US20150211143A1

US20150211143A1 - Aluminum plating apparatus and method for producing aluminum film using same

Info

Publication number: US20150211143A1
Application number: US14/425,457
Authority: US
Inventors: Junichi Nishimura; Akihisa Hosoe; Kazuki Okuno; Koutarou Kimura; Kengo Goto; Hideaki SAKAIDA
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2012-09-05
Filing date: 2013-06-13
Publication date: 2015-07-30
Also published as: DE112013004355T5; WO2014038263A1; CN104603332A; KR20150046013A; JP5880364B2; JP2014051687A

Abstract

The invention offers an aluminum-plating apparatus that can satisfactorily form an aluminum plating even on the surface of a base body that has a surface on which an insulating or poorly conductive metal oxide film or the like is formed. The aluminum-plating apparatus electrodeposits aluminum onto a base body by conveying the base body in a plating bath. The plating bath is divided into a first electrolysis chamber and a second electrolysis chamber by a partition plate in this order from the upstream side in the conveying direction for the base body. In the first electrolysis chamber, a negative electrode provided in the chamber is electrically connected with the base body such that the base body acts as a positive electrode. In the second electrolysis chamber, a positive electrode provided in the chamber is electrically connected with the base body such that the base body acts as a negative electrode.

Description

TECHNICAL FIELD

The present invention relates to an aluminum-plating apparatus for electroplating the surface of a base body with aluminum and a method of producing an aluminum film using the foregoing apparatus.

BACKGROUND ART

Aluminum forms a close-knit oxide film on its surface to be passivated and thus exhibits excellent corrosion resistance. For this reason, aluminum plating is performed on the surface of a steel tape and the like to enhance the corrosion resistance.
To perform aluminum plating on the surface of a steel tape, first, the steel tape is conveyed continuously into a plating bath through a conductor roll. The tape runs in a positive electrode immersed in a plating liquid in the plating bath. At this moment, the steel tape is electrically connected so as to act as a negative electrode, so that electrolysis occurs between the positive electrode and the steel tape, which is the negative electrode. As a result, aluminum is electrodeposited on the surface of the steel tape to form an aluminum plating. The steel tape running in the plating liquid undergoes a direction change by a turn roll to run upward this time. In this case, also, plating is performed in relation to the positive electrode. The steel tape on which the aluminum plating is formed leaves the plating bath, passes another conductor roll, and is taken out of the system (the published Japanese patent application Tokukaihei 05-222599 (Patent Literature 1)).
As a metallic porous body having a three-dimensional network structure, a porous body composed of aluminum holds promise as a material for increasing the capacity of the positive electrode of a lithium-ion battery. At present, exploiting conductivity, corrosion resistance, lightweight, and other excellent features of aluminum, a material produced by coating an active material such as lithium cobalt oxide on the surface of an aluminum foil is used as the positive electrode of a lithium-ion battery. When the positive electrode is formed by using the porous body composed of aluminum, it is possible to increase the surface area and to fill the active material even at the interior of the aluminum. As a result, even when the electrode is thickened, a decrease in the utilization rate of the active material is avoided. Consequently, the utilization rate of the active material per unit area is increased, and therefore the capacity of the positive electrode can be increased.
The present applicant has proposed a method of electroplating a resin formed body having a three-dimensional network structure with aluminum as a production method of the above-described aluminum porous body (the published Japanese patent application Tokukai 2012-007233 (Patent Literature 2)). The conventional aluminum molten-salt bath is required to be heated to high temperature. Consequently, when the surface of a resin formed body is electroplated with aluminum, the resin cannot withstand the high temperature and melts, which is one of the problems in this case. However, according to the method stated in Patent Literature 2, the mixing of an organochloride salt, such as 1-ethyl-3-methylimidazolium chloride (EMIC) or 1-butylpyridinium chloride (BPC), and aluminum chloride (AlCl₃) forms an aluminum bath that is a liquid at room temperature, thereby enabling a resin formed body to be electroplated with aluminum. In particular, the EMIC-AlCl₃system is good in the characteristics of the liquid, so that it is useful as an aluminum-plating liquid.
In the above-described aluminum-plated steel tape and aluminum porous body having a three-dimensional network structure, in order to obtain a surface having excellent glossiness and to increase the thickness of the layer of the aluminum plating, it is necessary that a base body having a surface of aluminum be further plated with aluminum.
However, as described above, an oxide film is formed on the surface of the aluminum. Therefore, even when it is intended to electrodeposit aluminum onto the aluminum surface, electricity cannot be supplied uniformly to the surface. As a result, a plating is formed in the shape of islands, which is a problem.

