JP2715344B2 - Electrolytic treatment of aluminum support for printing plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates, when performing electrolytic surface roughening treatment on the metal plate, it relates to an electrolytic treatment method for optimally controlling the Hare Ru printing plate aluminum support for the electrolytic reaction.

[0002]

2. Description of the Related Art An aluminum plate (including an aluminum alloy plate) is used as an aluminum support for a printing plate, particularly as a support for an offset printing plate. Generally, in order to use an aluminum plate as a support for an offset printing plate, it is necessary that the aluminum plate has appropriate adhesiveness to a photosensitive material and water retention. For this purpose, the surface of the aluminum plate must be roughened so as to have a uniform and dense grain. This surface roughening treatment has a significant effect on the printing performance and printing durability of the plate material when offset printing is actually performed after plate making, and its quality is an important factor in plate material production.

As a method for roughening the aluminum support for a printing plate, an AC electrolytic etching method is generally adopted, and a special alternating waveform current such as a normal sine wave AC current or a rectangular wave is used as a current. Have been. The surface of the aluminum plate is roughened by alternating current using a suitable electrode such as graphite as a counter electrode, and is usually performed in a single process, but the pit depth obtained there is generally shallow. And the printing durability was poor. For this reason, various methods have been proposed so as to obtain an aluminum plate suitable as a support for a printing plate having a grain having fine and even pits deeper than the diameter and having uniform pits. As a method therefor, a surface roughening method using a special electrolytic power source waveform (Japanese Patent Application Laid-Open No. 53-67507), a ratio of the quantity of electricity between the anode and the cathode during electrolytic surface roughening using an alternating current (Japanese Patent Application Laid-Open No. 54-65
607), a power supply waveform (Japanese Patent Application Laid-Open No. 55-25381), a combination of the amount of current per unit area (Japanese Patent Application Laid-Open No. 56-29699), and the like are known.

In Japanese Patent Publication No. 61-60797,
Apply an alternating waveform voltage to the aluminum plate that has a pause time such that the voltage becomes 0 in at least one of the anode time and the cathode time, so that the amount of electricity at the anode becomes larger than the amount of electricity at the cathode , A uniform rough surface can be obtained. However, when a material having a large alloy component such as JIS3003 material is used in a large amount for the aluminum plate for the printing plate, a variation in a trace component of the alloy component among the aluminum plate lots causes
In some cases, the shape of the generated grain changes, resulting in variations in printing performance. To solve this problem,
As a countermeasure against the waveform, the present inventors have recently proposed a method for manufacturing an aluminum support for a printing plate, in which the anode time per cycle is t _F and the cathode time is t _R, and the peak value of each current is reached. Are reached at t _F and t, respectively.
An electrolytic treatment method characterized in that _R is 0.1% or more and 20% or less is proposed. A number of attempts have been made to reduce the time required to reach the peak value of the current, such as reducing the inductance component in the power supply, reducing the inductance component of the load, increasing the resistance component of the load, and inserting a resistor in series with the load. Was.

[0005]

However, in order to reduce the inductance component of the power supply or the load, there are a method of reducing the capacity of the power supply and a method of reducing the size of the electrolytic treatment layer of the load. There was a problem that was not suitable. In order to increase the resistance component of the load, there is a method of inserting a resistance in series with the load. However, when the resistance increases, there is a drawback that the voltage increases and the power cost is greatly increased. Furthermore, there is a drawback that if there is a change in the load, the waveform of the current changes, and in particular, the time required to reach the peak value of the current changes, and the shape of the generated grain may change.

In addition, there has been a problem that a voltage exceeding the withstand voltage capacity is applied to the gate turn-off thyristor conventionally used for generating the alternating current, and the power supply stops. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrolytic treatment method that solves the conventional problems and provides a stable surface suitable for mass production without roughening the electric power cost, and a rough surface in which deep pits exist uniformly and densely. To provide.

[0007]

Means and Action for Solving the Problems The present inventors have
As a result of intensive studies focusing on a power supply that generates an alternating current, the present invention has been achieved. That is, the object of the present invention is to provide an aluminum support for a printing plate for performing an electrochemical treatment by supplying an alternating current between a material to be treated and a counter electrode in an electrolytic solution containing metal ions.
In the electrolytic treatment method, it puts a capacitor to the power supply circuit in parallel with the load, for printing plate and performing an alternating current originating <br/> produced thereby electrolytic graining treatment by the current inversion control circuit
This is achieved by a method for electrolytically treating an aluminum support .

