Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
2002-04-12
2003-02-18
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S543000, C430S558000, C430S384000, C430S385000
Reexamination Certificate
active
06521397
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a silver halide photographic element containing an azole coupler having a certain formula that forms a dye having an improved absorption maximum and color gamut.
BACKGROUND OF THE INVENTION
In the photographic art, color images are formed by exposure of a silver halide light sensitive element containing organic dye-forming couplers followed by processing in aqueous developer solutions containing an aromatic primary amine color-developing agent. The resultant dyes formed are yellow, magenta and cyan and result in the formation of a color image in the photographic element.
Although described in the open literature as well as patent literature, 2-benzoxazoleacetonitrile derivatives have never been used as couplers for the generation of azamethine dyes in color paper products. In their most common photographic use, they are reacted with aldehydes to generate methine dyes of general formula 2 that were used for density correction and antihalation as describe in the patent GB 96-22424 by P. Merkel et al.
In another application, 2-benzoxazoleacetonitriles are incorporated into a yellow coupler molecule 3 in a color negative film. Upon coupling with the oxidized developer during the photographic processing, the 2-benzoxazoleacetonitrile fragment is released as a yellow methine dye of an absorbance maximum similar to the coupler generated azamethine dye, leading to a higher yield of yellow dye as described by J. B. Mooberry et al. in the patent EP 1016916.
Another application involving 2-benzoxazoleacetonitrile derivatives is their use in coupling reactions with hydrazine derivatives to form azodyes during heat-development as reported by O. Uchida in JP 2000321736.
To our knowledge, there is no record of the 2-benzoxazoleacetonitrile described in this invention being used as azamethine dye-forming couplers by reaction with a color developer in a Color Paper.
In the patent applications number U.S. Pat. No. 6,159,674 and U.S. Pat. No. 6,180,328 B1, James L. Edwards described the invention of an improved photographic element for color imaging in which four or five separately sensitized light-sensitive silver halide emulsions are used. In addition to the three conventional cyan, magenta and yellow dye forming layers, a fourth dye-forming layer comprising a coupler capable of generating a “red” dye that has a hue angle in the range of 355° and 75° and a fifth dye-forming layer comprising a coupler capable of generating a “blue” dye that has a hue angle in the range of 225 and 310°, which increased the gamut of colors possible.
Color gamut is an important feature of color printing and imaging systems. It is a measure of the range of colors that can be produced using a given combination of colorants. It is desirable for the color gamut to be as large as possible. The color gamut of the imaging system is controlled primarily by the absorption characteristics of the set of colorants used to produce the image. Silver halide imaging systems typically employ three colorants, including cyan, magenta, and yellow dyes in the conventional subtractive imaging system
The ability to produce an image containing any particular color is limited by the color gamut of the system and materials used to produce the image. Thus, the range of colors available for image reproduction is limited by the color gamut that the system and materials can produce.
Color gamut is often thought to be maximized by the use of so-called “block dyes”. In
The Reproduction of Colour
4th ed., R. W. G. Hunt, pp 135-144, it has been suggested that the optimum gamut could be obtained with a subtractive three-color system using three theoretical block dyes where the blocks are separated at approximately 490 nm and 580 nm. This proposal is interesting but cannot be implemented for various reasons. In particular, there are no real organic based couplers that produce dyes corresponding to the proposed block dyes.
Variations in the block dye concept are advanced by Clarkson, M., E., and Vickerstaff, T., in “Brightness and Hue of Present-Day Dyes in Relation to Colour Photography,” Photo. J. 88b, 26 (1948). Three example spectral shapes are given by Clarkson and Vickerstaff: Block, Trapezoidal, and Triangular. The authors conclude, contrary to the teachings of Hunt, that trapezoidal absorption spectra may be preferred to a vertical sided block dye. Again, dyes having these trapezoidal spectra shapes are theoretical and are not available in practice.
Both commercially available dyes and theoretical dyes were investigated in “The Color Gamut Obtainable by the Combination of Subtractive Color Dyes. Optimum Absorption Bands as Defined by Nonlinear Optimization Technique,” J. Imaging Science, 30, 9-12. The author, N. Ohta, deals with the subject of real colorants and notes that the existing curve for a typical cyan dye, as shown in the publication, is the optimum absorption curve for cyan dyes from a gamut standpoint.
McInerney, et al, in U.S. Pat. Nos. 5,679,139; 5,679,140; 5,679,141; and 5,679,142 teach the shape of preferred subtractive dye absorption shapes for use in four color, C,M,Y,K based ink-jet prints.
McInerney, et al, in EP 0825,488 teach the shape of preferred subtractive cyan dye absorption shape for use in silver halide based color prints.
Kitchin, et al, in U.S. Pat. No. 4,705,745, teach the preparation of a photographic element for preparing half-tone color proofs comprising four separate imaging layers capable of producing cyan, magenta, yellow and black images.
Powers, et al, in U.S. Pat. No. 4,816,378, teach an imaging process for the preparation of color half-tone images that contain cyan, magenta, yellow and, black images. The use of the black dye does little to improve the gamut of color reproduction.
Haraga, et al, in EP 0915374A1, teach a method for improving image clarity by mixing ‘invisible’ information in the original scene with a color print and reproducing it as an infrared dye, magenta dye or as a mixture of cyan magenta and yellow dyes to achieve improved color tone and realism. The addition of the resulting infrared, magenta or black dye does little to improve the gamut.
In spite of the foregoing teachings relative to color gamut, the coupler sets which have been employed in silver halide color imaging have not provided the range of gamut desired for modern digital imaging; especially for so-called ‘spot colors’, Pantone® colors, or ‘HiFi colors’.
In the patent U.S. Pat. No. 6,159,674, James Edwards also recommends the use of cyanoacetanilides as couplers in a fourth sensitized photographic layer to produce the increase in Color Gamut. The couplers useful in this invention produce a superior dye density as well as a higher speed compared to 2-cyanoacetanilides described by this prior patent. On top of that, embodiments of the invention also produce a paper with a color gamut that is equal or superior to a paper containing the cyanoacetanilide couplers reported by the patent.
It is a problem to be solved to provide an improved coupler set that provides an improved color density in the spectral region of 490 to 520 nm as well as an increase in color gamut to improve the accuracy of color reproduction.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a photographic element comprising a support bearing a light sensitive silver halide emulsion layer having associated therewith a dye forming coupler having formula I,
wherein:
Ballast is a group containing at least 6 aliphatic carbon atoms,
V represents a chain of three or four atoms, which may be substituted, selected from C, N, O and S sufficient to form an aromatic ring fused to the azole ring and n is 0 or 1, provided that if n is 0, Y and Ballast are directly attached to the 5-membered azole ring;
W is an electron withdrawing group selected from the group consisting of —CN, —CONR
1
R
2
, —CO
2
R
1
, —NO
2
, and —SO
2
R
1
where R
1
and R
2
are H or substituents,
X is H or a coupling-off group;
Y is H or a substituent;
Z is an atom or group selected from >N—R, —O—, and —S
Diehl Donald R.
Edwards James L.
Kapiamba Mbiya
Lincoln David G.
Russo Gary M.
Eastman Kodak Company
Kluegel Arthur E.
Letscher Geraldine
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