Thermally developable photosensitive material

Details Thermally developable photosensitive material Thermally developable photosensitive material

2003-03-25

2004-08-24

Chea, Thorl (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Radiation sensitive product

Silver compound sensitizer containing

C430S598000, C430S607000, C430S603000, C430S610000, C430S619000, C430S620000

Reexamination Certificate

active

06780578

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermally developable photosensitive material. More specifically, the invention relates to a thermally developable photosensitive material that has fewer fluctuations involving sensitivity, gradation and silver color tone due to variation of temperature or duration of thermal development.
2. Description of the Related Art
Recently in medical fields, it has been strongly desired, from the standpoints of environmental protection and space-saving, to reduce the volume of processing waste fluids. Thus, there is a need for technologies relating to thermally developable photosensitive materials (heat development-type photosensitive materials) which can be efficiently exposed by a laser image setter or a laser imager to form clear black images having high resolution and sharpness. These thermally developable photosensitive materials are advantageous in providing customers with a thermal processing system that does not need liquid-type processing solutions, and which is simple and not harmful to the environment.
There is also a need for the same technologies in the field of ordinary image forming materials. In particular, in the field of medical diagnosis, which requires detail depiction, high quality images excellent in sharpness and graininess are needed and blue black image tone is desired in view of diagnosing readiness. Currently, various types of hard copy systems using pigments and dyes, for example, ink jet printers and electrophotographic systems are widely used as the ordinary imaging system. However, satisfactory systems for outputting images for use in medical diagnosis have not been developed.
On the other hand, thermally developable image forming systems using organic silver salts are described, for example, in U.S. Pat. Nos. 3,152,904 and 3,457,075, and in “Thermally Processed Silver Systems (Imaging Processes and Materials)” written by B. Shely, Neblette, 8th Ed., edited by J. Sturge, V. Walworth & A. Shepp, Chap. 9, p. 279, 1989. In general, thermally developable photosensitive materials have a photosensitive layer (image-forming layer) produced by dispersing a catalytically active amount of a photocatalyst (e.g., silver halide), a reducing agent, a reducible silver salt (e.g., organic silver salt), and optionally a toning agent for adjusting silver color tone in a binder matrix. Thermally developable photosensitive materials of this type are, after having been imagewise exposed, heated to an elevated temperature (for example, at 80° C. or higher) to form black silver images through redox reaction between a reducible silver salt (acting as an oxidizing agent) and a reducing agent. The redox reaction is accelerated by catalytic action of latent images which have been formed on silver halides exposed. Therefore, the black silver images are formed in the exposed area. This technique is disclosed in many references, such as U.S. Pat. No. 2,910,377 and Japanese Patent Application Publication (JP-B) No.43-4924, and as a result, Fuji Medical Dry Imager FM-DP L that utilizes the thermally developable photosensitive material is commercially available as an image-forming system for use in the medical field.
In the thermally developable photosensitive system, images are formed by silver grains which are generated at the time of heating due to a physical phenomenon, and a size or a size distribution thereof momentarily changes depending on a developing temperature or a developing time duration. Therefore, this system has a drawback in that in compliance with a fluctuation of the developing temperature or developing time duration, the size or the size distribution varies and, accordingly, sensitivity or graduation is fluctuated. Further, a silver color tone also changes depending on the temperature or time duration. Such a fluctuation or change of finished materials leads to a problematic matter of a lowered diagnostic ability at the time of diagnosis, and hence, an improvement is desired.
Various attempts have been made to reduce liability of the thermally developable photosensitive material to be influenced by developing conditions. Japanese patent Application Laid-Open (JP-A) No. 10-104780 describes that temperature dependency is improved when a mixture of two or more kinds of organic acid silvers is used. However, this method has a problem of deteriorated image storability. JP-A Nos. 2000-267222, 2001-92075 and 2001-264925 disclose use of a developing accelerator. However, a problem arises in this case that the image storability or the image color tone is impaired. JP-A No. 2000-321712 discloses a method to use a precursor that releases a developing inhibitor. However, this method involves problems of an unfavorable decrease in sensitivity and a reduced image density, and hence, this method has not been actually used. JP-A Nos. 10-62899, 10-186572 and EP-A No. 0,803,764 disclose that addition of a heterocyclic thione compound or a heterocyclic mercapto compound to an image-forming layer of the thermally developable photosensitive material serves to suppress development, augment spectrally sensitizing efficiency or improve storability before and after the thermally developable photosensitive material is developed. However, there has not yet been known any compound which can reduce liability of the thermally developable photosensitive material to be influenced by developing conditions, and the heterocyclic thione compound or the heterocyclic mercapto compound does not have such an effect.
In light of the above, there is a need for an improved thermally developable photosensitive material.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a thermally developable photosensitive material that reduces fluctuations of photographic performances such as sensitivity, gradation and silver color tone due to a variation of processing conditions such as a temperature or a time duration performing thermal development, and achieves a consistent finished quality even when a change in installing circumstances of a thermal developing apparatus and a change thereof with time arises.
The aforementioned object of the invention has been achieved using a thermally developable photosensitive material described below.
The present invention provides a thermally developable photosensitive material having a support, and comprising on at least one surface of the support a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for thermal development, a binder, and a compound represented by the following general formula (1):
wherein R
1
represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or a heterocyclic group; X represents a chalcogen atom; and Y represents an amino group, an N-alkylamino group, an N,N-dialkylamino group, an anilino group, a hydroxyl group, an alkoxy group, an aryloxy group, an acylamino group or a sulfonamide group, and
wherein when Y represents an alkoxy group, an alkylamino group, a dialkylamino group, an acylamino group or a sulfonamide group, Y and R
1
may be bonded to each other to form a 5- to 7-membered ring.
It is preferable that, in the general formula (1), X represents an oxygen atom or a sulfur atom; and Y represents a substituted or unsubstituted amino group, anilino group or acylamino group.
The compound represented by the general formula (1) is preferably an urea or a thiourea.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will be described in detail hereinafter.
1. Thermally Developable Photosensitive Material
A thermally developable photosensitive material according to the invention includes a support, and having disposed on at least one surface of the support, an image-forming layer comprising a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, a compound represented by a general formula (1) and a binder. Preferably, the thermally developable photosensitive material may include a surface protective layer on the image-forming layer, or may inc

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