JP2002086947A - Original plate for heat sensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an original plate for a heat sensitive lithographic printing plate capable of printing by mounting in a printer as it is without treating after scanning exposure based on a digital signal, having excellent plate wear resistance and difficulty to stain and improving printing coating properties and a sensitivity. SOLUTION: The original plate for the heat sensitive lithographic printing plate comprises (1) an ink acceptive layer and (2) a hydrophilic layer containing a colloidal particle-like oxide or a 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 of 99 to 80 pts.wt. and a polyacrylic acid having a weight-average molecular weight of 2,000 to 50,000 of 1 to 20 pts.wt. on a support. At least one layer of the acceptive layer and the hydrophilic layer contains a photothermal conversion agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive lithographic printing plate not requiring development. More specifically, an image can be recorded by infrared laser beam scanning exposure based on a digital signal, and the recorded image can be directly mounted on a printing machine and printed without going through a conventional developing process. The present invention relates to a lithographic printing plate that is capable of being excellent in sensitivity, printing start inking property, and printing durability.

[0002]

2. Description of the Related Art Various methods have been proposed for a lithographic printing plate precursor that can be mounted on a printing machine without any processing after exposure and printing can be performed. One of the promising methods is a method using ablation in which a solid-state high-power infrared laser such as a semiconductor laser or a YAG laser is used for exposure, and the exposed portion is heated with a photothermal conversion agent that converts light into heat, thereby causing decomposition and evaporation. It is. That is, a hydrophilic layer is provided on a substrate having a lipophilic ink-receiving surface or a lipophilic ink-receiving layer, and the hydrophilic layer is ablated and removed.

[0003] WO 94/18005 discloses a printing plate in which a crosslinked hydrophilic layer is provided on a lipophilic laser light absorbing layer, and the hydrophilic layer is ablated. The hydrophilic layer is formed by cross-linking polyvinyl alcohol with a hydrolyzate of tetraethoxysilicon and containing titanium dioxide particles to improve the film strength of the hydrophilic layer. This technology improves press life. However, since it is mainly composed of polyvinyl alcohol having a hydrocarbon group and not necessarily having high hydrophilicity, the stain resistance is insufficient, and further improvement is required.

[0004] WO98 / 40212, WO99 /
JP-A-19143 and WO99 / 19144 disclose, on a substrate coated with an ink-receiving layer, a hydrophilic layer mainly composed of a colloid such as silica crosslinked with a crosslinking agent such as aminopropyltriethoxysilane. A lithographic printing plate that can be mounted on a printing press without development is disclosed. The hydrophilic layer has reduced hydrocarbon groups as much as possible to enhance the resistance to printing stains, and improves the printing durability by crosslinking the colloid with a crosslinking agent.

[0005]

However, with the above-mentioned technology, the printing durability is inadequate at several thousand sheets, and the digital direct non-processing printing plate utilizing ablation in the prior art has the difficulty of the technology of no processing. For this reason, there is a problem in that either the difficulty of smearing or the printing durability, which is the basis of printing, is impaired.

As a result of various studies, beryllium, magnesium, aluminum, silicon, titanium, beryllium, magnesium, aluminum, silicon, titanium,
A heating unit containing a colloid of an oxide or hydroxide of at least one element selected from boron, germanium, tin, zirconium, iron, vanadium, antimony, and transition metal, a hydrophilic resin, and the like, and a heating unit for fountain solution for printing. Alternatively, by providing a heat-sensitive lithographic printing plate precursor having a three-dimensionally cross-linked hydrophilic layer which is easily removed by ink and a water-soluble overcoat layer in order, the printing durability and stain resistance of the digital direct unprocessed printing plate are reduced. (See Japanese Patent Application No. 11-2476644), however, even with such a heat-sensitive lithographic printing plate, the inking property at the time of printing is insufficient, and the loss until complete inking is achieved. It was found that there was a problem with much paper and a problem with low sensitivity.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to further solve the above-mentioned new problem, and it is possible to directly mount the printing apparatus on a printing machine without performing post-exposure processing and to perform printing. An object of the present invention is to provide a heat-sensitive lithographic printing plate which is excellent in difficulty and has improved inking property and sensitivity in printing.

[0008]

The present inventors have conducted intensive studies and as a result, have found that the weight average molecular weight of 2,0
The present invention was found to achieve the above object by using polyacrylic acid of 100 to 50,000 and limiting the addition ratio of colloidal particulate oxides or hydroxides of elements such as silicon to the present invention. Was. That is, the present invention is as follows.

1. On a support, (1) an ink-receiving layer, and (2) 99 to 80 parts by weight selected from beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony and transition metals. An ink receiving layer having a hydrophilic layer containing a colloidal particulate oxide or hydroxide of at least one element to be produced, and 1 to 20 parts by weight of polyacrylic acid having a weight average molecular weight of 2,000 to 50,000. And a heat-sensitive lithographic printing plate in which at least one of the hydrophilic layers contains a photothermal conversion agent.

[0010] 2. On a support, (1) an ink receiving layer,
(2) a heat-sensitive composition comprising the hydrophilic layer described in 1 above, and (3) a water-soluble overcoat layer, wherein at least one of the ink-receiving layer, the hydrophilic layer and the water-soluble overcoat layer contains a photothermal conversion agent. Lithographic printing plate.

