Radiation imagery chemistry: process – composition – or product th – Post imaging processing – Using web or gel
Reexamination Certificate
2000-06-13
2001-11-13
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Post imaging processing
Using web or gel
Reexamination Certificate
active
06316173
ABSTRACT:
FIELD OF THE INVENTION
This invention pertains to a sheet comprising a reducing agent ionically bound to an ion exchange matrix and to methods of processing photographic elements in the presence of said sheet.
BACKGROUND OF THE INVENTION
It is well known in the art that the introduction of photographically useful compounds, such as photographic developers, couplers, development inhibitors, electron transfer agents, base precursors, fixing agents, i.e., ligand capable of binding silver, silver stabilizing agents and the like, into photographic elements can lead to premature reaction of the photographically useful compound with the other components of the photographic element. For example, placing conventional color developers, such as p-phenylenediamines and p-aminophenols, into sensitized photographic elements leads to desensitization of the silver halide emulsion and unsuitable fog. Much effort has therefore been directed at trying to produce effective blocked developers, which can be introduced in silver halide emulsion elements without deleterious desensitization or fog effects and which unblock chemically under conditions of development so that developer is free to participate in color forming (dye forming) reactions.
U.S. Pat. No. 3,342,599, to Reeves, discloses the use of Schiff base developer precursors. U.S. Pat. No. 4,157,915, to Hamaoka et al., and U.S. Pat. No. 4,060,418, to Waxman and Mourning, describe the preparation and use of carbamate blocked p-phenylenediamines. Color developing agents having &agr;-ketoacyl blocking groups are described in U.S. Pat. No 5,019,492.
All of these approaches and inventions have failed in practical product applications because of one or more of the following problems: desensitization of sensitized silver halide; unacceptably slow unblocking kinetics; instability of blocked developer yielding increased fog and/or decreased Dmax after storage; and the requirement of a dinucleophile, such as hydroxylamine, to initiate developer release.
The addition of a blocking group to a color developing agent results in an increase in molecular weight and generally results in a decrease in water solubility of the resulting blocked version of the parent color developing agent. As a result, the incorporation of these blocked developers in photographic elements is carried out using colloidal gelatin dispersions of the blocked developers. These dispersions are prepared using means well known in the art, wherein the developer precursor is dissolved in a high vapor pressure organic solvent (for example, ethyl acetate), along with, in some cases, a low vapor pressure organic solvent (such as dibutylphthalate), and then emulsified with an aqueous surfactant and gelatin solution. After emulsification, usually done with a colloid mill, the high vapor pressure organic solvent is removed by evaporation or by washing, as is well known in the art.
PROBLEM TO BE SOLVED BY THE INVENTION
There has been a need for a photographic element incorporating a photographically useful compound, such as a developing agent, which is stable until development. Then, the element can be developed rapidly and easily. There has also been a need to simplify the preparation of the developer dispersion method and to eliminate the need for organic solvents in coating formulations. There has also be en a need for a process for developing an image in a photographic element which employs a developing solution having a simplified composition.
SUMMARY OF THE INVENTION
These an d other needs have been satisfied by providing a photographically useful reducing agent, such as a developer, in a sheet that can be brought into reactive association with an photographic element after said element has been imagewise exposed to light.
One aspect of this invention comprises a sheet comprising at least one photographically useful reducing agent ionically bound to an ion exchange matrix. In preferred embodiments of the invention, the sheet further comprises a binder and/or support and the ion exchange matrix comprises particles having an average particle size of less than about 10 micrometers (&mgr;m).
The sheet can be prepared by any suitable process, for example the sheet can be formed of a solution of the ion exchange matrix in a solvent. In preferred embodiments of the invention, the ion exchange matrix is in the form of particles. To form the sheet a binder is added to the solution before casting. Suitable binders include, for example, cellulose derivatives (e.g., cellulose esters), gelatin (e.g., alkali-treated gelatin such as cattle bone or hide gelatin, or acid treated gelatin such as pigskin gelatin), deionized gelatin, gelatin derivatives (e.g., acetylated gelatin, phthalated gelatin, and the like) synthetic polymers, carriers, such as poly(vinyl alcohol), poly(vinyl lactams), acrylamide polymers, polyvinyl acetals, polymers of alkyl and sulfoalkyl acrylates and methacrylates, hydrolyzed polyvinyl acetates, polyamides, polyvinyl pyridine, methacrylamide copolymers, and the like. The amount of binder used is from about 1:3 to about 10: 1, based on the weight of the ion exchange matrix.
In preferred embodiment of the invention, a layer of binder plus ion exchange matrix is coated onto a support. Suitable supports include, for example, polymeric film, wood fiber, e.g., paper, metallic sheet and foil, glass and ceramic supporting elements. Preferred supports include, for example, polymeric film supports including films of cellulose nitrate and cellulose esters (such as cellulose triacetate and diacetate), polystyrene, polyamides, homo- and copolymers of vinyl chloride, poly(vinyl acetal), polycarbonate, homo- and copolymers of olefins such as polyethylene and polypropylene, and polyesters of dibasic aromatic carboxylic acids with divalent alcohols such as poly(ethylene terephthalate) or poly(ethylene naphthalate).
Another aspect of this invention comprises a method of processing a photographic element comprising at least one silver halide light-sensitive emulsion layer which comprises contacting the element with (a) a processing solution and (b) a sheet comprising a photographically useful reducing agent ionically bound to ion exchange matrix.
A further aspect if this invention comprises a method of processing a photographic element comprising at least one silver halide light-sensitive emulsion layer which comprises contacting the element with (a) a processing solution having a pH of about 8-13 and (b) a sheet comprising a photographically useful reducing agent ionically bound to an ionic exchange matrix.
A further aspect of this invention comprises a method of processing a photographic element comprising at least one silver halide light-sensitive emulsion layer which comprises contacting the element with (a) a processing solution having an ionic strength of greater than 0.001 M and (b) a sheet comprising a photographically useful reducing agent ionically bound to an ion exchange matrix.
Still another aspect of this invention comprises a method of processing a photographic element comprising at least one silver halide light-sensitive layer which comprises contacting the element with (a) a sheet comprising a photographically useful reducing agent ionically bound to an ion exchange matrix and (b) with thermal energy to elevate the temperature above 50° C.
Still a further aspect of this invention comprises a method of imaging comprising the steps of:
forming an image in an imagewise exposed light-sensitive silver halide element by one of the methods described above;
scanning said formed image to form a first electronic image representation from said formed image;
digitizing said first electronic image to form a digital image;
modifying said digital image to form a second electronic image representation; and
transforming, storing, transmitting, printing or displaying said second electronic image representation.
Yet a further aspect of this invention comprises a method of forming an image comprising the steps of:
forming an image in an imagewise exposed light-sensitive silver halide element by one of t
Irving Lyn M.
Irving Mark E.
Noonan John M.
Eastman Kodak Company
Le Hoa Van
Rice Edith A.
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