JPH01154797A - Electrolytic graining treatment of aluminum base for planography - Google Patents

Abstract

PURPOSE:To efficiently provide an aluminum alloy plate, for use as a base, with a uniform and dense pit shape, by using an alternating waveform current the polarity of which is alternately changed so that the waveform current value at the time of an anode instantaneously increases from zero to a peak current and then gradually decreases. CONSTITUTION:A cleaned aluminum plate is subjected to an electrolytic graining treatment. The waveform of an electrolyzing current used in the treatment must be an alternating waveform current the polarity of which is alternately changed and in which the waveform current value at the time of an anode instantaneously increases from zero to a peak value and then gradually decreases, whereas the waveform on the cathode side may have any shape. For obtaining a uniform pit diameter and a uniform pit distribution, it is necessary that the quantity of electricity at the time of the cathode be equal to or smaller than the quantity of electricity at the time of the anode. The gradual decrease means a decrease over a period of time longer than the rise time, the period being at least 1.5-100 times the rise time. The ratio of anode time to cathode time may vary in the range of 0.4-2.5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for electrolytically roughening an aluminum support for a lithographic printing plate, and in particular, to a method for electrolytically roughening an aluminum support for a lithographic printing plate, and in particular to a method for electrolytically roughening an aluminum support for a lithographic printing plate. , relates to an electrolytic surface roughening treatment method for obtaining an aluminum support for a lithographic printing plate having a grain in which pits are uniformly and densely present.

[Prior art]

Conventionally, aluminum plates have been widely used as supports for lithographic printing plates.In order to improve the adhesion between the support and the photosensitive layer and to provide water retention to non-image areas, the surface of the support has been roughened. The so-called graining process is carried out.

Specific methods for this graining include sandblasting,
Mechanical graining methods include boulder grain, wire grain, brush grain using a nylon brush and sanding material/water slurry, and mechanical graining methods such as spraying sanding material/water slurry onto the surface under high pressure. There is a chemical graining method in which the surface is roughened using an etching agent consisting of a mixture of. Also, Unexamined Japanese Patent Publication No. 54-
The electrochemical graining method described in JP-A No. 146234 and Japanese Patent Publication No. 48-28123, for example, the mechanical graining method and the electrochemical graining method described in JP-A-53-123204. Also known is a method that combines the mechanical graining method described in JP-A-5-6-55291 and the chemical graining method using a saturated aqueous solution of an aluminum salt of a mineral acid. .

Among the various surface roughening treatment methods described above, electrolytic surface roughening treatment using alternating current can be cited as a method that allows easy control of the shape. Furthermore, there is related prior art regarding AC power supply waveforms; for example, methods using AC in which the anode special voltage is larger than the cathode special voltage are described in Japanese Patent Publications No. 55-19191 and Japanese Patent Publication No. 56-19280. ,
A method using a waveform in which the phase of a sinusoidal alternating current is controlled by a thyristor, which is described in Japanese Patent Publication No. 57-22036,
A method using three-phase alternating current described in JP-A No. 58-157997, a method using an alternating current obtained by superimposing alternating currents with different frequencies as described in JP-A-58-207374, and JP-A-58-1989. A method using alternating current with a frequency in the range of 0, 3 to 15 Hz, which is described in Japanese Patent No. 207400, is known.

Particularly 7, although it is not in the field of printing plates,
A method using alternating current described in Publication No. 79 in which the current rapidly increases from zero to the maximum, then rapidly decreases to an intermediate value that is 1/3 to 1/2 of the maximum, and then slowly decreases to zero. , U.S. Pat. No. 3,193,485, U.S. Pat. No. 3,616,343, U.S. Pat.
No. 16346, a method of applying pulses of opposite polarity during this interval as described in U.S. Pat. A method using a waveform having .

The present inventors have investigated various power waveforms to obtain a surface with uniform and dense pits suitable for lithographic printing plates. It was not possible to obtain a pit shape.

[Purpose of the invention]

Therefore, an object of the present invention is to efficiently form a uniform and dense pit shape on an aluminum alloy plate for a support.