[0011]

Embodiments of the present invention will be described below in detail. As the support used in the present invention,
A dimensionally stable plate is used. Paper, paper laminated with lipophilic plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, nickel, stainless steel plate, etc.), plastic film (eg, cellulose diacetate, Cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate,
Polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and a paper or plastic film on which the above metal is laminated or vapor-deposited.

Preferred substrates are polyethylene terephthalate film, polycarbonate film, aluminum or steel plate, or aluminum or steel plate laminated with a lipophilic plastic film.

[0013] The aluminum plate used in the present invention is a pure aluminum plate or an alloy plate containing aluminum as a main component and containing a trace amount of a different element, and further has a plastic laminated on a thin film of aluminum or an aluminum alloy. It is. The foreign elements contained in aluminum alloys include silicon, iron, manganese, copper, magnesium,
There are chromium, zinc, bismuth, nickel, titanium and the like. The content of the foreign element in the alloy is at most 10% by weight or less. Further, an aluminum plate from an aluminum ingot using the DC casting method or an aluminum plate from an ingot using the continuous casting method may be used. However, as the aluminum plate applied to the present invention, an aluminum plate of a conventionally known and used material can be appropriately used.

The thickness of the substrate used in the present invention is 0.05 mm to 0.6 mm, preferably 0.1 mm to 0.6 mm.
0.4 mm, particularly preferably 0.15 mm to 0.3 mm
It is.

Prior to using the aluminum plate, it is preferable to perform a surface treatment such as surface roughening and anodic oxidation. The surface treatment facilitates the adhesion to the ink receiving layer.

The surface roughening treatment of the aluminum plate surface is performed by various methods. For example, a method of mechanically roughening the surface, a method of electrochemically dissolving and roughening the surface, and a method of chemically roughening the surface. It is performed by a method of selective dissolution. As a mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, and a buff polishing method can be used. As a chemical method, a method of immersing in a saturated aqueous solution of an aluminum salt of a mineral acid as described in JP-A-54-31187 is suitable. Further, as an electrochemical surface roughening method, there is a method of carrying out an alternating current or a direct current in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Also,
An electrolytic surface roughening method using a mixed acid as disclosed in JP-A-54-63902 can also be used.

The surface roughening by the above-mentioned method is carried out when the center line average roughness (Ra) of the surface of the aluminum plate is from 0.2 to 1.0.
It is preferable that the coating be performed within a range of 0 μm. The roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide or sodium hydroxide as required, and further neutralized, and then anodized to enhance abrasion resistance if desired. Processing is performed.
As an electrolyte used for anodizing the aluminum plate, various electrolytes forming a porous oxide film can be used, and generally, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of the electrolyte. The anodizing treatment conditions vary depending on the electrolyte used and cannot be specified unconditionally, but generally the concentration of the electrolyte is 1 to 80% by weight.
Solution, liquid temperature is 5 to 70 ° C, current density is 5 to 60 A / dm ² ,
A voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are appropriate. The amount of the formed oxide film is 1.0-5.
0 g / m ^2, it is particularly preferably 1.5 to 4.0 g / m ^2.

The support used in the present invention may be a substrate having the above-mentioned surface treatment and having an anodic oxide film as it is, but it is necessary to further improve the adhesion to the upper layer and the heat insulation. Accordingly, Japanese Patent Application No. 2000-65219
And anodic oxide coating described in Japanese Patent Application No. 2000-14387, enlarging the micropores, sealing the micropores, and immersing the surface in an aqueous solution containing a hydrophilic compound. Can be done. Suitable hydrophilic compounds for the above-mentioned hydrophilization treatment include polyvinyl phosphonic acid, compounds having a sulfonic acid group, saccharide compounds, citric acid, alkali metal silicates, potassium zirconium fluoride, phosphates / inorganic fluorine compounds, and the like. Can be mentioned.

The ink receiving layer of the present invention contains a lipophilic organic polymer soluble in a solvent capable of forming a film. Useful organic polymers include polyester, polyurethane, polyurea, polyimide, polysiloxane, polycarbonate, phenoxy resin, epoxy resin, phenol / formaldehyde resin, alkylphenol / formaldehyde resin, polyvinyl acetate, acrylic resin and copolymers thereof, and polyvinylphenol. , Polyvinyl halogenated phenol, methacrylic resin and its copolymer, acrylamide copolymer, methacrylamide copolymer, polyvinyl formal, polyamide, polyvinyl butyral, polystyrene, cellulose ester resin,
Examples thereof include polyvinyl chloride and polyvinylidene chloride.

Among these, as a more preferable compound, a resin having a hydroxyl group, a carboxyl group, a sulfonamide group or a trialkoxysilyl group in a side chain is excellent in adhesion to a substrate or an upper hydrophilic layer, and depending on the case. It is desirable because it is easily cured with a crosslinking agent. In addition, an acrylonitrile copolymer, a polyurethane, a copolymer having a sulfonamide group in a side chain or a copolymer having a hydroxyl group in a side chain, which is photocured with a diazo resin, is preferable.

