JP2011231395A - Anodic oxidation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form at a high speed an anodic oxidation film as an insulating layer on one side of a metal substrate.SOLUTION: The anodic oxidation device comprises a power supply drum 2 that supports through close contact a band-shaped material 1 made from an anodically oxidizable metal or a band-shaped material 1 having at least one surface made from a compounded conductive metal foil, which is an anodically oxidizable metal, and has a part 2a where at least the band-shaped material 1 is adhered is made from a conductive material; an opposing electrode 3 disposed facing the power supply drum 2; an electrolysis tank 5 filled with an electrolyte 4 in which the opposing electrode 3 and part of the power supply drum 2 that supports through close contact the band-shaped material 1 are immersed; a protective member 6 that is made from a nonconductive material that overlaps the end part in the width direction of the band-shaped material 1, which is closely supported by the power supply drum 2, and the part of the power supply drum 2 to which the band-shaped material 1 is not adhered, to thereby protect these parts from the electrolyte 4; and a drive unit that is synchronized with the circumferential speed of the power supply drum 2 and which forces the protective member 6 and the band-shaped material 1, which is in close contact with the power supply drum 2, to travel together in the electrolyte 4.

Description

  The present invention relates to an anodizing apparatus suitable for manufacturing a substrate for a semiconductor element and an electrode for an electrolytic capacitor that are useful for applications of a semiconductor device such as a solar cell, a thin film transistor circuit, and a display (image display device).

  Thin film solar cells using a metal substrate may be applicable to a wider range of applications than those using a glass substrate from the viewpoint of lightness and flexibility of the substrate. . Furthermore, since the metal substrate can withstand high-temperature processes, the photoelectric conversion characteristics are improved, so that high efficiency of the solar cell can be expected.

  The solar cell module improves the module efficiency by connecting the solar cells in series on the same substrate and integrating them. At this time, it is necessary to form an insulating layer on the metal substrate of the solar cell module and provide a semiconductor circuit layer for performing photoelectric conversion thereon. For example, when an iron-based material such as stainless steel is used for the substrate, it is necessary to form an insulating layer by coating Si or aluminum oxide by a vapor phase method such as CVD or a liquid phase method such as sol-gel method. However, these methods are prone to pinholes and cracks in the manufacturing process, and have an essential problem as a method for stably producing a large-area thin film insulating layer (Patent Document 1).

  On the other hand, in the case of aluminum, by forming an anodic oxide film (AAO), an insulating film having no pinholes and good adhesion can be obtained (Patent Document 2). However, AAO on aluminum is known to generate cracks when heated to 120 ° C. or higher (Non-Patent Document 1), and has a problem of increasing insulation, particularly leakage current. In addition, since aluminum softens at about 200 ° C., aluminum having a temperature higher than this temperature has extremely low strength and tends to cause permanent deformation (plastic deformation) such as creep deformation and buckling deformation. Strict restrictions are necessary. This makes it difficult to apply to outdoor solar cells.

  In order to solve the above problem, a method has been proposed in which AAO is formed as an insulating layer on a substrate made of a so-called aluminum clad material, and a compound semiconductor layer or an electrode layer which is a light absorption layer is formed thereon. In this method, the difference in coefficient of linear expansion between the metal substrate and the compound semiconductor layer can be designed to be small. Even in the formation process of the compound semiconductor layer that forms a high-temperature film at 500 ° C. or higher, cracks in the insulating layer and the compound semiconductor Does not cause problems such as peeling. In addition, since the metal base material combined with aluminum has a higher specific strength and higher temperature strength than aluminum, handling during manufacture is easy.

  AAO as an insulating layer needs not only to have a dielectric breakdown at a high voltage when used as a battery module, but also to have a small leakage current when a voltage is applied, that is, a high volume resistance. When the leak current is large, the generated current becomes a leak current between the individual batteries, and the module power generation efficiency decreases. Therefore, AAO requires a thickness of 1 μm or more, preferably 5 μm or more in order to ensure the above-mentioned performance.

  A general device for continuously anodizing strip-shaped aluminum is a structure in which a feeding roll or feeding tank is placed in the front part of the electrolytic cell and current is supplied to the aluminum. Even current flows. Anodization is electrolytic oxidation (three-electron reaction in the case of aluminum), and the thickness of AAO is proportional to the amount of electricity passed. Therefore, in the case of an apparatus that continuously anodizes strip-shaped aluminum, it is necessary to supply a current proportional to the line speed (running speed of the strip-shaped aluminum). At this time, since a proportional current also flows in the aluminum from the feeding portion to the electrolytic cell, the voltage drop increases and power loss occurs as the AAO thickness increases and the line speed increases. Furthermore, aluminum from the power feeding portion to the electrolytic cell may be melted by IR heat generation, and there is an upper limit to the AAO thickness to be generated and the line speed. Since the heat generation and the fusing limit current are determined by the resistance per unit cross-sectional area of the strip-shaped aluminum, the lower the upper limit of the AAO thickness and the line speed that can be generated, the thinner the aluminum foil.