CITATION LIST

Patent Literature

Patent Literature 1: the published Japanese patent application Tokukaihei 05-222599
Patent Literature 2: the published Japanese patent application Tokukai 2012-007233

SUMMARY OF INVENTION

Technical Problem

In view of the above-described problem, an object of the present invention is to offer an aluminum-plating apparatus that can satisfactorily form an aluminum plating even on the surface of a base body that has a surface on which an insulating or poorly conductive metal oxide film or the like is formed.

Solution to Problem

The present inventors have studied intensely to solve the above-described problem and have found that it is effective to perform aluminum plating after electrolytically removing, in a plating bath, an oxide film formed on the surface of a metal. Thus, the present invention is completed. More specifically, the present invention has the constitution described below.
(1) An aluminum-plating apparatus for electrodepositing aluminum onto a base body by conveying the base body in a plating bath. The apparatus has the following feature:

- the above-described plating bath is divided into a first electrolysis chamber and a second electrolysis chamber by a partition plate in this order from the upstream side in a direction that the above-described base body is conveyed;
- in the above-described first electrolysis chamber, which is provided with a negative electrode, the negative electrode is electrically connected with the above-described base body in such a way that the above-described base body acts as a positive electrode; and
- in the above-described second electrolysis chamber, which is provided with a positive electrode, the positive electrode is electrically connected with the above-described base body in such a way that the above-described base body acts as a negative electrode.

The aluminum-plating apparatus stated in (1) above performs reverse electrolysis in the first electrolysis chamber. Therefore, even when an insulating or poorly conductive metal oxide film or the like is formed on the surface of a base body, it can be removed electrolytically, so that aluminum can be satisfactorily electrodeposited in the subsequent second electrolysis chamber.
(2) The aluminum-plating apparatus as stated in (1) above, the apparatus having, at the upstream side of an entrance of the above-described first electrolysis chamber, a first electricity supply roller that gives an electric potential to the above-described base body and concurrently conveys the base body.
The invention stated in (2) above enables the giving of an electric potential to the base body in the vicinity of the first electrolysis chamber while the base body is being conveyed.
(3) The aluminum-plating apparatus as stated in (1) or (2) above, the apparatus having, at the downstream side of an exit of the above-described second electrolysis chamber, a second electricity supply roller that gives an electric potential to the above-described base body and concurrently conveys the base body.
The invention stated in (3) above enables the giving of an electric potential to the base body in the vicinity of the second electrolysis chamber while the base body is being conveyed.
(4) The aluminum-plating apparatus as stated in any one of (1) to (3) above, in which the above-described plating bath contains a molten-salt bath composed mainly of aluminum chloride.
The invention stated in (4) above enables the use of the conventional molten-salt bath composed mainly of aluminum chloride and consequently the obtaining of a good-quality aluminum film.
(5) The aluminum-plating apparatus as stated in any one of (1) to (4) above, in which the above-described base body is a sheet formed of a resin formed body having a three-dimensional network structure that has undergone conductive treatment.
The invention stated in (5) above enables the continuous production of a resin structure that has an aluminum film on the surface of a resin formed body having a three-dimensional network structure.
(6) An aluminum-plating apparatus, having two or more aluminum-plating apparatuses each as stated in any one of (1) to (5) above;
the apparatuses being positioned in series in a direction that the above-described base body is conveyed.
The invention stated in (6) above enables the providing of only one set of incidental equipment, such as a supplying facility and a taking-up facility for the base body, so that the investment for the equipment can be reduced significantly.
(7) An aluminum-plating apparatus, having an aluminum-plating apparatus:

- that is positioned at a preceding position of the aluminum-plating apparatus as stated in any one of (1) to (6) above, the preceding position being the most upstream position in a direction that the above-described base body is conveyed;
- that electrodeposits aluminum onto the above-described base body by conveying the above-described base body in a plating bath; and
- that has a feature in that in the plating bath, which is provided with a positive electrode, the positive electrode is electrically connected with the above-described base body in such a way that the above-described base body acts as a negative electrode.

