JPH1184558A - Silver halide photographic emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a silver halide emulsion having improved relation between sensitivity comparable to that of silver iodobromide and graininess, excellent also in rapid processability and less liable to a change in performance even after storage in an environment at high humidity. SOLUTION: The emulsion contains a dispersion medium, silver halide particles including flat platy particles and a spectral sensitizing dye adsorbecl on the surfaces of the flat platy particles. The flat platy particles have (111) principal faces and an aspect ratio of >=2, account for >90% of the total projection area of all the silver halide particles and also have at least 0.7 μm average diameter equivalent to the diameter of a circle, <0.3 μm average thickness and latent image forming chemically sensitized parts on the surfaces of the flat platy particles. The latent image forming chemically sensitized parts contain epitaxial-stuck silver halide protrusions forming epitaxial joints to the flat platy particles and having a rock salt type face-centered cubic crystal lattice structure. The protrusions account for <50% of the (111) principal faces of the flat platy particles and are positioned closest to the peripheral edges of the flat platy particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silver halide photographic emulsion (hereinafter, also simply referred to as an emulsion). More particularly, the present invention relates to silver halide photographic emulsions having improved spectral sensitization.

[0002]

2. Description of the Related Art Currently available silver halide color photographic light-sensitive materials (hereinafter, also simply referred to as light-sensitive materials) and image forming methods using the same are used in various fields in various fields. (U.S. Pat. No. 4,439,520) describe that tabular silver halide grains having a diameter of at least 0.6 .mu.m and a thickness of less than 0.3 .mu.m exhibit an aspect ratio greater than 8 and a total grain projected area. The remarkable photographic advantages of chemically and spectrally sensitized tabular emulsions which account for more than 50% of the above are disclosed and shown. On the other hand, the halogen composition used in many light-sensitive materials is often silver iodobromide, silver chloroiodobromide or silver chlorobromide, mainly silver bromide, for the purpose of achieving high sensitivity. . On the other hand, the demand for rapid processing of color photographic light-sensitive materials has been increasing in recent years,
For that purpose, it is necessary to provide a silver halide photographic material using an emulsion having a relatively high silver chloride content.

However, silver halide emulsions having a relatively high silver chloride content have lower sensitivity than silver iodobromide emulsions, and have been difficult to use in photographic materials. Further, since the high silver chloride emulsion has a higher solubility than the silver bromide emulsion, there is a disadvantage that the sensitivity is significantly reduced when the photographic material is stored under high humidity. On the other hand, as a technique for improving photographic performance, a method of giving epitaxy to host particles is generally well known. This technique is disclosed in U.S. Pat.
No. 50l (Masksky) (hereinafter referred to as “Maska
kasky1 "). Mask
Asky1 is a site director such as iodide ion, aminoazaindene or selected spectral sensitizing dye adsorbed on the surface of the host tabular grains.
r) could direct silver salt epitaxy to selected sites, typically the edges and / or corners of the host grains. Depending on the composition and site of the silver salt epitaxy, the sensitivity increased significantly.

No. 4,471,050 (Mas)
Kasky) specification (hereinafter referred to as Maskasky2)
Discloses that non-isomorphic silver salts can be selectively deposited on the edges of silver halide host grains without resorting to additional site directors. This non-isomorphous silver salt includes silver thiocyanate, β
Phase silver iodide (having a hexagonal wurtz type crystal structure),
Includes gamma-phase silver iodide (having a zinc-containing crystal structure), silver phosphate (including meta and pillow phosphates) and silver carbonate. None of these non-isomorphic silver salts exhibit the face-centered cubic crystal structure of the type found in photographic silver halide (ie, rock salt-type isomorphous face-centered cubic crystal structure).

In practice, the sensitivity enhancement caused by non-isomorphic silver salt epitaxy was less than that obtained with comparative isomorphous silver salt epitaxial sensitization. However, as described above, silver iodobromide was mainly used as the halogen composition of the host grains. On the other hand, US Pat.
As disclosed in US Pat. No. 2,927 (Deltan), contains 0.4 to 20 mol% of silver chloride based on total silver for forming ultrathin tabular grains having a thickness of 0.07 μm or less. There is an example in which the purpose is to reduce the thickness of the flat plate, which is completely different from the object of the present invention.

[0006]

SUMMARY OF THE INVENTION Despite the numerous advantages of general tabular grain emulsions and the particular improvement in the color photographic materials in which they are used, tabular tabulations not available in the art. There remains an unmet need for improved performance in granular emulsions.

Accordingly, an object of the present invention is to improve the relationship between sensitivity and granularity equivalent to that of silver iodobromide, to have excellent rapid processing properties, and to have little change in performance even when stored in a high humidity environment. An object of the present invention is to provide a silver photographic emulsion.

[0008]

The above object of the present invention is attained by the following constitutions.

1. A dispersion medium, having a (111) major surface, having an aspect ratio of 2 or more with respect to silver, accounting for more than 90% of the total grain projected area, and having an average equivalent circular diameter of at least 0.7 μm; Silver halide grains containing tabular grains having a thickness of less than 0.3 μm and having latent image forming chemical sensitizing sites on the surfaces of the tabular grains, and spectral sensitizing dyes adsorbed on the surface of the tabular grains Wherein the latent image-forming chemically sensitized site has an epitaxially deposited silver halide having a rock-salt type face-centered cubic crystal lattice structure forming an epitaxial junction with the tabular grains. A protrusion comprising less than 50% of the (111) major surface of the tabular grain, wherein the protrusion comprises a tabular grain located closest to a peripheral edge of the tabular grain. C characterized by being limited Silver halide photographic emulsion.

