JPS6271960A - Photosensitive lithographic printing plate - Google Patents

Abstract

PURPOSE:To form a photosensitive lithographic printing plate which permits an easy printing operation by coating a specific photosensitive compsn. on an aluminum sheet obtd. by subjecting the surface to sand graining by liquid honing then to an anodic oxidation treatment in a phosphoric acid electrolyte. CONSTITUTION:This photosensitive lithographic printing plate is constituted by coating the photosensitive compsn. essentially consisting of a diazo resin and lipophilic high-polymer compd. having a hydroxyl group on the aluminum sheet obtd. by subjecting the surface to sand graining by liquid honing, then to the anodic oxidation treatment in the electrolyte essentially consisting of the phosphoric acid (salt). The diazo resin contains >=20mol%, more preferably 20-60mol% resin which is expressed by formula I and is>=5 n in formula. The lipophilic high-polymer compd. is adequately the lipophilic high-polymer compd. having the hydroxyl group in terms of adhesiveness and developability. The amt. of the coated film is preferably in a 10-40mg/dm<2>, more particularly preferably, 10-30mg/dm<2> range.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a photosensitive lithographic printing plate, and more specifically, an aluminum plate grained by a specific method,
The present invention relates to a photosensitive lithographic printing plate having good printing performance due to a preferable combination with a photosensitive composition having good adaptability to the aluminum plate.

[Conventional technology]

In the lithographic printing method, a hydrophilic area and an oleophilic area are provided on a flat surface, water and ink are simultaneously supplied to these areas, the hydrophilic area receives water and the oleophilic area receives ink, and then the ink is transferred to paper. This is a method of printing. A method for forming a pattern of hydrophilic areas and lipophilic areas in this way is usually to form a photosensitive layer by depositing a lipophilic photosensitive composition on a support having a hydrophilic surface, and then to form a photosensitive layer with a transparent film. A so-called photolithography method is generally used in which an original image is exposed in close contact with the original image, and then the exposed or unexposed areas are dissolved and removed. The printing performance of the lithographic printing plate thus obtained is greatly influenced by the properties of the surface of the support, which will be the non-image area, and the properties of the photosensitive layer film, which will be the image area.If these selections are not appropriate, for example, the following This may cause some inconvenient phenomena. In other words, if the hydrophilicity or water retention of the support surface is insufficient, it is difficult to control dampening water during printing, and when the supply is low, a scumming phenomenon occurs in which ink adheres to non-image areas. If the amount increases, the ink density will decrease and the printing process will become slower.
The disadvantage is that it is difficult to Furthermore, if the lipophilicity of the photosensitive layer coating is insufficient, the printing ink will not adhere to the coating and, therefore, the ink will not transfer well to the printing paper, resulting in printed matter with low density. Furthermore, if the chemical or physical strength of the support surface or photosensitive layer coating is insufficient, or if the adhesion between the support and the photosensitive layer is insufficient, the surface may be damaged by printing a large number of copies. If the surface of the support is damaged, scumming will occur, while if the photosensitive layer film is damaged or peeled off, the transfer of printing ink will no longer occur and the plate will actually lose its value as a printing plate. p1 The printing plate has a low printing durability.

Therefore, as mentioned above, in order to obtain a photosensitive lithographic printing plate with good printing performance, when selecting the support and the photosensitive composition, consider not only the characteristics of both, but also the characteristics of the combination of the two. There is a need.

The aluminum plate used as a support for photosensitive lithographic printing plates can be roughened by mechanical roughening methods such as ball gray/wire grain, brush grain, or honing grain, or by electrochemical roughening methods such as electrolytic graining. The surface is roughened by a psychokinetic method, which is selected from among many surface roughening methods such as chemical or chemical roughening methods.In order to further improve water retention and mechanical strength of the surface, an aqueous solution of sulfuric acid, phosphoric acid, etc. It is anodized and used as a support for photosensitive planographic printing plates.

Aluminum plates used in photosensitive lithographic printing plates having grains suitable for printing plates are manufactured by a combination of the above-mentioned surface roughening method and anodizing treatment method.