  On the other hand, there is a demand to form a thick AAO only on one side of a strip-like thin aluminum foil, and an example is the above-described metal substrate with an insulating layer. In this case, it is possible to apply a masking film on one side and manufacture with the above-mentioned apparatus, but there is an upper limit to the AAO thickness and the line speed. Further, unlike additive films such as plating, AAO is a subtractive film, and when the electrolyte enters from the end face of the masking film, the film is easily formed. Therefore, it is necessary to select a masking film having a high adhesive strength. Furthermore, in the case of a strip-shaped metal foil joined with dissimilar metals such as clad material, a masking film is also applied to the side edges in the width direction where the dissimilar metals are exposed in order to prevent side reactions due to local cell action. Must be inactive.

  Various apparatuses for forming AAO on only one side of a strip-shaped aluminum have been proposed. A typical example is a method in which a support drum on a cross-sectional circle is placed in an anodizing tank, and an aluminum foil is brought into close contact therewith to anodize only one side of the aluminum foil (Patent Document 3). In addition, a method has been proposed in which the support drum is made conductive and power is supplied to the drum (Patent Document 4). In the latter case, since power is supplied directly from the back surface of the aluminum foil, it is possible to reduce the voltage drop and heat generation to a level that can be ignored.

  However, in this method, the electrolyte solution is easily infiltrated between the support drum and the aluminum foil. Since the AAO film is formed on the anodizing tank side and the overvoltage is high, if the electrolyte is infiltrated into the support drum, the direct current between the support drum and the counter electrode increases, and the AAO film forming current on the anodizing tank side is increased. Current loss occurs. In addition, this loss current has an electrochemical action on the contact surface of the power supply drum, and an anodized film is formed on the aluminum on the contact surface side, or the surface of the power supply drum is made of metal. As a result of anodization or anodic dissolution, the contact resistance of the contact surface increases, and local defects such as sparks may occur.

  In order to solve the above problems, Patent Document 4 proposes a device in which the material of the power supply drum is a so-called valve metal such as tantalum or niobium. In this method, an anode is formed on the surface of the valve metal along with the electrolytic operation time. An oxide film grows. Accordingly, since the contact resistance gradually increases and needs to be replaced frequently, these materials are expensive and lack practicality. On the other hand, Patent Document 5 proposes a method for preventing the electrochemical action of the contact surface by supplying water to the contact surface between the aluminum foil and the support roller. Further, Patent Document 6 describes a configuration in which both ends of an aluminum foil are covered with a non-conductive pressure-contact band with tension so that the electrolyte does not flow into the contact surface.

JP 2001-339081 A JP 2000-49372 A JP-A-4-371789 JP-A-60-210931 JP-A-6-108289 JP-A-46-39441

Takashima, et al., Tokyo Metropolitan Industrial Technology Research Institute Research Report 3 (2000) p21

  However, in Patent Document 5, not only the apparatus becomes complicated, but also the electrolyte solution is diluted by the water on the drum contact surface, so it is necessary to always manage the concentration of the electrolyte solution. In addition, when the thin layer of water on the contact surface generates gas by electrolysis, the thin layer becomes a gas film and the contact resistance increases, which may cause a spark or the like. On the other hand, in the method of covering with a tensioned band described in Patent Document 6, the band always swings with the feeding drum and the aluminum foil, and the band is easily displaced from the end of the aluminum foil, and is continuously Operation is difficult. In addition, by applying a pressure contact, wrinkles are generated in the case of a thin aluminum foil, and there is a possibility that the electrolytic solution flows from the wrinkled part.

As described above, the formation of the anodic oxide film on the contact surface side cannot be completely prevented by any method, and thus the problem that the contact resistance becomes unstable cannot be solved.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an anodizing apparatus capable of forming a film on one surface of a thin or highly resistant metal substrate at high speed.

  The anodizing apparatus of the present invention closely supports a band made of a metal that can be anodized or a band made of a composite conductive metal foil that is a metal that can be anodized at least on one side. Filled with an electrolytic solution that immerses a power supply drum made of a conductive material, a counter electrode provided to face the power supply drum, a part of the power supply drum that closely supports the belt-like material, and the counter electrode. A non-conductive material that overlaps the electrolytic cell, a short-side end portion of the belt-like material that is closely supported by the power supply drum, and a portion of the power supply drum where the belt-like material does not adhere to each other and protects from the electrolytic solution And a drive unit for causing the protective member to co-run in the electrolyte solution, and a belt-like object closely attached to the power supply drum in synchronization with a peripheral speed of the power supply drum. It is intended.

It is preferable that the power supply drum is provided with a recess in which the belt-like object runs inscribed.
It is good also as an aspect which provides the guide roller which press-contacts the said protection member to the said electric power feeding drum.
The counter electrode preferably has a large number of through holes.

