JPH11334239A - Direct photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a sensitivity, an image reproducibility and ink coating properties of a printing element part by incorporating titanium oxide fine particles and/or zinc oxide fine particles in a hydrophilic layer, thereby enhanc ing removability of the layer by ablation. SOLUTION: In the case of covering a surface with a water thin film of a dampening water to be supplied at the time of printing to bring it into contact with an ink of an emulsion state, an adherence of lipophilic ink particles is prevented, and a titanium oxide and/or a zinc oxide is contained in the hydrophilic layer for forming a non-image part on a printed matter to develop good hydrophilic property. As the titanium oxide, an anatase type for facilitating its atomization is better as the oxide. As the zinc oxide, a hexagonal system is better. It is best about 50 to 80 wt.% with respect to total solid content in the hydrophilic layer as a blending ratio of the titanium oxide and/or zinc oxide. As an immobilizing method of the titanium oxide or the zinc oxide in the hydrophilic layer, there is a method for blending a wet curable or ultraviolet curable type immobilizing agent at the time of coating with the layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct photosensitive lithographic printing plate. More specifically, the present invention relates to a direct photosensitive lithographic printing plate comprising fine particles of titanium oxide and / or fine particles of zinc oxide in a hydrophilic layer. The direct-sensitive lithographic printing plate of the present invention can directly form a lithographic printing plate from a digital image data using a semiconductor laser or a light source capable of high-density light exposure according to the same, and has sensitivity and image reproducibility. High, excellent in ink deposit stain on non-image areas.

[0002]

2. Description of the Related Art In recent years, with the progress of digital image processing technology using near-infrared semiconductor lasers and computers,
Scanning exposure with a near-infrared semiconductor laser directly on a photosensitive lithographic printing plate without using a silver halide film for a printing plate from digital image data formed on a computer,
After insolubilizing the exposed portion, an image is formed by an aqueous solution developing process (wet developing process) and plate making is performed, or an image is formed by forming an image by deteriorating or sublimating, melting and removing the exposed portion (dry developing process), Laser direct plate making technology is attracting attention.

[0003] Various attempts have been made for direct photosensitive lithographic printing plates used in the digital printing system. For example, (a) a photosensitive layer and a hydrophilic layer are coated on a support in this order. In which the hydrophilic layer is simultaneously melted and removed by volatilization or combustion in response to heat generated by ablation of the exposed portion of the photosensitive layer (JP-A-7-314934, JP-A-55-105560). Each publication), (b) a transfer sheet in which a photosensitive layer is coated on a transparent support is superimposed on a printing plate substrate that has been subjected to a hydrophilic treatment so that the photosensitive layer and the hydrophilic surface are matched. Laser transfer from the upper side of the support of the transfer sheet and transfer to the substrate surface by ablation of the photosensitive layer in the exposed portion (Japanese Patent Laid-Open No. 50-102402); (c) hydrophilicity by laser irradiation Such as those for hydrophobizing the photosensitive layer (JP-A-7-1850) are known. Among these methods, the method (a) is considered to be more preferable because the image forming process is the simplest and the one excellent in normal image quality is easily obtained.

[0004]

However, in the laser direct photosensitive lithographic printing plate utilizing the ablation of the above method (a), it has conventionally been difficult to achieve both the strength and the removability of the hydrophilic layer. Was. That is,
When the strength of the hydrophilic layer is increased for the purpose of ensuring printing durability, the removability is reduced, and accordingly, the sensitivity, image reproducibility, and ink depositability of the image area tend to be reduced, which is a problem.

An object of the present invention is to provide a direct photosensitive lithographic printing plate having high sensitivity, high image reproducibility, and excellent ink receptivity in an image area by enhancing the removability of a hydrophilic layer by ablation. It is assumed that. Another object of the present invention is to provide a direct print excellent in printing durability such as printing durability and sensitivity, image reproducibility and ink receptivity by providing both the strength and the removability of the hydrophilic layer. It is intended to provide a photosensitive lithographic printing plate.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies in view of such circumstances, and as a result, have found that the above problems can be solved by incorporating titanium oxide fine particles and / or zinc oxide fine particles in a hydrophilic layer. And completed the present invention. That is, the gist of the present invention is to provide, in a direct photosensitive lithographic printing plate having a photosensitive layer containing at least a near-infrared light-to-heat conversion substance and a hydrophilic layer on a substrate, fine particles of titanium oxide and / or oxidized titanium in the hydrophilic layer. A direct photosensitive lithographic printing plate characterized by containing zinc fine particles.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The substrate used in the present invention has a flexibility that can be set in an ordinary lithographic printing machine, and has a function of withstanding a load applied during printing, and specifically, aluminum, zinc, copper, steel, etc. Metal plate, and chrome,
Metal plate, paper, plastic film and glass plate plated or vapor-deposited with zinc, copper, nickel, aluminum, iron, etc., paper coated with resin, paper covered with metal foil such as aluminum, plastic with hydrophilic treatment From among sheets such as films, it can be appropriately selected and used, but preferably, heat generated by the energy of the laser light absorbed by the photosensitive layer is prevented from being transmitted and diffused through the substrate, and the photosensitive layer and It has a function to enhance the effect of ablation of the hydrophilic layer. As described in detail below, the substrate used in the present invention can be used as a base material (hereinafter simply referred to as a base material) itself which is a central element of the structure of the substrate, but for the purpose of adding various functions. And a substrate (hereinafter, referred to as a composite substrate) comprising the base material and an ink-adhesive layer provided on the photosensitive layer side surface (hereinafter, simply referred to as the front surface) and / or a reinforcing layer provided on the back surface. Used.

For the purpose of exhibiting the function of enhancing the effect of the ablation, it is preferable that the base material has a lower thermal conductivity because it has better heat insulating properties, that is, prevents the diffusion of heat. As the substrate used in the present invention, 300K (27
° C) is usually 0.1 W / mK or more and 0.2
W / mK or less, and preferably 0.1 W / mK or more and 0.15 W / mK or less in order to further enhance the effect of preventing thermal diffusion.

In order to suppress the thermal conductivity and increase the heat insulating effect, a material containing a gas such as air in the material of the base material, that is, a material having a low density is preferably used. In order to enhance the heat insulating effect, the density of the substrate is 1.0 g / cm ³
It is necessary to be not less than 2.0 g / cm ³ and
It is preferably from 1.0 g / cm ^{3 to} 1.5 g / cm ³ . When the thermal conductivity and density are significantly larger than the above range, the heat diffusion effect is weak and it is difficult to enhance the ablation effect, and when it is extremely small, the physical strength of the base material is reduced and it may be deformed during printing. .