Conventionally, in terms of cost, grain uniformity, and printing performance,
Since there are no particularly serious drawbacks, the aluminum support to which the light-sensitive composition mainly composed of diazo resin and lipophilic polymer compound is coated is prepared by adding (1) brush grain to -m in sulfur. (2) Brush grain - anodic oxidation in phosphoric acid, (3)! It was produced by anodic oxidation of dissolved grains in sulfuric acid. However, method (1) O has uneven surface roughening, is prone to staining as a printing plate, and has a low printing durability l/%, and method (2) has a large printing durability. However, method (3), which tends to cause stains during printing, tends to have low printing durability, although it does not easily cause background stains.

[Problems to be Solved by the Invention] Each of the drawbacks of the above-mentioned supports can be improved by appropriately selecting a photosensitive composition to be layered thereon, but printing durability and staining during printing can be improved. At present, a photosensitive lithographic printing plate that fully satisfies both of these difficulties has not been obtained.

An object of the present invention is to provide a photosensitive lithographic printing plate that allows easy control of dampening water supply during printing, and therefore facilitates printing operations.

Another object of the present invention is to provide a photosensitive lithographic printing plate that is less likely to cause scumming during printing and has extremely high printing durability.

[Means for solving problems]

To summarize the present invention, the present invention relates to a photosensitive lithographic printing plate, in which the surface is grained by liquid honing and then placed in phosphoric acid (salt) or an electrolytic solution containing phosphoric acid (salt) as a main component. It is characterized in that a photosensitive composition whose main components are a diazo resin and a lipophilic polymer compound having a hydroxyl group is coated on an aluminum plate obtained by anodizing the aluminum plate.

The present invention will be explained in detail below.

Materials for the aluminum plate used in the present invention include pure aluminum and aluminum alloys;
It may contain trace amounts of silicon, iron, copper, zinc, manganese, magnesium, chromium, bismuth, calcium, indium, gallium, copper, nickel, etc., but in any case, the purity of aluminum is 95% or more. is preferred.

Such an aluminum plate is practically selected from α1 to (L5-) depending on the strength, yield strength, elongation, etc. required when it is mounted on a printing machine as a lithographic printing plate.

The liquid honing method of the present invention for roughening the aluminum plate is a method in which a fine abrasive is suspended in a liquid and a slurry is violently sprayed onto the aluminum plate surface to provide graining. As the abrasive used here, alumina, carborundum, etc. can be adopted.

A preferred embodiment of the liquid honing method is JP-A-51-77
As disclosed in Japanese Patent Publication No. 405 and Japanese Patent Publication No. 54-42282, the first step is liquid honing using a relatively coarse abrasive, and then the second step is using a relatively fine abrasive. This is a step-by-step liquid honing process. In this case, the particle size of the abrasive used in the first stage of liquid honing is appropriate since the above-mentioned primary grain size is achieved when the particle size is 150 to 280 mesh. The particle size of the abrasive is 100
It is appropriate to set it to 0 to 3000 meshes.

When performing liquid honing treatment, it is desirable to perform degreasing and cleaning in advance. Degreasing treatments include solvent degreasing, which uses petroleum-based solvents or chlorinated hydrocarbons such as trichlorethylene and perchloroethylene to remove dirt, and emulsification of nonionic surfactants, solvents such as trichlorethylene and kerosene, and water. Emulsion degreasing using solutions,
Examples include alkaline degreasing, which involves boiling in a treatment solution containing alkaline chemicals, and electrolytic degreasing.

Since smut is generated on the surface of a roughened substrate, it is desirable to remove the smut by etching the surface with acid or alkali. As the acid, for example, sulfuric acid, heptanoic acid, phosphoric acid, nitric acid, hydrochloric acid, etc. are used, and as the alkali, sodium hydroxide, potassium hydroxide, tribasic sodium phosphate, tribasic potassium phosphate, aluminic acid, etc. are used. Sodium, sodium metasilicate, sodium carbonate, etc. are used.