  The distance between the power supply drum and the counter electrode in the portion where the strip supported by the power supply drum is in contact with the electrolyte and / or the portion where the strip is separated is at the central portion of the electrolyte immersion liquid of the strip. It is preferable that the distance between the power supply drum and the counter electrode is larger.

The protective member is preferably non-conductive rubber or a metal foil covered with non-conductive rubber.
The conductive material of the power supply drum is preferably a conductive plastic or a conductive rubber.

It is preferable that the potential of the counter electrode is negative with respect to the ground.
In particular, it is preferable that the strip is set to the same potential as the ground, and the electrolysis power source for anodization is an insulated output with respect to the ground.
It is further preferable that a monitoring unit that monitors the voltage of the power supply drum with respect to the potential of the ground is provided.
The continuous anodizing apparatus of the present invention is characterized in that a large number of the anodizing apparatuses described above are arranged in series.

  The anodizing apparatus of the present invention closely supports and supports a band made of a metal that can be anodized or a band made of a composite conductive metal foil that is a metal that can be anodized on at least one side. Electrolysis filled with an electrolyte solution that immerses a power supply drum made of a conductive material, a counter electrode provided opposite to the power supply drum, and a part of the power supply drum that closely supports the belt-like material and the counter electrode. A protective member made of a non-conductive material that overlaps the tank, the short-side end of the belt-like object that is closely supported by the power supply drum, and the portion of the power supply drum that the belt-like object does not adhere, and protects from the electrolyte solution; Since it has a belt-like object closely attached to the power supply drum in synchronism with the peripheral speed of the power supply drum and a drive unit for causing the protective member to co-run in the electrolyte, an anodic oxide film is formed on the contact surface side of the power supply drum and the belt-like object It is possible to completely prevent, the stable contact resistance can be film anodic oxide coating on one surface of the web.

  In addition, since the strip is closely supported by the power supply drum, power can be supplied directly from the back of the strip, so voltage drop and heat generation can be reduced to a negligible level, and line speed can be increased. Therefore, an anodic oxide film can be formed at a high speed even if it is a strip having a high resistance per unit width.

  Further, when the power supply drum is provided with a recess in which the belt-shaped object is inscribed, or the protection member is provided with a guide roller that press-contacts the power supply drum, the power supply drum and the short-side end of the belt-like material are fed with the power supply drum. It becomes possible to further improve the watertightness of the overlap with the portion of the drum where the strip does not adhere, and an anodized film can be formed on one side of the strip due to more stable contact resistance.

  In addition, since the continuous anodizing device of the present invention includes a large number of the above-described anodizing devices arranged in series, the surface current density at the power supply drum in each anodizing device is kept at the maximum so that no anodizing failure occurs. It is possible to manufacture at a line speed N times the number of installations, and a thick AAO of 5 μm or more for a thin strip made of aluminum having high resistance or a strip made of a composite conductive metal foil having at least one side made of aluminum. The membrane can be manufactured at high speed.

It is a schematic perspective view which shows one Embodiment of the anodizing apparatus of this invention. It is a schematic sectional drawing of the anodizing apparatus of this invention shown in FIG. It is a schematic front schematic diagram of the power supply drum provided with the recessed part which a strip | belt-shaped object carries out inscribed running. It is a schematic diagram which shows the relationship between the width | variety and diameter of an electric power feeding drum, and a strip | belt shaped object and a protection member. It is a schematic sectional drawing which shows one Embodiment of the anodizing apparatus provided with the guide roller. FIG. 6 is a schematic front view of a power supply drum provided with the guide roller of FIG. 5. It is a schematic perspective view of the anodizing device when the potential of the counter electrode is negative with respect to the ground. It is a schematic diagram of a continuous anodizing device in which a large number of anodizing devices of the present invention are arranged in series. It is the graph which showed the relationship between a running speed and AAO film forming speed.

  Hereinafter, the anodizing apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic perspective view showing an embodiment of the anodizing apparatus of the present invention, and FIG. 2 is a schematic sectional view of the anodizing apparatus of the present invention shown in FIG. As shown in FIG. 1 and FIG. 2, the anodizing apparatus 10 of the present invention is a band 1 made of a metal that can be anodized or a band 1 made of a composite conductive metal foil that is a metal that can be anodized on at least one side (hereinafter referred to as a band 1). , Which is also simply referred to as a belt 1), at least a portion 2 a where the belt 1 is in close contact with each other is provided with a power supply drum 2 made of a conductive material, and a counter electrode 3 (see FIG. In FIG. 1, the counter electrode is omitted in order to make it easy to see other portions), and a part of the power supply drum 2 that closely supports the belt 1 and the counter electrode 3 are filled with the electrolyte 4. The electrolytic cell 5, the short-side end portions (both sides) of the belt-like object 1 closely supported by the power supply drum 2, and the portion 2 b of the power supply drum 2 where the belt-shaped object 1 does not adhere (2 b is a non-conductive surface. ) And electrolyte 4 And a protective member 6 made of a non-conductive material to al protection.