[Structure of the invention]

As a result of various studies to achieve the above object, the present inventors found that when roughening the surface of an aluminum plate in an electrolyte, the waveform current value at the anode instantaneously reaches a peak current from zero from zero. The inventors have discovered that the above object can be achieved by using an alternating waveform current whose polarity changes alternately such that the current value gradually decreases after a certain period of time, and has arrived at the present invention.

That is, the present invention provides a method for electrolytically roughening an aluminum support for a lithographic printing plate, in which an aluminum plate is electrolytically roughened in an electrolytic solution using an alternating waveform current whose polarity changes alternately. It is configured to use an alternating waveform current in which the alternating waveform current value instantaneously reaches a peak current value from zero, and then the current value gradually decreases.

The present invention will be explained in detail below.

The aluminum plate used as the aluminum support for a lithographic printing plate in the present invention includes an aluminum plate and an aluminum alloy plate. Various aluminum alloys can be used, such as Fe5SiSCu, Mn
, Mg, Cr5ZnSTi, PbSNi, and other metal alloys with aluminum. For example, commercially available aluminum plates include 1050 material, 1100 material, 3
An aluminum plate such as 003 material is used. Particularly preferred aluminum alloys are low purity AI and A1 alloys such as 3003.1100 material.

In the electrolytic surface roughening treatment of the present invention, it is preferable to perform a cleaning treatment for the purpose of removing fats and oils, rust, dust, etc. adhering to the surface of the aluminum plate before the treatment. This cleaning treatment includes, for example, solvent degreasing using trichlene or the like, or alkaline etching degreasing using caustic soda or the like. When degreasing with alkaline etching such as caustic soda, smut is generated, so desmut treatment (for example, 1
It is customary to further perform a treatment of immersion in 0 to 30% nitric acid.

The aluminum plate thus cleaned is then subjected to electrolytic surface roughening treatment. It is essential that the electrolytic voltage waveform used in this electrolytic surface roughening treatment reaches its peak voltage in a time when the anode special voltage is less than 1 m5ec, and then the voltage immediately decreases with time. But it's okay. However, the time for the voltage to become zero is virtually unnecessary.

The electrolytic current waveform used in the present invention is an alternating waveform current whose polarity changes alternately, and the waveform current value at the anode instantaneously reaches a peak current from zero, and then the current value gradually decreases. is essential, and as long as this is the case, the waveform on the cathode side can be of any shape. However, if the amount of electricity applied to the aluminum plate is larger at the cathode than at the anode, more reaction residues (smut) will be generated on the surface during electrolytic treatment, making it difficult to form uniform pits. This becomes a hindrance, and tends to result in uneven pits with irregular pit diameters. Further, if the amount of electricity at the cathode is zero, it becomes difficult to uniformly distribute the pits, and a fine rough surface suitable for a printing plate cannot be obtained. Therefore, in order to have uniform pit diameters and uniform distribution, the amount of electricity at the cathode needs to be the same as or smaller than the amount of electricity at the anode.

The waveforms shown in Figure 1, etc., where the anode special current does not reach the peak current instantaneously, or the waveforms shown in Figures 1 (C) and (d), where the current does not gradually decrease after reaching the peak current, indicate that the aluminum plate is of low purity. In this case, rough pits with a diameter of 10 μm or more are generated, and the unetched portion tends to increase, resulting in an uneven surface. Although the current and voltage waveform can be instantly raised to the peak voltage, the current waveform is distorted by the load of the electrolytic cell and the like. Therefore, the rise time of the current waveform to the peak current is most preferably 0 seconds, but it may have some distortion. The preferred rise time is 1 m5ec or less.

Gradual decrease here refers to a decrease over a period of time longer than the rise time, at least 1.5 times the rise time.
This means that it takes 100 times more time to decrease. The rate of decrease is preferably constant, but may be decreased stepwise.

Further, the ratio of anode time to cathode time may vary from 0.4 to 2.5.

In addition, the above alternating waveform has a current density of 10 to 200 A/dm"
A range of 10 A/dm' or more is preferable; if it is lower than 10 A/dm2, pit formation is extremely difficult to occur, and if it is 200 A/dm' or more, it becomes difficult to control uniform pit formation. The frequency is preferably in the range of 5 to 250 Hz, and if it is lower than 57, dense pit formation becomes difficult to occur.
If the frequency is higher than 50 Hz, rough pits with a diameter of 10 μm or more are likely to occur. Preferably it is 5 to 200 Hz, more preferably 10 to 120 Hz.