The aluminum plate used in the present invention is then prepared using phosphoric acid (
Anodized in an electrolyte containing mainly phosphoric acid (salt) or phosphoric acid (salt). For example, an aluminum plate is coated with 10 to 50 ftqb of phosphorus, preferably 20 to 40 ftqb of phosphorus.
! In an aqueous solution containing phosphoric acid and a mixed acid with other acids such as sulfuric acid and oxalic acid in an amount of 25% by weight or less, preferably 10% by weight or less of the total acid, for example, sulfuric acid, oxalic acid, etc., at a bath temperature of 1.
Current density (
L 2-10 A/ (1m", preferably 1-7
A/mu: 10 seconds to 10 minutes, preferably 20 seconds to
In the range of 3 minutes, the amount of the anodized layer obtained is suitably 5 to 70 IQ/eLm'', preferably 10 to 40 IQ/am''.

The anodized aluminum substrate is usually further heated at 10 to 100°C in water or a weak acid or weak alkali aqueous solution.
, 10 to 600 seconds. after that,
Hydrophilic treatment is applied.

Examples of the hydrophilic treatment include hot water sealing and sodium silicate treatment, but sodium silicate treatment is preferable from the viewpoints of adhesion, diazo residue, and developability.

The sodium silicate treatment is carried out by immersion in a sodium metasilicate solution having a concentration of α1 to 5.0 at a temperature of 50° C. to 95° C. for 10 seconds to 5 minutes.

Preferably, it is then treated by immersion in water at 60° C. to 100° C. for 10 seconds to 5 minutes.

The photosensitive composition of the present invention to be coated on the aluminum plate has a hydroxyl group-containing lipophilic polymer compound and a diazo resin as main components.

The diazo resin is preferably a condensate of a substituted or unsubstituted op-diazodiphenylamine and an aldehyde, and the anion is a Lewis acid such as PF6 or PF4. A diazo resin containing 20 or more moles, preferably 20 to 60 moles of a resin shown in the formula and where n is 5 or more is preferred.

(In the formula, 11.R'' and R3 represent hydrogen, an alkyl group or an alkoxy group, R represents hydrogen, an alkyl group or a phenyl group, X represents PIP or 1BIF4, and n represents 1-
200) In addition, for example, those described in Japanese Patent Publication No. 47-1167 or US Pat. No. 5,500,509 in which the anion is an organic acid can also be used.

The lipophilic polymer compound is preferably a lipophilic polymer compound having a hydroxyl group from the viewpoint of adhesiveness and developability.

The coating amount is preferably 10-40*/dm", 10-S
A range of Oq/l1m'' is particularly suitable.

The lipophilic polymer compound having a hydroxyl group used in the present invention may be derived from monomers such as acrylamides, methacrylamides, acrylic esters, or methacrylic esters having a hydroxyl group as shown below. Examples include copolymers containing structural units and usually having a molecular weight of 500 to 200,000 units.

(1) A monomer having an aromatic hydroxyl group, such as N
-(4-Hydroxyphenylonacrylamide)"
h N-('-hydroxyphenyl]methacrylamide, O-* m-+ i'-hydroxystyrene,
o +, m +, p-hydroxy722acrylate or methacrylate (2) Monomers having aliphatic hydroxyl groups, such as 2-hydroxy7ether acrylate or 2-hydroxyethyl methacrylate Other monomers to be copolymerized include (1) αβ-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride (2) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, acrylic acid (Substituted) alkyl acrylates such as octyl, 2-chloroethyl acrylate, 2-hydroxyethyl acrylate, grindyl acrylate, N-dimethylaminoether acrylate (3) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate,
amyl methacrylate, cyclohexyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, glitadyl methacrylate,
(Substitution) of N-dimethylaminoether methacrylate, etc.
Alkyl methacrylate (41 acrylamide, methacrylamide, N-methylol acrylamide, N-methylolmethacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-chlorohexyl acrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, - Acrylamides or methacrylamides such as nitrophenyl acrylamide and N-ethyl-N-phenylacrylamide (5) Ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, flobyl vinyl ether, phthyl vinyl ether, octyl vinyl ether, phenyl vinyl ether (6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate, and vinyl benzoate (7) Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene (8) Methyl vinyl ketone, ethyl vinyl ketone,
Vinyl ketones such as propyl vinyl ketone and phenyl vinyl ketone (9) Olefins such as ethylene, fluoropylene, imbutylene, phthadiene, imprene, etc. N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacryl Examples include nitrile, but any other monomer that can be copolymerized with a hydroxyl group-containing monomer may be used, and the present invention is not limited thereto. In addition to these, polyvinyl butyral resin, polyurethane resin, polyamide resin, epoxy resin, novolac resin, natural resin, etc. may be added as necessary.

