JPH06317897A - Photosensitive planographic printing plate - Google Patents

Abstract

PURPOSE:To obtain a photosensitive planographic printing plate showing good initial ink build-up property, causing no defects by gum so that build-up failure of printing inks is not caused even lots of sheets are printed, by incorporating a specified amt. of t-butyl substd. polyvinylphenol resin as a sensitizer. CONSTITUTION:This photosensitive planographic printing plate has a photosensitive layer containing a diazo resin, polymer compd., and sensitizer and contains 0.05-20wt.% t-buthyl substd. polyvinylphenol resin as the sensitizer. The amt. of t-butyl substd. polyvinyl phenol resin is preferably 0.1-15wt.%, more preferably 0.1-10wt.%. If the amt. is less than 0.05wt.%, the ink build-up property is deteriorated. If the amt. exceeds 20wt.%, the developing property degrades. Further if necessary, a coloring agent, storage stabilizer, plasticizer, surfactant, etc., may be added to the photosensitive layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive lithographic printing plate, more specifically, a negative type photosensitive lithographic printing plate excellent in ink receptivity (oil sensitivity), development stability and printing durability. Regarding the edition.

[0002]

2. Description of the Related Art Generally, a negative type photosensitive lithographic printing plate is prepared by coating a photosensitive composition on a support plate such as an aluminum plate,
By irradiating it with actinic rays such as ultraviolet rays through a negative image, the light-irradiated parts are polymerized or cross-linked to be insolubilized in the developing solution, and the non-irradiated parts are eluted in the developing solution, and each part is converted into water. It can be obtained by forming an image area that repels and receives the oil-based ink and a non-image area that receives water and repels the oil-based ink.

As the above-mentioned photosensitive composition (photosensitive layer),
A combination of a high molecular compound with a diazo resin such as a condensate of p-diazodiphenylamine and formaldehyde is widely used, and a high molecular compound having a hydroxyl group in its molecule is used. Examples of such a photosensitive composition are those composed of a polymer of a diazo resin and a hydroxyalkyl (meth) acrylate described in JP-B-52-7364, JP-B-57-
Japanese Patent Publication No. 57-5165, which is composed of a diazo resin and a polymer having an aromatic hydroxyl group described in Japanese Patent No. 43890.
Examples thereof include those composed of a polymer containing a diazo resin and a hydroxy-phenoxypropyl (meth) acrylate monomer unit described in JP-A-6.

However, when a photosensitive composition containing a polymer compound as described above is used as a lithographic printing plate, the initial ink receptivity is poor, and the "gum loss phenomenon" is caused even by the gum solution used in the finishing step. There is a problem of causing. The "gum loss phenomenon" refers to a hydrophilic film (generally gum arabic or an aqueous solution of a water-soluble resin is widely used) applied to the plate surface after development in order to protect the hydrophilicity of the non-image area. , A phenomenon in which the ink acceptability of an image decreases. In order to improve ink receptivity (that is, ink receptivity and oil sensitivity), a technique is known in which various compounds having an affinity for printing ink are added to a photosensitive composition. For example, Japanese Patent Publication 62-60701
Japanese Patent Laid-Open No. 63-20424 discloses a technique in which a high molecular compound which is lipophilic and has poor compatibility with a main polymer compound is added to form a layer structure which is more lipophilic toward the surface.
Japanese Unexamined Patent Publication No. 8 discloses a technique of adding a condensation polymerization resin obtained by condensing a substituted phenol and an aldehyde.

[0005]

However, it has become clear that various disadvantages occur when the photosensitive composition having improved ink receptivity of printing ink is used as a lithographic printing plate. For example, as a large number of prints are made, the amount of printing of the resist is reduced, and the oil sensitivity on the surface is lost. As a result, there is a problem that an extreme inking defect of the printing ink, that is, a poor printing durability is caused. Further, the condensation-polymerized resin has a problem that it may be deposited in the photosensitive layer as an aggregate and cause coating failure, probably because of the coupling reaction with the diazo resin. Therefore, the purpose of the present invention is to
An object of the present invention is to provide a photosensitive lithographic printing plate which has good initial ink receptivity, does not cause gum loss phenomenon, and does not cause imperfections in ink replenishment of printing ink even when printing a large number of sheets.
Another object of the present invention is to provide a photosensitive lithographic printing plate excellent in development stability that does not cause development failure even when treated with a tired developer, that is, does not cause stains during printing.