Other phenols, cresol (m-cresol, p-cresol, m / p mixed cresol), phenol / cresol (m-cresol, p-cresol, m / p mixed cresol), phenol-modified xylene, t-butylphenol, Octylphenol, resorcinol, pyrogallol, catechol, chlorophenol (m-Cl, p-Cl), bromophenol (m-
Novolak resins and resole resins for condensation with formaldehyde such as Br, p-Br), salicylic acid and phloroglucinol, as well as condensation resins for the above phenolic compounds and acetone are useful.

Other suitable high molecular compounds include copolymers having a molecular weight of usually 10,000 to 200,000, having the following structural units as monomers (1) to (12). (1) Acrylamides, methacrylamides, acrylates, methacrylates and hydroxystyrenes having an aromatic hydroxyl group, for example, N- (4-hydroxyphenyl) acrylamide or N- (4-hydroxyphenyl) methacryl Amide, o
-, M- and p-hydroxystyrene, o-, m- and p-hydroxyphenyl acrylate or methacrylate, (2) acrylates and methacrylates having an aliphatic hydroxyl group, for example, 2-
Hydroxyethyl acrylate or 2-hydroxyethyl methacrylate,

(3) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, phenyl acrylate, benzyl acrylate, acrylic acid-2 (Substituted) acrylates such as -chloroethyl, 4-hydroxybutyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate, (4) methyl methacrylate,
Ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, 4-hydroxybutyl methacrylate, (Substituted) methacrylates such as glycidyl methacrylate and N-dimethylaminoethyl methacrylate;

(5) Acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-ethylacrylamide, N-ethylmethacrylamide, N-hexylacrylamide, N
-Hexyl methacrylamide, N-cyclohexyl acrylamide, N-cyclohexyl methacrylamide, N
-Hydroxyethylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N
-Phenylmethacrylamide, N-benzylacrylamide, N-benzylmethacrylamide, N-nitrophenylacrylamide, N-nitrophenylmethacrylamide, N-ethyl-N-phenylacrylamide and N
Acrylamide or methacrylamide such as -ethyl-N-phenylmethacrylamide,

(6) Ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether,
Vinyl ethers such as octyl vinyl ether and phenyl vinyl ether; (7) vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate; (8) styrenes such as styrene, methyl styrene and chloromethyl styrene; 9)
Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone; (10) olefins such as ethylene, propylene, isobutylene, butadiene, and isoprene; (11) N
-Vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile, etc.

(12) N- (o-aminosulfonylphenyl) acrylamide, N- (m-aminosulfonylphenyl) acrylamide, N- (p-aminosulfonylphenyl) acrylamide, N- [1- (3-aminosulfonyl) Naphthyl] acrylamide, acrylamides such as N- (2-aminosulfonylethyl) acrylamide, N- (o-aminosulfonylphenyl) methacrylamide, N- (m-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonyl) Methacrylamides such as phenyl) methacrylamide, N- [1- (3-aminosulfonyl) naphthyl] methacrylamide, N- (2-aminosulfonylethyl) methacrylamide, and o-aminosulfonylphenyl acrylate, m-amino Sulfo sulfonyl phenyl acrylate,
p-aminosulfonylphenyl acrylate, 1- (3
-Aminosulfonylphenylnaphthyl) unsaturated sulfonamides such as acrylates such as acrylate, o-aminosulfonylphenylmethacrylate, m
Unsaturated sulfonamides such as methacrylic esters such as -aminosulfonylphenyl methacrylate, p-aminosulfonylphenyl methacrylate and 1- (3-aminosulfonylphenylnaphthyl) methacrylate;

The ink receiving layer of the present invention further comprises a crosslinking agent,
An adhesion aid, a colorant, inorganic or organic fine particles, a coating surface condition improving agent, and a plasticizer can be added as necessary. In addition, the ink receiving layer may contain a light-to-heat conversion agent for increasing the sensitivity or a heat coloring or decoloring additive for forming a printed image after exposure.

Specific crosslinking agents for crosslinking organic polymers include diazo resins, aromatic azide compounds, epoxy resins, isocyanate compounds, blocked isocyanate compounds, initial hydrolyzed condensates of tetraalkoxy silicon, glyoxal, aldehyde compounds and methylol. Compounds can be mentioned.

As the adhesion aid, the above-mentioned diazo resin is excellent in adhesion to a substrate and a hydrophilic layer. In addition, a silane coupling agent, an isocyanate compound and a titanium coupling agent are also useful.

As the coloring agent, ordinary dyes and pigments are used. In particular, rhodamine 6G chloride, rhodamine B chloride, crystal violet, malachite green oxalate, oxazine 4 perchlorate, quinizarin,
2- (α-naphthyl) -5-phenyloxazole and coumarin-4. Specifically, as other dyes,
Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black B
Y, oil black BS, oil black T-505
(The above are manufactured by Orient Chemical Industry Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI4255)
5), methyl violet (CI42535), ethyl violet, methylene blue (CI52015), patent pure blue (manufactured by Sumitomo Sangoku Chemical Co., Ltd.), brilliant blue, methyl green, erythricin B, basic fuchsin, m-cresol purple, auramine, 4
Triphenylmethane-based, diphenylmethane-based, oxazine-based, xanthene-based, iminonaphthoquinone-based, azomethine-based or anthraquinone-based dyes such as -p-diethylaminophenyliminaphthoquinone and cyano-p-diethylaminophenylacetanilide; -293247, Japanese Patent Application No. 7-3351.
No. 45 can be mentioned. When the dye is added to the ink receiving layer, it is usually about 0.02 to 10% by weight based on the total solid content of the receiving layer.
More preferably, the proportion is from about 0.1 to 5% by weight.

