Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-03-03
2002-04-30
Chea, Thorl (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S531000, C430S607000, C430S611000, C430S613000, C430S617000, C430S955000, C430S957000
Reexamination Certificate
active
06379880
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat-developable photosensitive material capable of forming image by heat development without an aid of developing solution, and in particular to a heat-developable photosensitive material with less temperature dependence in heat development, stable performance against fluctuation in heat development conditions, and high gradation hardness.
BACKGROUND OF THE INVENTION
Recording materials capable of forming image by heat development process are described in U.S. Pat. Nos. 3,152,904 and 3,457,075, and in “Imaging Processes and Materials”, Neblette's 8th edition (1969), p.279-291. Heat-developable recording materials disclosed in these literatures contain reducible silver source (e.g. organic silver salt), a catalytic amount of photocatalyst (e.g. silver halide), color-tone adjuster for controlling tone of silver, and reducing agent, all of which are dispersed in a binder. While these heat-developable photosensitive materials are stable at room temperature, they produce blackened silver when heated, after light exposure, to a high temperature (e.g. 120° C.) through redox reaction between the reducible silver source and the reducing agent. This reaction is promoted by a catalytic action of latent image generated by the exposure.
Such recording materials for heat development are increasingly attracting attention as the ones to be combined with, for example, a laser image forming apparatus, since an image forming process using such materials requires no processing liquid such as developing solution but only heating, and therefore generates neither sulfurous acid gas nor ammonia gas. The laser image forming apparatus is utilized in medical, printing plate making, industrial and many other fields.
In general, a temperature of 100° C. or above and a heating time of 10 to 60 seconds are required to develop these heat-developable photosensitive materials. A variety of heat development apparatus has been proposed to enable such development. Known types of the apparatus include such that contacting a photosensitive material with a heat plate or heat roller to heat it by heat conduction; such that heating the material by passing it through an oven; such that generating heat within a layer of the material using electromagnetic wave; and such that using heat generated by current supply to a resistor substance (e.g. carbon black).
In all cases for using these apparatuses, it is critical to keep an entire surface of the photosensitive material layer at an uniform temperature, so that various approaches have been made for the heat development apparatuses. The uniformity of the temperature can, however, only be controllable within ±0.5° C. in practice. Keeping the temperature uniformity may become more difficult for a case with photosensitive material for printing plate making, since more wider area of so-called A-1 size (594×841 mm) or B-1 size (728×1030 mm) may be developed. It is thus desirable that the photosensitive material has a relatively wide latitude against fluctuations in the development temperature.
In recent years, a material based on infectious development by an ultrahigh contrast agent is under investigation as a heat-developable photosensitive material for printing plate making. A problem, however, emerged that the super gradation hardness is quite sensitive to fluctuations in heat development temperature. Changes in super gradation hardness may alter halftone dots' density and line width, so that basic performance of heat-developable photosensitive material for printing plate making cannot be satisfied. It is thus critical to improve the temperature dependence in heat development for a successful use of the heat-developable photosensitive material in such field.
Gradation hardeners for producing high-contrast image ever known include acylhydrazine derivatives disclosed in U.S. Pat. No. 5,464,738, U.S. Pat. No. 5,512,411, U.S. Pat. No. 5,496,695 and U.S. Pat. No. 5,536,622;
acrylonitrile derivatives disclosed in U.S. Pat. Nos. 5,545,515 and 5,635,339; malondialdehydes disclosed in U.S. Pat. No. 5,654,130; and isoxazoles disclosed in U.S. Pat. No. 5,705,324. Known compounds for accelerating development include amine compounds disclosed in U.S. Pat. No. 5,545,505; hydroxamic acids disclosed in U.S. Pat. No. 5,545,507; and hydrogen atom donors disclosed in U.S. Pat. No. 5,637,449, all of which are added to an image-forming layer together with the ultrahigh contrast agents.
There has, however, been a sustained need for creating a more advancing heat-developable photosensitive material capable of being stably developed.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a solution for the above-described problems. That is, the present invention is aimed at providing an improved heat-developable photosensitive material, and more specifically, a heat-developable photosensitive material capable of being stably developed. In more detail, the present invention is aimed at providing a heat-developable photosensitive material having less dependence on development temperature, retaining stable property against fluctuations in heat development conditions and having a high gradation hardness.
The present inventors found out, after extensive studies, that an excellent heat-developable photosensitive material producing a desired effect is obtainable by using a precursor for photographically useful compound capable of releasing the photographically useful compound when heated at specific temperatures, which has led us to the present invention.
That is, the present invention provides a heat-developable photosensitive material comprising: (a) at least one layer of photosensitive image-forming layer containing an organic silver salt, a photosensitive silver halide, a reducing agent and an organic binder; and (b) a functional layer containing a binder and a solid dispersion; the binder consisting of a water-dispersed thermoplastic resin, and the solid dispersion being made of a precursor of a photographically useful compound capable of releasing the photographically useful compound when heated to 100° C. or higher and not higher than heat development temperature.
The photographically useful compounds is preferably a development inhibitor or development accelerator. The heat-developable photosensitive material of the present invention preferably contains an ultrahigh contrast agent, and the organic binder in the photosensitive image-forming layer is preferably produced from a water-dispersed thermoplastic resin. The functional layer preferably contains a photosensitive silver halide.
The precursor of the photographically useful compound is preferably selected as either of the compounds having formulae (1) or (2) below:
R
10
—CHR
11
—CR
12
R
13
—A
11
(1)
(where, R
10
represents an electron attractive group, R
11
, R
12
and R
13
independently represent a hydrogen atom, alkyl group which may be substituted, or aryl group which may be substituted, and A
11
represents a photographically useful group bonded through a hetero atom),
R
21
—S—SO
2
—R
22
(2)
(where, R
21
and R
22
independently represent an aliphatic hydrocarbon group, aryl group, alkoxycarbonyl group, aryloxycarbonyl group or heterocyclic group, all of which may be substituted).
The heat-developable photosensitive material of the present invention is less dependent on development temperature, less sensitive to temperature nonuniformity in a heat developing apparatus, and capable of stable production of uniform image. In particular, the material is exceptionally useful since it can afford image with super gradation hardness and uniformity favorable to printing plate making.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments and specific ways of practicing the heat-developable photosensitive material of the present invention will be explained in detail hereinafter.
The heat-developable photosensitive material of the present invention is characterized in that comprising: (a) at least one layer of ph
Birch & Stewart Kolasch & Birch, LLP
Chea Thorl
Fuji Photo Film Co. , Ltd.
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