Photothermographic material

Details Photothermographic material Photothermographic material

2001-09-24

2004-07-13

Chea, Thorl (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Radiation sensitive product

Silver compound sensitizer containing

C430S600000, C430S609000, C430S613000, C430S619000

Reexamination Certificate

active

06762016

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to photothermographic materials, and specifically those having an improved storage stability after heat development.
BACKGROUND OF THE INVENTION
Recently, in the medical field, it is earnestly demanded to reduce the volume of the processing solution waste from the viewpoints of environment conservation and space saving. To achieve such a demand, technologies are necessary that relate to photothermographic materials used for medical diagnosis and photographic applications, which materials can be efficiently exposed with laser image-setters or laser imagers to form crisp black images of high resolution as well as superior sharpness. Such photothermographic materials eliminate the use of solution type processing chemicals and therefore can provide customers with heat development systems that are simple and environmentally friendly.
Although similar requirements exist also in the field of general image-forming material, medical images must have not only a high image quality excellent in sharpness and graininess as fine descriptions are required, but also are characteristically expected to look blue black for the ease of diagnosis. At present, there is no medical image output system that satisfies the above requirements, though a variety of hardcopy output systems are in practical use for general image formation including inkjet and electrophotographic printers which form images made of pigments or dyes.
On the other hand, thermographic image-recording systems are known as described in, for example, U.S. Pat. Nos. 3,152,904 and 3,457,075, p.279, Chapter 9 of “Thermally Processed Silver Systems” written by D. Klosterboer (Imaging Processes and Materials, Neblette's 8th edition), edited by J. Sturge, V. Walworth and A. Shepp (1989). Generally, a photothermographic material comprises a photosensitive layer comprising a photo-catalyst (such as silver halide) in a catalytic activity quantity, a reducing agent, a reducible silver salt (such as an organic silver salt) and, if needed, a color controlling agent that controls the tone of the silver, all dispersed in a binder matrix. Such a photothermographic material that has been subjected to an image exposure is heated to an elevated temperature (e.g., 80° C.), causing a redox reaction between the silver halide or the reducible silver salt (acting as an oxidant) and the reducing agent to give rise to a black image made of silver. The redox reaction is promoted by the catalytic action of the latent image in the silver halide formed by the exposed light. Accordingly, a black silver image is formed at an exposed area. Techniques related to such materials and image-forming methods are disclosed in many references such as U.S. Pat. No. 2,910,377 and JP-B-43-4924 (The term “JP-B” as used herein means an “examined Japanese patent publication”).
As no fixing processing is carried out after heat development for such photothermographic material, the thermally reactive organic silver salt and the reducing agent remain intact in the photosensitive material. These ingredients tend to cause a drawback that the background areas of the heat-developed material turn colored during prolonged storage after processing.
In photothermographic materials, an o-bisphenol compound is often utilized as the reducing agent, as the compound has a desirably high reactivity, as described in, e.g., EP-A-0803764, JP-A-51-51933 and JP-A-6-3793 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”). To impart a sufficiently high heat developablity to the photothermographic material, it is effective to incorporate therein a highly active reducing agent. However, the activity of the reducing agent usually conflicts with the storability of image after processing. Therefore, it has been difficult to simultaneously achieve a high heat developability and a good image storability by selecting the reducing agent alone. Under such circumstance, a new technique of improving image storability has been urgently demanded.
SUMMARY OF THE INVENTION
By taking into consideration the conventional demand described above, the purpose of the invention is to provide a photothermographic material that develops a sufficiently high image density with a feasible reaction temperature and time, and that shows a suppressed trend of coloration at the background area in a prolonged storage after processing.
As a result of their extensive study, the present inventors have found that the use of an oxazoline compound in the photothermographic material is quite effective to achieve the above-described purpose, and have applied this invention.
The invention is to provide a photothermographic material comprising a support having provided on at least one side thereof a photosensitive silver halide, a photo-insensitive organic silver salt, a reducing agent for silver ion and a binder, wherein at least one layer constituting said photothermographic material comprises an oxazoline compound.
The oxazoline compound used in the photothermographic material of the invention is preferably a compound having two or more 2-oxazolyl groups represented by the following formula (1) in the molecule thereof, or a polymer that has in the side chain thereof a 2-oxazolyl group represented by formula (1):
wherein R
1
, R
2
, R
3
and R
4
each independently represents a hydrogen atom, a halogen atom, an alkyl group or an aryl group, and the alkyl group or the aryl group may have a substituent.
In the photothermographic material of the invention, at least one of constitution layer or layers provided on the same side of the support as the layer comprising the photo-insensitive organic silver salt preferably comprises the oxazoline compound. In particular, it is preferable that the layer comprising the photo-insensitive organic silver salt and one or more layer selected from layer or layers adjacent thereto comprises the oxazoline compound.
DETAILED DESCRIPTION OF THE INVENTION
In the following, the photothermographic material of the invention will be explained in detail.
The photothermographic material of the invention comprises a support having provided on at least one side thereof a photosensitive silver halide, a photo-insensitive organic silver salt, a reducing agent for silver ion and a binder. And, as a feature of the photothermographic material of the invention, the material comprises an oxazoline compound in at least one layer constituting the material.
The oxazoline compound used in the invention can be selected from compounds having an oxazolyl group in the molecule. The oxazolyl group may be 2-oxazolyl group, 3-oxazolyl group or 4-oxazolyl group, and 2-oxazolyl group is preferred. The hydrogen atom in these oxazolyl groups may be substituted. No special restriction is imposed on the number of oxazolyl groups present in the oxazoline compound used in the invention, but two or more groups are preferably involved in the molecule, whereby the oxazolyl groups may be the same or different. No special restriction is imposed on the remaining part of the molecule except the oxazolyl group inasmuch as the advantageous features of the invention are realized.
The oxazoline compound used in the invention is preferably a compound having two or more 2-oxazolyl groups, represented by the following formula (1) in the molecule,
wherein R
1
, R
2
, R
3
and R
4
each independently represents a hydrogen atom, a halogen atom, an alkyl group or an aryl group, and the alkyl group or the aryl group may have a substituent.
More specifically, the preferable oxazoline compounds used in the invention are classified into two classes based on molecular weight and the presence or absence of recurring structure; i.e., (1) low molecular weight compounds having two or more 2-oxazolyl groups and (2) polymeric compounds obtained by homopolymerizing a monomer unit containing a 2-oxazolyl group or copolymerizing such a monomer with other monomer unit(s) copolymerizable with the 2-oxazolyl group-containing monomer.
Each class will be explained in detail below, but t

Affiliated with

Also associated with

Rating

Photothermographic material does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Photothermographic material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photothermographic material will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3231626