Specific examples of the substrate include papers such as high-quality paper, resin-treated paper, and coated paper; wood boards; synthetic papers; foams such as expanded polyethylene terephthalate sheets, expanded polypropylene sheets, expanded polyethylene sheets, expanded polystyrene sheets, and the like. Plastic sheets can be mentioned,
From the viewpoints of dimensional stability of the substrate, chemical resistance to solvents and the like contained in the ink, etc., coated paper, art paper, photographic paper base paper, foamed polyethylene terephthalate sheet, foamed polypropylene sheet, and foamed polyethylene sheet are preferred.

In the case where there is a step of washing the printing plate with a cleaning agent containing water at the time of printing, a water-resistant material, that is, foamed plastic or water-resistant paper is preferable. The thickness of the substrate is 10 μm to 3 mm, preferably 20 μm to 1 mm, more preferably 50 μm to 500 μm.
μm. On the surface of the substrate used in the present invention, in order to increase the ink inking property of the image area of the photosensitive lithographic printing plate,
A composite substrate can be manufactured by providing an ink-filling layer having an appropriate cushioning property, a high adhesiveness to an ink roller, and an effect of improving ink transferability.

Specific examples of the ink-adhesive layer include, for example, a polyethylene terephthalate sheet, a foamed polyethylene terephthalate sheet, a polypropylene sheet, a foamed polypropylene sheet, a polyethylene sheet, a foamed polyethylene sheet, and the like. It can be used by bonding to the material surface. Among them, the density is 0.1 g / cm ³ or more and 1.5 g / cm ³ for the purpose of enhancing the heat insulating effect together with the ink inking property.
^Three or more expanded polyethylene terephthalate sheets, expanded polypropylene sheets, and expanded polyethylene sheets are preferred. In addition, the durability of the printing plate is also improved by providing the ink deposition layer.

The thickness of the ink depositable layer is 1 μm to 1 m.
m, preferably 3 μm to 100 μm, more preferably 5 μm
μm to 75 μm. Further, a reinforcing layer is provided on the back surface of the base material used in the present invention for the purpose of enhancing the durability of the printing plate, and a composite substrate can be manufactured. Examples of the reinforcing sheet used for providing the reinforcing layer include: a sheet used for the base material; a sheet used for the ink deposition layer; a metal plate such as an aluminum plate, a copper plate, and an iron plate; an aluminum foil And the like can be appropriately selected from metal foils and the like. Among these, a polyethylene terephthalate sheet, a foamed polyethylene terephthalate sheet, and an aluminum plate are preferred.

The thickness of the reinforcing layer is 10 μm to 3 mm, preferably 20 μm to 1 mm, more preferably 50 μm to 5 mm.
00 μm. Further, in the present invention, it is also possible to produce a composite substrate in which an ink deposition layer is provided on the surface of the substrate and a reinforcing layer is provided on the back surface. As described above, these base material, ink inking layer, and reinforcing layer respectively have a heat insulating effect,
Since the main purpose is ink deposition and durability, in order to improve the performance as a photosensitive printing plate, it is preferable to make use of the respective features and to appropriately form a multilayer so as to compensate for the mutual shortage. For this reason, the same type of material may be bonded to a base material of a certain material as an ink-filling layer and / or a reinforcing layer.
In order to satisfy each of the durability, a material of a grade suitable for the purpose may be appropriately selected. In the case of a composite substrate, it is of course important that the thermal conductivity of the entire composite substrate is low, but it is essential that the substrate itself be heat-insulating in order to at least secure a heat-insulating region. Therefore, it is preferable that the ink deposition layer provided on the surface is also heat-insulating.

As a specific example of a preferred composite substrate used in the present invention, for example, a 20 μm to 75 μm polyethylene terephthalate as an ink-adhesive layer is formed on the surface of art paper, high quality paper, resin processed paper or coated paper of 50 μm to 500 μm. Examples include a sheet, a foamed polyethylene terephthalate sheet, a polypropylene sheet, a foamed polypropylene sheet, a polyethylene sheet, and a laminated sheet of a foamed polyethylene sheet. Further, on the back surface of this composite substrate, as a reinforcing layer, the same type as the ink-injectable sheet or 100 μm to 500 μm
And three layers obtained by laminating an aluminum plate.

When laminating an ink-insulating sheet or a reinforcing sheet on the heat-insulating substrate, one or both of the two sheet surfaces to be laminated may be laminated, for example, as described in JP-A-2-25087. After applying an adhesive such as urethane resin to a thickness of 0.1 to 10 μm,
0 to 150 ° C, 0.1 to 50 kg / cm ² , 0.1 to 5
Lamination is performed under the condition of 0 m / s, and an ink-insulating layer or a reinforcing layer is formed on the heat-insulating substrate.

As described in detail above, in the present invention, the substrate means a layer which should be the main heat-insulating function in the structure of the substrate depending on its physical properties and layer thickness. The relationship between the layer configuration and the substrate can be modified to a degree that can be conceived by those skilled in the art. For example, the heat insulating function is almost equally borne between the base material and the ink deposition layer, or the base material itself is compounded, and the heat insulating function specified in the present invention is expressed in an integrated manner, and as required. Other layers could be interposed.

The photosensitive layer used in the present invention comprises 6
At the same time, the light of 00 to 1300 nm is efficiently absorbed and converted into heat to cause ablation of the photosensitive layer to remove the photosensitive layer, and at the same time, to induce ablation of the hydrophilic layer in response to the heat generated thereby, to melt, volatilize or Burn,
And / or a near-infrared light-to-heat conversion material having a function of removing the photosensitive layer by pressure during ablation.

The near-infrared light-to-heat conversion material (hereinafter simply referred to as light-to-heat conversion material) used in the photosensitive layer of the present invention is not particularly limited as long as it is a substance that generates heat by light irradiation.
More specifically, organic or inorganic pigments having an absorption band in part or all of the wavelength range of 650 to 1300 nm described in Japanese Patent Application No. 10-23104, organic dyes,
Metal and the like. Specifically, for example, carbon black, graphite; metals such as titanium and chromium; metal oxides such as titanium oxide, tin oxide, zinc oxide, vanadium oxide, and tungsten oxide; metal carbides such as titanium carbide; metal borides; Inorganic black pigments described in JP-A-4-322219, azo black pigments,
Black or green organic pigments such as "Lionol Green 2YS" and "Green Pigment 7" are exemplified.

Examples of the above-mentioned carbon black include "MA-7" and "MA-1" which are products of Mitsubishi Chemical Corporation.
00 "," MA-220 ","# 5 ","# 10 ",
“# 40”, “Color Black FW2”, “FW20”, “Printex V”, etc., which are products of Degussa Corporation. In addition, "Special Function Dyes" (edited by Ikemori and Pillar Valley,
1986, published by CMC Co., Ltd.), "Chemistry of Functional Dyes" (edited by Higaki, 1981, published by CMC Co., Ltd.), "Dye Band Book" (edited by Okawa, Hirashima, Matsuoka, Kitao, published by Kodansha) ), Japan Photographic Dye Institute, 1995
Exciton Inc., a catalog published in 2005. Is 1
Dyes having absorption in the near-infrared region described in a laser dye catalog issued in 989 and the like can be mentioned.

