JPH09226266A - Manufacture of lithographic printing plate support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to conduct uniform graining and to improve scumming difficulty and plate wear resistance by roughing it by an alternating current, cathode electrolytically decomposing an aluminum web and further roughing with the alternating current in a method for electrochemically roughing the aluminum web in an acid electrolyte containing a metal ion. SOLUTION: This lithographic printing plate support using aluminum or an aluminum alloy has suitable adhesive properties with a photosensitive material and water retaining properties, and is uniformly roughed. When the roughing is conducted by using electrochemical roughing in acid electrolyte containing a metal ion, the support is roughed with alternating current, an aluminum web is cathode electrolytically decomposed, and further roughed with the alternating current. The electrolyte contains Al ion and Fe (II) ion, and the Al ion is preferable to generate smut. The metal ion in the electrolyte is preferably 0.1 to 50g/l, and the electric amount of the cathode electrolysis is preferably 0.5 to 100c/dm<2> .

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a support for a lithographic printing plate, particularly aluminum,
The present invention relates to a manufacturing method using an aluminum alloy.

[0002]

2. Description of the Related Art Aluminum and aluminum alloys have been used as aluminum supports for printing plates, especially lithographic printing plates. Generally, in order to use an aluminum plate as a lithographic printing plate substrate, it is necessary that the aluminum plate has appropriate adhesion to a photosensitive material and water retention, and that the surface is evenly roughened. To be uniformly roughened means that the size of the pits that have been formed is reasonably uniform and that such pits are formed uniformly over the entire surface. In addition, the pits have a remarkable effect on the printing performance of the printing plate, such as stain resistance, printing durability, and the like, and its quality is an important factor in the printing plate production. Mechanical surface roughening, chemical surface roughening, electrochemical surface roughening, etc. can be used as the surface roughening method of the substrate, but the alternating current electrolytic etching method is generally adopted as the electrochemical surface roughening method. As the current waveform, an ordinary sinusoidal alternating current, a special alternating waveform current such as a rectangular wave is used. Then, an appropriate electrode such as graphite is used as a counter electrode, and roughening treatment is performed by an alternating current. The electrochemical roughening treatment is usually performed once, but the same treatment is repeated twice as necessary, or the roughening treatments are overlapped under different conditions. It is being appreciated. In addition, Japanese Examined Japanese Patent Publication No. 57-4963
Japanese Patent Publication No. 8 proposes that uniform graining can be achieved by flowing an alternating waveform current. JP-A-3-797
In Japanese Patent Laid-Open No. 99, the present inventors propose to perform uniform graining from a power supply waveform.

[0003]

However, as the quality demands from users are increasing today, higher quality substrates, especially stain resistance under severe conditions and higher printing durability are required. Therefore, the required performance could not be satisfied by the above method. The purpose of the present invention is
It is an object of the present invention to provide a lithographic printing plate support that solves the above problems, enables uniform graining, and is excellent in stain resistance and printing durability.

[0004]

As a result of intensive studies, the present inventors have found the following invention. That is, the above-mentioned object is, in an acidic electrolytic solution containing metal ions, in a method of electrochemically roughening an aluminum web, roughening with an alternating current, cathodic electrolysis of the web, and further alternating current. It is achieved by a method for producing a lithographic printing plate support, which is characterized by roughening the surface.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. The aluminum plate used in the present invention includes pure aluminum and aluminum alloy. Various materials can be used as the aluminum alloy, for example, silicon, copper, manganese, magnesium, chromium, zinc, lead, nickel,
Alloys such as bismuth and aluminum alloys are used.
There are various aluminum alloys, but as a plate material for offset printing, for example, in JP-B-58-6635, there is F
The e and Si components are limited, and the intermetallic compound is specified.
Further, in Japanese Examined Patent Publication No. 55-28874, the cold rolling rate and intermediate blunting are performed to limit the voltage application method for electrolytic surface roughening. Japanese Patent Publication 62-41304, Japanese Patent Publication 1-465
77, Japanese Patent Fair 1-46578, Japanese Patent Fair 1-47545,
Japanese Patent Publication 1-35910, Japanese Patent Publication No. 63-60823, Japanese Patent Publication No. 63-60824, Japanese Patent Publication No. 4-41717, Japanese Patent Publication No. 4
-19290, Japanese Patent Publication No. 4-19291, Japanese Patent Publication No. 4-19
293, JP-B-62-50540, and JP-A-61-272.
357, JP-A-62-74060, JP-A-61-201
747, JP-A-63-143234, JP-A-63-14
3235, JP-A-63-255338, JP-A-1-28
3350 gazettes, EP272528, US Patent 490
2353, 4818300, EP394816, US Pat. No. 5,019,188, West German Patent 3232810, US Pat. No. 435230, EP239995, US Pat.
22715, West German Patent 3507402, US Patent 4
715903, West German Patent 3507402, EP28.
9844, US Pat.
4, West German Patent 3714059, US Patent 46860
In addition to the aluminum alloys shown in the respective specifications of No. 83, No. 4861396 and EP1588941, all general alloys are included. As a method of manufacturing a plate material, a method using hot rolling and a method of performing continuous casting have been recently applied. For example, East German Patent 252799
In the specification, a plate material manufactured by a twin roll method is introduced. EP 223737, US Pat.
No. 5,480,950, each specification is applied in a form in which trace alloy components are limited. EP 415238 proposes continuous casting, continuous casting + hot rolling. In the present invention, such an aluminum plate can be subjected to various surface treatments, transfer and the like to obtain a printing base plate having uniform unevenness, and by providing a photosensitive layer such as a diazo compound on the printing base plate, excellent photosensitivity can be obtained. A lithographic printing plate can be obtained. In any case, it is necessary to select an appropriate material.

