iodide content in the outermost layer is higher than the average silver iodide content of the whole grain by 1 mol% or more. Besides the above, Japanese Pat. O.P.I. Pub. No. 183644/1989 discloses the use of tabular grains comprising a silver iodide containing silver halide having a perfectly uniform silver iodide distribution.
However, these conventional techniques have a limit in providing both high sensitivity and high image quality; therefore, these are not necessarily sufficient in providing a high sensitivity and a high image quality concurrently, which are required of recent light-sensitive materials. Accordingly, there has been demanded a better technique to solve the problem.

SUMMARY OF THE INVENTION

The object of the invention is to provide a silver halide photographic emulsion which can give silver halide photographic light-sensitive materials high in sensitivity, excellent in graininess and satisfactory in preservability.
The object of the invention is attained by satisfying one of the following constituent requirements:

(1) A silver halide photographic emulsion comprising silver halide grains and a protective-colloid-containing aqueous solution, wherein the silver halide grains are formed by adding a halogen element, after the initiation of the substantial growth of the silver halide grains, to the protective-colloid-containing aqueous solution in which the silver halide grains are being grown.
(2) A silver halide photographic emulsion as stated in the above paragraph (1), wherein the halogen element is iodine.
(3) A silver halide photographic emulsion as stated in the above paragraph (1) or (2), wherein the substantial growth of silver halide grains is made by adding the halogen element before completing 50% of the growth in silver halide amount.
(4) A silver halide photographic emulsion as stated in the above paragraph (2), wherein the halogen element is added during the formation of silver halide phases containing 5% or more silver iodide.
(5) A silver halide photographic emulsion as stated in the above paragraph (3), wherein the halogen element is added during the formation of silver halide phases containing 5% or more silver iodide.
(6) A silver halide photographic emulsion as stated in the above paragraph (2), wherein the addition of the halogen element is made in two or more parts.
(7) A silver halide photographic emulsion as stated in the above paragraph (2), wherein the addition of the halogen element is made continuously.

DETAILED DESCRIPTION OF TEE PREFERRED EMBODIMENT

The present inventors have made a close study and found that the sensitivity, graininess and preservability of silver halide photographic light-sensitive materials can be significantly improved by oxidizing silver specks present in silver halide grains.
As oxidizing agents to oxidize such silver specks, a variety of organic compounds and inorganic compounds are known; but, there has been no literature or material which suggests a pronounced effect given by the halogen element used in the invention.
The halogen element produces the effect of the invention by being added, after the substantial growth of silver halide grains is initiated, to a protective-colloid-containing aqueous solution in which these silver halide grains are being grown. It is also found that a larger effect is produced by carrying out the addition while silver halide phases or silver iodide rich phases are formed in silver halide grains, and that a much larger effect is obtained by carrying out the addition while silver iodide rich phases are formed in silver halide grains.
Though silver specks are thought to be present everywhere of a silver halide phase or a silver iodide rich phase in a silver halide grain, the effect becomes larger when the addition of the halogen element is made in two or more parts during silver grain formation, and the effect becomes much larger when the addition of the halogen element is made continuously during silver grain formation.
The silver halide emulsion of the invention can use as silver halide any of those employed in conventional silver halide emulsions, such as silver bromide, silver iodobromide, silver iodochloride, silver chlorobromide, silver chloroiodobromide and silver chloride. But use of silver bromide, silver iodobromide or silver chloroiodobromide is particularly preferred.
The silver halide grains contained in the silver halide emulsion of the invention may be either grains with which latent images are mainly formed on the surface or grains with which latents images are mainly formed internally.
The silver halide grains may have a regular crystal form such as a cubic, octahedral or tetradecahedral one, or an irregular crystal form such as spherical or tabular one. These grains may have any (100) face to (111) face ratio. Further, there may also be used grains whose crystal form is a combination of the above ones or a mixture of grains different in crystal forms. Preferred among them are tabular silver halide grains having two parallel twin planes facing each other.
The term "twin crystal grains" is intended here to include silver halide crystal grains each having one or more twin planes; the classification of twin crystal forms is discussed in detail by Klein and Moiser in "Photographishe Korrespondenz", Vol.99, P.99 and ibid., Vol.100, P.57.
When tabular silver halide grains are used in the invention, the mean value of thickness-to-grain size ratios of these tabular grains (average aspect ratio) is preferably from 1.3 to less than 5.0, more preferably from 1.5 to less than 4.5 and most preferably from 2.0 to less than 4.5. This mean value is obtained by averaging thickness-to-grain size ratios of all the tabular grains present.
The grain size of a silver halide grain of the invention, which is indicated by the diameter of a circle corresponding to the projected area of the silver halide grain (the diameter of a circle having the same projected area as the the silver halide grain), is preferably 0.1 to 5.0 µm, more preferably 0.2 to 4.0 µm and most preferably 0.3 to 3.0 µm.
The silver halide emulsion of the invention may use any type of emulsions including polydispersed emulsions having a broad grain size distribution and monodispersed emulsions having a narrow grain size distribution, but monodispersed emulsions are preferred.
In such monodispersed silver halide grains, the weight of grains having the grain sizes within the range of ±20% around the average grain size r is preferably not less than 60%, more preferably not less than 70% and most preferably not less than 80% of the total weight of the silver halide grains.
This average grain size r is defined as grain size ri which gives a maximum value for the product of frequency ni of grains having grain size ri and ri³, or ni × ri³ (three significant figures, the last figure is rounded to the nearest whole number). The term "grain size" means the diameter of a circle converted in the same area from a silver halide grain's projected image.
Such a grain size can be obtained by photographing a grain with an electronic microscope at magnifications of 10,000 to 70,000 and measuring the diameter or the projected area of the grain image on the print (at least 1,000 grains selected at random are subjected to measurement in obtaining an average grain size).
When the extent of a grain size distribution is defined by

