Radiation imagery chemistry: process – composition – or product th – Retrieving image made using radiation imagery
Reexamination Certificate
2001-08-16
2003-02-11
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Retrieving image made using radiation imagery
C430S350000, C430S505000, C430S554000, C430S558000, C430S566000, C430S959000
Reexamination Certificate
active
06517981
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a color photothermographic element comprising a hue-shifting phenylenediamine developing agent, or precursor thereof, in reaction association with a pyrazolone coupler for forming a cyan imaging dye.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,756,269 to Ishikawa et al. discloses the combination of three different developers with three different couplers. For example, a coupler “Y-1” is used with a hydrazide developing agent to form a yellow dye. Ishikawa et al. does not mention, nor attach any significance to, the fact that the same coupler is a magenta dye-forming coupler if used with a common phenylenediamine developing agent.
Clarke et al., in U.S. Pat. Nos. 5,415,981 and 5,248,739, showed that azo dyes formed from a blocked hydrazide developer are shifted to shorter wavelengths. This is perhaps not surprising since azo dyes derived from “magenta couplers” are known to be typically yellow and are used as masking couplers. The substitution pattern on the masking coupler is such that it can undergo further reaction with the oxidixed form of a paraphenylene diamine developer to form a magenta dye.
R. L. Bent et al., in
Photographic Science and Engineering
, Vol. 8, No. 3, May-June 1964 disclosed that the frequencies of maximum absorption of various dyes derived from p-phenylenediamines are closely related to the half-wave oxidation potentials of the compounds. As one point on various plotted correlations, experimental Compound A is disclosed (in Table II), in a 4-amino-N,N-dialkylaniline structure has 3,5-di-CH
3
substitution. The compounds are not disclosed as having any commercial utility and the reference might be construed as teaching that the use of Compound A would not be useful, since it would not provide the desired magenta hue with a conventional magenta coupler.
Japanese kokai JP 10090854 (1996) teaches different developers in the same color unit layer (having spectral sensitivity in the same wavelength range) in a photothermographic imaging element, in order to obtain better image or tone gradation.
U.S. Pat. No. 6,197,722 B1 to Irving et al. teaches a method of imaging, useful comprising providing an imaging member having at least one light insensitive layer comprising a catalytic center and multifunctional dye forming coupler, imagewise applying distinct developer solutions that will react with the multifunctional dye forming coupler to produce dyes of different colors. A preferred method of imagewise application of developer solution is by the technique known as “ink jet.”
PROBLEM TO BE SOLVED BY THE PRESENT INVENTION
Light-sensitive imaging elements which form yellow, magenta and cyan dye records of comparable density-forming ability and consistent stability in all three color records using conventional developers can be difficult. Cyan and yellow dye records can be a problem in this regard, especially in photothermographic elements. Accordingly, alternative ways of forming cyan or yellow dyes are especially useful in such imaging elements.
Another problem with conventional cyan dye-forming couplers relates to the fact that the raw stock stability of photographic elements is influenced by the physical properties of materials employed to formulate that element. Cyan dye-forming couplers are particularly prone to crystallization on extended cold keeping. This crystallization both degrades the image-forming ability of such an element and mars the appearance of images produced in such an element. This problem can be particularly acute in photothermographic or heat developable elements since it may be desirable to keep these elements cold before use, in order to prevent premature reaction.
SUMMARY OF THE INVENTION
It has been found advantageous to use a pyrazalone type of dye-forming coupler in the cyan record of a photothermographic element, in association with a para-phenylene diamine developer containing a substituent in both the 2- and 6-positions (ortho, ortho') relative to the coupling nitrogen. Such developers when oxidized yield cyan dyes with these couplers. With more conventional developers, these same couplers yield a magenta hue rather than a cyan hue. Moreover, pyrazolone couplers have been found to exhibit excellent reactivity in color photothernographic systems. Thus, according to the present invention, the superior characteristics of the pyrazolone couplers and the dyes formed therefrom can be utilized in the cyan layer.
Further, this invention describes the use of these pyrazolone 10 couplers in combination with the appropriate developers, blocked or unblocked, in a thermally-processable system or other incorporated-developer photographic element. In one embodiment, improved properties have been obtained when, according to the present invention, the dye-forming coupler and blocked developer according to the present invention, a cyan dye is formed in a thermally-processed film. In particular, a surprising and significant increase in maximum density (Dmax) is obtained with only minor increases in Dmin, compared to the use of a commonly employed cyan dye-forming coupler with a conventional blocked conventional developer.
DETAILED DESCRIPTION OF THE INVENTION
As mentioned above, the invention relates to a light-sensitive color photographic imaging element comprising, in reactive association, a pyrazolone coupler and a “developer precursor” that liberates a developing agent enabling cyan color from the coupler on development. In particular, a “typically magenta pyrazolone dye-forming coupler” is used in the cyan dye-forming record by rendering the hue of the resultant dye a cyan hue. In one embodiment, this is accomplished by using a para-phenylene diamine developer containing substituents, preferably a methyl group, in both the 2- and 6-positions (ortho, ortho') relative to the coupling nitrogen along with selected magenta dye-forming couplers. By the term “typically magenta dye-forming coupler” is meant that the coupler forms a magenta dye with an oxidized form of the conventional developer 4-(N-ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine.
In one embodiment, the coupler-developer combination according to the present invention, in which the developer is blocked or otherwise a developer precursor, is used in a thermally-processable system or other incorporated-developer photographic element where the incorporated developer chosen for each color-forming record need not be identical in structure, but are chosen to utilize the optimal developer-coupler combination. Thus, the invention encompasses the possible use of a one or more different couplers (preferably at least two) and one or more different developing agents (preferably at least two). There can be one, two, or three different couplers in the same imaging element. It is possible to have more than three couplers, for example, per the Japanese kokai mentioned above. It is also possible to have more than three different developers (or blocked developers), three different developers (or blocked developers), two different developers (or blocked developers), or a single developer (or blocked developer).
In a preferred variant, the element is a photothermographic element that is dry developed by heat treatment. In another variant, an imagewise exposed photothermographic element is developed by treatment with both heat and chemical base or acid, either by contacting the element to a pH controlling solution or by contacting the element to a pH controlling laminate.
When the formed image is intended for human viewing, a first blocked coupling developer is cyan dye forming, a second blocked coupling developer is magenta dye forming, and a third blocked coupling developer is yellow dye forming. Preferably, the pyrazolone coupler is present, in reactive association, with a blocked developer, in the red-light-sensitive color layer unit. However, if the formed image is to be scanned, it is possible to produce other colored dyes.
Preferably, the imaging element comprises a blocked form of a developer that results in a cyan dye being forme
Olson Leif P.
Reynolds James H.
Slusarek Wojciech K.
Szajewski Richard P.
Chea Thorl
Konkol Chris P.
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