JPH0514040B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for electrolytically treating a metal web.

Pass the metal web between a pair of opposing electrodes placed in the electrolyte, or add a metal web near a pair of electrodes placed opposite to one side of the metal web. The electrolytic method, also known as the so-called indirect power supply method, is a method that performs electrochemical treatment on both or one side of a metal web by passing a direct current or an alternating waveform current between these electrodes. This is a technology that has been implemented in Japan. Electrolytic methods using direct current include plating, anodic oxidation, etching, etc., and known methods using alternating current include degreasing, etching, etc. These techniques involve creating a surface with a special function imparted to one side of the metal web by electrochemical treatment, or creating surfaces with similar functions imparted to both sides of the metal web. This is done for the purpose of In particular, the advantage of the indirect power supply electrolysis method, in which a voltage is applied between a pair of electrodes facing each other to electrolyze a metal web passing through the center, is that a large current does not flow in the longitudinal direction of the metal web, so large current electrolysis This has the advantage that surfaces with desired functions can be created by high-speed electrolysis. For example, this technique is widely known in the fields of foil etching for capacitors using aluminum foil as a metal web, and electrolytic surface treatment of aluminum strips for printing plates.

Furthermore, as a method using direct current, the case of anodizing an aluminum strip is also well known. However, the problem with these techniques is that, although it depends on the method of processing the metal web, the processing voltage is generally slightly lower than that of methods in which power is supplied directly to the web using rolls or contact brushes, and can be quite high. was pointed out,
For example, in cases where direct current is used, there may be cases where the direct current power supply method has greater advantages.
In addition, in cases where alternating current is used, the indirect power feeding method described above has a very excellent advantage in cases where almost equal processing is applied to both sides of the board, but it is possible to simultaneously perform processing with slightly different functions. It was difficult to get him to do it. In general, the latter case is rare; for example, in the production technology of etched foil for capacitors using aluminum strips mentioned above, commercial alternating current with a symmetrical waveform between mutually facing electrodes is produced in hydrochloric acid. It is common to create the same etched surface on both the front and back sides by flowing the same etching surface.

As described above, the direct power supply method is selected depending on the purpose of the process, whether the current used is direct current or alternating current, and the magnitude of the current. However, Patent No. 1028098,
In the electrochemical treatment method for metal webs using asymmetrical alternating current waveforms, as described in Japanese Patent Publication No. 55-19191, a web is passed between two electrodes placed opposite each other in a liquid. Looking at the treatment on the side facing each electrode, in terms of waveform, it is subjected to reverse electrolysis, and both sides of the web are treated with the treatment described in Japanese Patent No. 1028098 and Japanese Patent Publication No. 1983-19191. It becomes impossible to carry out. Furthermore, even when electrolysis is performed by installing one or more pairs of electrodes facing one side of a metal web and applying voltage, the desired effect can be achieved because electrolysis with opposite waveforms is applied over and over again. It has become difficult to stably manufacture the coated surface. these,
In order to perform the same treatment on both sides of a metal web using the above-described method for double-sided processing of a web using an asymmetrical alternating waveform current, or to perform a desired treatment on one side of the web using the above-described method for single-sided processing, By supplying power directly through roll power supply, etc. in a location separate from the processing tank, or by supplying power in liquid using a liquid that is harmless to the target treatment, there is no need to rely on methods of separately supplying power to the metal web. I don't get it.

Generally, in these methods, the processing current flows through the metal web in the length direction of the web, so there is a constraint that a sufficient current cannot flow due to heat generation due to the voltage drop in the web. It was hot. Regarding direct power supply mechanisms such as roll power supply, an increase in the power supply current tends to cause undesirable phenomena from the viewpoint of stabilizing power supply, such as damage to the web and roll due to the generation of sparks. One important technique is how to stably increase power supply capacity. In addition, as mentioned above, when performing the same or similar processing on both sides of the metal web, especially in processing using asymmetrical current waveforms, productivity is reduced due to power supply constraints associated with direct power supply as described above. were forced to make significant sacrifices.

The present invention was made as a result of intensive research to solve the problems of the prior art, and it increases the load applied to the power supply roll in electrochemical processing of metal webs using asymmetrical alternating waveform current. The present invention relates to an electrolytic method that enables processing at a significantly higher speed than conventional methods without causing any problems.

That is, in the present invention, when electrolyzing a metal web using a power source that outputs an asymmetrical alternating waveform,
Two or more electrodes facing each other are installed on the surface of the metal web, and a power supply mechanism is provided, and an asymmetrical alternation in which the polarity is reversed most of the time is provided between each of the electrodes and the power supply mechanism. This is a method for electrolytically treating a metal web, characterized in that voltages are applied separately.

