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
2000-04-25
2002-01-01
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
C430S913000, C430S926000, C522S026000, C522S029000
Reexamination Certificate
active
06335144
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photosensitive composition containing a novel photopolymerization initiator, in particular, a photopolymerization initiator which is high sensitive and excellent in stability. In particular, the present invention relates to an excellent photopolymerizable composition or photosensitive composition as the material for a lithographic printing plate precursor capable of plate-making by scanning exposure based on digital signals. Besides the lithographic printing plate precursor, such a photopolymerizable composition or photosensitive composition are utilized in the fields of, for example, optical image-forming, holography, and a color hard copy, production of electronic materials such as photoresists, and photo-curable resin materials for inks, coatings and adhesions.
BACKGROUND OF THE INVENTION
As a lithographic printing plate, a PS plate comprising a hydrophilic support having provided thereon a lipophilic photosensitive resin layer has so far been widely used, and a desired printing plate is obtained by mask exposure (surface exposure) via a lith film and then dissolving and removing the non-image part.
Digitized techniques of electronically processing, accumulating and outputting image data using a computer have prevailed in recent years, and various image output systems corresponding to these digitized techniques have been put to practical use. As a result, a computer-to-plate (CTP) technique directly making a printing plate which comprises scanning digitized image data without using a lith film with high convergent light such as a laser beam is desired. With such a tendency, it has become an important technical subject to obtain the printing plate precursor well adapted to this purpose.
As one means to obtain a lithographic printing plate capable of such scanning exposure, the constitution in which a high speed photopolymerizable composition is used as the ink-receptive photosensitive resin layer (hereinafter referred to as “photosensitive layer”) provided on a hydrophilic support has so far been proposed and such printing plate is now on the market. The printing plate precursor having this constitution is easy to perform development process and, further, has desired properties as a printing plate and printing properties, e.g., excellent in resolving power, adhesion of ink, press life, and smearing prevention (i.e., staining prevention).
The photopolymerizable composition fundamentally comprises an ethylenically unsaturated compound, a photopolymerization initiator, and a binder resin. A photopolymerization initiator absorbs light to generate an active radical, addition polymerization of an ethylenically unsaturated compound is caused, and a photosensitive layer is not solubilized, thereby an image is formed. The greatest part of the conventional proposals concerning photopolymerizable compositions capable of scanning exposure have been those disclosed the use of a photopolymerization initiator having high photosensitivity, and many such compositions are described, e.g., in Bruce M. Monro et al.,
Chemical Revue,
93, 435 (1993) and R. S. Davidson,
Journal of Photochemistry and Biology A: Chemistry,
73.81 (1993).
With respect to conventionally used CTP systems using the photopolymerizable compositions comprising these photopolymerization initiators and long wavelength visible light sources such as Ar laser (488 nm) and FD-YAG laser (532 nm) as a light source, writing at higher speed has been desired for increasing the productivity of plate-making process but such technique is not realized yet because the output of light sources is not sufficiently high and the sensitivity of photosensitive materials is not sufficiently high.
On the other hand, in recent years, for example, a semiconductor laser using InGaN series materials and capable of continuous oscillation in the region of from 350 nm to 450 nm has nearly reached the stage of practical use. Scanning exposure systems using such short wave light sources have advantages that economical systems can be constructed while light sources have sufficient output as semiconductor lasers can be produced inexpensively from the structural point of view. Further, as compared with the systems using conventional FD-YAG and Ar lasers, photosensitive materials having the sensitive region of short wavelength which can be handled under brighter safelight can be used in this semiconductor laser.
Further, for example, as described in J. P. Faussier,
Photoinitiated Polymerization—Theory and Application,
Rapra Review, Vol. 9, Report, Rapra Technology (1998), and M. Tsunooka et al.,
Prog. Polym. Sci.,
21, 1 (1996), obtaining high speed photopolymerization initiators is an earnestly desired technique widely in imaging field.
Obtaining photopolymerization compositions having high photosensitivity to short wavelength semiconductor laser region of from 350 nm to 450 nm is an important technique which has been increasingly demanded widely in industrial fields of, other than CTP industry, for example, laser imaging such as optical shaping, holography, and a color hard copy, production of electronic materials such as photoresists, and photo-curable resin materials for inks, coatings and adhesions.
However, photopolymerization initiators which have sufficient sensitivity to scanning exposure in the region of short wavelength of from 350 nm to 450 nm have not been known up to the present.
As a relatively high speed photopolymerization initiator, photopolymerization initiators comprising a specific dye and a titanocene compound in combination are known. A combination of a dye having an oxazolidine acidic nucleus and triazine photopolymerization initiator is disclosed in JP-B-61-9621 (the term “JP-B” as used herein means an “examined Japanese patent publication”), but this compound is inferior in storage stability hence there are problems from the manufacturing point of view. Moreover, a combination of a dye having an oxazolone acidic nucleus and a titanocene compound is disclosed in JP-A-8-272096 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), and a combination of a dye having a 5-membered heterocyclic acidic nucleus and a titanocene compound is disclosed in JP-A-10-101719. These compounds are certainly high speed but not sufficiently and when laser light sources having wavelength of 450 nm or less are used, practicably sufficient sensitivity cannot be obtained and they are not suited to light sources of short wavelength
Further, combinations of a specific carbomerocyanine dye and a titanocene compound are disclosed in JP-A-9-328505, JP-A-8-272096 and JP-A-8-262715. They are certainly high speed but not practicably sufficient and they are not suited to light sources of short wavelength. Photopolymerizable compositions containing N-alkylindolylidene or N-alkylbenzothiazolylidenealkanone as a photosensitizer and hexaarylbiimidazoles as an activator are disclosed in JP-B-1-43299 and JP-A-2-216154, but these photopolymerizable compositions cannot exhibit practicably sufficient sensitivity and further there are problems in storage stability.
A combination of a carbazole derivative and a titanocene photopolymerization initiator is disclosed in JP-A-9-230913 but this compound has long absorption wavelength hence not suited to a light source of short wavelength. In JP-A-9-80750 is disclosed a combination of a styryl dye and a titanocene compound and this composition is certainly high speed but not sufficiently high. Combinations of a carbazole derivative and a triazine photopolymerization initiator are disclosed in JP-A-62-212643 and JP-A-63-32540, a combination of a carbazole derivative and an iodonium salt photopolymerization initiator in JP-A-63-32539, and a combination of a carbazole derivative and a thioxanthone photopolymerization initiator is disclosed in JP-A-63-325401, but the sensitivity of any of these compounds is practicably insufficient and further there are problems in storage stability.
SUMMARY OF THE INVENTION
An object of the present inve
Murota Yasufumi
Sorori Tadahiro
Ashton Rosemary
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
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