JPH0798432B2 - Method for producing aluminum support for lithographic printing plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an aluminum support for a lithographic printing plate, and particularly to (a) mechanical roughening and / or chemical roughening of an aluminum plate. Of the aluminum support for a lithographic printing plate, characterized in that the treatment, (b) anodizing treatment in an aqueous solution containing sulfuric acid, and (c) electrolytic surface roughening treatment in an acidic electrolyte are performed in this order. It relates to a manufacturing method.

[Prior Art] Conventionally, an aluminum plate is widely used as a support for a lithographic printing plate, but a support is used to improve the adhesion between the support and the photosensitive layer and to impart water retention to the non-image area. A so-called graining treatment is performed to roughen the surface of the.

As a concrete means of this graining, sandblasting,
There are mechanical graining methods such as ball graining, wire graining, brush graining with nylon brush and abrasive / water slurry, honing graining by spraying abrasive / water slurry on the surface at high pressure, and alkali or acid. Alternatively, there is a chemical graining method in which the surface is roughened with an etching agent composed of a mixture thereof. Further, the electrochemical graining method described in JP-A-54-146234 and JP-B-48-28123, for example, the mechanical graining method described in JP-A-53-123204. A method combining an electrochemical graining method and a method combining a mechanical graining method described in JP-A-56-55291 and a chemical graining method using a saturated aqueous solution of a diffusing aluminum salt are also available. Are known.

Among these roughening treatment methods, electrolytic roughening treatment is a method for easily controlling the rough surface shape and obtaining a fine rough surface.

In such electrolytic surface roughening treatment, the adhesion between the support and the photosensitive layer is improved, and a large number of printable prints (hereinafter,
In order to obtain the number of printable sheets), it is sufficient to input a large amount of electricity of several hundred coulombs or more to obtain a deep grain shape, but due to the large pits of 10 μm or more generated by electrolytic surface roughening treatment. , Has a drawback that stains the non-image area. Also,
Large pits of 10 μm or more have a drawback that the number of printable sheets is reduced under high-speed or severe printing conditions such as offset rotary printing.

Further, a rough surface having small pits of 0.5 μm or less uniformly does not easily stain the non-image area at the time of printing, but has a drawback that the number of printable sheets is reduced.

[Problems to be Solved by the Invention]

Therefore, an object of the present invention is to provide a method for producing an aluminum support for a lithographic printing plate, which is less likely to cause stains on non-image areas and which has a large number of printed sheets under high-speed or severe printing conditions such as offset rotary printing. Especially.

Further, another object of the present invention is to provide a method for producing a support for a lithographic printing plate which has a large number of printed sheets with a small amount of electricity during electrolytic surface roughening treatment.

[Means for Solving the Problems]

The present inventor has conducted various studies in view of the above-described conventional techniques and problems, and as a result, after mechanically roughening and / or chemically roughening an aluminum plate, an aqueous solution containing sulfuric acid is subsequently obtained. The inventors have found that the above object can be achieved by forming an anodic oxide film therein and subsequently performing electrolytic graining treatment, and completed the present invention.

Hereinafter, the present invention will be described in detail.

The aluminum plate used in the present invention includes a pure aluminum plate and an aluminum alloy plate. Various types of aluminum alloy plates can be used, such as F
An alloy plate of a metal such as e, Si, Cu, Mn, Mg, Cr, Zn, Ti, Pb and Ni and aluminum is used. For example, as commercially available aluminum, JIS A 1050 material, 1100 material, 3003
An aluminum plate made of materials and the like is used.

In carrying out the present invention, it is preferable to first carry out a cleaning treatment for the purpose of removing oil, fat, rust, dust and the like adhering to the surface of the aluminum plate. As this cleaning treatment, for example, trichlorethylene (trichlene)
A solvent resin such as the one described above, or an alkali etching oil and fat such as caustic soda are included. When alkaline etching resin such as caustic soda is used, smut is generated, so it is customary to further perform desmut treatment (for example, dipping in 10 to 30% sulfuric acid) after washing with water to remove this. is there.

