Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2002-07-30
2004-02-10
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S566000, C430S572000, C430S576000, C430S578000, C430S580000, C430S581000, C430S583000, C430S592000, C430S595000, C430S603000, C430S955000
Reexamination Certificate
active
06689554
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2001-234048, filed Aug. 1, 2001; No. 2001-234075, filed Aug. 1, 2001; No. 2001-250679, filed Aug. 21, 2001; and No. 2001-272137, filed Sep. 7, 2001, the entire contents of all of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lightsensitive silver halide emulsion of enhanced photographic speed and a photographic element including the same.
2. Description of the Related Art
Various techniques are being employed for the purpose of improving the light sensitivity of silver halide photographic lightsensitive materials. For example, chemical sensitizers such as sulfur, gold and compounds of Group VIII metals are being employed in order to enhance the inherent photographic speed of silver halides. Spectral sensitization with the use of cyanines and other polymethine dyes is also a technology known in the art to which the present invention pertains.
The phenomenon that, when a spectral sensitizing dye is added to an emulsion in an amount exceeding the optimum amount thereof, the photographic speed of the emulsion is extremely reduced is known as a dye desensitization. As means for improving this phenomenon, there is known a technology comprising utilizing the supersensitization effect by the use of a supersensitizer. This supersensitizer is a generally colorless organic compound which itself does not exert any spectral sensitizing effect, but acts on a sensitizing dye (or excited sensitizing dye) to thereby exert an effect of inhibiting the dye desensitization.
Examples of supersensitizer compounds are listed in, for example, patents such as U.S. Pat. Nos. 2,937,089, 3,706,567, 2,875,058, 3,695,888, 3,457,078, 3,458,318, 3,615,632, 5,192,654, 5,306,612, 2,419,975, 5,459,052 and 4,971,890, and E.P. 554856.
Further, various electron-donating compounds are used in combination with the sensitizing dye in order to enhance the spectral sensitivity of silver halide photographic lightsensitive materials. Examples of electron-donating compounds are listed in U.S. Pat. Nos. 3,695,588 and 3,809,561, and GB's 255084 and 1064193.
Still further, use is made of compounds comprising such an electron-donating compound linked by a covalent bond with a sensitizing dye. Examples of these compounds are listed in U.S. Pat. Nos. 5,436,121 and 5,478,719 (compounds having an electron-donating styryl base bonded to a monomethine dye) and U.S. Pat. No. 4,607,006 (compounds having an electron-donating group derived from phenothiazine, phenoxazine, carbazole, dibenzophenothiazine, ferrocene or tris-2,2′-bipyridylruthenium, or having a triarylamine skeleton bonded to a silver halide adsorptive group).
However, an ideally enhanced photographic speed has not yet been realized despite implementation of the above various means proposed. In particular, the current situation is that there are few compounds which can attain an enhancement of photographic speed while coping with a problem of fog occurring in accordance with the enhancement of photographic speed or a problem of storage fogging experienced when silver halide photographic lightsensitive materials are stored under severe conditions, for example, high temperature and high humidity, or exposure to hazardous gas evolved at the time of combustion, such as automobile exhaust gas.
Recently, a technology of sensitizing with the use of a compound capable of being fragmented (bond cleavage) after a one-electron oxidation and further releasing another electron as a “two-electron sensitizer” has been reported in U.S. Pat. Nos. 5,747,235 and 5,747,236, E.P.'s 786692A1, 893731A1 and 893732A1, WO 99/05570, and paper published in Journal of American Chemical Society (“Two-Electron Sensitization: A New Concept for Silver Halide Photography”, J. Am. Chem. Soc., 122, 11934-11943 (2000)). This compound is described in patent specifications as being characterized in that it is oxidized by a dye hole (sensitizing dye molecule having lost one electron after injection of an electron into a conductive band of silver halide from an excited sensitizing dye) or a hole generated by excitation of silver halides, undergoes a fragmentation reaction and releases another electron to thereby induce an enhancement of photographic speed.
However, even the use of this compound has been unable to attain an ideal technology of enhancing photographic speed whereby a lightsensitive material of high speed/fog ratio and of excellent storability can be produced.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a silver halide photographic lightsensitive material which ensures enhanced photographic speed of a photographic emulsion and suppresses fog that is likely to occur in accordance with the enhancement of photographic speed, and which realizes a reduced fog increase even if stored under severe conditions, for example, high temperature and high humidity, or exposure to hazardous gas evolved at the time of combustion, such as automobile exhaust gas.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
The above object has been attained by the following constructions 1 to 10. Particularly, the use of the following novel type of electron-releasing compound has enabled attaining a silver halide emulsion and a silver halide photographic lightsensitive material which realize a high speed/fog ratio and excellent storability.
Construction 1: A silver halide emulsion comprising at least one compound selected from the following four types of electron-releasing compounds, namely:
(Type 1) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further two or more electrons accompanying a subsequent bond cleavage reaction;
(Type 2) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one electron accompanying a subsequent bond cleavage reaction, and the one-electron oxidation product having, in its molecule, two or more adsorptive groups acting on silver halides;
(Type 3) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one or more electrons after going through a subsequent bond forming process; and
(Type 4) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one or more electrons after going through a subsequent intramolecular ring cleavage reaction.
Construction 2: The silver halide emulsion according to construction 1, wherein the above at least one compound is a compound which undergoes a one-electron oxidation induced by exposure of the silver halide emulsion to light.
Construction 3: The silver halide emulsion according to construction 1 or 2, wherein the above at least one compound is represented by any of the following general formulae (A), (B), (C), (D), (E), (F), (1), (2) and (3):
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 a cyclic structure corresponding to a tetrahydro form, hexahydro form or octahydro form of a 5-membered or 6-membered aroma
Asanuma Naoki
Hoshimiya Takashi
Kyota Hirokazu
Mizuno Masafumi
Taniguchi Masahiko
Fuji Photo Film Co. , Ltd.
Schilling Richard L.
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