According to the present invention, it is possible to slightly change the treatment on both sides of the metal web, and it is of course possible to change both sides independently so that each side has a different function, or to make both sides the same. That is. Furthermore, even in the case of single-sided processing, it is possible to perform processing at a significantly higher speed than conventional methods.

The present invention will be described below with reference to the accompanying drawings. FIG. 1 is an example of a case in which both sides of a metal web are processed in the same way using an asymmetric waveform using the current direct feeding method.

1 is the metal web to be processed, pass roll 3,
4 and 5 select the electrolytic cell 2. Electrolytic cell 2
The electrolyte is supplied from the bottom of the electrolytic cell by a circulation system (not shown), overflows from an overflow weir provided at the top of the electrolytic cell, and is pumped back into the electrolytic cell. Continue the cycle. Inside the electrolytic cell, there are three electrodes 6, 7,
8 is installed, and the metal web connects electrodes 6 and 8,
and passed between electrodes 8 and 7. Reference numeral 9 denotes a power supply roll, which is supplied with power by pressing the metal web 1 against the pass roll 3. The three electrodes mentioned above are electrically coupled, and these three electrodes 6, 7, 8
A power supply device 10 is connected between the power supply roll 9 and the power supply roll 9 as shown in the figure, and an asymmetrical alternating waveform voltage is applied between the power supply rolls and the electrodes. When passing between the two, it will undergo electrolytic treatment. FIG. 2 schematically shows a rectangular wave voltage as an example of the asymmetrical alternating waveform voltage that is the output of the power supply device 10.
FIG. 3 schematically shows the voltage and current during electrolysis on both sides of the metal web. The electrode 6 of the metal web 1 is powered by the power supply roll 9,
If the surface on the 7 side is A and the surface on the opposite side is B, then a voltage with a waveform as shown in FIG. , 7, a current having a waveform as shown in 2 in FIG. 3 flows. On the other hand, a voltage with a waveform as shown in 3 in FIG. 3 is also applied between the B side and the electrode 8, and at this time, a current with a waveform as shown in 4 in FIG. 3 also flows from the A side to the electrode 8.

Therefore, from the power supply roll 9, the metal web 1
The current supplied to is the amount shown by the sum of 2 and 4 in FIG. 3, and it has a waveform as shown in 5 in FIG. In Figure 3, the center is zero, the top is positive, and the bottom is negative. In this way, in direct power feeding by roll feeding, if you want to perform the same treatment on both sides of a metal web, it is necessary to feed the combined amount of current flowing to each side, which makes it difficult to compare high-speed electrolysis, etc. This has become a critical failure requirement when large currents are required to be supplied. FIG. 4 shows the present invention, which has been intensively researched to solve such problems. That is, when power is supplied from the power supply roll 9 to the metal web 1, the waveforms of the power supplies 10 and 11, which are divided into at least two parts, are controlled so that the positive and negative polarities are less likely to coincide with each other. It is characterized by feeding electricity. Figure 5 shows the fourth
Regarding the case of double-sided electrolysis shown in the figure, both power supplies 10, 1
This is an example of a case where voltages having the same waveform are supplied with the phases of the voltages 1 and 1 being reversed, and were prepared to explain the present invention in detail. In other words, Fig. 4 shows that electrolysis is carried out by supplying power so that the surface of metal web 1 becomes negative with respect to counter electrodes 6 and 7 over the entire period in which the surface of metal web 1 is positive with respect to counter electrode 8. ing. That is,
Looking at the surface, a voltage waveform shown in FIG. 5 is applied between the metal web 1 and the counter electrode 8 by a power source 11. Regarding the plus/minus of the waveform, the top is positive and the bottom is negative, as in Figure 3. At this time, a current having a waveform shown by 4 in FIG. 5 flows between the surface of the metal web 1 and the counter electrode 8. On one side, a voltage waveform shown in FIG. 5 is applied between the metal web 1 and the counter electrodes 6 and 7 by a power source 10. At this time, the current flowing between the metal web 1 and the counter electrodes 6, 7 has a waveform as shown in 2 in FIG. 5, considering the same as in FIG. The current flowing to the opposite electrode through the surfaces becomes negative when the surface is positive, and after the surface changes from positive to negative, the gradual time surface remains negative and then changes to positive. Therefore, the period during which the polarities of the currents on the two surfaces match is an extremely short period from when the surface changes from positive to negative until the surface changes from negative to positive, and during this period, the current from the power supply roll 9 For the current supplied to the metal web 1, only the surface currents are added. Looking at other times in one cycle,
The polarity of the current between the surfaces is opposite, and the current supplied from the power supply roll 9 to the metal web 1 is as follows.
It is shown that this is the difference in the current value flowing between the surface and each opposing counter electrode (5 in FIG. 5).
In this way, the metal web 1 is transferred from the power supply roll 14.
In the case shown in 5 in Fig. 5, the current supplied to the
The power supply current can be reduced to about 1/3 of the case shown in . 4 and 5 show that the synchronous circuit 12 is configured such that the period in which the polarity of the output waveform of the current 10 and the output waveform of the power source 11 match has a minimum proportion to the total cycle.
However, the present invention is not limited to such a case, and also relates to an electrolysis method in which the period during which the polarities of both output waveforms match each other is minimized. Included in the present invention. Further, even when the two waveforms are different, the present invention is effective and enables electrolytic treatment to impart different functions to the front and back surfaces of the metal web while effectively reducing the power supply current.
Further, in the present invention, a side in which a power supply roll is installed as a power supply mechanism is described, but even if the power supply mechanism is replaced with liquid power supply using an electrode, the effects of the present invention will not change.