The lipophilic polymer compound having a hydroxyl group used in the present invention usually contains 40 to 99 xit in the solid content of the photosensitive composition.
%, preferably 50 to 95% by weight. Further, the diazo resin is usually contained in an amount of 1 to 60% by weight, preferably 3 to 30% by weight.

In order to further improve the performance of the photosensitive composition of the present invention, the following nine various known additives can be added.

(1) Dye for the purpose of visualizing images (2)
Fluorine surfactants and alkyl ethers to improve coating properties (3) Plasticizer C4J to impart flexibility and abrasion resistance to the coating film Sensitizing agent (5) Stabilizer The amount of these additives is Generally, α01 to 30% by weight based on the total solid content.

The developer used in the development of the photosensitive lithographic printing plate according to the present invention may be any known developer, but the following are preferred. That is, the developer for developing the photosensitive printing plate according to the present invention may be water or an aqueous solution containing a specific organic solvent and/or alkaline agent. Here, the specific organic solvent is one that can dissolve or swell the non-exposed area (non-image area) of the above-mentioned photosensitive composition layer when contained in the developer, and that is soluble in water at room temperature (20°C). Refers to an organic solvent having a solubility of 10% by weight or less in 10% by weight or less.Such organic solvents only need to have the above-mentioned characteristics, and are not limited to the following, but include: Examples include ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethylene glycol motubutyl acetate,
Carbo/acid esters such as butyl lactate, butyl levulinate; ethyl butyl ketone, methyl imptyl ketone,
Ketones such as 7-chlorhexanone; ethylene glycol motuptyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, benzyl alcohol, methyl amyl alcohol, n-7 methyl alcohol, Methyl amyl alcohol and other alcohols;
These include alkyl-substituted aromatic hydrocarbons such as xylene; and more chlorogenated hydrocarbons such as methylene dichloride, ethylene dichloride, and monochlorobenzene. One or more of these organic solvents may be used. Among these organic solvents, ethylene glycol monophenyl ether and benzyl alcohol are particularly effective. Secondly, the f content of these organic solvents in the developing solution is generally from 1 to 20% by weight, and more preferable results are obtained especially when it is from 2 to 10% by weight.

On the other hand, the alkaline agents contained in the developer include sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium or ammonium salts of dibasic or tertiary phosphoric acid, and metasilicon. Inorganic alkaline agents (B) such as sodium acid, sodium carbonate, ammonia, mono-, di- or trimethylamine, mono-, di- or triethylamine, mono- or diinoprobylamine,
Examples thereof include organic amine compounds such as n-butylamine/mono-, di-, or triethanolamine, mono-, di-, or tri-impropanolamine, ethyleneimine, and ethylenediamine.

The content of these alkaline agents in the developer is usually α0
5 to 4 weights, preferably α5 to 2 weights.

Furthermore, in order to further improve storage stability, printing durability, etc., it is preferable to include a water-soluble sulfite in the developer. Such water-soluble sulfites are preferably alkali or alkaline earth metal salts of sulfite, such as sodium sulfite, potassium sulfite, lithium sulfite, magnesium sulfite, and the like. The Jlr1 content of these sulfites in the developer composition is usually 0.05 to 4% by weight, preferably 111 to 1% by weight.