Further, JP-A-2-2074, JP-A-2-2074
5, 2076, JP-A-3-97590, 9759
No. 1, No. 63185, No. 26593, No. 97589
And organic dyes described in each of the above publications. or,
Preferred near-infrared light-to-heat conversion materials in the present invention include:
This is a near-infrared cyanine-based dye, which has a heterocyclic ring containing a nitrogen atom, an oxygen atom, a sulfur atom, or the like, and a polymethine (-
A so-called cyanine-based dye in a broad sense linked by CH =) _n , for example, quinoline-based (so-called cyanine-based), indole-based (so-called indocyanine-based), benzothiazole-based (so-called thiocyanine-based), imino Various dyes such as cyclohexadiene type (so-called polymethine type), pyrylium type, thiapyrylium type, squarylium type, croconium type, azurenium type are exemplified. Systems or thiapyrylium systems are preferred. In the present invention, among the cyanine-based dyes, quinoline-based dyes include, particularly, compounds represented by the following general formula (I)
Those represented by a), (Ib) or (Ic) are preferred.

[0022]

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[In the formulas (Ia), (Ib) and (Ic),
R ¹ and R ² are each independently an alkyl group optionally having a substituent, an alkenyl group optionally having a substituent, an alkynyl group optionally having a substituent, or a substituent Represents a phenyl group which may have a substituent, L ¹ represents a tri, penta or heptamethine group which may have a substituent, and two substituents on the penta or heptamethine group are connected to each other A cycloalkene ring having 5 to 7 carbon atoms may be formed, and the quinoline ring may have a substituent. In this case, two adjacent substituents are connected to each other to form a fused benzene ring. May be. X ^- represents a counter anion]

Here, the formulas (Ia), (Ib) and (I
Examples of the substituent for R ¹ and R ² in c) include an alkoxy group, a phenoxy group, a hydroxy group, and a phenyl group. Examples of the substituent for L ¹ include an alkyl group, an amino group, and a halogen atom. And examples of the substituent in the quinoline ring include an alkyl group, an alkoxy group, a nitro group, and a halogen atom. or,
Indole and benzothiazole dyes include
Particularly, those represented by the following general formula (II) are preferable.

[0025]

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[In the formula (II), Y ¹ and Y ² each independently represent a dialkylmethylene group or a sulfur atom, and R ³ and R ⁴ each independently may have a substituent. An alkyl group, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a phenyl group which may have a substituent, and L ² has a substituent Represents an optionally tri, penta, or heptamethine group,
Two substituents on the penta or heptamethine group may be connected to each other to form a cycloalkene ring having 5 to 7 carbon atoms, and the condensed benzene ring may have a substituent. Two adjacent substituents may be linked to each other to form a fused benzene ring. X ^- represents a counter anion]

Here, examples of the substituent for R ³ and R ⁴ in the formula (II) include an alkoxy group, a phenoxy group, a hydroxy group and a phenyl group. The substituent for L ² is an alkyl group , An amino group, or a halogen atom. Examples of the substituent on the benzene ring include an alkyl group, an alkoxy group, a nitro group, and a halogen atom. As the iminocyclohexadiene-based dye, those represented by the following general formula (III) are particularly preferable.

[0028]

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[In the formula (III), R ⁵ , R ⁶ , R ⁷ and R ⁸
Each independently represents an alkyl group; R ⁹ and R ¹⁰ each independently represent an aryl group, a furyl group, or a thienyl group which may have a substituent; and L ³ has a substituent. Represents a mono, tri, or pentamethine group which may be substituted, and two substituents on the tri or pentamethine group may be connected to each other to form a cycloalkene ring having 5 to 7 carbon atoms. X ^- represents a counter anion]

Here, specific examples of R ⁹ and R ¹⁰ in the formula (III) include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-furyl group, a 3-furyl group and a 2-thienyl group. ,
3-thienyl group and the like, and as a substituent thereof, an alkyl group, an alkoxy group, a dialkylamino group,
Hydroxy group, or a halogen atom, and examples of the substituent in L ^3, alkyl group, amino group, or a halogen atom. Further, as the pyrylium-based and thiapyrylium-based dyes, particularly, the following general formula (V)
Those represented by a), (IVb) or (IVc) are preferred.

[0031]

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[In the formulas (IVa), (IVb) and (IVc),
Y ³ and Y ⁴ each independently represent an oxygen atom or a sulfur atom, and R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represent a hydrogen atom or an alkyl group, or R ¹¹ and R ¹³ and R ¹² and R ¹⁴
May be linked to each other to form a cycloalkene ring having 5 or 6 carbon atoms, and L ⁴ represents a mono, tri, or pentamethine group which may have a substituent, and May be linked to each other to form a cycloalkene ring having 5 to 7 carbon atoms, and the pyrylium ring and the thiapyrylium ring may have a substituent. The substituents may be linked to each other to form a fused benzene ring. X ^- represents a counter anion]

Here, the formulas (IVa), (IVb) and (IV
Examples of the substituent for L ⁴ in c) include an alkyl group, an amino group, and a halogen atom. Examples of the substituent on the pyrylium ring and the thiapyrylium ring include an aryl group such as a phenyl group and a naphthyl group. that's all,
Quinoline dyes represented by formulas (Ia) to (Ic), indole or benzothiazole dyes represented by formula (II), iminocyclohexadiene represented by formula (III) A dye, and the general formula (IVa)
Specific examples of the pyrylium-based or thiapyrylium-based dyes represented by (IVc) are shown below.

[0034]

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[0035]

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The counter anion X in the above general formula^-Concrete
As shown, for example, Cl^-, Br ^-, I^-, ClO_Four
^-, BF_Four ^-, PF_Five ^-Inorganic acid anions such as benzene
Sulfonic acid, p-toluenesulfonic acid, naphthalenesul
Examples of organic acid anions such as fonic acid, acetic acid and organic boric acid
Can be In particular, the organic borate anion is a counter ion
Because the dye has excellent solubility in the coating solvent,
It facilitates the production of coating solutions and uses low-boiling solvents.
Application line roller for wet photosensitive layer because it can be used
It is possible to suppress the occurrence of sticking to the surface, and it is possible to perform high-speed application.
And high productivity can be obtained. Specifically like this
The organic borate anion is represented by the following formula (L).
Are included.

