Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
1999-12-20
2003-07-15
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S467000, C430S469000, C430S599000, C430S600000, C430S603000, C430S607000, C430S611000, C430S613000, C430S583000
Reexamination Certificate
active
06593073
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the use of a fragmentable electron donor with core/shell, light-sensitive, silver halide emulsions.
BACKGROUND OF THE INVENTION
Core/shell bromoiodide emulsions containing high iodide regions have long been a staple of the blue-sensitive layer in color film. Their intrinsic light absorption in the blue region together with their low response to pressure, continue to make them an attractive choice, especially as the fast component. Recent techniques have been developed to improve the photographic performance of such emulsions by introducing twin planes (Maternaghan in U.S. Pat. No. 4,184,877), producing grains with a particular iodide architecture (Takada et al in U.S. Pat. No. 4,668,614, Ishikawa et al in U.S. Pat. No. 4,963,467), narrowing the range of iodide in individual grains (Shibahara et al in U.S. Pat. No. 4,728,602), and growing grains free of renucleation while obtaining a narrow distribution of grains with a high iodide content (Chang et al, U.S. Pat. No. 5,570,327). All of these methods suffer, however, from various disadvantages such as requiring a seed emulsion which has been previously prepared, producing a small yield of emulsion, or requiring excessive growth times. Furthermore, many of these emulsions derive increased photographic response from a narrow size distribution of grains which inherently leads to less latitude in response to light.
PROBLEM TO BE SOLVED BY THE INVENTION
There is, thus, a need for a readily prepared, high-iodide, core/shell emulsion of increased photographic response.
SUMMARY OF THE INVENTION
One aspect of this invention comprises a silver halide photographic element comprising at least one silver halide emulsion layer comprising core/shell silver halide grains wherein the core region comprises silver bromide with from about 5 to about 20% silver iodide and the shell region comprises silver bromide with about 0.1 to about 10% silver iodide and said layer contains a fragmentable electron donor compound of the formula X—Y′ or a compound which contains a moiety of the formula —X—Y′;
wherein
X is an electron donor moiety, Y′ is a leaving proton H or a leaving group Y, with the proviso that if Y′ is a proton, a base, &bgr;
−
, is covalently linked directly or indirectly to X, and wherein:
1) X—Y′ has an oxidation potential between 0 and about 1.4 V; and
2) the oxidized form of X—Y′ undergoes a bond cleavage reaction to give the radical X
•
and the leaving fragment Y′; and, optionally,
3) the radical X
•
has an oxidation potential≦−0.7V (that is, equal to or more negative than about −0.7V).
ADVANTAGEOUS EFFECT OF THE INVENTION
This invention provides a photographic element comprising a silver halide emulsion having a high intrinsic light absorption in the blue region with a low sensitivity to pressure and an increased photographic response. Further, the emulsion can be readily prepared without a seed emulsion and can be produced in high yield in a short time.
All percentages specified herein are mole %, unless indicated to the contrary.
DETAILED DESCRIPTION OF THE INVENTION
This invention also provides a high-iodide emulsion with increased photographic response which is especially useful in the blue record of color film. The enhanced speed of the emulsion induced by the fragmentable electron donor allows the use of an emulsion which is readily formed in good yield in a short run time without the need of nucleating seeds. Because the emulsion is, polydisperse it has a wide latitude allowing lower silver coverages in color film.
Useful emulsions in this application include bromide emulsions with core regions containing from 5-20% iodide. Especially useful are those emulsions with cores of from 8-18% iodide. The core is suitably 20-60% of the total grain volume. Especially useful are those with a core of 30-50%. The shell region can be 0-10% iodide but in all cases, the iodide in the shell is less than that in the core. Especially useful are emulsions with a shell comprising from 2-8% iodide. The total iodide of the emulsion can range from 2-15%. Iodide analysis can be performed using X-ray powder diffraction as described by Blanton in
Industrial Applications of X
-
Ray Diffraction
, Chapter 25, 1999.
Bromoiodide emulsions have been the mainstay of photographic films for many years. Illingsworth in U.S. Pat. No. 3,320,069 disclosed the utility of bromoiodide emulsions prepared in the presence of thiocyanate. The preferred embodiment is based on such an emulsion although the manner of thiocyanate addition is not critical and, in the present invention, the iodide architecture has been refined.
In the following discussion of silver halide emulsions and their preparation, reference will be made to
Research Disclosure
, September 1996, Number 389, Item 38957, which will be identified hereafter by the term “
Research Disclosure I
.” This and all other Research Disclosures referenced herein are published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire P010 7DQ, ENGLAND. The Sections hereafter referred to are Sections of the
Research Disclosure I
unless otherwise indicated.
The silver halide emulsions employed in the photographic elements of the present invention may be negative-working, such as surface-sensitive emulsions or unfogged internal latent image forming emulsions, or positive working emulsions of the internal latent image forming type (that are fogged during processing). Suitable emulsions and their preparation as well as methods of chemical and spectral sensitization are described in
Research Disclosure I
, Sections I through V. Color materials and development modifiers are described in Sections V through XX. Vehicles which can be used in the photographic elements are described in Section II, and various additives such as brighteners, antifoggants, stabilizers, light absorbing and scattering materials, hardeners, coating aids, plasticizers, lubricants and matting agents are described, for example, in Sections VI through XIII. Manufacturing methods are described in all of the sections, layer arrangements particularly in Section XI, exposure alternatives in Section XVI, and processing methods and agents in Sections XIX and XX.
With negative working silver halide a negative image can be formed. Optionally a positive (or reversal) image can be formed although a negative image is typically first formed.
The grain size of the core/shell silver halide may have any distribution known to be useful in photographic compositions.
The morphology of the core/shell silver halide may be octahedral, cubic, polymorphic, or tabular.
The silver halide grains to be used in the invention may be prepared according to methods known in the art, such as those described in
Research Disclosure I
and James,
The Theory of the Photographic Process
. These include methods such as ammoniacal emulsion making, neutral or acidic emulsion making, and others known in the art. These methods generally involve mixing a water soluble silver salt with a water soluble halide salt in the presence of a protective colloid, and controlling the temperature, pAg, pH values, etc, at suitable values during formation of the silver halide by precipitation.
In the course of grain precipitation one or more dopants (grain occlusions other than silver and halide) can be introduced to modify grain properties. For example, any of the various conventional dopants disclosed in
Research Disclosure I
, Section I. Emulsion grains and their preparation, sub-section G. Grain modifying conditions and adjustments, paragraphs (3), (4) and (5), can be present in the emulsions of the invention. In addition it is specifically contemplated to dope the grains with transition metal hexacoordination complexes containing one or more organic ligands, as taught by Olm et al U.S. Pat. No. 5,360,712, the disclosure of which is here incorporated by reference.
It is specifically contemplated to incorporate in the face centered cubic crystal lattice o
Chang Yun C.
Eikenberry Jon N.
Blank Lynne M.
Huff Mark F.
Walke Amanda C.
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