Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2002-02-22
2003-11-11
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S286100, C430S287100, C430S348000, C430S964000
Reexamination Certificate
active
06645697
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a photopolymerizable composition and a photopolymerizable lithographic printing plate, particularly to a photopolymerizable composition and a photopolymerizable lithographic printing plate, which shows high sensitivity to light in long-wavelength regions.
BACKGROUND ART
Heretofore, as methods for forming images by exposure of photopolymerizable compositions, various methods have been known, such as, a method wherein a layer of a photopolymerizable composition comprising an ethylenically unsaturated compound and a photopolymerization initiator, or comprising an organic polymer binder material in addition to them, is formed on the surface of a support and then subjected to image exposure so that the ethylenically unsaturated compound at the exposed portion is polymerized and cured, and then the non-exposed portion is dissolved and removed to form a cured relief image, a method wherein a layer of a photopolymerizable composition is exposed to change the bond strength of the layer to the support, and then the support is peeled to form an image, and a method wherein a change in the adhesion of a toner to the layer of a photopolymerizable composition due to light, is utilized to form an image. As the photopolymerization initiator, one which is sensitive to light with a short wavelength within an ultraviolet region of at most 400 nm, has been used, such as benzoin, benzoin alkyl ether, benzyl ketal, benzophenone, anthraquinone, benzyl ketone or Michler's ketone.
On the other hand, in recent years, a photosensitive material showing high sensitivity to a light within a visible light range has been strongly demanded along with the development of the image-forming technology, and many photopolymerizable compositions have been proposed, whereby the sensitivity range has been broadened to about 500 nm corresponding to a laser printing plate making system employing an oscillation beam of an argon ion laser of 488 nm. Further, researches have been actively carried out on photopolymerizable compositions sensitive to a light within a long wavelength region exceeding 600 nm corresponding to a laser printing plate making system employing a He—Ne laser or a semiconductor laser or a copying technique for full color image.
For example, JP-A-62-143044 discloses a photopolymerizable composition comprising a dye cation-organic boron anion complex, and in examples of the dye cation-organic boron anion complex, a complex of an indole type cyanine dye cation with an organic boron anion, having a maximum absorption wavelength of 740 nm, is shown. Further, JP-2000-98602 discloses a photopolymerizable composition comprising a certain specific ethylenically unsaturated compound, a cyanine dye cation and an organic boron anion, which is sensitive to light in long-wavelength regions, and in examples of the cyanine type, a dye having a diphenylamino group as a substituent on the polymethine chain.
However, it is commonly known that with respect to the active radical-forming ability of a photopolymerization initiator, the sensitivity to a light with a wavelength exceeding 500 nm, particularly 600 nm, sharply decreases along with a decrease in the light excitation energy. To a light within such a long wavelength region, none of the conventional photopolymerizable compositions has been satisfactory from the viewpoint of the sensitivity, and in addition, there has been a problem that a photopolymerization reaction is likely to proceed during handling under a white fluorescent lamp, whereby it has been difficult to obtain a product of a uniform quality.
The present invention has been made in view of the above-described prior art, and it is an object of the present invention to provide a photopolymerizable composition and a photopolymerizable lithographic printing plate, which shows high sensitivity to a light in the visible light region or in a long wavelength region such as a near infrared region and which is insensitive to a light in the ultraviolet region and excellent in handling under a white fluorescent lamp.
DISCLOSURE OF THE INVENTION
The present inventors have conducted extensive studies to solve the above problems and as a result, have found it possible to accomplish the above object with a photopolymerizable composition containing a dye which has, as a basic structure, a structure having hetero atoms connected via a polymethine chain, and which has a certain specific substituent on the polymethine chain or on other basic structure. The present invention has been accomplished on the basis of this discovery.
Namely, the present invention provides a photopolymerizable composition comprising the following components (A), (B) and (C), and a photopolymerizable lithographic printing plate comprising a support and, formed on a surface thereof, a layer of the photopolymerizable composition:
(A) an ethylenically unsaturated compound;
(B) a dye which has, as a basic structure, a structure having hetero atoms connected via a polymethine chain and which is selected from the group consisting of the following (B-1), (B-2), (B-3) and (B-4):
(B-1) a dye having, on a polymethine chain, a substituent containing a chain ether bond which forms an oxonium cation or a chain thioether bond which forms a sulfonium cation, upon resonance in the dye molecule,
(B-2) a dye having, on a polymethine chain, two substituents forming a cyclic ether bond which forms an oxonium cation or a cyclic thioether bond which forms a sulfonium cation, upon resonance in the dye molecule,
(B-3) a dye having, on a polymethine chain, a substituent containing an amino-vinyl bond which forms an aminium cation upon resonance in the dye molecule, and
(B-4) a dye having, on a polymethine chain or other basic structure, a substituent containing an acid anion group, its ester group or a base; and
(C) a photopolymerization initiator.
BEST MODE FOR CARRYING OUT THE INVENTION
The ethylenically unsaturated compound of component (A) constituting the photopolymerizable composition of the present invention, is a monomer having an ethylenically unsaturated double bond which undergoes addition polymerization and, in some cases, undergoes crosslinking or curing, by an action of the photopolymerization initiator of component (C) which will be described hereinafter, when the photopolymerizable composition is irradiated with active light rays, or a polymer having such double bonds in its main chain or side chain. Here, the monomer is meant for a concept opposite to a so-called polymer, and it includes in addition to a monomer in a narrow sense, a dimer, a trimer and other oligomers.
Specifically, such monomers include, for example, (1) unsaturated carboxylic acids such as acrylic acid and methacrylic acid (these two acids may generally be referred to as “(meth)acrylic acid”), (2) alkyl esters of these acids, (3) esters of unsaturated carboxylic acids with aliphatic polyhydroxy compounds, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, trimethylol ethane tri(meth)acrylate, trimethylol propane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerol di(meth)acrylate, glycerol tri(meth)acrylate, and the corresponding itaconates, crotonates and maleates, (4) esters of unsaturated carboxylic acids with aromatic polyhydroxy compounds, such as hydroquinone di(meth)acrylate, resorcinol di(meth)acrylate, and pyrogallol tri(meth)acrylate, (5) condensates of polyhydroxy compounds, unsaturated carboxylic acids and polybasic carboxylic acids, such as a condensate of ethylene glycol, (meth)acrylic acid and phthalic acid, a condensate of diethylene glycol, (meth)acrylic acid and maleic acid, a condensate of pentaerythritol, (meth)acrylic acid and terephthalic acid, and a condensate of butane diol, glycerol, (meth)acrylic acid and adipic acid, (6) urethane (meth)acrylates, such a
Baxter Janet
Gilliam Barbara
Mitsubishi Chemical Corporation
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