Photothermographic material

Details Photothermographic material Photothermographic material

2003-04-15

2004-10-05

Chea, Thorl (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Radiation sensitive product

Silver compound sensitizer containing

C430S264000, C430S598000

Reexamination Certificate

active

06800431

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a photothermographic material and an image recording method by use thereof.
PRIOR ART
In the field of graphic arts and medical treatment, there have been concerns in processing of photographic film with respect to effluents produced from wet-processing of image forming materials, and recently, reduction of the processing effluent is strongly demanded in terms of environmental protection and space saving. There is known a technique, as described in U.S. Pat. Nos. 3,152,904 and 3,487,075, and D. Morgan, “Dry Silver Photographic Materials” (Handbook of Imaging Materials, Marcel Dekker, Inc. page 48, 1991). Photographic material used in such a technique is developed at a temperature of 80° C. or higher, which is called photothermographic material.
The photothermographic material contains relatively large amounts of chemical substances so that the thickness of a light-sensitive layer or light-insensitive layer tends to increase. As a result, a loner time is required in the stage of coating or drying in the manufacture of the photothermographic material, lowering productivity.
As is known in the photographic art, reducing silver coverage is effective in reducing the layer thickness. However, simply reducing the silver coverage results in unfavorably reduced image density. To allow the image density not to be reduced, it is effective to increase the number of developing initiating points per unit area, increasing covering power. In conventional photographic materials used in graphic arts, so-called infectious development by using nucleating agents is employed to increase covering power, whereby relatively high image densities can be achieved even at a low silver coverage. For example, JP-A Nos. 10-512061 and 11-511571 disclosed such a technique (hereinafter, the term, JP-A refers to unexamined Japanese Patent Application Publication). However, it was proved that photothermographic materials containing commonly known nucleating agents are inferior in storage stability and often form yellowish silver images. Such images adversely affect diagnosis specifically for used medical check and are not suitable. There was also a defect that slight change in thermal development temperature or time easily caused appreciable variation in image density.
SUMMARY OF THE INVENTION
The present invention has been achieved in view of the foregoing problems. Thus, it is an object of the present invention to provide a photothermographic material exhibiting superior storage stability, an enhanced maximum density, reduced fogging and improved silver image tone, and having improved latitude for variation in thermal developing conditions; and an image recording method by the use thereof.
The foregoing object can be accomplished by the following constitution:
1. A photothermographic material comprising on a support an organic silver salt, light-sensitive silver halide and a reducing agent for silver ions, wherein the reducing agent is a compound represented by the following formula (1):
wherein R
1
through R
4
are each independently an alkyl group, at least one of R
1
through R
4
is an alkyl group containing a hydroxy group or a group capable of forming a hydroxy group upon deprotection; L
1
is —S— or —CR
55
(R
66
)—, in which R
55
and R
66
are each a hydrogen atom, an alkyl group, a 3- to 10-membered non-aromatic ring group, an aryl group or a heteroaryl group; X
1
and X
2
are each a group capable of being substituted on a benzene ring; and n and m are each an integer of 0 to 2;
2. The photothermographic material as described in 1 or 2, wherein the reducing agent represented by formula (1) is represented by the following formula (2):
wherein R
1
, R
4
, L
1
, X
1
, X
2
, n and m are each the same as defined in formula (1); R
5
and R
6
are a hydrogen atom or an alkyl group; p and q are each an integer of 0 to 5;