[0010] 2. At least one ligand having a higher electron-withdrawing property than fluoride ions and Fe ²⁺ , O
s ²⁺ , Ru ²⁺ , Co ²⁺ , Rh ³⁺ , Ir ³⁺ , Pd ⁴⁺ or P
2. The silver halide photographic emulsion according to the above item 1, which contains a divalent Group VIII dopant selected from t ⁴⁺ .

That is, the tabular grain emulsion of the present invention uses silver halide epitaxy for its chemical sensitization, and has a relatively high silver chloride content which has conventionally been low in sensitivity and rarely used in color emulsions. It achieves high sensitivity and low granularity using silver chlorobromide and silver chloroiodobromide emulsions, and is excellent in rapid processing.

Hereinafter, the present invention will be described in more detail.

In preparing the tabular emulsion of the present invention, a silver halide precipitation method well known in the art can be used. Generally, the preparation of grains having a (111) major plane involves a nucleation step, an ripening step, and a growing step. In some cases, desired tabular grains can be obtained only by the nucleation and ripening steps. The use of gelatin as the protective colloid during grain formation is most effective, but is not particularly limited as long as it acts as a protective colloid for silver halide, and various synthetic polymers can be used. During the growth process, the addition of silver and halogen salts is performed by a single jet as a salt solution,
The double jet method can be used, but part or all of the method may be carried out by adding fine silver halide grains (for example, Lippmann emulsion) which have been adjusted in advance.

The tabular grains occupying more than 90% of the total grain projected area in the tabular grains of the present invention preferably have an average thickness of less than 0.03 μm. For recording in the minus blue (green and / or red) portion of the spectrum, the thickness of the tabular grains is preferably small. The thickness is more preferably 0.2 μm or less, and still more preferably 0.1 μm or less. When the average thickness is 0.1 μm or less, it is necessary to appropriately select emulsion adjustment conditions. Preferred tabular grain emulsions are those in which the variation between grains is kept at a low level. It is preferable that 80% or more of the tabular grains have a hexagonal main plane. Preferred tabular emulsions have an average isometric diameter (E
The coefficient of variation (COV) for CD) is less than 30%, more preferably less than 20%. The halogen composition of the host particles in the present invention preferably has a bromide concentration of 70 mol% or less and a chloride content of 20 mol% or more, more preferably 40% or more, and still more preferably 60% or more.

The chloride content of 50% or more may be at least 50% of the total silver halide after the growth of the host grains, and the halogen composition during nucleation and growth during the growth may be irrespective of the above ratio. Can be changed as desired.
When the chloride content exceeds 30%, the crystal surface becomes mainly a (100) plane as a property of the silver chloride particles. Therefore, it is preferable to use a growth modifier well known in the art. The growth modifier may be any compound as long as it is a compound that adsorbs to particles to give a (111) plane, and two or more kinds may be mixed. For example, US Pat. No. 4,399,215, US Pat. No. 4,414,306, US Pat.
No. 463, U.S. Pat. No. 4,713,323,
JP-A-2-163046, JP-A-2-32, JP-A-6-1
No. 1787 can be referred to. Specific examples include triaminopyrimidine, iodophenol, 8-hydroxyquinoline having an iodo substituent, 2-hydroaminoazine, and the like. These may be added at any point during the growth, but particularly preferably at the initial stage of grain growth, and more preferably during the nucleation. The concentration of the control agent is 0.1 to 50 per mole of silver.
The range of 0 mmol is preferable from the viewpoint of the effect of the present invention. Further, the preferred concentration is 0.4
~ 200 mmol, optimally 4 ~ / mol silver
100 mmol. The tabular emulsion of the present invention may contain a dopant which reduces high intensity reciprocity failure.

As the dopant, an Ir dopant is particularly preferred. A specific example of the Ir dopant is Iwaos.
a, et al., US Pat. No. 3,901,711; Grz
U.S. Pat. No. 4,828,962 to Eskowiak et al .; U.S. Pat. No. 5,051,344 to Kuno; U.S. Pat. No. 5,229,26 to Yoshida et al.
No. 3 is described in the specification. A more general investigation of Ir dopants used to reduce reciprocity failure and other objectives can be found in B.S. H. Carroll's Iridium Sensitization: Review of Literature "Photographic Sci"
ence and Engineering "(No. 24
Vol. 6, No. 12 / Dec 1980, Nos. 265-26
7). Any conventional dopant known to reduce high intensity reciprocity failure can be used in any amount known to be useful for the purposes of the present invention in practicing the present invention. .

In a particularly preferred embodiment, the iridium dopant is incorporated in the crystal lattice structure of the particles in the form of a hexacoordination complex satisfying the following general formula (1).

Formula (1) [Ir ⁺³ X ₅ L '] ^{m wherein} X is a halide ligand, L' is a bridging ligand, and m is ^-2 or ^-3. It is. When iridium is added during the precipitation step, the hexacoordination complex is accompanied by an appropriate counter ion such as ammonium or alkali metal, but only the anion portion of the general formula (1) is actually contained in the crystal lattice structure. Is introduced.

The iridium dopant is at least 20% (most preferably 60%) of the silver forming the tabular grains.
And preferably before 90% (most preferably 80%) of the silver forming the tabular grains is precipitated.

If the time of adding iridium in the precipitation step is earlier than the above, nucleation of tabular grains becomes complicated. In order to completely incorporate iridium completely in the tabular grains, it is necessary to avoid delay in addition of iridium in the precipitation step. Preferred concentrations of iridium dopant can range up to between about 300 mppb. As the halogen composition of the projections deposited on the host grains, any of silver chloride, silver bromide, silver chlorobromide, silver chloroiodide, silver bromoiodide, and silver chloroiodobromide can be selected. By incorporating silver iodide, the sensitivity and graininess characteristics of the emulsion can be improved. Since the developing speed decreases as the bromide and iodide concentrations increase, it is necessary to appropriately select the epitaxial amount, bromide and iodide concentrations. 5 to 9 based on the total halogen content of the epitaxy part
A bromide concentration of 0 mol% is preferred, and an iodide concentration of 0.25 to 20 mol% is more preferred. More preferably, 10
A bromide concentration of 50 mol%, an iodide concentration of 1 to 10 mol% is preferred.