Next, the processing conditions for these aluminum plates will be shown. The present invention relates to electrolytic surface roughening, but mechanical surface roughening, chemical surface roughening and the like may be combined. Japanese Patent Publication No. 57-16918 discloses a combination invention. First, a process performed as necessary before mechanical graining will be described. A method using a solvent such as trichlene or a surfactant or a method using an alkali etching agent such as sodium hydroxide or potassium hydroxide is widely used. Japanese Patent Application Laid-Open No. 2-026793 describes a degreasing treatment. For example, as a solvent degreasing method, a method using a petroleum solvent such as gasoline, kerosene, benzine, solvent naphtha, and normal hexane,
There is a method of using a chlorine-based solvent such as tolchlorethylene, methylene chloride, perchlorethylene, and 1,1,1-trichloroethane. As an alkaline degreasing method, sodium hydroxide, sodium carbonate, sodium bicarbonate,
Method using an aqueous solution of soda salt such as sodium sulfate, method using an aqueous solution of silicate such as sodium orthosilicate, sodium metasilicate, sodium No. 2 silicate, sodium No. 3 silicate, sodium monophosphate, triphosphoric acid There is a method of using an aqueous phosphate solution of sodium, dibasic sodium phosphate, sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate and the like. When using the alkaline degreasing method, depending on the treatment time and treatment temperature,
Since it is possible that the aluminum surface may dissolve, the degreasing process should be free from dissolution phenomena. As the degreasing treatment with a surfactant, an aqueous solution of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant is used, and various commercial products can be used. As the degreasing method, the dipping method,
A spraying method, a method in which a liquid is immersed in a cloth or the like, and rubbed can be used. Ultrasonic waves may be used for the dipping method and the spraying method. There are various methods such as transfer, brush, and liquid honing for mechanical surface roughening, and it is necessary to select them in consideration of productivity and the like.

Various methods can be used as a transfer method in which the uneven surface is pressed against the aluminum plate. That is, the above-mentioned JP-A-55-74898 and JP-A-60-3
No. 6195, Japanese Patent Laid-Open No. 60-203496,
Japanese Patent Laid-Open No. 6-55871, which is characterized in that transfer is performed several times.
Japanese Unexamined Patent Publication No. 6-
The method disclosed in Japanese Patent No. 24168 is also applicable. Also, by using electrical discharge machining, shot blasting, laser, plasma etching, etc., it is possible to perform repeated transfer using a roll that has fine irregularities etched, and to contact the aluminum plate with the irregular surface coated with fine particles. The surface may be faced, and pressure may be repeatedly applied thereto a plurality of times to repeatedly transfer the concavo-convex pattern corresponding to the average diameter of the fine particles a plurality of times onto the aluminum plate. As a method for imparting fine unevenness to the transfer roll, there are disclosed in JP-A-3-08635 and JP-A-3.
No. 066404 and Japanese Patent Laid-Open No. 63-065017 are known. Also, dies on the roll surface,
Fine grooves may be cut from two directions by using a cutting tool or a laser to form square irregularities on the surface. The surface of this roll may be subjected to a known etching treatment or the like so that the formed square irregularities are rounded. Needless to say, quenching, hard chrome plating, etc. may be performed to increase the hardness of the surface.

The roughening with a brush includes not only roughening with a nylon brush but also roughening with a wire brush. Further, as surface roughening with high-pressure water, there are JP-A-59-21469 and JP-A-60-19595.
Japanese Patent Laid-Open No. 60-18390 and the like.

After performing such mechanical surface roughening, if necessary, the aluminum surface is chemically treated with an acid or alkali for the purpose of smoothing and uniformizing the aluminum plate.
Particularly, in the case of performing electrochemical surface roughening, the surface roughening becomes non-uniform when the surface is continuously transferred after the transfer. Specific examples of the acid and alkali used in such chemical treatment include a method using an aqueous solution of soda salt such as phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium sulfate, orthosilicate. Method using an aqueous solution of silicate such as sodium phosphate, sodium metasilicate, sodium silicate No. 2, sodium silicate No. 3, sodium monophosphate, sodium phosphate tribasic, sodium phosphate dibasic, sodium tripolyphosphate, pyrophosphate There is a method of using an aqueous solution of a phosphate such as sodium or sodium hexametaphosphate. The processing conditions include a concentration of 0.01% to 50% by weight, a temperature of 20 ° C to 90 ° C, and a time of 5%.
The time is selected from seconds to 5 minutes. The etching amount is appropriately selected depending on the material of aluminum and the required quality. JP-A-54-65607, JP-A-55-125
In the 299 publications, a pretreatment for electrochemical graining is proposed. JP-A-63-235500, JP-A-63-3
07990, JP-A-1-127388, JP-A-1-16
0690, JP-A-1-136789, JP-A-1-136.
788, JP-A-1-178497, JP-A-1-3086
89, JP-A-3-126871, JP-A-3-12690.
No. 0, JP-A-3-173800 and the like include various pretreatments, but the present invention is not limited to these. However, when the aluminum surface is chemically treated with an acid / alkali aqueous solution in this manner, an insoluble residue portion, that is, smut, is generated on the surface. This smut can be removed with phosphoric acid, nitric acid, sulfuric acid, chromic acid or mixtures thereof. In the present invention,
The aluminum surface to be subjected to the electrochemical graining treatment is preferably a clean surface without smut. However, when the electrolytic solution is an acid and has a desmutting effect, this can be omitted.

The invention is characterized in that, in the method for electrochemically roughening an aluminum plate treated in this way, cathodic electrolysis is incorporated during the roughening.
Therefore, the electrochemical graining is performed at least twice. In addition, the cathodic electrolysis is performed at least once, and by incorporating the cathodic electrolysis, smut is created on the Al surface and hydrogen gas is generated, so that more uniform electrolytic surface roughening is possible.

Regarding electrochemical graining, Japanese Patent Publication No. 48
-28123 and British Patent 896563. Conventionally, the electrolytic graining uses an alternating current having a sinusoidal waveform.
Alternatively, a special waveform as described in Japanese Patent No. 602 may be used. Further, JP-A-55-158298, JP-A-56-28898, JP-A-52-58602, JP-A-52-152302, JP-A-54-85802, JP-A-60-190392, and JP-A-58-120531. JP-A-63-176187, JP-A-1-588.
9, JP-A-1-280590, JP-A-1-11848
9, JP-A-1-148592, JP-A-1-17849
6, JP-A-1-188315, JP-A-1-15479
7, JP-A-2-235794, JP-A-3-26010
0, JP-A-3-253600, JP-A-4-72079,
The methods described in JP-A-4-72098, JP-A-3-267400, and JP-A-1-141094 can also be applied. As the frequency, in addition to the above, those proposed for electrolytic capacitors can also be used. For example, U.S. Pat. Nos. 4,276,129 and 4,676,879.

