JPH06103390B2 - Photosensitive lithographic printing plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photosensitive lithographic printing plate, and more specifically, it has high film strength, high printing durability, good storage stability, and good image reproducibility. A photosensitive lithographic printing plate.

[Conventional technology]

Conventionally, a diazo resin obtained by reacting an aromatic diazonium salt, for example, a diphenylamine-4-diazonium salt, with an active carbonyl compound, for example, formaldehyde, is known. Particularly in the printing field, it is widely used as a photosensitive material for plate making of lithographic plates for offset printing by utilizing the change in solubility due to photolysis of diazo resin.

An offset printing plate can be obtained by mixing a diazo resin with a binder or the like and applying it to a hydrophilic metal, paper, preferably aluminum or the like. In this plate, the exposed area is cured by imagewise exposure and becomes insoluble in the developing solution. By treating this with the developing solution, a hydrophilic part and a lipophilic part are obtained on the plate surface, and water and fatty ink are removed. Can be used to print.

The photosensitive substance consisting of a polymer compound and a diazo compound is
It is known that compared with a diazo compound alone, it shows excellent performance such as the need for a Rucker plate or the like later and a stable printing plate being obtained.

Although various types of polymer compounds have been investigated, hydrophilic polymer compounds have excellent developability and compatibility with diazo resins, but have poor storage stability and poor oil sensitivity and are practically used. There is a problem. On the other hand, when the polymer compound is lipophilic, the storage stability and oil sensitivity are excellent, but the developability is particularly poor with an aqueous developer (JP-A-56-4144,
54-98614).

Various studies have also been conducted on diazo resins. For example, in Japanese Examined Patent Publication No. 47-1167 or U.S. Patent No. 3300309,
Organic salts such as organic sulfonates are described as anions of diazo. Further, JP-A-54-98613 describes a halogenated Lewis acid salt as an anion of diazo.

Further, in recent years, from the viewpoint of workability and the like, improvement in printing durability and image reproducibility of printing plates has been strongly desired. In order to improve the printing durability, a means of increasing the film thickness of the photosensitive layer or the anodized film is used, but this causes poor image reproducibility and limits the range of use.

It has been conventionally known that the provision of the anodizing layer improves the surface hardness of the aluminum plate and also improves the adhesiveness of the image part to the aluminum plate. It is already known that an aluminum plate anodized in phosphoric acid or an electrolyte solution containing phosphoric acid as a main component has better adhesiveness than an aluminum plate treated in an electrolyte solution such as sulfuric acid or oxalic acid. . Therefore, when a photo-dimerizable photopolymer or an azide-based photopolymer having a relatively low adhesive strength is used as the photosensitive layer, an anodized layer of phosphoric acid is often used (Japanese Patent Publication No. 46-26521, 54-37522, 57-22035
No. 57-22032 and U.S. Pat. No. 3,594,289).

[Problems to be solved by the invention]

However, in the case of the diazo type, since the adhesiveness is too strong, the use of an anodized layer of phosphoric acid tends to cause scumming, and it becomes impossible to erase, and it is said that there are many practical difficulties. ing.

Therefore, an object of the present invention is to provide a printing plate having improved image reproducibility, high film strength, and high printing durability.

Still another object of the present invention is to provide a printing plate having good erasability, causing no background stain, and having good storage stability.

[Means for Solving Problems] The present invention will be outlined. The present invention relates to a photosensitive lithographic printing plate, wherein the printing plate is phosphoric acid or an electrolyte solution containing phosphoric acid as a main component. A lipophilic polymer compound having a hydroxyl group and a diazo resin are contained on an aluminum plate having an anodized layer with an average pore diameter of 200 to 900Å and a pore density of 100 to 1000 / μm ² obtained by anodizing treatment. It is characterized in that a photosensitive layer is provided.

As a result of earnest studies by the present inventors, the above printing plate is
The inventors have found that the photosensitive lithographic printing plate has image reproducibility specifically improved, high printing durability, good storage stability and erasability, and does not cause scumming.

Hereinafter, the present invention will be specifically described.