The invention stated in (7) above enables the use of the conventional aluminum-plating apparatus at the most upstream position in a direction that the base body is conveyed when the apparatus uses a base body that has a surface on which no insulating or poorly conductive metal oxide film or the like is formed. In addition, only one set of incidental equipment, such as a supplying facility and a taking-up facility for the base body, is necessary, so that the investment for the equipment can be reduced significantly.
(8) A method of producing an aluminum film, the method electrodepositing aluminum onto a base body using the aluminum-plating apparatus as stated in any one of (1) to (7) above.
The method of producing an aluminum film stated in (8) above enables the formation of a good-quality aluminum film on the surface of a base body even when the base body has a surface on which an insulating or poorly conductive metal oxide film or the like is formed.

Advantageous Effects of Invention

The present invention can offer an aluminum-plating apparatus that can satisfactorily form an aluminum plating even on the surface of a base body that has a surface on which an insulating or poorly conductive metal oxide film or the like is formed.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a diagram showing an example of the aluminum-plating apparatus of the present invention.

FIG. 2 is a diagram showing another example of the aluminum-plating apparatus of the present invention.

DESCRIPTION OF EMBODIMENTS

The aluminum-plating apparatus of the present invention is an aluminum-plating apparatus for electrodepositing aluminum onto a base body by conveying the base body in a plating bath. The apparatus has the following feature:

The above-described base body is not particularly limited. However, an outstanding effect is exerted in the case of a base body onto which the conventional aluminum-plating apparatus cannot satisfactorily electrodeposit aluminum, such as a metal having a metal oxide film (a passive film) on its surface. The types of the foregoing base body include a steel tape (a steel plate), an aluminum porous body having a three-dimensional network structure, a SUS plate, a Cu or Cu alloy plate, and a Zn or Zn alloy plate.
The above-described plating bath contains a plating liquid. The plating liquid is not particularly limited provided that the liquid has a composition capable of performing electroplating with aluminum. Aluminum has a high affinity for oxygen and has an electric potential lower than that of hydrogen. Consequently, it is difficult to perform electroplating in an aqueous solution-based plating bath, so that a molten-salt bath is used. A molten-salt bath composed mainly of aluminum chloride can be advantageously used.
As for the molten salt, an organic molten salt in the form of a eutectic salt of an organohalide and an aluminum halide and an inorganic molten salt in the form of a eutectic salt of a halogenide of an alkali metal and an aluminum halide can be used. When an organic molten-salt bath, which melts at relatively low temperature, is used, plating can be performed without decomposing a resin formed body used as a base body, which is desirable. As for the organohalide, an imidazolium salt, a pyridinium salt, and the like can be used. More specifically, 1-ethyl-3-methylimdazolium chloride (EMIC) and butylpyridinium chloride (BPC) are desirable.
When moisture or oxygen intrudes into a molten salt, the molten salt deteriorates. Therefore, it is desirable to perform plating not only in a nitrogen, argon, or other inert gas atmosphere but also in an enclosed environment.
As for the molten-salt bath, a molten-salt bath containing nitrogen is desirable. When a resin formed body having a three-dimensional network structure is used as the above-described base body, if a salt that melts at high temperature is used as the molten salt, the resin dissolves or decomposes in the molten salt more quickly than the layer of plating grows. As a result, the layer of plating cannot be formed on the surface of the resin formed body. In this case, an imidazolium salt bath can be advantageously used. An imidazolium salt bath can be used even at relatively low temperature without affecting the resin.
As the imidazolium salt, a salt containing an imidazolium cation having an alkyl group at the 1, 3 position can be advantageously used. In particular, an aluminum chloride-1-ethyl-3-methylimdazolium chloride (AlCl₃-EMIC)-based molten salt is most advantageously used because it has high stability and therefore is less likely to decompose. Plating can be performed on urethane-resin foam, melamine-resin foam, and the like. The temperature of the molten-salt bath is 10° C. to 100° C., desirably 25° C. to 45° C. As the temperature decreases to low temperature, the range of electric-current density that enables plating is narrowed, so that it becomes difficult to perform plating on the entire surface of the resin formed body. A high temperature exceeding 100° C. tends to create a problem of impairing the shape of the resin used as the base body.
When a base body having a high melting point, such as a steel tape, is used, an inorganic-salt bath can also be used as the molten salt. The inorganic-salt bath is typically a salt of a two-constituent system or multiconstituent system of AlCl₃—XCl (X: alkali metal). The foregoing inorganic-salt bath generally has a high melting temperature in comparison with an organic-salt bath such as an imidazolium salt bath but has few limitations on environmental conditions such as moisture and oxygen, thereby enabling the practical use at a low cost as a whole.
To enhance the smoothness and glossiness of a film of aluminum plating formed on the surface of a base body, an additive such as xylene, benzene, toluene, and 1,10-phenanthroline may be added. In particular, 1,10-phenanthroline can be advantageously used. It is desirable that the amount of addition of the above-described additive be 0.25 to 7 g/L. When the amount is 0.25 g/L or more, a sufficiently smooth film of aluminum plating can be obtained. When 7 g/L or less, a decrease in plating efficiency can be suppressed.
In the following, a further detailed explanation of the present invention is given by referring to the drawing as appropriate.
FIG. 1 is a diagram showing an example of the structure of the aluminum-plating apparatus of the present invention. As shown in FIG. 1, in the aluminum-plating apparatus of the present invention, a plating bath 102 containing a plating liquid is divided into a first electrolysis chamber 104 and a second electrolysis chamber 105 by a partition plate 103. A base body 101 is conveyed continuously from the first electrolysis chamber 104 to the second electrolysis chamber 105.
The partition plate 103 is provided to electrically separate the first electrolysis chamber 104 and the second electrolysis chamber 105. An insulating partition plate can be advantageously used. For example, Teflon (registered trademark), ceramics, glass, a super engineering plastic such as polyether ether ketone (PEEK), and a heat-resistant vinyl chloride resin can be used.
The partition plate 103 is provided with a passing aperture for the base body. It is desirable that the passing aperture have the minimum possible dimension only allowing the passing of the base body. For example, it is desirable that the passing aperture for the base body have the shape of a slit.
The first electrolysis chamber 104, to which the base body 101 is conveyed initially, is provided with negative electrodes 107, which are electrically connected in such a way that the base body 101 acts as a positive electrode in the first electrolysis chamber 104. This configuration creates electrolysis between the negative electrodes 107 and the base body 101. As a result, a metal oxide film formed on the surface of the base body 101 is electrolytically removed, so that the surface of the metal forming the base body 101 is exposed.
The negative electrodes 107 are not particularly limited. For example, aluminum, titanium, and copper can be advantageously used.
FIG. 1 shows, as an example, the case where two negative electrodes 107 are provided: one above the base body 101 and the other below. Nevertheless, the number of the negative electrodes 107 is not particularly limited. One electrode or three or more electrodes may be employed. The location at which the negative electrodes 107 are provided is not particularly limited. However, it is desirable to provide them at a position closest possible to the base body 101 so that the electrolysis can occur effectively.
To cause the base body 101 to act as the positive electrode in the first electrolysis chamber 104, the terminal of the positive electrode of the power source connected to the negative electrodes 107 is connected to the base body 101. In this case, to cause the electrolysis to occur effectively, it is desirable that the base body 101 be connected to the positive electrode at the upstream side in the vicinity of the entrance of the first electrolysis chamber 104.
FIG. 1 shows the case where a first electricity supply roller 106 is provided at the upstream side of the entrance of the first electrolysis chamber 104 and is connected to the positive electrode of the power source. By employing this configuration, while the base body 101 is being continuously conveyed by the first electricity supply roller 106 and a first conveying roller 110, an electric potential is given to the base body 101 by the first electricity supply roller 106, so that the base body 101 acts as the positive electrode in the first electrolysis chamber 104. FIG. 1 shows the case where the first conveying roller 110 is provided at the opposite side of the first electricity supply roller 106. Nevertheless, in place of the first conveying roller 110, an electricity supply roller connected to the positive electrode may be provided.
The quantity of the metal oxide film to be electrolytically removed in the first electrolysis chamber 104 can be adjusted as appropriate according to the quantity of the oxide film formed on the base body 101. For example, in the case where the base body is made of aluminum, the quantity of deposition or the quantity of dissolution of aluminum can be adjusted based on the following equation:
the quantity of deposition of aluminum/the quantity of dissolution of aluminum [g]=0.3352×I [A]×t [Hr] (Equation).
In the above equation, “I” denotes the current value and “t” denotes time. The constant 0.3352 is a constant specific to aluminum, and when the base body is made of another metal, the constant can be changed to the constant specific to that metal to carry out the calculation.
Subsequently, the base body 101 whose metal oxide film is removed as described above is conveyed to the second electrolysis chamber 105 through the slit formed in the partition plate 103. The second electrolysis chamber 105 is provided with positive electrodes 109, which are electrically connected in such a way that the base body 101 acts as a negative electrode in the second electrolysis chamber 105. This configuration creates electrolysis between the positive electrodes 109 and the base body 101. As a result, aluminum is electrodeposited on the surface of the base body 101.
As described above, the metal oxide film formed on the surface of the base body 101 is removed in the first electrolysis chamber 104. Consequently, a uniform aluminum plating can be formed on the surface of the base body 101 in the second electrolysis chamber 105.
The positive electrodes 109 are not particularly limited. For example, aluminum, titanium, and copper can be advantageously used.
As in the case of the negative electrodes 107, FIG. 1 shows, as an example, the case where two positive electrodes 109 are provided: one above the base body 101 and the other below. Nevertheless, the number of the positive electrodes 109 is not particularly limited. One electrode or three or more electrodes may be employed. The location at which the positive electrodes 109 are provided is not particularly limited. However, it is desirable to provide them at a position closest possible to the base body 101 so that the electrolysis can occur effectively.
To cause the base body 101 to act as the negative electrode in the second electrolysis chamber 105, the terminal of the negative electrode of the power source connected to the positive electrodes 109 is connected to the base body 101. In this case, to cause the electrolysis to occur effectively, it is desirable that the base body 101 be connected to the negative electrode at the downstream side in the vicinity of the exit of the second electrolysis chamber 105.
FIG. 1 shows the case where a second electricity supply roller 108 is provided at the downstream side of the exit of the second electrolysis chamber 105 and is connected to the negative electrode of the power source. By employing this configuration, while the base body 101 is being continuously conveyed by the second electricity supply roller 108 and a second conveying roller 111, an electric potential is given to the base body 101 by the second electricity supply roller 108, so that the base body 101 acts as the negative electrode in the second electrolysis chamber 105. FIG. 1 shows the case where the second conveying roller 111 is provided at the opposite side of the second electricity supply roller 108. Nevertheless, in place of the second conveying roller 111, an electricity supply roller connected to the negative electrode may be provided.
The quantity of the aluminum to be deposited in the second electrolysis chamber 105 can be calculated by using the above-described equation. Consequently, the current value and time can be adjusted in such a way that a desired quantity of aluminum is electrodeposited on the surface of the base body 101. The time can be adjusted by changing the conveying speed for the base body 101.
As described above, by using the aluminum-plating apparatus of the present invention, an aluminum plating can be satisfactorily formed even on the surface of a base body that has a surface on which an insulating or poorly conductive metal oxide film or the like is formed.
In the case where aluminum plating is performed on a long base body such as a steel tape and a sheet composed of a resin formed body having a three-dimensional network structure, the use of the aluminum-plating apparatus of the present invention can effectively produce a product by increasing the line speed.
In the case of the conventional aluminum-plating apparatus equipped with one plating bath, when it is intended to increase the production capacity by increasing the line speed, it can be conceived to increase the length of the positive electrode. For example, when the plating is performed vertically, the plating bath is deepened, and when the plating is performed horizontally, the plating bath is lengthened. Actually, however, the length of the positive electrode effective for the plating has a limitation. More specifically, although the plating is performed at a high current density at the position close to the conductor roll, the plating is not performed at the position far from the conductor roll. Consequently, in an apparatus equipped with one plating bath, the increase in line speed has a limitation, so that the production capacity cannot be increased.
For that reason, it can be conceived to increase the line speed by constituting the plating bath with two or more baths. However, even when two or more conventional plating apparatuses are installed in tandem to carry out continuous operation, in the case of a metal that is likely to form an oxide film on its surface, such as aluminum, the film formed in the plating bath in the preceding position cannot be satisfactorily plated with aluminum, which is a problem. More specifically, an oxide film is formed on the surface of aluminum at the space between the plating baths. When an oxide film is formed, aluminum is deposited in the form of islands. In other words, plating cannot be performed satisfactorily. Even when the space between the plating baths is filled with an N₂or other inert atmosphere, oxygen cannot be removed completely and remains at an amount on the order of ppm. Even when aluminum is exposed to such a minute amount of oxygen as described above, an oxide film (a passive film) is formed on the surface of aluminum.
To evade the above-described problem, the aluminum-plating apparatus of the present invention can remove, in the first electrolysis chamber, an oxide film formed on the surface of aluminum. Consequently, when two or more aluminum-plating apparatuses are provided in series in the conveying direction for the base body, the second and subsequent baths, also, can form a smooth and good-quality aluminum plating. By using an aluminum-plating apparatus in which two or more aluminum-plating apparatuses described above are provided in series in the conveying direction for the base body, the line speed of the base body can be increased and hence the production efficiency of the product can be increased. Because the foregoing aluminum-plating apparatus performs aluminum plating continuously using multiple aluminum-plating apparatuses, only one set of incidental equipment, such as a supplying facility and a taking-up facility for the base body, is necessary, so that the investment for the equipment can be reduced significantly.
The number of aluminum apparatuses provided in series is not particularly limited. The number can be selected as appropriate according to the purpose, such as the thickness of a layer of aluminum plating to be formed. For example, when a resin formed body having a three-dimensional network structure is used as the base body, the providing of 2 to 20 or so aluminum-plating apparatuses can effectively produce an aluminum porous body.
When a resin formed body having a three-dimensional network structure having undergone conductive treatment by coating carbon, for example, is used as the base body, a conventional aluminum-plating apparatus may be provided at a preceding positon of the above-described aluminum-plating apparatus of the present invention, the preceding positon being the most upstream position in the conveying direction for the base body. As for the conventional aluminum-plating apparatus, an aluminum-plating apparatus described below can be advantageously used. The aluminum-plating apparatus electrodeposits aluminum onto the base body by passing the base body 101 through the plating bath 202 as shown in FIG. 2 and has a feature in that in the plating bath 202, positive electrodes 209 provided in the plating bath 202 are electrically connected with the above-described base body 101 in such a way that the above-described base body 101 acts as a negative electrode.
In other words, the aluminum-plating apparatus of the present invention has an aluminum-plating apparatus:

- that is positioned at a preceding positon of the above-described aluminum-plating apparatus, the preceding positon being the most upstream position in a direction that the above-described base body is conveyed;
- that electrodeposits aluminum onto the above-described base body by conveying the above-described base body in a plating bath; and
- that has a feature in that in the plating bath, which is provided with a positive electrode, the positive electrode is electrically connected with the above-described base body in such a way that the above-described base body acts as a negative electrode.
  By performing aluminum plating by placing the above-described aluminum-plating apparatus of the present invention, which is provided with the first electrolysis chamber that performs reverse electrolysis, in series with the second or subsequent aluminum-plating apparatus in the aluminum-plating apparatuses arranged in series as described above, a uniform and good-quality aluminum plating can be formed on the base body effectively. In addition, as described above, the aluminum-plating apparatus of the present invention enables the providing of only one set of incidental equipment, such as a supplying facility and a taking-up facility for the base body, so that the investment for the equipment can be reduced significantly.

EXAMPLES

In the following, a further detailed explanation of the present invention is given based on examples. These examples are illustrative and not limit the aluminum-plating apparatus and the like of the present invention. The scope of the present invention is shown by the scope of the claims and covers all revisions and modifications included within the meaning and scope equivalent to the scope of the claims.

Example 1

Ten aluminum apparatuses of the present invention shown in FIG. 1 were placed in series to form a film of aluminum plating on a base body.