As the acidic electrolyte, nitric acid, hydrochloric acid, etc., as well as the above-mentioned ones, US Pat.
61219, 4618405, 462628, 4
600482, 4566960, 4566958,
Same 4566959, same 4416972, same 437471
No. 0, No. 4,336,113, No. 4,184,932, and other electrolytic solutions can also be used. Various proposals have been made for electrolytic cells and power sources, but U.S. Pat. No. 4,203,637, JP-A-56-123400, JP-A-57-59770, JP-A-53-12738, JP-A-53-32821, JP-A-53-32822, JP-A-53-32823, JP-A-55-122896, JP-A-55-132884, JP-A-62-127500, and Japanese Patent Application No. 62-2065.
831, Japanese Patent Application No. 62-2065841, Japanese Patent Application No. 58-1
73674, Japanese Patent Application No. 63-54783, Japanese Patent Application No. 2-53
758, etc. In addition to the patents mentioned above, various proposals have been made. For example, JP-A-52-586
02, JP-A-52-152302, JP-A-53-127.
38, JP-A-53-12739, JP-A-53-3282
1, JP-A-53-32822, JP-A-53-3283
3, JP-A-53-32824, JP-A-53-3282
5, JP-A-54-85802, JP-A-55-12289
6, JP-A-55-132884, JP-B-48-2812
3, JP-B-51-7081, JP-A-52-13383
8, JP-A-52-133840, JP-A-52-1338
44, JP-A-52-133845, JP-A-53-149.
135, and those described in JP-A-54-146234 can also be applied.

The metal ions contained in the acidic electrolyte are, for example, Al ions, Fe (II) ions and M ions.
Examples thereof include n (II) ions and Mg ions, and Al ions are preferable for producing smut. The metal ion in the electrolytic solution is preferably 0.1 to 50 g / l, more preferably 0.3 to 5 g / l. The quantity of electricity for cathodic electrolysis is 0.5
preferably ^{c / dm 2 ~100c / dm 2} , more preferably 2 to 3
It is 0 c / dm ² .

If necessary, the aluminum plate thus obtained is treated with an alkali or an acid. Alkali treatment as in JP-A-56-51388 and desmutting treatment with sulfuric acid as in JP-A-53-12739. Further, phosphoric acid treatment as described in JP-A-53-115302, JP-A-60-8091,
JP-A-63-176188, JP-A-1-38291, JP-A-1-127389, Japanese Patent Application No. 1-188699, JP-A-3-177600, JP-A-3-126891, JP-A-3-191100 and the like are also used. Can be done.

It is preferable to form an anodic oxide film on the surface of the aluminum support thus obtained. As the electrolytic solution, sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, or the like, or an aqueous solution or a non-aqueous solution in which two or more kinds of these are combined is used.
An anodized film can be formed. The treatment conditions for anodizing vary variously depending on the electrolytic solution used, so it cannot be said unequivocally, but generally the concentration of the electrolytic solution is 1
~ 80% by weight, liquid temperature 5-70 ° C, current density 0.5-60
A / cm ² , a voltage of 1 to 100 V, and an electrolysis time of 15 seconds to 50 minutes are suitable. As an electrolysis device, Japanese Patent Laid-Open No. 48-2663
8, JP-A-47-18739, JP-B-58-24517
It is introduced in each issue. Also, JP-A-54-81
133, JP-A-57-47894, and JP-A-57-512.
89, JP-A-57-51290, JP-A-57-5430.
0, JP-A-57-136596, JP-A-58-1074
98, JP-A-60-200256, JP-A-62-136.
596, JP-A-60-176494, and JP-A-4-176.
897, JP-A-4-280997, and JP-A-6-2072.
99, JP-A-5-24377, JP-A-5-32083,
Of course, the methods described in JP-A-5-125597 and JP-A-5-195291 can also be used. As the treatment liquid, JP-A-3-253596 and JP-A-62-8208 are available.
9, JP-A-1-133794, JP-A-54-3242
4. Of course, the liquids described in JP-A-5-42783 and the like can also be used.

After forming the anodic oxide film as described above,
In order to optimize the adhesion between each support and the photosensitive composition, after etching the anodic oxide film, water vapor and
There is an apparatus for sealing a support, which provides a photosensitive printing plate which is subjected to sealing treatment with hot water and has good stability over time, good developability, and no stains on non-image areas. (Postal No. 12518) A film formation post-treatment may be carried out with such an apparatus. Further, JP-A-4-4194 and JP-A-5-2024
No. 96, Japanese Patent Laid-Open No. 179482/1993 may be used for the sealing treatment.

In addition, the treatment with potassium fluorozirconate described in US Pat. No. 2,946,638, the treatment with phosphomolybdate described in US Pat. No. 3,201,247, and British Patent No. 1108559. Alkyl titanate treatment, German Patent No. 10
No. 91433 specification, polyacrylic acid treatment, German Patent No. 1134093 and British Patent No. 1
Polyvinylphosphonic acid treatment described in JP-A-230447, phosphonic acid treatment described in JP-B-44-6409, JP-A-58-16893 and JP-A-58-18291. Treatment with a salt of a lipophilic organic polymer compound and a divalent metal, and as described in US Pat. No. 3,860,426, hydrophilicity containing a water-soluble metal salt (eg, zinc acetate). Cellulose (eg carboxymethyl cellulose)
Undercoating or a hydrophilic treatment by undercoating of a water-soluble polymer having a sulfonic acid group described in JP-A-59-101651,
JP-A-2-019494, water-soluble epoxy compounds described in JP-A-62-033692, phosphoric acid-modified starch described in JP-A-62-097892, Diamine compounds described in JP-A-63-056498, JP-A-63-13039
Inorganic or organic acids of amino acids described in JP-A No.
Organic phosphonic acids containing a carboxyl group or a hydroxyl group described in JP-A-3-145092, US Pat.
Phytic acid treatment described in Japanese Patent No.
Compounds having an amino group and a phosphonic acid group described in JP-A-3-165183, a specific carboxylic acid derivative described in JP-A-2-316290, and JP-A-3-215095.
The phosphoric acid ester described in JP-A-3-26159
No. 2, a compound having one amino group and one phosphorus oxygen acid group, a phosphoric acid ester described in JP-A-3-215095, and a phenylphosphonic acid described in JP-A-5-246171. Such as aliphatic or aromatic phosphonic acids, compounds containing S atom such as thiosalicylic acid described in JP-A-1-307745, JP-A-4-282
It is also possible to carry out undercoating of a compound having a group of phosphorus oxygen acid as described in JP-A-637-63, or coloring with an acid dye described in JP-A-60-64352.