The diazo resin used in the present invention can be prepared by a known method, for example, Photographic Science and Engineering (photo.Sci.Eng) Vol. 17, p. 33 (197).
3), by polycondensing a diazonium salt with an aldehyde such as paraformaldehyde, acetaldehyde or benzaldehyde in sulfuric acid, phosphoric acid or hydrochloric acid according to the method described in U.S. Pat. Can be obtained.

At that time, the diazonium salt and the aldehyde are usually used in a molar ratio.
A highly sensitive diazo resin can be obtained by charging at 1: 0.5 to 1: 2, preferably 1: 0.6 to 1: 1.5 and reacting at a low temperature for a short time, for example, at 10 ° C. or less for about 3 hours.

In the present invention, a PF ₆ salt or a BF ₄ salt of a diazo resin is preferable, and it is particularly represented by the following general formula I and n in the formula:
Is 5 mol or more, 20 mol% or more, preferably 20 to
A diazo resin containing 60 mol% is preferable.

(In the formula, R ¹ , R ² and R ³ represent a hydrogen atom, an alkyl group or an alkoxy group, R represents a hydrogen atom, an alkyl group or a phenyl group, X represents PF ₆ or BF ₄ , and n is 1 The diazo resin thus obtained is used, for example, as a mixture with a lipophilic polymer compound having a hydroxyl group. Examples of the lipophilic polymer compound having a hydroxyl group that can be used for this purpose include, for example, those derived from monomers such as acrylamides, methacrylamides, acrylic acid esters or methacrylic acid esters having a hydroxyl group as described below. And a copolymer having a molecular weight of 20,000 to 200,000, which contains the structural unit.

(1) A monomer having an aromatic hydroxyl group, for example, N-
(4-hydroxyphenyl) acrylamide or N-
(4-hydroxyphenyl) methacrylamide, o-, m
-, P-Hydroxystyrene, o-, m-, p-hydroxyphenyl-acrylate or methacrylate (2) Monomer having aliphatic hydroxyl group, for example, 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate Other monomer to be copolymerized (1) α, β-unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic anhydride, etc. (2) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, acrylic acid Hexyl, octyl acrylate, acrylic acid-
(Substituted) alkyl acrylate such as 2-chloroethyl, 2-hydroxyethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate (3) Methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, butyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, 2
-Hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, glycidyl methacrylate, N-
(Substituted) alkylmethacrylates such as dimethylaminoethylmethacrylate (4) Acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethyl Acrylamide such as acrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl-N-phenylacrylamide, or methacrylamide (5) Ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, Vinyl ethers such as butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether (6) Vinyl acetate , Vinyl chloroacetate, vinyl butyrate, vinyl benzoate, etc. (7) Styrenes such as styrene, α-methylstyrene, methylstyrene, chloromethylstyrene (8) Methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl Vinyl ketones such as ketones and phenyl vinyl ketones (9) Olefins such as ethylene, propylene, isobutylene, butadiene and isoprene (10) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile, etc. However, other monomers may be used as long as they are copolymerizable with a monomer having a hydroxyl group, and the present invention is not limited thereto. In addition to these, polyvinyl butyral resin, polyurethane resin, polyamide resin, epoxy resin, novolak resin, natural resin and the like may be added if necessary.

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

Various known additives shown below can be added to the photosensitive composition of the present invention in order to further improve the performance.

(1) Dyes for visualizing images (2) Fluorine-based surfactants and alkyl ethers for improving coating properties (3) To impart flexibility and abrasion resistance to coating films Plasticizer for (4) Oil sensitizer (5) Stabilizer The addition amount of these is generally 0.01 to 30% by weight based on the total solid content.
Is.

The photosensitive composition of the present invention is dissolved in a suitable solvent, for example, methyl cellosolve, methyl ethyl ketone, ethyl cellosolve, cyclohexanone, dioxane, ethyl acetate, benzyl alcohol, diacetone alcohol, etc., and coated on a support. The amount applied is usually about 0.5 to about 5 g / dry weight.
m ² . At this time, the aluminum plate used is anodized in phosphoric acid or an electrolytic solution containing phosphoric acid as a main component. For example, an aluminum plate in an aqueous solution containing 10 to 50% by weight, preferably 20 to 40% by weight of phosphoric acid, or 25% by weight or less, preferably 10% by weight in the phosphoric acid and the total acid.
Other acids below, for example, in an aqueous solution containing a mixed acid with sulfuric acid, oxalic acid, etc., at a bath temperature of 10 to 50 ° C, preferably 25 to 45 ° C,
Current density 0.2-10 A / dm ² , preferably 1-7 A / dm ² , 10
The average pore diameter of the obtained anodized layer is 200 to 900Å, preferably 30 to 10 minutes, preferably 20 seconds to 3 minutes.
0 to 900Å, particularly preferably 400 to 900Å, with a pore density of 10
The anodized product is used so that the anodization amount is 0 to 1,000 pieces / μm ² , preferably 100 to 500 pieces / μm ² , and particularly preferably 100 to 350 pieces / μm ² .

