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
2000-02-22
2003-07-29
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
C430S281100, C430S286100, C430S944000, C430S945000, C101S453000
Reexamination Certificate
active
06599674
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat-sensitive lithographic printing plate which can be used as a lithographic printing plate precursor (hereinafter occasionally referred to as “PS plate”). More particularly, the present invention relates to a heat-sensitive lithographic printing plate which can be subjected to treatment by various lasers emitting visible light or infrared rays according to digital signal to allow direct plate making, can be subjected to aqueous development or can be directly mounted on the printing machine for printing, and in particular, a heat-sensitive lithographic printing plate adapted for production of printing plate requiring no treatment.
BACKGROUND OF THE INVENTION
Heretofore, the production of a printing plate from a PS plate includes, steps subsequent to an exposure step, for example, a wet development step for imagewise removing a photosensitive layer (image-forming layer) formed on the surface of a support, and post-treatment steps such as washing of the developed printing plate with a rinsing liquid, and the treatment-of the developed printing plate with a rinsing solution containing a surface active agent or a desensitizing solution containing gum arabic and a starch derivative.
In recent years, on the other hand, the waste liquid from the development step has caused environmental problem in the printing industry because it is alkaline. Further, the plate making procedure is under rationalization. It has thus been desired to provide a printing plate precursor which does not require the foregoing complicated wet development and thus can be immediately used for printing after exposure.
Radiation-sensitive image-forming materials adapted for the production of positive-working lithographic printing plate requiring no treatment are described in JP-A-7-186562 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”). The above cited patent discloses a compound containing a functional group having a specific carboxylic acid ester structure which changes from hydrophobic to hydrophilic when acted upon by heat or acid. The use of such a compound allows printing without development after exposure, to obtain satisfactory printed matter. However, it has been desired to further improve the press life of such a lithographic printing plate.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a radiation-sensitive lithographic printing plate which can be subjected to aqueous development or does not require any special treatment such as wet development and rubbing after image writing, particularly a heat-sensitive lithographic printing plate which can be subjected to recording by a solid laser or semiconductor laser emitting infrared rays to allow direct plate making from digital data.
It is another object of the present invention to provide a heat-sensitive lithographic printing plate excellent in press life.
These and other objects of the present invention will become apparent from the following detailed description and examples.
The inventors made extensive studies of the foregoing problems. As a result, it was found that the foregoing objects of the present invention can be solved with a novel heat-sensitive lithographic printing plate comprising an image-forming layer containing a polymer which is capable of changing its hydrophilicity by heat and is one crosslinked by crosslinking reaction.
The heat-sensitive lithographic printing plate according to the present invention comprises a characteristic polymer incorporated in its image-forming layer to provide the image-forming layer with an enhanced film strength.
The heat-sensitive lithographic printing plate according to the present invention allows the foregoing polymer to undergo imagewise change in its hydrophilicity when acted upon by heat from a predetermined heating means or an acid generated by a predetermined acid generating means, allowing printing without development treatment for the formation of an image and hence making it possible to obtain a satisfactory printed matter. The heat-sensitive lithographic printing plate according to the present invention is also excellent in press life. The crosslinked polymer is preferably one crosslinked by photo-crosslinking reaction without being heated, since it is more effective for the protection of a functional group which changes in its hydrophilicity when acted upon by heat.
DETAILED DESCRIPTION OF THE INVENTION
The polymer to be incorporated in the image-forming layer of the heat-sensitive lithographic printing plate of the present invention is not specifically limited so far as it is capable of changing its hydrophilicity when acted upon by heat and is crosslinked.
The change in hydrophilicity may be from hydrophobicity to hydrophilicity or vice versa.
If the former change occurs, the heat-sensitive lithographic printing plate of the present invention is positive-working. On the contrary, if the latter change occurs, the heat-sensitive lithographic printing plate of the present invention is negative-working.
The foregoing change in the hydrophilicity of the polymer is preferably attained by allowing the polymer to have in its side chain the group which change in its hydrophilicity when acted upon by heat.
Examples of the group which changes from hydrophobic to hydrophilic when acted upon by heat will be further described with reference to at least one functional group selected from the group consisting of sulfonic acid ester group, disulfone group, sulfonimide group and alkoxyalkylester group.
Sulfonic acid ester group, disulfone group and sulfonimide group can be represented by the following general formulae (1), (2) and (3), respectively.
—L—SO
2
—O—R
1
(1)
—L—SO
2
—SO
2
—R
2
(2)
wherein L represents an organic group composed of polyvalent nonmetallic atoms required for connecting the functional group represented by the general formula (1), (2) or (3) to the polymer skeleton; and R
1
, R
2
, R
3
and R
4
each represent a substituted or unsubstituted aryl group, substituted or unsubstituted alkyl group or cyclic imide group.
The substituted or unsubstituted aryl group represented by R
1
, R
2
, R
3
or R
4
may be carbocyclic or heterocyclic. As the carbocyclic aryl group there may be used a C
6-19
carbocyclic aryl group such as phenyl group, naphthyl group, anthracenyl group and pyrenyl group. As the heterocyclic aryl group there may be used a heterocyclic aryl group having from 3 to 20 carbon atoms and from 1 to 5 heteroatoms such as pyridyl group, furyl group and other heterocyclic groups obtained by the condensation of benzene rings, e.g., quinolyl, benzofuryl, thioxanthone and carbazole. The substituted or unsubstituted alkyl group represented by R
1
, R
2
, R
3
or R
4
may be a straight-chain, branched or cyclic alkyl group having from 1 to 25 carbon atoms such as methyl group, ethyl group, isopropyl group, t-butyl group and cyclohexyl group.
Examples of the substituents on the substituted aryl, heteroaryl or alkyl group represented by R
1
, R
2
, R
3
or R
4
include C
1-10
alkoxy group such as methoxy group and ethoxy group, halogen atom such as fluorine atom, chlorine atom and bromine atom, halogen-substituted alkyl group such as trifluoromethyl group and trichloromethyl group, C
2-15
alkoxycarbonyl or aryloxycarbonyl group such as methoxycarbonyl group, ethoxycarbonyl group, t-butyloxycarbonyl group and p-chlorophenyloxycarbonyl group, hydroxyl group, acyloxy group such as acetyloxy group, benzoyloxy group and p-diphenylaminobenzoyloxy group, carbonate group such as t-butyloxycarbonyloxy group, ether group such as t-butyloxycarbonylmethyloxy group and 2-pyranyloxy group, substituted or unsubstituted amino group such as amino group, dimethylamino group, diphenylamino group, morpholino group and acetylamino group, thioether group such as methylthio group and phenylthio group, alkenyl group such as vinyl group and styryl group, nitro group, cyano group, acyl group such as formyl group, acetyl group and benzoyl grou
Baxter Janet
Burns Doane , Swecker, Mathis LLP
Gilliam Barbara
LandOfFree
Heat-sensitive lithographic printing plate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat-sensitive lithographic printing plate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat-sensitive lithographic printing plate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3054988