The support of the present invention may be provided with a photosensitive layer exemplified below to form a photosensitive lithographic printing plate. [I] In the case of providing a photosensitive layer containing an o-naphthoquinonediazide sulfonate and a phenol / cresol mixed novolak resin. The o-quinonediazide compound is an o-naphthoquinonediazide compound, for example, U.S. Patent Nos. 2,766,118 and 2,767,09.
No. 2, No. 2,772,972, No. 2,859,1
No. 12, No. 3,102,809, No. 3,106,
Nos. 465, 3,635,709 and 3,64
No. 7,443, each of which is described in many publications, and these can be suitably used. Among these, o-naphthoquinone diazide sulfonic acid ester or o-naphthoquinone diazide carboxylic acid ester of aromatic hydroxy compound, and o-naphthoquinone diazide sulfonic acid amide or o-naphthoquinone diazide carboxylic acid amide of aromatic amino compound are particularly preferable. , Especially o-naphthoquinonediazide sulfonic acid ester reaction of the condensate of pyrogallol and acetone described in U.S. Pat. No. 3,635,709, U.S. Pat. No. 4,028,111. A polyester having a hydroxy group at the terminal as described, which is obtained by esterifying o-naphthoquinonediazide sulfonic acid or o-naphthoquinonediazide carboxylic acid, as described in British Patent No. 1,494,043. P-hydroxy Hylene homopolymers or copolymers thereof with other copolymerizable monomers are esterified with o-naphthoquinone diazide sulfonic acid or o-naphthoquinone diazide carboxylic acid, US Pat. No. 3,759,711. P- as described in the specification
O-naphthoquinone diazide sulfonic acid, or o-
The amide reaction of naphthoquinone diazide carboxylic acid is very excellent.

These o-quinonediazide compounds can be used alone, but are preferably used in combination with an alkali-soluble resin. Suitable alkali-soluble resins include novolak-type phenol resins, and specifically include phenol formaldehyde resin, o-cresol formaldehyde resin, m-cresol formaldehyde resin, and the like. Further, U.S. Pat. No. 4,028,
As described in Japanese Patent No. 111, a condensate of formaldehyde and phenol or cresol substituted with an alkyl group having 3 to 8 carbon atoms such as t-butylphenolformaldehyde resin is used together with the above-mentioned phenol resin. Then, it is even more preferable. Further, in order to form a visible image by exposure, such as o-naphthoquinonediazide-4-sulfonyl chloride, inorganic anion salt of p-diazodiphenylamine, trihalomethyloxadiazole compound, trihalomethyloxadiazole compound having a benzofuran ring, etc. A compound or the like is added. On the other hand, as a colorant for the image, a triphenylmethane dye such as Victoria Blue BOH, crystal violet or oil blue is used. Also, JP-A-62-2932
The dye described in JP-B-47 is particularly preferred. Further, as an oil sensitizer, a phenol substituted with an alkyl group having a carbon number of 3 to 15 as described in JP-B-57-23253, such as t-butylphenol, N-.
Octylphenol, a novolak resin obtained by condensing t-butylphenol and formaldehyde, or o-naphthoquinonediazide-4 of such a novolak resin.
-Or-5-sulfonic acid ester (see, for example, Japanese Patent Laid-Open No.
No. 242446). Further, in order to improve the developability, a nonionic surfactant as described in JP-A-62-251740 can be further contained. The above composition is dissolved in a solvent that dissolves the above components and applied on a support. As the solvent used here, ethylene dichloride, cyclohexanone, methyl ethyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, 1-methoxy-2-propanol, 1-methoxy-2-propyl acetate, lactic acid Methyl, ethyl lactate, dimethylsulfoxide, dimethylacetamide,
There are dimethylformamide, water, N-methylpyrrolidone, tetrahydrofurfuryl alcohol, acetone, diacetone alcohol, methanol, ethanol, isopropanol, diethylene glycol dimethyl ether and the like, and these solvents may be used alone or as a mixture. The photosensitive composition comprising these components has a solid content of 0.
5 to 3.0 g / m ^{2 is} provided.