  Further, an unwinding roll 21 for winding the strip 1 in a roll shape on the upstream side of the power supply drum 2, and anodization is performed on one side of the strip 1 sent to the power supply drum 2 on the downstream side. The winding roll 22 which winds up the strip | belt-shaped object 1 is provided. An unwinding roll 23 that winds the protective member 6 in a roll shape is provided between the power supply drum 2 and the unwinding roll 21, and the protective member 6 is wound between the power supply drum 2 and the take-up roll 22. Winding rolls 24 are provided on both sides of the belt 1 so that the belt 1 and the portion 2b where the belt 1 does not adhere can be overlapped by the protection member 6. Each of the take-up rolls 22 and 24 is provided with a drive unit (not shown), and the strip 1 and the protective member 6 that are in close contact with the power supply drum 2 in synchronism with the peripheral speed of the power supply drum 2 are connected to the electrolyte 4. It is possible to run together.

  In addition, the drive part provided in the winding rolls 22 and 24 drives each of the winding rolls 22 and 24 here, and the strip | belt-shaped object 1 and protection member 6 after anodizing are carried out to the winding rolls 22 and 24, respectively. Although the winding mode is described, the winding rolls 22 and 24 are simply rotatable and have a function of feeding the belt-like object 1 and the protective member 6. The structure by which the controlled winding roll is arrange | positioned may be sufficient. In the case of this configuration, a washing tank for washing the anodized belt-like material with water or a drying tank for drying after washing between the winding roll 22 and another winding roll controlled by the drive unit. May be installed.

  The power supply drum 2 itself is simply rotatable, and the power supply drum 2 is transported in a state where only one surface of the belt 1 is immersed in the electrolytic solution 4 by driving the drive unit described above. It is like that. However, the power supply drum 2 may have a drive source and rotate itself.

  Although the diameter of the power supply drum 2 depends on the production scale and the film formation speed of anodization, it can generally be selected appropriately within a range of 50 cm to 500 cm. The portion 2a of the power supply drum 2 where the strip 1 is in close contact is made of a conductive material, and the width of the conductive material does not necessarily have to be equal to the width of the strip 1; The conductive material width may be set as long as possible. The width of the conductive material is preferably 50 to 100%, more preferably 70 to 90% with respect to the strip 1.

Since the anodization generally has a surface current density of 500 mA / cm ² or less, the conductive portion of the power supply drum does not need to have a high conductivity. Further, when the conductive material of the power supply drum is a metal, the contact resistance may change with time due to the formation of an oxide film due to the mist of the electrolytic solution. Therefore, the conductive portion of the power supply drum may be made of conductive plastic or conductive rubber. It is preferable that Since these materials have a soft surface, they are also effective in preventing scratches on surfaces that are not anodized. As the conductive plastic and the conductive rubber, those made conductive by mixing carbon into a general general-purpose material can be used. These thicknesses vary depending on the desired strength and conductivity, but are preferably about 0.1 mm to 10 mm. A portion 2b of the power supply drum 2 where the strip 1 does not adhere is made of a non-conductive material. As the non-conductive material, non-conductive plastic, non-conductive rubber or the like is preferable.

The protective member is preferably non-conductive rubber or a metal foil covered with non-conductive rubber. In order to further improve water tightness, a material having adhesiveness may be applied to the side that is in close contact with the strip 1.
Depending on the diameter of the power supply drum, it is preferable to apply tension to the co-traveling protection member to ensure watertightness. In the case of a large diameter power supply drum, a non-conductive rubber belt with a steel core is more preferable. Can be used.

  The strip is made of a strip made of an anodizable metal or a composite conductive metal foil at least one surface of which is an anodizable metal. The metal that can be anodized is a strip made of aluminum, Nb, Ta, or Ti, or a composite conductive metal foil having at least one surface of these metals. These metals may be alloys. For example, in the case of aluminum, an aluminum alloy can be used in addition to pure aluminum. In general, an aluminum alloy having a purity of 90% or more is preferably used. When an anodized film is used as an insulating film, it is preferable not to include metal Si particles as a precipitate.

  Preferred examples of the metal to be combined with the anodizable metal as the composite conductive metal foil include iron, carbon steel, stainless steel, and Ti. The thickness of the strip is generally in the range of 0.02 to 0.5 mm. Even if it is a strip having a high resistance per unit width in such a unit width, the strip can be closely supported on the power supply drum, and power can be directly fed from the back of the strip, so that the anodic oxide coating can be performed at a higher speed. Can be formed.

  Examples of the electrolytic solution include sulfuric acid, phosphoric acid, chromic acid, oxalic acid, tartaric acid, malonic acid, sulfamic acid, benzenesulfonic acid, an aqueous solution of a salt thereof, or a mixture thereof. Although it is mentioned, what is necessary is just to select an optimal thing in order to obtain desired quality. The concentration and temperature of the electrolytic solution can also be appropriately selected.