Further, fluorine-based surfactants and silicon-based surfactants which are well-known compounds as coating surface condition improvers can also be used. Specifically, a surfactant having a perfluoroalkyl group or a dimethylsiloxane group is useful for preparing the coated surface.

The inorganic or organic fine particles which can be used in the present invention include colloidal silica and colloidal aluminum having a diameter of from 10 nm to 100 nm, and inert particles having a particle diameter larger than these colloids, for example, silica particles, surface-hydrophobicized particles. Silica particles, alumina particles, titanium dioxide particles, other heavy metal particles, clay and talc. The addition of these inorganic or organic fine particles to the ink receiving layer has the effect of improving the adhesion to the upper hydrophilic layer and increasing the printing durability in printing. The addition ratio of these fine particles in the ink receiving layer is 80% by weight or less of the total amount, preferably 40% by weight or less.

Further, a plasticizer may be added to the ink receiving layer of the present invention, if necessary, in order to impart flexibility to the coating film. For example, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, oligomers of acrylic acid or methacrylic acid And polymers.

Further, it is preferable to add a coloring or decoloring compound to the ink receiving layer of the present invention in order to sharpen the image area and the non-image area when exposed. For example,
Leuco dyes (leucomalachite green, leucomalachite green, etc.) along with thermal acid generators such as diazo compounds and diphenyliodonium salts
Leuco crystal violet, lactone of crystal violet, etc.) and PH discoloration dye (eg, dye such as ethyl violet, Victoria Poor Blue BOH)
Is used. In addition, a combination of an acid coloring dye and an acidic binder as described in EP 897134 is also effective. In this case, the bond in the associated state forming the dye is broken by heating, and a lactone is formed to change from colored to colorless. The addition ratio of these coloring or decoloring systems is 10% by weight based on the total solids in the receiving layer.
It is preferably at most 5% by weight.

As a solvent for coating the ink receiving layer, alcohols (methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol,
Propylene glycol, dipropylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc.), ethers (tetrahydrofuran, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, tetrahydropyran, etc.), ketones (acetone, methyl ethyl ketone, Acetylacetone, etc.), esters (methyl acetate, ethylene glycol monomethyl monoacetate, methyl lactate, ethyl lactate,
Gamma-butyrolactone), amides (formamide, N-methylformamide, pyrrolidone, N-methylpyrrolidone, etc.) and the like can be used. These solvents are used alone or in a mixed state. When preparing a coating solution, the concentration of the components of the ink receiving layer (total solids including additives) in the solvent is preferably 1 to 50% by weight. In addition, a film can be formed not only from the above-mentioned application from an organic solvent but also from an aqueous emulsion. In this case, the concentration is preferably 5% by weight to 50% by weight.

The thickness of the ink receiving layer in the present invention after coating and drying is not particularly limited. However, when it is provided on a metal plate, it has a role as a heat insulating layer. It is more preferably at least 0.2 μm. When a lipophilic plastic film is used as the substrate, the ink receiving layer only needs to be able to function as an adhesive layer with the upper layer. It is preferably at least 05 μm.

The hydrophilic layer used in the present invention is a layer which is insoluble in a fountain solution by lithographic printing using a fountain solution and ink, and is a layer of beryllium, magnesium, aluminum, silicon,
Titanium, boron, germanium, tin, zirconium,
It is formed by applying a solution containing colloidal particulate oxide or hydroxide of at least one element selected from iron, vanadium, antimony and transition metal, and polyacrylic acid. Aluminum, silicon, titanium and zirconium are particularly preferred among the elements constituting the colloidal particulate oxide or hydroxide used in the present invention.

The size of the colloid used in the present invention is as follows.
Spherical silica having a particle size of 5 to 100 nm is preferable. Spherical particles having a particle size of 10 to 50 nm are 50 to 400 nm
Can be used. Feathers such as 100 nm × 10 nm like aluminum oxide or hydroxide colloids are also effective.

These colloids can be prepared by various known methods such as hydrolysis of halides or alkoxy compounds of the above elements or condensation of hydroxides. For example,
A sol can also be prepared by applying a hydrolysis / condensation reaction directly from di, tri and / or tetraalkoxysilane under an acid catalyst to apply. When this sol is applied, a stronger hydrophilic three-dimensional crosslinked film can be obtained. In addition, a commercially available product such as Nissan Chemical Industries, Ltd. may be selected and used as the colloid dispersion liquid.

The polyacrylic acid used in the hydrophilic layer of the present invention has a weight average molecular weight of 2,000 to 50,000. If the molecular weight is larger than this range, on-press developability will be reduced, resulting in lower sensitivity and reduced printing durability. The decrease in printing durability is presumed to be due to deterioration in compatibility with colloid particles such as silica. If the molecular weight is smaller than this range, the printing durability will decrease.

The amount of polyacrylic acid added to the hydrophilic layer depends on the amount of the colloidal particulate oxide or hydroxide added.
It is 1 to 20 parts by weight with respect to 0 parts by weight. With such a ratio, good printing durability, difficulty in staining, sensitivity, and printable inking property can be obtained. If the addition amount of polyacrylic acid is more than this range, the sensitivity is lowered and the inking property of printing is lowered. If it is less than this range, the sensitivity and the printing durability deteriorate.

