JPH1044636A - Surface roughening method for lithographic printing block aluminum substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the change of surface shape caused by the movement speed of an aluminum plate by using a triangular pulse waveform, wherein the time in which the electric current starts as 0 and reaches the peak in one cycle waveform is set within a specified percentage of the time in which the aluminum plate is kept as an anode. SOLUTION: One or more of a hydrochloric acid compound or a nitric acid compound having hydrochloric acid ions such as aluminum chloride, potassium chloride or ammonium chloride is added to approximately 1g/l-saturation into hydrochloric acid solution of approximately 1-100g/l. As the alternating current waveform used for electrochemical surface roughening, a triangular pulse waveform is used for the electrochemical surface roughening in hydrochloric acid solution. In the triangular pulse waveform, the time TP in which electric current starts as 0 and reaches the peak is set within 1-50% of the time TA in which an aluminum plate is kept as an anode. Thus the surface roughening is not affected by the change of the movement speed of the aluminum plate, and the surface shape is not changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for roughening an aluminum support used for an offset printing plate or the like.

[0002]

2. Description of the Related Art For example, in Japanese Patent Application Laid-Open No. Hei 6-13517, as a method of surface roughening of an aluminum support for a lithographic printing plate, there are mechanical roughening, chemical etching, and electrochemical roughening. (Direct or alternating current, with aqueous nitric or hydrochloric acid solutions) are described. In making such an aluminum support shape,
A series of treatments (electrochemical surface roughening using a direct current in an aqueous solution mainly containing nitric acid) + (chemical etching) + (electrochemical surface roughening using an alternating current in a nitric acid aqueous solution) The method was most advantageous in producing large undulations on the surface of the aluminum support to produce a lithographic printing plate having a uniform uneven surface profile with good printing performance.

[0003]

However, electrochemical surface roughening using a direct current with a hydrochloric acid aqueous solution in the above treatment involves a problem that the surface shape changes depending on the moving speed of the aluminum plate. It was difficult to make adjustments in terms of uniformity, which hindered production planning in particular. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to perform electrochemical surface roughening in a hydrochloric acid aqueous solution without using a direct current, so that an average diameter of about 3 to 20 μm is generated so as to be generated when a direct current is used.
It is another object of the present invention to provide a method for roughening an aluminum support for a lithographic printing plate, which can generate honeycomb-shaped pits.

[0004]

The object of the present invention is to provide a method for electrochemically roughening the surface of a continuously running aluminum plate in a hydrochloric acid aqueous solution by using an alternating current. The time TP from the time 0 reaches the peak to the peak is a waveform of one cycle, and the time TA when the aluminum plate is the anode is 1 to 1 of the time.
Achieved by using a 50% triangular wave. As the above aluminum support, an aluminum plate rolled by a continuous casting method can be used.

According to the present invention, a lithographic printing plate having excellent printing performance can be obtained by coating and drying a photosensitive layer or an intermediate layer and a photosensitive layer according to a conventional method. A mat layer may be provided on the photosensitive layer according to a conventional method. A back coat layer may be provided on the back surface for the purpose of preventing aluminum from dissolving during development. The present invention can be applied to the production of a lithographic printing plate that is processed not only on one side but also on both sides. INDUSTRIAL APPLICABILITY The present invention can be applied not only to the surface roughening of an aluminum support for a lithographic printing plate, but also to the surface roughening of any aluminum plate. As the apparatus used for the surface treatment method of the present invention, any known apparatus used for continuous surface treatment of a metal web can be applied.

The aluminum plate used in the present invention is selected from a pure aluminum plate, an alloy plate containing aluminum as a main component and a trace amount of a different element, or a plastic film on which aluminum is laminated or vapor-deposited. The different elements contained in the aluminum alloy include silicon,
Iron, nickel, manganese, copper, magnesium, chromium,
Examples include zinc, bismuth, titanium, and vanadium. Conventionally known materials described in the Aluminum Handbook 4th Edition (1990, Light Metal Association), for example, JI
SA 1050 material, JIS A 3103 material, JIS
A 3005 material, JIS A 1100 material, JIS
A 3004 material or an alloy to which 5% by weight or less of magnesium is added for the purpose of increasing the tensile strength can be used. In particular, the content of Cu is preferably 0.1% by weight or less. When the content of Cu exceeds 0.1% by weight, it is difficult to uniformly roughen the surface.

The above-mentioned aluminum plate may be manufactured by a continuous casting and rolling method in addition to an aluminum plate by a normal DC casting method. As a method of continuous casting and rolling, a twin roll method, a belt caster method, a block caster method, or the like can be used. The thickness of the aluminum plate used in the present invention is about 0.1 to 0.6 mm.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The outline of the steps for manufacturing an aluminum support for a lithographic printing plate including an embodiment of a surface roughening treatment of the present invention will be described below. (Embodiment 1) (1.a) Electropolishing treatment in an acidic aqueous solution or chemical etching treatment in an acid or alkali aqueous solution Removal of rolling oil, natural oxide film, dirt, etc. on the surface of an aluminum plate Then, the surface is treated for the purpose of uniformly performing electrochemical surface roughening. The dissolution amount of the aluminum plate is preferably 1 g / m ² to 30 g / m ² ,
It is more preferred to dissolve 〜20 g / m ² .

(1.b) Electrochemical surface roughening treatment using alternating current in an aqueous solution mainly containing hydrochloric acid Electrochemical surface roughening treatment using alternating current in an aqueous solution mainly containing hydrochloric acid Crater-like pits having an average diameter of about 0.5 to 20 μm are formed on the aluminum surface at an area ratio of 30 to 100%, and the aluminum plate surface measured with an atomic force microscope is converted to an average surface roughness of 0.35 to It is performed for the purpose of 1.0 μm. The non-image portion of the printing plate has an effect of preventing stains and improving printing durability.