In the present invention, before and after the anodizing treatment, it is preferable to carry out surface treatment such as brush polishing, graining treatment such as electrolytic etching, and / or hydrophilic treatment according to known methods.

Examples of the hydrophilic treatment include hot water sealing and sodium silicate treatment, but sodium silicate treatment is preferable from the viewpoints of adhesiveness, diazo residue and developability. The conditions for the sodium silicate treatment are as follows.
It is performed by immersing at 0 ° C to 95 ° C for 10 seconds to 5 minutes. Preferably, after that, it is immersed in water at 60 ° C to 100 ° C for 10 seconds to 5 minutes for treatment.

On the photosensitive lithographic printing plate thus produced, an object is overlaid and exposed by an ordinary method, or an image is written by irradiating with an electron beam or the like to write an image, and then developed with a developer to obtain a support. A corresponding image can be formed on top. Suitable light sources for exposure include metal halide lamps, mercury lamps, carbon arc lamps and the like.

The developing solution used for the development treatment of the photosensitive printing plate according to the present invention may be any known one, but preferably the following. That is, the developer for developing the photosensitive printing plate according to the present invention includes water or an aqueous solution containing a specific organic solvent and / or an alkaline agent. Here, the specific organic solvent is capable of dissolving or swelling the non-exposed area (non-image area) of the above-mentioned photosensitive composition layer when contained in a developing solution, and is water at room temperature (20 ° C). Refers to an organic solvent having a solubility of 10% by weight or less. Such an organic solvent only needs to have the above-mentioned characteristics, and is not limited to the following, but if these are exemplified, for example, ethyl acetate, propyl acetate, acetic acid, etc. Butyl, amyl acetate, benzyl acetate,
Carboxylic acid esters such as ethylene glycol monobutyl acetate, butyl lactate and butyl levulinate; ketones such as ethyl butyl ketone, methyl isobutyl ketone and cyclohexanone; ethylene glycol monobutyl ether, ethylene glycol benzyl ether,
Alcohols such as ethylene glycol monophenyl ether, benzyl alcohol, methylphenyl carbinol, n-amyl alcohol, methyl amyl alcohol; alkyl-substituted aromatic hydrocarbons such as xylene; methylene dichloride, ethylene dichloride, monochlorobenzene, etc. There are various halogenated hydrocarbons. One or more of these organic solvents may be used. Among these organic solvents, ethylene glycol monophenyl ether and benzyl alcohol are particularly effective. Further, the content of these organic solvents in the developing solution is approximately 1 to 20% by weight, and particularly preferable results are obtained when the content is 2 to 10% by weight.

On the other hand, as the alkaline agent contained in the developer, (A) sodium silicate, potassium silicate, potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium or ammonium salt of secondary or tertiary phosphate, Inorganic alkaline agents such as sodium metasilicate, sodium carbonate, ammonia (B) mono-, di- or trimethylamine, mono-, di- or triethylamine, mono- or diisopropylamine, n-
Examples include organic amine compounds such as butylamine, mono-, di- or triethanolamine, mono-, di- or triisopropanolamine, ethyleneimine and ethylenediamine.

The content of these alkaline agents in the developer is usually 0.05.
-4% by weight, preferably 0.5-2% by weight.

Further, in order to further improve storage stability, printing durability and the like, it is preferable to include a water-soluble sulfite in the developer. As such a water-soluble sulfite, an alkali or alkaline earth metal salt of sulfite is preferable, and examples thereof include sodium sulfite, potassium sulfite, lithium sulfite and magnesium sulfite. The content of these sulfites in the developer composition is usually 0.05 to 4% by weight, preferably 0.1 to 1% by weight.