A variety of techniques can be used to limit the surface coverage of host tabular grains by silver halide epitaxy applicable to the formation of the emulsions of this invention.
Dyes constitute a specifically preferred polar site community. Spectral sensitizing dyes can be used in the form of aggregates in which silver halide epitaxy is adsorbed on the surface of tabular grains which can be directed toward the edges or corners of the tabular grains.

J-Cyanine adsorbed on the surface of host tabular grains in agglomerated form. Directing epitaxy to the edges or corners of tabular grains using a colorless adsorption site director such as aminoazaindene (eg, adenine). Can also. In addition, epitaxy can be directed to the edges or corners of the tabular grains, with the total iodide level in the host tabular grains being at least 8 mole percent.
In addition, lower levels of iodide can be adsorbed on the surface of the host tabular grains to direct epitaxy to the edges and / or corners of the grains. The above site-directing techniques are interchangeable and are used in combination in a specifically preferred embodiment of the present invention.

For example, the iodide in the host particle is
Adsorption surface site director (s) (e.g., e.g.,) in epitaxy localization, even if they do not reach the 8 mol% level at which epitaxy alone can be directed to the edges or corners of the host tabular grains.
(A spectral sensitizing dye and / or adsorbed iodide). Selective site attachment of silver halide epitaxy to host tabular grains generally reduces sensitization site competition for conduction band electrons emitted by photon absorption during imagewise exposure, thus improving sensitivity. It is said.

That is, the epitaxy of a limited portion of the main surface of the tabular grain is more efficient than the epitaxy covering all or most of the main surface, and more preferably, the epitaxy is substantially at the edge of the host tabular grain. Epitaxy is limited in nature and has limited coverage on the major surface, and more efficient is epitaxy limited to or near the corners of tabular grains or other discrete sites. The spacing of the major surface corners of the host tabular grains themselves reduces photoelectron competition sufficiently to achieve near maximum sensitivity.

The term "dopant" used in the present invention
Means a substance other than silver or halide ions contained in the face-centered cubic crystal lattice structure of silver halide forming tabular grains.

When the dopant is introduced at a high concentration and / or before, during or immediately after nucleation of the grains, it contributes to an increase in the thickness of the tabular grains during precipitation. The particles are, as shown in the examples herein,
The dopant can be formed during the grain growth. At this time, the introduction of the dopant is delayed until after the formation of the grains, and the quota is introduced at the beginning of the grain growth, and is preferably continued as it is or throughout the entire post-stage of the tabular grain growth.

It has also been found that these same dopants can be introduced with silver salts that epitaxy adhere to the tabular grains, while avoiding any increase in tabular grain thickness. Any of the usual dopants known to be useful in silver halide face centered cubic crystal lattice structures can be used. Photographically useful dopants selected from a wide range of periods and groups within the periodic table of elements have been reported. As used herein, the cycle and family are Ame
adopted by Chemical Chemical Society, Chemical and Engineering
Ring News, February 4, 1985, page 26, based on the periodic table of elements.

Typical dopants include Fe, Co, N
i, Ru, Rh, Pd, Re, Os, Ir, Pt, M
g, A1, Ca, Sc, Ti, V, Cr, Mn, Cu,
Zn, Ga, Ge, As, Se, Sr, Y, Mo, Z
r, Nb, Cd, In, Sn, Sb, Ba, La, W,
Periods 3 to 7 (most commonly periods 4 to 6) of the periodic table of elements such as Au, Hg, Tl, Pb, Bi, Ce, and U
Ions from The dopants include (a) increased sensitivity, (b) reduced high or low illumination reciprocity failure,
(C) increase, decrease or decrease in contrast fluctuation;
(D) reduced pressure sensitivity, (e) reduced dye desensitization,
(F) increased stability (including reduced thermal instability);
It can be used for (g) decreasing the minimum density and / or (h) increasing the maximum density.

For certain polar applications, any polyvalent metal ion is effective. The following are examples of common dopants that can produce one or more of the above effects when incorporated by silver halide epitaxy = B. H. Ca
rroll, "Iridium Sensitizat
ion: ALiterature Review ”,
Photographic Science and
Engineering, Vol. 24, No., November / December, 1980, pp. 265-267; U.S. Pat.
No. 51,933 (Hochsetter) and U.S. Pat. No. 2,628,167 (De Wit).
t), U.S. Pat. No. 3,687,676 (Spe
U.S. Patent No. 3,761,267 (Gilman et al.); U.S. Patent No. 3,890,154 (Ohkubo et al.); U.S. Patent No. 3,901,7
No. 11 (Iwaosa et al.), US Pat. No. 3,90
U.S. Patent No. 4,713,483 (Habu et al.); U.S. Patent No. 4,269,927 (Atwell); U.S. Patent No. 4,413,055. U.S. Pat. No. 4,477,561 (Menjo)
U.S. Pat. No. 4,581,327 (Hab).
u et al.); U.S. Pat. No. 4,643,965 (Ku
bota et al.), U.S. Pat. No. 4,806,462 (Yamashita et al.); U.S. Pat. No. 4,828,9
No. 62 (Grzeskowiak et al.); U.S. Pat. No. 4,835,093 (Janusonsi)
s); U.S. Pat. No. 4,902,611 (Leu)
US Pat. No. 4,981,780 (Inoue et al.); US Pat. No. 4,997,751 (Kim); US Pat. No. 5,057,402 (Shiba et al.) U.S. Pat. No. 5,134,060 (Maekawa et al.); U.S. Pat. No. 5,153,1
No. 10 (Kawai et al.); U.S. Pat.
No. 4,292 (Johnson et al.); U.S. Pat. Nos. 5,166,044 and 5,204,234.
No. (Asami); US Pat. No. 5,166,04.
U.S. Patent No. 5,229,263 (Yoshida et al.); U.S. Patent No. 5,252.
No. 451 and 5,252,530 (B
ell); EPO 0244184 (Komo)
Rita et al.); EPO 0488737 and 0488601 (Miyoshi et al.); EPO
No. 0368304 (Ihμma etc.); EPO 0405938 (Tashiro); EPO 0509674 and 0563946 (Murakami etc.) and Japanese Patent Application No. 2-249588 and WO 93 / 02390 (Bud
z).