The hydrophilic layer of the present invention may contain, in addition to the above-mentioned colloid and polyacrylic acid, a crosslinking agent for accelerating the crosslinking of the colloid. As such a colloid crosslinking agent, an initial hydrolysis condensate of tetraalkoxysilane, trialkoxysilylpropyl-N, N, N-trialkylammonium halide or aminopropyltrialkoxysilane is preferable. It is preferable that the addition ratio is 5% by weight or less of the total solid content of the hydrophilic layer.

The hydrophilic layer containing each component described above is provided by preparing a solution in which each component is dissolved or dispersed in a solvent, and applying the solution. As the main solvent of the hydrophilic layer coating solution, water and low-boiling alcohols such as methanol, ethanol and propanol are used alone or as a mixture.

The hydrophilic layer of the present invention may further include a well-known fluorine-based surfactant for improving the surface condition of the coating.
A silicon-based surfactant, a polyoxyethylene-based surfactant, or the like may be added.

The coating thickness of the hydrophilic layer of the present invention is preferably from 0.1 μm to 3 μm. Within this range, ablation is good and printing durability is good.

In the heat-sensitive lithographic printing plate of the present invention, an overcoat layer containing a water-soluble resin as a main component is provided on the hydrophilic layer in order to suppress scattering of scum due to ablation and to prevent contamination of the hydrophilic layer by a lipophilic substance. be able to.

The water-soluble overcoat layer used in the present invention can be easily removed at the time of printing and contains a resin selected from water-soluble organic polymer compounds. As the water-soluble organic polymer compound used here, a film formed by coating and drying has a film-forming ability, specifically, polyvinyl acetate (having a hydrolysis rate of 65% or more), polyacrylic Acid, alkali metal salt or amine salt thereof, polyacrylic acid copolymer, alkali metal salt or amine salt thereof, polymethacrylic acid, alkali metal salt or amine salt thereof, polymethacrylic acid copolymer, alkali metal salt thereof or amine Salt, polyacrylamide, its copolymer, polyhydroxyethyl acrylate, polyvinylpyrrolidone, its copolymer, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamide-2-methyl-
1-propanesulfonic acid, an alkali metal salt or an amine salt thereof, poly-2-acrylamido-2-methyl-1
-Propanesulfonic acid copolymer, alkali metal salt or amine salt thereof, gum arabic, cellulose derivative (for example, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.), a modified product thereof, white dextrin, pullulan, enzymatically decomposed ether Dextrin and the like. Further, according to the purpose, two or more of these resins can be used in combination.

In addition, a nonionic surfactant can be mainly added to the overcoat layer in the case of aqueous solution application in order to ensure uniformity of application. Specific examples of such a nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan triolate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecyl ether, and the like. . The proportion of the nonionic surfactant in the total solid content of the overcoat layer is preferably 0.05 to 5% by weight, and more preferably 1 to 3% by weight.

The thickness of the overcoat layer used in the present invention is preferably from 0.05 μm to 4.0 μm, and more preferably from 0.1 μm to 1.0 μm. Within this range, good suppression of scattering of ablation scum and prevention of contamination of the hydrophilic layer can be obtained without impairing the dissolution and removal properties of the overcoat layer by the dampening solution during printing.

In the present invention, a photothermal conversion agent having a function of absorbing infrared rays and generating heat is added to at least one of the ink receiving layer, the hydrophilic layer and the overcoat layer in order to increase the sensitivity to infrared rays. .

The photothermal conversion agent may be any substance that absorbs light of 700 nm or more, and various pigments and dyes can be used. Examples of pigments include commercially available pigment and color index (CI) handbook, “Latest Pigment Handbook” (edited by The Japan Pigment Technical Association, 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “printing”. Pigments described in "Ink Technology" (CMC Publishing, 1984) can be used.

Examples of the type of the pigment include a black pigment, a brown pigment, a red pigment, a violet pigment, a blue pigment, a green pigment, a fluorescent pigment, a metal powder pigment, and a polymer-bound pigment. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelated azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments And quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like.

These pigments may be used without surface treatment, or may be used after surface treatment. The method of surface treatment is a method of surface coating a hydrophilic resin or lipophilic resin,
A method of attaching a surfactant, a method of bonding a reactive substance (for example, silica sol, alumina sol, a silane coupling agent, an epoxy compound, an isocyanate compound, and the like) to the surface of the pigment are considered. The above surface treatment method,
It is described in "Properties and Applications of Metallic Soaps" (Koshobo), "Printing Ink Technology" (CMC Publishing, 1984) and "Latest Pigment Application Technology" (CMC Publishing, 1986). Among these pigments, those that absorb infrared rays are preferred because they are suitable for use in lasers that emit infrared rays. As such a pigment that absorbs infrared rays, carbon black is particularly preferred.

As the pigment to be added to the hydrophilic layer and the overcoat layer of the present invention, the surface is preferably coated with a hydrophilic resin or silica sol so as to be easily dispersed in a water-soluble or hydrophilic resin and not to impair the hydrophilicity. Carbon black is useful.

