JPH11119413A - Direct photosensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct photosensitive lithographic printing plate high in sensitivity and image reproducibility and superior in ink receptivity in an image and the like. SOLUTION: In the direct photosensitive lithographic printing plate where the photosensitive layer containing a light absorber for 600-1300 nm wavelength lights and an organic polymer and a hydrophilic layer are formed in this order on a support, and the hydrophilic layer formed on the photosensitive layer contains the graft polymer of a hydrophilic acrylic monomer represented by the formula, in which each of R<1> and R<2> is H atom or an alkyl group; each of R<3> and R<6> is an alkylene or alkyleneoxy group or the like; each of R<4> and R<5> is H atom or a cellulose residue or the like; and each of (l) and (m) is 0, 1, 2, or 3.

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 capable of directly forming a lithographic printing plate by using a semiconductor laser or a light source capable of high-density light exposure according to the semiconductor laser from digital image data. More specifically,
The present invention relates to a direct photosensitive planographic printing plate having at least a photosensitive layer and a hydrophilic layer on a substrate in this order.

[0002]

2. Description of the Related Art In recent years, with the progress of digital image processing technology using a near-infrared semiconductor laser and a computer, a photosensitive lithographic plate has been directly used from digital image data formed on a computer without using a silver halide film for a printing plate. The printing plate is subjected to scanning exposure with a near-infrared semiconductor laser to insolubilize the exposed portion, and then an image is formed by an aqueous solution development process (wet development process) to make a plate, or the exposed portion is deteriorated, sublimated, melted and removed. Laser direct plate making technology, in which an image is formed by performing a dry development process to make a plate, has attracted 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 response to heat generated by ablation of the exposed portion of the photosensitive layer, the hydrophilic layer is simultaneously melted and removed by volatilization or combustion (Japanese Patent Application Laid-Open No. 7-314934, Japanese Patent Application Laid-Open No. 55-105560, 54-2603), (b) A transfer sheet having a photosensitive layer coated on a transparent support is superimposed on a printing plate substrate which has been subjected to a hydrophilic treatment so that the photosensitive layer and the hydrophilic surface are in contact with each other. After that, the substrate is exposed to a laser beam from the support side of the transfer sheet, and the photosensitive layer at the exposed portion is transferred to the substrate surface by ablation (Japanese Patent Laid-Open No. 50-102402). One which hydrophobic photosensitive layer of aqueous (JP 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.

However, in the conventional laser-direct photosensitive lithographic printing plate utilizing the ablation method (a), it is difficult to achieve both the strength and the removability of the hydrophilic layer. That is, when the strength of the hydrophilic layer is increased for the purpose of securing the printing durability, the removability tends to decrease, and accordingly, the sensitivity, the image reproducibility, and the ink receptivity of the image portion tend to decrease.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the sensitivity and image reproducibility of a hydrophilic layer by enhancing the removability of a hydrophilic layer by ablation, and to achieve a direct photosensitivity excellent in ink coverage of an image area. The plan is to provide a lithographic printing plate. 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]

As a result of various studies, the present inventors have found that such an object can be achieved by adding a specific polymer to the hydrophilic layer. That is,
The gist of the present invention is that at least 6
In a direct photosensitive lithographic printing plate in which a photosensitive layer containing a light absorber that absorbs light of 00 to 1300 nm and an organic polymer substance, and a hydrophilic layer are formed in this order,
Wherein the hydrophilic layer contains a hydrophilic acrylic polymer obtained by graft-polymerizing a hydrophilic acrylic monomer represented by the following general formula (I) formed on at least the surface of the photosensitive layer. Exists in photosensitive lithographic printing plates.

[0007]

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(Wherein R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a substituent, and R ³ and R ⁶ each independently represent And an alkylene group having 1 to 5 carbon atoms which may have a substituent,
An alkyleneoxy group or an alkyleneamino group;
⁴ and R ⁵ are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms which may have a substituent, a cellulose residue, HR ¹ C ＝ CR ² (R ⁶ ) _m C (O) C (R ³ ) _l
Shows an NH- group. Further, NR ⁴ R ⁵ may form a heterocyclic group together. l and m each independently represent an integer of 0 to 3. )

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred substrate used in the present invention has a flexibility that can be set in an ordinary lithographic printing machine,
There is no particular limitation as long as it can withstand the load applied during printing, but in addition to the function of the conventional substrate, heat generated by the energy of light absorbed by the photosensitive layer is transmitted to the substrate. Those having a function of preventing diffusion and enhancing the effect of ablation of the photosensitive layer and the hydrophilic layer are preferable. As described in detail below, the substrate 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. However, for the purpose of adding various functions, the base material may be used. And a reinforcing layer provided on the back surface of the ink and / or the ink-receiving layer provided on the photosensitive layer side surface (hereinafter, simply referred to as the front surface) (hereinafter, referred to as the front surface).
A composite substrate is also used.