Base Body

As the base body, a resin formed body was used that had a three-dimensional network structure having a surface on which an aluminum film was formed by the sputtering process.
As the resin formed body having a three-dimensional network structure, a foamed-urethane resin formed body having a porosity of 95%, the number of pores (the number of cells) per inch of about 50, a pore diameter of about 550 μm, a width of 500 mm, and a thickness of 1 mm was used. Conductive treatment was performed by forming an aluminum film having a coating weight of 10 g/m²on the foamed-urethane resin formed body by the sputtering process.
It was confirmed that an aluminum oxide film of 30 nm was formed in the aluminum film on the surface of the resin formed body.

Aluminum-Plating Apparatus

Ten aluminum apparatuses of the present invention shown in FIG. 1 were prepared to be placed in series. The space between the aluminum-plating apparatuses was filled with nitrogen to form an inert atmosphere. The rotation speed of the roller was adjusted in such a way that the line speed of the base body to be conveyed became 0.1 to 1.0 m/min. The structure of the individual aluminum apparatus is described below.

Molten-Salt Bath

A molten-salt bath having a composition of 33-mol % EMIC and 67-mol % AlCl₃was produced by mixing them in a nitrogen atmosphere. In addition, 1,10-phenanthroline was added such that it had a concentration of 0.5 g/L.
Furthermore, nitrogen was introduced into the plating liquid to prevent the formation of an oxide film during the electrodepositing of aluminum.

Partition Plate

A partition plate made of Teflon (registered trademark) was placed in the plating bath to partition the plating bath into a first electrolysis chamber and a second electrolysis chamber. A partition plate was provided with a slit, which had a width of 560 mm and a height of 5 mm, to be used as a passing aperture for the base body.

First Electricity Supply Roller

A first electricity supply roller made of aluminum was used, the center of the roller being connected to the terminal of the positive electrode of a power source.

Negative Electrode

Negative electrodes made of aluminum were placed in the first electrolysis chamber. As shown in FIG. 1, the negative electrodes were placed at two positions: one above the base body and the other below.

First Electrolysis Chamber

To create electrolysis between the base body and the negative electrodes in the first electrolysis chamber, a current density was set at 10 A/dm².

Second Electricity Supply Roller

A second electricity supply roller made of aluminum was used, the center of the roller being connected to the terminal of the negative electrode of a power source.

Positive Electrode

Positive electrodes made of aluminum were placed in the second electrolysis chamber. As shown in FIG. 1, the positive electrodes were placed at two positions: one above the base body and the other below.

Second Electrolysis Chamber

To create electrolysis between the base body and the positive electrodes in the second electrolysis chamber, a current density was set at 5 A/dm².
The base body having undergone conductive treatment as described above was conveyed continuously into the ten aluminum apparatuses each having the above-described structure to form a film of aluminum plating on the surface of the base body. This operation formed an aluminum film of 10 μm on the surface of the base body. The formed film of plating was a uniform and good-quality film.
As described above, it was confirmed that even when the operation uses a base body that has a surface on which an aluminum oxide film is formed, the use of the aluminum-plating apparatus of the present invention can further form a good-quality film of aluminum plating.

Example 2

As shown in FIG. 2, a conventional aluminum-plating apparatus was placed at the most upstream side in the conveying direction for the base body. Nine aluminum apparatuses of the present invention used in Example 1 were placed in series at the downstream side of the above-described conventional aluminum-plating apparatus to form a film of aluminum plating on a base body.

Base Body

A resin formed body having the same three-dimensional network structure as that employed in Example 1 was used.
Conductive treatment of the resin formed body was carried out by coating a carbon paint as a conductive paint on the surface of a resinous porous body. The carbon paint contained 25% carbon particles, a resin binder, an introfier, and an antifoaming agent. The carbon black had a particle diameter of 0.5 μm.