When the dopant metal is present in the precipitate in the form of a coordination complex, especially a tetra- and hexa-coordination complex,
Both metal ions and coordinating ligands can be stored in the particles. U.S. Pat. No. 4,847,191 (Grze
Skowiak), U.S. Pat. Nos. 4,933,272, 4,981,781 and 5,055.
No. 37,732 (McDuggle et al.), US Pat. No. 937,180 (Marchetti et al.),
U.S. Pat. No. 4,945,035 (Keert
Et al.), US Pat. No. 5,112,732 (Hay
ashi), EPO 0509674 (Mur
AKAMI et al.), EPO 0513738 (O
hya et al.), WO 91/10166 (Jan
usonis), WO 92/16876 (Bea)
vers), halo, aquo, cyano, cyanate, flumate, thiocyanate, selenocyanate, tellurocyanate, nitrosyl, thionitrosyl, as indicated by DD 298,320, Germany (Pietsch et al.). Azide, oxo, carbonyl, and ethylenediaminetetraacetic acid (EDTA) ligands have been disclosed, and in some cases, improved ligand properties have been observed with the ligands. U.S. Pat. No. 5,360,712 (olm et al.) Discloses hexaligand complexes containing organic ligands, while U.S. Pat. No. 4,092,171 (Bige1ow) discloses Pt and Pd Disclosed are organic ligands in coordination complexes.

It is specifically contemplated to incorporate a dopant into the tabular grains to reduce reciprocity failure. Iridium is a preferred dopant for reducing reciprocity failure. Carroll, Iwaosa, etc., Habu
Etc., Grzeskowiak, etc., Kim, Maekawa
a, Johnson, etc., Asami, Yoshida
Et al., Bell, Miyoshi et al., And the technique described in Tashiro and EPO 0509674 (Mur.
Akami et al.) are typical. These techniques can be applied to the emulsions of the invention by simply incorporating the dopant during the silver halide precipitation. In another particularly preferred embodiment of the present invention, it is conceivable to incorporate into the face-centered cubic crystal lattice of the tabular grains a dopant capable of increasing photographic sensitivity by forming shallow electron traps. Research Disclosur
e, Volume 367, November 1994, item 3673
6 provides a straightforward description of the criteria for selecting shallow electron trap (SET) dopants. In certain preferred embodiments, it is contemplated to use a hexa-coordination complex satisfying the following general formula (2) as a dopant.

Formula (2) [ML ₆ ] ⁿ (where M is a charged frontier orbital polyvalent metal ion, preferably Fe ⁺² ,
Ru ⁺² , Os ⁺² , Co ⁺³ , Rh ⁺³ , Ir ⁺³ , Pd ⁺⁴ or Pt ⁺⁴ ; L ₆ represents _six independently selectable coordination complex ligands With the proviso that at least four of the ligands are anionic ligands, and at least one (preferably at least three and optimally at least four) of the ligands is more electronegative than any halide ligand; Is ^-2 , ^-3 or ^-4 . Specific examples of dopants that can provide a shallow electron trap are shown below.

SET-1 [Fe (CN) ₆ ] ^-4 SET-2 [Ru (CN) ₆ ] ^-4 SET-3 [Os (CN) ₆ ] ^-4 SET-4 [Rh (CN) ₆ ] ^{- 3} SET-5 [Ir (CN) ₆ ] ^-3 SET-6 [Fe (pyrazine) (CN) _k ] ^-4 SET-7 [RuCl (CN) ₅ ] ^-4 SET-8 [OsBr (CN) _5] ^-4 SET-9 [Rh F (CN) _5] ^-3 SET-10 [Ir Br (CN) _5] ^-3 SET-11 [Fe CO (CN) _5] ^-3 SET-12 [Ru F ₂ (CN) ₄ ] ^-4 SET-13 [OsCl ₂ (CN) ₄ ] ^-4 SET-14 [RhI ₂ (CN) ₄ ] ^-3 SET-15 [IrBr ₂ (CN) ₄ ] ^-3 SET -16 [Ru (CN) ₅ (OCN)] ^-4 SET-17 [Ru (CN) ₅ (N ₃ )] ^-4 SET-18 [Os (CN) ₅ (SCN)] ^-4 SET-19 [Rh (CN) ₅ (SeCN)] ^-3 SET-20 [Ir (CN) ⁵ (HOH)] ^-2 SET-21 [Fe (CN) ₃ Cl ₃ ] ^{- 3} SET-22 _{[Ru (CO) 2 (CN)} 4 ] ^-l SET-23 [Os (CN) C1 _5] ^-4 SET-24 [Co (CN) _6] ^-3 SET-25 [IF (CN) ₄ (oxalate)] ^-3 SET-26 [In (NCS) ₆ ] ^-3 SET-27 [Ga (NCS) ₆ ] ^-3 Further, US Pat. No. 5,024,931 (Ev
sensitization can also be achieved using oligomeric coordination complexes, as taught in US Pat.