As the electrolytic solution that can be used in the present invention, conventionally known ones, that is, acidic aqueous solutions containing halogen ions or nitrate ions that have the property of attacking aluminum, can be used. Specific examples of particularly preferred oxidizing aqueous solutions include aqueous solutions containing hydrochloric acid, nitric acid, or mixtures thereof as electrolytes;
In both cases, the electrolyte concentration is approximately
0.5% to about 5% by weight, more preferably 0.8% to about 5% by weight
It is selected from a range of 3% by weight. These aqueous solutions may further contain a corrosion inhibitor (or stabilizer). For example, in the case of a hydrochloric acid electrolytic bath, chlorides such as subsalt chloride, ammonium chloride, sodium chloride, and aluminum chloride, trimethylamine, triethylamine, dimethylamine, diethylamine, methylamine, ethylamine, carbamic acid, triethanolamine, diethanolamine, monochloride, etc. Examples include amines such as ethanolamine, diamines such as ethylene diamine and hexamethylene diamine, aldehydes such as formaldehyde, acetaldehyde, and n-hexylaldehyde, and acids such as phosphoric acid, chromic acid, and nitric acid. , nitrates such as zinc nitrate, ammonium nitrate, and sodium nitrate, the above-mentioned monoamines, diamines, and aldehydes, as well as phosphoric acid, chromic acid, and sulfosalicylic acid. The amount of these corrosion inhibitors added to the electrolyte is preferably selected from the range of 0.05% to about 3% by weight.

Also, the temperature of the electrolyte is preferably between 20°C and 40°C.
The range of

Next, the effectiveness of the present invention will be explained using an example of electrolytic etching of an aluminum plate for printing plates.
First, the voltage waveform used in this experiment is an asymmetrical square wave alternating waveform as shown in Figure 2, and the fixed conditions are V _F = 24V, V _R = 14V, t _A = 6.7mSec,
t _C =10.0mSec. The electrolytic cell basically has the structure shown in FIG. 1, and the dimensions of each part are roughly as follows.

The diameter of the power supply roll 9 is 100mm, and the area of the power supply part is 20mm.
mm, and the roll material is aluminum alloy.
It is JISA1050. The pass roll 3 facing the power supply roll has a diameter of 100 mm and a surface length of 50 mm, and the roll material is hard rubber. The demension of the electrolytic cell 2 is roughly as follows. In other words, the internal dimensions of the tank are 700 mm deep, 200 mm wide, and 55 mm deep.
The diameter of the pass roll 4 at the lower center of the tank was 100 mm.
Three graphite electrodes are installed in this tank.
The graphite electrodes 6 and 7 along the side walls on both sides of the tank have a thickness of 20 mm.
mm, width is 50 mm, and the maximum length in the liquid that can face the aluminum web 1 is 500 mm. The central graphite electrode 8 has a thickness of 40 mm, a width of 50 mm, and a maximum length in the liquid facing the aluminum web 1 of 500 mm.
The width of the aluminum strip 1 is 50 mm, the thickness is 0.3 mm, and the material is A1050. The aluminum web 1 passed through approximately the center of two gaps formed by three electrodes 6, 7, and 8, and was turned by a pass roll 4 at the lower center of the tank. The electrolysis length of the aluminum web 1 was determined by controlling the overflow of the electrolyte solution level, and the length of the aluminum strip facing the graphite electrode was adjusted by adjusting the liquid level. In addition, an electrolytic solution was showered on the contact area between the power supply roll and the aluminum strip to prevent discharge and to cool the aluminum strip that was not immersed in the liquid between the power supply part and the electrolytic part.
A comparative example with the above common conditions will be described below.