In the present invention, the term “in the electrolytic treatment solution containing metal ions” means that metal ions mainly composed of a metal to be subjected to the electrolytic treatment are initially contained in the electrolytic treatment solution.
The concentration of aluminum ions contained in the electrolytic treatment of the aluminum web of the present invention is preferably 2 to 20 g / liter. This ion concentration has a great influence on the quality of the surface roughening in the case of the electrolytic surface roughening treatment.

In the present invention, a power supply containing an AC inversion control circuit for supplying an alternating current is provided with an inversion element on each of four sides of a bridge circuit, and two pairs are alternately gated with the inversion elements on opposite sides as a pair. Turning on / off by a signal means that the middle side has the role of generating an alternating current. A gate turn-off thyristor (GT)
O) is generally used. In the present invention, placing a capacitor in the power supply circuit in parallel with the load is performed by placing the capacitor in the middle of the bridge circuit. The capacity of the capacitor used is 100-100,0
00 microfarads, more preferably
0-5,000 microfarads.

Next, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a basic circuit diagram of a power supply used in the electrolytic treatment method of the present invention. In FIG. 1, 1 is a capacitor, and 2a to 2d are inversion elements. Although a gate turn-off thyristor (GTO element) having a large withstand voltage is used because of the surge voltage, the present invention is not limited to this. Inverting elements 2a, 2b, 2c, and 2d are provided on four sides of the bridge circuit, respectively, and the inverting elements 2a, 2c and inverting elements 2b, 2d on opposite sides are paired, and two pairs are alternately turned on / off by a gate signal. This generates an alternating current in the middle (counter electrode). By placing a capacitor in the middle of this bridge circuit, the time required for the currents of the anode and the cathode to reach the peak value can be remarkably reduced, and the fluctuation of the current waveform can be suppressed.

FIG. 2 is a schematic side view of one embodiment of the electrolytic processing apparatus of the present invention. In FIG. 2, reference numeral 11 denotes an aluminum web, and 12 denotes a drum roll for maintaining a clearance between an electrode and the aluminum web; Reference numeral 13 denotes a pass roll, and reference numeral 14 denotes an electrolytic solution. When roughening an aluminum web serving as a lithographic printing plate support, an electrolytic solution mainly containing nitric acid or hydrochloric acid is used as the electrolytic solution 14. 1
Reference numeral 5 denotes an outlet for the electrolytic solution, and the liquid level in the electrolytic treatment tank 20 is kept constant by maintaining the liquid level here. Reference numeral 16 denotes a main counter electrode, which is generally a graphite electrode. In order to prevent the deterioration of this electrode, a main counter electrode and an auxiliary counter electrode 2 connected in parallel are connected to the power supply.
2 (not shown) is preferably laid. Auxiliary counter electrode 2
Reference numeral 2 denotes various types such as platinum and lead, and a ferrite electrode is preferable. Reference numeral 17 denotes a pump for sending a liquid to the main counter electrode electrolytic treatment tank.
Although not shown in this embodiment, a device for measuring physical properties,
A controller for temperature control and a filter for removing foreign substances may be laid in the pipe after the pump. 18 is a power supply.

The power supply 18 includes the above-described current reversal control circuit (a bridge circuit including the reversing elements 2a, 2b, 2c and 2d) and a capacitor (details are shown in FIG. 1).
It is a power supply and supplies an alternating current to the electrolytic processing apparatus. The frequency is varied depending on the quality required, but is preferably 15 HZ or more in roughening the aluminum surface of the lithographic printing plate support. 19 is an electrolyte stock tank,
The electrolyte 14 is supplied from the electrolyte supply port 21 via the pump 17.

The electrolytic solution used in the present invention is a solution mainly composed of nitric acid or hydrochloric acid.
G / l, the concentration of aluminum ions in the electrolytic bath at that time is 2 to 20 g / l, and the concentration of hydrochloric acid in the case of hydrochloric acid is 5 to 100 g / l, and the concentration of aluminum ions at that time is preferably 2 to 30 g / l. . The current density of the electrolytic current is 10 to 80 A / d
Conditions of m ² and an electrolytic bath temperature of 30 ° C. or more are desirable for uniform graining.

Next, embodiments of the electrolytic treatment method of the present invention will be described in more detail. The aluminum support is first alkali-etched before the electrolytic treatment of the present invention.
Preferred alkaline agents are caustic soda, caustic potash, sodium metasilicate, sodium carbonate, sodium aluminate, sodium gluconate and the like. Concentration 0.01-20%, temperature 20-
90 ° C. and the time are suitably selected from the range of 5 seconds to 5 minutes, and the preferable etching amount is 0.01
５5 g / m ² .