[0037]

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(Wherein, R ^{Q1 to} R ^Q4 each represent a hydrogen atom,
Represents an alkyl group having 1 to 15 carbon atoms, an aromatic hydrocarbon group having 6 to 15 carbon atoms which may have a substituent, or a heterocyclic group having 4 to 15 carbon atoms which may have a substituent. More specifically, R ^{Q1 to} R ^Q4 are each -CH ₃ ,-
_{C 2 H 5, -C 3 H} 7, -C 4 H 9, -C 4 H 9 -t,

[0039]

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And the like. Further, other preferable specific examples other than the above-mentioned cyanine dye include: S-1 nigrosine dye: Color Index Solvent Black
5 S-2 Nigrosine dye: Color Index Solvent Black
7 S-3 Nigrosine dye: Color Index Acid Black 2 S-4 Carbon black: MA-100 (manufactured by Mitsubishi Chemical Corporation) S-5 Titanium monoxide: Titanium black 13M (manufactured by Mitsubishi Materials Corporation) S-5 Titanium monoxide: Titanium black 12S (manufactured by Mitsubishi Materials Corporation) can be mentioned.

These light-to-heat converting substances are blended in an amount of 5 to 100% by weight based on the total solid content of the photosensitive composition of the present invention.
Preferably 10 to 98% by weight, more preferably 20 to 9% by weight.
5% by weight. In the photosensitive layer, if necessary,
A coloring material other than the light-to-heat conversion substance can be contained. As the coloring material, a pigment or a dye is used. For example, Victoria Pure Blue (42595), Auramine O (41000), Katilon Brilliant Flavin (Basic 13), Rhodamine 6GCP (4516)
0), Rhodamine B (45170), Safranin OK7
0: 100 (50240), Erioglaucine X (42
080), First Black HB (26150), N
o. 120 / Lionol Yellow (21090), Lionol Yellow GRO (21090), Shimla Fast Yellow 8GF (21105), Benzidine Yellow 4T-564D (21095), Shimla Fast Red 4015 (12355), Lionol Red B4
401 (15850), Fast Gen Blue TGR-
L (74160), Lionol Blue SM (2615
0) and the like. The numbers in parentheses above indicate the color index (CI).

When the coloring material is contained, its compounding ratio is from 0 to 50% by weight, preferably from 1 to 30% by weight, based on the total solid content of the photosensitive layer composition.

The thickness of the photosensitive layer is 0.05 to 100 μm.
m, preferably 0.1 to 30 μm, more preferably 0.3 to 10 μm. Alternatively, a photosensitive layer composed of a light absorbing agent can be provided directly on the substrate by vapor deposition or sputtering of the light absorbing agent. In this case, the film thickness is 0.01 to 0.5 μm, preferably 0.02 to 0.5 μm.
0.4 μm.

In the photosensitive layer used in the present invention, in addition to the above-mentioned light absorbing agent, the purpose is to enhance the coating properties, compatibility with the light absorbing agent, the film strength in the photosensitive layer, and the effect of ablation. Thus, an organic polymer substance can be added. Examples of the organic polymer include unsaturated acids such as (meth) acrylic acid and itaconic acid, and alkyl (meth) acrylate,
Copolymers with phenyl (meth) acrylate, benzyl (meth) acrylate, styrene, α-methylstyrene and the like;
Polymers of alkyl methacrylate or alkyl acrylate represented by polymethyl methacrylate; copolymers of alkyl (meth) acrylate with acrylonitrile, vinyl chloride, vinylidene chloride, styrene, etc .; copolymers of acrylonitrile with vinyl chloride or vinylidene chloride Modified cellulose having a carboxyl group in the side chain; polyethylene oxide; polyvinylpyrrolidone; phenol, o-,
Novolak resin obtained by condensation reaction of m-, p-cresol and / or xylenol with aldehyde, acetone, etc .; polyether of epichlorohydrin and bisphenol A; soluble nylon; polyvinylidene chloride; chlorinated polyolefin; Copolymer of vinyl and vinyl acetate; vinyl acetate polymer; copolymer of acrylonitrile and styrene; copolymer of acrylonitrile with butadiene and styrene; polyvinyl alkyl ether; polyvinyl alkyl ketone; polystyrene;
Polyethylene terephthalate isophthalate; acetylcellulose; acetylpropoxycellulose; acetylbutoxycellulose; celluloid; polyvinyl butyral and the like are used. The compounding ratio of the organic polymer substance in the photosensitive layer is from 0 to 95% by weight of the total solid content of the photosensitive layer,
It is preferably 2-90% by weight, more preferably 5-80% by weight.
% By weight.

In the photosensitive layer, various additives having a hydrophobic group, for example, p-octylphenol / formalin novolak resin, for the purpose of enhancing the ink adhesion of the printing ink,
p-butylphenol / formalin novolak resin, p
-T-butylphenol-benzaldehyde resin, modified novolak resin such as rosin-modified novolak resin,
Further, o-naphthoquinonediazidosulfonic acid esters of these modified novolak resins, fluorine-based surfactants are added, and nitro compounds such as self-oxidizing nitrocellulose, carbonate compounds, sodium nitrate, etc. Nitrate such as ammonium nitrate, peroxide such as benzoyl peroxide and perbenzoic acid ester, or azo compounds such as foamable azodicarbonamide and azobisisobutyronitrile; N, N'-dinitropentamethylenetetramine and the like. Nitroso compounds, p-toluenesulfonylhydrazine, sulfonylhydrazide compounds such as p, p'-oxybis (benzenesulfohydrazine) and the like are used in an amount of 0 to 70% by weight, preferably 0 to 60% by weight, based on the total solid content of the photosensitive layer. More preferably 5-
It can be used by adding 60% by weight.

In the present invention, among the compounds that enhance the ablation effect, nitrocellulose described below is preferably used. The nitrocellulose used in the present invention is a silicone rubber provided on a photosensitive layer by being decomposed by heat generated by absorption of a near-infrared laser beam by a light-to-heat conversion substance to efficiently generate a low-molecular gas. It has a function of promoting removal of the laser-exposed portion of the layer.

The nitrocellulose is obtained by nitrating natural cellulose purified by an ordinary method with a mixed acid,
It is obtained by introducing a part or all of a nitro group into three hydroxyl groups present in a glucopyranose ring which is a constitutional unit of cellulose. The nitrification degree of the nitrocellulose used in the present invention is 2 to 13, preferably 10 to 12.5, and more preferably 11 to 1.
2.5. Here, the degree of nitrification indicates the weight% of nitrogen atoms in nitrocellulose. If the degree of nitrification is extremely high,
Although the effect of accelerating ablation is enhanced, the stability at room temperature tends to decrease, and the nitrocellulose becomes explosive, which poses a danger in handling the nitrocellulose when producing a printing plate. If the nitrification degree is extremely low, the effect of accelerating ablation cannot be sufficiently obtained.

The degree of polymerization of the nitrocellulose is 20
２００200, preferably 25-150. If the degree of polymerization is extremely high, the removal of the hydrophilic layer provided on the upper layer will be incomplete, and the ink adhesion of the laser-exposed portion (image portion) tends to be poor. If the degree of polymerization is extremely low, the coating properties of the photosensitive layer will be poor and the hydrophilic layer will tend to peel off.