[0006]

The present invention is directed to a diazo resin,
In a photosensitive lithographic printing plate having a photosensitive layer containing a polymer compound and an oil sensitizer, 0.05 to 20% by weight of t-butyl-substituted polyvinylphenol resin is used as the oil sensitizer.
The present invention provides a photosensitive lithographic printing plate characterized by containing it.

Examples of the diazo resin include a diazo monomer having a 4-diazodiphenylamine skeleton, a 4-diazodiphenylether skeleton or a 4-diazodiphenylsulfide skeleton, an aldehyde or an aldehyde having a carboxyl group, and in some cases, the above-mentioned aldehydes. Examples thereof include a cocondensation product of a divalent aromatic compound that can be condensed with. Specific examples of the diazo monomer include 4-diazodiphenylamine, 4'-hydroxy-4-diazodiphenylamine, 4'-methoxy-4-diazodiphenylamine, 4'-ethoxy-4-diazodiphenylamine, 4'-methyl. -4-diazodiphenylamine, 4 '
-Ethyl-4-diazodiphenylamine, 4-diazo-
3-methoxydiphenylamine, 3-methyl-4-diazodiphenylamine, 3-ethyl-4-diazodiphenylamine, 3'-methyl-4-diazodiphenylamine, 3-ethoxy-4-diazodiphenylamine, 4-
Examples thereof include diazodiphenyl ether, 4'-methoxy-4-diazodiphenyl ether, 4'-carboxy-4-diazodiphenyl ether, 4-diazodiphenyl sulfide, 4'-methyl-4-diazodiphenylsulfide. Specific examples of the aldehydes include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, glyoxylic acid and the like. Further, instead of the above aldehydes, 4,
It is also possible to condense with 4'-dimethoxymethyldiphenyl ether.

Specific examples of the aromatic compound include phenol, o, m, p-cresol, xylenol, resorcin, o, m, p-methoxyphenol, catechol, p-hydroxyethylphenol, naphthol, pyrogallol, hydroquinone, Bisphenol A, bisphenol S, o, m, p-chlorophenol, cumylphenol, benzoic acid, salicylic acid, p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, p-methoxybenzoic acid, p-phenoxybenzoic acid, Cinnamic acid, 4-hydroxycinnamic acid, methyl cinnamate, ethyl cinnamate, p
-Methyl hydroxycinnamate, ethyl p-hydroxycinnamate, p-nitrocinnamic acid, p-methoxycinnamic acid,
Cinnamylidene acetic acid, p-hydroxycinnamylidene acetic acid, cinnamylidene methyl acetate, cinnamylidene ethyl acetate, p-hydroxycinnamylidene methyl acetate, p-
Ethyl hydroxycinnamylidene acetate, p-nitrocinnamylidene acetic acid, p-methoxycinnamylidene acetic acid,
2,4-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone and the like can be mentioned.

The diazo resin is preferably used in the form of an organic salt or an inorganic salt. As an example of the organic compound which reacts with the diazo resin to form an organic salt, Japanese Patent Publication No.
0-2203, Japanese Patent Publication No. 41-6813, Japanese Patent Publication No. 47
Nos. 1167 and the like, specifically benzenesulfonic acid, p-toluenesulfonic acid, 2,5-xylenesulfonic acid, linear or side chain dodecylbenzenesulfonic acid (commonly known as dodecylbenzenesulfonic acid), Two
-Methoxy-4-hydroxy-5-benzoylbenzenesulfonic acid, methanyl yellow, 2-chlorotoluene-4
-Sulfonic acids and their alkali metal salts, alkaline earth metal salts, ammonium salts and the like. Further, examples of the inorganic compound which reacts with the above-mentioned diazo resin to form an inorganic salt include JP-B-40-2203 and JP-A-5-2053.
4-98613, U.S. Pat. No. 4,093,465 and the like, specifically, borofluoric acid, hexafluorophosphoric acid, phosphotungstic acid, thiocyanic acid,
And alkali metal salts and ammonium salts thereof. The content ratio of the diazo resin to the photosensitive layer is preferably 1 to 60% by weight, more preferably 5 to 40%.
% By weight.

