Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1998-12-22
2003-04-29
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S569000, C430S600000, C430S605000
Reexamination Certificate
active
06555307
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a silver halide photographic emulsion and a silver halide photographic light-sensitive material and, more particularly, to a silver halide photographic emulsion with high sensitivity and high graininess and a silver halide photographic light-sensitive material containing the emulsion.
Methods of manufacturing and techniques of using tabular silver halide grains are already disclosed in, e.g., U.S. Pat. No. 4,434,226, U.S. Pat. No. 4,439,520, U.S. Pat. No. 4,414,310, U.S. Pat. No. 4,433,048, U.S. Pat. No. 4,414,306, and U.S. Pat. No. 4,459,353. Advantages such as improvement of the sensitivity/graininess relationship including improvement of the sensitization efficiency obtained by spectral sensitizing dyes are known.
Extensive research has been done to use tabular grains having these advantages in a large size region greatly contributing to the performance of color negative sensitive materials.
Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) 63-220238 has disclosed a technique of increasing the sensitivity and improving the resistance to pressure by introducing dislocations.
Also, as a technique of using metal compounds, U.S. Pat. No. 5,576,172 has disclosed a method of increasing the sensitivity and improving the low illumination intensity failure by using both of group VIII elements and Ir element.
Unfortunately, small formatting of color negative films has advanced as shown in the APS format, so demands on improved image quality cannot be satisfied even by the use of these conventional techniques. Accordingly, a technique of further improving the sensitivity has been desired.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a silver halide photographic emulsion with high sensitivity and high graininess and a silver halide photographic light-sensitive material containing the emulsion.
DETAILED DESCRIPTION OF THE INVENTION
(1) A silver halide photographic emulsion in which tabular grains having an equivalent-circle diameter of 0.6 &mgr;m or more, a thickness of 0.3 &mgr;m or less, and an aspect ratio of 2 or more account for 70% or more (in number), wherein each of the tabular grains has a multilayered structure including two or more layers, at least one of the layers contains 1 to 20 mol % of a chloride with respect to the amount of silver forming the layer and each of the tabular grains contain a metal complex represented by formula (C-1) or (C-2) below:
[M
1
(CN)
6-a
L
a
]
n
(C-1)
[M
2
(CN)
4-b
L
b
]
m
(C-2)
wherein
M
1
: Fe, Ru, Re, Os, Ir, or Pt
M
2
: Pt or Au
L: a ligand except for CN
a: 0, 1, or 2
b: 0, 1, or 2
n: 2-, 3-, or 4-
m: 1- or 2-;
(2) The silver halide photographic emulsion described in item (1) above, wherein dislocation lines are observed in 80% or more (in number) of the tabular grains;
(3) The silver halide photographic emulsion described in item (2) above, wherein the variation coefficient of the equivalent-circle diameters of the tabular grains is 25% or less;
(4) The silver halide photographic emulsion described in any one of items (1) to (3) above, wherein the average aspect ratio of the tabular grains is 8 or more; and
(5) A silver halide photographic light-sensitive material having one or more silver halide emulsion layers on a support, wherein at least one of the emulsion layers contains the silver halide photographic emulsion described in any one of items (1) to (4) above.
The present invention will be described in detail below.
The emulsion of the present invention contains 70% or more (in number) of tabular silver halide grains having an equivalent-circle diameter of 0.6 &mgr;m or more. A “tabular silver halide grain” is a general term of grains having one twin plane or two or more parallel twin planes or grains which have no twin planes and principally have (110) main surfaces. A “twin plane” is a (111) plane on both sides of which all ions at lattice points have a mirror image relationship to each other. When this tabular grain is viewed from the direction perpendicular to the main surface, it looks like a triangle, a square, a hexagon, or a form obtained from a triangle, a square or a hexagon by making each corner thereof roundish. These triangular, square, hexagonal, and circular grains have parallel triangular, square, hexagonal, and circular main surfaces, respectively.
In the present invention, an equivalent-circle diameter is the diameter of a circle having the same area as the projected area of the parallel main surfaces of a grain.
The projected area of a grain can be obtained by measuring the area on an electron micrograph and correcting the magnification.
The thickness of a grain can be easily measured by obliquely depositing a metal on a grain, together with a latex as a reference, measuring the length of the shadow of the latex and the grain in an electron micrograph, and calculating by referring to the length of the shadow of the latex.
In the present invention, the aspect ratio of a tabular grain is the value obtained by dividing the equivalent-circle diameter by the grain thickness. The average aspect ratio is the average value of the aspect ratios of 1,000 or more grains in an emulsion.
The equivalent-circle diameter of each of the tabular grains occupying 70% or more of all the grains in the emulsion of the present invention is preferably 0.6 &mgr;m or more, more preferably 0.6 to 5.0 &mgr;m, and most preferably 0.8 to 3.0 &mgr;m.
The thickness of each of the tabular grains occupying 70% or more of all the grains in the emulsion of the present invention is preferably 0.03 to 0.3 &mgr;m, more preferably 0.03 to 0.25 &mgr;m, and most preferably 0.05 to 0.20 &mgr;m.
The average aspect ratio of each of the tabular grains occupying 70% or more of all the grains in the emulsion of the present invention is 2 or more, preferably 8 to 50, more preferably 8 to 40, and most preferably 8 to 30.
Each of the tabular grains used in the present invention has a multilayered structure including two or more layers, i.e., so to call a core/shell structure. Portions of a grain having different halogen compositions are called “layers”. For example, a grain composed of a portion having an iodide content of 20 mol %, i.e., core portion, and a portion having an iodide content of 5 mol %, i.e., a first shell, has a two-layered structure.
Each of the tabular grains used in the present invention has at least one layer containing 1 to 20 mol % of a chloride with respect to the silver amount of the layer. The chloride content is more preferably 1 to 15 mol %, and most preferably 3 to 10 mol %.
When a chloride is contained in at least one layer, the rest of the halogen composition in the layer can have arbitrary bromide and/or iodide content. However, the iodide content is preferably 0 to 35 mol %, more preferably 1 to 20 mol %, and most preferably 2 to 10 mol %.
The composition of each of the tabular grains used in the invention can be silver chlorobromide, silver chloroiodide or silver chloroiodobromide. The chloride content of the silver halides is 0.1 to 10 mol %, preferably 0.1 to 5 mol %, and most preferably 0.1 to 3 mol %. The silver iodide content of the silver halides, if any, is 0.1 to 20 mol %, preferably 0.1 to 15 mol %, and most preferably 0.1 to 10 mol %.
The halogen composition structure of a tabular grain used in the present invention can be checked by combining, e.g., X-ray diffraction, a transmission analytical electron microscope (analytical TEM), EPMA (also called XMA; a method of scanning a silver halide grain by electron rays to detect its silver halide composition), and ESCA (also called XPS; a method of radiating X-rays to spectroscopically detect photoelectrons emitted from the surface of a grain).
The relative standard deviation of the inter-grain silver iodide distribution and silver chloride distribution of a silver halide emulsion of the present invention is not particularly restricted. However, this relative standard deviation is preferably 50% or less, more pref
Baxter Janet
Birch & Stewart Kolasch & Birch, LLP
Fuji Photo Film Co. , Ltd.
Walke Amanda C.
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