Silver halide photosensitive material

Details Silver halide photosensitive material Silver halide photosensitive material

2003-03-10

2004-02-03

Schilling, Richard L. (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Radiation sensitive product

Silver compound sensitizer containing

C430S599000, C430S600000, C430S603000, C430S607000, C430S613000, C430S955000

Reexamination Certificate

active

06686140

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2002-67259, filed Mar. 12, 2002; No. 2003-22480, filed Jan. 30, 2003, the entire contents of both of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silver halide photosensitive material. Particularly, the present invention relates to a silver halide photosensitive material that reconciles high photographic speed and low fog.
2. Description of the Related Art
The silver halide photosensitive material principally comprises a support and, superimposed thereon, a dispersion medium containing lightsensitive silver halide grains. Extensive investigations have been conducted for increasing the photographic speed of silver halide lightsensitive material. Increasing the inherent sensitivity of silver halide grains is very important for attaining an increase of the photographic speed of silver halide lightsensitive material. Various methods have been employed for increasing the inherent sensitivity of silver halides with respect to such silver halide grains.
For example, there have been employed a sensitivity enhancement wherein use is made of a chemical sensitizer such as sulfur, gold or a compound of a metal of Group VIII, a sensitivity enhancement wherein a chemical sensitizer such as sulfur, gold or a compound of a metal of Group VIII is used in combination with an additive capable of intensifying the sensitizing effect thereof, and a sensitivity enhancement wherein use is made of an additive capable of exerting a sensitizing effect depending on silver halide emulsion species. Further, a method of conducting a reduction sensitization of silver halide grains has been employed as means for enhancing a photographic sensitivity.
Still further, recently, a sensitizing technology wherein use is made of an organic electron-donating compound having an electron-donating group and a split-off group has been reported (see, for example, U.S. Pat. No. (hereinafter also referred to as U.S. Pat. No.) 5,747,235 and U.S. Pat. No. 5,747,236; European Patent Publication No. (hereinafter also refereed to as EP) 786692A1, EP's 893731A1 and 893732A1; and U.S. Pat. No. 5,994,051). This is a novel sensitivity-enhancing technology and is effective for sensitivity enhancement.
However, the use of this organic electron-donating compound, although a sensitivity enhancement can be attained, is accompanied by an increase of fog (Dmin). Further, the use of this organic electron-donating compound has a drawback in that the storability would be deteriorated. Therefore, there has been a strong demand for improvement. For overcoming these problems, a joint use with a precursor type antifoggant (see, for example, U.S. Pat. No. 6,472,134B1) and a joint use with a storability improver (see, for example, EP 1227365A1 and Jpn. Pat. Appln. KOKAI No. (hereinafter also referred to as JP-A-) 11-119364 and JP-A-2001-42466) have been studied and improvement thereby has been attempted. However, the attained improvement is still unsatisfactory, and a further improvement is desired.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to solve the above problems of the prior art. Specifically, it is an object of the present invention to provide a silver halide photosensitive material of high speed and low fog. That is, the present invention is intended to not only attain a sensitivity enhancement by the use of a novel organic electron-donating compound, of tabular grains of high aspect ratio and large size by the use of a novel organic electron-donating compound but also reduce the fog at fresh and the fog after storage by the use of specific reducing compounds in combination.
The objects of the present invention have been attained by the following means.
(1) A silver halide photosensitive material comprising at least one light sensitive silver halide emulsion layer on a support, wherein the silver halide photosensitive material contains:
at least one compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, wherein the one-electron oxidation product is capable of releasing further one or more electrons, and
at least one reducing compound having a C/H value of 3 or less, and another reducing compound having a C/H value of more than 3, wherein the C/H value represents a ratio of (the number of Group IV elements)/(the sum of Groups III, V, VI and VII elements).
(2) A silver halide photosensitive material comprising at least one light sensitive silver halide emulsion layer on a support, wherein the silver halide photosensitive material contains:
at least one compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, wherein the one-electron oxidation product is capable of releasing further one or more electrons, and
at least one reducing compound having a molecular weight of 300 or less, and another reducing compound having a molecular weight of more than 300.
(3) The silver halide photosensitive material according to (1) or (2), wherein the one-electron oxidation product generated by one-electron oxidation, is capable of releasing further two or more electrons.
(4) The silver halide photosensitive material according to any one of (1) to (3), wherein the compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, wherein the one-electron oxidation product is capable of releasing further one or more electrons, is selected from the following compounds of types 1 to 5:
(Type 1)
A compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, wherein the one-electron oxidation product is capable of releasing further two or more electrons accompanying a subsequent bond cleavage reaction;
(Type 2)
A compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, wherein the one-electron oxidation product is capable of releasing further one electron accompanying a subsequent bond cleavage reaction, and the compound has, in its molecule, two or more groups adsorptive to silver halide;
(Type 3)
A compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, wherein the one-electron oxidation product is capable of releasing further one or more electrons after going through a subsequent bond forming process;
(Type 4)
A compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, wherein the one-electron oxidation product is capable of releasing further one or more electrons after going through a subsequent intramolecular ring cleavage reaction; and
(Type 5)
A compound having a formula: X—Y wherein X represents a reducing group, and Y represents a splitting-off group, wherein the reducing group represented by X is capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, from which Y is split accompanying a subsequent cleavage reaction of X—Y bond to thereby form an X radical, the X radical capable of further releasing one electron.
(5) The silver halide photosensitive material according to any one of (1) to (4), wherein the compounds of types 1 to 5 are represented by the following general formula (A), general formula (B), general formula (1), general formula (2), general formula (3), general formula (C), general formula (D), general formula (E), general formula (F) or general formula (G):
In the general formula (A), RED
11
represents a one-electron oxidizable reducing group; L
11
represents a split-off group; R
112
represents a hydrogen atom or substituent; and R
111
represents a nonmetallic atomic group capable of forming, together with carbon atom (C) and RED
11
, a specific 5- or 6-membered cyclic structure, wherein the 5- or 6-membered cyclic structure means a tetrahy

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