a highly monodispersed emulsion preferred in the invention has an extent of distribution not more than 20%, preferably not more than 15%. In the equation, the average grain size and the standard deviation are obtained from grain size ri defined above.
When silver iodobromide is used in embodying the invention, the amount of silver iodide contained therein is preferably not less than 2 mol% to not more than 15 mol%, more preferably not less than 3 mol% to not more than 12 mol% and most preferably not less than 4 mol% to not more than 10 mol%, as an average silver iodide content in the total silver halide grains.
The silver halide grains contained in the silver halide emulsion of the invention are preferably the so-called core/shell type grains in which silver iodide is concentrated at the inner part of grains.
Such core/shell type grains are each composed of a core and a shell to cover the core, and the shell comprises one or more layers. It is preferable that the silver iodide content in the core and that in the shell be different from each other; in a particularly preferred embodiment of the invention, the core is formed with the highest silver iodide content.
The silver iodide content of the core is preferably not less than 10 mol% to not more than maximum solid solubility, more preferably not less than 20 mol% to not more than the maximum solid solubility and, most preferably not less than 25 mol% to not more than the maximum solid solubility. The silver iodide content of the outermost shell, a shell which forms the surface layer, is preferably not more than 5 mol%, especially 0 to 2 mol%. The ratio of the core is preferably 2 to 60% by volume, especially 5 to 50% by volume of the whole grain.
The term, "The maximum solid solubility", herein stated is the maximum iodide content (mol%) which is capable to form solid solution in silver halide crystals, and is detailed in T.H. James et al., "The Theory of Photographic Process" Forth Edition, Macmillan Publishing Co. Inc., P4 and is defined by following formula in the case of silver iodobromide

$= 34.5 + 0.165 (t-25)$

wherein t is the temperature of precipitation in C°.
The silver halide grains contained in the silver halide photographic emulsion of invention are prepared by placing a protective-colloid-containing aqueous solution and seed grains in a reaction vessel and then growing the seed grains into crystals through supply of silver ions and halogen ions, or silver halide fine grains, as occasion demands. These seed grains can be prepared by the single-jet method or the controlled double-jet method, each of which is well known to those skilled in the art.
The composition of the seed grains can be arbitrarily selected from silver bromide, silver iodide, silver chloride, silver iodobromide, silver chlorobromide, silver chloroiodide and silver chloroiodobromide. But silver bromide and silver iodobromide are preferred.
The seed grains used in the invention may be those having a regular crystal form such as cubes, octahedrons or tetradecahedrons, or those having an irregular crystal form such as spheres or plates. These grains may have any {100} face-to-{111} face ratio. There may also be used grains having a combined crystal form or a mixture of grains of various crystal forms, but the monodispersed spherical seed grains disclosed in Japanese Pat. Appl. No. 408178/1990 can be advantageously used.
In forming the silver halide photographic emulsion of the invention, there can be used various methods known to those skilled in the art; that is, the single-jet method, the double-jet method and the triple-jet method can be used in an arbitrary combination. Further, there can be jointly used a method for controlling the pAg and pH of a liquor phase in which silver halide is formed, in accordance with the growth rate of silver halide grains.
The silver halide photographic emulsion of the invention can be produced by any of the acidic method, the neutral method and the ammoniacal method.
In producing the silver halide photographic emulsion of the invention, halide ions and silver ions may be added simultaneously, or one of the two types of ions may be added to a system where the other is present in advance. The silver halide grains may also be grown by adding sequentially or simultaneously halide ions and silver ions with the pH and pAg of the reaction liquor controlled properly, while paying attention to the critical growth rate of the silver halide grains. Or the silver halide composition of the grains may be changed by applying the conversion method in an arbitrary process of silver halide formation. Further, halide ions and silver ions may be added in the mixing vessel in the form of silver halide fine grains.
The silver halide photographic emulsion of the invention is characterized in that silver halide grains contained therein are formed by adding a halogen element to a protective-colloid-containing aqueous solution, in which the silver halide grains are grown, after the initiation of the substantial growth of the silver halide grains.
In the invention, a protective-colloid-containing aqueous solution means a system comprising a protective colloid formed of gelatin, or of another hydrophilic-colloid-forming material, in an aqueous solution. Preferred is an aqueous solution containing a colloidal protective gelatin.
As a halogen element used in embodying the invention, bromine and iodine are useful; of them, iodine is preferred.
In the invention, it is preferable that the substantial growth of silver halide grains be made by adding a halogen element before completing the growth by 50% in silver halide amount. The term "50% in silver halide amount" means 50% of the total amount of the silver halide formed in a protective-colloid-containing aqueous solution, in which the silver halide grains of the invention are grown during the period between start and end of the substantial growth of the grains. Preferably, the addition of the halogen element is made before completing 45% of the growth, especially before completing 40% of the growth.
In the embodiment of the invention, the halogen element is added during the formation of silver halide phases having a silver iodide content not less than 5 mol%, preferably during the formation of silver halide phases having a silver iodide content not less than 10 mol% to not more than the maximum solid solubility, especially not less than 15 mol% to not more than the maximum solid solubility.
In a favorable embodiment of the invention, the halogen element is added before completing 50% of the substantial growth of silver halide grains in silver halide amount and during the formation of silver halide phases having a silver iodide content not less than 5 mol%. Preferably, the halogen element is added before completing 45% of the substantial growth of silver halide grains in silver halide amount and during the formation of silver halide phases having a silver iodide content not less than 10 mol% to not more than the maximum solid solubility. Particularly preferred is to add the halogen element before completing 40% of the substantial growth of silver halide grains in silver halide amount and during the formation of silver halide phases having a silver iodide content not less than 15 mol% to not more than the maximum solid solubility.
In the invention, the addition of the halogen element means to supply the halogen element, or a solution dissolving the halogen element, to a protective-colloid-containing aqueous solution in which silver halide grains used in the silver halide emulsion are grown.
The halide element can be added according to the techniques used in the industry which add additives to a silver halide emulsion; that is, the addition is made, for example, by dissolving the halogen element in a suitable organic solvent represented by ethanol or in water beforehand.
When iodine is used as halogen element, it is preferable to use it in the form of methanol solution.
To add the halogen element to a protective-colloid-containing aqueous solution, the halogen element or a solution dissolving the halogen element is introduced in to the aqueous solution with a funnel or a pump.
In the invention, the halogen element may be added to a protective-colloid-containing aqueous solution while halide ions and silver ions, or silver halide fine grains, are being fed thereto. Or the halide element or a solution thereof may be added in advance to an aqueous solution containing halide ions, an aqueous solution containing silver ions or an aqueous solution containing silver halide fine grains.
In a preferred embodiment of the invention, the halogen element is added in two or more parts. In a particularly preferred embodiment, the addition is made continuously. In the case of continuous addition, it may be a constant rate addition, or it may be carried out using an arbitrary function between addition rate and time.
The addition amount of the halogen element is usually 10⁻⁸ to 10⁻¹ mol, preferably 10⁻⁷ to 5 × 10⁻² mol and especially 10⁻⁶ to 10⁻² mol per mol of silver halide grains of the invention.
The term "during formation of silver halide grains", which is used in connection with the silver halide emulsion of the invention, means a silver halide emulsion manufacturing process from the initiation of the nuclei formation of silver halide grains, after feeding halide ions and silver ions as a water-soluble alkali halide and a water-soluble silver salt or as silver halide fine grains to a protective-colloid-containing aqueous solution where the silver halide grains are being grown, to the termination of the growth of the silver halide grains; therefore, this does not include desalting of the grown silver halide grains and the succeeding processes of silver halide emulsion manufacture.
The term "during formation of silver halide grains", which is used in connection with the growth of silver halide grains to be contained in the silver halide emulsion of the invention from seed grains, means the silver halide emulsion manufacturing process from the initiation of the growth of silver halide grains due to deposition of silver halide on the seed grains to the termination of the growth of the silver halide grains; therefore, this does not include desalting of the grown silver halide grains and the succeeding processes of silver halide emulsion manufacture.
The term "the initiation of the substantial growth of silver halide grains" used here means the initiation of the deposition of silver halide on seed grains due to silver ions and halide ions fed to the seed grains from aqueous solutions respectively containing silver ions and halide ions or silver halide fine grains.
The term "after the initiation of the substantial growth of silver halide grains" used in the invention means a silver halide emulsion manufacturing process from the initiation of the substantial growth of silver halide grains to the termination of the growth of the silver halide grains; therefore, this does not include desalting of the grown silver halide grains and the succeeding processes of silver halide emulsion manufacture.
In the manufacture of the silver halide emulsion of the invention, there may be present in the reaction system a conventional silver halide solvent such as ammonia, thio ether or thiourea.
The silver halide grains contained in the silver halide emulsion of the invention may be made to contain metal elements inside and/or on the surface of the grains by adding, in the course of grain formation and/or grain growth, metal ions using at least one of cadmium salts, zinc salts, lead salts, thallium salts, iridium salts (including complex salts), rhodium salts (including complex salts) and iron salts (including complex salts). These grains may also be made to have reduction-sensitized specks inside or on the surface of the grains by being subjected to a suitable reducing atmosphere.
The silver halide photographic emulsion of the invention may be subjected to desalting after completing the growth of grains for removing useless soluble salts, or it may be used with such soluble salts unremoved. To remove such salts, there can be used the methods described in Research Disclosure (hereinafter abbreviated as RD), No. 17643, section II.
In the manufacture of the silver halide photographic emulsion of the invention, conditions other than the above can be appropriately selected by referring to the methods described in Japanese Pat. O.P.I. Pub. Nos. 6643/1986, 14630/1986, 112142/1986, 157024/1987, 18556/1987, 92942/1988, 151618/1988, 163451/1988, 220238/1988 and 311244/1988.
The silver halide photographic emulsion of the invention can be advantageously used in silver halide color photographic light-sensitive materials.

