Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Developer
Reexamination Certificate
2002-02-15
2003-07-29
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Developer
Reexamination Certificate
active
06599688
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to concentrated and working strength photographic color developing compositions that have improved stability, and to methods for their use. This invention is useful in the field of photography to provide color photographic images.
BACKGROUND OF THE INVENTION
The basic processes for obtaining useful color images from exposed color photographic silver halide materials include several steps of photochemical processing such as color development, silver bleaching, silver halide fixing and water washing or dye image stabilizing using appropriate photochemical compositions.
Photographic color developing compositions are used to process color photographic materials such as color photographic films and papers to provide the desired dye images early in the photoprocessing method. Such compositions generally contain color developing agents, for example 4-amino-3-methyl-N-(2-methane sulfonamidoethyl)aniline, as reducing agents to react with suitable color forming couplers to form the desired dyes. U.S. Pat. No. 4,892,804 (Vincent et al.) describes conventional color developing compositions that have found considerable commercial success in the photographic industry. Other known color developing compositions are described in U.S. Pat. No. 4,876,174 (Ishikawa et al.), U.S. Pat. No. 5,354,646 (Kobayashi et al.), and U.S. Pat. No. 5,660,974 (Marrese et al.).
It is generally known that the concentrations of various photochemicals used in a photographic color developing composition must be within certain narrow limits in order to provide optimal performance. This is particularly true of “concentrates” or single-part compositions.
There is a trend in the photographic industry to provide photoprocessing compositions (including color developing compositions) in concentrated form so that the manufacturer and user need not pay for use, transport or storage of large volumes of water, and to enable use of smaller containers. Moreover, there has been a desire in the industry to provide compositions that can be used right out of their containers without the need for mixing various components (thereby reducing mixing errors), such as in what are known as “automatic replenishing” processors.
One concentrated form known in the art is a chemical paste or slurry, as described for example in EP-A-0 204,372 (Chemco) and EP-A-0 800,111 (Fuji Photo). These formulations have still other disadvantages, namely lack of homogeneity and slow dissolution rate of solid components.
Additional small volume, ready to use color developing compositions are described in U.S. Pat. No. 5,273,865 (Loiacono et al.). These compositions are said to be free of bromides, hydroxylamines and benzyl alcohol, to include a polyol compound having 4 to 8 hydroxy groups, and to be useful for rapid access processing of photographic elements having high silver bromide emulsions only.
A very useful single-part color developing composition that is homogeneous, concentrated, and stable is described and claimed in U.S. Pat. No. 6,077,651 (Darmon et al.). Such compositions are stable from the presence of the free base form of the color developing agent and a particular amount of water-soluble organic solvent.
Stability of the color developing agents in such compositions is generally achieved using sulfite ions or any of the many conventional organic antioxidants (or preservatives) that reduce aerial oxidation rates. For example, U.S. Pat. Nos. 4,892,804, 4,876,174, 5,354,646, and 5,660,974 (all noted above) describe hundreds of possible derivatives of hydroxylamines that can be used as antioxidants in color developing compositions.
However, there is a desire in the photoprocessing industry to find additional means of stabilizing color developing compositions, especially concentrated compositions. There is also a desire to reduce the amounts of organic antioxidants for a number of reasons without losing the ability to reduce aerial oxidation.
SUMMARY OF THE INVENTION
This invention addresses the problems noted above with a concentrated aqueous photographic color developing composition having a pH of from about 7 to about 13 and comprising:
a) at least 0.005 mol/l of a color developing agent,
b) at least 0.005 mol/l of an antioxidant for the color developing agent, and
c) from about 0.01 to about 2.5 mol/l of an &agr;-ketocarboxylic acid or salt thereof as a stabilizing agent.
This invention also provides a concentrated, aqueous, single-part color developing composition having a pH of from about 8 to about 12 and comprising:
a) from about 0.005 to about 1 mol/l of a color developing agent in free base form,
b) from about 0.005 to about 1 mol/l of a hydroxylamine derivative antioxidant for the color developing agent,
c) a water-miscible or water-soluble hydroxy-substituted, straight-chain organic solvent that has a molecular weight of from about 50 to about 200,
d) a buffering agent that is soluble in the organic solvent,
e) from about 0.005 to about 0.3 mol/l of a calcium ion sequestering agent, and
f) at least 0.01 mol/l of an &agr;-ketocarboxylic acid, or a salt thereof, as a stabilizing agent.
An aqueous working strength color developing composition of this invention has a pH of from about 7 to about 13 and comprises:
a) at least 0.0005 mol/l of a color developing agent,
b) at least 0.0005 mol/l of an antioxidant for the color developing agent, and
c) from about 0.005 to about 0.25 mol/l of an &agr;-ketocarboxylic acid or salt thereof as a stabilizing agent.
An aqueous working strength color developing composition can also be prepared by diluting the concentrated aqueous color developing composition described above at least two times.
Further, a method for providing a color image in a color photographic silver halide element comprises contacting the element with the concentrated aqueous photographic color developing composition described above.
Alternatively, a method for providing a color image in a color photographic silver halide element comprises contacting the element with an aqueous working strength color developing composition that is prepared by diluting the concentrated aqueous color developing composition described above at least two times.
Still further, a method of photographic processing comprises the steps of:
A) color developing an imagewise exposed color photographic silver halide element with a photographic color developing composition comprising an &agr;-ketocarboxylic acid or salt thereof, and
B) desilvering the color developed color photographic silver halide element.
The color developing step in a photographic processing method can be followed by desilvering the color developed color photographic silver halide element, as well as any other useful photoprocessing steps known in the art.
The color developing composition of this invention offers a number of advantages over the color developing compositions currently available or known in the art. The concentrated and working strength compositions of this invention are stabilized with the presence of an &agr;-ketocarboxylic acid or a salt thereof. This means that the chemical loss (breakdown) of color developing agent is reduced. Moreover, the amount of conventional organic antioxidants, such as hydroxylamine derivatives, can be reduced without sacrificing composition stability. This may allow for reduced odors or component costs by using less hydroxylamine derivatives in the compositions.
DETAILED DESCRIPTION OF THE INVENTION
In one embodiment, the color developing composition of this invention can be formulated as an aqueous concentrate, such as a single-part concentrate, that can then be diluted at least two times with water or buffer (preferably at least four times) to form a working strength color developing composition. Alternatively, the working strength composition of this invention can be prepared by mixing all of the desired components in any desired order at working strength concentrations.
The compositions of this invention contain one or more color developing agents that may be in the form of a sulfate salt or in f
Haye Shirleyanne E.
Huston Janet M.
Eastman Kodak Company
Le Hoa Van
Tucker J. Lanny
LandOfFree
Stable photographic color developing composition and method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Stable photographic color developing composition and method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Stable photographic color developing composition and method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3036612