[II] When a photosensitive layer containing a diazo resin and a water-insoluble and lipophilic photomolecular compound is provided. As the diazo resin, for example, a diazo resin inorganic salt which is a reaction product of a condensate of p-diazodiphenylamine and formaldehyde or acetaldehyde, and a hexafluorophosphate or tetrafluoroborate soluble in an organic solvent, and US Pat. No. 3,300,309, wherein said condensate and sulfonic acids such as P-toluenesulfonic acid or salts thereof, phosphinic acids such as benzenephosphinic acid or salts thereof, hydroxyl group containing compounds such as 2 , 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid or a salt thereof or the like, which is an organic solvent-soluble diazo resin organic acid salt. Other diazo resins that can be preferably used in the present invention include aromatic compounds having at least one organic group selected from a carboxyl group, a sulfonic acid group, a sulfinic acid group, an oxygen acid group of phosphorus, and a hydroxyl group, and a diazonium compound. It is a co-condensate containing a compound, preferably an aromatic diazonium compound, as a structural unit. And as the above-mentioned aromatic ring, a phenyl group and a naphthyl group can be preferably cited. The above-mentioned carboxyl group, sulfonic acid group, sulfinic acid group,
Examples of the aromatic compound containing at least one of the oxygen acid group of phosphorus and the hydroxyl group include various compounds, and preferred are 4-methoxybenzoic acid and 3-
Chlorobenzoic acid, 2,4-dimethoxybenzoic acid, p-phenoxybenzoic acid, 4-anilinobenzoic acid, phenoxyacetic acid, phenylacetic acid, p-hydroxybenzoic acid, 2,4
-Dihydroxybenzoic acid, benzenesulfonic acid, p-toluenesulfinic acid, 1-naphthalenesulfonic acid, phenylphosphoric acid, phenylphosphonic acid. As the aromatic diazonium compound constituting the constitutional unit of the co-condensed diazo resin, for example, a diazonium salt as described in JP-B-49-48001 can be used.
Particularly, diphenylamine-4-diazonium salts are preferred. Diphenylamine-4-diazonium salts are 4
-Derived from amino-diphenylamines, such 4-amine-diphenylamines include 4-amino-diphenylamines.
Aminodiphenylamine, 4-amino-3-methoxydiphenylamine, 4-amino-2-methoxydiphenylamine, 4'-amino-2-methoxydiphenylamine, 4'-amino-4-methoxydiphenylamine, 4
-Amino-3-methyldiphenylamine, 4-amino-
3-ethoxydiphenylamine, 4-amino-3-β-
Hydroxyethoxydiphenylamine, 4-amino-diphenylamine-2-sulfonic acid, 4-amino-diphenylamine-2-carboxylic acid, 4-amino-diphenylamine-2'-carboxylic acid and the like can be mentioned, with particular preference given to 3-methoxy- 4-amino-4-diphenylamine and 4-aminodiphenylamine. Further, as diazo resins other than the co-condensation diazo resin with an aromatic compound having an acid group, JP-A-4-18559 and JP-A-3-16 are available.
A diazo resin condensed with an aldehyde containing an acid group or an acetal compound thereof described in JP-A No. 3551 and JP-A-3-253857 can also be preferably used. The counter anion of the diazo resin includes an anion that stably forms a salt with the diazo resin and makes the resin soluble in an organic solvent. These include organic carboxylic acids such as decanoic acid and benzoic acid, organic phosphoric acids such as phenylphosphoric acid and sulfonic acids, and typical examples thereof include fluoroalkanesulfonic acids such as methanesulfonic acid and trifluoromethanesulfonic acid. , Laurylsulfonic acid, dioctylsulfosuccinic acid, dicyclohexylsulfosuccinic acid, camphorsulfonic acid, tolyloxy-3-propanesulfonic acid, nonylphenoxy-3-propanesulfonic acid, nonylphenoxy-4-butanesulfonic acid, dibutylphenoxy-3-propanesulfone Acid, diamylphenoxy-3-propanesulfonic acid, dinonylphenoxy-3-
Propanesulfonic acid, dibutylphenoxy-4-butanesulfonic acid, dinonylphenoxy-4-butanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, mesitylenesulfonic acid, p-chlorobenzenesulfonic acid, 2,
5-dichlorobenzenesulfonic acid, sulfosalicylic acid,
2,5-Dimethylbenzenesulfonic acid, p-acetylbenzenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-chloro-5 -Nitrobenzenesulfonic acid, butylbenzenesulfonic acid, octylbenzenesulfonic acid, decylbenzenesulfonic acid, dodecylbenzenesulfonic acid, butoxybenzenesulfonic acid, dodecyloxybenzenesulfonic acid, 2-hydroxy-4-methoxybenzophenone-
5-sulfonic acid, isopropyl naphthalene sulfonic acid,
Butylnaphthalenesulfonic acid, hexylnaphthalenesulfonic acid, octylnaphthalenesulfonic acid, butoxynaphthalenesulfonic acid, dodecyloxynaphthalenesulfonic acid, dibutylnaphthalenesulfonic acid, dioctylnaphthalenesulfonic acid, triisopropylnaphthalenesulfonic acid, tributylnaphthalenesulfonic acid, 1-naphthol -5-sulfonic acid, naphthalene-1-sulfonic acid, naphthalene-2-sulfonic acid, 1,8-dinitro-naphthalene-3,6. Aliphatic and aromatic sulfonic acids such as disulfonic acid and dimethyl-5-sulfoisophthalate, 2,
2 ', 4,4'-tetrahydroxybenzophenone,
1,2,3-trihydroxybenzophenone, 2,
Hydroxyl group-containing aromatic compounds such as 2 ', 4-trihydroxybenzophenone, halogenated Lewis acids such as hexafluorophosphoric acid and tetrafluoroboric acid, HClO ₄ , HIO ₄
Examples thereof include perhalogenic acid and the like, but are not limited thereto. Among these, butylnaphthalenesulfonic acid, dibutylnaphthalenesulfonic acid, hexafluorophosphoric acid, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and dodecylbenzenesulfonic acid are particularly preferable.

The molecular weight of the diazo resin used in the present invention can be arbitrarily determined by variously changing the molar ratio of each monomer and the condensation conditions, but is effective for the intended use of the present invention. To provide a molecular weight of about 400
100 to 100,000, preferably about 800 to 8,
000 is suitable. Examples of the water-insoluble and lipophilic polymer compound include copolymers having the structural units of the monomers shown in (1) to (15) below and having a molecular weight of usually from 100,000 to 200,000. (1) Acrylamides, methacrylamides, acrylates, methacrylates and hydroxystyrenes 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)
Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group, such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate,
4-Hydroxybutyl methacrylate (3) Unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid, (4) methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, Hexyl acrylate, cyclohexyl acrylate, octyl acrylate, benzyl acrylate,
(Substituted) alkyl acrylate such as 2-chloroethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl acrylate,

(5) (substituted) alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl methacrylate, (6) acrylamide, methacryl Amide, N-methylolacrylamide, N-methylolmethacrylamide, N-ethylacrylamide, N-hexylmethacrylamide, N-cyclohexylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide, N-ethyl- Acrylamide or methacrylamides such as N-phenylacrylamide; Vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether,
Propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, phenyl vinyl ether and other vinyl ethers, (8) vinyl acetate, vinyl chloroacetate, vinyl butyrate, vinyl benzoate and other vinyl esters, (9) styrene, α-methyl styrene, chloro Styrenes such as methylstyrene, (10) vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, phenyl vinyl ketone, etc.,

