JPH0522228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a lithographic plate material, particularly a lithographic plate material sensitive to visible light, and the efficient production of a lithographic printing plate using the same.

[Prior Art] A lithographic printing plate is a plate in which an image area and a non-image area are formed on the same plane on a thin substrate generally having a thickness of 0.1 to 0.5 mm. The image area requires lipophilicity and water repellency, and the non-image area requires hydrophilicity, water retention, and ink repulsion. Various materials are known for forming the image area and the non-image area, but currently the non-image area is made of metal plates such as aluminum or zinc,
The image area consists of an organic photosensitive layer made of diazonium salts, quinonediazides, etc., and is commercially available as a PS plate (a plate material pre-coated with a photosensitive layer).

[Problems to be solved by the invention] With the development of such PS plates, significant labor savings in printing work are being achieved, but there is a desire for the emergence of image forming technology that does not require negatives to further save labor. has been done. In order to develop such technology, an image forming method in which images are drawn directly onto the plate material using a laser beam is considered, and the laser light source to be used is less expensive than a laser light source that emits light in the ultraviolet region due to equipment and energy costs. It is necessary to use a laser light source that emits light in the visible range, such as an argon ion laser. However, currently commercially available PS plates use diazonium salts and quinonediazides, which are hardly sensitive to visible light, and are therefore unsuitable for realizing such technology. It was hoped that the material would be developed.

[Means for Solving the Problems] As a result of various studies conducted by the present inventors in order to meet the above-mentioned needs, the present inventors have found that certain types of photopolymerization initiation systems can be used for addition-polymerizable compounds having ethylenically unsaturated double bonds. It has been discovered that a composition containing a xanthene or thioxanthene dye exhibits excellent photosensitivity to visible light, and that the cured polymer resin has excellent physical properties for printing. It has also been found that when a peroxide is blended with the xanthene or thioxanthene dye, the printing durability of the obtained plate material is extremely good. The present invention was completed based on these findings.

The gist of the present invention is to provide a support having a hydrophilic surface, an addition-polymerizable compound having an ethylenically unsaturated double bond provided on the surface, and a compound having the formula: [In the formula, A is an oxygen atom or a sulfur atom, ) is a double bond, and if Y is a nitrogen atom, the bond with the adjacent carbon atom is a single bond.), Z is the oxygen atom (in this case, the bond with the adjacent carbon atom is a double bond). ), lower alkoxy group or lower alkanoyloxy group, R ¹ is lower alkyl group, hydroxy lower alkyl group, lower alkoxy lower alkyl group, di-lower alkylamino lower alkyl group or aryl group, R ² is lower alkoxy or di-lower alkylamino group. In addition, Z and
R ¹ is both −Z−R ¹ −, It may also represent ] Characterized by a photopolymerization initiation system containing a xanthene or thioxanthene dye shown as an essential component and a photosensitive resin layer containing a peroxide, it is sensitized to visible light and has good printing durability. It consists in a lithographic plate material that provides a lithographic printing plate.

[Function] There are no particular restrictions on the support as long as the surface shows hydrophilicity and shows good adhesion to the photosensitive resin layer, but usually aluminum, zinc, nickel, stainless steel, etc. are used. A metal plate is used.

The photosensitive resin layer provided on the hydrophilic surface of the support contains as essential components an addition polymerizable compound having an ethylenically unsaturated double bond (hereinafter referred to as "double bond-containing compound") and a photopolymerization initiation system. Contains.

A double bond-containing compound is a monomer having an ethylenically unsaturated double bond that undergoes addition polymerization and curing due to the action of a photopolymerization initiation system, resulting in substantial insolubilization, or a monomer containing ethylene in the side chain or main chain. It is a polymer with sexually unsaturated double bonds, and is generally heated at 100℃.
Those having a boiling point higher than that are preferred. Specific examples include unsaturated carboxylic acids, esters of unsaturated carboxylic acids and aliphatic polyhydroxy compounds, esters of unsaturated carboxylic acids and aromatic polyhydroxy compounds, unsaturated carboxylic acids and polycarboxylic acids, and aliphatic polyhydroxy compounds. Examples include esters obtained by esterification reaction with polyhydric hydroxy compounds such as group polyhydroxy compounds and aromatic polyhydroxy compounds.

Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, and maleic acid. Aliphatic polyhydroxy compounds include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, propylene glycol, dihydric alcohols such as 1,2-butanediol, trimethylolethane, trimethylolpropane, glycerol, etc. Examples include trihydric alcohols, alcohols of tetrahydric or higher valence such as pentaerythritol and tripentaerythritol, and polyhydric hydroxycarboxylic acids such as dihydroxymaleic acid. Examples of aromatic polyhydroxy compounds include hydroquinone, resorcinol, catechol, and pyrogallol. Examples of polyhydric carboxylic acids include phthalic acid, isophthalic acid, terephthalic acid,
Examples include tetrachlorophthalic acid, trimellitic acid, pyromellitic acid, benzophenone dicarboxylic acid, maleic acid, fumaric acid, malonic acid, glutaric acid, adipic acid, sebacic acid, and tetrahydrophthalic acid.

Specific examples of esters of aliphatic polyhydroxy compounds and unsaturated carboxylic acids include ethylene glycol diacrylate, triethylene glycol diacrylate, tetramethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and pentaerythritol. Acrylic acid esters such as diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tripentaerythritol octaacrylate, glycerol diacrylate, triethylene glycol diacrylate, etc. Methacrylate, tetramethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, dipentaerythritol dimethacrylate,
dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate, tripentaerythritol octamethacrylate,
Ethylene glycol dimethacrylate, 1,2-
Methacrylic acid esters such as butanediol dimethacrylate and sorbitol tetramethacrylate, ethylene glycol diitaconate, propylene glycol diitaconate, 1,2-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol triitaconate, etc. Crotonate esters such as itaconic acid ester, ethylene glycol dicrotonate, diethylene glycol dicrotonate, and pentaerythritol tetracrotonate, maleic acid esters such as ethylene glycol dimaleate, triethylene glycol dimaleate, and pentaerythritol dimaleate. be. Examples of esters of aromatic polyhydroxy compounds and unsaturated carboxylic acids include hydroquinone diacrylate, hydroquinone dimethacrylate, resorcin diacrylate, resorcin dimethacrylate, and pyrogallol triacrylate. The esters obtained by the esterification reaction of unsaturated carboxylic acids with polyhydric carboxylic acids and polyhydric hydroxy compounds are not necessarily single products, but typical examples are shown below (however, Z′ is an acryloyl group or methacryloyl group): Z' _{- OC2H4} -OOC- _{C6H4 -} COO-C2H4O-Z'Z' ₍ - _OC2H4 ) _{-2 OOC ( -CH2} )- ₄ COO( _{-C2H4O ) -2}
Z′ Z′(−OC ₂ H ₄ )− ₃ OOC−CH=CH−COO(−C ₂ H ₄ O
) − ₃ Z′ Z−OC ₂ H ₄ −OOC−C ₆ H ₄ −COO−C ₂ H ₄ −OH Other examples of double bond-containing compounds used in the present invention include acrylamide, acrylamides such as ethylenebisacrylamide and hexamethylenebismethacrylamide, methacrylamides such as ethylenebismethacrylamide and hexamethylenebismethacrylamide, diallyl phthalate, Examples include allyl esters such as diallyl malonate, diallyl fumarate, and triallyl isocyanurate, and vinyl-containing compounds such as divinyl adipate, divinyl phthalate, and ethylene glycol divinyl ether.

Polymers having ethylenically unsaturated bonds in the main chain include, for example, polyesters obtained by a polycondensation reaction of unsaturated dihydric carboxylic acids and dihydroxy compounds;
Examples include polyamides obtained by a polycondensation reaction of unsaturated dihydric carboxylic acids and diamines. Examples of unsaturated dihydric carboxylic acids include maleic acid and fumaric acid. Polymers having ethylenically unsaturated bonds in their side chains are divalent carboxylic acids having unsaturated bonds in their side chains, such as itaconic acid, α-methylitaconic acid,
γ-methylitaconic acid, propylidene succinic acid,
Polyester obtained by polycondensation reaction with dihydroxy compounds such as α-ethylidene glutaric acid, ethylidene malonic acid, propylidene malonic acid, etc.
Examples include polyamides obtained by polycondensation reactions with diamines. Also suitable are polymers obtained by a polymer reaction between a polymer having a reactive functional group such as a hydroxyl group or a halogenated methyl group in its side chain and an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, or crotonic acid. It can be used for Examples of the polymers having functional groups having reactive activity include polyvinyl alcohol, copolymers of vinyl alcohol and vinyl acetate, polyepichlorohydrin, copolymers of vinyl alcohol and acrylonitrile, styrene, vinyl chloride, vinylidene chloride, etc. - Copolymers of hydroxyethyl methacrylate and acrylonitrile, metal methacrylate, butyl methacrylate, styrene, vinylidene chloride, vinyl acetate, etc.; polys obtained by the reaction of epichlorohydrin and 2,2-bis(4-hydroxyphenyl)-propane; Examples include ether, poly(4-hydroxystyrene), poly(N-methylolacrylamide), and the like.

