Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
2001-05-25
2003-04-22
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S566000, C430S955000, C430S959000, C430S351000, C430S380000, C430S542000
Reexamination Certificate
active
06551768
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an imaging element containing a blocked photographically useful compound that decomposes thermally via a Lossen rearrangement reaction.
BACKGROUND OF THE INVENTION
In conventional color photography, films containing light-sensitive silver halide are employed in hand-held cameras. Upon exposure, the film carries a latent image that is only revealed after suitable processing. These elements have historically been processed by treating the camera-exposed film with at least a developing solution having a developing agent that acts to form an image in cooperation with components in the film. Developing agents commonly used are reducing agents, for example, p-aminophenols or p-phenylenediamines.
Typically, developing agents (also herein referred to as developers) present in developer solutions are brought into reactive association with exposed photographic film elements at the time of processing. Segregation of the developer and the film element has been necessary because the incorporation of developers directly into sensitized photographic elements can lead to desensitization of the silver halide emulsion and undesirable fog. Considerable effort, however, has been directed to producing effective blocked developing agents (also referred to herein as blocked developers) that might be introduced into silver halide emulsion elements without deleterious desensitization or fog effects. Accordingly, blocked developing agents have been sought that would unblock under preselected conditions of development after which such developing agents would be free to participate in image-forming (dye or silver metal forming) reactions.
U.S. Pat. No. 3,342,599 to Reeves discloses the use of Schiff-base developer precursors. Schleigh and Faul, in a
Research Disclosure
(129 (1975) pp. 27-30), describe the quaternary blocking of color developers and the acetamido blocking of p-phenylenediamines. (All Research Disclosures referenced herein are published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, Hampshire P010 7DQ, ENGLAND.) Subsequently, 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 blocked p-phenylenediamines in an image-receiving sheet for color diffusion transfer.
All of these approaches 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, lack of simple methods for releasing the blocked developer, inadequate or poor image formation, and other problems. Especially in the area of photothermographic color films, other potential problems include poor discrimination and poor dye-forming activity.
Recent developments in blocking and switching chemistry have led to blocked developing agents, including p-phenylenediamines, that perform relatively well. In particular, compounds having “&bgr;-ketoester” type blocking groups (strictly, &bgr;-ketoacyl blocking groups) are described in U.S. Pat. No. 5,019,492. With the advent of the &bgr;-ketoester blocking chemistry, it has become possible to incorporate p-phenylenediamine developers in film systems in a form from which they only become active when required for development. The &bgr;-ketoacyl blocked developers are released from the film layers in which they are incorporated by an alkaline developing solution containing a dinucleophile, for example hydroxylamine.
Lossen rearrangement is a well documented chemical reaction that is used to produce amines (J. March, “Advanced Organic Chemistry” Fourth Edition, John Wiley & Sons, 1992, New York—Chichester—Brisbane—Toronto —Singapore, p.1093). This approach was used to thermally release carboxylic acids from simple blocked precursors (U.S. Pat. No. 4,610,957 to Kato and Kitaguchi, 1986), and no timing groups were employed.
PROBLEM TO BE SOLVED BY THE INVENTION
There remains a need for blocked photographically useful compounds with good keeping properties, which at the same time exhibit good unblocking kinetics. With respect to developing agents, it is an object to obtain a film incorporating blocked developing agents that provide good dye-forming activity and which, at the same time, yield little or no increased fog and/or provide little or no decrease in Dmax after storage.
SUMMARY OF THE INVENTION
This application describes a new class of blocked photographically useful groups (PUG), decomposing thermally via Lossen rearrangement, that performs better than other classes of blocked PUGS. The invention further relates to a light sensitive photographic element comprising a support and a compound having a blocked compound as described above that releases a photographically useful group on thermal activation.
In one embodiment of the invention, the photographically useful group is a developer in a photothermographic color film. Preferably, when the developer is used in a dry physical development system, the developer is thermally activated at temperatures between about 100 and 160° C. When the developer is used in the presence of some water, in a low volume (even apparently dry) chemical development system, however, the developer is preferably thermally activated at temperatures between about 20 and 100° C. in the presence of added acid, base or water.
The invention additionally relates to a method of image formation having the steps of: thermally developing an imagewise exposed photographic element having a blocked compound as described above that decomposes (i.e., unblocks) on thermal activation to release a photographically useful group to form a developed image. Preferably, following development, the developed image is then scanned to form a fist electronic-image representation (or “electronic record”) from said developed image, the first electronic record is digitized to form a digital image, and the digital image is modified to form a second electronic-image representation, which can be stored, transmitted, printed or displayed.
The invention further relates to a one-time use camera having a light sensitive photographic element comprising a support and a blocked compound as described above that releases a photographically useful group on thermal activation. The invention further relates to a method of image formation having the steps of imagewise exposing such a light sensitive photographic element in a one-time-use camera having a heater and thermally processing the exposed element in the camera.
DETAILED DESCRIPTION OF THE INVENTION
The new class of compounds according to the present invention, having blocked photographically useful groups (PUG) that decompose thermally via Lossen rearrangement, are represented by the following Structure I:
wherein:
PUG is a photographically useful group in which the PUG is connected to the remainder of the molecule by a heteroatom;
LINK1 and LINK2 are linking groups;
TIME is a timing group;
1 is 0 or 1;
m is 0 or 1;
n is 0 or 1;
provided that when m=0 then 1=0;
X is carbon atom, aryl group or heteroaromatic group;
Y is z independently selected substituents, electron donating or electron withdrawing, wherein z is 0 to 7; additionally two substituents Y can join to form a ring. Suitable heteroatoms are oxygen, nitrogen and sulfur. In one embodiment, when n=0, then 1=1, although it is not required in other embodiments. The timing group, if present, is preferably connected to the LINK2 via an oxygen, sulfur, or nitrogen atom, more preferably through an oxygen atom.
In one embodiment, the compounds according to the invention are represented by the following Structure II
wherein the groups are as defined above. In a preferred embodiment, n is 1.
In another embodiment of the invention, the compounds according to the present invention are represented by compounds having the following Structure III:
wherein:
PUG is a photographically useful group;
LINK1 is a linking
Levy David H.
Slusarek Wojciech K.
Yang Xiqiang
Eastman Kodak Company
Konkol Chris P.
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