  In the anodizing apparatus of the present invention, the protective member 6 overlaps both ends in the short direction of the strip 1 that is closely supported by the power supply drum 2 and the portion 2b where the strip 1 does not adhere to the power supply drum 2. Since the strip 1 and the protective member 6 that are in close contact with the power supply drum 2 in synchronism with the peripheral speed can run together in the electrolyte solution 4, it has been conventionally required when an anodized film is formed on one side. Even without using a masking film, the electrolyte solution 4 can be prevented from being soaked. In addition, since both ends of the strip 1 in the short direction are completely protected by the protective member 6, even when anodizing is performed on the strip in which a dissimilar metal such as a clad material is joined, Side reactions due to battery action do not occur. And it becomes possible to completely prevent the formation of the anodic oxide film on the contact surface side between the power supply drum and the belt-like material, and the anodic oxide film can be formed on one side of the metal substrate at a high speed by the stable contact resistance. .

  In order to further improve the watertightness of the protective member 6 that overlaps the strip 1 with the strip 1, the anodizing device of the present invention is designed to suppress meandering of the protective member 6 that overlaps the strip 1. It is good also as an aspect which makes the diameter of the electric power feeding drum 2 of the driving | running | working part of the protection member 6 small. This will be described with reference to FIGS. FIG. 3 is a schematic front view of the power supply drum provided with recesses in which the belt-like object and the protection member run inscribed on the power supply drum. FIG. 4 is a diagram for explaining the width and diameter of the power supply drum and the relationship between the belt-like object and the protection member. FIG. 3 and 4, the same reference numerals are given to the same components as those in FIGS. 1 and 2, and description thereof will be omitted unless otherwise necessary (hereinafter, in other drawings). The same).

As shown in FIGS. 3 and 4, the power supply drum 2 is provided with a recess (notch portion) in which the strip 1 travels inward and a recess in which the protection member 6 travels inward. In FIG. 4, W ₃ and D ₃ are the entire width and drum diameter of the power supply drum 2, W ₂ and D ₂ are the outer width and drum diameter of the protective member 6 contacting the power supply drum 2, and W ₁ and D ₁ are The width of the strip 1 and the drum diameter are indicated, and W ₀ indicates the width of the conductive material portion of the power supply drum. By setting the relationship of the drum diameters to D ₃ > D ₂ > D ₁ , the meandering of the protective member 6 that overlaps the belt-like object 1 is suppressed by the recesses provided in the power supply drum 2, and the relationship between the drum widths described above. When W ₃ > W ₂ > W ₁ > W ₀ , the band 1 is overlapped with the protective member 6 with good water tightness, and the penetration of the electrolyte into the back surface of the band 1 is more effective. Can be prevented. Here, the power supply drum 2 is shown with a recess in which the strip 1 is inscribed and a recess in which the protective member 6 is inscribed, but only the recess in which the strip 1 is inscribed is shown. It is good also as an aspect which provides.

  The anodizing apparatus of the present invention may be configured such that a guide roller that presses the protective member 6 against the power supply drum 2 is provided. This will be described with reference to FIGS. FIG. 5 is a schematic cross-sectional view showing an embodiment of an anodizing apparatus provided with a guide roller, and FIG. 6 is a schematic front view of a power supply drum provided with the guide roller of FIG. As shown in FIGS. 5 and 6, in this anodizing apparatus, a protective member 6 that overlaps both ends of the strip 1 in the short direction and a portion 2 b where the strip 1 does not adhere is pressed against the power supply drum 2. Guide rollers 7 are provided at four locations. The surface of the guide roller 7 is insulated. By providing such a guide roller 7, the strip 1 is overlapped with better water tightness by the protective member 6, and the intrusion of the electrolyte into the back surface (the surface in close contact with the power supply drum) of the strip 1. Can be blocked.

  In addition, although the aspect which provided the guide roller 7 only in the part immersed in the electrolyte solution 4 of the power supply drum 2 here is shown, the guide roller 7 is the part which is not immersed in the electrolyte solution 4 of the power supply drum 2 It is good also as an aspect provided. For example, even if the guide roller 7 is provided only in a portion (between the unwinding and winding roll 23 of the protective member 6 and the electrolytic solution 4) that is not immersed in the electrolytic solution 3 of the power supply drum 2, the meandering of the protective member 6 is performed. Therefore, it is possible to overlap the belt-like object 1 and the portion 2b where the belt-like object 1 does not adhere with good water tightness.

  In the anodic oxidation, a large amount of hydrogen gas is generated from the counter electrode during the reaction, and reaches the anodized surface of the strip by buoyancy. If a film is formed on the anodized surface, defective anodic oxidation will occur. Therefore, it is necessary to stir the electrolyte in the electrolytic cell. To increase the efficiency of this stirring, the counter electrode must have a large number of through-holes. Is preferred. The shape of the through-hole varies depending on the type of stirring of the electrolyte (for small devices, a stirrer (stirrer) is selected, or for large devices, a flow is generated in the electrolyte to stir) However, it can be appropriately selected from circular, square, slit, mesh, and the like. The individual opening size varies depending on the distance between the power supply drum and the counter electrode, but is not preferable from the viewpoint of applying a uniform electric field to the anodized surface. For example, the distance between the power supply drum and the counter electrode is not preferable. Is 10 cm, the diameter is preferably 2 cm or less with a circular opening. A common electrode such as carbon or aluminum can be used as the counter electrode.