(1.c) Electropolishing treatment in an acidic aqueous solution or chemical etching treatment in an acid or alkali aqueous solution In the above-mentioned (1.b), electrochemical surface roughening using alternating current is carried out. Removed the generated smut component mainly composed of aluminum hydroxide and smoothed the edges of the generated pits,
This is performed for the purpose of improving the stain performance of the printing plate. Dissolution amount of the aluminum plate is preferably set to 0.05-5 g / m ² dissolution, and more preferably 0.1 to 3 g / m ² dissolution.

(1.d) Anodizing treatment Anodizing treatment is performed to increase the abrasion resistance of the surface of the aluminum plate.

(Embodiment 2) (2.a) Electropolishing treatment in an acidic aqueous solution or chemical etching treatment in an acid or alkali aqueous solution Rolling oil, natural oxide film, dirt on the surface of an aluminum plate The treatment is performed for the purpose of removing, for example, such that electrochemical surface roughening can be performed uniformly. The dissolution amount of the aluminum plate is preferably from 1 to 30 g / m ² ,
More preferably, 20 g / m ^{2 is} dissolved.

(2.b) Electrochemical surface roughening treatment using an alternating current in an aqueous solution mainly containing hydrochloric acid Crater-like pits having an average diameter of about 0.5 to 20 μm are formed on the aluminum surface in an amount of 30 to 100%. Generated by the area ratio of
The purpose is to make the surface of the aluminum plate measured by an atomic force microscope have an average surface roughness of 0.35 to 1.0 μm.
The non-image portion of the printing plate has an effect of preventing stains and improving printing durability.

(2.c) Electropolishing treatment in an acidic aqueous solution or chemical etching treatment in an acid or alkali aqueous solution The smut produced by the electrochemical roughening of (2.b) The purpose is to dissolve the edge portions of the pits or the plateau portions where no pits are formed to obtain a surface having smooth irregularities. The non-image portion of the printing plate has an effect of preventing stains and improving printing durability. The dissolution amount of the aluminum plate is preferably 1 to 30 g / m ² ,
It is more preferable to dissolve 1.5 to 20 g / m ² .

(2.d) Electrochemical surface roughening treatment using a direct current or an alternating current in an aqueous solution mainly composed of nitric acid. Honeycomb-shaped pits having an average diameter of about 0.5 to 10 μm are formed on the aluminum surface. This is performed for the purpose of producing an area ratio of １００100%. The non-image portion of the printing plate has an effect of preventing stains and improving printing durability.

(2.e) Electropolishing treatment in an acidic aqueous solution or chemical etching treatment in an acid or alkali aqueous solution The water produced by the electrochemical roughening of (2.d) The purpose is to remove the smut component mainly composed of aluminum oxide, to smooth the edge portions of the generated pits, and to improve the stain performance of the printing plate. Dissolution amount of the aluminum plate is preferably set to 0.05-5 g / m ² dissolution, and more preferably 0.1 to 3 g / m ² dissolution.

(2.f) Anodizing treatment Anodizing treatment is performed to increase the abrasion resistance of the surface of the aluminum plate.

Next, each process of the manufacturing process of the aluminum support for a lithographic printing plate including the embodiment of the present invention will be described in more detail. A. (Electropolishing of aluminum plate in acidic aqueous solution,
Or, an aluminum plate is chemically etched in an acid or alkali aqueous solution.] An aluminum plate is electrolytically polished in an acidic aqueous solution. 21, P6
5-72 (1984) describes a formulation example of electropolishing by material. A known aqueous solution used for electropolishing can be used. An aqueous solution mainly containing sulfuric acid or phosphoric acid is preferred, and an aqueous solution mainly containing phosphoric acid is particularly preferred. Phosphoric acid 20-90% by weight (preferably 4
0-80% by weight), liquid temperature 10-90 ° C (preferably 50
To 80 ° C.), current density 1 to 100 A / dm ² (preferably 5 to 80 A / dm ² ), and electrolysis time can be selected from the range of 1 to 180 seconds. Sulfuric acid, chromic acid, hydrogen peroxide, citric acid, boric acid, hydrofluoric acid, phthalic anhydride and the like may be added to the phosphoric acid aqueous solution at 1 to 50% by weight. In addition to aluminum, an alloy component contained in an aluminum alloy may be contained in an amount of 0 to 10% by weight.

As the current, DC, pulse DC, and AC can be used, but continuous DC is preferable. As the electrolytic treatment apparatus, those used in known electrolytic treatment such as a flat type tank and a radial type tank can be used. The flow rate may be either parallel flow or counter flow with respect to the aluminum plate, and is selected from the range of 0.01 to 10000 cm / min. The distance between the aluminum plate and the electrode is 0.3
10 cm to 10 cm is preferable, and 0.8 to 2 cm is particularly preferable.

As a power supply method, a direct power supply method using a conductor roll may be used, or an indirect power supply method (liquid power supply method) without using a conductor roll may be used. As the electrode material and structure to be used, known materials used for electrolytic treatment can be used, but the cathode material is preferably carbon, and the anode material is preferably ferrite, iridium oxide or platinum. The processing surface of the aluminum plate may be the upper surface, the lower surface, or both surfaces.

Chemical Etching of Aluminum Plate in Acid or Alkaline Aqueous Solution For details of such an etching method, see US Pat.
No. 34398, and known means can be used. As the acid or alkali which can be used for the acidic aqueous solution, those described in JP-A-57-16918 and the like can be used alone or in combination. The liquid temperature is 40-90 ° C, 1-120
Preferably, the treatment is performed for seconds. The concentration of the acidic aqueous solution is 0.
The content is preferably 5 to 25% by weight, and more preferably 0.5 to 5% by weight of aluminum dissolved in the acidic aqueous solution.
The concentration of the alkaline aqueous solution is preferably 5 to 30% by weight, and the aluminum dissolved in the alkaline aqueous solution is 1% by weight.
~ 30% by weight is preferred.