The dopant is effective at a normal concentration (where the concentration is a concentration based on the total silver including both silver in tabular grains and silver in protrusions). In general, the shallow electron trap-forming dopant should be present in a concentration of at least 1 × 10 ⁻⁶ mole per silver mole to the solubility limit (typically a concentration of about 5 × 10 ⁻⁴ mole per silver mole or less).
It is preferable to take in with. A more preferred concentration is silver 1
It is in the range of about 10 ^-5 to 10 ^-4 mole per mole. Of course,
The dopant can be distributed such that a portion is incorporated into the tabular grains and the remainder is incorporated into the silver halide protrusions.

The tabular silver halide emulsion of the present invention is preferably subjected to chemical sensitization with chalcogen represented by sulfur and / or gold. Tabular grains having silver halide protrusions arranged epitaxially increase sensitivity to an extent comparable to that obtained by substantially optimal chemical sensitization with sulfur and / or gold per se. It is preferable that the tabular grains on which silver halide is epitaxially arranged are subjected to chemical sensitization, because the sensitivity is further increased.

A known method can be applied to the chemical sensitization method, for example, Research Disclosure, 1989.
December, Item 308119, Section III, Chemical Sensitization. Various known chemical sensitizers can be applied. Particularly in the case of tabular grains having silver halide protrusions arranged epitaxially, the sulfur sensitizer is combined with a middle chalcogen (typically sulfur) and a noble metal (typically gold) chemical sensitizer. Preferably, it is used. The above sulfur sensitizers include U.S. Pat.
No. 71,157, No. 3,574,628, No. 3,
737,313 and the like. Preferred sulfur sensitizers are described in U.S. Pat.
No. 2,264, No. 2,448,534, No. 3,3
Thiocyanates described in JP-A-20,069 and the like. Preferred types of middle chalcogen sensitizers are described in U.S. Patent Nos. 4,749,646 and 4,810,626.
And other tetra-substituted middle chalcogen ureas.

The tabular silver halide emulsion of the present invention is preferably subjected to spectral sensitization in order to increase sensitivity to light in a specific wavelength range. Various known sensitizing dyes and spectral sensitizing dyes can be used.
arch Disclosure, December 1989,
Item 308119, Section IV, "Spectral Sensitization and Desensitization". In the case of tabular grains having silver halide projections arranged epitaxially, a spectral sensitizing dye is often already adsorbed as a site directing substance at the time of epitaxial deposition as described above, which is particularly advantageous. In this case, it is preferable to appropriately select and use the spectral sensitizing dye to be added at the time of epitaxial deposition, and it is also possible to further add a spectral sensitizing dye in the sensitizing step as needed.

[0038]

EXAMPLES The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

In the following examples, the halide ion concentration is expressed in mol% (M%) based on silver.

The sensitivity is represented by the relative value of the logarithm of the reciprocal of the exposure amount E (E is expressed in units of lux-second) giving a density of fog of 0.2.

Example 1 Emulsion A: Silver iodobromide tabular emulsion (comparative) 3.75 lime-processed bone gelatin was placed in a container equipped with a stirrer.
g, 4.76 g of KBr, an antifoaming agent, and 6 liters of sulfuric acid and water sufficient to adjust the pH to 1.8 at 39 ° C. AgNO ₃ solution and halide (KBr and K
I and 98.5 M% and 1.5 M%, respectively, of a solution (both 2.5 M) in a sufficient amount to produce 0.01335 mol of silver iodobromide, achieved by simultaneous addition. During the nucleation performed, the pBr and pH were almost maintained at the values initially set in the solution in the reactor. Following nucleation, the temperature was increased to 54 ° C for 9 minutes. After holding the reactor and its contents at this temperature for 9 minutes, a solution of 100 g of lime-processed bone gelatin in 1.5 liter of water was added to the reactor at 54 ° C. Next, the pH was adjusted to 5.9.
0 and 1 M KBr solution was added to the reactor.
24.5 minutes after nucleation, the growth phase begins, during which 2.5 M AgNO ₃ , 2.8 M KBr and AgI
(Lippmann) 0.148M suspension was prepared by
3.0M iodide in the growing silver halide crystal
% And (b) 0.8% silver iodobromide.
Until 48 moles were formed, pBr in the reactor was added proportionally (53.33 minutes, constant flow) to maintain the value obtained by the addition of KBr before the onset of nucleation and growth. Thereafter, 1M KBr was added to adjust the excess Br ^- concentration, and the addition was continued until the pBr became 2.20. Subsequently, 2.5M AgNO ₃ , 2.8M
0.148M of KBr and AgI (Lippmmann)
The flow of the suspension was resumed (additional flow was accelerated, segment initial flow: segment final flow = 1: 12.6).

Further, the addition was carried out when the pBr in the reactor was 2.20.
2.8 M KBr and AgI (Lip
pmann) at a controlled flow rate of the 0.148M suspension. As a result, the total amount of silver iodobromide was 9 mol (3.0 mol).
M% I). When the addition of AgNO ₃ , AgI and KBr was completed, the resulting emulsion layer was coagulated and washed to adjust the pH and pBr to storage values of 6 and 2.5, respectively.

The obtained emulsion was subjected to scanning electron microscopy (SE
M). Tabular grains accounted for more than 99.5% of total grain projected area. Average EC of the emulsion
D was 1.90 μm and their COV was 32.

Since the tabular grains account for almost all of the grains present, the average grain thickness was measured using the dye adsorption method described below. The level of the 1,1'-diethyl-2,2'-cyanine dye required for the saturated coating amount was measured, and the solution absorption coefficient of this dye was 77,300 liter / (mol · cm), 0.566 per part area
Assuming that the nm ^2, and the equation for surface area was solved. The average thickness of the emulsion grains determined from the dye adsorption measurement is
0.140 μm (aspect ratio 12.6).

