Radiation imagery chemistry: process – composition – or product th – Color imaging process – Using identified radiation sensitive composition in the...
Reexamination Certificate
2001-08-21
2003-04-15
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Color imaging process
Using identified radiation sensitive composition in the...
C430S383000, C430S385000, C430S543000, C430S546000, C430S551000, C430S552000, C430S553000, C430S512000, C430S931000
Reexamination Certificate
active
06548234
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a colour photographic element containing one or more cyan dye-forming couplers, in particular one or more phenolic cyan couplers, a UV absorber, and a specific class of stabilizer and solvent.
BACKGROUND OF THE INVENTION
In silver halide based colour photography, a typical photographic element contains multiple layers of light-sensitive photographic silver halide emulsions coated on a support with one or more of these layers being spectrally sensitized to each of blue light, green light and red light. The blue, green and red light-sensitive layers typically contain yellow, magenta, and cyan dye-forming couplers, respectively. After exposure to light, colour development is accomplished by immersing the exposed material in an aqueous alkali solution containing an aromatic primary amine colour developing agent. The dye-forming couplers are selected so as to react with the oxidized colour developing agent to provide yellow, magenta and cyan dyes in the so called subtractive colour process to reproduce their complementary colours, blue, green and red as in the original image.
The important features for selecting the dye-forming coupler include; efficient reaction with oxidized colour developing agent, thus minimizing the necessary amounts of coupler and silver halide in the photographic element; the formation of dyes with hues appropriate for the photographic use of interest: for colour photographic paper applications this requires that dyes have low unwanted side absorption leading to good colour reproduction in the photographic print; minimization of image dye loss contributing to improved image permanence under both ambient illumination and conventional storage conditions; and in addition the selected dye-forming coupler must exhibit good solubility in coupler solvents, provide good dispersibility in gelatin and remain stable during handling and manipulation for maximum efficiency in manufacturing processes. The hue of a dye is a function of both the shape and the position of its spectral absorption band. Traditionally, the cyan dyes used in colour photographic papers have had nearly symmetrical absorption bands centred in the region of 620 to 680 nm.
It is well known that the spectral characteristics of the image dyes from couplers can be manipulated by incorporating different function groups into the molecular structure of the coupler, and that the environment in which the dye is situated can also influence the hue of the dye. The choice of permanent solvent is very important not only because of its effect on the final properties of the dye, but also because of its effect on the efficiency of dye formation. The choice of permanent solvent also determines whether an auxiliary solvent is necessary to aid dissolution of coupler. There is a need to avoid the use of auxiliary solvent during the preparation of the coupler dispersion, because the auxiliary solvent needs to be removed, either by washing or evaporation, before dispersion preparation is completed. It takes a long time to remove the auxiliary solvent and this is costly in time and equipment. In addition, with ever-increasing environmental concerns, reducing the amount of auxiliary organic solvent used in dispersions has been of paramount importance. Naturally, without auxiliary solvent, the temperature at which coupler dissolves can be excessively high so any material which can reduce the solubility temperature, would be advantageous.
In recent years, a great deal of study has been conducted to improve dye-forming couplers for silver halide photosensitive materials in terms of improved colour reproducibility and image dye stability. However, further improvements are needed, particularly in the area of cyan couplers. In general, cyan dyes are formed from naphthols and phenols as described, for example, in U.S. Pat. Nos. 2,367,351, 2,423,730, 2,474,293, 2,772,161, 2,772,162, 2,895,826, 2,920,961, 3,002,836, 3,466,622, 3,476,563, 3,552,962, 3,758,308, 3,779,763, 3,839,044, 3,880,661, 3,998,642, 4,333,999, 4,990,436, 4,960,685, 5,476,757 and 5,614,357; in French Patent Nos. 1,478,188 and 1,479,043 and in UK Patent No. 2,070,000.
These types of couplers can be used either by being incorporated in the photographic silver halide emulsion layers or externally in the processing baths. In the former case the couplers must have ballast substituents built into the molecule to prevent the couplers from migrating from one layer into another. Although these couplers have been used extensively in colour photographic film and paper products, the dyes derived from them still suffer from poor stability to heat, humidity or light, low coupling efficiency or optical density, and from undesirable blue and green absorptions which cause considerable reduction in colour reproduction and colour saturation.
Cyan couplers which have been recently proposed to overcome some of these problems are 2,5-diacylaminophenols containing a sulfone, sulfonamido or sulfate moiety in the ballasts at the 5-position, as disclosed in U.S. Pat. Nos. 4,609,619, 4,775,616, 4,849,328, 5,008,180, 5,045,442, and 5,183,729; and Japanese patent applications JP02035450 A2, JP01253742 A2, JP04163448 A2, JP04212152 A2 and JP05204110 A2. Cyan image dyes formed from these couplers show improved stability to heat and humidity, enhanced optical density and resistance to reduction by ferrous ions in the bleach bath.
The 2,5-diacylaminophenol couplers in U.S. Pat. Nos. 5,047,314, 5,047,315, 5,057,408, 5,162,197 and 5,726,003 are of the type which yield dyes with symmetrical absorption bands and high side-band absorptions. The use of certain ester coupler solvents is described in both U.S. Pat. Nos. 5,047,315 and 5,057,408, where examples show these solvents with 2,5-diacylaminophenols. The couplers in these patents are typically embodied in formats with benzotriazole UV absorbers which can provide improved dye stability to light. However these patents do not provide teaching suitable for understanding how these couplers or stabilizers, and especially the couplers of U.S. Pat. No. 5,686,235, affect dye formation efficiency.
Combinations of two classes of phenolic cyan dye-forming couplers are disclosed in U.S. Pat. Nos. 4,537,857, 4,552,836, 4,614,710, 4,666,826, 5,084,375, 4,820,614 and in JP 02 178,259 and JP 02 237,449.
EP-A- 1 037 103 describes a blend of cyan dye-forming couplers together with a benzotriazole stabilizer and optionally an aliphatic ester solvent which provides improved light and dark stability in a photographic element without degradation in hue or reactivity of the dyes therein.
U.S. Pat. Nos. 5,017,465 and 5,082,766 and German published patent application DTOS 4,307,194 describe the use of certain stabilizers with pyrazoloazole magenta dye forming couplers to improve their dye stability. One class of stabilizers which is disclosed includes compounds of the following structure:
wherein A represents the group of non-metal atoms necessary to complete a 5- to 8-remembered nitrogen-containing ring and R
0
represents an aryl group or a heterocyclic group. Preferred compounds of such formula, as described in U.S. Pat. No. 5,017,465, include compounds wherein A represent the atoms necessary to complete a thiomorpholine 1,1-dioxide group and where R
0
represents an alkoxy-substituted phenol group. Such compounds are believed to stabilise by acting as singlet oxygen quenchers. The utility of thiomorpholine dioxide stabilizers in relation to 2-equivalent pyrazolones magenta couplers is also disclosed in U.S. Pat. No.5,491,054 & U.S. Pat. No. 5,484,696. In U.S. Pat. No. 5,561,037 it is disclosed that the light stability of image dyes from cyclic azole magenta couplers can be improved by the use of a combination of stabilizers which include thiomorpholine dioxide compounds as well as substituted sulfonamido phenyl compounds.
U.S. Pat. No. 4,820,614 discloses a blend of cyan couplers with a nitrogen stabilizer combined with a hindered phenol or highly branched piperidine to improve dye stability. According to this
Kluegel Arthur E.
Letscher Geraldine
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