The mixing ratio of the nitrocellulose in the photosensitive layer is from 0 to 80% by weight, preferably from 10 to 70% by weight, more preferably from 30 to 7% by weight, based on the total solid components of the photosensitive layer.
0% by weight. The hydrophilic layer used in the present invention is in a state (wet state) in which the surface is covered with a thin film of water by dampening water supplied at the time of printing, and becomes lipophilic when it comes into contact with the printing ink in an emulsion state. Has a function of preventing the adhesion of the ink particles and forming a non-image portion on the printed matter.

The hydrophilic layer contains titanium oxide and / or zinc oxide in order to exhibit good hydrophilicity. The titanium oxide (TiO ₂ ) is an anatase type,
There is a rutile type crystal type, which can be used together, but an anatase type is preferable because it is easy to make fine particles, and a hexagonal type is preferable as zinc oxide (ZnO ₂ ). The particle size is 10 μm or less, preferably 1 nm to 5 μm. The mixing ratio of the titanium oxide and / or zinc oxide is such that the total content of the titanium oxide fine particles and the zinc oxide fine particles is 30 to 100% by weight, preferably 40 to 90% by weight based on the total solid content in the hydrophilic layer. %,
More preferably, it is 50 to 80% by weight.

Next, the titanium oxide or zinc oxide is fixed in the hydrophilic layer by various methods. Examples of the fixing method include a vapor deposition method and 1) a method of curing by moisture in air. UV-curable silane-based coupling agent (crosslinking agent) and titanate-based coupling agent (crosslinking agent), aluminate-based coupling agent (crosslinking agent), which can be cured by ultraviolet rays, or 2) hydrophilic binder polymer And a method in which the fixing agent is mixed at the time of coating the hydrophilic layer. More specifically, as the silane coupling agent of 1), methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-t-butoxysilane; ethyltrichlorosilane; Ethyltribromosilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri-t-butoxysilane; n-propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyl Triethoxysilane, n-propyltriisopropoxysilane, n-
N-hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane; n-decyltrichlorosilane, n-decyltribromosilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, n-
Decyltriisopropoxysilane, n-decyltri-t-
Butoxysilane; n-octadecyltrichlorosilane,
n-octadecyltribromosilane, n-octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n
-Octadecyltri-t-butoxysilane; phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, phenyltri-t-butoxysilane; tetrachlorosilane, tetrabromosilane, tetramethoxy Silane, tetraethoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane; dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane, dimethyldiethoxysilane; diphenyldichlorosilane, diphenyldibromosilane,
Diphenyldimethoxysilane, diphenyldiethoxysilane; phenylmethyldichlorosilane, phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxy Hydrosilane, tri-t-butoxyhydrosilane; vinyltrichlorosilane, vinyltribromosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltri-t-butoxysilane; trifluoropropyltrichlorosilane, trifluoropropyltribromo Silane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trif Oro propyl triisopropoxysilane, trifluoropropyl tri t- butoxysilane;
γ-glycidoxypropylmethyldimethoxysilane, γ
-Glycidoxypropylmethyldiethoxysilane, γ-
Glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriisopropoxysilane, γ-glycidoxypropyltri-t-butoxysilane, γ-methacryloxypropylmethyldimethoxysilane Γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltriisopropoxysilane, γ-methacryloxypropyltri t-butoxysilane; γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ
-Aminopropyltriisopropoxysilane, γ-aminopropyltri-t-butoxysilane; γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane Γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane; β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; β- (3,4-epoxycyclohexyl) ethyltriethoxysilane; Partial hydrolysates thereof; and mixtures thereof.

Examples of titanate-based coupling agents include tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and the like. As an aluminum-based coupling agent,

[0053]

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And the like. Examples of the hydrophilic binder polymer of 2) include a carboxyl group, an amino group, a phosphoric acid group, a sulfonic acid group, or a salt, a hydroxyl group, or an amide of a polymer composed of carbon-carbon bonds as a side chain. Group, a networked polymer containing one or more hydrophilic functional groups such as polyoxyethylene groups or a plurality thereof, or one of carbon atoms, carbon-carbon bonds, at least one or more of oxygen, nitrogen, sulfur, Carboxyl group, amino group, phosphoric acid group, sulfonic acid group, or a salt thereof, hydroxyl group, amide group, hydrophilic functional group such as polyoxyethylene group or the like in the polymer or the side chain linked by the hetero atom composed of phosphorus. It is a polymer containing at least one kind and a plurality of polymers, specifically, a poly (meth) acrylate-based, polyoxyalkylene-based, polyurethane-based, Epoxy ring-opening addition polymerization type, poly (meth) acrylic acid, poly (meth) acrylamide, polyester,
Examples thereof include polymers of polyamide type, polyamine type, polyvinyl type, polysaccharide type or cellulose derivative type.
Among them, any one of a hydroxyl group, a carboxyl group or an alkali metal salt thereof, an amino group or a hydrogen halide salt thereof, a sulfonic acid group or an amine thereof, an alkali metal salt, an alkaline earth metal salt, an amide group or a amide group on a segment side chain. And those having a hydrophilic functional group and a polyoxyethylene group partially overlapped with the main chain segment are preferable because of high hydrophilicity. In addition to these, those having a urethane bond or a urea bond in the main chain or side chain of the hydrophilic binder polymer are more preferable because not only the hydrophilicity but also the printing durability of the non-image area are improved.

The hydrophilic binder polymer used in the present invention may contain various other components described below, if necessary. Specific examples of the hydrophilic binder polymer of the present invention are shown below. (Meth) acrylic acid or its alkali, amine salt, itaconic acid or its alkali, amine salt, 2-hydroxyethyl (meth) acrylate,
(Meth) acrylamide, N-monomethylol (meth)
Acrylamide, N-dimethylol (meth) acrylamide, 3-vinylpropionic acid or its alkali,
Amine salts, vinylsulfonic acid or its alkali,
Amine salt, 2-sulfoethyl (meth) acrylate, polyoxyethylene glycol mono (meth) acrylate, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxypolyoxyethylene glycol mono (meth) acrylate, allylamine or halogenated thereof Use at least one of hydrophilic monomers having a hydrophilic group such as a hydroxyl group such as a hydrochloride, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, phosphoric acid or a salt thereof, an amide group, an amino group, and an ether group. To synthesize a hydrophilic homo- or copolymer.

