Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2001-05-31
2003-05-27
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S033000, C560S029000, C560S030000, C564S042000, C548S309700, C546S300000
Reexamination Certificate
active
06570034
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to novel blocked color developers for photographic imaging element. In particular, the blocked developer is a phenylenediamine developing agent that can be incorporated into the imaging element to produce a distinct color.
BACKGROUND OF THE INVENTION
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 “inkjet.”
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 correleations, 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.
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
The present invention relates to a novel blocked phenylenediamine developer useful, in reactive association, for enabling, on development, a non-magenta color, for example a cyan color, from a dye-forming coupler.
In one embodiment, the developer has the property that the dye color formed with the coupler is distinctly different from the color formed by the same coupler with an oxidized form of the conventional developer 4-(N-ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine. In one embodiment, the developer has the property that it is capable of forming a distinctly colored cyan dye with one coupler, while the same coupler forms a magenta dye with an oxidized form of the conventional developer 4-(N-ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine. The latter developer (also known as “CD2”), which developer is widely used, is used herein as a standard means for the purpose of enabling a convenient color comparison, but other developers could have been substituted instead.
In a first embodiment, a light-sensitive silver-halide color photographic element has a red-light-sensitive silver-halide layer unit and a first blocked coupling developer, a green-light-sensitive silver-halide layer unit and a second blocked coupling developer, and a blue-light-sensitive silver-halide layer unit having a third blocked coupling developer, wherein at least two of the first, second, and third blocked coupling developers are different and wherein at least one layer unit, or imaging layer in the layer unit, has a blocked developer according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
As mentioned above, the invention relates to novel blocked developer that can be used in a light-sensitive color photographic imaging element comprising at least one chromogenic coupler in reactive association with the blocked developer. In one embodiment, the blocked developer liberates a developing agent enabling cyan color from the coupler on development, wherein the same coupler forms at least one other distinctly colored dye with an oxidized form of the conventional developer 4-(N-ethyl-N-2-hydroxyethyl)-2-methylphenylenediamine. The blocked developer (or “developer precursor”) liberates a phenylenediamine type of developer as described in more detail below.
Thus, the developer according to the present invention can have a number of possible uses, including use in imaging elements having a number of different couplers and a number of different developing agents. There can be two different couplers or three different couplers in the imaging element. It is possible to have more than three couplers, 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 one embodiment, there are two different developers and three different couplers, which may minimize costs by not having more than two developers.
Thus, the developer can be employed in an imaging element comprising, for example, a red-light-sensitive layer unit, a green-light-sensitive layer unit and a blue-light-sensitive layer unit, wherein at least one layer in at least two different layer units has in reactive association an independently selected dye forming coupler and an independently selected blocked developer. Preferably, the blocked developer is different in two layer units. Alternatively, the imaging element can comprise a red-light-sensitive layer unit, a green-light-sensitive layer unit and a blue-light-sensitive layer unit, wherein all three layer units have in reactive association an independently selected dye forming coupler and an independently selected blocked developer, wherein the dye coupler is different in each layer unit and the developing agent is the same in two layer units. As a further alternative, the element can comprises a red-light-sensitive layer unit, a green-light-sensitive layer unit and a blue-light-sensitive layer unit, wherein all three layer units have in reactive association an independently selected dye-forming coupler and an independently selected blocked developer, wherein the dye couplers are the same in only two of the layer units and wherein the blocked developer is different in said two layer units. Alternatively, the element can comprise a red-light-sensitive layer unit, a green-light-sensitive layer unit and a blue-light-sensitive layer unit, wherein two layer units have in reactive association a common dye-forming coupler, wherein the third layer unit has a distinct coupler, and wherein the blocked developer is the same in two of the layer units.
In a preferred variant, the element is a photothermographic element. In this embodiment, an imagewise exposed element is developed by heat treatment. In another variant of the first embodiment, an imagewise exposed element is developed by treatment with base 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 co
Irving Lyn M.
Szajewski Richard P.
Barts Samuel
Eastman Kodak Company
Konkol Chris P.
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