[0010] 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 excellent heat insulation properties, that is, prevents heat diffusion. As the substrate used in the present invention, 300K (27
C) is preferably 0.2 W / mK or less, and more preferably 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 2.0 g / cm ³
Or less, more preferably 1.5 g / cm ³ or less. Specific examples of the substrate include papers such as high-quality paper, resin-treated paper, coated paper, art paper, photographic paper base paper, synthetic paper made from polypropylene and the like; wood board; polyethylene terephthalate sheet, polypropylene sheet, polyethylene Plastic sheets which may be foamed such as sheets, polystyrene sheets or foams thereof; metal plates such as aluminum plates and copper plates; dimensional stability of substrates, chemical resistance to solvents contained in ink, etc. sex,
From the viewpoint of heat insulation, coated paper, art paper, photographic printing paper base paper, resin-coated paper, synthetic paper, expanded polyethylene terephthalate sheet, expanded polypropylene sheet, expanded polyethylene sheet are preferred.

The thickness of the substrate is 10 μm to 3 mm, preferably 20 μm to 1 mm, and more preferably 50 μm to 500 μm.
μm. The photosensitive layer side (hereinafter referred to as the surface) of the substrate used in the present invention has an appropriate cushioning property in order to enhance the ink inking property of the image area of the photosensitive lithographic printing plate,
A composite substrate can be manufactured by providing an ink-receiving layer having high adhesion to an ink roller and having an effect of enhancing ink transferability.

[0013] Specific examples of the ink depositable layer include, for example, polyethylene terephthalate sheet, foamed polyethylene terephthalate sheet, polypropylene sheet, foamed polypropylene sheet, polyethylene sheet, foamed polyethylene sheet, and the like. It can be used by bonding to the surface.
Among these, a foamed polyethylene terephthalate sheet, a foamed polypropylene sheet, and a foamed polyethylene sheet having a density of 1.5 g / cm ³ or less are preferable because they have an effect of enhancing the heat insulating effect as well as the ink inking property. In addition, the durability of the printing plate is also improved by providing the ink deposition layer. The thickness of the ink deposition layer is 10 μm to 1 mm, preferably 20 μm to 100 μm, more preferably 20 μm to 75 μm.
μm.

Further, a reinforcing layer can be provided on the back surface of the substrate used in the present invention for the purpose of enhancing the durability of the printing plate. Examples of the reinforcing sheet used for providing the reinforcing layer include those used for the base material; those used for the ink deposition layer; metal plates such as aluminum plates, copper plates, and iron plates; aluminum foils and the like. 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
５００500 μm.

Further, in the present invention, it is also possible to produce a composite substrate having an ink deposition layer on the surface of the substrate and a reinforcing layer on the back surface. As described above, the base material, the ink-filling layer, and the reinforcing layer each have a main purpose of insulating effects, ink-filling properties, and durability, so that in order to improve the performance as a photosensitive printing plate, It is preferable to take advantage of the characteristics described above and to appropriately form a multilayer so as to compensate for the mutual shortage. For this reason, the same kind of material may be joined to a base material of a certain material as an ink-filling layer and / or a reinforcing layer, but in this case, each of the heat insulating effect, the ink-filling property, and the durability is satisfied. Therefore, a material of a grade suitable for the purpose may be appropriately selected. In the case of a composite substrate, it is needless to say that it is important that the thermal conductivity of the entire composite substrate is low, but in order to secure at least a heat insulating region, it is preferable that the base material itself is heat insulating. 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 50 μm to 500 μm thick art paper, a high quality paper, a resin processed paper, a synthetic paper or a coated paper, and a 20 μm thick ink depositing layer Laminated polyethylene terephthalate sheet, foamed polyethylene terephthalate sheet, polypropylene sheet, foamed polypropylene sheet, polyethylene sheet, or foamed polyethylene sheet of up to 75 μm. Further, on the back surface of the composite substrate, a reinforcing layer of the same type as the ink
A three-layer structure obtained by laminating an aluminum plate having a thickness of up to 500 μm is exemplified.

When laminating an ink-fillable sheet or a reinforcing sheet on a substrate, one or both of the two sheet surfaces to be laminated can be laminated, for example, as disclosed in
After applying an adhesive such as urethane resin described in Japanese Patent No. 225087 to a thickness of 0.1 to 10 μm,
It is preferable to laminate at a temperature of 0.1 to 50 kg / cm ² and 0.1 to 50 m / s to form an ink deposition layer or a reinforcing layer on the substrate.