Certain solubilizers may also be included to aid in the dissolution of the organic solvents mentioned above in water. In order to achieve the desired effects of the present invention, such solubilizers include:
(organic solvent used) water-soluble, low-molecular alcohol,
It is better to use ketones. Furthermore, anionic activators, amphoteric activators, etc. can also be used. Examples of such alcohols and ketones include methanol, ethanol, propatool, phthanol, acetone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methquinbutanol, ethoxybutanol, and 4-methoxybutanol. , N-methylpyrrolidone, etc. are preferably used. Further, as the activator, sodium inpropylnaphthalenesulfonate, sodium n-butylnaphthalenesulfonate, sodium N-methyl-N-pentadecylaminoacetate, sodium lauryl sulfate, etc. are preferable. There is no particular restriction on the amount of solubilizers such as alcohols and ketones used, but it is generally preferable to use the amount of solubilizing agents such as alcohols and ketones at about 50 weight i1 or less based on the entire developer.

After the photosensitive lithographic printing plate of the present invention has been imagewise exposed, if it is brought into contact with the developer described above or rubbed, it becomes photosensitive after 10 to 60 seconds at room temperature to 40°C. The photosensitive composition in the non-exposed areas of the photosensitive composition layer is completely removed without adversely affecting the exposed areas of the photosensitive composition layer.

Examples of producing grain, diazo resin, and polymer O used in the present invention are shown below.

(Manufacture of sand grains) Manufactured six types of aluminum plates with different grinding and anodizing conditions. Table 1 shows their manufacturing conditions.

All aluminum plates (thickness α3) were cleaned with trichlorethylene, degreased, polished, anodized, and then soaked in 1% sodium metasilicate solution.
Sodium silicate treatment was performed by immersing at 5°C for 3 minutes, followed by immersion in hot water at 90°C for 2 minutes.

(Synthesis of Polymer 1) X-(a-hydroxyphenyl)methacrylamide 1[
2 for 1 bite, 25 for acrylonitrile? , 60 f of ethyl acrylate, 5 f of methacrylic acid, and 1.642 f of azobisinobutyronitrile were dissolved in 112 dK of acetone-methanol 1:1 mixed solvent, and the mixture was purged with nitrogen and then heated at 60° C. for 8 hours.

After the reaction was completed, the reaction solution was poured into a container containing water 5, and the resulting white precipitate was removed and dried to obtain 909 of Polymer 1.

When the molecular weight of this polymer was measured by chromatography (hereinafter abbreviated as GPO), the weight average molecular weight was 50,000 a.

(Synthesis of polymer 2) 2-Hydroxyethyl methacrylate) 45 f.

Acrylonitrile 10t, ethyl methacrylate) 45
f, jl'ri'Jke, 2? and 1.2 foilN
The R-benzoyl mixture was added dropwise to ethylene glycol monomethyl ether 3002 heated to 100°C over 2 hours. After dropping, add 5000 ethylene glycol monomethyl ether and benzoyl peroxide α3? was added and allowed to react for 4 hours. After the reaction was completed, the mixture was diluted with methanol, water 5 was poured into the mixture with stirring, and the resulting white precipitate was removed and dried to obtain 939 of Polymer 2.

When the molecular weight of this polymer was measured by GPC, the weight average molecular weight was &50,000.

(Synthesis of Polymer 3) Methyl methacrylate 602, acrylonitrile S Ot
, 102% of methacrylic acid and 1.52% of azobisinbutyronitrile were dissolved in 200t of methyl cellosolve and polymerized for 4 hours at 80°C while passing nitrogen through the solution. This reaction mixture was added dropwise into 5 L of water, and the resulting white precipitate was collected and dried to obtain Polymer 3.

When the molecular weight of this polymer was measured by GPC, i
-a average molecular weight was 60,000.

(Synthesis of Polymer 4) Polymer 4 was obtained by polymerizing 2-hydroxyethyl methacrylate 45?, acrylonitrile 20t, methyl methacrylate) 30F, and methacrylic acid 5t in the same manner as in the synthesis example of polymer 3.

When the molecular weight of this polymer was measured using GPO, the weight average molecular weight was 63,000.