The surface of the cleaned aluminum plate is subjected to mechanical roughening and / or chemical roughening.

As the mechanical surface roughening method, any method such as brush graining, sand blasting, ball graining, wire graining, holing graining, etc. may be used, but especially since the brush graining method is capable of manufacturing stable graining. preferable. Further, a chemical surface roughening method using an alkali or an acid, or a method combining a mechanical surface roughening method and a chemical surface roughening method may be used. As the chemical surface roughening method, hydrofluoric acid / ammonium fluoride method, hydrochloric acid method, hydrochloric acid / aluminum chloride method, hydrochloric acid / iron chloride method, etc. are used, and phosphoric acid, boric acid, oxalic acid, etc. are used for these etchants. Other additives or surfactants may be added.

The surface roughness (center line average roughness) of the grained aluminum surface is preferably in the range of 0.3 to 0.7 μm. Surface roughness
If it is larger than 0.7 μm, the non-image area is likely to be stained, and conversely if the surface roughness is smaller than 0.3 μm, the number of printable sheets is reduced. As a typical example, the brush grain method, which is a mechanical surface roughening method, will be described as an example.
As the brush grain condition in the range of 3 to 0.7 μm,
The particle size of the pumice is 10 to 80 μm (average 30 μm), the water slurry is about 20%, the thickness of the nylon brush is 480 μm, the pressing pressure on the aluminum plate is 3.3 Kw, and the rotation speed is 300 rpm.

The grained aluminum plate may be washed with water and optionally etched with an alkali or an acid. The optimum amount of dissolution (etching amount) of the aluminum plate varies depending on the surface roughness of the graining, but when the surface roughness is 0.5 μm, the etching amount is preferably ² to 10 g / m ² . When the etching amount is large, the grained surface is destroyed, and the number of printable sheets is reduced. On the contrary, when the etching amount is small, the pumice remains and non-image stain occurs. As an alkaline etching condition, for example, when a dipping treatment is performed in a mixed solution of 28% by weight of sodium hydroxide and 10% by weight of aluminum ions at a temperature of 60 ° C. for 6 to 40 seconds, an etching amount of ² to 10 g / m ² is obtained. .

Generally, when alkali etching is performed, smut is generated, and therefore desmutting is performed to remove the smut. As the desmut treatment, for example, nitric acid 10
Immersion treatment in a liquid of ~ 30% by weight at a temperature of 10 ~ 30 ° C for 10 ~ 60 seconds is sufficient.

An anodized film is provided on an aluminum surface that has been mechanically and / or chemically roughened in an aqueous solution containing sulfuric acid. The thickness of the coating is preferably 0.001 to 0.5 g / m ² . 0.
Becomes smaller than 001G / m ^2, and decreases the effect of deep pits according to the invention is produced, conversely, when the thickness is more than 0.5 g / m ^2, a rough pits diameter increases.

The concentration of sulfuric acid solution in anodizing treatment is 10-500 g /
Is preferred. At a concentration lower than 10 g /, the pits generated by electrolytic surface roughening treatment become non-uniform, and conversely, at a concentration higher than 500 g / deep, deep pits are not generated. In the above sulfuric acid solution, at a current density of 0.01 to 50 A / dm ² , 0.5 to 10 coulomb / dm ²
Oxide film on the quantity of electricity to flow to the surface 0.001g / m ² ~0.5g / m ² in the range can be provided.

By providing an anodic oxide film after mechanical and / or chemical surface roughening in this way, it can be used for lithographic printing plates with a large number of printed sheets even if the amount of electricity for electrolytic surface roughening is reduced as described later. A support can be obtained.

As the electrolytic solution used for the electrolytic surface roughening treatment, any of those used for ordinary AC electrolytic etching can be used. Particularly preferred is an aqueous solution containing 2-40 g / nitric acid or a solution containing 2-40 g / hydrochloric acid, or
An aqueous solution containing 2 to 40 g / each of both. 2 g
/ As the concentration becomes lower, the efficiency of roughening the surface of the aluminum plate by electrolytic etching becomes lower, while at 40 g / higher concentration, pure chemical etching by acid occurs. As a result, roughening of the surface becomes uneven. The temperature is in the range of room temperature to 70 ° C, preferably in the range of room temperature to 50 ° C. Also,
Corrosion inhibitors such as carboxylic acids, amines and aldehydes may be added.