When used in color photographic light-sensitive materials, the silver halide emulsion of the invention is subjected to physical ripening, chemical ripening and spectral sensitization before it is used. Additives usable in these processes can be seen in Research Disclosure Nos. 17643, 18716 and 308119 (hereinafter abbreviated as RD17643, RD18716 and RD308119, respectively). Locations of relevant descriptions are as follows:

Item	Page, Section of RD308119	Page of RD17643	Page of RD18716
Chemical sensitizer	996 III-A	23	648
Spectral sensitizer	996 IV-A-A,B C,D,H,I,J	23-24	648-9
Supersensitizer	996 IV-A-E,J	23-24	648-9
Antifoggant	998 VI	24-25	649
Stabilizer	998 VI	24-25	649

Conventional photographic additives usable in making color photographic light-sensitive materials using the silver halide photographic emulsion of the invention can also be found in the above Research Disclosure. Locations of relevant descriptions are as follows:

Item	Page, Section of RD308119	Page of RD17643	Page of RD18716
Anticolor-mixing agent	1002 VII-I	25	650
Dye image stabilizer	1001 VII-J	25	-
Whitening agent	998 V	24	-
UV absorbent	1003 VIII-C XIII-C	25-26	-
Light absorbent	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
Lubricant	1006 XII	27	650
Surfactant,coating aid	1005 XI	26-27	650
Matting agent	1007 XVI	-	-
Developing agent	1011 XX-B	-	-
(contained in light-sensitive materials)

A variety of couplers can be used in making color photographic light-sensitive materials using the silver halide photographic emulsion of the invention, typical examples thereof can be seen in the above Research Disclosures. Locations of relevant descriptions are as follows:

Item	Page, Section of RD308119	Section of RD17643
Yellow Coupler	1001 VII-D	VII C-G
Magenta coupler	1001 VII-D	VII C-G
Cyan coupler	1001 VII-D	VII C-G
Colored coupler	1002 VII-G	VII G
DIR coupler	1001 VII-F	VII F
BAR coupler	1002 VII-F	-
Other useful group releasing couple	1001 VII-F	-
Alkali soluble coupler	1001 VII-E	-

The foregoing additives can be incorporated in the silver halide emulsion of the invention according to the dispersion method and the like described in section XIV of RD308119.
In the manufacture of color photographic light-sensitive materials using the silver halide emulsion of the invention, there can be used the supports described on page 28 of RD17643, pages 647-8 of RD18716 and in section XVII of RD308119.
The color photographic light-sensitive material using the silver halide emulsion of the invention may have an auxiliary layer such a filter layer or an intermediate layer described in section VII-K of the above RD 308119.
The color photographic light-sensitive material using the silver halide emulsion of the invention may take various layer configurations such as conventional layer order, inverted layer order and unit layer structure.
The silver halide photographic emulsion of the invention can be advantageously used in various color photographic light-sensitive materials represented by color negative films for popular use and for movies, color reversal films for slides or for television, color paper, color positive films and color reversal paper.
The color photographic light-sensitive material using the silver halide emulsion of the invention can be processed by the usual methods described on pages 28-29 of RD17643, page 615, of RD18716 and in section XIX of RD308119.

EXAMPLES

The presents invention is hereunder described in detail by referring to preferable examples. However, the scope of the invention is not limited to there examples.