Further, a certain solubilizing agent may be contained in order to assist the dissolution of the above organic solvent in water. As such a solubilizing agent, in order to realize the intended effect of the present invention, it is preferable to use a low molecular weight alcohol or ketone which is more soluble in water than the organic solvent used. Moreover, an anion activator, an amphoteric activator, etc. can also be used. Examples of such alcohols and ketones include methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methoxybutanol, ethoxybutanol, 4-methoxy-4-methylbutanol, N. -It is preferable to use methylpyrrolidone or the like. Further, as the activator, for example, sodium isopropylnaphthalene sulfonate, sodium n-butylnaphthalene sulfonate, sodium N-methyl-N-pentadecylaminoacetate, sodium lauryl sulfate, and the like are preferable. The amount of the solubilizer such as alcohol or ketone used is not particularly limited, but is generally preferably about 30% by weight or less based on the entire developer.

The photosensitive printing plate according to the present invention is, after imagewise exposure, brought into contact with the above-mentioned developing solution or rubbed, after about 10 to 60 seconds at room temperature to 40 ° C., a photosensitive composition. The unexposed areas of the photosensitive composition will be completely removed without adversely affecting the exposed areas of the layer.

The production examples of the grain, diazo resin and polymer used in the present invention are shown below.

[Grain-1] An aluminum plate in a 17g / l hydrochloric acid bath at a bath temperature of 25 ° C and 50A
Electropolishing treatment was performed for 25 seconds at / dm ² to obtain a grained plate having a maximum roughness of 4 μm. The grained board was anodized in a 40% by weight phosphoric acid bath at a bath temperature of 40 ° C. at 4 A / dm ² for 30 seconds, thoroughly washed with water and air dried. When the obtained anodized layer was analyzed by an electron microscope, 175 pores with an average pore diameter of 750Å / μ
m ² confirmed.

[Grain-2] An aluminum plate grained in the same manner as in [Grain-1] was placed in a mixed acid bath of 30 wt% phosphoric acid and 2.5 wt% sulfuric acid at a bath temperature of 40 ° C for 4A. The sample was anodized at / dm ² for 30 seconds, washed thoroughly with water, and air dried. When the obtained anodized layer was analyzed by an electron microscope, 220 pores / μm ² having an average pore diameter of 500Å were confirmed.

[Grain-3] Similarly to [Grain-2], the anodized layer obtained under the same conditions in a mixed acid bath of 30 wt% phosphoric acid and 5 wt% sulfuric acid was It was confirmed that 350 pores with an average pore diameter of 350Å were formed / μm ² .

[Grain-4] In the same manner as in [Grain-2], the anodized layer obtained under the same conditions in a mixed acid bath of 30 wt% phosphoric acid and 30 wt% sulfuric acid was 1000 pores with an average pore diameter of 250Å / μm ²
It was confirmed that it was formed.

[Grain-5] An aluminum plate that has been grained in the same manner as [Grain-1] in a 30 wt% sulfuric acid bath at a bath temperature of 30 ° C is 6 A / dm ²
Was anodized for 30 seconds, washed thoroughly with water, and then air dried.
The resulting anodized layer was analyzed in the same manner as in Reference Example 1, pores having an average pore diameter of 130Å was confirmed 1,000 / [mu] m ² or more.

[Grain-6] Anodized layer obtained in the same manner as in [Grain-5] with a current density of 4 A / dm ² under the same conditions as above has an average pore diameter of 80Å.
It was confirmed that 1000 pores / μm ² or more were formed.

[Grain-7] Anodized layer obtained under the same conditions as in [Grain-1] except that the current density was 9 A / dm ² and the average pore diameter was 950Å
100 pores / μm ^{2 were} confirmed.

[Synthesis of Polymer 1] N- (4-hydroxyphenyl) methacrylamide 10.0
g, acrylonitrile 25 g, ethyl acrylate 60 g, methacrylic acid 5 g and azobisisobutyronitrile 1.642 g were dissolved in acetone-methanol 1: 1 mixed solvent 112 ml, and after nitrogen substitution, the mixture was heated at 60 ° C. for 8 hours.