The current used for electrolytic surface roughening treatment is commercial alternating current or the first
Alternating waveform currents such as (a) sine wave, (b) rectangular wave, (c) trapezoidal wave, etc. shown in the figure can also be used in the present invention. The current density is preferably in the range of 10 to 200 A / dm ² , 10 A / dm ²
When it is lower than dm ² , pit formation is extremely unlikely to occur, and when it is 200 A / dm ² or more, uniform pit formation control becomes difficult. The electrolysis time varies depending on the current density, but when the current density is 10 A / dm ² , it is treated for 5 to 30 seconds and the current density is 200 A /
In the case of dm ² , processing may be performed for 1 to 4 seconds.

The present invention can be implemented by either batch processing or continuous processing. For example, in continuous treatment, a resistive film forming treatment tank, a water washing tank, and an electrolytic surface roughening treatment tank are arranged in this order, and the treatment is carried out by continuously passing through an aluminum web.

The electrolytically roughened aluminum plate is preferably chemically cleaned. This is because it has a function of removing so-called smut, which is a surface residue, from the surface. Details of such a cleaning process are described in US Pat.
No. 998, Japanese Patent Publication No. 5-11316. If necessary, the alkali etching treatment described in JP-B-48-28123 may be performed.

When the aluminum plate treated as described above is used as a support for a lithographic printing plate, water retention, adhesion to a photosensitive layer,
In order to improve the mechanical strength of the surface of the non-image area, an anodic oxidation treatment may be further performed to form an oxide film on the surface of the aluminum plate. The anodizing treatment can be performed according to a conventionally known method. For example, sulfuric acid, phosphoric acid, oxalic acid, amidosulfonic acid, sulfosalicylic acid, or a mixture thereof, or an aqueous solution containing Al ^{3 −} ions in them is used as an electrolytic solution, and anodization is mainly performed using direct current. It may be done using alternating current or a combination of these currents. Electrolyte concentration is 1-80%, temperature is 5-70 ℃,
It is preferable that the current density is 0.5 to 60 A / dm ² and the weight of the oxide film is 0.3 to 5 g / m ² .

Anodized aluminum plates are further described in US Pat.
Alkali metal silicates, such as those described in U.S. Pat.No. 066 and U.S. Pat.No. 3,181,461, such as by dipping in an aqueous solution of sodium silicate, or as described in U.S. Pat.No. 3,860,426. As described above, a subbing layer of hydrophilic cellulose (eg, carboxymethyl cellulose) containing a water-soluble metal salt (eg, zinc acetate) is provided, or polyvinyl sulfone as described in US Pat. No. 4,153,461 is used. It may be treated with an acid.

On the lithographic printing plate support thus obtained,
As a photosensitive layer of a PS plate (abbreviation of Pre-Sensitized Plate), a photosensitive layer that has been conventionally known can be provided to obtain a photosensitive lithographic printing plate. , Has excellent performance.

The composition of the above-mentioned photosensitive layer includes the following.

(A) Photosensitive layer comprising diazo resin and binder: US Pat. No. 2,062 as a negative-working photosensitive diazo compound.
Diphenylamine-p-diazonium salts and forms which are the reaction products of the diazonium salts disclosed in each of 3,631 and 2,667,415 and an organic condensing agent containing a reactive carbonyl group such as aldol and acetal. Condensation product with aldehyde (so-called photosensitive diazo resin)
Is preferably used. Other useful condensed diazo compounds are disclosed in Japanese Patent Publication Nos. 49-48001, 49-45322 and 49-45323. These types of photosensitive diazo compounds are usually obtained in the form of water-soluble inorganic salts and can therefore be coated from aqueous solutions. Further, these water-soluble diazo compounds are reacted with an aromatic or aliphatic compound having one or more phenolic hydroxyl groups, sulfonic acid groups or both by the method disclosed in Japanese Patent Publication No. 47-1167. The reaction product, a substantially water-insoluble photosensitive diazo resin, can also be used.