Example 1

(1) Preparation of Spherical Seed Emulsion (Em-1)

On referring to Japanese Pat. Appl. No.408178/1990, a monodispersed spherical seed emulsion, Em-1, was prepared according to the following method.

Solution J

Ossein gelatin	80 g
Potassium bromide	47.4 g
Sodium polyisopropylene-polyethyleneoxy disuccinate 10% methanol solution	20 ml
Water was added to	8000 ml

Solution K

Sodium nitrate 1200 g

Water was added to 1600 ml

Solution L

Ossein gelatin	32.2 g
Potassium bromide	840 g
Water was added to	1600 ml

Solution M

Aqueous ammonia 470 ml
While vigorously stirring solution J at 40°C, Solutions K and L were added thereto by the double-jet method in 11 minutes to form nuclei. During the addition the pBr was kept at 1.60. Then, the temperature was lowered to 30°C in 12 minutes, followed by an 18-minute ripening. Subsequently, solution M was added in 1 minute, followed by a 5-minute ripening at a KBr concentration of 0.07 mol/l and an ammonia concentration of 0.63 mol/l.
After the ripening, the pH was adjusted to 6.0, and desalting was carried out according to the usual method. Observations with an electron microscope proved that the resulting seed emulsion comprised spherical grains having two twin planes parallel to each other and an average grain size of 0.318 µm.

(2) Preparation of Comparative Emulsion (Em-2)

A comparative emulsion, Em-2, was prepared by use of the following eight solutions.

Solution A

Ossein gelatin	268.2 g
Deionized water	4000 ml
Sodium polyisopropylene-polyethyleneoxy disuccinate 10% methanol solution	1.5 ml
28 wt% Aqueous ammonia	528.0 ml
56 wt% Aqueous acetic acid	795.0 ml
Deionized water was added to make	5390.0 ml

Solution B

3.5 N Aqueous solution of ammoniacal silver nitrate (adjusted to pH 9.0 with ammonium nitrate)

Solution C

3.5 N aqueous potassium bromide solution containing 4.0 wt% gelatin

Solution D

Fine grain emulsion comprising 3 wt% gelatin and silver iodide fine grains (average grain size: 0.05 µm) 2.39 mol
This emulsion was prepared by adding, in 10 minutes, 2000 ml each of two aqueous solutions respectively containing 7.06 mol of silver nitrate and 7.06 mol of potassium iodide to 5000 ml of 6 wt% gelatin solution containing 0.06 mol of potassium iodide. During the formation of fine grains, the pH was controlled at 2.0 and the temperature at 40°C and, after the formation of grains, the pH was adjusted to 6.0 with a potassium carbonate aqueous solution.

Solution E

Fine grain emulsion comprising silver iodobromide grains (silver iodide content: 1 mol%, average grain size: 0.04 µm) 6.24 mol

This was prepared in the same manner as solution D except that the temperature was controlled at 30°C during the formation of fine grains.

Solution F

1.75 N potassium bromide Aqueous solution necessary amount

Solution G

56 wt% Aqueous acetic acid necessary amount

Solution H

Seed emulsion (Em-1) 0.286 mol
After adding solution H to solution A kept at 70°C in a reaction vessel, solutions B, C and D were added thereto by the triple-jet method in of 163 minutes, followed by addition of solution E for 12 minutes at a constant rate.
In order to avoid polydispersion due to formation of fine grains other than seed grains being grown and the Ostwald ripening, the addition of solutions B and C was made while changing the addition rate correspondingly to the critical growth rate as a function of time.
The ratio of the addition rate of solution D to that of solution B was set so as to form silver halide phases having silver iodide contents mol% shown in Table 1, so that a multilayered core/shell-type silver halide emulsion was obtained.
Further, during the growth of grains, the pAg and pH were controlled as shown in Table 1. Measurements of the pAg and pH were made according to the usual method using a silver sulfide electrode and a glass electrode.
After the formation of grains, desalting was carried out according to the method described in Japanese Pat. Appl. No. 41314/1991. Then, gelatin was added to redispers the grains, and the pH was adjusted to 5.80 and the pAg to 8.06 at 40°C.

From a scanning electron micrograph, the resulting emulsion was confirmed to be a monodispersed emulsion comprising octahedral twinned crystal grains having an average grain size of 1.0 µm and a grain size distribution extent of 10.3%.

Table 1

	Addition Time (min)	Grain size (µm)	Silver Iodide Content (mol%)	pH	pAg
Intermediate Layer	0.0	0.318	10.3	7.2	7.8
	23.1	0.432	10.3	7.2	7.8
	38.0	0.495	10.3	7.2	7.8
Core Portion	50.1	0.538	30.0	7.2	7.8
	82.6	0.657	30.0	7.2	7.8
	82.6	0.657	30.0	6.5	9.4
Shell Portion	112.7	0.706	10.3	6.5	9.4
	122.0	0.723	10.3	6.5	9.4
	141.6	0.781	7.7	6.5	9.4
	141.6	0.781	0.0	6.5	9.4
	163.0	0.925	0.0	6.5	9.7

(3) Preparation of Emulsion of the Invention (Em-3)

An emulsion of the invention, Em-3, was prepared in the same manner as the comparative emulsion, Em-2, except that the following solution I-1 was added to solution A in 30 second, at a constant rate, 50.1 minutes after starting addition of solutions B, C and D. The resulting emulsion comprised monodispersed octahedral twinned crystal grains having an average grain size of 1.0 µm and a grain size distribution extent of 10.9%.

Solution I-1

Aqueous solution containing bormine of 0.0003 mols per mol of silver halide grains of emulsion (Em-2) 50.0 ml

(4) Preparation of Emulsion of the Invention (Em-4)

An emulsion of the invention, Em-4, was prepared in the same manner as the comparative emulsion, Em-2, except that the following solution I-2 was added to solution A in 30 seconds, at a constant rate, 50.1 minutes after starting addition of solutions B, C and D. The resulting emulsion comprised monodispersed octahedral twinned crystal grains having an average grain size of 1.0 µm and a grain size distribution extent of 10.6%.