Emulsion B: silver chloroiodobromide tabular emulsion (comparative) 10 g of lime-processed bone gelatin and Na in a vessel equipped with a stirrer
5.5 g of Cl, defoamer, 2500 cc of pure water and 40 ° C.
Add sufficient amount of sulfuric acid to adjust the pH to 5.0 with
The mixture was stirred and dissolved at 40 ° C. After the gelatin is completely dissolved,
The temperature of the solution was lowered to 35 ° C. and 3.68 mmol of 4,
5,6-Triaminopyrimidine was added. Thereafter, a 30 cc aqueous solution containing 5.0 g of silver nitrate, and 30 cc containing 0.76 g of sodium chloride and 2.3 g of potassium bromide.
Was added at a constant flow rate for 45 seconds. Thereafter, the temperature of the reaction solution was raised to 75 ° C. for 20 minutes, and then aging was performed at this temperature for 15 minutes. Subsequently, 96 cc of an aqueous solution containing 16.32 g of silver nitrate and 96 cc of an aqueous solution containing 1.64 g of sodium chloride, 4.75 g of potassium bromide, and 0.35 g of potassium iodide were added at a constant flow rate for 20 minutes. Thereafter, the mixture was stirred for 5 minutes, and then an aqueous solution 40 containing 68 g of silver nitrate was added.
0 cc, and 400 cc of an aqueous solution containing 14.64 g of sodium chloride and 29.8 g of potassium bromide were added in 45 minutes, accelerating the flow rate so that the final flow rate at the end of this segment was about 5 times the starting flow rate. To obtain silver chloroiodobromide tabular grains. Thereafter, the resulting emulsion is subjected to coagulation washing, and pH and p
Br was adjusted to conserved values of 6 and 3.0, respectively. Tabular grains accounted for more than 99.0% of total grain projected area. The average ECD of the emulsions was 1.79 μm and their COV was 27%. The average thickness of the grains was measured in the same manner as in Emulsion A. The average thickness was 0.152.
μm (aspect ratio 11.8).

Emulsion C: Silver chloroiodobromide epitaxial tabular emulsion (this invention) Emulsion C was prepared by performing the following operations on Emulsion B described above.

0.5 mol of an emulsion sample was melted at 40 ° C.
By simultaneously adding the gNO ₃ solution and the KI solution, pB
r was adjusted to about 4. At this time, the AgNO ₃ solution and KI
The solution contains 12 ml of silver halide which precipitates in small amounts during this preparation.
% I. Next, 2M% NaCl
After the addition (based on the initial amount of silver iodobromide host), the following spectral sensitizing dye 1, spectral sensitizing dye 2 and spectral sensitizing dye 3 were added such that the total coverage was about 70%: 1: 1
And then 6M% by double jet addition balanced with AgNO ₃ solution and NaCl solution.
This operation of forming the AgCl epitaxy resulted in epitaxy growth occurring mainly at the corners and edges of the host tabular grains.

[0048]

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Emulsion D: silver chloroiodobromide tabular emulsion (comparative) 10 g of lime-processed bone gelatin and Na in a vessel equipped with a stirrer
5.5 g of Cl, defoamer, 2500 cc of pure water, and 40
A sufficient amount of sulfuric acid was added to adjust the pH to 5.0 at 0 ° C, and the mixture was stirred and dissolved at 40 ° C. After the gelatin was completely dissolved, the temperature of the solution was reduced to 35 ° C. and 3.68 mmol of 4,5,6-triaminopyrimidine was added. Thereafter, a 30 cc aqueous solution containing 5.0 g of silver nitrate, and 3 containing 0.38 g of sodium chloride and 3.06 g of potassium bromide.
0 cc of the solution was added at a constant flow rate for 45 seconds. Then 2
The reaction solution was heated to 75 ° C. in 0 minutes, and then ripened at this temperature for 15 minutes. Subsequently, 96 cc of an aqueous solution containing 16.32 g of silver nitrate, 0.82 g of sodium chloride, 6.42 g of potassium bromide and 0.35 g of potassium iodide
Was added at a constant flow rate for 20 minutes.

Thereafter, the mixture was stirred for 5 minutes, and then 68 g of silver nitrate
400 cc of an aqueous solution containing sodium chloride and 7.3
400 g of an aqueous solution containing 2 g and 39.73 g of potassium bromide
c was accelerated so that the final flow rate at the end of this segment was about 5 times that at the start, and added over 45 minutes to obtain silver chloroiodobromide tabular grains. Thereafter, the resulting emulsion was subjected to coagulation washing, and the pH and pBr were adjusted to storage values of 6 and 3.0, respectively. Tabular grains accounted for more than 99.5% of total grain projected area. The average ECD of the emulsion is 1.85μ
m and their COV was 25%. The average thickness of the grains was measured in the same manner as in Emulsion A, and as a result, the average thickness was 0.143 μm (aspect ratio: 12.3 μm).
9).

Emulsion E: silver chlorobromide epitaxial tabular grains (comparative) Emulsion D was subjected to epitaxial formation in the same manner as emulsion C.

0.5 mol of an emulsion sample was melted at 40 ° C.
By simultaneously adding the gNO ₃ solution and the KI solution, pB
r was adjusted to about 4.

At this time, the AgNO ₃ solution and the KI solution are
A small amount of silver halide precipitated during this preparation was added at a ratio such that it was 12% I. Then, after addition of 2M% NaCl (based on the initial amount of silver iodobromide host), the above-mentioned spectral sensitizing dye 1, spectral sensitizing dye 2 and spectral sensitizing dye 3 were added to a total coverage of about 70%. , And then 6M% AgCl epitaxy was formed by double jet addition balanced with AgNO ₃ solution and NaCl solution. This operation resulted in epitaxy growth, mainly at the corners and edges of the host tabular grains.