The above-mentioned polymer compound is preferably a water-insoluble, alkali-soluble or swellable polymer. Examples of such polymers include copolymers having the following structural units (1) to (8) as their structural units. (1) A monomer having an aromatic hydroxyl group; for example, N-
(4-hydroxyphenyl) acrylamide or N-
(4-hydroxyphenyl) methacrylamide, N-
(P-hydroxyphenyl) maleimide, p-isopropenylphenol, o, m, p-hydroxystyrene,
o, m, p-hydroxyphenyl acrylate or methacrylate: (2) Monomer having aliphatic hydroxyl group; for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxy acrylate, 2-hydroxy-3-. Phenoxymethacrylate: (3) α, β-unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic anhydride: (4) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate,
(Substituted) alkyl acrylates such as hexyl acrylate, octyl acrylate, lauryl acrylate, glycidyl acrylate: (5) methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate,
(Substituted) alkyl methacrylates such as amyl methacrylate, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate and glycidyl methacrylate: (6) acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-ethyl acrylamide, N-hexyl methacryl Amides, acrylamides such as N-cyclohexylacrylamide, N-hydroxyethylacrylamide and N-phenylacrylamide, or methacrylamides: (7) Styrenes such as styrene, α-methylstyrene, chloromethylstyrene: (8) N-vinylpyrrolidone , N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile, etc .: the above alkali-soluble polymer It is to, (1) to
It is also possible to use a copolymer obtained by copolymerizing a monomer copolymerizable with the monomer (8). Further, a copolymer obtained by copolymerizing with the above-mentioned monomer modified with, for example, glycidyl methacrylate or glycidyl acrylate may be used, but the copolymer is not limited thereto.

Further, if necessary, the above-mentioned polymers include polyvinyl butyral resin, polyurethane resin, alkali-soluble polyurethane resin, polyamide resin, alkali-soluble polyamide resin, epoxy resin, polyvinylpyrrolidone, ethylene-vinyl acetate copolymer, styrene-
Maleic anhydride copolymer and its partially esterified product,
Polyvinylphenol resin, phenol or cresol-formaldehyde resin, t-butylphenol-formaldehyde resin and the like may be added. The content ratio of the polymer compound to the photosensitive layer is preferably 5 to 95.
%, More preferably 10 to 90% by weight.

The oil sensitizer is a t-butyl-substituted polyvinylphenol resin and is represented by the following general formula (I).

[Chemical 1] (N is an integer of 2 or more.) The content of the t-butyl-substituted polyvinylphenol resin in the photosensitive layer is 0.05 to 20% by weight, more preferably 0.1 to 15% by weight, and further preferably 0. 1-1
It is 0% by weight. If it is less than 0.05% by weight, the ink receptivity will be poor, and if it exceeds 20% by weight, the developability will be poor.

In addition to the above-mentioned components, the photosensitive layer of the present invention may further contain a colorant, a storage stabilizer, a plasticizer, a surfactant and the like, if necessary. As the colorant, a dye, a pigment or the like can be used.
Specific examples of the dye include crystal violet,
Mention may be made of malachide green, Victoria blue, methylene blue, ethyl violet, rhodamine B and the like, and basic oil dyes which are derivatives thereof. Such dyes are available in Victoria Pure Blue BO
H (Hodogaya Chemical Co., Ltd.), Oil Blue 613
(Manufactured by Orient Chemical Industry Co., Ltd.), Permanent Blue # 47 (manufactured by Daido Chemical Industry Co., Ltd.) and the like. Specific examples of the above pigment include phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone red, and indanthrene blue. As its commercial product,
Examples include Neozapon Blue FLE (manufactured by Bardish Aniline Co., Ltd.), Oil Blue BOS (manufactured by Orient Chemical Industry Co., Ltd.), and Spiron Blue GNH (manufactured by Hodogaya Chemical Co., Ltd.). The content of the dye or pigment in the photosensitive layer is preferably 0.1 to 5.0% by weight, more preferably 0.5 to 4.0% by weight.

