Heat-sensitive lithographic printing plate precursor

Details Heat-sensitive lithographic printing plate precursor Heat-sensitive lithographic printing plate precursor

2001-03-06

2003-07-15

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

C430S271100, C430S272100, C430S273100, C430S280100, C101S453000, C101S454000, C101S455000, C101S456000, C101S457000

Reexamination Certificate

active

06593057

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a heat-sensitive lithographic printing plate precursor which can dispense with development. More specifically, the present invention relates to a lithographic printing plate precursor which can record an image by the exposure of scanning an infrared ray laser beam based on digital signals, which can be mounted on a printing press as it is after the image recording and used for printing without passing through a development process as in conventional techniques, and which is improved in the impression capacity.
BACKGROUND OF THE INVENTION
Various methods have been proposed for the lithographic printing plate precursor which can be mounted on a printing press as it is after the exposure without passing through any processing and used for printing. One promising method is a method of exposing an printing plate precursor with a solid high output infrared ray laser such as semiconductor laser and YAG laser, generating heat on the exposed area by a compound capable of converting light into heat which converts light into heat, and causing decomposition and evaporation using ablation.
That is, this is a method of providing a water-receptive layer on a substrate having a lipophilic ink-receptive surface or a lipophilic ink-receptive layer, and removing the water-receptive layer by ablation.
WO98/40212 and WO99/19143 disclose a lithographic printing plate precursor capable of being mounted on a printing press without passing through development, where an ink-receptive layer and a water-receptive layer mainly comprising a colloid such as silica crosslinked by a crosslinking agent such as aminopropyltriethoxysilane are provided on a substrate. This ink-receptive layer may contain, as a binder polymer, polycarbonate, polyester, polyvinyl butyral, polyacrylate or a chemically modified cellulose derivative in addition to a compound capable of converting light into heat, and the water-receptive layer is improved in the impression capacity by crosslinking the colloid using a crosslinking agent.
WO99/19144 discloses a lithographic printing plate precursor where a heat-insulating layer containing no compound capable of converting light into heat is provided, in place of the above-described ink-receptive layer and it is stated that cellulose acetate, polymethyl methacrylate, polystyrene, polyvinyl butyral or a polycarbonate is used for the heat-insulating layer.
However, according to these techniques, the impression capacity is as low as thousands of sheets.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to solve the above-described problems and provide a heat-sensitive lithographic printing plate precursor comprising a metal support, which can be mounted directly on a printing press after the exposure without passing through any processing and used for printing and which is improved in the impression capacity.
As a result of extensive investigations to solve those problems, the present inventors have found that the above-described objects can be attained by incorporating an epoxy resin having a softening point of 120° C. or more into the ink-receptive layer.
That is, the present invention is as follows.
1. A heat-sensitive lithographic printing plate precursor comprising a metal substrate having thereon 1) an ink-receptive layer and 2) a water-receptive layer comprising a colloidal particulate oxide or hydroxide of at least one element selected from the group consisting of beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony and transition metals, at least one layer of the ink-receptive layer and the water-receptive layer containing a compound capable of converting light into heat and the ink-receptive layer containing an epoxy resin having a softening point of 120° C. or more (by Durance s mercury method).
2. The heat-sensitive lithographic printing plate precursor comprising a metal substrate having thereon 1) an ink-receptive layer and 2) the water-receptive layer as described in the above item 1, wherein 3) a water-soluble overcoat layer is further provided over the metal substrate; at least one layer of the ink-receptive layer, the water-receptive layer and the water-soluble overcoat layer contains a compound capable of converting light into heat and the ink-receptive layer contains an epoxy resin having a softening point of 120° C. or more.
DETAILED DESCRIPTION OF THE INVENTION
The ink-receptive layer of the present invention contains an epoxy resin having a softening point of 120° C. or more. Suitable examples of the epoxy resin include polyaddition products having a softening point of 120° C. or more, preferably 140° C. or more, such as bisphenol A/epichlorohydrin polyaddition product, bisphenol F/epichlorohydrin polyaddition product, halogenated bisphenol A/epichlorohydrin polyaddition product, biphenyl-type bisphenol/epichiorohydrin polyaddition product and novolak resin/epichiorohydrin polyaddition product. Specific examples thereof include EPIKOTE 1007 (softening point: 128° C., Mn: about 2,900, epoxy equivalent: 2,000), EPIKOTE 1009 (softening point: 144° C., Mn: about 3,750, epoxy equivalent: 3,000), EPIKOTE 1010 (softening point: 169° C., Mn: about 5,500, epoxy equivalent: 4,000), EPIKOTE 1100L (softening point: 149° C., epoxy equivalent: 4,000) and EPIKOTE YX31575 (softening point: 130° C., epoxy equivalent: 1,200), all produced by Yuka Shell Epoxy Co., Ltd.
The epoxy resin is dissolved in an appropriate solvent, coated on a substrate and dried to provide an ink-receptive layer on the substrate. Only the epoxy resin may be used by dissolving it in a solvent, however, if desired, a coloring agent, an inorganic or organic fine particle, a coating surface (state) improver, a plasticizer and an adhesive aid may be added.
In addition, a thermal coloration- or decolorization-type additive may also be added for forming a print-out image after the exposure.
The coloring agent is an ordinary dye or pigment and examples thereof include Rhodamine 6G chloride, Rhodamine B chloride, Crystal Violet, Malachite Green Oxalate, Oxazine 4 Perchlorate, quinizarin, 2-(&agr;-naphthyl)-5-phenyloxazole and coumarin-4. Specific examples of other dyes include triphenyl methane-, diphenyl methane-, oxazine-, xanthene-, iminonaphthoquinone-, azomethine- or anthraquinone-based dyes represented by Oil Yellow #101, Oil Yellow #103, Oil Pink #312, Oil Green BG, Oil Blue BOS, Oil Blue #603, Oil Black BY, Oil Black BS, Oil Black T-505 (all produced by Orient Kagaku Kogyo K.K.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Methylene Blue (CI52015), Patent Pure Blue (all produced by Sumitomo Mikuni Kagaku), Brilliant Blue, Methyl Green, Erythrisine B, Basic Fuchsine, m-Cresol Purple, Auramine, 4-p-diethylaminophenyliminonaphthoquinone and cyano-p-diethylaminophenylacetanilide, and dyes described in JP-A-62-293247 (the term “JP-A” used herein means an “unexamined published Japanese patent application”) and JP-A-9-179290.
The dye is usually added, when added into the ink-receptive layer, in a ratio of about 0.02 to 10% by weight, preferably from about 0.1 to 5% by weight, based on the entire solid content of the receptive layer.
In addition, a fluorine-containing surfactant or a silicon-containing surfactant, which are a compound well-known as a coating surface (state) improver, may also be used. More specifically, a surfactant having a perfluoroalkyl group or a dimethylsiloxane group is useful for conditioning the coating surface state.
Examples of the inorganic or organic fine powder which can be used in the present invention include colloidal silica and colloidal aluminum, having a particle size of 10 to 100 nm; inactive particles having a particle size larger than those colloids, such as silica particle, surface hydrophobitized silica particle, alumina particle and titanium dioxide particle; other heavy metal particles; clay; and talc. By adding this inorganic or organic fine powder into the ink-receptive layer, an e

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