A photosensitive layer is formed on the surface of the substrate.
The photosensitive layer is formed by applying a coating solution obtained by dissolving or dispersing a light absorbing agent, an organic polymer substance, and other additives as necessary using an appropriate solvent, onto the substrate surface (the upper surface of the inking layer). It is formed by doing. The light absorber used in the present invention efficiently absorbs light of 600 to 1300 nm,
The conversion to heat causes the ablation of the photosensitive layer to remove the photosensitive layer, while at the same time inducing the ablation of the hydrophilic layer in response to the resulting heat, melting, volatilizing or burning, and / or It has a function of removing the hydrophilic layer by the pressure at the time of ablation of the layer.

The light absorbing agent can be used without any particular limitation as long as it has a function of absorbing light of 600 to 1300 nm and converting light energy into heat energy. And inorganic pigments, organic pigments, metals and the like. Specifically, for example, carbon black (MA-7, a product of Mitsubishi Chemical Corporation,
MA-100, MA-220, # 5, # 10, color black FW2, FW20, PRINTEX V, etc., products of Degussa); graphite; metals such as titanium and chromium;
Titanium oxide (Titanium Black 13 manufactured by Mitsubishi Materials Corporation)
M), metal oxides such as 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; Black, such as black pigments such as Lionol Green 2YS and Green Pigment 7,
Organic pigments such as green are used. In addition, "special functional dyes" (edited by Ikemori and Sumiya, published by CMC Co., Ltd. in 1986), "chemistry of functional dyes" (edited by Higaki, published by CMC Co., Ltd. in 1981), "Dye Handbook" (Okawa) , Edited by Hirashima, Matsuoka, Kitao, published by Kodansha), a catalog published in 1995 by Japan Photographic Dye Laboratories, Inc. and E
xciton Inc. And dyes having absorption in the near-infrared region described in Laser Dye Catalog published in 1989. Such as 600-1300
Some dyes having absorption in the wavelength region of nm are exemplified in Table 1 below.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

[0024]

[Table 5]

[0025]

[Table 6]

[0026]

[Table 7]

[0027]

[Table 8]

[0028]

[Table 9]

[0029]

[Table 10]

[0030]

[Table 11]

[0031]

[Table 12]

[0032]

[Table 13]

[0033]

[Table 14]

[0034]

[Table 15]

[0035] (in Table 1, -X ¹ is, Br ^{-, I -,} C
_{^{l -, ClO 4 -, BF}} 4 -,

[0036]

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Represents the following. Of these, particularly preferred dyes are those having a wavelength range of 650 to 13
At 00 nm, a cyanine dye represented by the following general formula [A], a polymethine dye represented by the following general formula [B], and a pyrylium dye or a thiopyrylium dye represented by the following general formula [C].

[0038]

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[Wherein, R^1a, R^2aHas a substituent
Good C₈The following alkyl groups, wherein the substituents are
Nyl group, phenoxy group, alkoxy group, sulfonic acid group,
A carboxyl group; Q¹May have a substituent
Heptamethine group, wherein the substituent is C₈The following al
A kill group, a halogen atom, an amino group,
The tin group is bonded to the substituents on the two methine carbons
Optionally formed cyclohexene formed by
May contain a ring or a cyclopentene ring
And the substituent is C₆The following alkyl groups or halogen sources
Child; m¹, M ^TwoIs each 0 or 1;
Z¹, Z^TwoIs a group of atoms necessary to form a nitrogen-containing heterocyclic ring.
Yes; X^-Represents a counter anion. ]

[0040]

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[Wherein, R ^{3b to} R ^6b are an alkyl group of C ₈ or less; Z ⁴ and Z ⁵ are an aryl group which may have a substituent, wherein the aryl group is a phenyl group, naphthyl group, a furyl group or a thienyl group, the substituents C ₄
An alkyl group, a dialkylamino group having a C ₈ an alkyl group, a C ₈ an alkoxy group and a halogen atom. Q ² represents a trimethine group or a pentamethine group; X ⁻ represents a counter anion. ]

[0042]

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Wherein Y ¹ and Y ² are oxygen or sulfur atoms; R ^7c , R ^8c , R ^15c and R ^16c are a phenyl or naphthyl group which may have a substituent; or R ^9c to R ^14c represents a hydrogen atom or a C ₈ an alkyl group; is an C ₈ an alkyl group or a C ₈ an alkoxy group; l ¹ and l ² each independently represents 0 or 1 Alternatively, R ^9c and R ^10c , R ^11c and R ^12c or R ^13c and R ^14c are mutually bonded

[0044]

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(Provided that R ^{17c to} R ^19c represent a hydrogen atom or C
₆ is an alkyl group, n ^c is 0 or 1. And Z ³ represents a halogen atom or a hydrogen atom, and X ⁻ represents a counter anion. Specific examples of the counter anion X ^{− in the above} formulas [A], [B] and [C] include, for example, Cl ⁻ , Br ⁻ , I
_{^{-, ClO 4 -, BF 4}} -, PF 6 - inorganic acid anion, benzenesulfonic acid, p- toluenesulfonic acid and the like, naphthalene-1-sulfonic acid, acetic acid, and the like anions of organic acids such as organic boric acid Can be.

