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
2002-02-13
2004-06-08
Ashton, Rosemary (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
C430S270100, C430S287100, C430S302000, C430S914000
Reexamination Certificate
active
06746820
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a light-sensitive composition and a light-sensitive lithographic printing plate. More specifically to a light-sensitive composition which is capable of forming an image by scanning exposure such as laser, etc., and suitable for forming a lithographic printing plate, a resist for forming a printed wiring board, a color filter or a phosphor pattern, etc., further specifically to a negative type light-sensitive lithographic printing plate using a light-sensitive composition.
2. Prior Art
It has been known a conventional light-sensitive resin in which sensitization is carried out by exposing a material to ultraviolet ray, and then, image formation is carried out, and a lithographic printing plate utilizing the light-sensitive resin. In addition to the above, a high sensitivity light-sensitive resin system has been developed, in which a sensitivity to light at visible light region has been markedly improved. In the above system, light sources such as argon ion laser (488 nm) or FD-YAG (532 nm), etc. have been utilized, and an image has directly been drawn by these lasers and a printing plate has been practically made. In these systems, the light-sensitive resin composition comprises a photopolymerization initiator, a dye sensitizer and a polymerizable compound. A photo energy absorbed by the dye sensitizer is utilized for radical cleavage of the photopolymerization initiator and the polymerizable compound is polymerized by the generating radicals.
A high output semiconductor laser or YAG laser which emits at a region of 750 nm or higher has been utilized as a light source for exposure in addition to a visible light laser. Thus, development of a light-sensitive material which uses an output of these light source and a printing plate utilizing the light-sensitive material have been extensively made.
With regard to a specific combination of a photopolymerization initiator and a sensitizer which constitute the above-mentioned photopolymerization system, there may be mentioned, for example, a combination of an organic boron anion and a cationic dye as disclosed in Japanese Provisional Patent Publications No. 143044/1987, No. 150242/1987, No. 5988/1993 and No. 89455/2000. As the other example of the photopolymerization initiator, there may be mentioned a combination of a titanocene compound and a sensitizer as disclosed in Japanese Provisional Patent Publication No. 221110/1988. Moreover, a combination of trihaloalkyl-substituted triazine compound and a cyanine dye has been disclosed in Japanese Provisional Patent Publication No. 189548/1990 and a combination of a hexa-aryl bi-imidazole compound and a dye has been disclosed in Japanese Provisional Patent Publication No. 279903/1989, etc.
However, in the various photopolymerization systems as mentioned above, it is the present status that a sufficient sensitivity has not yet been obtained. Accordingly, it has earnestly been desired to provide a light-sensitive composition which gives a high sensitivity stably. In particular, it has been desired to develop a high sensitivity light-sensitive material which is responsible for various kinds of laser exposure (scanning exposure) and a lithographic printing plate using the same.
Also, as other problem of the light-sensitive composition as mentioned above, when it is applied to, for example, a lithographic printing plate, there is a problem that scumming at a non-image portion is likely caused at the time of printing by preserving with a lapse of time.
On the other hand, there are disclosed that a hindered amine type compound is used as an antioxidant to improve preservation stability of a light-sensitive material as disclosed in Japanese Provisional Patent Publications No. 297364/1996, No. 244233/1997, No. 244234/1997, No. 52575/1999 and No. 214580/2000, etc. However, in the above-mentioned provisional patent publications, the constitution of the present invention is never disclosed and it has never been known that sensitivity can be improved by the combination of the present invention.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a light-sensitive composition having sufficient sensitivity. Another object of the present invention is to provide a light-sensitive composition having high sensitivity which can correspond to scanning exposure such as laser exposure, etc. Still further object of the present invention is to provide a lithographic printing plate having high sensitivity and causing no scumming after preservation for a certain period of time.
The above-mentioned object can be accomplished by a light-sensitive composition comprising a polymer comprising a carboxyl group-containing monomer having a polymerizable double bond at the side chain as a copolymerizable component, an organic borate salt, and a hindered amine type compound or a protonic acid captor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As the hindered amine type compound to be used in the present invention, a compound having at least one structural unit represented by the following formula (1) in the molecule can be mentioned as a representative one.
wherein R
1
, R
2
, R
3
and R
4
each represent a hydrogen atom, an alkyl group or an aryl group; Z represents an atomic group necessary for forming a nitrogen-containing aliphatic ring; Y represents a hydrogen atom, an alkyl group or an organic residue; among R
1
and R
2
, or among R
3
and R
4
, one of which may be incorporated into Z and provide a double bond.
Preferred examples of R
1
to R
4
may include an alkyl group having 1 to 6 carbon atoms. Preferred nitrogen-containing aliphatic ring structure may include piperidine, piperazine, morpholine, pyrrolidine, imidazolidine, oxazolidine, thiazolidine, selenazolidine, pyrroline, imidazoline, isoindoline, tetrahydroisoquinoline, tetrahydropyridine, dihydropyridine, dihydroisoquinoline, oxazoline, thiazoline, selenazoline, pyrrole, etc. Particularly preferred example may include piperidine, piperazine and pyrrolidine. Particularly preferred examples of the hindered amine type compounds having the structural unit represented by the above-mentioned formula (1) are shown below.
By the light-sensitive composition which is an objective of the present invention, i.e., by a light-sensitive composition comprising, in combination, a polymer comprising a carboxyl group-containing monomer having a polymerizable double bond at the side chain as a copolymerizable component, an organic borate salt, and a hindered amine type compound or a protonic acid captor, the present inventors have found that a sensitivity of the light-sensitive material is sufficiently improved. Also, by adding the above-mentioned hindered amine type compound, it can be found that a lithographic printing plate having high printing endurance without causing scumming at the time of preservation for a long term can be obtained.
An amount of the hindered amine type compound to be contained in the light-sensitive composition is preferably in the range of 0.1 mg to 500 mg per 1 m
2
of the light-sensitive material, more preferably in the range of 1 mg to 300 mg per 1 m
2
of the light-sensitive material.
Another embodiment of the present invention is a light-sensitive composition which comprises a polymer containing a monomer having a polymerizable double bond at the side chain and having a carboxyl group as a copolymer component, an organic borate salt as a photopolymerization initiator and a protonic acid captor in combination.
The protonic acid captor to be used in the present invention is a compound which forms a difficultly soluble salt by combining a protonic acid. There may be mentioned, for example, 3,4-dihydro-2H-pyrido (1,2-a)pyrimidin-2-one and a derivative thereof, and a compound represented by the following formula (2) can be preferably used.
wherein R
0
represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a carboxyamide group, a hydroxyl group or a condensed ring.
Preferred ex
Ashton Rosemary
Manelli Denison & Selter PLLC
Mitsubishi Paper Mills Limited
White, Jr. Paul E.
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