Among the double bond-containing compounds described above, monomers of acrylic esters or methacrylic esters can be particularly preferably used.

As the photopolymerization initiation system, xanthene or thioxanthene compounds () are used. In the above formula (), specific examples of the halogen atom represented by X include chlorine and bromine. Also, Z
The lower alkoxy group represented by is methoxy,
Examples of the lower alkanoyloxy group include ethoxy and propoxy, and examples of the lower alkanoyloxy group include acetyloxy, propionyloxy, and butyryloxy. Further, specific examples of the lower alkyl group represented by ^R1 include methyl, ethyl, propyl, butyl, pentyl, hesyl, heptyl, octyl, nonyl,
Examples of hydroxy lower alkyl groups include hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, etc. Specific examples of lower alkoxy lower alkyl groups include methoxymethyl, methoxyethyl, methoxypropyl, ethoxyethyl, Ethoxypropyl, ethoxybutyl, propoxyethyl, propoxypropyl, etc. are examples of di-lower alkylamino lower alkyl groups, such as dimethylaminomethyl, dimethylaminoethyl, dimethylaminopropyl, diethylaminoethyl, diethylaminopropyl, diethylaminobutyl, etc. Specific examples of the group include phenyl, xylyl, tolyl, naphthyl, etc. Specific examples of the lower alkoxy group represented by ^R2 include methoxy, ethoxy, propoxy, etc., and specific examples of the di-lower alkylamino group include dimethyl. Examples include amino and diethylamino. Note that xanthene or thioxanthene dyes () are substances generally known in the literature. Moreover, upon use, it may contain isomers.

In addition to the above xanthene or thioxanthene dyes (), it further improves the sensitivity to light,
In order to complete curing in a shorter time, an appropriate photosensitizer may be added as necessary.

As the peroxide, one selected from organic peroxides is preferably used, and specific examples thereof include methyl ethyl ketone peroxide, cyclohexanone peroxide, 3,3,5-trimethylhexanone peroxide, methylcyclohexanone peroxide, and acetylacetone peroxide. , 1,1-bis(t-butylperoxy)-3,
3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, n
-Butyl-4,4-bis(t-butylperoxy)valerate, 2,2-bis(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, para Menthane hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3,-tetramethylbutyl hydroperoxide, di-t-butyl peroxide, t-butyl cumyl peroxide oxide, dicumyl peroxide, α,α'-bis(t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2 , 5-di(t-butylperoxy)hexyne-3, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, Succinic peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-trioyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate carbonate, dimethoxyisopropyl peroxycarbonate, di(3-methyl-3-methoxybutyl) peroxydicarbonate, t-butyl peroxydipivalate, t-butyl peroxyneodecanoate, t-butyl peroxyoctanoate ate, t-butylperoxy-3,5,5-
Trimethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate, di-t-butyl peroxyisophthalate,
Examples include 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butyl peroxide maleic acid, t-butyl peroxyisopropyl carbonate.

The ratio of photopolymerization initiator system (total of photosensitizer when used with xanthene or thioxanthene dye) to the ethylenically unsaturated double bond-containing compound is 1 part by weight of the former to 0.001 to 0.5 part by weight of the latter, Preferably it is 0.005 to 0.15 parts by weight. The ratio of the xanthene or thioxanthene dye and the photosensitizer used may be 1 part by weight of the former to 10 parts by weight or less, preferably 0.2 to 2 parts by weight.
When the proportion of the photopolymerization initiation system used is small, sufficient sensitivity cannot be obtained or a sufficient increase in sensitivity cannot be expected. If the proportion used is too high, the cured film will have a low molecular weight, resulting in a decrease in film strength and printing durability. The peroxide is usually used in an amount of 10 parts by weight or less, preferably 0.5 to 2 parts by weight, per 1 part by weight of the xanthene or thioxanthene dye.
If the amount used is below the above lower limit, a sufficient effect of increasing printing durability will not be observed. If the amount used exceeds the above upper limit, not only will no further improvement in printing durability be observed, but it will also have an adverse effect on other physical properties.

Although this is not particularly necessary if the double bond-containing compound has a sufficient molecular weight or glass transition point to form a film, an organic polymeric substance is usually blended as a binder. Such binders have various purposes for improving compatibility, film-forming properties, developability, adhesion, etc., and an appropriate type may be selected depending on the purpose. Specific examples include acrylic acid copolymers, methacrylic acid copolymers, itaconic acid copolymers, partially esterified maleic acid copolymers, acidic cellulose modified substances having carboxyl groups in side chains, and the like for improving aqueous developability.
Polyethylene oxide, polyvinylpyrrolidone, etc. are used, and to improve film strength and adhesion, polyethers of epichlorohydrin and phenol A, soluble nylon, polyalkyl methacrylates and polyalkyl acrylates such as polythimel methacrylate, etc. Alkyl methacrylate and acrylonitrile,
Copolymers of acrylic acid, methacrylic acid, vinyl chloride, vinylidene chloride, styrene, etc., copolymers of acrylonitrile and vinyl chloride, vinylidene chloride, vinylidene chloride, chlorinated polyolefins, copolymers of vinyl chloride and vinyl acetate, etc. Polymer, polyvinyl acetate, copolymer of acrylonitrile and styrene, copolymer of acrylonitrile and butadiene, styrene, polyvinyl alkyl ether, polvinyl alkyl ketone, polystyrene, polyamide, polyurethane, polyethylene terephthalate isophthalate, acetyl cellulose polyvinyl Butyral etc. can be mentioned. These binders are generally blended in an amount of 10 parts by weight or less, preferably 0.5 to 3 parts by weight, per 1 part by weight of the double bond-containing compound.

In addition to the above-mentioned components, the photosensitive resin layer may further contain a thermal polymerization inhibitor, a colorant, a plasticizer, a surface protective agent, a lubricant, a coating aid, etc., if necessary.

Examples of thermal polymerization inhibitors include hydroquinone,
Examples include p-methoxyphenol, pyrogallol, catechol, 2,6-di-t-butyl-p-cresol, and β-naphthol. Examples of colorants include pigments such as phthalocyanine pigments, azo pigments, carbon black, and titanium oxide, triphenylmethane dyes, azo dyes, and anthraquinone dyes. The amount of these thermal polymerization inhibitors and colorants added is 0.01 to 3% by weight of thermal polymerization inhibitor and colorant based on the total weight of double bond-containing compound and binder.
0.001 to 10% by weight is preferred. Examples of plasticizers include dioctyl phthalate, didodecyl phthalate, dibutyl phthalate, butylbenzyl phthalate, triethylene glycol dicaprylate,
Dimethyl glycol phthalate, tricresyl phosphate, dioctyl adipate, dibutyl adipate, dibutyl sebacate, dibutyl maleate, triacetyl glycerin, etc.
It can be blended in an amount of % by weight or less.

In order to form the photosensitive resin layer, the composition containing the above-mentioned essential components and optional components may be coated on the support as it is or dissolved in a suitable solvent, and then dried. Examples of solvents include methyl ethyl ketone, acetone, cyclohexanone, ethyl acetate,
Butyl acetate, amyl acetate, ethyl propionate,
Examples include toluene, xylene, benzene, monochlorobenzene, chloroform, carbon tetrachloride, trichloroethylene, trichloroethane, dithymelformamide, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, pentoxone, methanol, ethanol, and propanol.

There are no particular restrictions on the thickness of the photosensitive resin layer, but
In view of the use as a lithographic printing plate, it is desirable to make the film as thin as possible within the limits of image formation, and the film thickness is usually about 0.5 to 7 μm, preferably about 1 to 3 μm.

Note that the photosensitive resin layer may further be subjected to known techniques for preventing adverse effects such as a decrease in sensitivity and deterioration of storage stability due to oxygen. For example, a removable transparent cover sheet may be provided on the photosensitive layer, or a coating layer may be provided using a waxy substance having low oxygen permeability, a water-soluble or alkali water-soluble polymer, or the like.

The photosensitive resin layer of the lithographic plate material of the present invention obtained in this manner can be prepared by carbon arc, high pressure mercury lamp,
This can be cured using general-purpose light sources including ultraviolet and visible light of 180 nm or higher, such as xenon lamps, metal halide lamps, fluorescent lamps, tungsten lamps, argon ion lasers, helium cadmium lasers, krypton lasers, but especially laser light. By simultaneously performing image formation and curing by irradiation with , it is possible to efficiently produce a lithographic printing plate that is oleophilic and has excellent printing durability. Note that development after irradiation may be carried out using an appropriate developer capable of dissolving the photosensitive resin, depending on the composition of the photosensitive resin layer.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Preparation of lithographic printing plate After dissolving 1.0 g of methymethacrylate/methacrylic acid copolymer (BR-77 manufactured by Mitsubishi Rayon) in 10 g of methyl ethyl ketone, 1.0 g of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry) was dissolved in this. is dissolved to obtain the first liquid. Thioxanthene dye (I: A=S; X=H; Y=C; Z
= _OC2H5 ; ^R1 = _C6H5 ; _R2 = ^H ) 60mg, _di -t-
A second solution is obtained by dissolving 60 mg of butyl perisophthalate and 10 mg of methquinone (p-methoxyphenol) in 3 g of methyl cellosolve. The second liquid was added to the first liquid and stirred well to obtain a photosensitive liquid.

The above photosensitive solution was applied to a grained and anodized aluminum support using a bar coater at a coating weight of 2 g/m ² and then heated at 60°C for 30 minutes.
Dry for a minute. Next, use a bar coater to coat 2g/
An overcoat layer was provided by applying a 5% aqueous solution of polyvinyl alur (saponification degree 88%, polymerization degree 500) to a coating amount of m ² to obtain a lithographic plate material.

Sensitivity measurement Kodak step tablet No. 2 (21step) and
The above lithographic plates were stacked together, and light with a wavelength of around 490 nm (light intensity) was extracted from a xenon lamp (Ushio, 150W) through a filter.
4.0 mW/cm ² ) was irradiated from above for 10 seconds. When developed with a developer (10 parts by weight of anhydrous sodium carbonate, 50 parts by weight of butyl cellosolve and 3 parts by weight of an activator dissolved in 1000 parts by weight of water), the number of photocured stages was 13. From this, it has become clear that this lithographic plate material can form images with an exposure dose of around 0.5 mJ/cm ² .

Laser platemaking and printing Laser light (488nm) is focused from an argon ion laser light source with an output of 0.5W through an optical system to a beam diameter of 20μ, and is cylindrical scanned (1000rpm, 600 lines/inch) on the planographic plate material while being modulated by a modulator. )did.
Next, this was developed with the developer described above and desensitized with gum arabic. When offset printing was performed using this printing plate, it was possible to obtain up to 700,000 prints without any problems.

Comparative Example 1 A lithographic plate material was obtained in the same manner as in Example 1, except that 60 mg of N-phenylglycine was used instead of 60 mg of di-t-butyl perisophthalate. Example 1
When sensitivity was measured under the same conditions as above, the number of photocured stages was 11. This revealed that this lithographic plate material can form images with an exposure dose of around 1 mJ/cm ² .

Next, laser platemaking was performed using the above planographic plate material under the same conditions as in Example 1, and offset printing was performed using the obtained printing plate, and it was possible to obtain printed matter without any problems. The total number of copies sold was up to 450,000. Furthermore, when the laser output was changed to 0.8W, the number of sheets could be up to 500,000 sheets.

Example 2 As a xanthene dye (:A=O;X=
Cl; Y=N; Z=O; R ¹ = C ₂ H ₅ O(CH ₂ ) ₃ ; R ² =
A lithographic plate material was obtained in the same manner as in Example 1 except that 60 mg of N(C ₂ H ₅ ) ₂ ) was used. When sensitivity was measured under the same conditions as in Example 1, the number of photocured stages was 12.
It was hot on the steps. From this, this lithographic plate material is 0.5~
It has become clear that image formation is possible with an exposure amount of around 1.0 mJ/cm ² .

Next, laser platemaking was performed using the above planographic plate material under the same conditions as in Example 1, and offset printing was performed using the obtained printing plate, and there was no problem at least up to 700,000 sheets. I was able to obtain a printed copy.

Comparative Example 2 2,4,6-tris(trichloromethyl)- instead of 60 mg of di-t-butylperisophthalate
A lithographic plate material was obtained in the same manner as in Example 2 except that 60 mg of 1,2,5 triazine was used. When sensitivity was measured under the same conditions as in Example 1, the number of photocured stages was 10. From this point on, this lithographic plate material is
It has become clear that image formation is possible with an exposure amount of around 1.0 to 1.5 mJ/cm ² .

Next, laser platemaking was performed using the above planographic plate material under the same conditions as in Example 1, and offset printing was performed using the obtained printing plate, and it was possible to obtain printed matter without any problems. The number of copies sold was up to 500,000.

Example 3 1,1,4,4-tetramethylbutane-1, instead of 60 mg of di-t-butylperisophthalate
A lithographic plate material was obtained in the same manner as in Example 1 except that 60 mg of 4-diol diperbenzoate was used. When sensitivity was measured under the same conditions as in Example 1,
The number of stages photocured was 13. From this, it has become clear that this lithographic plate material can form images with an exposure dose of around 0.5 mJ/cm ² .

Next, laser platemaking was performed using the above planographic plate material under the same conditions as in Example 1, and offset printing was performed using the obtained printing plate, and there was no problem at least up to 700,000 sheets. I was able to obtain a printed copy.

Example 4 Instead of 1.0 g of methyl methacrylate/methacrylic acid copolymer (BR-77), 1.0 g of a partial methyl cell half ester of styrene/maleic acid copolymer (molecular weight approximately 70,000, acid value 80) was used. A lithographic plate material was obtained in the same manner as in Example 1 except for this. When sensitivity was measured under the same conditions as in Example 1,
The number of stages photocured was 12. From this, it has become clear that this lithographic plate material can form an image with an exposure amount of approximately 0.5 to 1.0 mJ/cm ² .

Next, laser platemaking was performed using the above planographic plate material under the same conditions as in Example 1, and offret printing was performed using the obtained printing plate, and there was no problem at least up to 500,000 sheets. I was able to obtain a printed copy.

[Effects of the Invention] The lithographic plate material of the present invention is characterized in that its photosensitive resin layer contains a xanthene or thioxanthene dye () and a peroxide that are sensitive to laser beams, and as a result, it has a negative Image formation and curing can be achieved at the same time without the use of lithographic plates, and lithographic plates can be manufactured efficiently. Furthermore, the cured resin layer of the obtained lithographic printing plate generally exhibits good lipophilicity and printing durability.

Claims (1)

[Claims] 1. A support having a hydrophilic surface, an addition-polymerizable compound having an ethylenically unsaturated double bond provided on the surface, and the formula [In the formula, A is an oxygen atom or a sulfur atom, ) is a double bond, and if Y is a nitrogen atom, the bond with the adjacent carbon atom is a single bond.), Z is the oxygen atom (in this case, the bond with the adjacent carbon atom is a double bond). ), lower alkoxy group or lower alkanoyloxy group, R ¹ is lower alkyl group, hydroxy lower alkyl group, lower alkoxy lower alkyl group, di-lower alkylamino lower alkyl group or aryl group, R ² is lower alkoxy or di-lower alkylamino group. In addition, Z and
R ¹ is both −Z−R ¹ −, It may also represent ] Characterized by consisting of a photopolymerization initiation system containing a xanthene or thioxanthene dye shown as an essential component and a photosensitive resin layer containing a peroxide,
A lithographic plate material that is sensitive to visible light and provides a lithographic printing plate with good printing durability. 2. The lithographic plate material according to claim 1, wherein the ratio of the xanthene or thioxanthene dye and peroxide is 1 part by weight of the former to 10 parts by weight or less of the latter. 3. The lithographic plate material according to claim 1, wherein the addition-polymerizable compound having ethylenically unsaturated double bonds has at least two ethylenically unsaturated double bonds in one molecule. 4. The lithographic plate material according to claim 3, wherein the addition-polymerizable compound having an ethylenically unsaturated double bond is a substance having a boiling point of 100°C or higher. 5. The lithographic plate material according to claim 1, wherein the ratio of the addition-polymerizable compound having an ethylenically unsaturated double bond and the photopolymerization initiation system is 1 part by weight of the former to 0.001 to 0.5 part by weight of the latter. . 6. The lithographic plate material according to claim 1, wherein the photosensitive resin layer has a thickness of 0.5 to 7 μm. 7. The lithographic plate material according to any one of claims 1 to 6, wherein the photosensitive resin layer further contains a binder. 8 The amount of binder is 10 parts by weight of the addition polymerizable compound having an ethylenically unsaturated double bond.
The lithographic plate material according to claim 7, which does not exceed parts by weight.