JPH0379800A - Electrolytic treating method - Google Patents

Abstract

PURPOSE:To easily produce an Al sheet having a pit deep enough as compared with its diameter on the surface of an Al support and appropriate as the printing plate support by forming the counter electrode for the Al support with the main counter electrode and auxiliary counter electrode of specified structure at the time of roughening the surface of the printing plate Al support by chemical etching. CONSTITUTION:An Al web 6 as a printing plate Al support is passed by guide rolls 7 and 9 through an electrolyte 10 contg. nitric acid and Al in an electrolytic cell 9, an anode current is applied from a power source 4 between the web and the counter electrode formed with the main counter electrode consisting of graphite electrodes 1 and 2 and the auxiliary electrode 3, and the surface of the web 6 is roughened by etching. In this case, the auxiliary electrode 3 is connected in parallel with the main electrodes 1 and 2 and acts as a diode for controlling the current to the main counter electrodes 1 and 2. Uniform and deep pits are formed on the surface of the web 6 by applying an AC current of specified waveform, and the surface is appropriately roughened as the printing plate support.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrolytic treatment method for electrochemically roughening a metal plate, and in particular to an electrolytic treatment method for an aluminum support for a printing plate. It is related to.

[Conventional technology]

As a printing plate support, especially as a support for offset printing plates,
Aluminum plates (including aluminum alloy plates) are used.

Generally, in order to use an aluminum plate as a plate material (support) for offset printing, it is necessary that the aluminum plate has appropriate adhesion to the photosensitive material and water retention.

For this purpose, the aluminum plate must be roughened so that the surface has a uniform and dense grain. Since this surface roughening treatment has a significant effect on the printing performance and printing durability of the plate material when printing is actually performed after plate making, its quality is an important factor in the production of the plate material.

AC electrolytic etching is generally used as a method for roughening aluminum supports for printing plates, and the current used is a special alternating waveform current such as an ordinary sine wave alternating current or a rectangular wave. There is.

Then, using a suitable electrode such as graphite as a counter electrode, the surface of the aluminum plate is roughened by alternating current, which is usually carried out in one cycle. However, the bit depth obtained by such a method was generally shallow, and the printing durability was poor. For this reason, a number of methods have been proposed in order to obtain an aluminum plate suitable as a printing plate support by uniformly and densely distributing bits that are deep compared to its diameter.

Examples of this method include a surface roughening method using a special electrolytic power supply waveform (Japanese Patent Application Laid-Open No. 53-67507), and a method that sets the ratio of the amount of electricity between the anode and cathode during electrolytic surface roughening using alternating current. method (Japanese Unexamined Patent Publication No. 54-65607), method using special power supply waveform (Japanese Unexamined Patent Publication No. 55-253a 1)
, a method based on a combination of the amount of current per area at IN (
Japanese Unexamined Patent Publication No. 56-29699) is known.

In addition to roughening the surface of aluminum supports for printing plates, these technologies have also been put to practical use in a wide range of applications, including electrolytic etching and electrolytic coloring of iron, etc., and the power source used is Direct current, for the purpose of improving quality and reaction efficiency.
Commercial alternating current, other special waveforms controlled by thyristors, square wave alternating current, etc. are used.

FIG. 4 shows a schematic diagram of an apparatus for electrolytically roughening an offset printing plate using a conventional system.

1.2 is a graphite electrode serving as a main counter electrode, 3 is an auxiliary counter electrode, and since current flows through the diode 5, only an anode current flows. 4 is the power supply, commercial AC.

Square waves, etc. are determined according to the desired quality level.
FIG. 5 shows the current waveform. 6 is an aluminum web 6; 7 is a guide roll that supports the aluminum web 6;
8 is an insulator that prevents current from flowing into the adjacent graphite electrode 1.2; 9 is an electrolytic cell;
0 is an electrolytic solution, and in the case of an offset printing plate, a solution mainly containing nitric acid or hydrochloric acid is used.

In such a configuration, the graphite electrode 1.2 is used as the main counter electrode.
When applying QIA <Q' FA + Qp
.

Q, A>Q'de, that is, (Qy^= Q' FA
+Qp) is the condition to prevent the graphite electrode from melting, and for this reason, special waveforms Q and A as shown in Figure 5 are created.
> Q, A [Problems to be solved by the invention] However, the power supply that generates the special waveform shown in Fig. 5 has a complicated electric circuit, the power supply equipment is large, and the cost is high. It had the disadvantage that the device was prone to biased magnetism, which required complicated control for countermeasures.

Also, when QFA > CIA, in the case of a symmetrical waveform in FIG. 5, T, > 1. As a result, there is a difference in electrode reaction between the graphite electrodes 1 and 2 shown in FIG. 4 and the aluminum web, resulting in a drawback that uniform surface roughening treatment cannot be performed.

The purpose of the present invention was to solve the above-mentioned drawbacks, and it is an object of the present invention to provide an electrolytic treatment method that can uniformly roughen the surface and also eliminate the need for complicated power supply equipment and reduce costs. .

[Means and effects for solving the problem] The present inventors,
As a result of extensive research to solve the above problems, we have developed an electrolytic treatment method in which an alternating current is supplied between the material to be treated and a counter electrode in an electrolytic treatment solution to electrochemically treat the material to be treated. the counter electrode is formed by a main counter electrode and an auxiliary counter electrode, a circuit connected to the main counter electrode is connected in parallel with a circuit for the auxiliary counter electrode, and a diode or a diode is provided for controlling the flow of the anode current in the main counter electrode. An electrolytic treatment method characterized in that a mechanism that acts as an auxiliary counter electrode is provided in a power source or a circuit for the auxiliary counter electrode, and a current is caused to flow in the circuit for the auxiliary counter electrode according to the phase angle of a waveform generated by the power source.
It has been found that the objects of the invention are coupled.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an aluminum electrolytic surface roughening apparatus applied to the present invention, and FIG. 2 is a diagram showing a model of its current waveform.