(11) Ethylene, propylene, isobutylene, butadiene, isoprene and other olefins, (12)
N-vinylpyrrolidone, N-vinylcarbazole, 4-
(13) unsaturated imides such as vinyl pyridine, acrylonitrile, methacrylonitrile (13) maleimide, N-acryloyl acrylamide, N-aceketyl methacrylamide, N-propionyl methacrylamide, N- (p-chlorobenzoyl) methacrylamide, (14) ) N (o-aminosulfonylphenyl) methacrylamide, N- (m-
Aminosulfonylphenyl) methacrylamide, N-
(P-amino) sulfonylphenyl methacrylamide,
Methacrylic acid amides such as N- (1- (3-aminosulfonyl) naphthyl) methacrylamide, N- (2-aminosulfonylethyl) methacrylamide, and acrylamides having the same substituents as described above, and o- Methacrylic acid esters such as aminosulfonylphenyl methacrylate, m-aminosulfonylphenyl methacrylate, p-aminosulfonylphenyl methacrylate, 1- (3-aminosulfonylnaphthyl) methacrylate, and acrylic acid esters having the same substituents as above. Unsaturated sulfonamide (15) N- (2- (methacryloyloxy) -ethyl) -2,3-dimethylmaleimide, vinyl cinnamate, etc., having a crosslinkable group in the side chain. Further, a monomer copolymerizable with the above monomer may be copolymerized. (16) Phenol resins described in U.S. Pat. No. 3,751,257 and polyvinyl acetal resins such as polyvinyl formal resin and polyvinyl butyral resin. (17) Japanese Patent Publication No. 54-19773 in which polyurethane is alkali-solubilized, and JP-A-57-904747
No. 60, No. 60-182437, No. 62-58242,
Polymer compounds described in JP-A Nos. 62-123452, 62-123453, 63-113450 and JP-A No. 2-146042. In addition, the above copolymer, if necessary, polyvinyl butyral resin, polyurethane resin,
Polyamide resin, epoxy resin, novolac resin, natural resin, etc. may be added.

The photosensitive composition used for the support of the present invention may further contain a dye for the purpose of obtaining a visible image by exposure and a visible image after development. Examples of the dyes include Victoria Pure Blue BOH [Hodogaya Chemical Co., Ltd.], Oil Blue # 603 [Orient Chemical Co., Ltd.], Patent Pure Blue [Sumitomo Mikuni Chemical Co., Ltd.], Crystal Violet, Brilliant Green, Ethyl Violet, Tri typified by methyl violet, methyl green, erythrosine B, basic fuchsin, malachite green, oil red, m-cresol purple, rhodamine B, auramine, 4-p-diethylaminophenyliminaphthoquinone, cyano-p-diethylaminophenylacetanilide and the like. Color tone of phenylmethane, diphenylmethane, oxazine, xanthene, iminonaphthoquinone, azomethine or anthraquinone dye from colored to colorless or different It mentioned as examples of discoloring agents changing. On the other hand, as a color changing agent which changes from colorless to colored, there are leuco dyes and, for example, triphenylamine, diphenylamine, o-chloroaniline, 1,2,3-triphenylguanidine, naphthylamine, diaminodiphenylmethane, p, p'-bis. -Dimethylaminodiphenylamine, 1,2-dianilinoethylene, p, p ', p "-tris-dimethylaminotriphenylmethane, p, p'-
Bis-dimethylaminodiphenylmethylimine, p,
p ', p "-triamino-o-methyltriphenylmethane, p, p'-bis-dimethylaminodiphenyl-4-
Examples thereof include primary or secondary arylamine dyes represented by anilinonaphthylmethane and p, p ′, p ″ -triaminotriphenylmethane. Particularly preferred are triphenylmethane dye and diphenylmethane dye. It is effectively used, and more preferably a triphenylmethane dye, particularly Victoria Pure Blue BOH.

Various additives can be further added to the photosensitive composition used for the support of the present invention. For example, alkyl ethers (such as ethyl cellulose and methyl cellulose) for improving coating properties, fluorosurfactants, nonionic surfactants (particularly preferred are fluorosurfactants), coating flexibility, resistance A plasticizer for imparting abrasion resistance (for example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate,
Trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid oligomers and polymers, of which tricresyl phosphate is particularly preferred), and an oil-sensitizing agent for improving the oil-sensitivity of the image area (for example, JP-A No. 55-527, half-esterified products of styrene-maleic anhydride copolymer with alcohol, novolak resins such as pt-butylphenol-formaldehyde resin, and 50 of p-hydroxystyrene.
% Fatty acid ester, etc.), stabilizer {eg, phosphoric acid, phosphorous acid, organic acid (citric acid, oxalic acid, dipicolinic acid, benzenesulfonic acid, naphthalenesulfonic acid, sulfosalicylic acid, 4-methoxy-2-hydroxybenzophenone- 5-sulfonic acid, tartaric acid, etc.), development accelerators (eg higher alcohols, acid anhydrides, etc.) and the like are preferably used.

In order to provide the above-mentioned photosensitive composition on a support, a predetermined amount of a photosensitive diazo resin, a lipophilic polymer compound and, if necessary, various additives are added to a suitable solvent (methyl cellosolve, ethyl Cellosolve, dimethoxyethane, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, 1-methoxy-2-propanol, methyl cellosolve acetate, acetone, methyl ethyl ketone, methanol, dimethylformamide, dimethylacetamide, cyclohexanone, dioxane,
Tetrahydrofuran, methyl lactate, ethyl lactate, ethylene dichloride, dimethyl sulfoxide, water, or a mixture thereof) to prepare a coating solution of the photosensitive composition, and then apply the solution on a support and dry it. The solvent used may be a single solvent, but it is more preferable to use a mixture of a high boiling point solvent such as methyl cellosolve, 1-methoxy-2-propanol and methyl lactate and a low boiling point solvent such as methanol and methyl ethyl ketone. The solid content concentration of the photosensitive composition at the time of application is preferably in the range of 1 to 50% by weight. In this case, the coating amount of the photosensitive composition may be about 0.2 to 10 g / m ² (dry weight), and more preferably 0.5 to 3 g / m ² .