Aluminum-Plating Apparatus

The conventional aluminum-plating apparatus placed at the most upstream side in the conveying direction for the base body had the same structure as that of the second electrolysis chamber in the aluminum-plating apparatus used in Example 1. More specifically, the plating liquid, the electricity supply roller, and the positive electrodes respectively had the same structure as that of the plating liquid, the second electricity supply roller, and the positive electrodes all used in Example 1.
The second and subsequent aluminum-plating apparatuses had the same structure as that of the aluminum-plating apparatuses used in Example 1. Nine apparatuses as described above were placed in series.
Observation of the base body having a surface on which a film of aluminum plating was formed revealed that an aluminum film of 10 μm was formed on the surface of the base body and that the formed film of plating was a uniform and good-quality film.

Comparative Example 1

A film of aluminum plating was formed on the surface of a base body through the same procedure as that used in Example 1, except that as the aluminum-plating apparatus, 10 conventional aluminum-plating apparatuses were used by placing them in series. As for the conventional aluminum-plating apparatuses, the aluminum-plating apparatus placed at the most upstream side in Example 2 were used. As with Example 1, the space between the aluminum-plating apparatuses was filled with nitrogen to form an inert atmosphere.
Observation of the film of aluminum plating formed on the surface of the base body revealed that the deposition created the shape of islands and that the film was inferior in quality to the film formed by using the apparatus of Example 1.

Comparative Example 2

A film of aluminum plating was formed on the surface of a base body through the same procedure as that used in Example 2, except that as the aluminum-plating apparatus, 10 conventional aluminum-plating apparatuses were used by placing them in series. As for the conventional aluminum-plating apparatuses, the aluminum-plating apparatus placed at the most upstream side in Example 2 were used. As with Example 2, the space between the aluminum-plating apparatuses was filled with nitrogen to form an inert atmosphere.
Observation of the film of aluminum plating formed on the surface of the base body revealed that the deposition created the shape of islands and that the film was inferior in quality to the film formed by using the apparatus of Example 2.

REFERENCE SIGNS LIST

101: Base body
102: Plating bath
103: Partition plate
104: First electrolysis chamber
105: Second electrolysis chamber
106: First electricity supply roller
107: Negative electrode
108: Second electricity supply roller
109: Positive electrode
110: Second conveying roller
111: Second conveying roller
202: Plating bath
208: Electricity supply roller
209: Positive electrode

Claims

1. An aluminum-plating apparatus for electrodepositing aluminum onto a base body by conveying the base body in a plating bath, the apparatus having a feature in that:

the plating bath is divided into a first electrolysis chamber and a second electrolysis chamber by a partition plate in this order from the upstream side in a direction that the base body is conveyed;

in the first electrolysis chamber, which is provided with a negative electrode, the negative electrode is electrically connected with the base body in such a way that the base body acts as a positive electrode; and

in the second electrolysis chamber, which is provided with a positive electrode, the positive electrode is electrically connected with the base body in such a way that the base body acts as a negative electrode.

2. The aluminum-plating apparatus as defined by claim 1, the apparatus comprising, at the upstream side of an entrance of the first electrolysis chamber, a first electricity supply roller that gives an electric potential to the base body and concurrently conveys the base body.

3. The aluminum-plating apparatus as defined by claim 1, the apparatus comprising, at the downstream side of an exit of the second electrolysis chamber, a second electricity supply roller that gives an electric potential to the base body and concurrently conveys the base body.

4. The aluminum-plating apparatus as defined by claim 1, wherein the plating bath contains a molten-salt bath composed mainly of aluminum chloride.

5. The aluminum-plating apparatus as defined by claim 1, wherein the base body is a sheet composed of a resin formed body having a three-dimensional network structure that has undergone conductive treatment.

6. An aluminum-plating apparatus, comprising two or more aluminum-plating apparatuses each as defined by claim 1;

the apparatuses being positioned in series in a direction that the base body is conveyed.

7. An aluminum-plating apparatus, comprising an aluminum-plating apparatus:

that is positioned at a preceding positon of the aluminum-plating apparatus as defined by claim 1, the preceding positon being the most upstream position in a direction that the base body is conveyed;

that electrodeposits aluminum onto the base body by conveying the base body in a plating bath; and

that has a feature in that in the plating bath, which is provided with a positive electrode, the positive electrode is electrically connected with the base body in such a way that the base body acts as a negative electrode.

8. A method of producing an aluminum film, the method electrodepositing aluminum onto a base body using the aluminum-plating apparatus as defined by claim 1.