(Synthesis of diazo resin-1) p-diazodiphenylamine sulfate 14.5 r (5o
mol) was dissolved in 4.0.9F concentrated sulfuric acid under water cooling. To this reaction solution, t 2 t (40 mmol) of paraformaldehyde was slowly added dropwise. At this time, the addition was carried out so that the reaction temperature did not exceed 10°C. Thereafter, stirring was continued for 2 hours under water cooling.

This reaction mixture was dropped into 500 d of ethanol under water cooling, and a precipitate was formed. Filtered. After washing with ethanol, this precipitate was dissolved in 100-m pure water, and to this solution was added a cold concentrated aqueous solution in which 6.8 t of zinc chloride was dissolved. The resulting precipitate was filtered, washed with ethanol, and washed with 150W1t.
was dissolved in pure water. To this liquid was added a cold concentrated aqueous solution in which 82 ammonium hexafluorophosphate was dissolved. The resulting precipitate was washed with water and then dried at 50° C. for 1 day to obtain diazo resin-1.

When the molecular weight of this diazo resin-1 was measured by GPO, it was found that about 35 moles of pentamer or more were involved.

(Synthesis of diazo resin-2) Synthesis was performed in the same manner as diazo resin-1, and 2-hydroxy-4-
Diazo resin-2 was obtained by treatment with an aqueous solution in which methoxy-benzophenone-5-sulfonic acid 152 was dissolved.

When this diazo resin-2 was measured by GPC, it was found that 5
There were about 52 moles of 11 moles or more.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Examples 1 to 3, Comparative Examples 1 to 6 A photosensitive solution having the composition shown in Table 2 was applied to the aluminum plate obtained as described above using a whirler, and dried at 850% for 3 minutes. A photosensitive lithographic printing plate shown in Table 3 was obtained.

Table 2 Photosensitive solution prescription table 3 Photosensitive planographic printing plate The obtained photosensitive planographic printing plate was exposed for 30 seconds from a distance of 60°C with a 5 KW ultra-high pressure mercury lamp, and then heated at 25°C using the following developer. , and was developed for 45 seconds to obtain a lithographic printing plate.

Developer Benzyl Alcohol 509 Triethanolamine 152 Sodium Sulfite
5 Tatsutilnaphthalene sulfonate
25? water 1
The obtained lithographic printing plate 000F was printed on high-quality paper using a sheet-fed offset printing machine, and tests for printing durability and printing stain were conducted. The results are shown in Table 4.

Table 4 Printing durability test and stain test Tatami printing machine Hamada Star ODX 900 (newly manufactured by Hamada Seisaku) ■ For the stain test, dampening was carried out at a certain point during printing under standard conditions in a printing room at 22°C and 62% relative humidity. 20 water supply
% cut and printed, and the number of sheets of clean printed paper obtained is shown.

Table 4 shows that the printing plate of the present invention has high printing durability and is less likely to cause background staining during printing.

〔Effect of the invention〕

Claims (1)

[Claims] 1. On an aluminum plate obtained by graining the surface by liquid honing and then anodizing in phosphoric acid (salt) or an electrolytic solution containing phosphoric acid (salt) as the main component, 1. A photosensitive planographic printing plate coated with a photosensitive composition containing a diazo resin and a lipophilic polymer compound having a hydroxyl group as main components. 2. The polymer compound is a polymer compound containing a structural unit derived from a monomer selected from the group consisting of hydroxyl group-containing acrylamides, methacrylamides, acrylic esters, and methacrylic esters. A photosensitive lithographic printing plate according to claim 1. 3. Claim 1, wherein the diazo resin is a condensate of substituted or unsubstituted p-diazodiphenylamine and aldehydes, and the anion is PF_6 or BF_4.
The photosensitive lithographic printing plate described in Section 1. 4 The diazo resin has the following general formula I: ▲There are mathematical formulas, chemical formulas, tables, etc.▼... [I] (In the formula, R^1, R^2, and R^3 are hydrogen, an alkyl group, or an alkoxy group. , R represents hydrogen, an alkyl group, or a phenyl group, X represents PF_6 or BF_4, and n
represents a number from 1 to 200), and n in the formula
2. The photosensitive lithographic printing plate according to claim 1, which contains 20 mol% or more of a resin having 5 or more.