Further, a dye whose counter ion is an organic borate anion of the following general formula (D) is preferable because of its excellent solubility in a coating solvent.

[0047]

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(Wherein R ^{1d to} R ^4d each represent a C _{1 to} C ₁₅ alkyl group which may have a substituent, a C _{6 to} C ₁₅ aryl group which may have a substituent, And represents a C _{4 to} C ₁₅ aromatic heterocyclic group which may have a substituent.) Specific examples of the organic borate ion include

[0049]

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And the like. These light absorbers are used alone or as a mixture of two or more, and are dissolved or dispersed in a photosensitive layer coating solution. The blending ratio of the light absorbing agent in the photosensitive layer is 5 to 100% by weight of the solid content of the entire photosensitive layer,
Preferably 10 to 98% by weight, more preferably 20 to 9% by weight.
5% by weight. If the blending ratio of the light absorber is extremely low, the light cannot be sufficiently absorbed, and the ablation effect tends to decrease. In this case, 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.

The organic polymer substance contained in the photosensitive layer used in the present invention is used for the purpose of enhancing the coating properties, the film strength in the photosensitive layer, and the effect of ablation. Those with excellent solubility are selected. Examples of the organic polymer substance include unsaturated acids such as (meth) acrylic acid and itaconic acid, alkyl (meth) acrylate, and (meth) acrylic acid.
Copolymers with phenyl acrylate, benzyl (meth) acrylate, styrene, α-methylstyrene, etc .; alkyl methacrylate and alkyl acrylate polymers represented by polymethyl methacrylate; alkyl (meth) acrylate and acrylonitrile Copolymers of acrylonitrile with vinyl chloride or vinylidene chloride; modified cellulose having a carboxyl group in the side chain; polyethylene oxide; polyvinylpyrrolidone; phenol, o-, m-,
Novolak resin obtained by condensation reaction of p-cresol and / or xylenol with aldehyde, acetone, etc .; polyether of epichlorohydrin and bisphenol A; soluble nylon; polyvinylidene chloride; chlorinated polyolefin; vinyl chloride and acetic acid Copolymer with vinyl; polymer with vinyl acetate; copolymer with acrylonitrile and styrene; copolymer with acrylonitrile, butadiene and styrene; polyvinyl alkyl ether; polyvinyl alkyl ketone; polystyrene;
Polyethylene terephthalate isophthalate; acetyl cellulose; acetyl propoxycellulose; acetyl butoxycellulose; nitrocellulose; celluloid; The compounding ratio of the organic polymer substance in the photosensitive layer is from 5 to 95% by weight, preferably from 10 to 90% by weight, more preferably from 20 to 80% by weight of the total solids of the photosensitive layer.

In the above-mentioned photosensitive layer, various additives having a hydrophobic group, for example, p-octylphenol / formalin novolak resin, for the purpose of enhancing the adhesion of 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. A sulfonyl hydrazide compound such as a nitroso compound, p-toluenesulfonylhydrazine, p, p'-oxybis (benzenesulfohydrazine) or the like is used in an amount of 0 to 70% by weight, preferably 5 to 60% by weight based on the total solid content of the photosensitive layer; More preferably, 10
６０60% by weight can be used.

Nitrocellulose, which will be described below, is preferably used as an organic polymer substance that enhances the ablation effect. Such nitrocellulose is decomposed by the heat generated by absorbing the near-infrared laser light by the light absorber and efficiently generating a low-molecular gas, whereby the hydrophilic layer provided on the photosensitive layer is formed. And has a function of promoting removal of the laser exposed portion.

Nitrocellulose is obtained by subjecting natural cellulose purified by a conventional method to nitric acid esterification with a mixed acid, and introducing some or all of the nitro group into the three hydroxyl groups present on the glucopyranose ring, which is a constituent unit of cellulose. It is obtained by doing. 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 polymerization degree of nitrocellulose is 20 to
200, preferably 25-150. If the degree of polymerization is extremely high, the removal of the hydrophilic 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 blending ratio of nitrocellulose in the photosensitive layer is from 0 to 80% by weight, preferably from 5 to 70% by weight, more preferably from 30 to 70% by weight, based on the total solid components of the photosensitive layer.
% 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 fountain solution supplied at the time of printing. And a function to prevent lipophilic ink particles from adhering and form a non-image portion on printed matter. The hydrophilic layer of the present invention contains a hydrophilic acrylic polymer having a function of absorbing dampening water and forming a thin film of water on the hydrophilic layer. In order to prevent the hydrophilic acrylic polymer from being peeled off from the surface of the photosensitive layer during printing, the hydrophilic acrylic polymer is treated with a polymerization initiator which generates radicals by light or heat to form a hydrophilic acrylic monomer. It is preferable to form the polymer by applying and curing with light or heat after coating. That is, by light irradiation or heating, hydrogen atoms on the surface of the photosensitive layer are extracted, and an acrylic graft polymer is formed by addition polymerization of radicals and acrylic monomers generated on the photosensitive layer, which forms the hydrophilic layer. It exhibits the function of firmly fixing to the photosensitive layer. Regarding this graft polymerization and its mechanism,
S. Tazuke and H.S. Kimura, J. et al. P
olym. Sci. Lett. Ed. 16,497 (1
978); Makromol. Chem. 179,26
03 (1978); Polym. Sci. Let
t. Ed. 15, 2702 (1977).