Examples of the storage stabilizer include phosphoric acid, oxalic acid, citric acid, malic acid, tartaric acid, mandelic acid, benzophenone derivatives and the like. The content of these storage stabilizers is preferably 2 to 20 with respect to the diazo resin salt.
%, More preferably 5 to 15% by weight. In the present invention, a plasticizer or a surfactant may be added for the purpose of improving the coatability of the photosensitive layer and improving the adhesion of the photosensitive layer to the support. Examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, diisononyl phthalate, ethylphthalylethyl glycol, dimethyl. Examples include isophthalate. The content of the plasticizer in the photosensitive layer is preferably about 0.5 to 3.0% by weight, more preferably 0.6 to 2.0% by weight. As the surfactant, sorbitan monooleate, sorbitan stearate, sorbitan monostearate,
Examples thereof include sorbitan sesquioleate, sorbitan monolaurate, polyoxyethylene nonylphenyl ether, and polyoxyethylene octylphenyl ether.

In the present invention, a photosensitive composition containing the above components is added to methanol, ethanol, propanol, acetone, methylene chloride, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, NN-dimethylformamide, dimethyl sulfoxide, ethylene glycol monomethyl. Sensitization by dissolving in a suitable solvent such as ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl lactate alone or in combination of two or more Prepare the liquid. Then, the prepared photosensitive solution is applied to the surface of the support and dried to obtain the photosensitive lithographic printing plate of the present invention.

The above-mentioned photosensitive liquid can be applied by a conventionally known method such as spin coating, extrusion coating, wire bar coating, roll coating, air knife coating, dip coating, curtain coating and the like. The coating amount of the above-mentioned photosensitive solution varies depending on the use, but the solid content of the photosensitive lithographic printing material is preferably 0.1 to 10 g / m ² .
The support of the photosensitive lithographic printing plate of the present invention, paper, plastic film, or copper, zinc, aluminum,
A metal plate such as stainless steel or a composite material in which two or more of these are combined can be used. Among these, especially brushed or ball-polished aluminum plates,
An aluminum plate that has been brush-polished and then anodized, an aluminum plate that has been electrolytically polished and then anodized, or an aluminum plate that has been subjected to a combination of these processes is preferable. The aluminum plate which has been subjected to such a pretreatment is further subjected to a chemical conversion treatment with a single liquid or a mixed liquid of alkali silicate, sodium phosphate, sodium fluoride, zirconium fluoride, alkyl titanate, trihydroxybenzoic acid or the like as a post treatment. , Boehmite treatment or coating treatment with an aqueous solution of strontium acetate, zinc acetate, magnesium acetate, calcium benzoate, etc.
Polyvinylpyrrolidone, polyaminesulfonic acid, polyvinylphosphonic acid, polyacrylic acid, polymethacrylic acid,
It is also possible to perform a coating treatment with poly-2-hydroxyethyl acrylate or the like.

In the present invention, for the purpose of improving the vacuum adhesion to the film, a mat layer is provided on the photosensitive layer, an organic solvent-insoluble matting agent or an organic solvent-insoluble polymer compound is contained in the photosensitive layer. Can also be included.
As a light source for irradiating the photosensitive lithographic printing plate of the present invention with an actinic ray, a mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, a carbon arc lamp, an argon laser, a helium / cadmium laser, an excimer laser or the like can be used. it can. The developer for the photosensitive lithographic printing plate of the present invention, sodium hydroxide,
Alkaline such as potassium hydroxide, sodium silicate, sodium metasilicate, sodium orthosilicate, sodium phosphate tribasic, sodium phosphate dibasic, sodium octanoate, monoethanolamine, diethanolamine, triethanolamine, tetramethylammonium hydroxide An aqueous solution of the compound (alkaline aqueous solution) may be mentioned.