After the completion of the etching process, it is preferable to carry out draining with a nip roller and washing with water to prevent the treatment liquid from being carried to the next step. When chemical etching is performed using an aqueous solution of a base, smut generally forms on the surface of aluminum,
In this case, the treatment is performed with phosphoric acid, nitric acid, sulfuric acid, chromic acid, hydrochloric acid or a mixed acid containing two or more of these acids. Further, aluminum may be dissolved in the acidic aqueous solution if it is 5% by weight or less. The liquid temperature is from 70 ℃ to 70 ℃,
The processing time is preferably from 1 to 30 seconds.

After the end of the desmutting treatment, it is preferable to perform draining with a nip roller and washing with water by spraying so as not to bring the treatment liquid to the next step. Further, an overflow waste liquid of the electrolytic solution used in the electrochemical surface roughening treatment can be used. When using the overflow waste liquid of the electrolytic solution used in the electrochemical surface roughening treatment, the water washing treatment after the desmutting treatment may be omitted, but the aluminum plate is dried so that the components in the desmutting solution do not precipitate. You need to be careful.

B. [Electrochemical surface roughening treatment using alternating current in hydrochloric acid aqueous solution] An aqueous solution mainly containing hydrochloric acid can be used for ordinary electrochemical surface roughening treatment. One or more hydrochloric acid or nitric acid compounds having hydrochloric acid ions such as aluminum chloride, sodium chloride and ammonium chloride can be added to an aqueous hydrochloric acid solution from 1 g / l to saturation. In an aqueous solution mainly composed of hydrochloric acid, iron,
Metals contained in aluminum alloys such as copper, manganese, nickel, titanium, magnesium and silica may be dissolved. Preferably, a solution in which aluminum chloride is added to a 0.5 to 2% by weight aqueous hydrochloric acid solution so that aluminum ions are 3 to 50 g / l is used. The temperature is preferably from 10 to 60C, more preferably from 20 to 50C. In electrochemical surface roughening in an aqueous solution mainly containing hydrochloric acid, cubic pits of 0.1 to 0.4 μm square are superimposed on large crater-like or honeycomb-like undulations having an average diameter of 2 to 20 μm. It is generated uniformly. Crater-like pits are 500 to 300000 pits / mm ²
It is preferable to generate at a density of

As an AC power supply waveform used for electrochemical roughening, a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave, or the like is used. Trapezoidal waves are used for electrochemical surface roughening in hydrochloric acid aqueous solution.
Sine waves and triangular waves are preferable, and trapezoidal waves and triangular waves are particularly preferable. In the trapezoidal wave and the triangular wave, the time TP until the current reaches the peak from 0 is, as shown in FIG. 2, within 50% of the time TA during which the aluminum plate is the anode in one cycle of the current waveform, and further 1 -30%, especially 1-10%
Is preferred. Similarly, for the time during which the aluminum plate is the cathode, the above-mentioned time TP is preferably within 50% of the time TC during which the aluminum electrode is the cathode.

The most preferable power supply waveform is a triangular waveform having the above characteristics. The time TH for maintaining the peak of the current waveform at the time of the anode of the aluminum plate depends on whether the aluminum plate is at the anode or the cathode in one cycle of the current waveform. 1 to 10% of a certain period TA or TC, and TP is 1 to 1 of TA or TC
A trapezoidal wave that is 50% may be used. The duty ratio is 1:
2-2: 1 is preferable, and in view of the cost of the power supply body, d
Those having a 1: 1 uty ratio are particularly preferred. The frequency is 0.1
~ 120 Hz can be used, but 20 Hz
-70 Hz is preferable in terms of equipment. The current density is preferably 10 to 200 A / dm ^{2 as} a peak value of the current waveform. The amount of electricity to be added is 10 in total of the amount of electricity that causes the anodic reaction of the aluminum plate.
0 to 1000 c / dm ² , particularly preferably 150 to 800 c / dm ² .

As the electrolytic cell used for electrochemical surface roughening using an alternating current in the present invention, an electrolytic cell used for a known surface treatment such as a vertical type, a flat type, and a radial type can be used. Particularly preferred is a radial electrolytic cell as described in JP-A-195300. The electrolytic solution passing through the electrolytic cell may be parallel or counter to the progress of the aluminum web. One or more AC power supplies can be connected to the electrolytic cell. In order to control the current ratio between the AC anode and cathode applied to the aluminum plate facing the main electrode to achieve uniform graining and to dissolve carbon at the main electrode, FIG.
It is preferable to provide the auxiliary anode 8 and shunt a part of the alternating current as described in (1). A part of the current value is transferred to the two main electrodes 3 through the rectifying elements 9a and 9b or the switching element.
By diverting the direct current to the auxiliary anode 8 provided in the auxiliary anode tank 30 different from the auxiliary anode tanks a and 3b, the current value participating in the anodic reaction acting on the aluminum web 1 facing the main electrode and the cathodic reaction are shared. The ratio with the current value can be controlled. It is preferable that the amount of electricity participating in the anodic reaction and the amount of electricity participating in the cathodic reaction acting on the aluminum web 1 facing the main electrode be 0.3 to 0.95.

C. (Electrochemical surface roughening treatment using DC or AC in nitric acid aqueous solution) In electrochemical surface roughening using DC or AC in an aqueous solution mainly containing nitric acid, the average diameter is 0.5 to 3 μm. It is preferable that pits are generated at a rate of 1 × 10 ⁵ to 1 × 10 ⁶ / mm ² . However, when the amount of electricity is relatively large, the electrolytic reaction concentrates and honeycomb pits exceeding 3 μm are also generated.