The hydrophilic acrylic monomers used for the graft polymerization of the present invention include those represented by the above general formula (I). In the general formula (I), R ¹ and R ²
Represents a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group, and is preferably a hydrogen atom or a methyl group. R ³ or R ⁶ is a linear or branched alkylene group having 1 to 5 carbon atoms such as a methylene group, an ethylene group, a propylene group, an isobutylene group, a butylene group, a pentylene group, or an alkyleneoxy group corresponding to the alkylene group; , An alkyleneamino group. R ⁴ and R ⁵ are hydrogen atoms, and have 1 carbon atom as described above.
To 5 alkyl groups. Examples of the substituent in these groups include a hydroxyl group, a carboxyl group, and a sulfonic acid. When NR ⁴ R ⁵ forms a heterocyclic group, a heterocyclic ring which may contain an oxygen atom or a sulfur atom such as pyridyl, morpholino and thiomorpholino is exemplified. Specific examples of the hydrophilic acrylic monomer represented by the general formula (I) are shown below.

[0058]

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(Acrylamidomethyl) cellulose acetate
butyrate weight average molecular weight (Mw) 10,000, acetyl
12.8% by weight, butyryl 38.9% by weight, acrylamido
0.6% by weight of methyl, 1.4% by weight of hydroxyl, ・ (Acrylamidomethyl) cellulose acetate propionate
(Mw) 20,000, acetyl 0.5% by weight, propionyl
42.0% by weight, acrylamidomethyl 3.0% by weight, hydr
3.2% by weight of oxyl,

Known polymerization initiators for generating radicals from these hydrophilic acrylic monomers by light or heat include, for example, Shinzo Yamashita and Tosuke Kaneko, "Handbook of Crosslinking Agents," Taiseisha Publishing Co. (1981). , "UV Curing System" by Kiyomi Kato, published by Sogo Gijutsu Center (1989), "UV.EB Curing Handbook (Raw Materials)" by Kiyomi Kato, Polymer Publishing Association (1985), supervised by Kiyoshi Akamatsu, "New photosensitive resin Practical techniques ", CMC, pp. 102-14 (1987) and the like.
Specifically, as the photopolymerization initiator, for example, benzophenone, Michler's ketone, fine chemical, 199
Vol. 1, No. 1, March 1, 1 issue. 4, pages 16-26
Dialkyl acetophenone type, benzyl dialkyl ketal type, benzoin alkyl ether type, thioxanthone derivative, acyl phosphine oxide type, etc.
In addition, JP-A-58-40302, JP-B-45-40302
No. 37377, hexaarylbiimidazoles, s-trihalomethyltriazines, and JP-A-59-377.
And titanocenes described in JP-B-152396.

Examples of the photopolymerization initiation system sensitive to visible light of ultraviolet to 550 nm include, for example, a system of hexaarylbiimidazole, a radical generator and a dye (JP-B-45).
JP-A-37377), a system of hexaarylbiimidazole and (p-dialkylaminobenzylidene) ketone (JP-A-47-2528, JP-A-54-155292).
JP-A-48-15184, a system of a cyclic cis-α-dicarbonyl compound and a dye (JP-A-48-84183), and a system of a substituted triazine and a merocyanine dye (JP-A-54-151024).
JP-A-52-1), a system of ketocoumarin and an activator (JP-A-52-1)
12681, JP-A-58-15503, JP-A-60-15
-88005), a system of a substituted triazine and a sensitizer (JP-A-58-29803, JP-A-58-40302).
JP-A-59-56403), a system of biimidazole, styrene derivative, and thiol (JP-A-59-56403), a sensitizer containing a dialkylaminophenyl group and a biimidazole (JP-A-2-69, JP-A-57-57). 168880, JP-A-5-107761, JP-A-5-210240,
JP-A-4-288818).

Examples of the polymerization initiator which generates a radical by heat include a combination of an organic peroxide such as benzoyl peroxide and cumene hydroperoxide with an amine such as N, N-dimethylaniline, tetrahydroquinoline and triethylamine. A combination of hydrogen peroxide and iron (II) sulfate,
Examples include a combination of potassium persulfate and triethanolamine. The amount of these is from 10 to 99 relative to the total solids forming the hydrophilic layer.
% By weight, preferably 30 to 98% by weight, more preferably 50 to 95% by weight, and the polymerization initiator is 0.1 to 30% by weight.
%, Preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight.