If necessary, an activator and / or a solvent may be added to the above alkaline aqueous solution.
An anionic surfactant or an amphoteric surfactant can be used as the above-mentioned surfactant. Examples of the anionic surfactant include sulfuric acid esters of alcohol having 8 to 22 carbon atoms (for example, polyoxyethylene alkyl sulfate soda salt), alkylaryl sulfonates (for example, sodium dodecylbenzenesulfonate, polyoxyethylene dodecylphenyl). Sulfate soda salt, sodium alkylnaphthalene sulfonate, sodium naphthalene sulfonate, formalin condensate of sodium naphthalene sulfonate), sodium dialkyl sulfosuccinate, alkyl ether phosphate, alkyl phosphate ester and the like can be used. The amphoteric surfactant is preferably an alkyl betaine type or an alkyl imidazoline type. Alcohols and ethers are preferable as the above-mentioned solvent, but 10% in water (20 ° C)
A solvent that does not dissolve by more than 100% is preferable, and examples of this type of solvent include benzyl alcohol, DL-α-phenylethyl alcohol, 2-phenylethyl alcohol, phenyl glycol, and phenyl cellosolve. Water-soluble sulfites such as sodium sulfite, potassium sulfite, lithium sulfite and magnesium sulfite can be further added to the alkaline aqueous solution.

[Examples] The present invention will be described in more detail with reference to Synthesis Examples and Examples, but the present invention is not limited thereto.

Synthesis example: 1. Polymer compound No. Synthesis of 1; 200 g of ethylene glycol monomethyl ether as a reaction solvent and a mixture having the following composition were added to a 1-liter four-necked flask equipped with a stirrer and a cooling tube. After heating the inside of the flask to 90 ° C., 0.4 g of 2,2′-azobis (2-methylbutyronitrile) was added and the atmosphere was replaced with nitrogen gas.
The mixture was stirred at 0 ° C for 5 hours. After completion of the reaction, the reaction mixture was poured into 10 liters of water, filtered and dried. Note 2-hydroxy-3-phenoxypropyl methacrylate 20 g 2-hydroxyethyl methacrylate 30 g methacrylic acid 5 g methyl methacrylate 20 g acrylonitrile 25 g 2. Polymer compound No. Synthesis of Polymer Compound No. 2 except that a mixture having the following composition is used. Polymerization was carried out under the same conditions as in Polymer No. Got 2. Description p-isopropenylphenol 40 g 2-hydroxyethyl methacrylate 15 g Methacrylic acid 5 g Methyl methacrylate 10 g Acrylonitrile 30 g

