Radiation imagery chemistry: process – composition – or product th – Thermographic process – Heat applied after imaging
Reexamination Certificate
2002-03-19
2004-02-03
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Thermographic process
Heat applied after imaging
C430S617000, C430S619000, C430S620000
Reexamination Certificate
active
06686133
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to photothermographic recording materials and recording processes therefor.
BACKGROUND OF THE INVENTION
Thermal imaging or thermography is a recording process wherein images are generated by the use of image-wise modulated thermal energy.
In thermography three approaches are known:
1. Image-wise transfer of an ingredient necessary for the chemical or physical process bringing about changes in colour or optical density to a receptor element containing other of the ingredients necessary for the chemical or physical process followed by uniform heating to bring about the changes in colour or optical density.
2. Thermal dye transfer printing wherein a visible image pattern is formed by transfer of a coloured species from an image-wise heated donor element onto a receptor element.
3. Direct thermal formation of a visible image pattern by image-wise heating of a recording material containing matter that by chemical or physical process changes colour or optical density.
Thermographic materials of type 3 can be rendered photothermographic by incorporating a photosensitive agent which after exposure to UV, visible or IR light is capable of catalyzing or participating in a thermographic process bringing about changes in colour or optical density.
Research Disclosure number 17029, published in June 1978, gives a survey of different methods of preparing organic silver salts in section II. The invention examples of U.S. Pat. No. 5,380,635 and U.S. Pat. No. 5,434,043 describe the production of organic silver salts using fatty acids of the type HUMKO Type 9718 & Type 9022 from WITCO Co., which contain according to the manufacturer's catalogue a mixture of different fatty acids, in connection with their use in photothermographic recording materials. DE-OS 27 21 828 discloses a thermally developable light-sensitive material, consisting of a support, which contains thereon or in one or more layers at least (a) an organic silver salt, (b) a photocatalyst and (c) a reducing agent, wherein the organic silver salt (a) contains at least a silver salt with an uneven number of 21 or more carbon atoms; and examples with mixtures of two and three organic silver salts of monocarboxylic acids precipitated together, but all with 20 or more carbon atoms.
U.S. Pat. No. 5,459,028 discloses a heat-developable photographic recording material comprising: (a) at least one binder layer coated on a support, said binder layer comprising at least one light-sensitive silver halide and a light-insensitive silver salt of a fatty acid; (b) at least one reducing agent; and (c) at least one auxiliary layer containing a developed image stabilizer selected from the group consisting of hexamethylene tetramine and salts thereof, triazaadamantane and salts thereof and compounds derived from hexamethylene tetramine wherein the compounds are derived from hexamethylene tetramine by exchanging one —CH
2
— group with —S—, —SO—, or —SO
2
—; (d) wherein said reducing agent and said developed image stabilizers are in a reactive relationship with the light-insensitive silver salt.
U.S. Pat. No. 5,677,121 discloses a heat-developable silver halide infrared ray-sensitive material comprising a support having on one side of the support an emulsion layer containing a binder, a nonsensitive silver salt, a reducing agent for silver ion and silver halide grains spectrally sensitized at a wavelength within the region of from 750 to 1400 nm, wherein the nonsensitive silver salt comprises a mixture of silver salts of at least three organic carboxylic acids, one of the acids is behenic acid, and the content of the behenic acid in the acids is from not less than 35 to less than 90 mol %.
Recent experiments with substantially light-insensitive thermographic materials incorporating glutaric acid in the thermosensitive element have shown that, unlike substantially light-insensitive thermographic materials incorporating adipic acid or pimelic acid, silver glutarate could not be detected by X-ray diffraction spectroscopy during the thermal development process. Therefore there can be no question of incidental silver glutarate formation upon thermal development of substantially light-insensitive thermographic materials incorporating glutaric acid.
Photothermographic recording materials are required which are thermally processable at lower temperatures to enable a higher throughput to be realized and which are capable of providing images with a higher gradation.
ASPECTS OF THE INVENTION
It is therefore an aspect of the present invention to provide a photothermographic recording material with improved thermal developability without significant deterioration in other photothermographic properties.
It is therefore another aspect of the present invention to provide a photothermographic recording material capable of higher image gradation without significant deterioration in other photothermographic properties.
Other aspects and advantages of the present invention will become clear from the further description and examples
SUMMARY OF THE INVENTION
Surprisingly it has been found that thermal developability can be realized at lower temperatures without significant deterioration in other thermographic properties and images with higher gradation can be realized by using a mixture of particular substantially light-insensitive silver salts of monocarboxylic acids and particular light-insensitive silver salts of polycarboxylic acids. Particularly good results are obtained with a mixture of an equimolar mixture of silver glutarate and silver stearate.
According to the present invention a photothermographic recording material is provided comprising a support and a photo-addressable thermally developable element, the photo-addressable thermally developable element containing a mixture of substantially light-insensitive silver salts of organic carboxylic acids with one or more carboxylic acid groups, an organic reducing agent for the mixture of substantially light-insensitive organic silver salts in thermal working relationship therewith, a photosensitive silver halide in catalytic association with the mixture of substantially light-insensitive organic silver salts and a binder, wherein the mixture of substantially light-insensitive organic silver salts contains a silver salt of a monocarboxylic acid and a compound exclusive of silver succinate represented by formula (I):
AgOOC—R
1
—COOAg
wherein R
1
is a straight chain saturated or unsaturated hydrocarbon group with two or three carbon atoms, optionally substituted with one or more of ═O, ═S, ═CR
2
R
3
, an alkyl group, an aryl group, an amino group, a substituted amino group, a cycloalkyl group, a hydroxy group, a thiol group, an alkyl sulphone group, an aryl sulphone group, an alkoxy group, an acyloxy group, a thioalkyl group, a thioaryl, a carbamic ester group, a halogen atom or a —(C═O)R
4
group; wherein if R
1
is substituted with two substituents selected from the group consisting of alkyl, thioalkyl, substituted amino and alkoxy groups the two substituents may jointly comprise the atoms necessary to complete a carbocyclic or heterocyclic ring; R
2
and R
3
are independently hydrogen or an alkyl, substituted alkyl, hydroxy or thiol; R
4
is a hydroxy, —OAg, alkoxy, alkyl or —NHR
6
group; R
6
is hydrogen or an alkyl group.
According to the present invention a photothermographic recording material is also provided in an embodiment of the photothermographic recording material in which the photosensitive silver halide after exposure to UV, visible or IR light is capable of catalyzing or participating in photothermographic process.
A photothermographic recording process is also provided, according to the present invention, comprising the steps of: (i) providing a photothermographic recording material as referred to above; (ii) image-wise exposing the photo-addressable thermosensitive element with actinic radiation; (iii) bringing the image-wise exposed photothermographic recording material into proximity with a heat source; (iv) uniformly
Agfa-Gevaert
Chea Thorl
Leydig , Voit & Mayer, Ltd.
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