The hydrophilic layer of the present invention may contain a hydrophilic binder polymer other than the above-mentioned hydrophilic acrylic graft polymer, if necessary, for the purpose of improving the printing durability of the non-image portion. Can be done. The hydrophilic binder polymer is a carboxyl group, an amino group, a phosphoric acid group, a sulfonic acid group, or a salt, a hydroxyl group, an amide group, or a carboxyl group, an amino group, a phosphoric acid group, or a side chain of a polymer composed of carbon-carbon bonds.
One or more hydrophilic functional groups such as polyoxyethylene groups and the like, or a networked polymer containing a plurality thereof, or a carbon atom, one of carbon-carbon bonds is at least one or more of oxygen, nitrogen, sulfur, and phosphorus. One kind of a hydrophilic functional group such as a carboxyl group, an amino group, a phosphoric acid group, a sulfonic acid group, or a salt, a hydroxyl group, an amide group, or a polyoxyethylene group on a polymer or a side chain thereof, which is linked by a hetero atom These are polymers containing a plurality of the above, specifically, poly (meth) acrylate, polyoxyalkylene, polyurethane, epoxy ring-opening addition polymerization, poly (meth) acrylic acid, poly (meth) acrylamide Examples include polymers based on polyesters, polyesters, polyamides, polyamines, polyvinyls, polysaccharides or cellulose derivatives. Come. Among them, 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,
Those having any one of amide groups or a combination thereof, and those having a polyoxyethylene group overlapped with a part of the hydrophilic functional group and 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, and 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 together with an isocyanate compound or a blocked polyisocyanate compound and other components described later to the above active hydrogen-free solvent 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 Sorbitol and the like, and 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 utilized by utilizing the hydroxyl groups contained therein, and the above-mentioned functional groups capable of undergoing a cross-linking reaction. 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 cross-linked three-dimensionally by heating, or a water-soluble colloid-forming compound such as casein, glue or gelatin is cross-linked three-dimensionally by heating to form a network structure. 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 bis anhydro trimellitate, glycerol tris anhydro trimellitate, 1,3,3
a, 4,5,9b hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2
-C] furan-1,3-dione, 3,3 ', 4,4'-
Diphenylsulfonetetracarboxylic dianhydride, 1,
2,3,4-butanetetracarboxylic dianhydride can be exemplified.

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 also be 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.

At the time of handling before and after the formation of the hydrophilic layer, it may be preferable to block (mask) the isocyanate group by a known method in order to prevent the isocyanate group from changing. For example, "Plastic Materials Course Polyurethane Resin" by Keiji Iwata, published by Nikkan Kogyo Shimbun (1974), pp. 51-52, "Polyurethane Resin Handbook" by Keiji Iwata, published by Nikkan Kogyo Shimbun (19)
87), 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. Preferably, 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 be brittle, and if it is longer than 50,000, it may be unfavorable because it swells with fountain solution and printing durability is impaired. 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 compounding ratio of these hydrophilic binder polymers is 0 to 80% by weight, preferably 0 to 7% by weight, based on the total solid content of the hydrophilic layer.
0% by weight, more preferably 0 to 60% by weight. In the hydrophilic layer of the present invention, the following monofunctional monomer or polyfunctional monomer may be used in combination with the acrylic monomer represented by the general formula (bb), if necessary.

Specifically, vinyl pyridine, N-vinyl-2-pyrrolidone, p-styrenesulfonic acid or a salt thereof, methoxytriethylene glycol (meth) acrylate, methoxytetraethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) ) Acrylate (number average molecular weight of PEG 400), methoxypolyethylene glycol (meth) acrylate (PEG
Number average molecular weight of 1000), butoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate,
Phenoxydiethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, nonylphenoxyethyl (meth) acrylate, dimethyloltricyclodecanedi (meth) acrylate, polyethylene glycol di (meth) acrylate (number average molecular weight of PEG 400), Polyethylene glycol di (meth) acrylate (number average molecular weight of PEG 6
00), polyethylene glycol di (meth) acrylate (number average molecular weight of PEG 1000), polypropylene glycol di (meth) acrylate (number average molecular weight of PEG 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. These monomers have the general formula (b)
0 to 50% by weight, preferably 0% by weight of the acrylic compound of b)
-30% by weight, and more preferably 0-15% by weight.

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 80% by weight, preferably 0 to 70% by weight based on the solid content.