It can also be used as a reaction product with a hexafluorophosphate salt or a tetrafluoroborate salt as described in JP-A-56-121031.

Examples of reactants having a phenolic hydroxyl group are dibenzoic acid such as hydroxybenzophenone, 4,4-bis (4'-hydroxyphenyl) pentanoic acid, resorcinol, or diresorcinol, which are further substituted May have. Hydroxybenzophenone includes 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone or 2,2 ', 4,
Includes 4'-tetrahydroxybenzophenone. Examples of the preferable sulfonic acid include aromatic sulfonic acids such as sulfonic acids such as benzene, toluene, xylene, naphthalene, phenol, naphthol and benzophenone, and soluble salts thereof such as ammonium and alkali metal salts. The sulfonic acid group-containing compound may be generally substituted with a lower alkyl, nitro group, halo group, and / or another sulfonic acid group. Preferred examples of such compounds include benzenesulfonic acid, toluenesulfonic acid, naphthalenesulfonic acid, 2,5-dimethylbenzenesulfonic acid, sodium benzenesulfonate, naphthalene-2-sulfonic acid, and
-Naphthol-2 (or 4) -sulfonic acid, 2,4-dinitro-1-naphthol-7-sulfonic acid, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, m
-(P'-anilinophenylazo) benzenesulfonic acid sodium salt, alizarin sulfonic acid, o-toluidine-
Examples thereof include m-sulfonic acid and ethanesulfonic acid.
Sulfonic acid esters of alcohols and salts thereof are also useful. Such compounds are usually readily available as anionic surfactants. Examples thereof include ammonium or alkali metals such as lauryl sulfate, alkylaryl sulfate, p-nonylphenyl sulfate, 2-phenylethyl sulfate and isooctylphenoxydiethoxyethyl sulfate.

These substantially water-insoluble photosensitive diazo resins are isolated as a precipitate by mixing the water-soluble photosensitive diazo resin and the aqueous solution of the aromatic or aliphatic compound described above, preferably in substantially equal amounts. Be done.

Also preferred are the diazo resins described in British Patent 1,312,925.

The most preferred diazo resin is 2-methoxy-4-, a condensate of p-diazodiphenylamine and formaldehyde.
Hydroxy-5-benzoylbenzene sulfonate.

The content of the diazo resin is appropriately 5 to 50% by weight in the photosensitive layer. When the amount of diazo resin is small, the photosensitivity is naturally high, but the temporal stability is lowered. The optimum amount of diazo resin is about 8-20% by weight.

On the other hand, as the binder, various polymer compounds can be used, but in the present invention, hydroxy, amino,
Carboxylic acid, amide, sulfonamide, active methylene,
Those containing a group such as thioalcohol and epoxy are desirable. Such preferred binders include British Patent No. 1,
Polymers containing a hydroxyethyl acrylate unit or a hydroxyethyl methacrylate unit as the main repeating unit as described in Shellac described in 350,521, British Patent 1,460,978 and US Pat. No. 4,123,276. U.S. Patent No. 3,751,257
Polyamide resin described in the specification, British Patent No. 1,
074,392 phenolic resins and polyvinyl acetal resins such as polyvinyl formal resins, polyvinyl butyral resins, linear polyurethane resins described in U.S. Pat.No. 3,660,097, phthalation of polyvinyl alcohol. Resins, epoxy resins condensed from bisphenol A and epichlorohydrin, polymers containing amino groups such as polyaminostyrene and polyaluminoamino (meth) acrylate, cellulose derivatives such as cellulose acetate, cellulose alkyl ether, and cellulose acetate phthalate. To be done.

The composition comprising a diazo resin and a binder, further, a pH indicator as described in British Patent No. 1,041,463, phosphoric acid described in U.S. Pat.No. 3,236,646, an additive such as a dye. Can be added.