The hydrophilic binder polymer having a functional group such as a hydroxyl group, a carboxyl group, an amino group or a salt thereof, or an epoxy group in the hydrophilic polymer utilizes these functional groups to form a vinyl group, an allyl group, a (meth) acrylic group. An ethylene addition polymerizable unsaturated group such as a group or a cinnamoyl group,
An unsaturated group-containing polymer into which a ring-forming group such as a cinnamylidene group, a cyanosinnamylidene group or a p-phenylenediacrylate group is introduced is obtained. If necessary, a monofunctional or polyfunctional monomer copolymerizable with the unsaturated group, a polymerization initiator described below, and other components described below are added, and the mixture is dissolved in an appropriate solvent to adjust a dope. This is coated on a support and subjected to three-dimensional crosslinking after drying or also as drying.

A hydrophilic binder polymer containing an active hydrogen such as a hydroxyl group, an amino group or a carboxyl group is added to the above active hydrogen-free solvent together with an isocyanate compound or a blocked polyisocyanate compound and other components described below to prepare a dope. Then, it is applied to a support and reacted after drying or while also drying to form a three-dimensional crosslink. Glycidyl (meth) as a copolymer component of the hydrophilic binder polymer
A monomer having a glycidyl group such as acrylate and a carboxyl group such as (meth) acrylic acid can be used in combination. The hydrophilic binder polymer having a glycidyl group, as a crosslinking agent, 1,2-ethanedicarboxylic acid,
Α, ω-alkane or alkenedicarboxylic acid such as adipic acid, 1,2,3-propanetricarboxylic acid,
Polycarboxylic acids such as trimellitic acid, 1,2-ethanediamine, diethylenediamine, diethylenetriamine,
polyamine compounds such as α, ω-bis- (3-aminopropyl) -polyethylene glycol ether, oligoalkylenes or polyalkylene glycols such as ethylene glycol, propylene glycol, diethylene glycol and tetraethylene glycol, trimethylolpropane, glycerin, pentaerythritol; Using a polyhydroxy compound such as sorbitol, a three-dimensional crosslinking can be carried out by utilizing a ring opening reaction with these.

The hydrophilic binder polymer having a carboxyl group or an amino group may be used as a crosslinking agent such as ethylene or propylene glycol diglycidyl ether, polyethylene or polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether,
Three-dimensional crosslinking can be performed by using an epoxy ring-opening reaction using a polyepoxy compound such as 1,6-hexanediol diglycidyl ether or trimethylolpropane triglycidyl ether.

Polysaccharides such as cellulose derivatives, polyvinyl alcohol or partially saponified products thereof, glycidol homo- or copolymers, or hydrophilic binder polymers based on these are used for the above-mentioned functional groups capable of undergoing a cross-linking reaction by utilizing the hydroxyl groups contained therein. Groups can be introduced to provide a three-dimensional crosslinked structure in the manner described above. Polyol containing hydroxyl group or amino group at the polymer terminal such as polyoxyethylene glycol or polyamine and polyisocyanate such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate The hydrophilic polyurethane precursor synthesized from the above can be three-dimensionally crosslinked by the above-mentioned method using a polymer in which an ethylene addition polymerizable unsaturated group or a ring-forming group is introduced.

The synthesized hydrophilic polyurethane precursor is
When it has an isocyanate group terminal, glycerol mono (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, N-monomethylol (meth) acrylamide, N-dimethylol (meth) acrylamide, Compounds having active hydrogen such as (meth) acrylic acid, cinnamic acid, and cinnamic alcohol, or (meth) acrylic acid, glycidyl (meth) acrylate, 2-isocyanatoethyl ( (Meth) acrylate and the like.

After the application of the polybasic acid and the polyol or the polybasic acid and the polyamine, the network structure is formed by three-dimensional cross-linking by heating, or the three-dimensional cross-linking of a water-soluble colloid-forming compound such as casein, glue or gelatin by heating. May be formed. Furthermore, hydroxyl- and amino-group-containing hydrophilic compounds such as homo- or copolymers synthesized from hydroxyl-containing monomers such as 2-hydroxyethyl (meth) acrylate and vinyl alcohol, and allylamines, polysaccharides such as partially saponified polyvinyl alcohol, and cellulose derivatives, and glycidol homo or copolymers. There is also a method of forming a three-dimensionally cross-linked hydrophilic binder polymer by reacting a hydrophilic polymer with a polybasic acid anhydride having two or more acid anhydride groups in one molecule.

Examples of polybasic acid anhydrides include ethylene glycol bisanhydrotrimellitate, glycerol trisanhydrotrimellitate, 1,3,3a, 4,5
9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-C] furan-1,3-dione, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic Examples thereof include acid dianhydride and 1,2,3,4-butanetetracarboxylic dianhydride.

An active hydrogen-containing compound, such as a polyamine or a polyol, having an isocyanate group at the end, and other components described below are dissolved or dispersed in a solvent, coated on a support, and the solvent is removed. It can be cured and three-dimensionally crosslinked. In this case, hydrophilicity may be imparted by introducing a hydrophilic functional group into either or both segments and side chains of the polyurethane or the active hydrogen-containing compound. The segment and the functional group that express hydrophilicity may be appropriately selected from the above description.

Examples of the polyisocyanate compound that can be used include 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, Bicycloheptane triisocyanate can be exemplified.

In handling before and after the coating step, it is sometimes preferable to block (mask) the isocyanate group by a known method in order to prevent the isocyanate group from changing. For example, Keiji Iwata, "Plastic Materials Course Polyurethane Resin", Nikkan Kogyo Shimbun (1974), pp. 51-52, Keiji Iwata, "Polyurethane Resin Handbook", Nikkan Kogyo Shimbun (198)
7), pages 98, 419, 423, 499, etc., sodium acid sulfite, aromatic secondary amine, tertiary alcohol, amide, phenol, lactam, heterocyclic compound, ketoxime and the like can be used. It is preferable that the isocyanate regeneration temperature is low and hydrophilic, and examples thereof include sodium acid sulfite.

An addition-polymerizable unsaturated group may be introduced into any of the above-mentioned unblocked or blocked polyisocyanates and used for strengthening crosslinking or reacting with lipophilic components. The degree of the degree of cross-linking, such as the average molecular weight between cross-links, varies depending on the type of segment used, the type and amount of the associative functional group, and the like, but may be determined according to the required printing durability. Normal,
The average molecular weight between crosslinks is set in the range of 500 to 50,000.
If it is shorter than 500, it tends to become brittle. 80 on balance of printing durability and hydrophilicity
It is practical to use about 0 to 30,000, and more preferably about 1,000 to 10,000.
The hydrophilic binder polymer of the present invention may be used in combination with the following monofunctional monomers and polyfunctional monomers.