(C.1) Electrochemical surface roughening using direct current An aqueous solution mainly composed of nitric acid can be used even when a direct current is used.
A nitrate compound containing a nitrate ion such as aluminum nitrate, sodium nitrate, ammonium nitrate, etc. in an aqueous nitric acid solution of 1 to 100 g / l can be used for electrochemical surface roughening treatment using ordinary alternating current. 1 g / l or more
It can be used up to saturation. Metals contained in aluminum alloys such as iron, copper, manganese, nickel, titanium, magnesium and silica may be dissolved in the aqueous solution mainly containing nitric acid. Preferably, aluminum ion is contained in an aqueous solution of 0.5 to 2% by weight of nitric acid.
It is preferable to use a liquid to which aluminum nitrate is added so as to be 50 g / l. The temperature is preferably from 10 to 60 ° C, more preferably from 25 to 50 ° C.

As a processing apparatus used for electrochemical surface roughening using a direct current, a known apparatus using a direct current can be used. As described in Japanese Patent Application Laid-Open No. 1-141094, one or more pairs of processing apparatuses can be used. It is preferable to use a device in which the anode and the cathode are alternately arranged. Examples of known devices include Japanese Patent Application Nos. 5-68204, 6-205657, 6-21050, JP-A-61-19115, and JP-B-57-44760. Have been described.

After the completion of the electrolytic treatment, it is preferable to carry out draining with a nip roller and washing with water to prevent the treatment liquid from being carried to the next step. It is preferable to use a direct current having a ripple ratio of 20% or less as the direct current used for electrochemical surface roughening. Current density is 10-200A
/ Dm ² is preferable, and the amount of electricity when the aluminum plate is an anode is preferably 100 to 1000 C / dm ² . The anode can be selected from known electrodes for oxygen generation, such as ferrite, iridium oxide, platinum, and platinum clad or plated with a valve metal such as titanium, niobium, or zirconium. The cathode can be selected from carbon, platinum, titanium, niobium, zirconium, stainless steel, and an electrode used for a fuel cell cathode.

(C.2) Electrochemical surface roughening using alternating current As the aqueous solution mainly composed of nitric acid, an aqueous solution used for normal electrochemical surface roughening can be used. One or more nitrate compounds containing nitrate ions, such as aluminum nitrate, sodium nitrate, ammonium nitrate, etc., can be added to an aqueous nitric acid solution from 1 g / l to saturation. Metals contained in aluminum alloys such as iron, copper, manganese, nickel, titanium, magnesium and silica may be dissolved in the aqueous solution mainly containing nitric acid.
Preferably, a solution in which aluminum nitrate is added to a 0.5 to 2% by weight aqueous solution of nitric acid so that aluminum ions are 3 to 50 g / l is used. The temperature is 10
60 ° C is preferable, and 25 to 50 ° C is more preferable.

As an AC power supply waveform used for electrochemical roughening, a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave, or the like is used. For electrochemical surface roughening in an aqueous nitric acid solution, a rectangular wave or a trapezoidal wave is preferable, and a trapezoidal wave is particularly preferable. In the trapezoidal wave shown in FIG. 3, the time TP from the time when the current reaches 0 to the peak is preferably 0.5 to 3 msec. The power supply waveform used for electrochemical surface roughening in an aqueous solution mainly composed of nitric acid preferably has a duty ratio of 1: 2 to 2: 1. In view of the cost of the power supply body, the duty ratio is 1: 1. Is particularly preferred. A frequency of 0.1 to 120 Hz can be used, but a frequency of 20 to 70 Hz is preferable in terms of facilities. However, when an aluminum alloy containing more than 0.1% by weight of Cu is used for electrochemical surface roughening in an aqueous nitric acid solution, a frequency of 0.1 to 10 Hz, particularly 0.3 to 1.2 Hz is used. Preferably, an alternating current is used. Current density is 10 to 200 A / d as peak value of current waveform
m ² is preferred. The amount of electricity to be added is preferably 100 to 1000 c / dm ^{2 in} total of the amount of electricity that causes the anodic reaction of the aluminum plate.

As the electrolytic cell used for electrochemical surface roughening using alternating current in the present invention, an electrolytic cell used for a known surface treatment such as a vertical type, a flat type, and a radial type can be used. Particularly preferred is a radial electrolytic cell as described in JP-A-195300. The electrolytic solution passing through the electrolytic cell may be parallel or counter to the progress of the aluminum web. One or more AC power supplies can be connected to the electrolytic cell.

For the purpose of controlling the current ratio between the AC anode and the cathode applied to the aluminum web 1 facing the main electrode to perform uniform graining and to reduce the dissolution of carbon in the main electrodes 3a and 3b. It is preferable to provide the auxiliary anode 8 as described in 1 and shunt a part of the alternating current. By diverting a part of the current value as a DC current to the auxiliary anode 8 provided in the auxiliary anode tank 30 different from the two main electrodes 3a and 3b via the rectifying elements 9a and 9b or the switching element, Aluminum web 1 facing
The ratio of the current value participating in the anodic reaction and the current value participating in the cathodic reaction can be controlled. The amount of electricity involved in the anodic reaction and the amount of electricity involved in the cathodic reaction acting on the aluminum plate facing the main pole are 0.3
０．９0.95 is preferred.