The thickness of the hydrophilic layer in the present invention is 0.1
To 100 μm, preferably 0.2 to 50 μm, and more preferably 0.5 to 20 μm. The direct photosensitive printing plate provided with the photosensitive layer and the hydrophilic layer on the substrate according to the present invention is a semiconductor laser light that oscillates light of 600 to 1300 nm or a light source equivalent thereto, such as a xenon flash or a light emitting diode. Focus the light, 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
Scanning exposure is performed by ^two or more beam spots, 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, the hydrophilic layer surface may be subjected to a post-treatment for 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 as needed.

As another method for removing the fine particles generated by the ablation, a cover sheet having a surface having a higher adhesiveness to the fine particles than the hydrophilic layer is exposed to the hydrophilic layer of the photosensitive printing plate. 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 for removing fine particles on the hydrophilic layer. As the cover sheet, polyethylene terephthalate, polypropylene, polycarbonate, on a substrate such as paper, silicone rubber, ionomer,
One provided with an adhesive layer such as vinyl acetate as needed.

[0082]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In addition, it is as follows under the board | substrate used in the Example and the light absorber.

(Substrate) K1: 35 μm thick, 1.2 density on both sides of art paper (heat insulating base material) having a thickness of 100 μm and a density of 1.1 g / cm ^3.
g / cm ³ composite substrate laminated with an expandable polyethylene terephthalate sheet. K2: a polyethylene terephthalate sheet having a thickness of 100 μm and a density of 1.6 g / cm ³ K3: an aluminum plate having a thickness of 300 μm and a density of 2.7 g / cm ³ K4: a foamed polypropylene sheet having a thickness of 140 μm and a density of 0.8 g / cm ³ (Oji Yuka Synthetic Paper, GWG) K5: Expanded polypropylene sheet with a thickness of 130 μm and density of 0.8 g / cm ³ (Oji Yuka Synthetic Paper, GWG) K6: Thick on the back of the K3 expanded polypropylene sheet Composite substrate laminated with an aluminum plate having a thickness of 0.2 mm and a density of 2.7 g / cm ³

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,
(Issued by the Industrial Research Committee) Aluminum plate: 237W / mK (Chemical Handbook Basic Edition II Rev. 4)
Edition, p. 68, 1993, published by Maruzen) Foamed polypropylene: 0.18 W / mK (Relationship graph between thermal conductivity and cell rate of foam (Plastic Data Handbook, p. 69, 1980, published by the Industrial Research Council) ), The thermal conductivity of unfoamed polypropylene at a density of 0.921 g / cm ³ at 300 K (27 ° C.) 0.21 W / mK (Plastic Data Handbook,
(Page 64, published by the Industrial Research Institute, 1980). The foam ratio was calculated from the foam ratio of 15% calculated from the density of foamed polypropylene of 0.8 g / cm ³ . )

When laminating a plastic sheet or an aluminum plate described in K1 and K6 on a heat insulating substrate, 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.) An ethyl acetate urethane adhesive resin solution consisting of 5 parts by weight and having a solid content of 30% by weight was applied to a dry film thickness of 1.5 μm, dried at 80 ° C. for 1 minute, and dried. 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.

(Light Absorbing Agent)

[0087]

Embedded image

Examples 1 to 8 and Comparative Example 1 The following photosensitive compositions were applied on the substrates shown in Table 2.
After coating, the coating was dried at 85 ° C. for 3 minutes to provide a photosensitive layer having a dry film thickness of 2 μm. Subsequently, the following hydrophilic layer composition was applied on the photosensitive layer in a coating liquid film thickness of 30 μm. Next, the coated surface was irradiated with light for 3 minutes at an exposure distance of 60 cm using a 3 kW high-pressure mercury lamp, washed with water to remove unreacted acrylamide and its homopolymer, dried at 80 ° C. for 2 minutes, and dried to a thickness of 1 μm. A hydrophilic layer was formed.

(Photosensitive layer composition) Light absorber: Compound (listed in Table 2) 50 parts by weight Organic polymer substance 1: Phenoxy resin (PKH-J, manufactured by Union Carbide) 50 parts by weight Organic polymer substance 2: Nitrocellulose; degree of nitrification 12 (% by weight), average polymerization degree 40 Compounding amount shown in Table 2 Coating solvent: 900 parts by weight of cyclohexanone

(Hydrophilic layer composition) Acrylamide 100 parts by weight Photopolymerization initiator (benzophenone) 5 parts by weight Thickener (hydroxyethyl cellulose; Tylose H300, manufactured by Hoechst) 6 parts by weight Surfactant (polyethylene glycol alkylphenyl) Ether; manufactured by Kao Corporation, Emulgen 911), 10 parts by weight Coating solvent water 195 parts by weight Ethanol 75 parts by weight Isobutyl alcohol 25 parts by weight Diethanolamine 32.5 parts by weight

The obtained photosensitive printing plate was subjected to an 830 nm semiconductor laser lithographic printing plate exposure apparatus (Creo's
Using d setter 3244T), a halftone image of 220 lines with 3 to 97% was image-exposed at various exposure amounts. By this laser exposure, the photosensitive layer that absorbed the laser light was ablated and removed together with the upper hydrophilic layer, forming a 3-97% positive-like hydrophilic layer halftone dot image. This was evaluated for the sensitivity and the ink inking property according to the following criteria.