More specifically, Shinzo Yamashita and Tosuke Kaneko, “Handbook of Crosslinking Agents”, Taiseisha (1981), and Kiyomi Kato, “Ultraviolet Curing System”, published by Sogo Gijutsu Center (198).
9), edited by Kiyomi Kato, "UV / EB Curing Handbook (raw material)", Polymer Publishing Association (1985), supervised by Kiyoshi Akamatsu, "Practical technology of new photosensitive resin", CMC, pp. 102-14,
(1987), N, N'-methylenebisacrylamide, (meth) acryloylmorpholine,
Vinylpyridine, N-methyl (meth) acrylamide,
N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N
-Dimethylaminoethyl (meth) acrylate, N, N
-Diethylaminoethyl (meth) acrylate, N, N
-Dimethylaminoneopentyl (meth) acrylate,
N-vinyl-2-pyrrolidone, diacetone acrylamide, N-methylol (meth) acrylamide, p-styrenesulfonic acid and a salt thereof,

Methoxytriethylene glycol (meth)
Acrylate, methoxytetraethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate (PEG has a number average molecular weight of 40
0), methoxypolyethylene glycol (meth) acrylate (number average molecular weight of PEG 1000), butoxyethyl (meth) acrylate, phenoxyethyl (meth)
Acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, nonylphenoxyethyl (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, polyethylene glycol di (meth) acrylate (PEG number average molecular weight 400 ), Polyethylene glycol di (meth) acrylate (PEG
Number average molecular weight 600), polyethylene glycol di (meth) acrylate (PEG number average molecular weight 100
0), polypropylene glycol di (meth) acrylate (PEG number average molecular weight 400),

2,2-bis [4- (methacryloxyethoxy) phenyl] propane, 2,2-bis [4- (methacryloxydiethoxy) phenyl] propane, 2,2
-Bis [4- (methacryloxypolyethoxy) phenyl] propane or its acrylate, β- (meth)
Acryloyloxyethyl hydrogendiene phthalate,
β- (meth) acryloyloxyethyl hydrogen succinate, polyethylene or polypropylene glycol mono (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate,

Tetramethylolmethane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, isobornia (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, isodecyl (meth) acrylate , Cyclohexyl (meth) acrylate, tetrafurfuryl (meth) acrylate, benzyl (meth) acrylate, mono (2-acryloyloxyethyl) acid phosphate or its methacrylic body, glycerin mono- or di (meth) acrylate,
Tris (2-acryloxyethyl) isocyanurate or its methacrylic product, N-phenylmaleimide, N-
(Meth) acryloxysuccinimide, N-vinylcarbazole, divinylethyleneurea, divinylpropyleneurea and the like.

The mixing ratio of these fixing agents is from 0 to 70% by weight, preferably from 0 to 60% by weight, based on the total solid content of the hydrophilic layer. The hydrophilic layer used in the present invention has a particle diameter of 10 to 4 for the purpose of improving the water retention of the dampening solution.
0 nm colloidal silica, colloidal alumina having a particle size of 10 to 100 nm, acetic acid, formic acid, citric acid, tartaric acid, malic acid, carboxylic acid such as itaconic acid or a carboxylate alone or a mixture thereof is used as the whole of the hydrophilic layer. It can be contained at a compounding ratio of 0 to 50% by weight, preferably 0 to 40% by weight based on the solid content.

Further, in the hydrophilic layer, a suitable surfactant is added for the purpose of improving the coating property on the photosensitive layer.
0.01 to 10 based on the total solid content of the hydrophilic layer coating solution
It can be contained at a blending ratio of% by weight. In the hydrophilic layer used in the present invention, in order to facilitate the removal of the hydrophilic layer at the time of ablation of the photosensitive layer, the photothermal conversion substance used in the photosensitive layer relative to the total solid content of the hydrophilic layer 0
It can be contained at a blending ratio of 50% by weight, preferably 0 to 30% by weight.

The thickness of the hydrophilic layer used in the present invention is
It is 0.1 to 100 μm, preferably 0.2 to 50 μm, and more preferably 0.5 to 20 μm. The present invention provides a direct photosensitive printing plate having the above-described photosensitive layer and hydrophilic layer provided on a substrate, a semiconductor laser beam oscillating light of 600 to 1200 nm or a light source equivalent thereto, such as a xenon flash or a light emitting diode. Focus the light density,
5 MW / m ² or more, preferably 10 MW / m ² or more, more preferably 20 MW / m ² or more, especially 100 MW / m ²
Scanning exposure is performed using a beam spot of m ² or more, and an exposed portion is ablated to form an image. The beam diameter is usually 5 to 30 μm. The photosensitive lithographic printing plate of the present invention is used as a printing plate without post-processing after ablation, and removes fine particles of a photosensitive layer or a hydrophilic layer generated by ablation attached to the exposed printing plate. For the purpose, post-treatment may be performed by applying a physical stimulus such as a brush, a pad, an ultrasonic wave or a spray while supplying an aqueous solution or an organic solvent to the surface of the hydrophilic layer as necessary.

As another method for removing the fine particles generated by the ablation, a hydrophilic layer of a photosensitive printing plate after exposing a cover sheet having a surface having higher adhesion to the fine particles than the hydrophilic layer can be used. Above, a method of peeling after laminating so that the hydrophilic surface and the adhesive cover sheet surface fit together, and before exposure, the cover sheet is a cover sheet that transmits laser light in the same manner as described above, Examples of the method include peeling after exposure and a method of removing fine particles on the hydrophilic layer. Examples of the cover sheet include those provided with an adhesive layer such as silicone rubber, ionomer, and vinyl acetate on a substrate such as polyethylene terephthalate, polypropylene, polycarbonate, or paper as needed.

[0075]

(Photosensitive layer composition)

Light absorber: Compound described in Table 1 Compounding amount described in Table 1 Organic polymer substance: Compound described in Table 1 Compounding amount described in Table 1 Additive: Compound described in Table 1 Compounding amount shown in Table 1 Coating solvent: cyclohexanone 500 parts by weight N-methylpyrrolidone 400 parts by weight After coating, the coating was dried at 85 ° C. for 3 minutes to provide a photosensitive layer having a dry film thickness of 1.5 μm. Subsequently, a hydrophilic layer composition having the composition shown in Table 1 was applied onto the photosensitive layer.