Solution I-2

Methanol solution containing iodine of 0.0003 mols per mol of silver halide grains of emulsion (Em-2) 50.0 ml

(5) Preparation of Emulsion of the Invention (Em-5)

An emulsion of the invention, Em-5, was prepared in the same manner as the comparative emulsion, Em-2, except that the following solution I-3 was added to solution A in 30 seconds, at a constant rate, 50.1 minutes after starting addition of solutions B, C and D. The resulting emulsion comprised monodispersed octahedral twinned crystal grains having an average grain size of 1.0 µm and a grain size distribution extent of 11.4%.

Solution I-3

Methanol solution containing iodine of 0.0006 mols per mol of silver halide grains of emulsion (Em-2) 50.0 ml

(6) Preparation of Emulsion of the Invention (Em-6)

An emulsion of the invention, Em-6, was prepared in the same manner as the comparative emulsion, Em-2, except that the following solution I-4 was added to solution A in 30 seconds, at a constant rate, 23.1 minutes after starting addition of solutions B, C and D. The resulting emulsion comprised monodispersed octahedral twinned crystal grains having an average grain size of 1.0 µm and a grain size distribution extent of 11.5%.

Solution I-4

(7) Preparation of Emulsion of the Invention (Em-7)

An emulsion of the invention, Em-7, was prepared in the same manner as the comparative emulsion, Em-2, except that the following solution I-5 was added to solution A in 30 seconds, at a constant rate, 122.0 minutes after starting addition of solutions B, C and D. The resulting emulsion comprised monodispersed octahedral twinned crystal grains having an average grain size of 1.0 µm and a grain size distribution extent of 11.0%.

Solution I-5

(8) Preparation of Emulsion of the Invention (Em-8)

An emulsion of the invention, Em-8, was prepared in the same manner as the comparative emulsion, Em-2, except that the following solution I-6 was added to solution A in 30 seconds, at a constant rate, 163.0 minutes after starting addition of solutions B, C and D. The resulting emulsion comprised monodispersed octahedral twinned crystal grains having an average grain size of 1.0 µm and a grain size distribution extent of 10.5%.

Solution I-6

Methanol solution containing iodine of 0.0003 mols per mol of silver halide grains of emulsion (Em-2) 50.0 ml
The characteristics of silver halide emulsions Em-2 to Em-8 are shown in Table 2.
Silver halide emulsions Em-2 to Em-8 were each subjected to optimum chemical sensitization. These were used in the following light-sensitive material recipe with the denotation of (emulsion A).
Multilayered color photographic light-sensitive materials Nos.11 to 18 were prepared by forming the following layers in order on a triacetylcellulose film support.

Addition amounts are in grams per square meter unless otherwise stated. Amounts of silver halide and colloidal silver are shown in silver equivalent, and amounts of sensitizing dyes are shown in moles per mole of silver.

1st layer: antihalation layer
Black colloidal silver	0.16
UV absorbent UV-1	0.20
High boiling solvent Oil-1	0.16
Gelatin	1.23

2nd layer: intermediate layer
Compound SC-1	0.15
High boiling solvent Oil-2	0.17
Gelatin	1.27

3rd layer: low-speed red-sensitive layer
Silver iodobromide emulsion (average grain size: 0.38 µm, silver iodide content: 8.0 mol%)	0.50
Silver iodobromide emulsion (average grain size: 0.27 µm, silver iodide content: 2.0 mol%)	0.21
Sensitizing dye SD-1	2.8 × 10⁻⁴
Sensitizing dye SD-2	1.9 × 10⁻⁴
Sensitizing dye SD-3	1.9 × 10⁻⁵
Sensitizing dye SD-4	1.0 × 10⁻⁴
Cyan coupler C-1	0.48
Cyan coupler C-2	0.14
Colored cyan coupler CC-1	0.021
DIR compound D-1	0.020
High boiling solvent Oil-1	0.53
Gelatin	1.30

4th layer: medium-speed red-sensitive layer
Silver iodobromide emulsion (average grain size: 0.52 µm, silver iodide content: 8.0 mol%)	0.62
Silver iodobromide emulsion (average grain size: 0.38 µm, silver iodide content: 8.0 mol%)	0.27
Sensitizing dye SD-1	2.3 × 10⁻⁴
Sensitizing dye SD-2	1.2 × 10⁻⁴
Sensitizing dye SD-3	1.6 × 10⁻⁵
Sensitizing dye SD-4	1.2 × 10⁻⁴
Cyan coupler C-1	0.15
Cyan coupler C-2	0.18
Colored cyan coupler CC-1	0.030
DIR compound D-1	0.013
High boiling solvent Oil-1	0.30
Gelatin	0.93

5th layer: high-speed red-sensitive layer
Silver iodobromide emulsion (emulsion A)	1.27
Sensitizing dye SD-1	1.3 × 10⁻⁴
Sensitizing dye SD-2	1.3 × 10⁻⁴
Sensitizing dye SD-3	1.6 × 10⁻⁵
Cyan coupler C-2	0.12
Colored cyan coupler CC-1	0.013
High boiling solvent Oil-1	0.14
Gelatin	0.91

6th layer: intermediate layer
Compound SC-1	0.09
High boiling solvent Oil-2	0.11
Gelatin	0.80

7th layer: low-speed green-sensitive layer
Silver iodobromide emulsion (average grain size: 0.38 µm, silver iodide content: 8.0 mol%)	0.61
Silver iodobromide emulsion (average grain size: 0.27 µm, silver iodide content: 2.0 mol%)	0.20
Sensitizing dye SD-4	7.5 × 10⁻⁵
Sensitizing dye SD-5	6.6 × 10⁻⁴
Magenta coupler M-1	0.18
Magenta coupler M-2	0.44
Colored magenta coupler CM-1	0.12
High boiling solvent Oil-2	0.75
Gelatin	1.95

8th layer: medium-speed green-sensitive layer
Silver iodobromide emulsion (average grain size: 0.59 µm, silver iodide content: 2.0 mol%)	0.87
Sensitizing dye SD-6	2.4 × 10⁻⁴
Sensitizing dye SD-7	2.4 × 10⁻⁴
Magenta coupler M-1	0.058
Magenta coupler M-2	0.13
Colored magenta coupler CM-1	0.070
DIR compound D-2	0.025
DIR compound D-3	0.002
High boiling solvent Oil-2	0.50
Gelatin	1.00

9th layer: high-speed green-sensitive layer
Silver iodobromide emulsion (emulsion A)	1.27
Sensitizing dye SD-6	1.4 × 10⁻⁴
Sensitizing dye SD-7	1.4 × 10⁻⁴
Magenta coupler M-2	0.084
Magenta coupler M-3	0.064
Colored magenta coupler CM-1	0.012
High boiling solvent Oil-1	0.27
High boiling solvent Oil-2	0.012
Gelatin	1.00

10th layer: yellow filter layer
Yellow colloidal silver	0.08
Antistain agent SC-2	0.15
Formalin scavenger HS-1	0.20
High boiling solvent Oil-2	0.19
Gelatin	1.10

11th layer: intermediate layer
Formalin scavenger HS-1	0.20
Gelatin	0.60

12th layer: low-speed blue-sensitive layer
Silver iodobromide emulsion (average grain size: 0.38 µm, silver iodide content: 8.0 mol%)	0.22
Silver iodobromide emulsion (average grain size: 0.27 µm, silver iodide content: 2.0 mol%)	0.03
Sensitizing dye SD-8	4.9 × 10⁻⁴
Yellow coupler Y-1	0.75
DIR compound D-1	0.010
High boiling solvent Oil-2	0.30
Gelatin	1.20

13th layer: medium-speed blue-sensitive layer
Silver iodobromide emulsion (average grain size: 0.59 µm, silver iodide content: 8.0 mol%)	0.30
Sensitizing dye SD-8	1.6 × 10⁻⁴
Sensitizing dye SD-9	7.2 × 10⁻⁵
Yellow coupler Y-1	0.10
DIR compound D-1	0.010
High boiling solvent Oil-2	0.046
Gelatin	0.47

14th layer: high-speed blue-sensitive layer
Silver iodobromide emulsion (emulsion A)	0.85
Sensitizing dye SD-8	7.3 × 10⁻⁵
Sensitizing dye SD-9	2.8 × 10⁻⁵
Yellow coupler Y-1	0.11
High boiling solvent Oil-2	0.046
Gelatin	0.80

15th layer: 1st protective layer
Silver iodobromide emulsion (average grain size: 0.08 µm, silver iodide content: 1.0 mol%)	0.40
UV absorbent UV-1	0.065
UV absorbent UV-2	0.10
High boiling solvent Oil-1	0.07
High boiling solvent Oil-3	0.07
Formalin scavenger HS-1	0.40
Gelatin	1.31

16th layer: 2nd protective layer
Alkali soluble matting agent (average particle size: 2 µm)	0.15
Polymethyl methacrylate (average particle size: 3 µm)	0.04
Lubricant WAX-1	0.04
Gelatin	0.55

Added besides the above compositions were coating aid Su-1, dispersant Su-2, viscosity regulator, hardeners H-1 and H-2, stabilizer ST-1, antifoggants AF-1 (weight average molecular weight: 10,000) and AF-2 (weight average molecular weight: 1,100,000), and antiseptic DI-1. The addition amount of DI-1 was 9.4 mg/m².
The chemical structures of the compounds used in the above light-sensitive material samples are as follows:

The samples were exposed to white light for sensitometry, processed by the following procedure and then evaluated for sensitivity and RMS graininess.

Process (38°C)

Color developing 3 min, 15 sec,

Bleaching 6 min, 30 sec,

Washing 3 min, 15 sec,

Fixing 6 min, 30 sec,

Washing 3 min, 15 sec,

Stabilizing 1 min, 30 sec,

Drying

The processing solutions used in the respective processes were 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· 1/2sulfate	2.0 g
Anhydrous potassium carbonate	37.5 g
Sodium bromide	1.3 g
Trisodium nitrilotriacetate (monohydrate)	2.5 g
Potassium hydroxide	1.0 g
Water was added to 1 liter, and the pH was adjusted to 10.0.

Bleach
Ammonium ferric ethylenediaminetetracetate	100.0 g
Diammonium ethylenediaminetetracetate	10.0 g
Ammonium bromide	150.0 g
Glacial acetic acid	10.0 g
Water was added to 1 liter, and then the pH was adjusted to 6.0 with aqueous ammonia.

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

Stabilizer
Formalin (37% aqueous solution)	1.5 ml
Koniducks (made by Konica Corp.)	7.5 ml
Water was added to 1 liter.

Table 3 shows the evaluation results of the sensitivity and the RMS graininess of samples 11 to 17 prepared by use of emulsions Em-2 to Em-8, where the relative sensitivity (S) is a relative value of the reciprocal of the exposure necessary to give a density of fog density + 0.1 and expressed by a value relative to the green sensitivity of sample 11 which is set at 100. The RMS value is a value 1000 times the the standard deviation of fluctuations in density found when the density of minimum density + 1.0 was scanned with a microdensitometer having a scanning aperture of 250 µm², and expressed by a value relative to the EMS value of sample 11 which is set at 100.

Table 3

Sample No.	Emulsion No.	Classification	Relative Sensitivity	RMS Value (relative value)
11	Em-2	Comparison	100	100
12	Em-3	Invention	115	91
13	Em-4	Invention	122	81
14	Em-5	Invention	115	78
15	Em-6	Invention	112	87
16	Em-7	Invention	111	93
17	Em-8	Invention	105	95

It will be seen in Table 3 that the sample Nos. 12 to 17 using silver halide emulsions Em-3 to Em-8 of the invention are better than the sample using a comparative emulsion in both relative sensitivity and RMS graininess. Particularly, excellent properties can be obtained when iodide is used as halogen element and added to high silver iodide content phases inside of silver halide grains.

Example 2

Samples Nos. 11 to 17 of multilayered color photographic light-sensitive material were prepared in Example 1 were stored under condition A or condition B specified below and, then, processed and evaluated as in Example 1.

Conditions:

A:: 4 days at 65°C and 30%RH
B:: 4 days at 50°C and 80%RH

The results obtained under condition A are shown in Table 4.

Table 4

Sample No.	Emulsion No.	Classification	Relative Sensitivity	RMS Value (relative value)
11	Em-2	Comparison	100	100
12	Em-3	Invention	113	90
13	Em-4	Invention	119	82
14	Em-5	Invention	114	81
15	Em-6	Invention	110	87
16	Em-7	Invention	108	92
17	Em-8	Invention	105	96

The results obtained under condition B are shown in Table 5.