Note that the same reference numerals are used for the same components as in the conventional example, and a brief description will be provided.

In FIG. 1, 1 is a graphite electrode placed facing the material to be treated, 2 is a graphite electrode also placed facing the material, and 3 is an auxiliary counter electrode also placed facing each other.The phase control is performed by a power source 4 described later. so that only the anode current flows. 4 is a power source, one end of which is branched and connected to the graphite electrode 1 and the auxiliary counter electrode 3; the other end is also branched and connected to the graphite electrode 2 and the auxiliary counter electrode 3. At this time, the power source 4 or the auxiliary electrode 3 has a diode-like mechanism 4 for controlling the flow of the anode current to the main counter electrode 1 or 2, although not shown. Outputs a power waveform as shown in Figure 2. In this case, QF=QtA, and the current flowing to the auxiliary counter electrode is controlled by phase angle control in both forward and reverse.

Incidentally, FIG. 2 shows each waveform at ■ to ■ shown in FIG.

By controlling the phase angle in this way and flowing current to the auxiliary counter electrode, Q' mA <Q' FA + Q□ = Q□ for graphite electrode l.
, for graphite electrode 2, Q', A<Q'+Q,, =QI
A, and melting of the graphite electrode can be prevented.

In addition, power supply 4 is QPA=QIA1 (Q0=Q'FA+Q
FP+QiA=Q'ta+Qip).

6 is an aluminum web, 7 is a guide roll that supports the aluminum web so that the clearance between the graphite electrodes 1 and 2 and the auxiliary counter electrode 3 is constant, 8 is an insulator, 9 is an electrolytic cell, and 10 is an electrolytic solution. , a pump may be used for circulation, or a heat exchanger and a filter may be installed as part of the circulation system. Regarding temperature control, it is better to install it in a circulation system and to separate and remove impurities from the electrolyte. Regarding the phase angle control of the power source 4, the third
As shown in the figure, it is generally controlled by cyrisk. That is, in Fig. 3, 11 is a rectifier circuit, 12 is a chopper circuit, 13 is a circuit that flows to the main electrode (graphite electrode 1.2 in Fig. 1), 14 is a circuit that flows to the auxiliary electrode, and 15 is the phase of the auxiliary counter electrode. This is a control circuit consisting of a silisk built in parallel to the output of the chopper circuit 12 to perform angle control.

〔Example〕

Nitric acid 10 g/12. In order to prepare an offset printing plate support of a JIS 1050 material aluminum plate in an electrolytic solution containing 2 g/l of aluminum and a temperature of 40° C., electrolytic surface roughening treatment was performed using the apparatus shown in FIG. A ferrite electrode is used as the auxiliary electrode, aluminum width 1000 mm, processing speed 1
m/min, Q, A=QIA: (300c/d
m'), QIP=QFP: (3Qc/dm
The conditions of 2) were set, and a symmetrical waveform with a power supply frequency of 40 was used. When the roughened plate was observed under an electron microscope after the smut was removed, many uniform pits of 1 μm to 5 μm were formed. In addition, during the one year of operation, there was no failure of the power supply and no wear on the graphite electrodes.

[Comparison example]

In order to create an offset printing plate support of a JIS 1050 aluminum plate in an electrolytic solution containing 10 g/l of nitric acid and 2 g/II of aluminum at a temperature of 40°C, electrolytic surface roughening treatment was performed using the apparatus shown in Fig. 4 above. Ta. A ferrite electrode was used as the auxiliary electrode, the aluminum width was 1000au, the processing speed was 1m/min, and the QFA was 31Qc/dm2. QI
A: A waveform of 290C/dm" and a power supply frequency of 40Hz was used. When the roughened plate was observed under an electron microscope after removing the smut, pits of 1 μ to 10 were found to be slightly unevenly generated. After one year of operation, it malfunctioned and stopped three times.

〔Effect of the invention〕

As is clear from the above examples, uniform pits can be generated by the electrolytic treatment method of the present invention, and complicated control of the power supply is not required, so that the number of failures is also reduced. Also, the equipment cost was about 115 yen.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram of an electrolytic surface roughening device applied to the present invention, Fig. 2 is a current waveform diagram at each point of the device shown in Fig. 1, Fig. 3 is an example of a circuit for controlling the phase angle, and Fig. 4 The figure is a schematic configuration diagram of an electrolytic surface roughening apparatus for an offset printing plate support applied to a conventional example, and FIG. 5 is a current waveform diagram in the apparatus shown in FIG. 4.・Graphite electrode, auxiliary counter electrode, power supply, diode, aluminum web, guide roll, insulator, electrolytic cell, electrolyte, rectifier circuit, chopper circuit, circuit flowing to the main counter electrode, circuit flowing to the auxiliary electrode, phase angle control circuit (main (opposite) Fig. Fig.

Claims (1)

[Claims] An electrolytic treatment method in which an alternating current is supplied between a treated material and a counter electrode in an electrolytic treatment solution to electrochemically treat the untreated material, the counter electrode being formed by a main counter electrode and an auxiliary counter electrode, A circuit for the auxiliary counter electrode is connected in parallel to the circuit connected to the main counter electrode, and a diode or a mechanism acting like a diode is provided in the power supply or the circuit for the auxiliary counter electrode to control the flow of the anode current in the main counter electrode. . An electrolytic treatment method, characterized in that a current is passed through a circuit for the auxiliary counter electrode according to a phase angle of a waveform generated by the power source.