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
1999-09-09
2002-10-22
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
Reexamination Certificate
active
06468711
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a novel photosensitive composition, particularly, a photosensitive composition having high sensitivity and excellent stability. More specifically, the present invention relates to a photosensitive composition comprising a novel photopolymerization initiating systems which has excellent sensitivity to light over a wide region of the from 350 to 450 nm emitted from a InGaN-type semiconductor laser or the like. Furthermore, the present invention relates to photosensitive composition as an excellent material for a lithographic printing precursor, particularly a lithographic printing precursor capable of manufacturing a lithographic printing plate by scan exposure based on digital signals.
In addition, the present invention also relates to a method for manufacturing a lithographic printing plate. Specifically, the present invention related to a method for manufacturing a lithographic printing plate which is favored with good profitability, high productivity and excellent workability in the printing process and which can be manufactured by the scan exposure based on digital signals.
BACKGROUND OF THE INVENTION
Heretofore, PS plates having a structure such that a lipophilic photosensitive resin is provided on a hydrophilic support have been widely used for the lithographic printing plate. The PS plate is usually subjected to mask exposure (surface exposure) through a lith film and thereafter, the non-image area is dissolved and removed to obtain a desired printing plate.
In recent years, digitization technique is prevailing, where image information is electrically processed, stored and output. To cope With such digitization technique, various image output methods are newly put into practice. As a result thereof, computer-to-plate (CTP) technique of scanning light having high directivity such as laser ray according to digitized image information and thereby directly manufacturing a printing plate without having intervention of lith film is keenly demanded. To this purpose, there have been important technical problems to obtain a photosensitive composition, a lithographic printing precursor and a plate-making method, suitable therefor.
Among conventional CTP systems, a photosensitive material containing a photopolymerization system using titanocene as a photoinitiator is excellent and in particular, a combination with a carbomerocyanine-base dye described in JP-A-8-272096 and JP-A-8-262715 is known. However, this system has a problem in that the light source used is a visible light source having a relatively long wavelength, such as Ar laser (488 nm) and FD-YAG laser (532 nm), therefore, a photosensitive material having high sensitivity in the vicinity of 500 nm is used. Because of this, all works such as taking out of a plate from a corrugated fiberboard box, loading of the plate into a cassette of a plate setter and insertion of the plate into the plate setter, are necessary to be done under dark red safelight. Thus, the workability is very bad and it is strongly demanded to construct a CTP system such that the plate can be worked under brighter yellow or white safelight.
On the other hand, the laser technology is making remarkable progress in recent years. For example, practical use of a semiconductor laser capable of continuous oscillation in the region of from 350 to 450 nm has been realized using an InGaN-system material. If a CTP system using such a short wave light source could be constructed, a photosensitive material having sensitivity in a shorter wavelength region and therefore, enabling working under brighter safelight may be used. The semiconductor laser is furthermore very preferred as a light source for CTP system because it can be inexpensively produced in view of the structure.
From these reasons, it is eagerly demanded in this industrial field to obtain a photosensitive composition, a lithographic printing precursor and a plate-making method, suitable for the CTP system using a relatively short-wave semiconductor laser of from 350 to 450 nm.
Furthermore, the technique for obtaining a photosensitive composition having high sensitivity to She short-wave semiconductor laser region of from 350 to 450 nm is important and the demand therefor is more and more increasing not only in the field of CTP but also in other industrial fields over a wide range, for example, in the field of laser imaging such as photofabrication, holography and color hard copy, in the field of electric material production such as photoresist, and in the field of photocurable resin material such as ink, paint and adhesive.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel photosensitive composition having high sensitivity to the wavelength of from 350 to 450 nm.
Another object of the present invention is to provide a photosensitive composition which ensures, when used in the photosensitive layer or the like of a scan exposure lithographic printing plate, high sensitivity to the oscillation wavelength of an inexpensive short wave semiconductor laser, good workability, high profitability and suitability for the CTP system.
A yet other object of the present invention is to provide a method for manufacturing by scan exposure a lithographic printing plate suitable for CTP system, in which excellent workability and profitability are ensured and an inexpensive short wave semiconductor laser can be used.
Other objects and effects of the present invention will become apparent from the following description.
As a result of extensive investigations to attain these objects, the present inventors have found that a photosensitive composition containing a photoinitiation system using a combination with a specific compound exhibits sufficiently high sensitivity to the oscillation wavelength of a short-wave semiconductor laser and can be worked under bright light. The present invention has been accomplished based on this finding.
That is, the above-described objects of the present invention have been achieved by providing the following compositions and methods.
1) A photosensitive composition comprising:
a titanocene compound; and
at least one dye selected from: carbonyl compounds represented by formula (I):
wherein Y
0
represents a nonmetallic atom group for forming a nitrogen-containing heterocyclic ring together with the adjacent N and carbon atom, and X represents a monovalent nonmetallic atom group; and merocyanine compounds represented by formula (II):
wherein A represents S atom or NR
1
, R
1
represents an alkyl group or an aryl group, Y represents a nonmetallic atom group for forming a basic nucleus of the dye together with the adjacent A and carbon atom, X
1
and X
2
each independently represents a monovalent nonmetallic atom group, and X
1
and X
2
may be combined with each other to form the acidic nucleus of a dye.
2) The photosensitive composition according to the above 1), wherein said dye is a carbonyl compound of formula (I).
3) The photosensitive composition according to the above 2), further comprises an addition polymerizable compound having at least one ethylenically unsaturated double bond.
4) The photosensitive composition according to the above 1), wherein said dye is a merocyanine compound of formula (II).
5) The photosensitive composition according to the above 4), further comprises an addition polymerizable compound having at least one ethylenically unsaturated double bond.
6) The photosensitive composition according to the above 4), wherein said merocyanine compound is represented by the following formulae (II-2), (II-3) or (II-4):
wherein A and Y have the same meanings as in formula (II), X
3
, X
4
and Z each independently represents O atom, S atom or NR
5
, R
5
represents an alkyl group or an aryl group, R
2
represents hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylamino group or an arylamino group, R
3
represents hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, an aryloxy group, an alkylthio group, an
Higashi Tatsuji
Kawamura Koichi
Sorori Tadahiro
Baxter Janet
Burns Doane , Swecker, Mathis LLP
Gilmore Barbara
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