The above emulsions A to E were subjected to a sensitizing operation as follows. For emulsions A, B, D, and E, 0.5 mol of an emulsion sample was melted at 40 ° C., and pBr was adjusted to about 4 by simultaneously adding an AgNO ₃ solution and a KI solution.

At this time, the AgNO ₃ solution and the KI solution are
A small amount of silver halide precipitated during this preparation was added at a ratio such that it was 12% I. Next, the spectral sensitizing dye 1, the spectral sensitizing dye 2, and the spectral sensitizing dye 3 were combined at a total coverage of about 70%.
% Was added at a ratio of 1: 1: 1. afterwards,
After optimal chemical sensitization by adding potassium thiocyanate, sodium thiosulfate and potassium chloroaurate, 4-hydroxy-6-methyl-1,3,3a, 7-tetraazaindene (TAI), -Phenyl-5-mercaptotetrazole (PMT) was added. After all components were added, the mixture was heated to 60 ° C. to complete sensitization, and after cooling, more PMT was added.

Emulsions C and E were optimally spectrally sensitized by adding spectral sensitizing dye 1, spectral sensitizing dye 2 and spectral sensitizing dye 3, and then thiocyanated in the same manner as described above. After optimal chemical sensitization by adding potassium acid, sodium thiosulfate and potassium chloroaurate, 4-hydroxy-6-
Methyl-1,3,3a, 7-tetraazaindene (TA
I), 1-phenyl-5-mercaptotetrazole (P
MT) was added. After all the ingredients have been added, the mixture is brought to 60
C. to complete the sensitization. After cooling, more PMT was added.

Preparation of Single Layer Sensitive Material Samples The sensitized emulsions A to E were respectively applied to a cellulose acetate film support coated with a gray silver antihalation layer, and the emulsion layers were coated with the following surfactant and bis It was overcoated with a 4.3 g / m ² gelatin layer containing (vinylsulfonyl) methane hardener (1.75% by weight based on total weight of gelatin). 0.646 gA of emulsion coating amount
g / m ² , and the following coupler 1 (0.5
g / m ^2), a coupler ² (0.13g / m 2), a surfactant and a total gelatin 1.08 g / m ² was also be included. Thus, single-layer light-sensitive material samples 1A to 1E were obtained for emulsions A to E, respectively.

[0058]

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Evaluation Each of the samples 1A to 1E thus obtained was exposed to a wedge with white light for 0.01 second, developed in accordance with the following processing steps, and then subjected to an optical densitometer (Ponica manufactured by Konica Corporation).
DA-65) was used to measure the sensitivity and fog. Table 2 shows the relative sensitivity and fog when the sensitivity of Sample 1A was set to 100.

[0060]

[Table 1]

The composition of the developing solution is shown below.

Color developing solution Pure water 800 ml Triethylenediamine 2 g Diethylene glycol 10 g Potassium bromide 0.01 g Potassium chloride 3.5 g Potassium sulfite 0.25 g N-ethyl-N- (β-methanesulfonamidoethyl) -3-methyl-4- 1. Aminoaniline sulfate 6.0 g N, N-diethylhydroxylamine 6.8 g Triethanolamine 10.0 g Diethylenetriaminepentaacetic acid pentasodium salt 2.0 g Fluorescent brightener (4,4'-diaminostilbene disulfonic acid derivative) 0 g Potassium carbonate 30 g Water is added to bring the total volume to 1 liter, and the pH is adjusted to 10.10.

Bleaching / fixing solution Ferric ammonium diethylenetriaminepentaacetate dihydrate 65 g Diethylenetriaminepentaacetic acid 3 g Ammonium thiosulfate (70% aqueous solution) 100 ml 2-amino-5-mercapto-1,3,4-thiadiazole 2.0 g ammonium sulfite ( (40% aqueous solution) 27.5 ml Add water to make the total volume 1 liter, and adjust the pH to 5.0 with potassium carbonate or glacial acetic acid.

Stabilizing solution o-phenylphenol 1.0 g 5-chloro-2-methyl-4-isothiazolin-3-one 0.02 g 2-methyl-4-isothiazolin-3-one 0.02 g diethylene glycol 1.0 g fluorescence Brightener (Tinopearl SFP) 2.0 g 1-hydroxyethylidene-1,1-diphosphonic acid 1.8 g Bismuth chloride (45% aqueous solution) 0.65 g Magnesium sulfate heptahydrate 0.2 g PVP 1.0 g ammonia water ( (25% aqueous solution of ammonium hydroxide) 2.5 g Nitrilotriacetic acid / trisodium salt 1.5 g Add water to make the total volume 1 liter, and adjust the pH to 7.5 with sulfuric acid or aqueous ammonia.

Evaluation of Developability Each of the single layer samples 21 to 26 produced in the same manner as above was subjected to wedge exposure with white light for 0.01 second, and color development was carried out in accordance with the above-mentioned processing steps. ,
Samples having different development times were prepared, and each was evaluated by relative sensitivity when the sensitivity of the standard development time (3 minutes 15 seconds) of Sample 1A was set to 100. The results are shown in Tables 2 and 3.

[0066]

[Table 2]

[0067]

[Table 3]

As is clear from Tables 2 and 3, Sample 1C of the present invention is an emulsion having sensitivity / fog performance equal to or higher than that of tabular silver iodobromide grains and excellent processing speed. Recognize.