As the electrolytic solution used in the present invention, any one used in ordinary AC electrolytic etching can be used, but particularly preferred are an aqueous solution containing 2 to 40 g/l of nitric acid or an aqueous solution containing 2 to 40 g/l of hydrochloric acid! or an aqueous solution containing 2 to 40 g of ZIl in total. 2g/j! As the concentration becomes lower, the efficiency of roughening the surface of the aluminum plate by electrolytic etching decreases, and on the other hand, as the concentration becomes higher than 40 g/l, purely chemical etching by the acid occurs. As a result, the roughened surface becomes uneven. The temperature ranges from room temperature to 70°C, preferably from room temperature to 50°C. Further, a corrosion inhibitor such as a carboxylic acid, an amine, or an aldehyde may be included in the electrolyte.

The alternating current electrolytic surface roughening treatment according to the method of the present invention can be carried out by either batch treatment or continuous treatment.

For example, continuous processing is carried out by continuously passing an aluminum plate through an electrolytic cell and performing electrolysis between it and a counter electrode placed in the electrolytic cell.

It is preferable that the aluminum plate subjected to the electrolytic surface roughening treatment as described above is then subjected to a chemical cleaning treatment. This has the effect of removing so-called smut, which is a surface residue, from the surface.

Details of such chemical treatments are provided in U.S. Patent No. 3.834.9.
It is described in the specification of No. 98 and Japanese Unexamined Patent Publication No. 12739/1983.

When the aluminum plate thus treated is used as a support for a lithographic printing plate, it is anodized to improve water retention, adhesion with the photosensitive layer, and mechanical strength of the surface of the non-image area. An oxide film may be formed on the surface of the plate. The anodic oxidation treatment can be performed according to conventionally known methods. For example, the electrolyte is sulfuric acid, phosphoric acid, oxalic acid, amidosulfonic acid, sulfonesalicylic acid, or a mixture thereof, or an aqueous solution containing /l'+ ions, and direct current is mainly used for anodizing. It is also possible to use alternating current or a combination of these currents. Electrolyte concentration is 1-80%, temperature is 5-70℃, current density is 0.5-60 A/dm2, oxide film weight is 0.3
~5 g/m' is preferred.

The aluminum plate anodized as described above is further used in U.S. Pat. No. 2.714.066 and U.S. Pat.
No. 1.461, by immersion in an aqueous solution of an alkali metal silicate, such as sodium silicate, or as described in U.S. Pat.
As described in US Pat. It may also be treated with polyvinylphosphonic acid as described in .461.

On the lithographic printing plate support obtained in this way,
A photosensitive lithographic printing plate can be obtained by providing a conventionally known photosensitive layer as the photosensitive layer of the 28th plate (abbreviation of Pre-Sensitized Plate), and the lithographic printing plate obtained by plate-making processing is , has excellent performance.

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

■Photosensitive layer consisting of diazo resin and binder: As a negative-working photosensitive diazo compound, US Pat. No. 2.063.
Diphenylamine-p-, which is a reaction product of a diazonium salt disclosed in No. 631, No. 2.667, and No. 415 and an organic condensing agent containing a reactive carbonyl group such as aldol or acequyl; A condensation product of a diazonium salt and formaldehyde (so-called photosensitive diazo resin) is preferably used. Other useful condensed diazo compounds are Japanese Patent Publication Nos. 49-48001 and 49-4.
It is disclosed in each publication such as No. 5322 and No. 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 solution.

In addition, these water-soluble diazo compounds were
A substantially water-insoluble photosensitive product obtained by reacting with an aromatic or aliphatic compound having one or more phenolic hydroxyl groups, sulfonic acid groups, or both by the method disclosed in Publication No. 7 Polymeric diazo resins can also be used.

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

Examples of reactants with phenolic hydroxyl groups include diphenolic acids such as hydroxybenzophenone, 4,4-bis(4'-hydroxyphenyl)pentanoic acid, resorcinol, or diresorcinol, which may further contain substituents. It may have. Hydroxybenzophenone includes 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone or 2,2',4,4'-tetrahydroxybenzophenone. It will be done. Preferred sulfonic acids include benzene, toluene, xylene, naphthalene, phenol,
Examples include aromatic sulfonic acids such as sulfonic acids such as naphthol and benzophenone, or soluble salts thereof, such as ammonium and alkali metal salts. Sulfonic acid group-containing compounds may generally be substituted with lower alkyl, nitro groups, halo groups, 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, 1-naphthol-2 (or 4)-sulfonic acid, 2,4-dinitro-1-naphthol-7-sulfonic acid, 2-hydroxy-4-methoxybenzophenone-5
-sulfonic acid, sodium m (p'-anilinophenylazo)benzenesulfonate, alizarin sulfonic acid, o-toluidine-m-sulfonic acid and ethanesulfonic acid. Sulfonic esters of alcohols and their salts are also useful. Such compounds are usually readily available as anionic surfactants. Examples include ammonium or alkali metals such as lauryl sulfate, alkylaryl sulfate, p-nonylphenyl sulfate, 2-phenylethyl sulfate, isooctylphenoxyjethoxyethyl sulfate.

These substantially water-insoluble photosensitive diazo resins can be precipitated by mixing a water-soluble photosensitive diazo resin and an aqueous solution of the aromatic or aliphatic compound, preferably in approximately equal amounts. isolated.

Also preferred are the diazo resins described in GB 1.312.925.

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

The appropriate content of the diazo resin in the photosensitive layer is 5 to 50% by weight. As the amount of diazo resin decreases, photosensitivity naturally increases, but stability over time decreases. The optimum amount of diazo resin is about 8-20% by weight.

On the other hand, 11 different polymer compounds can be used as binders, but in the present invention, hydroxy,
Those containing groups such as amino, carboxylic acid, amide, sulfonamide, active methylene, thioalcohol, and epoxy are desirable. Such preferred binders include shellac as described in British Patent No. 1,350.521; Polymers containing hydroxyethyl acrylate or hydroxyethyl methacrylate units as predominant repeating units as described, polyamide resins as described in U.S. Pat. No. 3,751.257, British Patent No. 1.074
．． 392 and polyvinyl acecool resins such as polyvinyl formal resins, polyvinyl butyral resins, linear polyurethane resins as described in U.S. Pat. No. 3,660,097, 1tt resin containing polyvinyl alcohol, epoxy resin condensed from bisphenol A and epichlorohydrin, polymers containing amino groups such as polyaminostyrene and polyalmylamino (meth)acrylate, cellulose acetate, cellulose alkyl ether, Cell 0- such as cellulose acetate phthalate
This includes gas derivatives and the like.

The composition of diazo resin and binder may further include a pH indicator as described in British Patent No. 1.041.463, a pH indicator as described in U.S. Pat. No. 3.236.646. Additives such as phosphoric acid and dyes can be added.

(2) Photosensitive layer consisting of an 0-quinonediazide compound: A particularly preferred 0-quinonediazide compound is an O-naphthoquinonediazide compound, for example, U.S. Patent No. 2.766, 11
No. 8, No. 2.767, No. 092, No. 2.772.9
No. 72, No. 2.859.112, No. 2, 907.
No. 665, No. 3.046.110, No. 3.046
．． No. 111, No. 3.046.115, No. 3.04
No. 6.118, No. 3, No. 046.119, No. 3. −
No. 046.120, No. 3.046.121, No. 3
．． 046.122, 3.046.123, 3.061.430, 3.102.809, 3.106.465, 3.635.709,
It is described in many publications including the specifications of the same No. 3.647.443, and these can be suitably used. Among these, 0-naphthoquinonediazide sulfonic acid ester or 0-naphthoquinonediazidecarboxylic acid ester of an aromatic hydroxy compound, and 0-naphthoquinonediazide sulfonic acid amide or 0-naphthoquinonediazidecarboxylic acid amide of an aromatic amino compound are particularly preferred. , especially U.S. Patent No. 3.635.709
The condensation product of pyrogallol and a7tone described in the specification of No. 4 is ester-reacted with 0-naphthoquinonediazide sulfonic acid, and the product with a hydroxy group at the terminal described in the specification of U.S. Pat. No. 4.021111. 0-naphthoquinonediazide sulfonic acid, or 0-
Ester-reacted naphthoquinonediazidecarboxylic acids, homopolymers of p-hydroxystyrene as described in British Patent No. 1,494.043, or copolymers thereof with other copolymerizable monomers. ester reaction of 〇-naphthoquinonediazide sulfonic acid or 〇-naphthoquinonediazidecarboxylic acid,
To copolymers of p-aminostyrene and other copolymerizable monomers as described in U.S. Pat. No. 3,759,711. -Naphthoquinonediazide sulfonic acid or 0-naphthoquinonediazidecarboxylic acid subjected to amide reaction is very good.