Table 5

Sample No.	Emulsion No.	Classification	Relative Sensitivity	RMS Value (relative value)
11	Em-2	Comparison	100	100
12	Em-3	Invention	111	91
13	Em-4	Invention	126	80
14	Em-5	Invention	126	82
15	Em-6	Invention	114	85
16	Em-7	Invention	106	89
17	Em-8	Invention	106	92

It can be seen in Tables 4 and 5 that even when stored under condition A or B, the samples 12 to 17 using silver halide emulsions Em-3 to Em-8 of the invention are superior to the sample using a comparative emulsion in both relative sensitivity and RMS graininess. Especially, excellent properties can be obtained when iodine is used as halogen element and added to high silver iodide content phases inside of silver halide grains.

Example 3

(9) Preparation of Monodispersed Spherical Seed Emulsion (Em-9)

A monodispersed spherical seed emulsion was prepared in accordance with the following procedure.

Solution A₁

Ossein gelatin	150 g
Potassium bromide	53.1 g
Potassium iodide	24 g
Water was added to	7200 ml

Solution B₁

Silver nitrate 1800 g

Water was added to 6000 ml

Solution C₁

Potassium bromide	1327 g
1-Phenyl-5-mercaptotetrazole (dissolved in methanol)	0.3 g
Water was added to	3000 ml

Solution D₁

Aqueous ammonia (28%) 705 ml
Solutions B₁ and C₁ were added in 30 seconds by the double-jet method to solution A₁ being vigorously stirred at 40°C, so that nuclei were formed. During the addition, the pBr was kept in the range of 1.09 to 1.15.
After 1 minute and 30 seconds, solution D₁ was added thereto in 20 seconds, followed by a 5-minute ripening at a KBr concentration of 0.071 mol/l and an ammonia concentration of 0.63 mol/l. Then, the pH was adjusted to 6.0, and desalting and washing were carried out immediately. Electron microscopic observations of the resulting seed emulsion proved that the emulsion comprised monodispersed spherical grains having an average grain size of 0.36 µm and a grain size distribution extent of 18%.

(10) Preparation of Comparative Emulsion (Em-10)

A comparative emulsion, Em-10, was prepared according to the following procedure.

Solution J

Ossein gelatin	76.8 g
Potassium bromide	3.0 g
Disodium propyleneoxy-polyethyleneoxy disuccinate (10% methanol solution)	10 ml
Seed emulsion (Em-9)	0.191 mol equivalent
Nitric acid (s.g. 1.38)	4.5 ml
Water was added to	4000 ml

Solution K

Silver nitrate	194.5 g
Nitric acid (s.g. 1.38)	4.1 ml
Water was added to	1309 ml

Solution L

Ossein gelatin	52.4 g
Potassium bromide	95.4 g
Potassium iodide	57.0 g
Water was added to	1309 ml

Solution M

Silver nitrate	195.4 g
Nitric acid (s.g. 1.38)	2.0 ml
Water was added to	575 ml

Solution N

Ossein gelatin	23.0 g
Potassium bromide	116.3 g
Potassium iodide	28.6 g
Water was added to	575 ml

Solution P

Silver nitrate	777.6 g
Nitric acid (s.g. 1.38)	8.1 ml
Water was added to	2289 ml

Solution Q

Ossein gelatin	91.6 g
Potassium bromide	539.4 g
Potassium iodide	7.60 g
Water was added to	2289 ml

The apparatus disclosed in Japanese Pat. O.P.I. Pub. No. 160128/1987 was arranged so as to be able to feed each of solutions K and L beneath the mixing blade through six nozzles.
While stirring solution J at 450 rpm and at 75°C, solutions K and L were added thereto by the double-jet method at an initial flow rate of 11.62 ml/min and a final flow rate of 25.63 ml/min. During the addition, the flow rate was linearly increased against addition time, and the pAg was kept at 8.2. After completing the addition, the pAg was adjusted to 8.45 with 3.5 N aqueous solution of potassium bromide, and the stirring speed was raised to 500 rpm.
Subsequently, solutions M and N were added to the reaction system by the double-jet method, while linearly increasing the flow rate against addition time from 15.59 ml/min at the start of addition to 18.51 ml/min at the end of addition. During the addition, the flow rate was linearly increased against addition time the pAg was kept at 8.45. After completing the addition of solutions M and N, the stirring speed was raised to 500 rpm.
Next, solutions P and Q were added to the reaction system by the double-jet method at an initial flow rate of 41.19 ml/min and a final flow rate of 68.07 ml/min. During the addition, the flow rate was linearly increased against addition time, and the pAg was kept at 8.45.
After completing the addition, the pH was adjusted to 6.0 with 1.78 N aqueous solution of potassium hydroxide, followed by desalting in the usual manner.
Electron microscopic observations of the silver halide grains contained in the resulting emulsion proved that the grains were tabular grains having an average grain size of 1.27 µm, a grain size distribution extent of 14.0% and an average aspect ratio of 3.1.

(11) Preparation of Emulsion of the Invention (Em-11)

An emulsion of the invention, Em-11, was prepared in the same manner as the comparative emulsion, Em-10, except that 5 minutes after starting the addition of solutions K and L, the following solution R-1 was added to solution J in 30 seconds at a constant rate.

Solution R-1

Methanol solution containing iodine of 0.0006 mols per mol of silver halide grains of emulsion (Em-10) 100.0 ml
The silver halide grains contained in the resulting emulsion were tabular grains having an average grain size of 1.27 µm, a grain size distribution extent of 13.7% and an average aspect ratio of 3.1.

(12) Preparation of Emulsion of the Invention (Em-12)

An emulsion of the invention, Em-12, was prepared in the same manner as the comparative emulsion, Em-10, except that 5 minutes and 50 minutes after starting the addition of solutions K and L, the following solutions R-2 and R-3 were added in 30 seconds to solution J at constant rates, respectively.

Solution R-2

Methanol solution containing iodine of 0.0003 mols per mol of silver halide grains of emulsion (Em-10) 50.0 ml

Solution R-3

Methanol solution containing iodine of 0.0003 mols per mol of silver halide grains of emulsion (Em-10) 50.0 ml
The silver halide grains contained in the resulting emulsion were tabular grains having an average grain size of 1.24 µm, a grain size distribution extent of 14.4% and an average aspect ratio of 3.0.

(13) Preparation of Emulsion of the Invention (Em-13)

An emulsion of the invention, Em-13, was prepared in the same manner as the comparative emulsion, Em-10, except that the following solution R-4 was added to solution J at a constant rate over a period of 65.17 minutes between 5 minutes and 70.17 minutes after starting the addition of solutions K and L.