[Hydrophilic layer composition] PA-1: 40 parts by weight of titanium oxide (Nissan Chemical Co., TA-15, particle size 15 nm) silica sol (Glaska manufactured by Nippon Synthetic Rubber Co., Ltd.) 30 〃 silane coupling agent (trimethoxymethyl) Silane) 10 エ タ ノ ー ル Ethanol 500 （PA-2: Titanium oxide (manufactured by Nippon Print Ink Co., Ltd., 50 parts by weight PW-157, particle size 0.2 μm) Hydrophilic binder polymer Water 900 parts by weight PA-3: Titanium oxide (manufactured by Holbein Industries, 40 parts by weight W203 Titanium White, particle size 0.5 μm hydrophilic binder polymer 900 parts by weight of water PA-4: 100 parts by weight of polyvinyl alcohol (GL-05, manufactured by Nippon Synthetic Chemical Company) 900 parts by weight of water PA-5: zinc oxide (two kinds of zinc oxide, manufactured by Sakai Chemical Industry Co., Ltd .; 5 μm) 50 parts by weight hydrophilic binder polymer Water 900 parts by weight PA-6: Zinc oxide (fine zinc oxide, particle size 0.25 μm, manufactured by Sakai Chemical Industry Co., Ltd.) 50 parts by weight Hydrophilic binder polymer 900 parts by weight of water

After the application, the coating was dried at 100 ° C. for 4 minutes to provide a hydrophilic layer having a dry film thickness of 1.2 μm to prepare a photosensitive printing plate. The photosensitive printing plate is placed on a rotating drum having a circumference of 20 cm.
The fixing was performed so that the hydrophilic layer was on the outside, and the drum was rotated. Next, on the rotating printing plate, 830 nm, 30 m
W semiconductor laser light (manufactured by Hitachi, Ltd., HL8325
G) was condensed to a beam diameter of 30 μm and subjected to scanning exposure (corresponding to about 133 MW / m ² ). Subsequently, the following items were evaluated. Table 1 shows the results.

[Sensitivity] The printing plate was scanned and exposed while rotating the rotating drum at various rotation speeds.
Observed with a microscope at × magnification, the hydrophilic layer
The sensitivity was evaluated based on the maximum scanning speed (cm / s) to be removed. The higher the scanning speed, the higher the sensitivity.

[Ink Smear of Non-image Area] On a printing plate subjected to laser exposure at the maximum exposure speed, a sponge to which a developing ink (Developing Ink PI-2, manufactured by Fuji Photo Film Co., Ltd.) is adhered is used. After the rubbing treatment, the printing plate was washed with water, and the non-image portion of the printing plate was evaluated for ink stainability from the state of ink deposition on the non-image portion. A: Ink adheres to less than 1% of the non-image area. B: Ink adheres to 1% or more to less than 5% of the non-image area. C: Ink adheres to 5% or more and less than 10% of the non-image area. D: Ink adheres to 10% or more of the non-image area.

[0080]

[Table 1]

In Table 1, the abbreviations in the column of substrate represent the following substrates, respectively. [Substrate] K-1 : A foamed polypropylene sheet having a thickness of 140 μm and a density of 0.8 g / cm ³ (manufactured by Oji Yuka Synthetic Paper, GWG) K-2 : An art having a thickness of 100 μm and a density of 1.1 g / cm ³ 35 μm thickness, density 1.
A composite substrate laminated with a 2 g / cm ³ foamed polyethylene terephthalate sheet. K-3 : Art paper (heat insulating base material) having a thickness of 100 μm and a density of 1.1 g / cm ³ , a thickness of 25 μm and a density of 0.1 μm.
Composite substrate laminated with a foamed polypropylene sheet of 94 g / cm ³ . K-4 : A composite substrate in which a 140 μm thick foamed polypropylene sheet (manufactured by Oji Yuka Synthetic Paper, GWG) is laminated on a 0.2 mm aluminum sheet. K-5 : a polyethylene terephthalate sheet having a thickness of 100 μm and a density of 1.6 g / cm ³ .

The thermal conductivity of K-1 of 0.18 W / mK was determined using a graph showing the relationship between the thermal conductivity of the foam and the cell rate (Plastic Data Handbook, p. 69, published by the Industrial Research Institute, 1980). Based on the thermal conductivity 0.21 W / mk at 300 K (27 ° C.) of unfoamed polypropylene at a density of 0.921 g / cm ³ (Plastic Data Handbook, p. 64, published by the Industrial Research Council in 1980). And a bubble ratio of 15% calculated from a foamed polypropylene density of 0.8 g / cm ³ .

When laminating a plastic sheet on a heat insulating substrate in K-2 and K-3, 25 parts by weight of a polyol (Takelac A36H, manufactured by Takeda Pharmaceutical Co., Ltd.) and polyisocyanate (Takenate A -7, manufactured by Takeda Pharmaceutical Co., Ltd.) 5 parts by weight of a solid content of 30% by weight of ethyl acetate urethane adhesive resin solution was applied to a dry film thickness of 1.5 μm, and dried at 80 ° C. for 1 minute. 2 kg / c at 80 ° C. so that the coated surface of the plastic sheet and the front or back surface of the heat insulating substrate overlap.
Laminating treatment was performed at m ² and 50 cm / min to form a plastic sheet on the heat insulating substrate.

Note that the material used for each of the above substrates is 300K
The thermal conductivity at (27 ° C.) is as follows. Art paper: 0.14W / mK (Chemical Handbook Basic Edition II Revised 4)
Edition, page 70, 1993, published by Maruzen) Polyethylene terephthalate: 0.29 W / mK (Plastic Data Handbook, page 67, 1980,
In the Table 1, the abbreviations in the column of the organic polymer substance represent the following.

Y1 : Phenoxy resin (PKH-J, manufactured by Union Carbide Co.) In Table 1, the abbreviations in the column of additives represent the following. T1 : Nitrocellulose Nitrification degree 12 (% by weight)
In Table 1, the abbreviation (S-
A, SB) are as follows. SA: Titanium monoxide: Titanium black 13M (manufactured by Mitsubishi Materials Corporation) SB:

[0086]

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Example 13 In Example 3, a hydrophilic layer composition was similarly coated on a substrate so as to have a dry film thickness of 7 μm, and then the following photosensitive layer composition was dried so as to have a dry film thickness of 1 μm. Was applied. 70 parts by weight of S-A described in Table 1-30 parts by weight of styrene-acrylate copolymer resin (John Grill J555 manufactured by Johnson Polymer Co.)-900 parts by weight of propylene glycol monomethyl ether acetate 900 parts by weight When evaluated in the same manner as in Example 3, the sensitivity was 20.
cm / s, the ink smearing property A of the non-image area was obtained.

[0088]

According to the present invention, it is possible to provide a direct-sensitive lithographic printing plate having high sensitivity and image reproducibility, and excellent in non-image area ink stain resistance.

Claims (4)

[Claims] 1. A direct photosensitive lithographic printing plate having at least a photosensitive layer containing a near-infrared light-to-heat converting substance and a hydrophilic layer on a substrate, wherein titanium oxide fine particles and / or zinc oxide fine particles are contained in the hydrophilic layer. A direct photosensitive lithographic printing plate characterized by being contained. 2. The total content of titanium oxide fine particles and zinc oxide fine particles is 30% by weight based on the total solid content in the hydrophilic layer.
The direct light-sensitive lithographic printing plate according to claim 1, wherein: 3. The direct photosensitive lithographic printing plate according to claim 1, wherein a photosensitive layer and a hydrophilic layer are provided on the substrate in this order. 4. The direct photosensitive lithographic printing plate according to claim 1, wherein a hydrophilic layer and a photosensitive layer are provided on the substrate in this order.