The particle size of the pigment is preferably in the range of 0.01 μm to 1 μm, and more preferably in the range of 0.01 μm to 0.5 μm. As a method for dispersing the pigment, a known dispersion technique used in the production of ink or toner can be used. As the disperser, an ultrasonic disperser,
Sand mills, attritors, pearl mills, super mills, ball mills, impellers, dispersers, KD mills, colloid mills, dynatrons, three-roll mills, pressure kneaders and the like can be mentioned. Details are described in “Latest Pigment Application Technology” (CMC Publishing, 1986).

As the dye, commercially available dyes and literatures (for example, "Dye Handbook" edited by The Society of Synthetic Organic Chemistry, published in 1970,
"Chemical Industry", May 1986, p. 45-51 "Near-infrared absorbing dyes", "Development and market trends of functional dyes in the 1990s", Chapter 2, Section 2.3 (1990), or known dyes described in patents can be used. . Specifically, infrared absorbing dyes such as azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, polymethine dyes, and cyanine dyes are preferred.

Further, examples of the infrared absorbing dye include, for example, JP-A-58-125246 and JP-A-59-84356.
Cyanine dyes described in JP-A-60-78787, JP-A-58-173696, JP-A-58-173696
181690, methine dyes described in JP-A-58-194595 and the like, JP-A-58-112793,
JP-A-58-224793, JP-A-59-48187
JP-A-59-73996, JP-A-60-5294
No. 0, naphthoquinone dyes described in JP-A-60-63744 and the like, squalilium dyes described in JP-A-58-112792 and the like, British Patent 434,8
No. 75, and US Pat. No. 4,756,9.
No. 93, a cyanine dye described in U.S. Pat. No. 4,973,572, a dye described in JP-A-10-268512, and a phthalocyanine compound described in JP-A-11-235883.

As a dye, US Pat. No. 5,156,
No. 938 is also preferably used, and substituted arylbenzo (thio) pyrylium salts described in U.S. Pat. No. 3,881,924;
No. 42645 (US Pat. No. 4,327,169)
Described in JP-A-58-18.
No. 1051, No. 58-220143, No. 59-413
No. 63, No. 59-84248, No. 59-84249
Pyrylium compounds described in JP-A-59-146063 and JP-A-59-146061;
Cyanine dyes described in U.S. Pat. No. 2,216,146, pentamethine thiopyrylium salts described in U.S. Pat. No. 4,283,475, and Japanese Patent Publication Nos. 5-135514 and 5-19702.
Nos. 4,059,098, 4,098,098, 4,098,097, and 3,087,098. Also preferred are pyrylium compounds described in Japanese Patent Application Publication No. JP-A-2002-209, Epolite III-178, Epolite III-130, Epolite III-125 and the like. Among these, a particularly preferred dye to be added to the overcoat layer and the hydrophilic layer is a water-soluble dye, and specific examples are listed below by structural formulas.

[0059]

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[0060]

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The dye used in the ink receiving layer of the present invention may be the above-mentioned infrared absorbing dye, but is preferably a more lipophilic dye. More preferred dyes include the dyes exemplified below.

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[0063]

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The addition ratio of the photothermal conversion agent is 1 to 50% by weight, preferably 2 to 20% by weight of the solid content in the hydrophilic layer. In the overcoat layer, 1 to 70% by weight of solids,
Preferably 2 to 50% by weight, when the photothermal conversion agent is a dye,
The proportion is particularly preferably 2 to 30% by weight, and when the photothermal conversion agent is a pigment, the proportion is particularly preferably 20 to 50% by weight. The addition ratio of the photothermal conversion agent to the ink receiving layer is preferably 20% by weight or less of the total solids of the ink receiving layer, and particularly preferably 15% by weight or less. Within these ranges, good sensitivity can be obtained without impairing the film strength of each layer.

The heat-sensitive lithographic printing plate of the present invention forms an image by heat. Specifically, direct image-like recording using a thermal recording head or the like, scanning exposure using an infrared laser, high-intensity flash exposure such as a xenon discharge lamp, or infrared lamp exposure is used. Semiconductors that emit infrared light having a wavelength of 700 to 1200 nm are used. Exposure with a solid-state high-output infrared laser such as a laser or a YAG laser is preferable. The image-exposed printing plate of the present invention can be mounted on a printing press without further processing. Alternatively, it is also possible to attach a printing original plate to a printing press, perform laser exposure on the printing press, and then perform printing as it is. When printing is started using the ink and fountain solution, the overcoat layer and the hydrophilic layer in the exposed area are removed by the fountain solution, and the ink is deposited on the ink receiving layer below it. Can be