[III] Photodimerization type photosensitive composition and light weight
When a photosensitive layer containing a compatible photosensitive composition is provided, the photodimerizable photosensitive composition may be a maleimide group or a thinner.
Mill group, cinnamoyl group, cinnamylidene group, cinnami
Side chains such as redene acetyl groups and chalcone groups, or main chains
Polymer having a maleimide group in the side chain.
As a polymer to be used, JP-A-52-988 (corresponding to US
Japanese Patent No. 4,079,041) and German Patent No. 2,
626,769, European Patent No. 21,01
No. 9, European Patent No. 3,552,
Dee Angebandute Macromolecule Kemi
(Die Angewandte Makromolekulare Chemie)115
(1983), pages 163-181.
Polymers, JP-A-49-128991 and JP-A-49-1
No. 28992, No. 49-128993, No. 50-53
No. 76, No. 50-5377, No. 50-5379, No.
No. 53-5378, No. 50-5380, No. 53-52
No. 98, No. 53-5299, No. 53-5300, No.
50-50107, 51-47940, 52-
No. 13907, No. 50-45076, No. 52-121
No. 700, No. 50-10884, No. 50-45087
Publications, German Patents 2,349,948, 2,
No. 616,276, the polymers described in each specification.
Can you name some? These polymers are
To make it soluble or swellable in water,
Acids, sulfonic acids, phosphoric acids, phosphonic acids, and their
For Lucari metal salt, ammonium salt, and alkaline water
In the polymer, dissociate acid groups with pKa of 6-12
The included ones are useful. Having the above-mentioned acid group if necessary
13 types of monomers and monomers with maleimide group
It can also be copolymerized.

The acid value of the maleimide polymer having an acid group is preferably in the range of 30 to 300, and among the polymers having such an acid value, Die Angewandte Makromolekula
re Chemie) 128 (1984), pp. 71-91, a copolymer of N- [2- (methacryloyloxy) ethyl] -2,3-dimethylmaleimide and methacrylic acid or acrylic acid. It is useful.
Furthermore, by synthesizing the vinyl monomer of the third component at the time of synthesizing the copolymer, a multi-component copolymer suitable for the purpose can be easily synthesized. For example, by using, as the vinyl monomer of the third component, an alkyl methacrylate or an alkyl acrylate whose homopolymer has a glass transition temperature of room temperature or lower, flexibility can be imparted to the copolymer.

As the photo-crosslinkable polymer having a cinnamyl group, a cinnamoyl group, a cinnamylidene group, a cinnamylidene acetyl group or a chalcone group in the side chain or the main chain thereof, US Pat. No. 3,030,208 and US Pat. 70
There are photosensitive polyesters described in each specification of 9,496 and 828,455. Examples of the photo-crosslinkable polymer solubilized in alkaline water include the following. That is, JP-A-60-1912
The photosensitive polymer as described in JP-A-44 may be mentioned. Furthermore, JP-A-62-175729
JP-A-62-175730, JP-A-63-254.
43, JP-A-63-218944, and JP-A-63-2.
The photosensitive polymer described in each publication of 18945 can be mentioned. Further, a sensitizer can be used in the photosensitive layer containing them, and as such a sensitizer, a benzophenone derivative, a benzanthrone derivative, a quinone, an aromatic nitro compound, a naphthothiazoline derivative, a benzothiazoline derivative can be used. , Thioxanthones, naphthothiazole derivatives, ketocoumarin compounds, benzothiazole derivatives, naphthofuranone compounds, pyrylium salts, and thiabilylium salts.
Such a photosensitive layer optionally contains chlorinated polyethylene, chlorinated polypropylene, polyacrylic acid alkyl ester, acrylic acid alkyl ester, acrylonitrile, vinyl chloride, styrene, a copolymer with at least one of monomers such as butadiene, Binders such as polyamide, methyl cellulose, polyvinyl formal, polyvinyl butyral, methacrylic acid copolymer, acrylic acid copolymer, itaconic acid copolymer, and dibutyl phthalate,
A phthalic acid dialkyl ester such as dihexyl phthalate, a plasticizer such as an oligoethylene glycol alkyl ester, or a phosphoric acid ester can be used.
Further, for the purpose of coloring the photosensitive layer, a dye or pigment or a pH-supporting agent as a printout agent is preferably added.

Examples of the photopolymerizable photosensitive composition include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids with aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids with aliphatic polyvalent amine compounds. And so on. As the photopolymerization initiator, vicinal polytaketaldonyl compound, α-carbonyl compound, acyloin ether, α-
Aromatic acyloin compounds substituted with hydrocarbons at positions, polynuclear quinone compounds, triallyl imidazole dimers / p
-A combination of aminophenyl ketones, benzothiazole compounds, trihalomethyl-s-triazine compounds,
Acridine and phenazine compounds, oxadiazole compounds and the like are included. Together with these, the polymer capable of forming a film in an alkali water-soluble or swellable form is benzyl (meth) acrylate / (meth) acrylic acid / necessary. Other addition polymerizable vinyl monomer copolymers, methacrylic acid / methyl methacrylate (or methacrylic acid ester) copolymers, and maleic anhydride copolymers added with pentaerythritol triacrylate by half esterification according to And acidic vinyl copolymers.

[IV] Electrophotographic Photosensitive Layer For example, a ZnO photosensitive layer disclosed in US Pat. No. 3,001,872 can be used. Also,
JP-A-56-161550, JP-A-60-18684
No. 7, JP-A-61-238063, and the like, a photosensitive layer using an electrophotographic photosensitive member may be used. The amount of the photosensitive layer provided on the support is about 0.1 to about 7 g / m ² , preferably 0.5 to 4 by dry weight after coating.
It is in the range of g / m ² .