Particularly, in the case of an aluminum support containing many impurities such as manganese, the etching amount is 0.01 to 1 g /
m ² is appropriate. Subsequently, since a substance (smut) insoluble in alkali remains on the surface of the alkali-etched aluminum plate, desmutting may be performed as necessary.

The pretreatment is as described above, but in the present invention, the surface is electrochemically roughened using an alternating waveform current in an electrolytic solution containing metal ions. The electrolytic solution containing metal ions used in the present invention is a solution mainly composed of nitric acid or hydrochloric acid. In the case of nitric acid, the concentration is 3 to 150 g / l, preferably 5 to 50 g / l, and contained therein. The concentration of the aluminum ion is 50 g / l or less, more preferably 2 to 20 g / l. The concentration in the case of hydrochloric acid is 2 to 250 g / l, more preferably 5 to 100 g / l,
The concentration of aluminum ions at that time is 50 g / l, more preferably 2 to 30 g / l. Additives such as ammonium ions may be added to the nitric acid or hydrochloric acid, but in the case of mass production, it becomes difficult to control the liquid concentration.

The current density of the electrolytic current is 5 to 100 A
/ Dm ² is appropriate, but 10 to 80 A / dm ² is more preferable. Such conditions are selected as needed depending on the quantity of electricity, the quality required, the components of the aluminum support used, and the like. The method of stabilizing the current waveform against load fluctuations by inserting an AC inversion control circuit that supplies an alternating current into the DC line developed in the present invention, inserting a capacitor in parallel with the load in the power supply circuit, and , Can be used in the production of electrolytic capacitors.

[0018]

EXAMPLE 1 Using an electrolytic treatment tank as shown in FIG. 2 and a power supply as shown in FIG. 1, a JIS1050 aluminum plate was subjected to surface roughening treatment. Nitric acid concentration 10 g / l, aluminum ion concentration in electrolyte 7 g / l, temperature 55
An electrolytic solution of ° C. was prepared and sent to the electrolytic treatment tank 20 via the pump 17. At this time, the capacity of the capacitor in the power supply 18 was 1000 μF. The amount of electricity at the anode was set to 500 coulombs, and the electrolytic surface roughening treatment was performed at a frequency of 40 HZ.

When the current waveform immediately before the electrolytic treatment tank was observed with an oscilloscope, the peak current reached 0.3 ms. When the pits after the surface roughening were observed with an electron microscope, uniform pits were formed. FIGS. 3 and 4 show an alternative to a photograph of an image obtained by observing a current waveform when the capacitance of the capacitor is changed with an oscilloscope. Example 2 Using the same electrolytic treatment tank and electrolytic solution as in (Example 1), the capacitor in the power supply was removed, and electrolysis was performed. When the power supply was turned on and the electrolysis was started, the power supply was stopped after one hour. When the cause was investigated, it was found that a voltage higher than the withstand voltage capacity of the element was applied to the gate turn-off thyristor (GTO element).

[0020]

According to the electrolytic treatment method of the present invention, the time required to reach the peak value of the current is shortened, and the electrolytic surface roughening treatment can be performed under favorable pit conditions under appropriate conditions of power cost suitable for mass production. Now you can do it.

[Brief description of the drawings]

FIG. 1 is a basic circuit diagram of a power supply used in the electrolytic processing method of the present invention.

FIG. 2 is a schematic side view of an electrolytic treatment tank according to one embodiment of the electrolytic surface roughening treatment method of the present invention.

FIG. 3 is a diagram replacing a photograph of an image on an oscilloscope of a current waveform when a 5,000 μF capacitor is used.

FIG. 4 is a diagram replacing a photograph of an image on an oscilloscope of a current waveform when a 15,000 μF capacitor is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Capacitor 2 Inverting element 2a Inverting element 2b Inverting element 2c Inverting element 2d Inverting element A Output terminal B Output terminal 11 Aluminum web 12 Electrode 13 Pass roll 14 Electrolyte 15 Electrolyte carry-out port 16 Main counter electrode 17 Pump 18 Power supply 19 Electrolyte Stock tank 20 Electrolytic treatment tank 21 Electrolyte supply port 22 Auxiliary counter electrode (not shown)

Claims (1)

(57) [Claims] 1. An electrolytic treatment method for an aluminum support for a printing plate , wherein an alternating current is supplied between an object to be treated and a counter electrode in an electrolytic solution containing metal ions to perform an electrochemical treatment. load parallel to put the capacitor, <br/> electrolytic treatment method of printing plate aluminum support and performing electrolytic graining treatment caused the Koban current by the current inversion control circuit.