Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Bleach or intensification
Reexamination Certificate
2001-02-13
2002-12-31
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Bleach or intensification
C430S379000, C430S427000, C430S432000
Reexamination Certificate
active
06500606
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to novel photographic processing compositions. In particular, it relates to novel photographic prebleaching and conditioning compositions that are useful in the processing of color reversal photographic materials. This invention is useful in the photographic industry.
BACKGROUND OF THE INVENTION
The conventional image-forming process of silver halide photography includes imagewise exposure of a photographic silver halide recording material to actinic radiation (such as visible light), and the eventual manifestation of a useable image by wet photochemical processing of that exposed material. A fundamental step of photochemical processing is the treatment of the material with one or more developing agents to reduce silver halide to silver metal. With black-and-white photographic materials, the metallic silver usually comprises the image. With color photographic materials, the useful image consists of one or more organic dye images produced from an oxidized color developing agent formed wherever silver halide is reduced to metallic silver.
To obtain useful color images, it is usually necessary to remove all of the silver from the photographic element after color development. This is sometimes known as “desilvering”. Removal of silver is generally accomplished by oxidizing the metallic silver, and then dissolving it and undeveloped silver halide with a “solvent” or fixing agent in what is known as a fixing step. Oxidation is achieved using an oxidizing agent, commonly known as a bleaching agent. For some processing methods, these two functions can be performed in the same processing step in what is known as bleach-fixing.
Color reversal photographic silver halide materials can be used to provide “positive” color images. One commercially important process intended to provide these positive color images in such materials uses the following sequence of processing steps: first development (using black-and-white silver developer), washing, reversal bath, color development (to provide a dye image), bleaching, fixing, washing, and stabilizing as described in U.S. Pat. No. 4,786,583 (Schwartz). Another useful process has the same steps, but stabilizing is carried out between color development and bleaching.
In such photographic processes, a bleach-accelerator bath is often used between the color development and bleaching steps. The bleach-accelerator bath is also known as a “conditioning” bath or solution. It is used to “condition” the metallic silver developed in the two developing steps, for complete oxidation to silver halide and to help preserve the acidity of the bleaching solution by reducing carryover of color developer into the bleaching solution. Where the “conditioning” solution contains an effective amount of a bleach accelerating agent, the solution is also known as a “prebleaching” solution. The bleach accelerating agent is imbibed into the emulsion layers of the color reversal photographic material during treatment with the prebleaching solution, and is accordingly present to exert its intended effect when the material is put into the bleaching solution.
Thus, the color reversal photochemical processing methods can include the use of a “conditioning” composition, a “prebleaching” composition, or both.
Conventional color reversal processing is also known from U.S. Pat. No. 4,921,779 (Cullinan et al), U.S. Pat. No. 4,975,356 (Cullinan et al), and U.S. Pat. No. 5,037,725 (Cullinan et al) as well as the conventional Process E-6 procedure using color reversal processing chemicals that can be obtained from Eastman Kodak Company (Rochester, N.Y.). Such processes include the use of a prebleaching composition that generally includes a formaldehyde precursor (such as sodium formaldehyde bisulfite, hexamethylenetetramine, or various methylol compounds) and various bleach accelerating agents such as aliphatic thiols including thioglycerol.
Another function of some prebleaching or conditioning compositions is that they may also contain dye stain reducing agents or dye stabilizers to provide image stability when certain spectral sensitizing dyes are retained in processed materials, as described for example in U.S. Pat. No. 6,153,365 (Goswami et al.).
One disadvantage of some aliphatic thiol bleach accelerating agents is that they readily react with oxygen in air and thus the prebleaching compositions have limited storage or shelf stability as well as reduced activity in the processing equipment. Over extended exposure to air in the processing equipment, the compositions lose their “activity” or ability to accelerate bleaching. Another disadvantage of such aliphatic thiols is that they sometimes emit objectionable odors.
There is a need then for prebleaching compositions that are more stable to oxygen but also provide all of the other desired photographic properties in processed color reversal photographic materials.
SUMMARY OF THE INVENTION
The problems with known processing methods and compositions are overcome with a photographic processing composition comprising:
a) at least 0.0001 mol/l of a cyclic mercapto bleach accelerating agent, and
b) at least 0.0001 mol/l of a water-soluble or water-dispersible 2,6-diarylaminotriazine or diaminostilbene dye stain reducing agent,
the amounts of the dye stain reducing agent and bleach accelerating agent being determined according to the following equation:
[bleach accelerating agent, mol/l]≧0.01−10[dye stain reducing agent, mol/l].
This processing composition can also include a formaldehyde precursor.
This invention also provides a concentrated photographic processing composition comprising:
a) at least 0.0002 mol/l of a cyclic mercapto bleach accelerating agent, and
b) at least 0.0002 mol/l of a water-soluble or water-dispersible 2,6-diarylaminotriazine or diaminostilbene dye stain reducing agent,
the amounts of the dye stain reducing agent and bleach accelerating agent being determined according to the equation noted above.
This concentrated processing composition can also include a formaldehyde precursor.
Further, this invention provides a photographic processing kit comprising:
I) one of the photographic processing compositions described above (with or without a formaldehyde precursor), and
II) one or more of a photographic color developing composition, a photographic bleaching composition, a photographic bleach-fixing composition, a photographic fixing composition, a photographic reversal composition, a black-and-white developing composition, or a dye stabilizing and/or final rinse composition.
Still again, a method of the present invention provides a positive color photographic image comprising contacting an imagewise exposed and color developed, color reversal photographic silver halide material with the photographic processing composition described above.
The present invention provides the desired prebleaching and/or conditioning compositions, both in concentrated and working strength forms that have improved storage stability in the presence of oxygen. In other words, the compositions are less sensitive to aerial oxidation. These benefits were unexpectedly found by using a combination of certain spectral sensitizing dye stain reducing agents and cyclic mercapto compounds that act as silver bleach accelerating agents. This combination of compounds in the prebleaching and/or conditioning compositions also has been found to consistently facilitate the reduction of residual silver during bleaching below the desired level of 10.8 mg/m
2
compared to the use of each type of compound alone in the compositions. Thus, each type of compound alone provides insufficient bleach acceleration or “activation” compared to the combination of compounds. Moreover, the use of the cyclic mercapto compounds as bleach accelerating agents avoids the use of aliphatic thiols that may emit objectionable odors.
DETAILED DESCRIPTION OF THE INVENTION
The processing compositions of the present invention generally contain two essential components: a cyclic mercapto bleach accelerating agent and
Goswami Ramanuj
Price Harry J.
Youngblood Michael P.
Eastman Kodak Company
Le Hoa Van
Tucker J. Lanny
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