[0066]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 [Production of aluminum substrate] 99.5 weight of aluminum
%, 0.01% by weight of copper, 0.03% by weight of titanium,
JI containing 0.3% by weight of iron and 0.1% by weight of silicon
SA1050 rolled 0.24mm aluminum plate
Of a 400 mesh pamistone (manufactured by Kyoritsu Ceramics)
Weight percent aqueous suspension using a rotating nylon brush
After graining the surface, it was thoroughly washed with water. This is 15
Wt% sodium hydroxide aqueous solution (aluminum 4.5
% Of aluminum) and the dissolution amount of aluminum is 5 g / m^Two
And then washed with running water. Change
Neutralized with a 1% by weight aqueous nitric acid solution, then 0.7% by weight nitric acid
Anode in acid aqueous solution (containing 0.5% by weight of aluminum)
Square wave alternating wave with hour voltage 10.5V, cathode hour voltage 9.3V
Voltage (current ratio r = 0.90, Japanese Patent Publication No. 58-5796)
160 using the current waveform described in the publication example)
C / dm^TwoThe electrolytic surface roughening treatment was performed with the amount of electricity at the time of anode.
After washing with water, in a 10% by weight aqueous sodium hydroxide solution at 35 ° C
Immersion in aluminum, the amount of aluminum dissolved is 1 g / m ^TwoWill be
After the etching, the substrate was washed with water. Next, at 50 ° C., 30
Immersed in an aqueous solution of sulfuric acid by weight and desmutted.
I washed. Furthermore, a 20% by weight aqueous solution of sulfuric acid at 35 ° C. (Al
0.8% by weight) and using direct current
A porous anodic oxide film forming treatment was performed. That is, current density
Degree 13A / dm^TwoAnd adjust the electrolysis time
Anodic oxide film weight 2.7 g / m^TwoMake a support
Was. After washing the support with water, 70 ° C. sodium silicate
It was immersed in a 0.2% by weight aqueous solution, washed with water and dried. Adhesion
The amount is 5 mg / m as Si^TwoMet. As above
The obtained support was measured with a Macbeth RD920 reflection densitometer.
The measured reflection density is 0.30 and the center line average roughness Ra is
It was 0.58 μm.

[Coating of ink receiving layer]
An ink receiving layer coating solution having the following composition was applied to a coating solution amount of 11.2.
Coating was performed with a bar coater so as to be 5 ml / m ² . Then, it is dried by heating at 100 ° C. for 1 minute, and the dried coating amount is about 0.1%.
An ink receiving layer of 45 g / m ² was obtained.

(Coating solution of ink receiving layer) Epicoat 1100L (manufactured by Yuka Shell Epoxy) 0.8 g Epicoat 1001 (manufactured by Yuka Shell Epoxy) 0.2 g Photothermal conversion agent (IR described in this specification) -24) 0.2 g Methyl ethyl ketone 13 g Propylene glycol monomethyl ether 12 g

[Coating of Hydrophilic Layer] On the ink receiving layer thus provided, the following hydrophilic layer coating solution (I) was coated with a bar, dried at 100 ° C. for 1 minute, and dried at a dry coating amount of 0.1 μm. 39
g / m ² of the hydrophilic layer was obtained.

(Hydrophilic layer coating liquid (I)) Methanol silica (manufactured by Nissan Chemical Industries, Ltd .: colloid composed of a methanol solution containing 30% by weight of silica having a particle size of 10 to 20 nm) 50,000) 5% by weight methanol solution 2 g Methyl lactate 1 g Methanol 17.53 g

On the hydrophilic layer, an overcoat layer coating solution having the following composition was coated with a bar and dried at 100 ° C. for 90 seconds to obtain a heat-sensitive lithographic printing plate having an overcoat layer having a dry coating weight of 0.22 g / m ^2. An original plate was prepared.

(Coating solution for overcoat layer) Aqueous solution containing 28% by weight of gum arabic 1.5g Photothermal conversion agent (Dye IR-10 described in this specification) 0.042g Polyoxyethylene nonylphenyl ether (10% by weight in aqueous solution) ) 0.168g ion exchange water 22g

The above heat-sensitive lithographic printing plate was cut for 200 m using a Trendsetter (a plate setter equipped with a 40 W 830 nm semiconductor laser) manufactured by Creo.
Exposure was performed with an energy of J / cm ² . The exposed original plate was attached to Komori Corporation's Lithrone printing machine without further processing, and the plate etch solution EU was used.
-3 (manufactured by Fuji Photo Film Co., Ltd.) / Water / isopropyl alcohol (volume ratio 1/99/10) and a dampening solution using Geos G black ink manufactured by Dainippon Ink and Chemicals, Inc. When water and ink were operated at the same time and art-coated paper was supplied and printing was started, the ink was completely deposited on the fifth printout, and 20,000 good prints without stains were obtained thereafter. .

Examples 2-3 In place of the polyacrylic acid having a weight average molecular weight of 25,000 in Example 1, polyacrylic acid having a weight average molecular weight of 40,000 in Example 2 and 4,000 in Example 3 A heat-sensitive planographic printing plate was prepared in the same manner as in Example 1 except that an acid was used. Next, these heat-sensitive lithographic printing original plates were exposed and printed in the same manner as in Example 1. As a result, no more than 5 sheets of the original printing plates were printed. In addition, 20,000 good prints free of stains were obtained from both printing plates.

Example 4 The following hydrophilic layer coating solution (II) was coated on the ink receiving layer of Example 1 with a bar, dried at 100 ° C. for 1 minute, and dried at a coating amount of 0.39 g / m ² . A heat-sensitive lithographic printing plate having a hydrophilic layer and no overcoat layer was obtained.

(Hydrophilic Layer Coating Solution (II)) Methanol silica (same as in Example 1) 3 g Methanol solution containing 5% by weight of polyacrylic acid (weight average molecular weight: 25,000) 2 g Photothermal conversion agent (this specification) IR-10) 0.1 g Methyl lactate 1 g Methanol 17.53 g

This heat-sensitive lithographic printing plate was exposed using the same plate setter as in Example 1 and printed under the same printing conditions. As a result, the optimal exposure amount was 200 mJ / cm ²
Thus, the number of printed sheets was 5 and the number of printings was 20,000.

