Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
2001-01-05
2002-08-06
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S955000, C430S598000, C430S599000, C430S600000, C430S603000, C430S607000, C430S611000, C430S613000
Reexamination Certificate
active
06428947
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a multicolor photographic element having improved latent image keeping and to a method of improving the latent image keeping of a multicolor photographic element.
BACKGROUND OF THE INVENTION
Stability of silver halide color photographic materials under various storage conditions is an important characteristic, particularly for materials designed for use in consumer markets, where storage conditions may be quite variable. One aspect of this stability is stability of the latent image formed on exposure of the material. Instability of the latent image leads to undesirable changes in the photographic speed of the material as a function of storage after exposure but before processing in a photographic developer. This instability can be particularly troublesome in multilayer color photographic materials if the latent image keeping density changes are variable in the different color records of the multicolor element. This variability can lead to mismatches in the speed and curve shape of the color records. Various materials have been disclosed in the prior art for stabilizing the latent image including N-alkynyl benzothiazoliums (U.S. Pat. No. 4,780,400), N-(2-benzoxazolyl) propargyl amines (U.S. Pat. Nos. 4378426 and 4,451,557), 2-hydroxyamino-1,3,5-triazines, hydroxyamic acids (U.S. Pat. Nos. 4339515 and 4,330,606) and the like. A number of these materials have the characteristic that they diffuse throughout the multilayer photographic element so that the latent image keeping characteristics of the different color records cannot be separately adjusted. In addition, many of these materials function better in blue sensitized layers than in red or green sensitized layers. Consequently, achieving good stability of the latent image, especially in green or red sensitized layers, continues to be a problem in practical color multilayer photographic materials.
PROBLEM TO BE SOLVED BY THE INVENTION
It is desirable to find new means to control latent image keeping speed and density changes for multicolor photographic elements. It is particularly desirable to find means that allow the latent image keeping speed and density changes to be adjusted separately in the different color records of the multicolor photographic element.
SUMMARY OF THE INVENTION
One aspect of this invention comprises a multicolor photographic element comprising a support bearing a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, wherein at least one of said red-sensitive or green-sensitive layers comprises a fragmentable electron donating compound of the formula: X—Y′ or a compound which contains a moiety of the formula —X—Y′;
wherein the speed gain deriving from addition of said compound to said layer is less than or equal to 0.05 log sensitivity units and wherein
X is an electron donor moiety, Y′ is a leaving proton H or a leaving group Y, with the proviso that if Y′ is a proton, a base, &bgr;
−
, is present in the emulsion layer, and wherein:
1) X—Y′ has an oxidation potential between 0 and about 1.4 V;
2) the oxidized form of X—Y′ undergoes a bond cleavage reaction to give the radical X
·
and the leaving fragment Y′; and
3) the radical X
·
has an oxidation potential ≦−0.7V (that is, equal to or more negative than about −0.7V).
Another aspect of this invention comprises a method of improving the latent image keeping of a multilayer photographic element comprising a support bearing a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, wherein for at least one of said red-sensitive or green-sensitive layers, said method comprises adding a fragmentable electron donating compound of the formula: X—Y′ or a compound which contains a moiety of the formula —X—Y′, in an amount sufficient to improve the latent image keeping but insufficient to impart a speed gain deriving from addition of said compound to said layer of more than 0.05 log sensitivity units and wherein
X is an electron donor moiety, Y′ is a leaving proton H or a leaving group Y, with the proviso that if Y′ is a proton, a base, &bgr;
−
, is present in the emulsion layer, and wherein:
1) X—Y′ has an oxidation potential between 0 and about 1.4 V;
2) the oxidized form of X—Y′ undergoes a bond cleavage reaction to give the radical X
·
and the leaving fragment Y′; and,
3) the radical X
·
has an oxidation potential ≦−0.7V.
ADVANTAGEOUS EFFECT OF THE INVENTION
This invention provides a multicolor photographic element having little speed or density loss with latent image keeping and latent image keeping characteristics that are well matched between the different color records.
DETAILED DESCRIPTION OF THE INVENTION
We have found that addition of a small amount of fragmentable two-electron donor to the emulsion layers of a multilayer color photographic element can significantly improve the latent image stability of the material. Fragmentable two electron donors (FED's) are compounds that have been designed to improve the speed of photographic materials by providing two electrons for each photon absorbed by the silver halide emulsion. Fragmentable electron donating compounds are described in U.S. Pat. Nos. 5,747,235 and 5,747,236 and 5,994,051, 6,010,841, 6,054,260 and 6,153,371, the entire disclosures thereof are incorporated herein by reference. These references disclose speed gains associated with the use of fragmentable two-electron donors in a wide variety of silver halide emulsions. Surprisingly, we have found that, particularly for green and red sensitized emulsions, latent image can be stabilized by use of an amount of fragmentable two-electron donor that gives little or no speed gain when added to the emulsion layer. When the fragmentable two-electron donor is a moiety attached to a silver halide absorptive group or to a sensitizing dye, the additional advantage is obtained that latent image keeping changes can be controlled independently in the different color records of the multicolor element. Independent control of latent image keeping changes in the different layers (fast, mid, or slow) of a given color record is also possible.
One aspect of this invention comprises a multicolor photographic element comprising a support bearing a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler, wherein at least one of said red-sensitive or green-sensitive layers comprises a fragmentable electron donating compound of the formula: X—Y′ or a compound which contains a moiety of the formula —X—Y′;
wherein the speed gain deriving from addition of said compound to said layer is less than or equal to 0.05 log sensitivity units and wherein
X is an electron donor moiety
Johnston Sharon G.
Lenhard Jerome R.
Muenter Annabel A.
Szatynski Steven P.
Eastman Kodak Company
Letscher Geraldine
Rice Edith A.
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