Radiation imagery chemistry: process – composition – or product th – Nonradiation sensitive image processing compositions or... – Developer
Reexamination Certificate
1999-12-30
2001-11-06
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Nonradiation sensitive image processing compositions or...
Developer
C430S415000, C430S448000, C430S566000
Reexamination Certificate
active
06312879
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an imaging element containing a blocked photographically useful compound, in particular a developer.
BACKGROUND OF THE INVENTION
The photographic arts have a longstanding history of attempts to supply customers with convenient and simple ways to take pictures that serve to record their everyday lives. Conventional color photography has attempted to meet this need by supplying light sensitive silver halide containing films suitable for use 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 image.
The well known chromogenic dye-forming films require reducing agents such as p-aminophenols or p-phenylenediamine developers to form dye images. These reducing agents are typically present in developer solutions which are then 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 frequently leads to desensitization of the silver halide emulsion and undesirable fog. Considerable 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 un-block under conditions of development so that developer is 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), described the quaternary blocking of color developer 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, and lack of simple methods of releasing the blocked developer.
Recent developments in blocking and switching chemistry have led to blocked p-phenylenediamines that perform 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.
The incorporation of these blocked developers in photographic elements is typically 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
Thus there is a continuing need for an image-forming element and process that provides consumers with simple and convenient ways to take pictures. In particular, there is a continuing need for imaging elements, particularly photographic and photothermographic imaging elements, that contain a developer in a form that is stable until development yet can rapidly and easily develop the imaging element once processing has been initiated by heating the element and/or by applying a processing solution, such as a solution of a base or acid or pure water, to the element without the necessity of the presence of a dinucleophile. The existence of such a developer chemistry will allow for very rapidly processed films that can be processed simply and efficiently in low cost photoprocessing kiosks.
Similarly, there is a need for incorporating other photographically useful compounds into a photographic element such that they remain stable until processing and are then rapidly released. Such photographically useful compounds include, couplers, dyes and dye precursors, electron transfer agents, etc., as discussed more fully below.
SUMMARY OF THE INVENTION
This invention relates to a carbamate blocked compound whose decomposition, assisted by formation of a carbonium ion, produces a photographically useful group on thermal activation. In a preferred embodiment the photographically useful group is a developer.
In one embodiment, thermal activation preferably occurs at temperatures between about 100 and 160° C. In another embodiment, thermal activation preferably occurs at temperatures between about 20 and 100° C. in the presence of added acid, base or water.
The invention further relates to a light sensitive photographic element comprising a support and having a carbamate blocked compound that decomposes by a carbonium ion assisted elimination mechanism, releasing a photographically useful group on thermal activation.
The invention additionally relates to a method of image formation having the steps of: thermally developing an imagewise exposed photographic element having a carbamate blocked compound that decomposes by a carbonium ion assisted elimination mechanism, releasing a photographically useful group on thermal activation to form a developed image, scanning said developed image to form a first electronic image representation from said developed image, digitizing said first electronic record to form a digital image, modifying said digital image to form a second electronic image representation, and storing, transmitting, printing or displaying said second electronic image representation.
The invention further relates to a one-time use camera having a light sensitive photographic element comprising a support and a compound having a carbamate blocked compound that decomposes by a carbonium ion assisted elimination mechanism, releasing a photographically useful group on thermal activation.
The invention further relates to a method of image formation having the steps of imagewise exposing a light sensitive photographic element comprising a support and a compound having a carbamate blocked compound that decomposes by a carbonium ion assisted elimination mechanism, releasing a photographically useful group on thermal activation in a one-time-use camera having a heater and thermally processing the exposed element in the camera.
In a more preferred embodiment the photographic element contains a compound having a blocked photographically useful group of Structure I:
wherein
PUG is a photographically useful group;
LINK 1 and LINK 2 are linking groups;
TIME is a timing group;
1 is 0 or 1;
m is 0, 1, or 2;
n is 0 or 1;
A, B, and C are independently hydrogen, or a substituted or unsubstituted alkyl, cyclopropyl, aryl, arylalkyl, or heterocyclic group, or any two of A, B, and C can combine to form a ring, with the proviso that if each of A, B, and C is other than a cyclopropyl, aryl or heterocyclic group, each of A, B, and C is alkyl or arylalkyl.
Preferred s
Irving Lyn M.
Irving Mark E.
Levy David H.
Reynolds James H.
Slusarek Wojciech K.
Eastman Kodak Company
Konkol Chris P.
Le Hoa Van
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