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
2000-03-08
2001-11-27
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
C430S288100, C430S926000, C522S031000, C522S060000, C522S063000, C522S075000
Reexamination Certificate
active
06322950
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a photosensitive composition which contains a novel photo-initiation system, particularly a photo-initiation system having high sensitivity and excellent stability. This invention also relates to a photopolymerizable composition which is particularly excellent as a material for use in the lithographic printing plate precursors, by which plate making can be effected by the scanning exposure based on digital signals.
BACKGROUND OF THE INVENTION
In the prior art, PS plates having a construction in which a lipophilic photosensitive resin layer is provided on a hydrophilic support have been broadly used as lithographic printing plates, and desired printing plates have been obtained generally a plate making method in which a masking exposure (surface exposure) is carried out via a lith film and then non-image parts are dissolved and removed.
In recent years, digitalization techniques in which image information is electronically treated, accumulated and output using a computer have been widely popularized, and various corresponding new image output systems have been put into practical use. As a result, there is a demand for a computer to plate (CTP) technique for directly producing a printing plate without mediating a lith film by scanning a high directivity light such as laser beam according to the digitized image information, and production of the printing plate precursors suited for such a technique therefore is now an important technical subject.
As one of the methods for obtaining such lithographic printing plates capable of effecting scanning exposure, a construction in which a photopolymerization system composition having excellent sensitizing speed is used as an ink-acceptable photosensitive resin layer (to be referred to as “photosensitive layer” hereinafter) to be provided on a hydrophilic support has been proposed and is already on the market. A precursor of such a construction renders possible simple and easy developing treatment and has desirable machine plate making and printing properties such as excellent resolution, inking property, printing durability and anti-scumming property.
The aforementioned photopolymerizable composition basically comprises an ethylenic unsaturated compound, a photopolymerization initiation system and a binder resin, and the image formation is effected by a process in which the photo-initiation system absorbs light to form an active radical which induces addition polymerization of the ethylenic unsaturated compound to cause insolubilization of the photosensitive layer. Most of the prior art proposals regarding photopolymerizable compositions capable of effecting scanning exposure disclose the use of photo-initiation systems having excellent photosensitivity and are described for example by Bruce M. Monroe et al. in
Chemical Review
, 93, 435 (1993) and by R. S. Davidson in
Journal of Photochemistry and Biology A: Chemistry
, 73, 81 (1993).
Regarding the background art CTP system which uses a photopolymerizable composition comprising such an initiation system and a long wavelength visible light source such as Ar laser (488 nm) or FD-YAG laser (532 nm) as the light source, writing at a more higher speed is expected for the purpose of improving productivity of the plate making step, but such a purpose has not been achieved yet because of insufficient output of the light source and insufficient sensitivity of the photosensitive material.
On the other hand, a semiconductor laser which uses, for example, an InGaN system material and can effect continuous oscillation at a range of from 350 nm to 450 nm has been put into practical steps in recent years. In the scanning exposure system which uses these short wavelength light sources, the semiconductor laser can be produced with low cost due to its structure, so that it is possessed of an advantage in that an economical system having sufficient output can be constructed. In addition, in comparison with the prior art system which uses FD-YAG or Ar laser, it renders possible the use of a photosensitive material which has a short wavelength photosensitive range and can be handled under a brighter safe light.
However, no information is available to date concerning a photo-initiation system having sufficient sensitivity for scanning exposure at a short wavelength region of from 350 nm to 450 nm.
In addition, as is described for example by J. P. Faussier in “Photoinitiated Polymerization—Theory and Applications”:
Rapra Review
vol. 9
, Report, Rapra Technology
(1998) and by M. Tsunooka et al. in
Prog. Polym. Sci
., 21, 1 (1996), construction of a photoinitiation system having high sensitivity is a technique still greatly expected in the imaging field. Since a photoinitiation system comprising a sensitizing dye and an activator can generate an acid or base in addition to the aforementioned active radical, by selecting the activator, it is used for example in the image formation such as optical image formation, holography or color hard copy, in the field of electronic material production such as of photo resists and in photo-curing resin materials such as ink, paints and adhesives. In these industrial fields, there is a demand for finding a sensitizing dye having excellent light absorption ability and sensitizing ability, in order to induce decomposition of the activator efficiently.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a photosensitive composition which uses a novel photo-initiation system having high sensitivity for a wide wavelength region of from 350 nm to 450 nm and is suited for lithographic printing plate precursors having high sensitivity for the oscillation wavelength of inexpensive short wave semiconductor lasers, for the purpose of obtaining a lithographic printing plate for scanning exposure use which is excellent in terms of workability and economy and suited for the CTP system.
Another object of the present invention is to provide a novel compound which can be used in the composition.
With the aim of achieving the above objects, the inventors of the present invention have conducted intensive studies and found as a result of the efforts that a novel photo-initiation system comprising a sensitizing dye having a specified structure and an activator compound can give particularly high photosensitive property.
Specifically, it was found that a photo-initiation system which comprises (i) a sensitizing dye represented by formula (I) and (ii) an activator compound that generates chemical changes by its interaction with an electronic excitation condition induced by light absorption of the sensitizing dye represented by the formula (I), thereby producing at least any one of radicals, acids and bases, has markedly high photosensitivity and shows high sensitivity particularly at a wavelength of approximately from 350 to 450 nm.
wherein A represents S atom or NR
7
, Y represents a non-metallic atomic group which forms a basic nucleus of the pigment together with the adjacent A and carbon atom, each of R
1
, R
2
, R
3
, R
4
, R
5
and R
6
independently represents a monovalent group of the non-metallic atomic group, and R
7
represents an alkyl group or an aryl group.
The above-described initiation system can provide an excellent photosensitive composition in combination with (iii) a compound whose physical or chemical characteristics are changed and maintained by undergoing reaction with at least one of radicals, acids and bases.
It was found also that a lithographic printing plate precursor which has sufficient sensitivity for scanning exposure by a short wave semiconductor laser, can be handled under a bright safe light and shows excellent printing ability can be obtained by the use of the photosensitive composition in which the compound (iii) whose physical or chemical characteristics are changed and maintained by undergoing reaction with at least any one of radicals, acids and bases is an addition-polymerizable compound having an ethylenic unsaturated double bond.
Also, in order to obtain the effects of the presen
Kawamura Koichi
Kunita Kazuto
Murota Yasubumi
Sorori Tadahiro
Ashton Rosemary
Burns Doane , Swecker, Mathis LLP
Fuji Photo Film Co. , Ltd.
LandOfFree
Photosensitive composition and 1,3-dihydro-1-oxo-2H-indene... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photosensitive composition and 1,3-dihydro-1-oxo-2H-indene..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photosensitive composition and 1,3-dihydro-1-oxo-2H-indene... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584500