Positive type image forming material

Details Positive type image forming material Positive type image forming material

1998-11-27

2003-02-04

Chu, John S. (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Diazo reproduction, process, composition, or product

Composition or product which contains radiation sensitive...

C430S176000, C430S191000, C430S192000, C430S193000, C430S280100, C430S281100, C430S905000, C430S926000, C430S270100

Reexamination Certificate

active

06514656

ABSTRACT:

BACKGROUND OF THE INVENTION
1 Field of the Invention
The present invention relates to a positive type image forming material. More particularly, the present invention relates to a positive type image forming material which can be inscribed with a light such as a laser light, heat generated by irradiation with a laser light, heat imparted by a thermal heat and the like, as well as other means, and which is suitably used for a planographic printing plate. The present invention particularly relates to a positive type image forming material that is suitably used as a planographic printing plate wherein so-called direct production of a printing plate, is possible, using an infrared laser based on digital signals output from a computer or the like.
2 Description of the Related Art
In recent years, laser technologies have developed remarkably. In particular, high output and compact solid-state laser devices and semiconductor laser devices emitting infrared rays of a wavelength of 760 nm to 1,200 nm are readily available. These lasers are very useful as a light source for recording in the direct production of a printing plate from digital computer data. As an image recording (forming) material which can be recorded by such an infrared laser, there is a positive-type recording material described in E.P. No. 703499A1 in which a tetrahydropyranyl ester is used as an alkali-aqueous-solution-soluble polymer compound. Japanese Patent Application Laid-Open (JP-A) No. 310148/1996 describes positive type recording material which is subjected to abrasion with an ultraviolet laser. However, plate materials using these image-recording materials have problems in that when an image is formed, and printing is conducted after storage of the plate at high temperatures and high humidity, image-forming ability is reduced severely, and scratch resistance in an image portion is lowered.
There is also suggested a method in which image forming is conducted by an infrared ray laser on a positive type image forming material prepared by allowing an alkali-aqueous-solution-soluble polymer compound to contain an infrared ray absorbing agent and a substance which is capable of suppressing the solubility of the polymer compound in an alkali-aqueous-solution and is decomposed by light or heat (hereafter, this substance may be referred to as “light- and heat-decomposable substance”).
However, when these kinds of image recording materials are used, decomposition of the above-described heat and light decomposing substance can not be sufficiently effected; in other words, release or disappearance of the alkali-aqueous-solution-solubility-suppressing effect can not be sufficiently conducted by a laser having such an extent of energy as used for image forming. Therefore, a large difference can not be achieved between the alkali-aqueous-solution-solubilities of the irradiated portion and that of the no-irradiated portion (that is, only low sensitivity is achieved). As a result, image formation may not be excellent. To solve these problems, reducing the amount added of the above-described light- and heat-decomposable substance has been considered. However, in this case, since the alkali-aqueous-solution-solubility-suppressing effect decreases in the no-irradiation portion as well. A large difference still can not be achieved between the alkali-aqueous-solution solubilities of the irradiated portion and the no-irradiated portion, and excellent image formation can not be expected.
SUMMARY OF THE INVENTION
The present invention has been created in view of the problems described above, and an object thereof is to provide a positive type image forming material having excellent image forming property and excellent durability in printing, wherein direct image production is possible with infrared-ray-emitting solid-state or semiconductor laser devices or the like, based on digital data output from a computer or the like.
The above-described object of the present invention can be realized through the positive type image forming material described below.
A positive type image forming material comprising
A: an alkali-aqueous-solution-soluble polymer compound having a phenolic hydroxyl group,
B: a light and heat decomposing compound which suppresses alkali-aqueous-solution-solubility of said alkali-aqueous-solution-soluble polymer compound (A) having a phenolic hydroxyl group and is decomposed by light or heat to lose its alkali-aqueous-solution-solubility-suppressing effect on said compound (A), and
C: a cross-linkable compound which increases said solubility-suppressing effect of said compound (B) when used together with said component (B) in a composition containing the alkali-aqueous-solution-soluble polymer compound (A) having a phenolic hydroxyl group, and which has in its molecule two or more cross-linkable groups which are cross-linked with the alkali-aqueous-solution-soluble polymer compound (A) with heating.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in detail below.
<Compound which Enhances Above-described Alkali-aqueous-solution-solubility-suppressing Effect (Hereafter Refered to Simply as the “Solubility-suppressing Effects”) by Being Used Together with Above-described Component (B) in a Composition Containing Alkali-aqueous-solution-soluble Polymer Compound (A) Having a Phenolic Hydroxyl Group, and which Has in Its Molecule Two or More Cross-linkable Groups which are Cross-linked with Polymer Compound (A) with Heating>
First, a compound which enhances the above-described solution-suppressing effect by being used together with the above-described component (B) in a composition containing the alkali-aqueous-solution-soluble polymer compound (A) having a phenolic hydroxyl group, and which has in its molecule two or more cross-linkable groups which are cross-linked with the polymer compound (A) with heating (hereafter, referred to simply as a “cross-linkable compound(C)”), will be explained as a feature of the present invention.
This cross-linkable compound (C) is a substance which is added to improve the sensitivity of the positive type image forming material of the present invention, and which has a capacity of enhancing the solubility-suppressing effect of the light- and heat-decomposable substance (B). However, this cross-linkable compound does not itself have a capacity of substantially suppressing the alkali-aqueous-solution-solubility of the alkali-aqueous-solution-soluble polymer compound (A). When an image forming material containing the light- and heat-decomposable substance (B) and this cross-linkable compound (C) is irradiated with an infrared laser light, the light- and heat-decomposable substance (B) is decomposed and its solubility-suppressing effect disappears, while the cross-linkable compound (C) itself does not become a factor suppressing the alkali-aqueous-solution-solubility of the compound (A) at a laser-irradiated portion since the compound (C) does not have a solubility-suppressing effect.
On the other hand, at a non-laser-irradiated portion, the solubility-suppressing effect is enhanced more than it would be when only the light- and heat-decomposable substance (B) is used, due to interaction between the cross-linkable compound (C) and the light- and heat-decomposable substance (B).
The cross-linkable compound (C) in the present invention contains in its molecule a hetero atom, and can effect interaction such as hydrogen bond formation and ionic interaction and the like, with both the alkali-aqueous-solution-soluble polymer compound (A) and the substance (B) which is decomposed by light or heat to lose the above-described solubility-suppressing effect. Thus, the above-described solubility-suppressing effect is enhanced. The hetero atom contained in the cross-linkable compound (C) is not particularly restricted providing it is a hetero atom that can effect interaction such as hydrogen bond formation and ionic interaction and the like. In the present invention, atoms such as nitrogen, oxygen, fluorine, chlorine, bromine and the like having high electronegativ

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