Although these O-quinonediazide compounds can be used alone, it is preferable to use them in combination with an alkali-soluble resin. Suitable alkali-soluble resins include novolak-type phenolic resins, and specifically include phenol formaldehyde resins, 0-cresol formaldehyde resins, m-cresol formaldehyde resins, and the like. Further, as described in U.S. Pat. No. 4,123,279, in addition to the above-mentioned phenolic resins, phenol or cresol substituted with an alkyl group having 3 to 8 carbon atoms such as t-butylphenol formaldehyde resin can be used. It is even more preferable to use a condensate of formaldehyde and formaldehyde together. The alkali-soluble resin contains about 50 to 50% of the total weight of the composition constituting the photosensitive layer.
About 85% by weight, more preferably 60-80% by weight.

A photosensitive composition comprising an 0-quinonediazide compound includes
If necessary, dyes and plasticizers may also be added, such as those described in British Patent No. 1.
Additives can be added, such as components that provide printout performance as described in U.S. Pat. No. 041.463, U.S. Pat.

■A photosensitive layer consisting of an azide compound and a binder (for example, British Patent No. 1.235.281, British Patent No. 1.49)
Specifications of No. 5.861 and JP-A-51-32331
In addition to the compositions comprising an azide compound and a water-soluble or alkali-soluble polymer compound described in JP-A No. 51-36128, JP-A No. 50-5102 and JP-A-50-50
-84302, 50-84303, 53-12
Included are compositions consisting of a polymer containing an azide group and a polymer compound as a binder, which are described in various publications such as No. 984.

■7 Other photosensitive resin layers For example, polyester compounds disclosed in JP-A-52-96696, British Patent No. 1,112.277,
Polyvinyl cinnamate resins described in US Pat. No. 1.313.390, US Pat. No. 1.341.004, US Pat. No. 1.377, US Pat.
The photopolymerizable photopolymer compositions described in the specifications of No. 28 and No. 4.072.527 are included.

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

After the PS plate is imagewise exposed, a resin image is formed by processing including development using conventional methods.

For example, in the case of a PS plate having the photosensitive layer (1) consisting of a diazo resin and a binder, after image exposure, unexposed with a developer such as that described in U.S. Pat. No. 4,186,006. Portions of the photosensitive layer are removed by development to obtain a lithographic printing plate. In addition, in the case of a PS plate having a photosensitive layer (■), after image exposure, U.S. Patent No. 4.259.43
The exposed areas are removed by developing with an alkaline aqueous solution as described in No. 4, and a lithographic printing plate is obtained.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that "%" indicates "% by weight" unless otherwise specified.

Example 1 Aluminum plate with a thickness of 0.24 mm (material 3003)
was immersed in a 10% aqueous sodium hydroxide solution at 50° C. for 20 seconds for degreasing/cleaning, then washed with water, and then neutralized and washed with a 10% aqueous nitric acid solution. After washing with water, a nitric acid aqueous solution with a concentration of 9 g/l was used as the electrolyte, and the current density was 50 A/dm'' and a frequency of 60 Hz for 10 seconds, and the generated smut was dissolved and removed with a 20% sulfuric acid aqueous solution at 60°C.The surface condition was observed using an electron microscope. Uniform pits were densely present. This aluminum plate was anodized in a 15% sulfuric acid aqueous solution at a temperature of 30°C and a current density of 3 A/dm' so that the amount of oxide film was 2 g/m'. After washing with water, it was immersed in a 3% aqueous sodium silicate solution, washed with water, and dried.