(B) Photosensitive layer comprising an o-quinonediazide compound: A particularly preferred o-quinonediazide compound is an o-naphthoquinonediazide compound, for example, US Pat. No. 2,766,11.
No. 8, No. 2,767,092, No. 2,772,972, No. 2,859,112
No. 2, No. 2,907,665, No. 3,046,110, No. 3,046,11
No. 1, No. 3,046, 115, No. 3, 046, 118, No. 3, 046, 1
No. 19, No. 3,046, 120, No. 3, 046, 121, No. 3, 046,
No. 122, No. 3,046,123, No. 3,061,430, No. 3,10
No. 2,809, No. 3,106,465, No. 3,635,709, No. 3,6
It is described in a large number of publications including each specification of No. 47,443, and these can be preferably used. Among these, o-naphthoquinone diazide sulfonic acid ester or o-naphthoquinone diazide carboxylic acid ester of an aromatic hydroxy compound, and o-naphthoquinone diazide carboxylic acid amide or o-naphthoquinone diazide carboxylic acid amide of an aromatic amino compound are particularly preferable. , Particularly those obtained by reacting an ester of o-naphthoquinonediazide sulfonic acid with a condensate of pyrogallol and acetone described in U.S. Pat. No. 3,635,709, at the end described in U.S. Pat.No. 4,028,111. A polyester having a hydroxy group which is ester-reacted with o-naphthoquinone diazide sulfonic acid or o-naphthoquinone diazide carboxylic acid, British Patent No. 1,494,043
Esterification of a homopolymer of p-hydroxystyrene as described in U.S. Pat. No. 6,096,048 or a copolymer of the same with other copolymerizable monomers with o-naphthoquindiazide sulfonic acid or o-naphthoquinone diazide carboxylic acid. A copolymer of p-aminostyrene and another copolymerizable monomer as described in U.S. Pat. No. 3,759,711 with o-naphthoquinone diazide sulfonic acid or o-naphthoquinone diazide carboxylic acid. The amide reaction is very good.

These o-quinonediazide compounds can be used alone, but are preferably used as a mixture with an alkali-soluble resin. Suitable alkali-soluble resins include novolac type phenol resins, and specifically include phenol formaldehyde resin, o-cresol formaldehyde resin, m-cresol formaldehyde resin and the like. Further, as described in U.S. Pat. No. 4,123,279, together with the above-mentioned phenol resin, carbon number 3 such as t-butylphenolformaldehyde resin is included.
It is even more preferable to use a condensate of phenol or cresol substituted with an alkyl group of ~ 8 and formaldehyde in combination. The alkali-soluble resin is about 50 to about 85 weight% based on the total weight of the composition constituting the photosensitive layer,
More preferably, it is contained in an amount of 60 to 80% by weight.

The photosensitive composition comprising an o-quinonediazide compound includes
Dyes, plasticizers, if necessary, such as British Patent 1,40
Additives such as components imparting printout performance can be added as described in US Pat. Nos. 1,463, 1,039,475 and US Pat. No. 3,969,118.

(C) Photosensitive layer composed of azide compound and binder (polymer compound) For example, it is described in the specifications of British Patent Nos. 1,235,281 and 1,495,861 and JP-A Nos. 51-32331 and 51-36128. In addition to a composition comprising an azide compound and a water-soluble or alkali-soluble polymer compound, JP-A-50-5102
No. 50-84302, No. 50-84303, No. 53-12984, etc., and a composition comprising a polymer containing an azide group and a polymer compound as a binder.

(D) Other photosensitive resin layers For example, polyester compounds disclosed in JP-A-52-96696, British Patent Nos. 1,112,277 and 1,313,690
No. 1,341,004, 1,377,747, etc., polyvinyl cinnamate-based resin described in each specification, U.S. Pat.
The photopolymerizable photopolymer compositions described in the specifications of 2,528 and 4,072,527 are included. or,
The case of using the electrophotographic light-sensitive material disclosed in JP-A-60-1007042 is also included.

The amount of the photosensitive layer provided on the support is about 0.1 to about 7 g / m ² ,
It is preferably in the range of 0.5 to 4 g / m ² .