Solution R-4

Methanol solution containing iodine of 0.0006 mols per mol of silver halide grains of emulsion (Em-10) 200.0 ml
The silver halide grains contained in the resulting emulsion were tabular grains having an average grain size of 1.29 µm, a grain size distribution extent of 14.2% and an average aspect ratio of 3.2.
The characteristics of emulsions Em-10 to Em-13 are shown in Table 6.
Emulsions Em-10 to Em-13 was subjected to optimum chemical ripening. Using these emulsions, samples 21 to 24 of multilayered color photographic light-sensitive material were prepared as in Example 1, which were then processed and evaluated for sensitivity and RMS graininess in the same manner as in Example 1.
The evaluation results of sample Nos. 21 to 24 using emulsions Em-10 to Em-13 are shown in Table 7 in relative values. Table 7

Sample No. Emulsion No. Class Relative Sensitivity RMS (relative value)

21 Em-10 Comparison 100 100

22 Em-11 Invention 115 93

23 Em-12 Invention 120 88

24 Em-13 Invention 123 86
It can be understood from Table 7 that sample Nos. 22 to 24 using emulsions Em-11 to Em-13 of the invention had better relative sensitivities and RMS graininesses when compared with the sample using the comparative emulsion. And much better results were obtained when the addition of the halide element was made in two separate times, or was made continuously.

Example 4

The preservability of sample Nos. 21 to 24 of Example 3 was evaluated by storing and testing them in the same manner as in Example 2. The evaluation results are shown in Table 8 (condition A) and Table 9 (condition B). Table 8

Sample No. Emulsion No. Class Relative Sensitivity RMS (relative value)

21 Em-10 Comparison 100 100

22 Em-11 Invention 116 93

23 Em-12 Invention 116 88

24 Em-13 Invention 119 84

Table 9

Sample No. Emulsion No. Class Relative Sensitivity RMS (relative value)

21 Em-10 Comparison 100 100

22 Em-11 Invention 120 90

23 Em-12 Invention 119 86

24 Em-13 Invention 125 80
As is seen in Tables 8 and 9, sample Nos. 22 to 24 using emulsions Em-11 to Em-13 of the invention were superior to the sample using the comparative emulsion in both relative sensitivity and RMS graininess when stored under canditions A and B. And much better results were obtained when the addition of the halogen element was made in two separate times, or continuous addition was carried out.

EFFECTS OF THE INVENTION

The invention have the effect of improving the sensitivity, graininess and preservability simultaneously owing to silver halide grains formed by adding a halogen element after starting the substantial growth of the silver halide grains in the formation of the silver halide grains.
This effect is markedly exhibited when iodine is used as halogen element, and when the halogen element is added during the formation of silver halide phases containing silver iodide in an amount of 5 mol% or more.

Claims

A silver halide photographic emulsion comprising silver halide grains and a protective-colloid-containing aqueous solution, wherein the silver halide grains are formed by adding a halogen element, after the initiation of the growth of the silver halide grains, to the protective-colloid-containing aqueous solution where the silver halide grains are being grown.
The silver halide photographic emulsion of claim 1, wherein the halogen element is iodine.
The silver halide photographic emulsion of claim 2, wherein said iodine is dissolved in methanol.
The silver halide photographic emulsion of claims 1, 2 or 3, wherein the silver halide grains grow while the halogen element is added before consumption of 50 % of the total amount of silver halide.
The silver halide photographic emulsion of claim 2, wherein the halogen element is added during the formation of silver halide phases containing 5 mol% or more of silver iodide.
The silver halide photographic emulsion of claim 4, wherein the halogen element is added during the formation of silver halide phases containing 5% or more silver iodide.
The silver halide photographic emulsion of claim 2, wherein the addition of the halogen element is made in two or more parts over.
The silver halide photographic emulsion of claim 2, wherein the addition of the halogen element is made continuously.
The silver halide photographic emulsion of claims 1, or 2 to 8, wherein said silver halide grains are tabular grains, and the average aspect ratio of said tabular grains is from 1.3 to less than 5.0.
The silver halide photographic emulsion of claims 1, or 2 to 8, wherein said silver halide grains are tabular grains, and the average aspect ratio of said tabular grain is from 1.5 to less than 4.5.
The silver halide photographic emulsion of claims 1, or 2 to 8, wherein said silver halide grains are tabular grains, and the average aspect ratio of said tabular grains is from 2.0 to less than 4.5.
The silver halide photographic emulsion of claims 1, or 2 to 11, wherein diameters of said silver halide grains are 0.1 µm to 5.0 µm.
The silver halide photographic emulsion of claims 1, or 2 to 11, wherein diameters of said silver halide grains are 0.2 µm to 4.0 µm.
The silver halide photographic emulsion of claims 1, or 2 to 11, wherein diameters of said silver halide grains are 0.3 µm to 3.0 µm.
The silver halide photographic emulsion of claims 1, or 2 to 14, wherein said silver halide emulsion is a monodispersed emulsion.
The silver halide photographic emulsion of claim 15, wherein said monodispersed emulsion contains monodispersed silver halide grains, and the weight of said grains having the grain sizes within the range of ±20 % around the average grain size r is not less than 60 % of the total weight of the silver halide grains.
The silver halide photographic emulsion of claim 15, wherein said monodispersed emulsion contains monodispersed silver halide grains, and the weight of said grains having the grain sizes within the range of ±20 % around the average grain size r is not less than 70 % of the total weight of the silver halide grains.
The silver halide photographic emulsion of claim 15, wherein said monodispersed emulsion contains monodispersed silver halide grains, and the weight of said grains having the grain sizes within the range of ± 20 % around the average grain size r is not less than 80 % of the total weight of the silver halide grains.
The silver halide photographic emulsion of claims 1, or 2 to 18, wherein the addition amount of the halogen element is 10⁻⁸ to 10⁻¹ mol.
A silver halide photographic emulsion comprising silver halide grains and a protective-colloid-containing aqueous solution, wherein the silver halide grains are formed by adding iodine, after the initiation of the growth of the silver halide grains, to the protective-colloid-containing aqueous solution where the silver halide grains are being grown, and the growth of silver halide grains is made by adding the halogen element before completing 50% of the growth in silver halide amount.