  As the power supply waveform at the time of anodization, a direct current is generally used, but an optimal waveform such as an alternating current waveform in which direct current is superimposed can be selected. The current density during anodization can be freely selected. For example, it may be a constant value during the processing time, or the current density may be gradually increased. The electrolytic method at the time of anodization may be a constant current method or a constant voltage method.

  In the anodic oxidation, an oxide film is formed by setting a positive potential to the counter electrode, and it is preferable to apply a negative voltage to the ground as the potential of the counter electrode. As a result, the potential of the strip can be made close to the ground potential, and the entire facility for handling the strip by roll-to-roll can be set to the ground potential. In the opposite case, it is necessary to make the entire facility have a potential with respect to the ground, which is not only dangerous, but also an abnormal discharge such as a spark between the strip and the facility, which may cause a product defect.

  In particular, it is more preferable that the strip is made to coincide with the ground potential, and both the positive electrode and the negative electrode output of the electrolysis power supply have an insulating output with respect to the ground. Thereby, the abnormal discharge of a strip | belt-shaped object and an installation can be prevented completely in roll-to-roll parts other than an electrolytic cell. This is schematically shown in FIG. In order to make the strip 1 coincide with the ground potential, it is possible to place at least one conductive roll 30 in a roll-to-roll portion other than the electrolytic cell 5 and electrically connect the roll to the ground.

  Furthermore, when the electrolysis method (the method in which a current flows between the power supply drum and the counter electrode) is a constant current method or a constant voltage method, it is preferable to monitor the voltage of the power supply drum with respect to the ground potential. As a result, the watertightness of the protective member described above is temporarily reduced to cause a leakage current, or the contact resistance between the belt and the feeding drum is changed in the longitudinal direction of the anodized film on the belt. Quality fluctuation factors can be monitored.

  The counter electrode 3 is preferably provided at substantially equal intervals on the entire surface facing the strip 1 that is in close contact with the power supply drum 2 immersed in the electrolytic solution 4, and the shape thereof is a curved plate concentric with the power supply drum 2. The shape is preferred. However, when the counter electrode 3 is located in the electrolytic solution 4 at a completely equal interval on the power supply drum 2, the portion of the anodized strip that comes into contact with the electrolytic solution 4 and the portion that separates from the electrolytic solution 4 are used. It is preferable to make the effective electric field small because current concentration due to electric field concentration causes anodic oxidation failure. In order to reduce the effective electric field in this way, it is easy to use the electrolytic solution resistance, an arrangement that increases the distance between the power supply drum and the counter electrode in the liquid contact portion and / or the liquid separation portion, An arrangement in which the counter electrode is not provided in the liquid contact portion and / or the liquid separation portion, or an arrangement using them in combination can be employed.

FIG. 2 shows a counter electrode arrangement in which the distance between the power supply drum 2 and the counter electrode 3 is increased in the liquid contact portion and the liquid separation portion. In other words, the interval P ₁ between the power supply drum 2 and the counter electrode 3 in the portion where the strip 1 supported by the power supply drum 2 is in contact with the electrolytic solution 4 and the power supply drum in the portion where the strip 1 is separated from the electrolytic solution 4. the interval P ₂ between the 2 and the counter electrode 3 is made larger than the distance P ₃ between the power supply drum 2 and the counter electrode 3 in the central part that immersion in the electrolyte solution 4 of the web 1. Here, the intervals P _{1 to} P ₃ are the shortest distances connecting the power supply drum and the counter electrode. By adopting such a counter electrode arrangement, the effective electric field can be reduced, and the occurrence of defective anodic oxidation can be suppressed. The arrangement in which the counter electrode is not provided in the liquid contact portion and the liquid separation portion is as shown in FIG.

In the previous stage of the anodizing treatment, the strip is usually subjected to a washing treatment. This cleaning treatment is for removing dirt on the aluminum surface, and a known method such as immersing in an alkaline solution having the effect of removing dirt while dissolving the natural oxide film is used. Moreover, you may perform a roughening process as needed. This roughening treatment is for improving the adhesion with the layer provided on the surface of the anodic oxide coating by providing irregularities on the surface, mechanical roughening method, chemical roughening method, It is carried out by an electrochemical roughening method or a known method combining them. Also in the anodizing apparatus of the present invention, a pretreatment tank for performing such pretreatment and a water washing tank for washing and removing the pretreatment liquid may be provided upstream of the unwinding roll 21.
On the other hand, the band-like material on which the AAO film after the anodic oxidation treatment is formed is usually subjected to a drying treatment after passing through a washing layer for washing and removing the electrolytic solution.