In the method for producing a support for a lithographic printing plate according to the method of the present invention, in order to improve the adhesion between the support and the photosensitive layer, to prevent the photosensitive layer from remaining after development, or to prevent halation. For the purpose of, an intermediate layer may be provided if necessary. In order to improve the adhesiveness, the intermediate layer is generally made of a diazo resin or a phosphoric acid compound, an amino compound, a carboxylic acid compound or the like which is adsorbed on aluminum. The intermediate layer made of a highly soluble substance so that the photosensitive layer does not remain after development is generally made of a highly soluble polymer or a water-soluble polymer. Further, for antihalation, the intermediate layer generally contains a dye or a UV absorber. The thickness of the intermediate layer is arbitrary, and must be a thickness capable of performing a uniform bond-forming reaction with the upper photosensitive layer upon exposure. Usually, the coating ratio of about 1 to 100 mg / m ² on a dry solids well, 5 to 40 mg / m ² is particularly favorable.

On the coated photosensitive layer, a mat layer composed of protrusions provided independently of each other can be provided. The purpose of the mat layer is to improve the vacuum adhesion between the negative image film and the photosensitive lithographic printing plate in contact exposure, thereby shortening the vacuuming time and preventing the collapse of minute dots during exposure due to poor adhesion. That is.
As a coating method of the matte layer, there is disclosed in JP-A-55-12974.
JP-A-58-182636, a method of spraying and drying polymer-containing water described in JP-A-58-182636, and the like. It is desirable that the mat layer itself be dissolved in an aqueous alkaline developer containing substantially no organic solvent, or be removable by this.

After the photosensitive lithographic printing plate prepared as described above is exposed to an image, a resin image is formed by a process including development by a conventional method. For example, in the case of the photosensitive lithographic printing plate having the photosensitive layer of the above [I], it is exposed by imagewise exposure and then development by an aqueous alkali solution as described in US Pat. No. 4,259,434. A portion is removed to obtain a lithographic printing plate, and in the case of a photosensitive lithographic printing plate having a photosensitive layer of [II], after image exposure,
With a developer as described in U.S. Pat. No. 4,186,006, the unexposed area of the photosensitive layer is removed by development to obtain a lithographic printing plate. Also, JP-A-59-84
241, JP-A-57-192952, and JP-A-6-
It is also possible to use an aqueous alkaline developer composition used in developing a positive working lithographic printing plate as described in JP-A No. 2-24263.

[0035]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. (Example) An aluminum support of JIS1050 material was used,
It was soaked in a 10% aqueous solution of caustic soda, etched so that the amount of aluminum dissolved was 8 g / m ² , immersed in a 2% nitric acid solution for 20 seconds, desmutted, and then thoroughly washed with water. Then, in a nitric acid solution of 9 g / l at a temperature of 45 ° C.
With a waveform of 9799 and a frequency of 60 Hz, the voltage was changed so that the rise time was 1 sec, and a current waveform was created. Also, the current density is 25 A / dm ² , and as shown in Table 1,
Al concentration, anode electric quantity of alternating current, and cathode electric quantity are set to be the same, and the electric quantity of the anode is set to Q ₁ , Q ₂ , and Q _3, and Q ₁ and Q ₂
Let Q _{4 be} the amount of electricity of the cathodic electrolysis between Q ₂ and Q ₃ , and let Q _{5 be the} amount of electricity of the cathodic electrolysis between Q ₂ and Q ₃ .

[0036]

[Table 1]

After roughening under such conditions, 45
° C., to dissolve the 0.2 g / m ² of aluminum with 5% sodium hydroxide,
After being immersed in 25% sulfuric acid at 55 ° C. for 20 seconds for desmutting treatment, the SEM photograph was used to observe the grain. After that, a 2.3 g / m ² anodic oxide film was formed in 12% sulfuric acid to prepare samples (A) to (Q). The following composition was coated on the thus-prepared substrate so that the coating weight after drying was 2.0 g / m ² to form a photosensitive layer.

Photosensitive layer composition Ester compound of naphthoquinone-1,2-diazide-5-sulfonyl chloride with pyrogallol, acetone resin As described in Example 1 of US Pat. No. 3,635,709 0.75 g Cresol novolac resin 2.00 g Oil Blue 603 (Orient Chemistry) 0.04 g Ethylene dichloride 16 g 2-Methoxyethyl acetate 12 g The printing plate thus produced was passed through a transparent positive film in a vacuum baking frame with a metal halide lamp of 3 kw from a distance of 1 m. After exposure for 50 seconds, S ₁
After developing with a 5.26% aqueous solution of sodium silicate having an O ₂ / Na ₂ O molar ratio of 1.74, the stain resistance and printing durability when printing and squeezing water were confirmed. Table 2 shows the results.

[0039]

[Table 2]

In Table 2, ∘∘ is excellent in stain resistance and excellent performance, ◯ is excellent in stain resistance and excellent performance, ◯ Δ is stain resistant and practical performance, and Δ is barely practical performance,
X indicates a property that is easily soiled and has no practical use. From the above, it is possible to provide an excellent lithographic printing substrate by weaving in cathodic electrolysis for generating smut in the course of roughening with an alternating current.

[0041]

INDUSTRIAL APPLICABILITY In a method of electrochemically roughening an aluminum support by an alternating current, a uniform graining can be obtained by weaving a cathodic electrolysis for generating a smut during the roughening by the alternating current. It is possible to provide a lithographic printing plate support which is possible and is excellent in stain resistance and printing durability.

Claims (3)

[Claims] 1. A method of electrochemically roughening an aluminum web in an acidic electrolyte containing metal ions, wherein the aluminum web is roughened with an alternating current, and the web is subjected to cathodic electrolysis.
A method for producing a lithographic printing plate support, which further comprises roughening with an alternating current. 2. The method for producing a lithographic printing plate support according to claim 1, wherein the Al ions in the electrolytic solution are 0.1 g / l or more and 50 g / l or less. 3. The method for producing a lithographic printing plate support according to claim 2, wherein the quantity of electricity for cathodic electrolysis is 0.5 c / dm ^{2 to} 100 c / dm ² .