After completion of the reaction, the reaction solution was poured into 5 liters of water with stirring and the white precipitate formed was dried to obtain 90 g of Polymer 1.

When the molecular weight of this polymer was measured by gel permeation chromatography (hereinafter abbreviated as GPC), the weight average molecular weight was 85,000.

[Synthesis of Polymer 2] 2-Hydroxyethyl Methacrylate 45 g, Acrylonitrile 10 g, Ethyl Methacrylate 45 g, Methacrylic Acid 2 g
And 1.2 g of benzoyl peroxide were added dropwise to 300 g of ethylene glycol monomethyl ether heated to 100 ° C. over 2 hours. After completion of the dropping, 300 g of ethylene glycol monomethyl ether and 0.3 g of benzoyl peroxide were added and the reaction was continued for 4 hours. After completion of the reaction, the mixture was diluted with methanol and poured into 5 liters of water with stirring, and the resulting white precipitate was dried to obtain 93 g of Polymer 2.

When the molecular weight of this polymer was measured by GPC,
The weight average molecular weight was 65,000.

[Synthesis of Polymer 3] 60 g of methyl methacrylate, 30 g of acrylonitrile, 10 g of methacrylic acid and 1.5 g of azobisisobutyronitrile were dissolved in 200 g of methyl cellosolve and polymerized at 80 ° C. for 4 hours while passing nitrogen through. The reaction mixture was added dropwise to 5 l of water, and the white precipitate formed was dried to give 70 g of Polymer 3.
Obtained.

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

[Synthesis of Polymer 4] 70 g of ethyl methacrylate, 20 g of acrylonitrile, and 10 g of methacrylic acid were polymerized in the same manner as in Synthesis Example of Polymer 3 to obtain Polymer 4.

When the molecular weight of this polymer was measured by GPC, the weight average molecular weight was 63,000.

[Synthesis of diazo resin-1] 14.5 g (50 mmol) of p-diazodiphenylamine sulfate was dissolved in 40.9 g of concentrated sulfuric acid under ice cooling. 1.2 g (40 mmol) of paraformaldehyde was slowly added dropwise to this reaction solution. At this time, the reaction temperature was added so that the temperature did not exceed 10 ° C. After that, stirring was continued for 2 hours under ice cooling.

The reaction mixture was added dropwise to 500 ml of ethanol under ice cooling, and the formed precipitate was passed through. After washing with ethanol, the precipitate was dissolved in 100 ml of pure water, and to this solution was added a cold concentrated aqueous solution containing 6.8 g of zinc chloride. After passing through the generated precipitate, it was washed with ethanol and dissolved in 150 ml of pure water. To this solution was added a cold concentrated aqueous solution in which 8 g of ammonium hexafluorophosphate was dissolved. The resulting precipitate was collected, washed with water, and dried at 30 ° C for one day to obtain diazo resin-1.

When the molecular weight of this diazo resin-1 was measured by GPC, it contained about 35 mol% of a pentamer or more.

[Synthesis of diazo resin-2] Synthesized in the same manner as diazo resin-1, and treated with an aqueous solution in which 15 g of 2-hydroxy-4-methoxy-benzophenone-5-sulfonic acid was dissolved in place of the final ammonium hexafluorophosphate. Diazo resin-2 was obtained.

When this diazo resin-2 was measured by GPC, it contained about 32 mol% of a pentamer or more.

〔Example〕

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

Examples 1 to 4 and Comparative Examples 1 to 3 Photosensitive liquid-1 having the following composition was applied to the sands 1 to 7 obtained in the above-mentioned production example using a whirler. Then, it was dried at a temperature of 85 ° C. for 3 minutes to obtain a photosensitive lithographic printing plate. The coating amount was 2.0 g / m ^{2 as a} dry weight.

(Photosensitive liquid-1) The photosensitive lithographic printing plate obtained was 60 cm with a 3 KW ultra-high pressure mercury lamp.
Was exposed for 30 seconds from the above distance and developed with Developer-1 to obtain a lithographic printing plate.

(Developer-1) The sensitivity, dot thickness, printing durability, erasability and storage stability of the obtained lithographic printing plate were measured. The results are shown in Table 1.

The printing durability was defined as the number of sheets printed on a high-quality paper with a sheet-fed offset printing machine, and the number of sheets in which flat screen scraping or defective inking occurred.