The PS plate is subjected to image exposure, and then a resin image is formed by a process including development by a conventional method. For example, in the case of a PS plate having the photosensitive layer (A) consisting of a diazo resin and a binder, after image exposure, for example, US Pat. No. 4,186,006.
The unexposed portion of the photosensitive layer is removed by development with a developing solution as described in Japanese Patent Publication No. 1994-242242 to obtain a lithographic printing plate.
In the case of a PS plate having a photosensitive layer (B), after image exposure, the exposed portion is removed by developing with an alkaline aqueous solution as described in U.S. Pat. No. 4,259,434, and lithographic printing is performed. A plate is obtained.

〔The invention's effect〕

By the constitution of the present invention, that is, by mechanically roughening and / or chemically roughening an aluminum plate and then providing an anodized film in an aqueous solution containing sulfuric acid, and subsequently electrolytically roughening in an acidic electrolytic solution. It has become possible to supply a method for producing an aluminum support for a lithographic printing plate which has no contamination in the non-image area and has excellent printing durability even under high-speed or severe printing conditions such as offset rotary printing. .

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples. In addition,
"%" Indicates "% of polymerization" unless otherwise specified.

Example 1 A 0.24 mm thick aluminum plate (JIS A1050 material) was immersed in a 10% aqueous sodium hydroxide solution at 50 ° C. for 20 seconds to degrease / degrease it.
After the cleaning treatment, the plate was washed with water and then neutralized with a 10% aqueous nitric acid solution. Pumice after washing with water (particle size 10 ~ 80μ
m, average 30 μm) -water suspension (20%) was used as an abrasive, and the surface was grained (brush grain) with a rotating nylon brush (thickness 480 μm, rotation speed 300 rpm). At this time, the surface roughness (center line average roughness) was 0.5 μm. After washing with water, 1
A 0% aqueous solution of caustic soda was immersed in a solution heated to 70 ° C., and etching was performed for 12 seconds so that the amount of aluminum dissolved was 6 g / m ² . After washing with water, it was immersed in a 30% aqueous nitric acid solution at room temperature for 1 minute for neutralization, and thoroughly washed with water.

Subsequently, in a 15% (270 g /) sulfuric acid aqueous solution, anodizing treatment was performed at 1 A / dm ² , 4 clones / dm ² at room temperature, and a thin anodic oxide film (about 0.05 g / m ² ) was provided. Then, it was washed with water.

Next, using an aqueous nitric acid solution having a concentration of 9 g / electrolyte as an electrolytic solution, electrolytic surface roughening treatment was performed using the alternating waveform current shown in FIG. 1 (b). The electrolysis conditions are: frequency 60Hz, anode current density 40A / dm ²
Electrolytic surface roughening treatment was performed for 10 seconds. Then, the smut produced by the electrolytic surface roughening treatment was immersed in a 20% aqueous sulfuric acid solution at 60 ° C. for 1 minute to be dissolved and removed.

This aluminum plate was anodized in a 15% sulfuric acid aqueous solution at 30 ° C. using direct current for 1.5 minutes at 3 A / dm ^{2 so} that the weight of the anodized film was 2 g / m ^2, and after washing with water 3% sodium silicate It was immersed in an aqueous solution at 70 ° C. for 20 seconds, washed with water and dried.

A photosensitive solution having the following composition was applied to the support thus obtained and dried to form a photosensitive layer. The dry coating amount of the photosensitive layer is 2.
It was 0 g / m ² .

The photosensitive lithographic printing plate thus prepared was exposed through a negative image film using a metahalide lamp as a light source, and then developed with a standard solution of a negative PS plate developing plate DN-3 manufactured by Fuji Photo Film Co., and further gummed. Then, it was used as a lithographic printing plate.

Ink (Web King Sumi made by Toyo Ink Co., Ltd.) 30 minutes later
And dampening water (Fuji Photo Film Co., Ltd. EU-3100-fold dilution liquid) are used by Komori Printing Co., Ltd. off-wheel printing machine (new type system 18LR-418) to produce Zara from Chuetsu Pulp Co., Ltd. Printing was performed on paper at a standard printing pressure of 40,000 sheets / hour. The lithographic printing plate thus obtained had a durable printing number of 120,000. Further, there was no contamination in the non-image area.

