JP2956102B2 - Photosensitive composition for lithographic printing plate - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a positive photosensitive composition having a novel o-quinonediazide compound and an alkali-soluble resin, and more particularly, to lithographic printing. The present invention relates to a photosensitive composition suitable for producing a plate and a photosensitive film material.

[Conventional technology]

o-naphthoquinonediazidosulfonic acid ester, o-
A photosensitive composition comprising an o-quinonediazide compound such as naphthoquinonediazidosulfonamide and an alkali-soluble resin such as a novolak-type phenol resin and a novolak-type cresol resin is a photosensitive layer of a photosensitive lithographic printing plate, or a photolithographic printing plate. It is used industrially as a resist and the like.

The o-quinonediazide compound is decomposed by the action of actinic rays to produce a compound having a carboxylic acid group, and becomes alkali-soluble. Utilizing this property, a photosensitive composition containing an o-quinonediazide compound is image-exposed to a photosensitive material provided on a suitable support, and developed with an aqueous alkaline solution to form an original image in which the image portion is dissolved and removed. On the other hand, a positive relief image can be obtained.

The o-quinonediazide compound itself has poor film-forming properties, has crystal-precipitating properties, and has low wear resistance required as printing durability when used as a lithographic printing plate, and is therefore practical. It does not become a photosensitive composition. For this reason, alkali-soluble resins such as novolak-type phenol resins and novolak-type cresol resins have been generally used together with the o-quinonediazide compound.

However, due to the properties of the novolak resin, the adhesion to the support is poor, the film is brittle, the chemical resistance is low, the coating properties are poor, the abrasion resistance is insufficient, and when used as a lithographic printing plate And it is difficult to obtain sufficient printing durability.

In order to solve such a problem, various o-quinonediazide compounds have been proposed. For example,
No. 45127, which is obtained by esterifying o-quinonediazidosulfonyl chloride to a polyester having a hydroxyl group at a terminal; N- (4-hydroxyphenyl) described in JP-B-50-24641
Examples thereof include those obtained by esterifying o-quinonediazidosulfonyl chloride with a homopolymer of methacrylamide or a copolymer with another copolymerizable monomer.

However, although the adhesion to the support, the fragility of the coating, and the coating properties have been improved to some extent, there is still a problem that the abrasion resistance is insufficient and the range of appropriate development conditions is narrow. It is rare.

[Problems to be solved by the invention]

Accordingly, an object of the present invention is to provide a novel photosensitive composition for a lithographic printing plate, which has good adhesion to a support, provides a flexible film having good abrasion resistance, and has a wide range of appropriate developing conditions. It is to provide.

[Means for solving the problem]

The present inventors have solved the above-mentioned problem by providing a photosensitive composition containing a photosensitive polyester resin having an o-quinonediazide group in a side chain and an alkali-soluble resin.

The photosensitive polyester resin having an o-quinonediazide group in the side chain used in the present invention is, for example, (i) a polycarboxylic acid component containing a dicarboxylic acid having a phenolic hydroxyl group or a derivative thereof and a polyhydric alcohol component. (B) a polyester having an alcoholic hydroxyl group obtained by reacting a polycarboxylic acid component containing a dicarboxylic acid having a phenolic hydroxyl group or a derivative thereof with a polyhydric alcohol component; Compounds having two or more functional groups in the molecule having higher reactivity to alcoholic hydroxyl groups than phenolic hydroxyl groups in the polyester [hereinafter referred to as chain extenders. To obtain a modified polyester having a phenolic hydroxyl group, and a polyester or modified polyester having a phenolic hydroxyl group in the side chain synthesized in the above (a) or (b) and o having a halogenosulfonyl group. -It is obtained by reacting a quinonediazide compound.

Polyester or modified polyester having a phenolic hydroxyl group in the side chain [hereinafter, polyester or modified polyester is generically referred to as (modified) polyester]
May have another bond which does not react with the phenolic hydroxyl group, such as urethane, amide, ureide, ether bond, etc., in the polyester chain, if necessary.

As a dicarboxylic acid having a phenolic hydroxyl group,
For example, dicarboxylic acids represented by the following general formulas (1) to (5) can be exemplified.