D. (Anodic Oxidation Treatment) Anodization treatment is performed to increase the abrasion resistance of the surface of the aluminum plate. As the electrolyte used for the anodic oxidation treatment of the aluminum plate, any electrolyte that forms a porous oxide film can be used. Generally, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, or a mixture thereof is used. The concentration of these electrolytes is appropriately determined by the type of electrolyte. Anodizing treatment conditions vary depending on the electrolyte used, and thus cannot be specified unconditionally. However, generally, the concentration of the electrolyte is 1 to 80% by weight, the liquid temperature is 5 to 70 ° C., the current density is 1 to 60 A / dm ² , Voltage 1-10
It is suitable if the electrolysis time is in the range of 0 V and 10 seconds to 300 seconds. The sulfuric acid method is usually treated with a direct current,
It is also possible to use an alternating current.
A range of 10 g / m ² is appropriate. When the amount is less than 1 g / m ² , the printing durability is insufficient, and the non-image portion of the lithographic printing plate is easily damaged, and at the same time, the ink adheres to the scratched portion, that is, so-called scratch stain is easily generated. .

E. (Hydrophilic treatment after forming anodic oxide film) After the anodic oxidation treatment, the aluminum surface is subjected to a hydrophilic treatment as necessary. U.S. Pat. Nos. 2,714,066 and 31, 31 are referred to as hydrophilic treatments used in the present invention.
No. 81461, No. 3280734 and No. 3902
There is an alkali metal silicate (for example, an aqueous solution of sodium silicate) as disclosed in each of U.S. Pat.
In this method, the support is immersed in an aqueous solution of sodium silicate or electrolytically treated. In addition, Tokuboku Sho 36
No. 2,220,632, potassium fluoride zirconate, and a method of treating with polyvinyl phosphonic acid as disclosed in U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689,272. Is used. Further, after graining and anodic oxidation, sealing treatment is also preferable. Such a sealing treatment is performed by immersion in hot water and a hot aqueous solution containing an inorganic salt or an organic salt, a steam bath or the like.

F. (Others) Before the first embodiment, a mechanical surface roughening treatment using a nylon brush and a slurry liquid as described in JP-A-6-135175 may be performed. It is advantageous to mechanically roughen the surface with a rotating nylon brush roll having a hair diameter of 0.2 to 0.9 mm and a slurry supplied to the surface of the aluminum plate. Needless to say, a method of spraying a slurry liquid, a method of using a wire brush, a method of transferring the surface shape of a roll with irregularities to an aluminum plate, or the like may be used. Known abrasives can be used as the abrasive mixed in the slurry liquid, but silica sand, quartz, aluminum hydroxide or a mixture thereof is preferred.

A conventionally known photosensitive layer is provided on the lithographic printing plate support thus obtained, and a photosensitive lithographic printing plate can be obtained. The resulting lithographic printing plate has excellent performance. The photosensitive substance used in the photosensitive layer is not particularly limited, and those usually used for photosensitive lithographic printing plates can be used. For example, various types described in JP-A-6-135175 can be used. The aluminum plate is provided with an organic undercoat layer (intermediate layer) if necessary before coating the photosensitive layer. As the organic undercoat layer provided on the undercoat layer, those conventionally known can be used, and for example, those described in JP-A-9-135175 can be used. The photosensitive layer may be a negative type or a positive type.

The aluminum support before coating the photosensitive layer surface-treated in the present invention is JISZ9741-1983.
Is 85 or less. Also,
When observed with a scanning electron microscope, the average pit diameter was 0.
The portion where the honeycomb pit of 5 to 3 μm is formed accounts for 30 to 100% of the total surface area. The surface of the aluminum plate measured by an atomic force microscope has an average surface roughness of 0.35 to 1.0 μm, and the surface gradient distribution obtained by measurement with an atomic force microscope has a gradient of 30 ° or more. The ratio is 5% or more and 40% or less. AFM whose resolution in the horizontal (X, Y) direction is 0.1 μm or 1.9 μm
When the surface area determined by the approximate three-point method is a and the upper projected area is b, a value of (ab) / b × 100 (surface difference) is obtained by measuring in a measurement range of 50 μm or 240 μm square using 10 to 50. Using an AFM with a horizontal (X, Y) resolution of 0.1 μm or 1.9 μm,
The fractal dimension determined by a box counting method, a scale conversion method, a cover method, a radius of gyration method, a density correlation function method, or the like measured in a measurement range of 0 μm or 240 μm square is 2.1 to 2.5.

In the present invention, the aluminum support before coating the photosensitive layer preferably has an 85 degree glossiness specified by JIS Z9741-1983 of 30 or less.
And the amount of dampening water on the printing press exceeds the limit. When observed with a scanning electron microscope, the average pit diameter is 0.5 to 2
The proportion of a portion where honeycomb pits or crater-like pits having a thickness of 0 μm, preferably 0.5 to 3 μm occupy the entire surface area is preferably 30 to 100%, and if it is less than 30%, the surface quality of a printing plate is obtained. And the calibration work becomes difficult.

The area of the portion where the honeycomb pits or crater-like pits are formed is determined as follows. A SEM photograph at a magnification of 1500 times is taken from directly above the sample with a scanning electron microscope. Enlarge to 200% using Fuji Photo Film Co., Ltd. A transparent PET sheet is superimposed on the image enlarged and copied to 200%, and the area where the pit is generated is manually painted black. Capture the image of the PET sheet with a flatbed scanner and use Photoshop on a Macintosh
After the binarization process, the area of the portion painted black was calculated.