  Next, the operation of the anodizing apparatus of the present invention will be described with reference to FIG. 1 and FIG. First, the belt-like object 1 wound in a roll shape is fed out from the unwinding roll 21, closely supported by the power supply drum, and then wound around the winding roll 22. Similarly, the protective member 6 wound in a roll shape is fed from the unwinding roll 23 and wound around the winding roll 24. At this time, an electrolysis of the end in the short direction of the strip 1 that is tightly supported by the power supply drum 2 and the portion 2b of the power supply drum 2 where the strip 1 is not in close contact with the back surface of the strip 1 by the protective member 6 is performed. It is made to overlap so that the penetration | invasion of a liquid can be blocked | prevented. In this state, a part of the power supply drum 2, for example, the center of the drum is immersed in the electrolytic solution 4 in the electrolytic cell 5. Here, the drive unit is driven, and the belt 1 and the protective member 6 closely adhered to the power supply drum 2 in synchronism with the peripheral speed of the power supply drum 2 are allowed to co-run in the electrolyte 4 and the anodizing device 1 is turned on. When a current flows between the power supply drum 2 and the counter electrode 3, an anodic oxide film is formed on one surface of the strip 1 that is not in close contact with the power supply drum 2.

  The continuous anodizing apparatus shown in FIG. 8 has a configuration in which three anodizing apparatuses 10a, 10b, and 10c are arranged in series, and the strip 1 is fed from the unwinding roll 21 to be anodized apparatus 10a, 10b. 10c, and is wound around the take-up roll 22 via the rolls 25a, 26a, 25b, 26b, 25c and 26c, and the protective member 6 is fed from the unwind roll 23 to the anode. It is configured to be wound around the winding roll 24 via the feed rolls 27a, 28a, 27b, 28b, 27c and 28c between the oxidizers 10a, 10b and 10c.

  Between the unwinding roll 21 and the feeding roll 25a, a pretreatment layer 11 for preprocessing the band 1 is provided. Between the feeding roll 26c and the winding roll 22, an anodized band is provided. A washing tank 12 for washing water and a drying tank 13 for drying after washing are installed. In addition, in the continuous anodizing apparatus shown in FIG. 8, although the protection member 6 is collectively shown in series of three anodizing apparatuses 10a, 10b, and 10c, each anodizing apparatus 10a, 10b, and 10c is shown. It is good also as an aspect which provides the unwinding roll 23 and the winding roll 24 in each of each.

Although the anodic oxidation of aluminum depends on the electrolytic solution and electrolysis conditions, the Coulomb efficiency of electrolytic oxidation is about 3 C / (cm ² · μm), and about 2 μm / min per energizing current with a surface current density of 100 mA / cm ² . It becomes the film forming speed. At this time, assuming that the surface current density is D1 (mA / cm ² ), the electrolysis time is T (min), and the required AAO film thickness is H (μm), T = 50 × H / D1 (min). . If the film forming speed is S, S = 0.02 × D1, and T = H / S. Assuming that the electrolyte immersion length of the strip is L (m) and the running speed of the strip is LS (m / min), LS = L / T = 0.02 × L × D1 / H = L × S / H Yes, the traveling speed LS is proportional to L and D1 or S, and inversely proportional to H.

  FIG. 9 is a graph showing the relationship between the running speed and the AAO film forming speed when the AAO thickness H is 10 μm. (A), (b), and (c) in the figure are cases where the electrolytic cell length L is 5, 10, and 15 m, respectively. The traveling speed LS can be increased in proportion to the AAO film forming speed S. In the case of the present invention, the electrolytic cell length L is the distance at which the power supply drum is immersed in the electrolytic solution. For example, in the case where the diameter of the power supply drum is about 3 m, the electrolytic cell length can be set to 5 m when immersed slightly larger than the center of the drum. Since the AAO film is formed only on one side and the other side remains a metal, it can be subsequently anodized by the same drum power feeding. Therefore, if N electrolytic cells are arranged in series, the traveling speed can be increased N times. FIGS. 9B and 9C illustrate the traveling speed when two and three electrolytic cells are arranged in series, respectively. The vertical axis on the right side of FIG. 9 is the electrolytic current flowing in the traveling direction per 1 cm width of the strip in the all-immersion type electrolysis apparatus described later. In the present invention, this current does not flow as described above. Power is supplied directly from the back of the belt.

In the conventional electrolyzer that immerses the entire strip, it is necessary to pass an electrolytic current in the running direction of the strip from the feeding portion to the electrolytic cell as described above. At this time, when the electrolytic current flowing in the running direction per 1 cm width of the strip is D2 (A / cm), it is necessary to grow AAO of the necessary thickness on the strip area immersed in the electrolytic cell per unit time. From the traveling speed LS (m / min), the AAO thickness H (μm), and the Coulomb efficiency 3 C / (cm ² · μm), D2 = LS × H × [Coulomb efficiency] × 100/60 = 5 × LS × H. Therefore, D2 is a current proportional to the traveling speed and the AAO thickness regardless of the AAO film forming speed and the electrolytic cell length. Since the value shown on the right vertical axis in FIG. 9 is the case where the AAO thickness is 10 μm, D2 = 50 × LS with respect to the left vertical axis LS.