Example 2 Emulsion F: silver chloroiodobromide tabular emulsion (comparative) 3.75 lime-processed bone gelatin was placed in a container equipped with a stirrer.
g, KBr 4.76 g, defoamer and pH at 39 ° C.
Sufficient sulfuric acid to adjust to 8 and 6 liters of water were added. AgNO ₃ solution and halide (KBr, K
I and 98.5 M% and 1.5 M%, respectively, in a solution (both 2.5 M) in a quantity sufficient to produce 0.01335 mol of silver iodobromide, achieved by simultaneous addition. During the nucleation performed, the pBr and pH were almost maintained at the values initially set in the solution in the reactor. Following nucleation, Oxone ™ (2KHSO ₅ .KHSO ₄
・ K ₂ SO ₄ Aldrich (128mg) in water 20c
The gelatin in the reactor was rapidly oxidized by adding a solution dissolved in c, and the temperature was raised to 54 ° C. in 9 minutes. After keeping the reactor and its contents at this temperature for 9 minutes, a solution prepared by dissolving 100 g of methionine oxidized lime-processed bone gelatin and 90 mmol of 4,5,6-triaminopyrimidine in 1.5 l of water at 54 ° C. To the reactor.

Next, the pH was raised to 5.90 and 1M
122.5 cc of NaCl was added to the reactor. 24.5 minutes after nucleation, the growth phase begins, during which 2.5M
AgNO ₃ , 2.8M aqueous halogen salt solution (60M% and 40M% KBr and NaCl, respectively) and pBr in the reactor until 0.848 moles of silver chlorobromide were formed before the nucleation and growth started. Was added in proportion to maintain the value obtained by the addition of KBr (53.
33 minutes, constant flow).

Thereafter, the excess Cl ^- concentration was increased by adding a 1 M NaCl solution, followed by a 2.5 M AgN
O ₃ , 2.8M halogen salt aqueous solution (KBr and NaCl
Was restarted (60 M% and 40 M%, respectively) (additional flow rate was accelerated, segment initial flow rate: segment final flow rate = 1: 12.6).

[0072] were introduced K ₂ IrCl ₆ in an amount per mole of silver 0.04mg to form an emulsion without interrupting the addition of silver and halide after the introduction of 70% of total silver as an aqueous solution. As a result, a total of 9 mol of silver chloroiodobromide was produced.

When the addition was complete, the resulting emulsion layer was coherently washed and the pBr was adjusted to storage values of 6 and 2.5, respectively. The obtained emulsion was examined in the same manner as in Emulsion A. Tabular grains accounted for more than 99.0% of total grain projected area. The average ECD of the emulsion grains is 1.91.
μm and their COV was 41.

Since tabular grains account for almost all of the grains present, the average grain thickness was measured using the dye adsorption method as described for Emulsion A. The average thickness of the emulsion grains determined from the dye adsorption measurement was 0.068 μm.

Emulsion G: Silver chloroiodobromide epitaxial tabular emulsion (the present invention) After the same adjustments as in Emulsion F up to the formation of host grains, epitaxial formation was carried out in the same manner as in Emulsion C in Example 1. Finally, an emulsion G was obtained.

Emulsion H: Metal-doped silver chlorobromide epitaxial tabular emulsion (the present invention) After the same adjustments as in Emulsion F were performed up to the formation of host grains, epitaxial formation was performed in the same manner as in Emulsion G. However, during epitaxial formation, K ₄ Ru (C) was used in an amount of 30.0 mg / Ag mole based on silver in the host emulsion.
N) ₆ was added.

A single-layer light-sensitive material sample was prepared for emulsions F to H in the same manner as in Example 1, and thus obtained samples 2F to 2F were prepared.
Each 2H was exposed to wedges with white light for 0.01 second, developed in accordance with the same processing steps as in Example 1, and then subjected to sensitivity and fogging using an optical densitometer (PDA-65, manufactured by Konica Corporation). Was measured. Set the sensitivity of sample 2F to 10
Table 4 shows the relative sensitivities and fog when the values were set to 0.

[0078]

[Table 4]

As is clear from Table 4, the sample 2G of the present invention
Has excellent sensitivity fogging property as compared with 2F having no epitaxial layer, and the sample 2H obtained by adding a dopant to the epitaxial portion has higher sensitivity.

[0080]

The silver halide emulsion according to the present invention has improved sensitivity and granularity equivalent to silver iodobromide, is excellent in rapid processing properties, and changes in performance even when stored in a high humidity environment. It has an excellent effect of less.

Claims (2)

[Claims] 1. A dispersion medium having a (111) main surface, having an aspect ratio of 2 or more with respect to silver, and having a total grain projected area of 9
Occupies more than 0%, has an average equivalent circular diameter of at least 0.7 μm, an average thickness of less than 0.3 μm,
Having a latent image-forming chemically sensitized site on the surface of the tabular grains,
A silver halide photographic emulsion containing a silver halide grain containing a tabular grain and a spectral sensitizing dye adsorbed on the surface of the tabular grain, wherein the latent image-forming chemically sensitized site contains the tabular grain. Comprising a rock salt type face-centered cubic crystal lattice structure that forms an epitaxial junction with the silver halide projections, the projections being the (1) of the tabular grains.
11) A silver halide photographic emulsion comprising less than 50% of the main surface, wherein the projections are limited to tabular grains arranged closest to the peripheral edge of the tabular grains. 2. The method according to claim 1, wherein the protrusion has at least one kind of ligand having a higher electron-withdrawing property than fluoride ions, Fe ²⁺ , and Os.
²⁺ , Ru ²⁺ , Co ²⁺ , Rh ³⁺ , Ir ³⁺ , Pd ⁴⁺ or Pt
2. The silver halide photographic emulsion according to claim 1, further comprising a divalent Group VIII dopant selected from ⁴⁺ .