Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-03-08
2003-10-21
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S567000, C430S607000, C430S611000, C430S600000, C430S604000
Reexamination Certificate
active
06635413
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-060628, filed Mar. 8, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a silver halide photographic emulsion. More particularly, the present invention relates to a tabular silver halide grain photographic emulsion which is excellent in photographic speed and graininess, ensures slight change of photographic performance after storage and also ensures less fog occurrence, and further relates to a process for producing the same and a silver halide photographic lightsensitive material containing the above emulsion.
Methods of converting, for example, tabular grains to those of a high aspect ratio or a monodispersion for enhancing the sensitivity/graininess ratio of silver halide photographic emulsion are well known to persons of ordinary skill in the art to which the invention pertains. Further, combining a monodisperse tabular material of high aspect ratio with selenium sensitization to thereby enable a sensitivity enhancement, as described in Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) 6-332093, is known. Still further, combining an emulsion having its intergranular iodine distribution regulated to a monodispersion with selenium sensitization to thereby enable a sensitivity enhancement, as described in JP-A-6-11782 and JP-A-9-15776, is known. However, the realized sensitivity is still unsatisfactory, and a further enhancement of sensitivity is desired. These patent application specifications, although describing the amount of added selenium sensitizer or gold sensitize, do not describe the substantial amount of selenium or gold contained in grains and fail to specify any substantial selenium/gold ratio. There is no precedent of performing a simultaneous control of the ratio of selenium/gold contained in grains. The inventors have first found in the investigations for the present invention that controlling the selenium/gold ratio within a specified range is important for attaining a sensitivity enhancement.
With respect to the silver halide photographic lightsensitive material, a high sensitivity is demanded. The degree of change of photographic performance by storage of a lightsensitive material after production tends to increase with the sensitivity enhancement. Consequently, it is demanded to suppress this, and especially a technology for suppressing fogging is required.
In this connection, adding a palladium compound such as a palladium complex of ethylenediamine in order to suppress fogging is disclosed in, for example, U.S. Pat. No. 2,552,229, U.S. Pat. No. 2,566,263 and JP-A-5-333480. This is practically effective in suppressing the fog increase during storage.
JP-A-8-234341 (U.S. Pat. No. 5,614,360) discloses that the use of a palladium compound of ethylenediamine is advantageous in that any viscosity increase does not occur even in high gelatin concentrations. However, when the storage is conducted under tropical conditions of high temperature and high humidity, the fog suppressing effect thereof is not satisfactory. Thus, further improvement is desired (with respect to the fog during storage under tropical conditions, data are available from U.S. Pat. No. 2,552,229).
In the investigations for the present invention, it was further found that the use of Pd complexes described in the above JP-A-8-234341 (U.S. Pat. No. 5,614,360) has a drawback in that the degree of change of photographic performance during running processing is increased. In the production of silver halide photographic lightsensitive material, it is also desired that the degree of change of photographic performance during running processing be slight. Therefore, there is a demand for simultaneously suppressing the change of photographic performance during storage and the change of photographic performance during running processing.
The inventors have found that these tasks can be attained by the use of a specified palladium complex according to the present invention. There is no precedent of disclosing the use of the specified palladium compound and no precedent of applying the same to the lightsensitive silver halide emulsion of the present invention.
On the other hand, the use of a mercaptotetrazole compound having a water-soluble group in order to suppress the fogging during storage is described in JP-A-4-16838. It is disclosed to achieve a shelf life prolongation by the use of a mercaptotetrazole compound in combination with a mercaptothiadiazole compound.
However, the prior art fails to disclose the use of the emulsion of the present invention {lightsensitive silver halide emulsion comprising silver halide grains, wherein at least 50% of the total projected area are occupied by tabular silver halide grains; an average iodine content of all the silver halide grains is at least 2 mol %; and the tabular silver halide grains have at least 10 dislocation lines per grain; which lightsensitive silver halide emulsion satisfies at least one selected from among requirements (1) and (2) set forth below; and has undergone such chemical sensitization that a selenium sensitizer is added in an amount of 2.5×10
−6
to 5×10
−5
mol/mol silver and has undergone spectral sensitization: (1) the emulsion is prepared by performing the spectral sensitization in which a spectral sensitizer is added in the presence of 50 ppm or less of calcium, magnesium and strontium; followed by adding at least one water-soluble salt of a metal selected from the group consisting of calcium, magnesium and strontium, so that the concentration of calcium, magnesium and strontium becomes 100-2500 ppm; and then the chemical sensitization is started, and (2) the chemical sensitization and the spectral sensitization are performed in the presence of an alkali treated bone gelatin containing components of at least 280 thousand molecular weight in an amount of at least 30% in a molecular weight distribution measured by the PAGI method} in combination with a water-soluble mercapto compound. Further, the prior art fails to disclose advantageous effects attained by the use of a water-soluble mercaptotetrazole and a water-soluble mercaptotriazole in the emulsion as conducted in the present invention.
Although the inventors investigated the use of various types of compounds known as a water-soluble mercapto compound in the above emulsion of high sensitivity/graininess ratio according to the present invention, most thereof suffered from a sensitivity decrease. Further extensive investigations have been conducted, and it has been found that the use of a specified combination, namely the use of a water-soluble mercaptotetrazole and a water-soluble mercaptotriazole in combination, enables attaining a shelf life prolongation without detriment to the sensitivity.
A thiocyanate ion is useful for producing an emulsion of high sensitivity. It is well known to persons of ordinary skill in the art to which the invention pertains that reducing the amount thereof invites a sensitivity decrease. However, there is no precedent of particularly teaching that, with respect to the above emulsion of the present invention, not only is the amount of thiocyanate ion needed lower than the hitherto known level but also a shelf life prolongation can be attained thereby.
Limiting a surface silver iodide content for the purpose of suppressing the fogging during aging is effective. However, there is no precedent of attempting to lower an extreme-surface silver iodide content by adding and dissolving silver iodobromide fine grains having a silver iodide content lower than the surface silver iodide content of host grains during the after-ripening.
Incorporating a metal complex having a cyan ligand in emulsion grains in order to enhance a quantum sensitivity is described in, for example, JP-A-4-306642. However, there is no description particularly teaching that not only can the sensitivi
Aida Shunichi
Inami Yoshiyasu
Sasaki Hirotomo
Takeuchi Hiroshi
Baxter Janet
Birch & Stewart Kolasch & Birch, LLP
Walke Amanda C.
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