(Sensitivity) The halftone dot images of the hydrophilic layer at various exposure amounts were observed with a microscope of 400 times, and the sensitivity was evaluated based on the minimum exposure amount at which the 97% hydrophilic halftone dot image was reproduced. The lower the exposure, the higher the sensitivity.

(Ink Ink Filling Property) Five times of coating was performed on a printing plate subjected to laser exposure at the minimum exposure amount using a sponge to which a developing ink (Developing Ink PI-2 manufactured by Fuji Photo Film Co., Ltd.) was applied. After the treatment, the ink depositing property was evaluated from the ink depositing state of the halftone dot image portion of 50% of the printing plate. A: Ink adheres to 80% or more of the halftone dot image portion. B: Ink adheres to 70% or more and less than 80% of the halftone dot image portion. C: Ink adheres to a portion of 40% or more and less than 70% of a halftone dot image portion. D: The portion where the ink adheres is less than 40% of the halftone dot image portion.

Comparative Example 1 The following composition was used in place of the hydrophilic composition used in the example. After coating, the composition was dried at 100 ° C. for 4 minutes to provide a hydrophilic layer having a dry film thickness of 1.5 μm. Except for the above, a photosensitive printing plate was prepared in the same manner as in the examples, and evaluated in the same manner.

(Hydrophilic Layer Composition of Comparative Example) Polyvinyl alcohol (GL-05, manufactured by Nippon Synthetic Chemical Co., Ltd.) 100 parts by weight Water 900 parts by weight The results of the examples and comparative examples are shown in Table 2.

[0096]

[Table 16]

[0097]

According to the present invention, a direct photosensitive lithographic printing plate having excellent sensitivity and inking property can be obtained by including a graft polymer of a water-soluble acrylic compound such as acrylamide in a hydrophilic layer. Can be In particular, by using a substrate having a low thermal conductivity, a printing plate having higher sensitivity can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03F 7/027 503 G03F 7/027 503

Claims (10)

[Claims] 1. The method according to claim 1, wherein at least 60
In a direct photosensitive lithographic printing plate in which a photosensitive layer containing a light absorbing agent that absorbs light of 0 to 1300 nm and an organic polymer substance, and a hydrophilic layer are formed in this order, the hydrophilic layer is at least photosensitive. A direct photosensitive lithographic printing plate comprising a hydrophilic acrylic polymer formed by graft-polymerizing a hydrophilic acrylic monomer represented by the following general formula (I) formed on the surface of a hydrophilic layer. Embedded image (Wherein, R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms which may have a substituent, and R ³ and R ⁶ each independently represent which may have a substituent alkylene group having 1 to 5 carbon atoms, it shows an alkylene group or alkylene amino groups, R ^4, R ⁵ is
Each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms which may have a substituent, a cellulose residue, HR ¹ C
ＣＲCR ² (R ⁶ ) _m C (O) C (R ³ ) ₁ NH— Further, NR ⁴ R ⁵ may form a heterocyclic group together. l and m are each independently 0 to 3
Indicates an integer. ) 2. The direct photosensitive lithographic printing plate according to claim 1, wherein the light absorbing agent is an organic borate dye. 3. The thermal conductivity of a substrate constituting a substrate is 0.2.
3. The direct-sensitive lithographic printing plate according to claim 1, wherein the lithographic printing plate is not more than W / mK. 4. The lithographic printing plate of claim 3, wherein the density of the substrate is 2.0 g / cm ³ or less. 5. The substrate according to claim 1, wherein the substrate comprises the base material and an ink deposition layer provided on the surface of the base material (the photosensitive layer side). Direct photosensitive lithographic printing plate. 6. The direct photosensitive lithographic printing plate according to claim 5, wherein the ink deposition layer is made of a foamed plastic. 7. The direct photosensitive lithographic printing plate according to claim 6, wherein the foamed plastic is foamed polyethylene terephthalate, foamed polypropylene or foamed polyethylene. 8. The density of the ink deposition layer is 1.5 g / cm.
8. The direct-sensitive lithographic printing plate according to claim 5, wherein the ratio is ³ or less. 9. The direct photosensitive lithographic printing plate according to claim 1, wherein a reinforcing layer is provided on the back surface of the substrate. 10. The direct photosensitive lithographic printing plate according to claim 1, wherein the photosensitive layer contains nitrocellulose having a nitrification degree of 2 to 13 and an average polymerization degree of 20 to 200. .