The average surface roughness, the specific surface area, and the ratio of the area having an inclination of 30 ° or more (a30) calculated on the basis of the three-dimensional surface shape measured by the AFM in the present invention are the blanket-like soil performance (blanket). Stain), stain resistance of the halftone non-image portion (hardness of entanglement), and printing durability. There are trade-offs with each other, but the following ranges are preferable.
AFM with a horizontal (X, Y) direction resolution of 0.1 μm
When the surface area determined by the approximate three-point method is a and the upper projected area is b, the value of a / b (specific surface area) is 1.15 to 1.50. It is particularly preferably 1.15 to 1.30. 1.15
If it is less than 1, the adhesion between the photosensitive layer and the support is poor (the printing durability is poor), and if it exceeds 1.50, the scumming performance is poor. A where the resolution in the horizontal (X, Y) direction is 1.9 μm
The average surface roughness measured in a measuring range of 240 μm square using FM is preferably from 0.35 to 1.0 μm, particularly preferably 0.3 to 1.0 μm.
5 to 0.8 μm is preferred. 0.35μ average surface roughness
If it is less than m, it becomes easy to be stained in the non-image area of the halftone dot, and
If it is larger than this, the non-image portion is easily stained in a blanket shape. It is preferable that the rate of inclination of 30 degrees or more measured in a measuring range of 240 μm square using an AFM having a resolution of 1.9 μm in the horizontal (X, Y) direction is 5 to 40%. If the ratio of the inclination of 30 degrees or more is less than 5%, the non-image portion is likely to be stained on the halftone dot, and if it is more than 40%, the non-image portion is easily stained on the blanket. The fractal dimension representing the preferred surface morphology in the present invention is 1 using an AFM with a horizontal (X, Y) resolution of 0.1 μm or 1.9 μm.
Box counting method, scale conversion method, cover method, measured in the measurement range of 00 μm square or 240 μm square,
The fractal dimension obtained by the radius of gyration method, the density correlation function method, or the like is 2.1 to 2.5.

The atomic force microscope (AFM) used for the measurement in the present invention was SP13700 manufactured by Seiko Denshi Kogyo Co., Ltd. The measurement was performed by cutting an aluminum plate cut into a size of 1 cm square on a piezo scanner. The sample was set on a horizontal sample stage, the cantilever was approached to the sample surface, and when it reached the region where the atomic force was applied, scanning was performed in the XY directions. At this time, the unevenness of the sample was captured by piezo displacement in the Z direction. Piezo scanner is XY1
Those capable of scanning 50 μm and Z 10 μm were used. The cantilever is SI-DF manufactured by NANOPROBE
20, a resonance frequency of 120 to 150 kHz and a spring constant of 1
2-20 N / m, DFM mode (Dinamic For
ce Mode). Further, the obtained three-dimensional data was subjected to least-squares approximation to correct a slight inclination of the sample, thereby obtaining a reference plane.

When the resolution in the XY directions is 1.9 μm, the measurement is performed in a 240 μm square (4 fields of 120 μm square), the resolution in the Z direction is 1 nm, and the scan speed is 60 μm.
m / sec. When the resolution in the XY directions is 0.1 μm, measurement is performed in a 50 μm square (4 fields of view in a 25 μm square), the resolution in the Z direction is 1 nm, and the scan speed is 2 nm.
It was 5 μm / sec.

The pitch of the undulation of the large waves was calculated by performing frequency analysis on the three-dimensional data. The average surface roughness is JI
This is a three-dimensional extension of the center line average roughness Ra defined in SB0601-94. The surface gradient is 3
Three adjacent points are extracted from the dimensional data, the angle between the small triangle formed by the three points and the reference plane is calculated for all the data, and a gradient distribution curve is obtained. calculate. The pit diameter of the medium wave is obtained by calculating the upper projected area S surrounded by the edge of the pit, and 2 · (S / π)
Calculate by ^1/2 . The surface area was determined by extracting three adjacent points from the three-dimensional data and calculating the total area of the small triangles formed by the three points.

[0047]

【Example】

(Example 1) The following processes were continuously performed using a JIS 1050 aluminum plate having a thickness of 0.24 mm and a width of 1030 mm by a continuous casting method. The content of Cu in this aluminum plate was 0.01% by weight. (A) The aluminum plate was subjected to an etching treatment by spraying at a sodium hydroxide concentration of 26% by weight, an aluminum ion concentration of 6.5% by weight, and a liquid temperature of 75 ° C., thereby dissolving the aluminum plate at 6.0 g / m ² . Thereafter, washing with water was performed by spraying. (B) Desmut treatment was performed by spraying with a 25% by weight aqueous solution of sulfuric acid (containing 0.5% by weight of aluminum ions) at a liquid temperature of 60 ° C., and then washed with water by spraying.

(C) Electrochemical surface roughening treatment was continuously performed using a triangular alternating current shown in Table 1 described later. The electrolytic solution at this time was a 1% by weight aqueous hydrochloric acid solution (containing 0.5% by weight of aluminum ions), and the liquid temperature was 20 ° C. The duty ratio was 1: 1. Current density is 50 A / d at peak current
m ² . Thereafter, washing with water by spraying was performed.

(D) The aluminum plate was treated with a caustic soda concentration of 5
The aluminum plate was etched at a concentration of 0.5% by weight by spraying at an aluminum ion concentration of 0.5% by weight, and the aluminum plate was dissolved at 0.1 g / m ² . The smut component mainly composed of aluminum hydroxide was removed, and the edge portion of the generated pit was dissolved to smooth the edge portion. Then, it was washed with water by spraying. (E) Desmut treatment was performed by spraying with a 25% by weight aqueous solution of sulfuric acid (containing 0.5% by weight of aluminum ions) at a liquid temperature of 60 ° C., followed by washing with water by spraying. (F) An aqueous solution of 15% by weight of sulfuric acid (containing 0.5% by weight of aluminum ions) at a liquid temperature of 35 ° C. using a DC voltage, a current density of 2 A / dm ² and an anodized film amount of 2.4 g / m 2.
Anodizing treatment was performed to obtain ² . Thereafter, washing with water by spraying was performed. (G) For the purpose of hydrophilization treatment, it was immersed in an aqueous solution of sodium silicate 2.5% by weight and 70 ° C. for 14 seconds, then washed with a spray and dried. After each treatment and washing with water, the liquid was drained with a nip roller.

[0050]

[Table 1]

Examples 1-1, 1-2, 1-3 and 1-4 were coated with an intermediate layer and a photosensitive layer and dried to obtain a negative type lithographic printing plate having a dry film thickness of 2.0 g / m ^2. It was created. When this lithographic printing plate was printed, it was a good printing plate.

(Example 2) Thickness 0.24 mm, width 103
The following treatment was performed using a 0 mm JIS 1050 aluminum plate by a continuous casting method. The content of Cu in this aluminum plate was 0.01% by weight. (A) An aluminum plate is subjected to an etching treatment by spraying at a concentration of 26% by weight of caustic soda, a concentration of 6.5% by weight of aluminum ion and a liquid temperature of 75 ° C., dissolving the aluminum plate by 6.0 g / m ² , rolling oil and natural oxidation The film was removed. Thereafter, washing with water was performed by spraying. (B) Desmut treatment with a 1% by weight aqueous solution of hydrochloric acid (containing 0.5% by weight of aluminum ion) at a liquid temperature of 30 ° C. was performed by spraying, followed by washing with water by spraying.
As the aqueous hydrochloric acid solution used for the desmutting, a waste liquid from a step of performing electrochemical surface roughening using an alternating current in an aqueous hydrochloric acid solution was used.

(C) Electrochemical surface roughening treatment was continuously performed using a triangular alternating current having a frequency of 30 Hz. At this time, the electrolytic solution was a 1% by weight aqueous hydrochloric acid solution (containing 0.5% by weight of aluminum ions), and the liquid temperature was 25 ° C. The AC power supply waveform has a time T until the current value reaches a peak from zero.
Electrochemical surface-roughening treatment was performed using a triangular wave having a P of 2 msec and a duty ratio of 1: 1 with a carbon electrode as a counter electrode. Current density is 50A / dm at peak current
^{2. The} quantity of electricity was 400 C / dm ^{2 as} the sum of the quantity of electricity when the aluminum plate was the anode. Thereafter, washing with water by spraying was performed.

(D) The aluminum plate was treated with caustic soda concentration 2
The aluminum plate was subjected to an etching treatment by spraying at 6% by weight, an aluminum ion concentration of 6.5% by weight and a liquid temperature of 75 ° C. to dissolve the aluminum plate at 5 g / m ² , and then washed with water by spraying. (E) Desmut treatment with a 1% by weight aqueous solution of nitric acid (containing 0.5% by weight of aluminum ions) at a liquid temperature of 30 ° C. was performed by spraying, and then, washing with water was performed by spraying.
As the nitric acid aqueous solution used for the desmutting, a waste liquid from a step of performing electrochemical surface roughening using an alternating current in a nitric acid aqueous solution was used.

(F) Electrochemical surface roughening treatment was performed continuously using an AC voltage of 60 Hz. The electrolyte used at this time was a 1% by weight aqueous solution of nitric acid (containing 0.5% by weight of aluminum ion and 0.007% by weight of ammonium ion) at a temperature of 45 ° C. In the AC power supply waveform, the time TP required for the current value to reach a peak from zero is 1.0 msec, dut
Electrochemical surface roughening treatment was performed using a trapezoidal rectangular wave alternating current having a y ratio of 1: 1 and a carbon electrode as a counter electrode. The current density is 50 A / dm ² at the peak value of the current, and the amount of electricity is 230 C / d as the sum of the amount of electricity when the aluminum plate is the anode.
m ² . Thereafter, washing with water by spraying was performed.

(G) The aluminum plate was treated with a caustic soda concentration of 5
The aluminum plate is etched by spraying at a concentration of 0.5% by weight aluminum ion at a concentration of 0.5% by weight, the aluminum plate is dissolved at 1.0 g / m ² , and the aluminum plate is formed when the surface is electrochemically roughened by using the preceding alternating current. The smut component mainly composed of aluminum hydroxide was removed, and the edge portion of the generated pit was dissolved to smooth the edge portion. Then, it was washed with water by spraying. (H) Desmut treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid (containing 0.5% by weight of aluminum ions) at a liquid temperature of 60 ° C., followed by washing with water by spraying. (I) An aqueous solution of 15% by weight of sulfuric acid (containing 0.5% by weight of aluminum ion) at a solution temperature of 35 ° C. using a DC voltage, a current density of 2 A / dm ² and an anodized film amount of 2.4 g / m 2.
Anodizing treatment was performed to obtain ² . Thereafter, washing with water by spraying was performed. (J) For the purpose of hydrophilization treatment, the substrate was immersed in an aqueous solution of sodium silicate 2.5% by weight: 70 ° C. for 14 seconds, washed with water by a spray, and dried. After each treatment and washing with water, the liquid was drained with a nip roller.

When the surface of the treated aluminum plate was observed with a JEOL FESEM, honeycomb pits having an average diameter of 0.5 to 3 μm were superimposed on large undulations of 5 to 30 μm. The intermediate layer and the photosensitive layer were applied to this aluminum plate and dried to prepare a negative lithographic printing plate having a dry film thickness of 2.0 g / m ² . Printing was performed using this lithographic printing plate, and a good printing plate was obtained.

(Example 3) Width 1030 having a thickness of 0.3 mm
The treatment was continuously performed using a JIS JIS1050 aluminum plate by a continuous casting method of mm. The content of Cu in this aluminum plate was 0.01% by weight. (A) While supplying a suspension of an abrasive (aluminum hydroxide) having a specific gravity of 1.12 and water as a polishing slurry to the surface of an aluminum plate, mechanically roughening is performed by a rotating roller-shaped nylon brush. Was. The nylon brush was made of nylon 6/10, and had a bristle length of 50 mm and a bristle diameter of 0.48 mm. Nylon brush is Φ30
A hole was made in a 0 mm stainless steel cylinder and the hairs were densely planted. Three rotating brushes were used. 2 at the bottom of the brush
The distance between the book support rollers (Φ200 mm) was 300 mm. The brush roller was pressed until the load of the drive motor for rotating the brush became 7 kW plus the load before pressing the brush roller against the aluminum plate. The direction of rotation of the brush was the same as the direction of movement of the aluminum plate. (B) The aluminum plate was spray-etched at a sodium hydroxide concentration of 26% by weight, an aluminum ion concentration of 6.5% by weight and a liquid temperature of 75 ° C. to dissolve 15 g / m ^{2 of the} aluminum plate. Thereafter, washing with water was performed by spraying. (C) A desmutting treatment was performed by spraying with a 1% by weight aqueous solution of hydrochloric acid (containing 0.5% by weight of aluminum ion) at a liquid temperature of 20 ° C., and then washed with water by spraying.
As the aqueous hydrochloric acid solution used for the desmutting, a waste liquid from a step of performing electrochemical surface roughening using an alternating current in an aqueous hydrochloric acid solution was used.

(D) Electrochemical surface roughening treatment was continuously performed using a triangular wave alternating current having a frequency of 60 Hz. At this time, the electrolytic solution was a 1% by weight aqueous hydrochloric acid solution (containing 0.5% by weight of aluminum ions), and the liquid temperature was 25 ° C. The AC power supply waveform has a time T until the current value reaches a peak from zero.
P is 1 msec, duty ratio is 1: 1, using a triangular wave,
Electrochemical surface roughening treatment was performed using a carbon electrode as a counter electrode. The current density is 50 A / dm ² at the peak value of the current,
The quantity of electricity is the sum of the quantity of electricity when the aluminum plate is the anode, 20
It was 0 C / dm ² . Thereafter, washing with water by spraying was performed.

(E) The aluminum plate was treated with a caustic soda concentration of 5
Wt%, an aluminum ion concentration of 0.5 wt% was etched by spraying the aluminum plate 0.1 g / m ² was dissolved, generated when subjected to electrochemical surface roughening by using alternating current in the prior step The smut component mainly composed of aluminum hydroxide was removed, and the edge portion of the generated pit was dissolved to smooth the edge portion. Then, it was washed with water by spraying. (F) Desmut treatment was performed by spraying with a 25% by weight aqueous solution of sulfuric acid (containing 0.5% by weight of aluminum ions) at a liquid temperature of 60 ° C., and then washing with water was performed by spraying. (G) An aqueous solution of 15% by weight of sulfuric acid (containing 0.5% by weight of aluminum ion) at a liquid temperature of 35 ° C., a DC voltage, a current density of 2 A / dm ² and an anodized film amount of 2.4 g / m 2.
Anodizing treatment was performed to obtain ² . Thereafter, washing with water by spraying was performed. (H) For the purpose of hydrophilic treatment, the substrate was immersed in an aqueous solution of sodium silicate (2.5% by weight) at 70 ° C. for 14 seconds, washed with water by a spray, and dried. After each treatment and washing with water, the liquid was drained with a nip roller.

When the surface of the treated aluminum plate was observed with a JEOL FESEM, honeycomb pits having an average diameter of 2.0 to 3.0 μm were superimposed on large undulations of 5 to 30 μm. Further, fine cubic pits formed in the aqueous hydrochloric acid solution were formed on the surface. Apply the intermediate layer and photosensitive layer to this aluminum plate,
After drying, a negative planographic printing plate having a dry film thickness of 2.0 g / m ² was prepared. Printing was performed using this lithographic printing plate, and a good printing plate was obtained.

(Other Possible Applications) The present invention can be applied to roughening of any aluminum plate and aluminum foil.

[0063]

The characteristics based on the specific measurement method used in the present invention are effective, and the time TP until the current reaches a peak from 0 using an alternating current in an aqueous hydrochloric acid solution by the surface roughening method of the present invention. By using a triangle of 1 to 50% of the time when the aluminum plate is the anode with a waveform of one cycle, the surface roughness of the electrochemical surface roughening using a direct current is not affected by the change in the moving speed of the aluminum plate. Thus, honeycomb-shaped pits having a relatively large average diameter of 3 to 20 μm can be generated. The diameter can be determined by the frequency and the quantity of electricity.

[Brief description of the drawings]

FIG. 1 is a side view showing a radial electrolytic apparatus according to one embodiment using an alternating current of a surface roughening treatment of the present invention.

FIG. 2 is a diagram of an alternating current waveform (triangular wave) used in an aqueous solution mainly containing hydrochloric acid used in an embodiment of the present invention.

FIG. 3 is a diagram of an alternating current waveform (trapezoidal wave) used in an aqueous solution mainly containing nitric acid or hydrochloric acid used in an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum web 2 Radial drum roller 3a, 3b Main electrode 4 Electrolytic treatment liquid 5 Electrolyte supply port 6 Slit 7 Electrolyte passage 8 Auxiliary anode 9a, 9b Thyristor 10 AC power supply 20 Main electrolytic cell 30 Auxiliary anode tank

Claims (2)

[Claims] 1. A method for electrochemically roughening the surface of a continuously running aluminum plate using an alternating current in an acidic aqueous solution, wherein a time TP until the current reaches a peak from 0 is one cycle. The time TA during which the aluminum plate is the anode in the waveform of 1 to 50
% Of a triangular wave, wherein the aluminum support for a lithographic printing plate is roughened. 2. The method for roughening a surface of an aluminum support for a lithographic printing plate according to claim 1, wherein the aluminum support is an aluminum plate rolled by a continuous casting method.