It can be seen from Table 1 that the printing plate of the present invention has a high printing durability, a small dot weight is smaller than that of alumite sulfate, and a good dot reproducibility. Further, when the erasability of unnecessary images was compared using the erasing liquid N-300 containing 1.5% by weight of hydrogen fluoride, only 950Å grain-7 was not completely erased. Further, when the storage stability (40 ° C., RH 80%) was compared between grain-1 and grain-7, only the grain-7 was stained.

Examples 5 to 7 and Comparative Examples 4 to 5 The following photosensitive solution-2 was applied to the grain-2. Expose this,
After development, the sensitivity, the amount of dot thickening, the printing durability, and the storage stability were measured. The results are shown in Table 2. The coating amount was 1.5 g / m ^{2 as a} dry weight.

(Photosensitive liquid-2) From Table 2, a printing plate obtained by applying a photosensitive solution containing a polymer having a hydroxyl group to an aluminum plate-2 anodized with an electrolyte solution containing phosphoric acid as a main component has excellent storage stability and high printing durability. I understand.

Example 8 and Comparative Examples 6 and 7 The following Photosensitive Solution-3 was applied to the sand grains-1, -5 and -6.
This was exposed and developed to measure the sensitivity and the film strength. The results are shown in Table 3. The coating amount was 1.5 g / m ^{2 as a} dry weight.

(Photosensitive liquid-3) From Table 3, it can be seen that the printing plate of the present invention has extremely excellent film strength.

Example 9 and Comparative Examples 8 to 11 The following Photosensitive Solution 4 was applied to the grains 1, 5, and 7. This was exposed and developed in the same manner as in Example 1 to measure the sensitivity, halftone dot reproducibility, printing durability, erasability and storage stability. The results are shown in Table 4. The coating amount was 1.5 g / m ^{2 as a} dry weight.

(Photosensitive liquid-4) From Table 4, by combining a lipophilic polymer compound having a hydroxyl group with a phosphoric acid anodic oxide layer having an average pore diameter of 200 to 900Å and a pore density of 100 to 1000 / μm ² , it is possible to obtain specific storage stability. It can be seen that the printing durability is excellent while maintaining the erasability and erasability.

〔The invention's effect〕

As described in detail above, the photosensitive lithographic printing plate of the present invention is excellent in image reproducibility, high printing durability, good storage stability and erasability, and does not cause scumming. It has a great effect.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Shinya Sanryo Kasei Kogyo Co., Ltd. Research Institute (Shinryo Kasei Kogyo Co., Ltd.) (No. 59) ) JP 56-121031 (JP, A) JP 55-17580 (JP, A) JP 58-153698 (JP, A)

Claims (5)

[Claims] 1. An anodic oxide layer having an average pore diameter of 200 to 900Å and a pore density of 100 to 1000 pores / μm ² obtained by anodizing in phosphoric acid or an electrolyte solution containing phosphoric acid as a main component. A photosensitive lithographic printing plate comprising an aluminum plate and a photosensitive layer containing a lipophilic polymer compound having a hydroxyl group and a diazo resin provided on the aluminum plate. 2. A polymer containing a structural unit derived from a monomer selected from the group consisting of acrylamides, methacrylamides, acrylic esters and methacrylic esters having a hydroxyl group. The photosensitive lithographic printing plate according to claim 1, which is a compound. 3. The diazo resin according to claim 1, which is a condensate of a substituted or unsubstituted p-diazodiphenylamine and an aldehyde, and whose anion is PF ₆ or BF ₄ . Photosensitive lithographic printing plate. 4. The diazo resin has the following general formula I: (In the formula, R ¹ , R ² and R ³ represent a hydrogen atom, an alkyl group or an alkoxy group, R represents a hydrogen atom, an alkyl group or a phenyl group, X represents PF ₆ or BF ₄ , and n is 1 The number of the resin is represented by the formula (1) to (200) and n in the formula contains 5 or more resins in an amount of 20 mol% or more.
The photosensitive lithographic printing plate described in the item. 5. The photosensitive lithographic printing plate according to claim 1, wherein the anodic oxide layer has an average pore diameter of 300 to 900Å and a pore density of 100 to 500 pores / μm ² .