Radiation imagery chemistry: process – composition – or product th – Thermographic process – Heat applied after imaging
Reexamination Certificate
2001-12-05
2004-01-27
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Thermographic process
Heat applied after imaging
C430S600000, C430S611000, C430S619000, C430S944000
Reexamination Certificate
active
06682878
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Present Invention
The present invention relates to a thermal development photosensitive material. More specifically, it relates to a thermal development photosensitive material suitable for medical diagnoses, industrial photography, printing and COM, and an image-forming method using the material.
2. Description of the Related Art
In recent years, for the sake of environmental conservation and space saving, a decrease in amounts of effluent has been in high demand in the fields of films for medical diagnosis and photolithographic films. Accordingly, technology of thermal development photosensitive materials as films for medical diagnosis and photoengraving films which can be exposed with a laser image setter or a laser imager more efficiently to form a clear black image having high resolution and sharpness has been required. With such thermal development photosensitive materials, a thermal development system which does not need solution-type processing chemicals and which can be handled more easily without environmental pollution can be supplied to clients.
There is also the same demand in the field of general image-forming materials. However, since images for medical diagnoses in particular require minute detailing, a high image quality excellent in sharpness and graininess is needed, and an image with a cool black tone is desired in view of easy diagnosis. Various hard copy systems using pigments and dyes, such as an ink jet printer, electrophotography and the like are currently being distributed as general imaging systems. Nevertheless, these are not satisfactory as an output system of medical images.
A thermal imaging system using an organic silver salt is described in, for example, U.S. Pat. Nos. 3,152,904 and 3,457,075 and D. Klosterboer, “Thermally Processed Silver Systems” (Imaging Processes and Materials, Neblette, 8th edition, compiled by J. Sturge, V. Walworth and A. Shepp, chapter 9, p. 279, 1989). Especially, a thermal development photosensitive material generally has a photosensitive layer in which a catalytic amount of a photo-catalyst (for example, a silver halide), a reducing agent, a reducible silver salt (for example, an organic silver salt) and, as required, a color matching agent for controlling the tone of silver are dispersed in a matrix of a binder. After exposure of an image, a thermal development photosensitive material is heated to a high temperature (for example, more than 80° C.), and a black silver image is formed by a redox reaction between a reducible silver salt (that acts as an oxidizer) and a reducing agent. The redox reaction is expedited by catalytic activity of a latent image of the silver halide generated through exposure. Accordingly, a black silver image is formed in an exposed area. This is disclosed in a large number of documents including U.S. Pat. No. 2,910,377 and Japanese Patent Publication No. 43-4924.
With the technological innovation and digitalization of recent years, thermal imaging systems with organic silver salts, which have been employed in output systems of medical images, have used a laser as an exposure light source. Further, the type of laser used is generally a semiconductor laser of an infrared wavelength, because laser power can be obtained at low cost.
A pure black tone is desired in an image for medical diagnosis. In these thermal imaging systems with organic silver salts, it is difficult to give a pure black tone, and the tone is controlled with the color matching agent. Nevertheless, the tone controlling has not been satisfactory, and improvement thereof has been called for.
In an infrared-sensitized thermal development photosensitive material, sensitivity is increased by using a hetero-aromatic mercapto compound or a hetero-aromatic disulfide compound as a strong sensitizer. When the amount of the mercapto compound or the disulfide compound is increased, the sensitivity is increased. However, the image tone is changed, and the pure black tone is hard to obtain. Thus, improvement has been called for.
SUMMARY OF THE PRESENT INVENTION
The present invention aims to attain the following upon solving the problems of the related art. That is, the present invention aims to provide a thermal development photosensitive material for use in medical imaging or photolithography which material gives an image with good tone (close to a pure black tone), and an image-forming method using the material.
The present inventors have assiduously conducted investigations to solve the problems, and have consequently found that a desirable thermal development photosensitive material which brings forth predetermined effects can be prepared using a combination of a specific reducing agent and specific compounds. This finding has led to the completion of the present invention.
Approaches to solve the problems are as follows.
The present invention discloses a thermal development photosensitive material having, on one surface of a substrate, at least one photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent for silver ions and a binder, the reducing agent including: (a) at least one of polyphenol compounds represented by the following formula (I); and (b) at least one of hindered phenol compounds represented by the following formula (II), wherein a molar addition ratio of the at least one compound represented by formula (II) to the at least one compound represented by formula (I) is from 0.001 to 0.2:
in which formula R
11
and R
11′
each independently represents an alkyl group having 1 to 20 carbon atoms; R
12
and R
12′
each independently represents a hydrogen atom or a substituent that is substitutable to a benzene ring; L represents —S— or —CHR
13
—; R
13
represents a hydrogen atom or an optionally substituted alkyl group having 1 to 20 carbon atoms; and X
1
and X
1′
each independently represents a hydrogen atom or a group that is substitutable to a benzene ring, and:
in which formula R
21
and R
22
each independently represents a hydrogen atom, an optionally substituted alkyl group or an optionally substituted acylamino group; neither of R
21
and R
22
is a 2-hydroxyphenylmethyl group; R
21
and R
22
are not both hydrogen atoms; R
23
represents a hydrogen atom or an optionally substituted alkyl group; and R
24
represents a substituent that is substitutable to a benzene ring.
In some embodiments, the present invention is the thermal development photosensitive material, wherein in formula (II), R
21
is an optionally substituted alkyl group.
In some embodiments, the present invention is the thermal development photosensitive material, wherein the photosensitive silver halide is infrared-sensitized.
In some embodiments, the present invention is the thermal development photosensitive material, wherein the molar addition ratio of the at least one compound represented by formula (II) to the at least one compound represented by formula (I) is from 0.005 to 0.1.
In some embodiments, the present invention is the thermal development photosensitive material, wherein at least one compound selected from hetero-aromatic compounds and hetero-aromatic disulfide compounds is further contained.
Further, the present invention discloses an image-forming method which includes exposing the thermal development photosensitive material to a laser having an exposure wavelength of 750 nm to 1,400 nm.
Moreover, the present invention discloses an image-forming method which includes processing the thermal development photosensitive material for a thermal development time of 5 to 20 seconds.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is described in detail below.
A reducing agent for silver ions to be used in the present invention is described below.
The thermal development photosensitive material of the present invention contains a reducing agent for an organic silver salt. The reducing agent for the organic silver salt may be any material (preferably an organic material) that reduces silver ions to metallic silver. Such
Fukui Kouta
Yoshioka Yasuhiro
Birch & Stewart Kolasch & Birch, LLP
Chea Thorl
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