The support thus obtained was coated with the following photosensitive liquid to provide a photosensitive layer. The dry coating amount of the photosensitive layer is 2.0 g.
It was /ba.

The obtained photosensitive lithographic printing plate was exposed through a negative image film using a metal halide lamp as a light source, developed with a standard solution of negative PS plate development DN-3C manufactured by Fuji Photo Film ■, and further gummed and lithographically printed. It was made into a version. Printing was carried out by a conventional method, and 100,000 sheets of good printed matter were obtained, with good water retention in non-image areas and no staining.

Comparative Example 1 of Photosensitive Solution Example 1 was repeated except that the current waveform of the anode current waveform (rise time 3 m5ec) shown in FIG. 1(c) was used as the current waveform of the electrolytic surface roughening treatment.

When the surface shape of this aluminum plate was observed, it was found that 10
Rough pits larger than μ were formed, and many areas remained where no pits were formed. When printing was carried out in the same manner as in Example 1 using a printing plate made using this aluminum plate, the number of printable sheets was 30,000 sheets, and the printed matter was easily stained.

Comparative Example 2 Example 1 was followed except that the anode waveform (waveform in which the peak current is maintained throughout the anode time) shown in FIG. 1(C) was used as the current waveform for electrolytic surface roughening treatment. repeated.

When the surface of this aluminum plate was observed, Comparative Example 1
It was the same.

Example 2 Example 1 was repeated except that an aqueous solution containing 5 g/l of hydrochloric acid was used as the electrolytic solution for the electrolytic surface roughening treatment.

Observation of the surface condition revealed that uniform pits with a diameter smaller than 1Oμ were formed, and the printing performance was the same as in Example 1.

Example 3 Example 1 was repeated except that the cathode current was controlled so that the ratio of the anode specific electricity amount to the cathode electricity amount was 1:0.9. Uniform pits with a diameter of 5 μm or less were densely formed on the surface of the aluminum plate. Furthermore, when printing was carried out in the same manner as in Example 1, no staining of the printed matter occurred even after printing 100,000 sheets.

Comparative Example 3 Example 1 was repeated except that the cathode current was controlled so that the ratio of the anode specific electricity amount to the cathode electricity amount was 1:1.3. The surface of the aluminum plate was non-uniform with rough pits of 10 μm or more in diameter among pits of 5 μm or less in diameter. The number of pages that can be printed is 60.
．． 000 sheets, and the printed matter is easy to get dirty,
It was inferior to that of

Comparative Example 4 Example 1 was repeated except that the AC waveform shown in FIG. 1 (6) was used for the electrolytic surface roughening treatment. When the surface of the aluminum plate was observed, rough pits with a bit diameter of 10 μm or more were formed, and the number of printable sheets was 50,000 sheets, and the printed matter was easily stained and was inferior to Example 1.

〔Effect of the invention〕

According to the present invention, when an aluminum plate is electrolytically roughened, an aluminum plate having uniform and dense fine pits suitable for a printing plate can be obtained even in the case of an aluminum alloy plate of relatively low purity.

Similar effects were also obtained when a positive photosensitive layer was used.

[Brief explanation of the drawing]

FIG. 1(a) shows an example of the current waveform used in the present invention, and FIG. 1(c) shows the rise time of the anode special current of 3 m s.
ec current waveform, (C) shows the current waveform where the peak current at the anode does not decrease with time, and (d)
Both the anode and the cathode show a so-called rectangular current waveform in which the peak current does not decrease with time.

Claims (3)

[Claims] (1) In a method for electrolytically roughening an aluminum support for a lithographic printing plate in which an aluminum plate is electrolytically roughened in an electrolytic solution using an alternating waveform current whose polarity changes alternately, the alternating waveform current at the time of the anode An electrolytic surface roughening treatment method characterized by using an alternating waveform current whose value instantly reaches a peak current value from zero and then gradually decreases. (2) The electrolytic surface roughening treatment method according to claim 1, wherein the amount of electricity at the cathode is less than the amount of electricity at the anode. (3) The electrolyte contains 2 to 40 g of nitric acid and/or hydrochloric acid
The electrolytic surface roughening treatment method according to claim 1, which is an aqueous solution containing l.