(In the general formula (1) ~ (5), R 1 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a halogen atom or a nitro group, R ₂ and R ₃
Independently represents a hydrogen atom, a halogen atom, a nitro group or a cyano group; X represents an alkylene group having 1 to 6 carbon atoms;
Oxygen atom, sulfur atom, And i represents an integer of 1 to 5, and j is (5-j)
H and h 'independently represent an integer of 1 to 4, f represents 0 or 1, g represents an integer of (4-h), and g' represents (4-h ') Represents an integer. Examples of the above-mentioned dicarboxylic acid having a phenolic hydroxyl group and derivatives thereof include 4-hydroxybenzylidenemalonic acid, 3-hydroxybenzylidenemalonic acid, 3,4-dihydroxybenzylidenemalonic acid, and 4-hydroxybenzylidenemalonic acid.
Hydroxy-3-methoxybenzylidenemalonic acid, 3-
Hydroxy-4-methoxybenzylidenemalonic acid, 4-
Hydroxy-3-nitrobenzylidenemalonic acid, 4-hydroxycinnamylidenemalonic acid, 3-hydroxyzinnamylidenemalonic acid, 4-hydroxy-3-methoxycinnamylidenemalonic acid, 4-hydroxy-3-nitrocinnamylidene Hydroxymalonic acids such as malonic acid; 3-hydroxyphthalic acid, 4-hydroxyphthalic acid, 4-hydroxyisophthalic acid, 5-hydroxyisophthalic acid, hydroxyterephthalic acid, 3,6-dihydroxyphthalic acid,
2,5-dihydroxyisophthalic acid, 4,5-dihydroxyisophthalic acid, 2,3-dihydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, 2,4,6-trihydroxyisophthalic acid, 4,5,6-tricarboxylic acid Hydroxyisophthalic acid, 4-
Hydroxyphthalic acids such as hydroxy-5-nitroisophthalic acid, 4-hydroxy-5-chloroisophthalic acid, 3-hydroxy-6-methoxyphthalic acid, and 2,4-dihydroxy-6-methylisophthalic acid; 3,3′- Methylenebis (4-hydroxybenzoic acid), 4,6'-dihydroxy-
Hydroxybiphenyl such as 3,3'-biphenyldicarboxylic acid, 6,6'-dihydroxy-5,5'-dimethoxy-3,3'-biphenyldicarboxylic acid, and 4,5-dihydroxy-2,4'-oxydibenzoic acid Dicarboxylic acids; 2-hydroxy-
p-benzenediacetate, 2,5-dihydroxy-p-benzenediacetate, α, α'-dicyano-2,5-dihydroxy-
p-benzenediacetate, α, α'-dinitro-2,5-dihydroxy-p-benzenediacetate, α, α'-dichloro-
Hydroxybenzene diacetates such as 2,5-dihydroxy-p-benzenediacetic acid and 5-hydroxy-m-phenylenedioxy (oxyacetic acid); dialkyl esters such as dimer esters and diethyl esters of the above dicarboxylic acids; Examples thereof include di (alkylene glycol) esters such as (ethylene glycol) ester and di (propylene glycol) ester.

In the production of polyester, other polycarboxylic acids or derivatives thereof can be used in combination with the above-mentioned dicarboxylic acids having a phenolic hydroxyl group or derivatives thereof, and such compounds include succinic acid, adipic acid, azelaic acid, and sebacic acid. , Phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid,
Tetrabromophthalic acid, tetrachlorophthalic acid, 1,4-
Cyclohexanedicarboxylic acid, maleic acid, fumaric acid,
Polycarboxylic acids such as itaconic acid, carboxynorbornaneacetic acid, 5-sodium sulfoisophthalic acid, trimellitic acid and hymic acid, or anhydrides or ester derivatives thereof can be used.

On the other hand, as the polyhydric alcohol component, various types can be used without particular limitation, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, neopentyl glycol, 1,3- Aliphatic chain diols such as butylene glycol, 1,6-hexanediol, 2-butene-1,4-diol, 2,2,4-trimethyl-1,3-pentanediol;
1,4-bis-β-hydroxyethoxycyclohexane,
Cyclohexanedimethanol, tricyclodecanedimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, ethylene oxide adduct of bisphenol F, propylene oxide addition of bisphenol F Isomer, hydrogenated bisphenol A ethylene oxide adduct, hydrogenated bisphenol A propylene oxide adduct, tricyclodecane dimethanol ethylene oxide adduct, tricyclodecane dimethanol propylene oxide adduct, 5-
Aliphatic and aromatic cyclic diols such as norbornene-2,3-dimethanol and 5-norbornene-2,2-dimethanol; triols such as trimethylolpropane; and tetraols such as pentaerythritol.

Polyester having a phenolic hydroxyl group in the side chain,
Means usually known in the art, for example,
Polymerization reaction 9, polycondensation ", can be easily produced by the method described in Ogata, published by Kagaku Dojinsha, or described in U.S. Pat. No. 3,622,320, JP-A-60-165646.

Examples of the chain extender that can be used in the method (b) include a diaryl oxalate compound, a diaryl phthalate compound, and a diaryl carbonate compound.

The diaryl oxalate compound is represented by the following general formula (6), the diaryl phthalate compound is represented by the following general formula (7), and the diaryl carbonate compound is represented by the following general formula (8). Can be listed.

(In the above general formulas (6) to (8), R ₁ and R ₂ each independently represent an aromatic hydrocarbon group which may have a substituent.) R ₁ and R in the above general formulas _As a specific example of ₂ , (N is an integer of 1 to 10), (X is a halogen atom), And the like.

The modified polyester having a phenolic hydroxyl group in the side chain by the reaction between the polyester and the chain extender can be easily produced, for example, by the method described in JP-A-60-221748.

The structure and molecular weight of the (modified) polyester can be set to arbitrary values over a wide range by changing the selection of the polyhydric carboxylic acid component, the polyhydric alcohol component, the chain extender, and the synthesis conditions in various ways. In order to provide the intended use, those having a weight average molecular weight of 1,000 to 100,000 are preferable, and further, a polyester or a modified polyester.
It is preferable that 1000 g or more of the structural units represented by the general formulas (1) to (5) be contained in an amount of 1.0 mol or more.

The (modified) polyester having a phenolic hydroxyl group in the side chain thus obtained and the o-quinonediazide compound having a halogenosulfonyl group are subjected to a condensation reaction.
For example, the (modified) polyester is dissolved in a suitable organic solvent (for example, dioxane, tetrahydrofuran), and an o-quinonediazide compound having a halogenosulfonyl group in an amount corresponding to a desired degree of esterification is added, followed by stirring at room temperature to 50 ° C. The esterification can be easily performed by adding an alkali agent such as sodium carbonate and triethylamine to the equivalent point, and thereafter, the reaction solution is poured into a large amount of water, the reaction product is precipitated, filtered, and further filtered. By washing and drying the precipitate, a photosensitive polyester resin having an o-quinonediazide group in the side chain of the present invention can be obtained.

An o-quinonediazide compound having a halogenosulfonyl group has at least one halogenosulfonyl group (-SO
₂ X group: wherein X represents a halogen atom) and at least one o-quinonediazide group, for example, 1,2-naphthoquinone-2-diazide-
5-sulfonyl chloride, 1,2-naphthoquinone-2-
Examples thereof include diazido-4-sulfonyl chloride and 1,2-benzoquinone-2-diazide-4-sulfonyl chloride.

Not all of the phenolic hydroxyl groups of the (modified) polyester having a phenolic hydroxyl group in the side chain need be subjected to condensation with the o-quinonediazide compound, and some of the phenolic hydroxyl groups have condensed with the o-quinonediazide compound. By itself, it becomes alkali-soluble by irradiation with actinic rays, but it is particularly preferable that 20% or more of the phenolic hydroxyl groups are condensed with the o-quinonediazide compound.

A known o-quinonediazide compound can be used in combination with the photosensitive polyester resin having an o-quinonediazide group in the side chain of the present invention. Known o-quinonediazide compounds are compounds having at least one o-quinonediazide group, which increase the solubility in an aqueous alkali solution by actinic rays, and have various structures, for example, J. KOSAR By Light-Sensitive System
s "(John Wiley & Sons, Inc., published in 1965) P. 336-P352
In more detail. In particular, various hydroxyl compounds and sulfonic acid esters of o-benzo or o-naphthoquinonediazide are preferred.

As a typical specific example, 1,2-naphthoquinone-2-
Ester of diazido-5-sulfonyl chloride with phenol-formaldehyde resin or cresol-formaldehyde resin; 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride and pyrogallol acetone described in U.S. Pat. No. 3,635,709. Esters with resins; 1,2 described in JP-B-63-13528
Esters of naphthoquinone-2-diazide-5-sulfonyl chloride and resorcinol-benzaldehyde resin; 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride and resorcinol-pyrogallol described in JP-B-62-44257. An ester with an acetone co-condensation resin; a polyester obtained by esterifying 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride to a polyester having a hydroxyl group at a terminal described in JP-B-56-45127; The homopolymer of N- (4-hydroxyphenyl) methacrylamide or a copolymer with another copolymerizable monomer described in Japanese Patent Publication No. 50-24641 may be modified with 1,2-naphthoquinone-2-diazide-5. -Esterified sulfonyl chloride; JP-B-54
1,2-Naphthoquinone-2 described in -29922
Esters of diazide-5-sulfonyl chloride with bisphenol-formaldehyde resin;
No. 043, a p-hydroxystyrene homopolymer or a copolymer with another copolymerizable monomer obtained by esterifying 1,2-naphthoquinone-2-diazido-5-sulfonyl chloride; There are esters of 1,2-naphthoquinone-2-diazide-5-sulfonyl chloride with polyhydroxybenzophenone. Other known o-quinonediazide compounds that can be used in the present invention include JP-A-63-80254, JP-A-58-5737, and JP-A-58-5737.
7-111530, JP-A-57-111531, JP-A-57-114138
No., JP-A-57-142635, JP-A-51-36129, Japanese Patent Publication No. 6
Examples thereof include those described in each gazette such as JP-A-2-3411, JP-B-62-51459, and JP-B-51-483.

The total content of the photosensitive polyester resin having an o-quinonediazide group in the side chain of the present invention and a known o-quinonediazide compound is 5 to 5% based on the total solid content of the photosensitive composition.
It is 60% by weight, more preferably 10 to 40% by weight.

As the alkali-soluble resin used in the present invention, for example, phenol-formaldehyde resin, cresol-formaldehyde resin, phenol-cresol-formaldehyde co-condensation resin, phenol-modified xylene resin, polyhydroxystyrene, polyhalogenated hydroxystyrene, N- Copolymers of (4-hydroxyphenyl) methacrylamide, copolymers of hydroquinone monomethacrylate, and resins having a carboxyl group such as styrene / maleic anhydride copolymer, methyl methacrylate / methacrylic acid copolymer, etc. No. Further, a (modified) polyester having a phenolic hydroxyl group on a side chain, which is a precursor of a photosensitive polyester resin having an o-quinonediazide group on a side chain of the present invention, may also be used. Such an alkali-soluble resin is used in an amount of 70% by weight or less of the total composition.

In the composition of the present invention, if necessary, a cyclic acid anhydride for enhancing sensitivity, a printing-out agent for obtaining a visible image immediately after exposure, a dye as an image coloring agent, other fillers, and the like. Can be added.

Examples of the cyclic acid anhydride include succinic anhydride, glutaric anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, chloromaleic anhydride, and pyromellitic anhydride. These cyclic anhydrides can be contained in an amount of 1 to 15% by weight of the whole composition.

Examples of the printing-out agent for obtaining a visible image immediately after exposure include a combination of a photosensitive compound that releases an acid upon exposure and an organic dye that forms a salt with the acid and changes color.

Examples of the photosensitive compound that releases an acid upon exposure include o-naphthoquinonediazide-4-sulfonic acid halogenide described in JP-A-50-36209;
Trihalomethyl-2 described in JP-A-53-36223
-Pyrone and trihalomethyl-S-triazine;
Various o-naphthoquinonediazide compounds described in JP-A-62444; 2-trihalomethyl-5-aryl-1,3,4-oxadiazole compounds described in JP-A-55-77742; And diazonium salts. These compounds can be used alone or as a mixture, and the amount of addition is preferably 0.3 to 15% by weight.

Examples of the organic dye capable of forming a salt include triphenylmethane dyes, cyanine dyes, diazo dyes, styryl dyes, and the like.Specific examples include crystal violet, ethyl violet, methyl violet, methylene blue, and Victoria Blue BH. , Victoria Pure Blue BOH, Oil Blue # 603, Malachite Green, Oil Green BG, Brilliant Green, Fuchsin, Eosin, Rhodamine B, Oil Pink # 312,
Oil Red 5B, Oil Black BS, Oil Yellow #
101, phenolphthalein, cresol red, auramine, leuco crystal violet, leucomalachite green, and the like.
It is preferable to add 0.3 to 15% by weight.

Others, in the composition of the present invention, various resins having a hydrophobic group for improving ink inking property of an image, for example, octylphenol / formaldehyde resin, t-butylphenol / formaldehyde resin, t-butylphenol / benzaldehyde resin, rosin-modified Novolak resins and o-naphthoquinonediazidesulfonic acid esters of these modified novolak resins; additives for improving coating properties, such as cellulose alkyl ethers, ethylene oxide surfactants, fluorine surfactants (for example, Megafac F manufactured by Nippon Ink Chemical Industry Co., Ltd.
-177); plasticizers for improving the flexibility of the coating film, such as dibutyl phthalate, dioctyl phthalate, butyl glycolate, tricresyl phosphate, dioctyl adipate, and various additives for various purposes. Can be added. The addition amount of these is preferably 0.01 to 30% by weight.

Further, a known resin for further improving the abrasion resistance of the film can be added to these compositions. These resins include polyvinyl acetal resin, polyurethane resin, epoxy resin, vinyl chloride resin, nylon, polyester resin, acrylic resin and the like, and can be used alone or in combination. The addition amount is preferably 2 to 40% by weight.

The composition of the present invention is dissolved in a solvent that dissolves the above-mentioned components, and applied on a support. As the solvent used here, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methanol, ethanol, propanol, butanol, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, There are butyl acetate, acetone, dioxane, tetrahydrofuran, cyclohexanone, γ-butyrolactone, toluene, ethylene dichloride, tetrachloroethane, dimethylformamide and the like, and these solvents can be used alone or as a mixture. The solid content concentration in the above components is 2 to 50% by weight.

The photosensitive composition of the present invention dissolved in a solvent as described above is coated with a whitener, a dip, a curtain,
The support is applied to the support by a known application method such as roll application, spray application, wheeler application, spinner application, air knife application, doctor knife application, and the like. As a support,
For example, a metal plate of aluminum, zinc, copper, stainless steel, iron, etc .; a plastic film of polyethylene terephthalate, polycarbonate, polyvinyl acetal, polyethylene, etc .; a paper coated with a synthetic resin melt-coated or a synthetic resin solution, or a metal layer formed on a plastic film. Composite materials provided by techniques such as vacuum deposition and lamination; and other various materials used as a support for a printing plate. In the case of a support having a metal surface, particularly an aluminum surface, it is preferable that a surface treatment such as a graining treatment, an anodic oxidation treatment, and a hydrophilic treatment is performed. The amount of coating is usually about 0.5 to about 5 g / m ² on a dry weight basis.

After coating, the coating is dried by a known method to obtain a photosensitive lithographic printing plate provided with a photosensitive layer on a support.

After performing image exposure with a positive image on the photosensitive layer of the photosensitive lithographic printing plate, developing with an alkali developer and dissolving and removing the exposed portion yields a lithographic printing plate having a corresponding image formed on a support. can get.

Suitable light sources used for exposure include, for example, carbon arc lamps, mercury lamps, metal halide lamps, xenon lamps, chemical lamps, lasers, and the like.

As the alkaline developer, water is a main component, sodium silicate, potassium silicate, sodium metasilicate, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, sodium tertiary phosphate,
It is appropriate to add an alkali agent such as dibasic sodium phosphate, tribasic ammonium phosphate, dibasic ammonium phosphate, monoethanolamine, diethanolamine, and triethanolamine, and the concentration thereof is 0.1 to 10% by weight. Preferably it is 0.5 to 5% by weight.

In addition, an alkaline buffer, a surfactant, an alcohol, and the like can be added to the alkali developer as needed.

The photosensitive composition of the present invention is extremely useful as a photosensitive composition for a lithographic printing plate, but is not necessarily limited to this use, and may be used for an image forming material such as a photosensitive film. It is a good thing.

Hereinafter, the present invention will be described specifically with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

〔Example〕

Examples 1 to 6 and Comparative Example 1 [1-1] Synthesis of (Modified) Polyester One-Step Method: Each mixture having the composition shown in Table 1 was mixed with a catalyst (3.0 g of dibutyltin oxide) with a stirrer and nitrogen. The reactor was equipped with a gas inlet tube, a thermometer, and a distilling tube, and heated to 190 ° C. while stirring under a nitrogen gas atmosphere to start a reaction.

Thereafter, the heating and stirring were continued for 3 hours, and the distillation of the alcohol generated by the reaction was stopped. After that, the pressure in the reactor was gradually reduced to 1 mmHg at the same temperature. Thereafter, the mixture was further heated and stirred under the same reduced pressure for about 3 hours, and after distilling off the distillate, the pressure in the reactor was returned to normal pressure with nitrogen gas to obtain a polyester having a phenolic hydroxyl group in a side chain. Was.

Two-stage method: Following the one-stage method, the temperature in the reactor is set to 180 ° C
The chain extender described in Table 1 was charged with stirring, the pressure in the reactor was again adjusted to 1 mmHg, and stirring was continued for 2 hours at the same temperature to distill off by-produced phenol.
After returning to normal pressure, a modified polyester having a phenolic hydroxyl group in the side chain was obtained.

[1-2] Synthesis of a photosensitive polyester resin having an o-quinonediazide group in the side chain 100 g of the (modified) polyester synthesized in [1-1] and 1,2-naphthoquinone-2-ene in the amount shown in Table 1 Dissolve diazide-5-sulfonyl chloride in dioxane and add 25
% By weight. Then, a 50% by weight aqueous solution of triethylamine was added dropwise while stirring at 40-50 ° C until the reaction system was completely neutralized. After the completion of the dropwise addition, the mixture was stirred for 1 hour, and then the reaction solution was poured into 10 times the volume of cold water. The precipitated yellow precipitate was washed with water and dried, and dried to obtain a photosensitive polyester resin having an o-quinonediazide group in the side chain. I got

[2] Creating a photosensitive lithographic printing plate A 0.30 mm thick aluminum plate was
A 0-mesh aqueous suspension of pamistone is used to grain the surface, and then the current density is 2 A / dm ^{2 in a} 20% sulfuric acid electrolyte.
To form an oxide film of 2.7 g / m ² , washed with water and dried to obtain a support.

The following photosensitive solution is applied to this support with a roll coater,
The photosensitive lithographic printing plate was dried at 100 ° C. for 3 minutes. At this time, the weight of the dried coating film was 2.0 g / m ² .

[3] Preparation of a lithographic printing plate A halftone dot positive image film and a step 0.15 step wedge are brought into close contact with the photosensitive lithographic printing plate obtained in [2],
A metal halide lamp with an output of 1 kW (1 m from Iwasaki Electric Co., Ltd.)
0 ").

Thereafter, development was performed with an 8-fold diluted aqueous solution of a commercially available developer “DP-4” (manufactured by Fuji Photo Film Co., Ltd.) at 25 ° C. for 1 minute to obtain a lithographic printing plate.

[4] Evaluation of development tolerance and printing durability (wear resistance) Development tolerance: The photosensitive lithographic printing plate prepared in [2] was exposed under the same exposure conditions as [3], and subsequently in the same manner as described above. And the number of clear steps of the step wedge was measured and compared with the number of clear steps at the time of development for 1 minute. The smaller the difference in the number of clear stages, the better the development tolerance.

Printing durability: The lithographic printing plate prepared in [3] was mounted on a Roland Fabolit printing press, and printing was performed using a commercially available lithographic printing ink. The presence or absence was evaluated.

 Table 1 shows the results.

[Effect of the Invention] When the photosensitive composition of the present invention is used for a photosensitive lithographic printing plate, it has good abrasion resistance and good development tolerance.

Claims (1)

(57) [Claims] 1. A photosensitive composition for a lithographic printing plate comprising a photosensitive polyester resin having an o-quinonediazide group in a side chain and an alkali-soluble resin.