Examples 1 and 2 and Comparative Examples 1 to 3: An aluminum plate (material 1050) having a thickness of 0.24 mm and a width of 1000 mm was alkali-degreased, and then a nylon brush was used to clean the surface with a water suspension of permistone. Polished and then thoroughly washed with water. Then, a caustic soda solution of 20% at 70 ° C. is flowed over for 5 seconds to etch the surface with 3 g / m ² and then washed with running water, hydrochloric acid (35 g / liter), boric acid (20 g / liter) and aluminum ion ( 20 g / l) in electrolyte at 45 ° C for 30 A
Electrolytic polishing was carried out at a current density of / dm ² for 30 seconds, followed by washing with water.
Then, a caustic soda solution of 70 ° C. and 20% is poured over the surface to etch the surface, and the surface is further washed with water.
Anodic oxidation treatment in 10% sulfuric acid aqueous solution at ℃,
An oxide film of 2.0 g / m ² was formed. After washing with water, an aqueous solution containing JIS 3 sodium silicate 5%,
It was dipped at 70 ° C. for 10 seconds, washed with water and dried. On the aluminum plate thus obtained, the photosensitive liquid 1 having the following composition
Nos. 5 to 5 were applied so that the coating film weight after drying was 1.8 g / m ² and dried. Example 1 (photosensitive liquid 1); Polymer compound No. 1 3.0 g 4- condensate of diazodiphenylamine and formaldehyde 2-methoxy-4-hydroxy-5-benzoylbenzene sulfonate (diazo resin No. 1) 0.3 g t-butyl-substituted polyvinylphenol resin 0.06 g Victoria Pure blue BOH 0.06 g Oxalic acid 0.02 g Ethylene glycol monomethyl ether 60 g Propylene glycol monomethyl ether 30 g N-N-dimethylformamide 10 g Example 2 (photosensitive solution 2); 2 3.0 g 2-Methoxy-4-hydroxy-5-benzoylbenzenesulfonate (diazo resin No. 2) of a co-condensate of 4-diazodiphenylamine, p-hydroxybenzoic acid and formaldehyde 0.3 g t-butyl substitution Polyvinylphenol resin 0.06 g Victoria Pure Blue BOH 0.06 g Malic acid 0.02 g Ethylene glycol monomethyl ether 60 g Propylene glycol monomethyl ether 30 g N-N-dimethylformamide 10 g Comparative example 1 (photosensitive solution 3); 1 3.0 g diazo resin No. 1 1 0.3 g Styrene-isobutyl alcohol of maleic anhydride resin Half ester resin 0.06 g Victoria Pure Blue BOH 0.06 g Oxalic acid 0.02 g Ethylene glycol monomethyl ether 60 g Propylene glycol monomethyl ether 30 g N-N-dimethylformamide 10 g Comparative example 2 (photosensitive liquid 4); polymer compound No. 2 3.0 g diazo resin No. 2 0.3 g t-butylphenol-formaldehyde resin 0.06 g Victoria Pure Blue BOH 0.06 g Malic acid 0.02 g Ethylene glycol monomethyl ether 60 g Propylene glycol monomethyl ether 30 g N-N-dimethylformamide 10 g Comparative example 3 (photosensitive solution 5) Polymer compound No. 1 3.0 g diazo resin No. 1 1 0.3 g Victoria Pure Blue BOH 0.06 g Oxalic acid 0.02 g Ethylene glycol monomethyl ether 60 g Propylene glycol monomethyl ether 30 g N-N-dimethylformamide 10 g

In the photosensitive lithographic printing plate thus obtained,
Negative film and Kodak step tablet N
o. 2 was vacuum-adhered and irradiated with ultraviolet rays for 30 seconds at a distance of 1 m using a 2 kW high-pressure mercury lamp, and then a developer No. 2 having the following composition was used. 1 or No. 2 was used for immersion at 25 ° C. for 30 seconds for development to obtain a lithographic printing plate sample. Developer No. 1; potassium silicate 20% aqueous solution 50 g phenyl glycol 40 g isopropyl potassium naphthalene sulfonate 5 g calcium sulfite 2 g water 903 g developer No. 1; 2; JIS No. 3 sodium silicate 25 g Potassium hydroxide 15 g Amogen K (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 1 g Water 1 kg Subsequently, gumming was carried out with gum arabic 8 degree Baume liquid, and the following test was conducted. The results are shown in Table 1. (1) Ink receptivity: Whether or not the ink was uniformly adhered to the image area after printing was evaluated and evaluated according to the following criteria. ○: There is no problem in ink receptivity even when printing several thousand sheets from the first printing. Δ: Ink is deposited on the first printing, but defective deposition occurs after printing several sheets. X: Partial defective inking occurs from the first printing. (2) Developability test; the developer No. 1 and N
o. When 2 is diluted with water twice and developed (3 at 25 ° C
The presence or absence of stains on the non-image area at 0 second) was examined.

[0023]

[Table 1]

As is clear from the results shown in Table 1, the photosensitive printing plate of the present invention has markedly improved ink receptivity and developability.

[0025]

INDUSTRIAL APPLICABILITY The photosensitive lithographic printing plate of the present invention is excellent in initial ink receptivity and developability, does not cause a gum loss phenomenon, and particularly the receptivity of printing ink when a large number of sheets are printed. That is, it has a remarkable effect that the printing durability is excellent. Furthermore, the photosensitive lithographic printing plate of the present invention has excellent development stability.

Claims (1)

[Claims] 1. A photosensitive lithographic printing plate having a photosensitive layer containing a diazo resin, a polymer compound and an oil sensitizer, wherein 0.05 to 20% by weight of t-butyl-substituted polyvinylphenol resin is used as the oil sensitizer. A photosensitive lithographic printing plate characterized by containing it.