Example 2 Example 1 was repeated except that the electrolytic surface roughening treatment on the surface provided with the anodized film before the electrolytic surface roughening treatment was performed for 5 seconds under the same conditions as in Example 1. 12 copies
It was 000 sheets. Further, there was no contamination in the non-image area.

Example 3 The method of Example 1 was followed by electrolytic surface roughening treatment, washing with water, and immersion in a 10% caustic soda aqueous solution heated to 70 ° C. for about 1 second so that the amount of aluminum dissolved was 0.5 g / m ^2. Etched. After washing with water, it was immersed in a 30% nitric acid aqueous solution for 30 seconds for neutralization, and after sufficiently washing with water, an anodized film and a photosensitive layer were further provided by the method of Example 1. When printing was carried out in the same manner as in Example 1, the number of printable sheets was 120,000. Further, there was no contamination in the non-image area.

Example 4 Electrolytic surface roughening treatment for a surface provided with an anodized film before electrolytic surface roughening treatment was performed in an electrolytic solution containing hydrochloric acid 5 g /
With the alternating waveform current shown in Fig. 2 (b), the frequency 60H
Example 1 was repeated except that the anode current density was 30 A / dm ² for 20 seconds. The printing durability was 120,000. Further, there was no contamination in the non-image area.

Comparative Example 1 The treatment described in Example 1 was performed without performing the anodizing treatment before the electrolytic surface roughening treatment. The number of printable sheets was 80,000. Contamination in the non-image area was slightly higher than in the case of Example 1.

Comparative Example 2 The treatment described in Example 2 was performed without performing the anodizing treatment before the electrolytic graining treatment. The number of printable sheets was 60,000. There was no contamination in the non-image area.

Comparative Example 3 The treatment described in Example 4 was performed without performing the anodizing treatment before the electrolytic surface roughening treatment. The number of printable sheets was 80,000. Contamination in the non-image area was slightly higher than that in Example 4.

Comparative Example 4 The treatment described in Example 1 was performed without performing mechanical graining (brush graining). The number of printable sheets was 100,000. There was no contamination in the non-image area.

Comparative Example 5 The treatments described in Example 1 were carried out except that the anodizing treatment before the electrolytic graining treatment and the electrolytic graining treatment not performed (brush grains only) were carried out. 50,000 copies
It was a sheet. The non-image area was very contaminated.

Comparative Example 6 Except that electrolytic graining treatment was performed without brush grain and anodizing treatment before electrolytic graining treatment.
The process described in Example 1 was performed. The number of printable sheets was 60,000. Contamination in the non-image area was higher than in Example 1.

Example 5 Mechanical graining treatment was performed using honing grains (aluminum oxide 40
Powder of ˜50 μm was sprayed with high-pressure water and grained. The surface roughness at this time was 0.5 μm. Example 1 was repeated except that the above was done. The number of printable sheets is 120,
It was 000. There was no contamination in the non-image area.

Example 6 Instead of the mechanical surface-roughening treatment, a chemical surface-roughening treatment (the surface-roughening treatment was carried out by immersing in a 3% ammonium fluoride aqueous solution at room temperature for 5 minutes. The surface roughness at this time was 0.5. Example 1 was repeated except that The printing durability was 120,000. There was no contamination in the non-image area.

The processing conditions and printing results of Examples 1 to 6 and Comparative Examples 1 to 6 are shown in the table.

In the above examples, the combination of the negative type photosensitive layer and the support subjected to the surface roughening treatment according to the present invention was shown, but the same effect was obtained also in the combination with the positive type photosensitive layer. .

[Brief description of drawings]

FIGS. 1 (a), (b) and (c) show voltage waveforms of alternating waveform currents used when electrolytically roughening the aluminum support of the present invention.

Claims (1)

[Claims] 1. An aluminum plate is mechanically and / or chemically roughened, and then an anodic oxide film is provided in an aqueous solution containing sulfuric acid, followed by electrolytic roughening treatment in an acidic electrolytic solution. A method for producing an aluminum support for a lithographic printing plate, comprising: