JPH09248977A - Electrolytic processing method for lithographic printing plate support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic processing method which can obtain the improvement in surface quality nonuniformity and the grains of stable honeycomb-shaped pits. SOLUTION: In an electrolytic processing method for applying electrochemical processing continuously in which an alternating current is supplied between an aluminum web 1 and counter electrodes 3a, 3b in electrolytic processing liquid composed mainly of nitric acid or hydrochloric acid containing metal ions, electrolyte 5 is supplied coutercurrently to the advance direction of the metal web 1, the flow velocity 16 of the electrolyte is made 500-4000mm/sec, and the flow velocity distribution of the electrolyte in the width direction of an electrolytic bath is regulated to be ±50% or less of the average flow velocity.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for electrolytically treating a lithographic printing plate support, and more particularly to a method for supplying an electrolytic solution between an aluminum web and a counter electrode.

[0002]

2. Description of the Related Art Aluminum plates are used as printing plate supports, especially lithographic printing plate supports. From the diversification of users, aluminum plates are close to pure aluminum.
It has been diversified to include manganese added to increase strength. In order to use such an aluminum plate as a lithographic printing plate support, it is necessary to have appropriate adhesiveness to a photosensitive material and water retention. For this purpose, the surface of the aluminum plate must be roughened so that it has uniform and fine grain. This surface roughening treatment has a significant effect on printing performance such as stain performance of the printing plate material when printing is actually performed, and its quality is an important factor in plate material manufacturing.

As a method for roughening the aluminum support for printing plates, there are a mechanical graining method, an electrochemical graining method, and the like, and the roughening is carried out by combining them in a timely manner. There is. Mechanical graining methods include, for example, ball grain, wire grain, brush grain, and liquid honing. An alternating current electrolytic etching method is generally used as the electrochemical graining method, and a special alternating current such as an ordinary sinusoidal alternating current or a rectangular wave is used as the current. In addition, as a pretreatment for the electrochemical graining, an etching treatment with caustic soda may be performed.

Among them, the AC electrolytic etching method has a problem that unlike a phenomenon caused by a DC current, a counter electrode due to carbon or metal is apt to be deteriorated. For example, when carbon is used as the counter electrode, the oxidation-reduction reaction is repeated due to the change in polarity, and the binder is severely deteriorated, and stable operation for a long time is extremely difficult. To solve such a problem, Japanese Patent Publication No. 61-48596 discloses a diode for connecting a circuit connected to a main electrode in parallel with a circuit for an auxiliary counter electrode and controlling a flow of an anode current in a main counter electrode. Alternatively, there is disclosed an electrolytic treatment apparatus characterized in that a mechanism that acts as a diode is provided in a circuit for the auxiliary counter electrode.

For example, as shown in FIG. 4, a metal web 1 as a material to be treated is supported on the inner circumference of a drum roller 2 and is connected to the opposing main counter electrodes 3a and 3b from an electrolytic solution supply port 4 through a metal. Electrolyte solution 5 containing ions is replenished and electrolyte solution outlet 6
The main electrode 3a, 3b is filled with the alternating current from the AC power source 7 to perform an electrochemical treatment, and the counter electrode with the metal web 1 is the main electrode 3a, 3b. 3b and the auxiliary counter electrode 8 to form the main counter electrode 3
A circuit for the auxiliary counter electrode 8 is connected in parallel to the circuit connected to a and 3b, a circuit in the main counter electrode of the anode current is connected in parallel, and a diode 9 or diode-like diode for controlling the flow of the anode current in the main counter electrode is connected. This is an electrolytic treatment apparatus in which a mechanism for acting is provided in a circuit for the auxiliary counter electrode 8 to flow an electric current. At this time, the main counter electrodes 3a and 3b have polarities opposite to each other, and are connected to the power source 7 on opposite sides. Further, the main counter electrodes 3a and 3b each have a large number (for example, n = 10 to 14). ) Small electrodes (3a ₁ , 3a ₂ , 3a
₃ ... 3a _n ) (3b ₁ , 3b ₂ , 3b ₃ ... 3b
_n ) are formed with the insulator 10 as a boundary, and are devised to improve current efficiency.

In the past, the electrolyte solution supply port 4 was provided at one place, so the electrolyte solution supplied from here was the metal web 1 and the electrode 3.
Between a defined narrow space between a and 3b (for example, 10
mm) through the drum roller 3 to the opposite side of the drum roller 3 and exits to the electrolyte discharge port 6. Therefore, the electrolyte is gradually fatigued by the electrolysis in the flow path, and the electrolyte is fatigued at the beginning and the end of the main counter electrode. The components differed from each other and sufficient electrolysis efficiency could not be obtained, and the temperature difference between the inlet and the outlet of the liquid became large, so that the desired grain could not be obtained. In order to improve the above-mentioned drawbacks, the applicant of the present invention discloses an electrolytic treatment apparatus characterized in that two or more electrolytic solution supply ports are first provided between counter electrodes.
No. 98 has been disclosed.

[0007]

However, even if the apparatus described in Japanese Patent Laid-Open No. 2-15198 is used, the unevenness of surface quality in the electrolytic treatment cannot be said to be sufficient, and further improvement is desired. It was rare.

It is an object of the present invention to provide an electrolytic treatment method which solves the above problems, improves the unevenness of surface quality, and obtains stable pits of honeycomb-shaped pits.

[0009]

The above object of the present invention is to continuously supply an alternating current between an aluminum web and a counter electrode in an electrolytic treatment solution mainly containing nitric acid or hydrochloric acid containing metal ions, and continuously In an electrolytic treatment method of performing an electrochemical treatment, the electrolytic solution is supplied so as to face the traveling direction of the metal web, and the flow rate of the electrolytic solution is 500 to 4000 mm.
/ Sec, a method of electrolytically treating a lithographic printing plate support. In an electrolytic treatment solution mainly composed of nitric acid or hydrochloric acid containing metal ions, an alternating current is supplied between an aluminum web and a counter electrode, and in the electrolytic treatment method of continuously performing an electrochemical treatment, electrolysis of the electrolytic solution is performed. An electrolytic treatment method for a lithographic printing plate support, characterized in that the flow velocity distribution in the width direction of the tank is regulated within an average flow velocity ± 50%. Achieved by

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, setting the flow rate of the electrolytic solution to 500 to 4000 mm / sec means 5
If the flow velocity is less than 00 mm / sec, it is not preferable because huge pits are formed in the sand, and if the flow velocity is slower than that, scale-like hydrogen gas unevenness is generated, which is not preferable in terms of surface quality, and if the flow velocity is faster than 4000 mm / sec. It is not preferable because the grain size becomes large as a whole and it is uneven and many unetched parts are generated. The flow velocity is 1000-3000 mm /
sec is more preferable. The speed of the web is 5
Although the range is 200 m / min, the effect is large at 30 m / min or more. The current density is 5 to 200 A / dm ² , and more preferably 15 to 100 A / dm ² . The distance between the electrode and the web is 5 to 50 mm, which is 5 in terms of power cost.
-20 mm is desirable.

Further, in the present invention, when the flow velocity distribution in the width direction is larger than the average flow velocity ± 30%, the graining property in the width direction is greatly changed, which causes a difference in printing performance and a base density ( (Measurement with high-sensitivity visible light sensor)
This is because a density difference of 60 mV or more occurs in the ink, and the ink presetting suitability (also referred to as “demia suitability” for a device that measures the pattern area of a printing plate and adjusts the ink supply amount) deteriorates. Particularly, the average flow velocity is preferably within ± 30%. In the present invention, in order to define the widthwise flow velocity distribution within an average flow velocity of ± 50%, a method of inserting guide vanes for increasing frictional resistance in the width direction at appropriate intervals in the width direction or the like is used. .

An embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows one embodiment in which the features of the present invention are applied to a flat type cell. The support 1 advances from left to right in the figure, and the slit of the electrolyte solution supply port 4 faces in a direction opposite to the support advancing direction. And the flow rate of the electrolytic solution is 500 to 40
It is shown to be 00 mm / sec. FIG. 1 shows an embodiment of a combination of a radial type cell and Japanese Patent Application Laid-Open No. 2-15198. Reference numeral 1 is a metal web, 2 is a radial drum roller that supports the web, and runs while maintaining a constant clearance between the web and the main counter electrodes 3a and 3b. A clearance of 5 to 50 mm is usually suitable. Further, there are two electrolytic solution supply ports 4a and 4b. In this case, in order to prevent wear of the main counter electrode, an auxiliary counter electrode and a diode can be used as described in Japanese Patent Publication No. 61-48596. The ratio between the main counter electrode and the auxiliary counter electrode differs depending on the required electrolytic etching conditions. 7 is an AC power supply, usually 0.1
An AC power supply of Hz to 500 Hz is used. The frequency varies depending on the etching pattern to be obtained, but 3
The deterioration of the main counter electrodes of a and 3b is large when the frequency is 15 Hz or less, and is particularly remarkable in the case of carbon. There are various waveforms, but Japanese Patent Publication Nos. 56-19280 and 55
It is also possible to use the special alternating waveform described in each publication of No. 19191. When a diode is used, this controls the current flowing through the auxiliary counter electrode. As a material for the auxiliary counter electrode, it is preferable to use a sintered body of platinum and magnetic iron oxide, which is resistant to deterioration. As the electrolytic solution supply port 4 of the present invention, for example, if the conventional one is 4a, the electrolytic solution supply port 4b can be provided by sandwiching the insulator 10 between the main electrodes 3a and 3b. At each electrolytic solution supply port, the electrolytic treatment solution 5 enters into the electrolytic solution supply port 4 through the supply pipe 11, and enters into the cavity 13 by the distributor 12 so as to be uniformly distributed in the entire width direction of the drum roller, and in the traveling direction of the metal web. The electrolytic cell 1 ejected from the slits 14 facing each other to the width of the electrolytic cell 15.
The flow velocity in 5 is maintained at 500 to 4000 mm / sec. 3 is equivalent to the plan view of FIG. 2, and in order to increase the uniformity in the width direction, in the supply port 4, the distributor in the width direction is shown. In order to increase the resistance of the central portion in the width direction, 12 are densely packed in the same manner as the electrolytic cell, and in the electrolytic cell 15, the guide vane 1 is also used.
7 must be installed so that they are closer to the center.
This is processed in the same way in FIG. As a result, the uniformity of the temperature of the electrolytic solution in the electrolytic cell and the stirring effect are improved, and the electrolytic efficiency is increased.

[0013]

【Example】

(Examples 1, -2, -3) The radial flow cell shown in FIG. Aluminum moving speed is 40m / min, distance between electrode and web is 2
Electricity of 250c at 0mm and current density of 50A / dm ^2.
/ Dm ² and the electrolyte flow rate condition is 500, 2,000
The flow was changed under the three conditions of 0,4,000 mm / sec.

(Comparative Examples-1 and -2) The conditions are the same as in Examples -1 to -3 except that the flow rate of the electrolytic solution is excluded, and the flow rate is 400 m /
Table 1 shows the effects of surface quality and grain shape under the flow rate of 5 conditions, where sec is Comparative Example-1 and flow rate is 5,000 mm / sec is Comparative Example-2.

[0015]

[Table 1]

From Table 1, the flow velocity of Comparative Example-1 is 400 mm / s.
ec was poor in surface quality, and the grain shape was also poor due to the presence of huge pits. Flow rate of Comparative Example-2 5000 mm / sec
The surface quality was good for a while, but it was not preferable because there were many unetched parts in the grain shape and macro pits. On the other hand, in the flow velocity range of 500 mm / sec to 4,000 mm / sec, the surface quality was good and the grain shape was uniform. When the electrolyte flow velocity increases from 500 mm / sec to 4000 mm / sec, the pit diameter also becomes relatively large.

(Examples 4 and -5 and Comparative Example 3) JIS
A1050-H16 rolled aluminum plate was mechanically roughened with a brush grain and then etched in a 25 wt% caustic soda aqueous solution at 50 ° C. to 10 g / m ² .
The smut mainly composed of aluminum hydroxide adhered to the surface of the aluminum plate was desmutted with 1.5% by weight of nitric acid, and then 40% in an aqueous solution containing 1.5% by weight of nitric acid.
℃, current speed 20A / dm ² , electricity quantity 200C / dm ²
Electrolytic surface roughening treatment is carried out with, and the portion corresponding to the edge of the pit formed by electrolytic surface roughening is etched by 1 g / m ² etching at 25% by weight of a caustic soda aqueous solution at 40 ° C. The smut mainly composed of aluminum hydroxide attached to the surface of the aluminum plate was immersed in an aqueous solution of 400 g of sulfuric acid and a liquid temperature of 60 ° C. for 10 seconds to be removed, and an oxide film was formed on the aluminum plate thus obtained. 20 g of sulfuric acid so that the amount becomes 2.5 g / m ^2.
Anodizing treatment was performed at 30 ° C. in an aqueous solution containing 0 g / liter. At that time, electrolytic surface roughening was performed with a widthwise flow velocity distribution of ± 30% and ± 50% as Examples-4 and -5, respectively, and as a comparative example-3, a flow velocity distribution of ± 55% was performed. The results are shown in Table 2.

[0018]

[Table 2]

As a result of observing the center part and the edge part with respect to the grain shape and the base concentration distribution, those having a distribution of ± 30% and ± 50% were within the acceptable range as a product, but were ± 5.
In the case of 5%, the edge portion was not etched, and the base concentration also varied, and the product was rejected.

[0020]

The electrochemistry of the present invention is controlled by making the direction of the electrolytic solution supply face the web and setting the electrolytic solution flow velocity to 500 to 4000 mm / sec, and by setting the widthwise flow velocity distribution within ± 50%. The surface quality of the static treatment process has improved even more than before, and it has become possible to obtain honeycomb-shaped pits with a stable grain pattern. Further, since the graining in the width direction in the electrolytic cell is made uniform, there is no difference in the printing performance of the aluminum support in the width direction, and the difference in the base concentration in the width direction is small, so that the demier suitability is improved.

[Brief description of drawings]

FIG. 1 is a side view of an example of a radial type cell to which the present invention is applied.

FIG. 2 is a side view of an example of a flat cell to which the present invention is applied.

FIG. 3 shows a widthwise flow velocity distribution of the present invention of ± 50 of the average flow velocity.
The top view of the Example prescribed | regulated within%.

FIG. 4 is a side view of a conventional electrolytic treatment apparatus.

[Explanation of symbols]

 1 Metal Web 2 Radial Drum Rollers 3, 3a, 3b Main Counter Electrode 4, 4a, 4b Electrolyte Supply Port 5 Electrolysis Treatment Solution 6 Electrolyte Discharge Port 7 AC Power Supply 8 Pass Roller 9 Power Supply Roller 10 Insulator 11 Supply Pipe 12 Distributor 13 Cavity 14 Slit 15 Electrolyzer 16 Electrolyte Flow Rate 17 Guide Vane

Claims (2)

[Claims] 1. An electrolytic treatment method in which an alternating current is supplied between an aluminum web and a counter electrode in an electrolytic treatment liquid mainly containing nitric acid or hydrochloric acid containing metal ions to continuously perform an electrochemical treatment, The electrolytic solution is supplied so as to face the traveling direction of the metal web, and the flow rate of the electrolytic solution is 500 to 4
A method for electrolytically treating a lithographic printing plate support, which is characterized in that it is 000 mm / sec. 2. An electrolytic treatment method in which an alternating current is supplied between an aluminum web and a counter electrode in an electrolytic treatment liquid mainly containing nitric acid or hydrochloric acid containing metal ions to continuously perform an electrochemical treatment, A method for electrolytically treating a lithographic printing plate support, characterized in that the flow velocity distribution of the electrolytic solution in the width direction in the electrolytic cell is regulated within an average flow velocity ± 50%.