Textiles: cloth finishing – Miscellaneous
Reexamination Certificate
2001-12-19
2003-02-04
Letscher, Geraldine (Department: 1752)
Textiles: cloth finishing
Miscellaneous
C430S226000, C430S359000, C430S543000, C430S559000, C430S955000, C430S958000, C430S385000
Reexamination Certificate
active
06513212
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a scannable color photographic or photothermographic element containing a silver-halide emulsion layer and an associated high-dye-yield cyan coupler that releases a high extinction dye, for example methylene blue, in addition to the normal chromogenic dye during processing.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 4,840,884 to Mooberry and Singer disclose high-dye-yield (HDY) couplers that react with oxidized color developer, typically in a conventional wet, alkaline, photographic process, to form one dye from the coupler parent and release a second dye or a precursor of a second dye, usually a high extinction methine dye. Coupler coating loads can be decreased and/or density increases can be achieved by the use of such HDY couplers compared to ordinary two equivalent couplers for a given silver laydown. U.S. Pat. No. 5,457,004 describes high dye yield couplers, especially yellow couplers, that have methine dye chromophores and sulfonamide-solubilized coupler moieties. Improved high-dye-yield (HDY) couplers have been disclosed by Mooberry et al. in U.S. Pat. No. 6,132,944. This patent discloses high-dye-yield couplers that contain a release dye bonded through an acyloxy type group at the coupling site where the coupler contains an arylhydroxy, sulfamoyl or sulfonamido group of pKa less than 8.8.
PROBLEM TO BE SOLVED BY THE INVENTION
There is a continuing need for a coupler that (a) enables formation of increased dye density in the photographic element; (b) enables an increase in contrast, leading to improved images through use of higher concentrations of image modifying compounds in the photographic element; and (c) enables lower concentrations of silver halide in the photographic element without lowering image quality. Moreover, the use of higher-density forming couplers allow the laydown of couplers to be minimized, which improves image resolution.
Higher density can be achieved by increased reactivity and by an increased extinction of the dye formed or released by the coupler.
Another problem, especially relevant to photothermographic systems, is achieving adequate dye density, especially for cyan and yellow dyes. Photothermographic systems involve heat processable photosensitive elements that are constructed so that after exposure, they can be processed in a substantially dry state by applying heat. Because of the much greater challenges involved in developing a dry or substantially dry color photothermographic system, however, most of the activity to date has been limited to black and white photothermographic systems, especially in the areas of health imaging and microfiche.
Finally, another problem in constructing light-sensitive imaging elements is forming cyan, yellow and magenta dye records of comparable density-forming ability and consistent stability in all three color records, which can be especially difficult in a photothermographic system. A major problem that remains in phototothermographic systems, wherein the dye images require the reaction of a blocked developer and a dye-forming coupler through substantially dry gelatin, is how to facilitate the speed and ease with which the various dye images may be formed. In order to solve this problem, there is a need for a photothermographic element containing a stable high-dye-yield coupler that will exhibit a higher reactivity with oxidized developer than couplers heretofore discovered and provide higher extinction dyes.
SUMMARY OF THE INVENTION
These and other problems may be overcome by the practice of our invention. Applicants have found certain cyan HDY couplers that are advantageous for light-sensitive color photographic systems. In particular, Applicants have demonstrated that a class of cyan HDY couplers gives high dye densities with heat processing in the absence of base. More specifically, such couplers produce a second dye of high extinction coefficient such as methylene blue (extinction=100,000) in addition to the normal chromogenic dye (extinction about 30,000).
Preferably, the HDY couplers of the present invention form two dyes having a combined extinction that is greater than 1.5 times the extinction of the dye formed by the coupler alone.
The invention is especially useful for films intended for scanning or for use in color photothermographic films. First, achieving higher dye density is a greater problem in color photothermographic systems as explained above. Second, more variation in hue can be tolerated in a scan-only film.
In one embodiment, the HDY coupler is used to produce a cyan hue, for example, by releasing methylene blue or a similar dye. Methylene blue releasing HDY couplers can be readily synthesized from commercially available methylene blue by reduction, phosgenation, and attachment to appropriate coupler intermediates. In one embodiment, it has been found advantageous to use such an HDY cyan coupler in the cyan record of a photothermographic element, in association with a blocked para-phenylene diamine developer.
The invention is also directed to a photothermographic element containing a light sensitive silver halide emulsion layer having associated therewith a coupler represented by Formula I. The invention is also directed to a method of making HDY couplers according to the present invention.
The present invention requires coating at least one surface of a substrate with at least one compound represented by the following formula:
COUP—(T)
m
—L—DYE′ (I)
Wherein
COUP is a photographic coupler residue capable of coupling with oxidized color developer to form a first cyan dye;
T is a timing group;
m is an integer from 0 to 2, preferably 0 or 1;
L is a linking group selected from the group consisting of —OC(═O)—, —OC(═S)—, —SC(═O)—, and —SC(═S)— and
wherein DYE′ is a group that, upon release from the coupling site in COUP, forms a second dye (a “DYE compound”) or dye precursor (“P-DYE”) such as a leuco dye that is then converted to a second dye, which second dye is the same color (cyan) as the first dye. The coupler COUP is linked, at the coupling site, through an optional timing group and a linking group (preferably OC═O) to a nitrogen atom in the DYE′ group. In one embodiment, DYE′ is represented by the following formula:
wherein
R
2
and R
3
are independently selected organic or inorganic substituents selected to obtain a cyan hue in the DYE compound, which DYE compound absorbs predominantly in the 600 to 700 nm range. Preferably, R
2
and R
3
are C1 to C10 (has 1 to 10 carbon atoms) organic subsituents, more prefereably independently selected from the group consisting of substituted or unsubstituted alkyl, aryl, alkoxy, hydroxy, amino, alkylamino, dialkylamino, and acetamido groups, preferably having 1 to 10 carbon atoms, more preferably 1-6 carbon atoms; and wherein a plurality of organic R
2
or a plurality of organic R
3
groups can form a saturated, unsaturated, or aromatic ring, including carbocylic and heterocylic rings (preferably C1 to C10 rings). Preferably n and p are both 1 and R
2
and R
3
are para to the nitrogen in Structure II;
n and p are independently an integer from 0 to 4; and
Q is O, S, or NR′ where R′ is H or a substituted or unsubstituted alkyl or aryl group.
Finally, the invention also provides an imaging element and an imaging method. In one embodiment, a color phototothermographic element is exposed to light and thereafter heating the element for development.
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of the invention is directed to a chromogenic photothermographic element comprising radiation sensitive silver halide, a blocked developing agent, at least one cyan coupler that forms an image dye upon reaction of said compound with the oxidation product of the unblocked developing agent, a hydrophilic binder, wherein the cyan coupler provides improved density during image formation.
The color photothermographic element comprises a blocked developer that decomposes (i.e., unblocks) on thermal activation to release a d
Levy David H.
Mooberry Jared B.
Slusarek Wojciech K.
Southby David T.
Yang Xiqiang
Eastman Kodak Company
Konkol Chris P.
Letscher Geraldine
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