3. The photothermographic material as described in 1 or 2, wherein the photothermographic material comprises a silver-saving agent;
4. The photothermographic material as described in any of 1 through 7, wherein the silver-saving agent is represented by the following formula (X):
wherein R
1x
and R
2x
are each a hydrogen atom or a substituent; X
1x
is —S—, —O— or —N(R
3x
)—, in which R
3x
is a hydrogen atom or substituent; nx is 2 or 3; mx is an integer of 1 to 3; X
2x
is a ballast group, an adsorption group onto silver halide or a silyl group; qx is an integer of 1 to 3; and Lx is a di- to hexa-valent linkage group;
5. An image recording method, wherein a photothermographic material as described above is exposed using a laser light scanning exposure apparatus having an oscillation wavelength of 600 to 1200 nm; and
6. The image recording method as described above, wherein the scanning laser light is longitudinally multiple.
DETAILED DESCRIPTION OF THE INVENTION
One feature of the photothermographic material relating to this invention is that the reducing agent for silver ions is a specific bisphenol derivative, which is used alone or in combination with other reducing agents differing in chemical structure. Such constitution has unexpectedly inhibited deteriorations in performance during storage, such as fogging and deterioration in thermally developed silver image tone during storage.
Further, when used in combination with a silver-saving agent, there were achieved surprising effects such as enhanced maximum density, superior silver image tone and superior images resistant to variation in process. Specifically, the use of the silver-saving agent represented by the formula (X) described later has resulted in markedly advantageous effects.
The reducing agents usable in this invention are preferably bisphenol derivatives represented by the formula (1) or (2) described earlier.
The compound represented by formula (1) will be detailed. In formula (1), R
1
through R
4
independently represent an alkyl group and examples thereof include an alkyl group having 1 to 15 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, decyl, dodecyl, pentadecyl), a halogenated alkyl group (e.g., trifluoromethyl, perfluorooctyl), and a cycloalkyl group (e.g., cyclopentyl, cyclohexyl, 1-methylcyclohexyl).
The foregoing groups may further be substituted. Examples of substituent groups include an alkyl group having 1 to 15 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, hexyl, decyl, dodecyl, pentadecyl), halogenated alkyl group (e.g., trifluoromethyl, perfluorooctyl), cycloalkyl group (e.g., cyclohexyl, cycloheptyl), alkynyl group (e.g., propargyl), glycidyl group, acrylate group, methacrylate group, aryl group, heterocyclic group (e.g., pyridyl, thiazolyl, oxazolyl, imidazolyl, furyl, pyrrolyl, pyrazinyl, pyrimidinyl, pyridazinyl, selenazolyl, sulforanyl, piperidinyl, pyrazolyl, tetrazolyl), alkoxy group (e.g., methoxy, ethoxy, propoxy, pentyloxy, cyclopentyloxy, hexyloxy, cyclohexyloxy) aryloxy group (e.g., phenoxy), alkoxycarbonyl group (e.g., methyloxycarbonyl, ethyloxycarbonyl, butyloxycarbonyl), aryloxycarbonyl group (e.g., phenyloxycarbonyl), sulfonamido group (e.g., methanesulfonamide, ethanesulfoneamido, butanesulfoneamido, hexanesulfoneamido, cyclohexanesulfoneamido), benzenesulfoneamido), sulfamoyl group (e.g., aminosulfonyl, methylaminosulfonyl, dimethylaminosulfonyl, butylaminosulfonylhexylaminosulfonyl, cyclohexylaminosulfonyl, phenylaminosulfonyl, 2-pyridylaminosulfonyl), urethane group (e.g., methylureido, ethylureido, pentlureido, cyclohexylureido, phenylureido, 2-pyridylureido), acyl group (e.g., acetyl, propionyl, butanoyl, hexanoyl, cyclohexanoyl, benzoyl, pyridinoyl), carbamoyl group (e.g., aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, propylaminocarbonyl, pentylaminocarbonyl, cyclohexylaminocarbonyl, phenylaminocarbonyl, 2-pyridylaminocarbonyl), amido group (e.g., acetoamide, propioneamido, btaneamido, hexaneamido, benzamido), sulfonyl group (e.g., methylsulfinyl, ethylsulfinyl, butylsulfonyl, cyclohexylsulfonyl, phenylsulfinyl, 2-pyridylsulfonyl), amino group (e.g.,

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