  On the other hand, there is an upper limit to the current that flows from the feeding portion of the strip to the electrolytic cell. When the aluminum foil is 100 μm, even if it is sufficiently cooled by a water-cooled shower or the like, if it exceeds 150 A / cm, it is heated due to IR heat generation due to the resistance of aluminum. Runaway and increased risk of fusing. Therefore, regardless of the film forming speed and electrolytic cell length in FIG. 9, the electrolysis current in the width direction needs to be 150 A / cm or less, that is, the traveling speed is 3 m / min or less. Since the IR heat generation and fusing limit current of the strip are determined by the resistance per unit cross-sectional area, the limit current per 1 cm width becomes smaller as the aluminum foil becomes thinner. Further, in a clad material in which a high-strength but high-resistance metal such as steel, stainless steel, and Ti is combined with thin aluminum, the limit current is similarly reduced, and the traveling speed needs to be reduced.

  In principle, it is also possible to improve the line speed by installing in series in multiple stages in the conventional electrolyzer that immerses the entire strip. However, in the case of single-sided AAO film formation, a masking film affixing step and a peeling step are added to supply power to each electrolysis device, which is not realistic. Moreover, in the electrolyzing apparatus of the whole immersion method, when the power feeding method is indirect power feeding, a power feeding tank is provided and a voltage having a polarity opposite to that of anodization is applied. Therefore, when indirect power feeding is performed by installing multiple stages of electrolytic cells, a reverse voltage is applied to the AAO film formed by the preceding apparatus during the power feeding process, and abnormalities such as peeling of the AAO film occur. When AAO is formed on both sides of a strip, a masking film is not necessary. However, since the AAO film is insulative, if an AAO film is formed on both sides, multistage power feeding is not possible in the first place. However, as described above, the electrolytic current flowing in the traveling direction requires a current twice that of the single-side film formation, and it is more difficult to increase the traveling speed. Therefore, this continuous anodizing apparatus is an extremely effective apparatus configuration when a thick AAO film having a thickness of 1 μm or more is manufactured on one side of a thin aluminum foil or cladding material having high resistance.

DESCRIPTION OF SYMBOLS 1 Band-shaped object 2 Feeding drum 2a Band-shaped object contact | adhering part 3 Counter electrode 4 Electrolytic solution 5 Electrolytic tank 6 Protection member 7 Guide roller 10 Anodizing device

Claims (11)

A power supply comprising a band made of an anodizable metal or a band made of a composite conductive metal foil which is an anodizable metal on at least one side, and at least a portion where the band is in close contact is made of a conductive material. Drums,
A counter electrode provided to face the power supply drum;
An electrolytic cell filled with an electrolytic solution for immersing a part of the power supply drum that closely supports the belt-like object and the counter electrode;
A protective member made of a non-conductive material that overlaps a short-side end portion of a belt-like object that is closely supported by the power supply drum and a portion of the power supply drum that the belt-like object does not adhere to protect from the electrolytic solution. When,
A drive unit for causing the belt-like object closely attached to the power supply drum in synchronization with the peripheral speed of the power supply drum and the protection member to co-run in the electrolyte;
An anodic oxidation apparatus characterized by comprising:   The anodizing apparatus according to claim 1, wherein the power supply drum is provided with a recess in which the belt-like object runs inscribed.   The anodizing apparatus according to claim 1, wherein a guide roller that presses the protective member against the power supply drum is provided.   4. The anodizing device according to claim 1, wherein the counter electrode has a plurality of through holes.   The distance between the power supply drum and the counter electrode in the portion where the strip supported by the power supply drum is in contact with the electrolyte and / or the portion where the strip is separated is at the central portion of the electrolyte immersion liquid of the strip. The anodizing device according to claim 1, wherein the anodizing device is larger than an interval between the power supply drum and the counter electrode.   The anodizing apparatus according to claim 1, wherein the protective member is a non-conductive rubber or a metal foil covered with a non-conductive rubber.   The anodizing apparatus according to claim 1, wherein the conductive material of the power supply drum is a conductive plastic or a conductive rubber.   The anodizing apparatus according to claim 1, wherein the potential of the counter electrode is negative with respect to the ground.   The anodizing apparatus according to claim 1, wherein the strip has the same potential as the ground, and the power source for electrolysis has an insulated output with respect to the ground.   The anodizing apparatus according to claim 8, further comprising a monitoring unit that monitors a voltage of the power supply drum with respect to the ground potential.   A continuous anodizing device in which a large number of anodizing devices according to any one of claims 1 to 10 are arranged in series.

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