Comparative example Three graphite electrodes 6, 7, 8 are electrically short-circuited,
With this, an experiment was conducted to find the limit of power supply when using the conventional technique by applying the voltage shown in FIG. 2 between the power supply roll 9 and the power supply roll 9 (FIG. 1). The load between the power supply roll and the roll facing it is 4Kg.
The aluminum web 1 was etched with caustic soda, washed, and then passed between a power supply roll 9 and a pass roll 3 and led to an electrolytic cell. The liquid level height was controlled so that the length of the aluminum strip facing the graphite electrode measured from the bottom end of the graphite electrode was 200 mm, the electrolysis area of the aluminum web 1 was approximately 4 dm ² , and the electrolysis time was 30 seconds. to 80
When the aluminum web 1 is conveyed at cm/min, the peak current that flows when aluminum becomes positive to the graphite electrode is approximately 200A, and the peak current that flows when aluminum becomes negative is approximately
It became 100A. The signal taken from the shaft inserted into the current flow path between the power supply roll and the power supply was converted to an absolute value, averaged, and converted to an average current.The current at this time was 115A, which is an extremely stable current. was observed. It was also confirmed that the good sand surface described in the example of Patent No. 1028098 was stably produced on both sides of the plate. Raise the electrolyte level further by 50 mm to make the electrolytic area of aluminum web 1 5 dm ² .
At the same time, the conveyance speed of aluminum web 1 was increased to 1m/
As a result, the average current increased to 145A, but the current sometimes fluctuated rapidly, making it impossible to provide stable power supply. Therefore, in this case, the upper limit of stable power supply is
It can be said that it is about 115A.

Embodiment A power supply was divided into two parts having equal periods and connected as shown in FIG. 4, so that the phase of the output waveform of each power supply was as shown in FIG. Examples according to the present invention will be described.

One of the two power supplies is inserted between the power supply roll 9 and the two graphite electrodes 6 and 7 that are in contact with the outer wall of the electrolytic cell, and the remaining power supply is connected between the power supply roll 9 and the central graphite electrode 8.
is connected to. The output of each power supply was monitored by converting the shaft output described in the comparative example in the same manner. When the outputs of both power supplies are each equal to 115A described in the comparative example, the length of aluminum web 1 facing the graphite electrode is 400 mm,
The conveyance speed of aluminum web is 160cm/
A value twice that of the comparative example was obtained. The power supply from the power supply roll was extremely stable, and the sand surfaces on both sides of the strip were the same as the good one described in the example of Patent No. 1028098. Furthermore, when the liquid level was raised by 100 mm and the conveyance speed of the aluminum strip was increased to 200 cm/min, the current of each power supply became 140 A using the same expression as before, and it was demonstrated that the same sand surface as before was stably generated. Ta.

As shown in the comparative examples and examples above, the method of the present invention successfully avoids the limitation of power supply by the power supply roll compared to the conventional method, and can stably perform high-speed electrolysis at least twice as fast as the conventional method. I understand.

The contents and examples of the present invention have been described above with respect to double-sided electrolytic treatment of a metal web, but the present invention is also applicable to continuous electrolytic treatment of one side of a metal web. FIG. 6 is a diagram similar to FIG. 4 in which the present invention is applied to continuous electrolytic treatment on one side, and similar effects and effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a conventional double-sided electrolytic treatment method for a metal web, FIG. 2 is a diagram of asymmetrical alternating waveforms used in the electrolytic treatment, and FIG. 3 is a diagram of voltage and current waveforms during the electrolytic treatment according to FIG. FIG. 4 is a diagram showing an example of the double-sided electrolytic treatment method for a metal web according to the present invention, and FIG. 5 is a diagram of voltage and current waveforms during the electrolytic treatment according to FIG. 4.
FIG. 6 is a diagram showing an example of the case where the present invention is applied to continuous electrolytic treatment on one side. 1... Metal web, 2... Electrolytic cell, 3, 4, 5
... Pass roll, 6, 7, 8 ... Electrode, 9 ... Power supply roll, 10, 11 ... Power supply device.

Claims (1)

[Claims] 1. When electrolyzing a metal web using a power source that outputs an asymmetrical alternating waveform, two or more electrodes are installed facing the surface of the metal web, and a power supply mechanism is further provided to connect each of the electrodes to the power supply. Between the organization and
characterized by separately applying asymmetrical alternating voltages whose polarities are reversed most of the time;
Electrolytic treatment method for metal web.