Comparative Example 1 A comparative layer was prepared in the same manner as in Example 1 except that the hydrophilic layer coating liquid (i) containing no polyacrylic acid was used in place of the hydrophilic layer coating liquid of Example 1. A heat-sensitive lithographic printing plate was prepared. The dry coating amount of the hydrophilic layer was 0.39 g / m ² .

(Comparative hydrophilic layer coating solution (i)) Methanol silica (same as in Example 1) 3.33 g Methyl lactate 1 g Methanol 19.2 g

This comparative heat-sensitive lithographic printing plate was prepared
Exposure using the same platesetter as in Example 1 and same printing
Printed under conditions. As a result, the optimal exposure amount was 240 mJ /
cm ^TwoSo, the number of inked prints is 20, and the number of prints is 20,000.
It was a sheet.

Comparative Example 2 A comparative layer was prepared in the same manner as in Example 1 except that the hydrophilic layer coating liquid (ii) containing a high molecular weight polyacrylic acid having the following composition was used instead of the hydrophilic layer coating liquid of Example 1. Of a heat-sensitive lithographic printing plate was prepared. The dry coating amount of the hydrophilic layer is 0.39 g /
m ² .

(Comparative hydrophilic layer coating solution (ii)) Methanol silica (same as in Example 1) 3 g Methanol solution containing 5% by weight of polyacrylic acid (weight average molecular weight 250,000) 2 g Methyl lactate 1 g Methanol 17.53 g

This comparative heat-sensitive lithographic printing plate was prepared
Exposure using the same platesetter as in Example 1 and same printing
Printed under conditions. As a result, the optimal exposure amount was 200 mJ /
cm ^TwoThus, the number of printed sheets is 20, and the number of printings is 1.
It was 20,000 sheets.

Comparative Example 3 A comparative layer was prepared in the same manner as in Example 1 except that the hydrophilic layer coating liquid (iii) having a high addition ratio of polyacrylic acid having the following composition was used instead of the hydrophilic layer coating liquid of Example 1. Of a heat-sensitive lithographic printing plate was prepared. The dry coating amount of the hydrophilic layer is 0.39 g /
m ² .

(Comparative hydrophilic layer coating solution (iii)) Methanol silica (same as in Example 1) 2.33 g Methanol solution containing 5% by weight of polyacrylic acid (weight average molecular weight: 25,000) 6 g Methyl lactate 1 g 15.86 g of methanol

The heat-sensitive lithographic printing plate for comparison was prepared
Exposure using the same platesetter as in Example 1 and same printing
Printed under conditions. As a result, the optimal exposure amount was 240 mJ /
cm ^TwoThe number of inked prints is 5, and the number of printings is 200.
It was 0 sheets.

Comparative Example 4 A hydrophilic layer coating solution containing a hydrophilic resin other than polyacrylic acid having the following composition in place of the hydrophilic layer coating solution of Example 1 (iv)
A heat-sensitive lithographic printing original plate for comparison was prepared in the same manner as in Example 1 except for using. The dry coating amount of the hydrophilic layer is 0.
It was 39 g / m ² .

(Comparative Coating Solution for Hydrophilic Layer (iv)) Methanol silica (same as in Example 1) 3 g Methanol solution containing 5% by weight of poly 2-hydroxyethyl methacrylate (weight average molecular weight 300,000) 2 g Methyl lactate 1 g Methanol 17.53g

This comparative heat-sensitive lithographic printing plate was prepared
Exposure using the same platesetter as in Example 1 and same printing
Printed under conditions. As a result, the optimal exposure amount was 260 mJ /
cm ^TwoThus, the number of inked prints is 40, and the number of prints is 2.
The number was 50,000.

[0091]

According to the present invention, it is possible to print by directly mounting on a printing machine without performing post-exposure processing.
It is possible to provide a heat-sensitive lithographic printing original plate which is excellent in printing durability and resistance to contamination and has improved inking property and sensitivity of printing.

Continued on the front page F term (reference) 2H025 AA01 AA12 AB03 AC08 AD03 BH02 CB43 CB55 CC08 CC11 CC20 DA02 DA36 DA40 2H096 AA06 BA09 CA20 EA04 EA23 2H114 AA04 AA22 AA24 AA27 BA01 DA04 DA15 DA25 DA26 DA03 DA03 GA06 GA08 GA09 GA34 GA38

Claims (2)

[Claims] 1. An ink receiving layer on a support, and (2) 99 to 80 parts by weight of beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium and antimony. And a hydrophilic layer containing 1 to 20 parts by weight of polyacrylic acid having a weight average molecular weight of 2,000 to 50,000, and a colloidal particulate oxide or hydroxide of at least one element selected from the group consisting of: A heat-sensitive lithographic printing plate wherein at least one of the ink-receiving layer and the hydrophilic layer contains a photothermal conversion agent; 2. On a support, (1) an ink receiving layer,
(2) a heat-sensitive composition comprising the hydrophilic layer according to claim 1, and (3) a water-soluble overcoat layer, wherein at least one of the ink-receiving layer, the hydrophilic layer and the water-soluble overcoat layer contains a photothermal conversion agent. Original plate for lithographic printing.