Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Identified radiation sensitive composition with color...
Reexamination Certificate
2002-12-17
2003-10-28
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Identified radiation sensitive composition with color...
C430S503000, C430S502000, C430S543000
Reexamination Certificate
active
06638701
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a silver halide color photographic element containing a red dye-forming coupler wherein the coupler is a pyrazolotriazole having a certain carbonamido containing substituent that provides a red dye having improved dye light stability.
BACKGROUND OF THE INVENTION
In conventional silver halide color imaging, the film employed contains three color records. A yellow dye-forming blue record, a magenta dye forming green record, and a cyan dye forming red record provide the desired color information. The problem with the conventional films is that the gamut of colors that can be formed is not as broad as would be desired and is limited by the combinations that can be made with the combination of the three dyes available.
In U.S. Pat. Nos. 6,159,674 and 6,180,328, Edwards described 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, he proposed an additional 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/or an additional 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 resulted in an increased 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 teaches 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 U.S. Pat. No. 6,159,674, Jim Edwards recommends the use of cyanoacetanilides as couplers in a fourth sensitized photographic layer to produce the increase in Color Gamut. In application Ser. No. 10/122,284, filed Apr. 12, 2002, we demonstrated that 2-benzoxazoleacetonitrile-type couplers showed increased reactivity compared to the cyanoacetanilide couplers. These prior couplers are not entirely satisfactory form the standpoint of dye stability.
It remains a problem to be solved to provide a still further improved red coupler that completes a coupler set that provides an increase in color gamut to improve the accuracy of color reproduction wherein the red dye has an improved stability to light degradation.
SUMMARY OF THE INVENTION
The invention provides a photographic element comprising a light sensitive silver halide emulsion layer having associated therewith a pyrazolotriazole dye forming coupler having formula I
in which
is
and L
1
is linked to the C atom;
L
1
is linked to the triazole ring by a carbon atom substituted by one or two alkyl or aryl groups;
L
2
is a chain of one or two carbon atoms that contains a sulfonyl substituent and that may be further substituted by alkyl or aryl groups;
R1 is selected from the group consisting of alkyl groups containing 1-3 carbon atoms;
R2 is selected from the group consisting of hydrogen, alkyl and aryl groups;
R3 is a substituted carbonyl, carbamoyl, sulfonyl, or sulfamoyl group; and
X is H or a coupling-off group.
DETAILED DESCRIPTION OF THE INVENTION
As summarized above, this patent application relates to the invention of 1H-Pyrazolo-1,2,4-triazoles with a particular substitution pattern that allows a hue shift such that these couplers can be used as “red” couplers in photographic applications. The couplers of this invention generate azamethine dyes that have an absorbance maximum of not more than 530 nm. These dyes are much more stable to light then the azamethine dyes generated from 2-cyanoactanilide or 2-benzoxazoleacetonitrile couplers.
As more fully described hereinafter, the couplers may be used as couplers in a fourth sensitized silver imaging layer in photographic applications. They may be prepared using a 3-substituted 4-amino-3H-1,2,4-Triazole-3-thione in which the 3 substituent is &agr;-p-nitrophenoxyalkyl or &agr;-acetoxyalkyl. These compounds were then converted to the corresponding 6-alkyl or 6-aryl-1H-Pyrazolo 1,2,4-triazole derivatives bearing an &agr;-p-nitrophenoxyalkyl or &agr;-acetoxyalkyl substituent in the 3-position. Substitution of the nitrophenoxy or acetoxy substituent by benzylamine allows the introduction of an amine functionality that can then be converted to the invention couplers by hydrogenolysis and acylation of the resulting free amine.
The photographic element of the invention comprises a light
Bryant Gregg P.
Edwards James L.
Kapiamba Mbiya
Lincoln David G.
Russo Gary M.
Kluegel Arthur E.
Letscher Geraldine
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