JP6331808B2 - Method for producing porous aluminum body - Google Patents

Description

  The present invention relates to a method for producing a porous aluminum body having a three-dimensional network structure.

  Metal porous bodies having a three-dimensional network structure are used in various fields such as various filters, catalyst carriers, and battery electrodes. For example, Celmet (manufactured by Sumitomo Electric Industries, Ltd .: registered trademark) made of a porous nickel body having a three-dimensional network structure (hereinafter referred to as “nickel porous body”) is an electrode material for batteries such as nickel metal hydride batteries and nickel cadmium batteries. It is used as Celmet is a metal porous body having continuous air holes, and has a feature of high porosity (90% or more) compared to other porous bodies such as a metal nonwoven fabric.

  Such a nickel porous body is obtained by forming a nickel layer on the surface of a porous resin skeleton having continuous vents such as foamed urethane, then heat-treating it to decompose the foamed resin molded body, and further reducing the nickel. It is done. The formation of the nickel layer is performed by depositing nickel by electroplating after applying carbon powder or the like to the surface of the skeleton of the foamed resin molded body and conducting a conductive treatment.

In addition to nickel, aluminum also has excellent characteristics such as conductivity, corrosion resistance, and light weight. In battery applications, for example, a positive electrode of a lithium ion battery is coated with an active material such as lithium cobalt oxide on the surface of an aluminum foil. Is used.
In order to improve the capacity of the positive electrode using aluminum, an aluminum porous body having a three-dimensional network structure with a large aluminum surface area (hereinafter referred to as “aluminum porous body”) is used. It is also conceivable to fill the active material. This is because by using the porous aluminum body, the active material can be retained even when the electrode is thickened, and the active material utilization rate per unit area is improved.

As a method for producing a porous aluminum body, Japanese Patent No. 3413666 (Patent Document 1) discloses that a two-dimensional net-like plastic substrate having an internal communication space is subjected to an aluminum vapor deposition process by an arc ion plating method to be 2 to 20 μm. A method for forming a metallic aluminum layer is described.
According to this method, it is said that an aluminum porous body having a thickness of 2 to 20 μm can be obtained, but it is difficult to manufacture in a large area because of the vapor phase method, and depending on the thickness and porosity of the substrate, It is difficult to form a uniform layer. In addition, there are problems such as a slow formation rate of the aluminum layer and an increase in manufacturing cost due to expensive equipment. Further, when a thick film is formed, there is a risk that the film may crack or aluminum may fall off.

Japanese Patent Application Laid-Open No. 08-170126 (Patent Document 2) discloses a film made of a metal (such as copper) that forms a eutectic alloy below the melting point of aluminum on the skeleton of a foamed resin molding having a three-dimensional network structure. After forming, an aluminum paste is applied, and heat treatment is performed at a temperature of 550 ° C. or higher and 750 ° C. or lower in a non-oxidizing atmosphere to eliminate the organic component (foamed resin) and to sinter the aluminum powder. Is described.
However, according to this method, a layer that forms a eutectic alloy with aluminum is formed, and a high-purity aluminum layer cannot be formed.

  As another method, there is a method of performing aluminum plating on a foamed resin molded body having a three-dimensional network structure. JP 2012-007233 A (Patent Document 3) discloses a porous aluminum body obtained by this plating method. The invention is described for a capacitor using as an electrode. According to the method described in Patent Document 3, it is possible to uniformly plate high-purity aluminum on a porous resin molded body having a three-dimensional network structure, and to produce a high-quality aluminum porous body Can do.

  By the way, an electrochemical device using a non-aqueous electrolyte such as the above-described lithium ion battery or capacitor needs to be manufactured in an environment in which moisture is sufficiently removed, and a current collector used as an electrode needs to be sufficiently dried. There is. Since the porous aluminum body used in the capacitor described in Patent Document 3 adsorbs a relatively large amount of moisture on the surface of the skeleton, it is sufficiently dried to be used as an electrode for an electrochemical device as described above. It is necessary to perform a process.

Japanese Patent No. 3413662 JP 08-170126 A JP 2012-007233 A

  In view of the above problems, an object of the present invention is to provide a method for producing a porous aluminum body having a three-dimensional network structure with a small amount of moisture adsorption.

The method for producing a porous aluminum body according to an aspect of the present invention includes:
A step of producing a conductive resin molding by conducting a conductive treatment by applying a carbon paint on the surface of a resin molding having a three-dimensional network structure; and
Producing a dried conductive resin molded body by setting the moisture adsorption amount of the conductive resin molded body to 100 mg / m ² or less per 1 mm thickness per apparent unit area of the conductive resin molded body;
Forming an aluminum film on the surface of the dried conductive resin molding by molten salt electroplating;
Removing the substrate;
It is a manufacturing method of the aluminum porous body which has this.

  According to the said invention, it becomes possible to provide the manufacturing method of the aluminum porous body which has a three-dimensional network structure with little moisture adsorption amount.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.
(1) An aluminum plating solution according to an aspect of the present invention is a process for producing a conductive resin molded body by conducting a conductive treatment by applying a carbon paint on the surface of a resin molded body having a three-dimensional network structure. A step of producing a dry conductive resin molded body by setting the moisture adsorption amount of the conductive resin molded body to 100 mg / m ² or less, and forming an aluminum film on the surface of the dry conductive resin molded body by molten salt electroplating And a method for producing a porous aluminum body, comprising: a step of removing the substrate.
As in the invention described in (1) above, by using a dry conductive resin molded product having a moisture adsorption amount of 100 mg / m ² or less as a base material before forming an aluminum film, an aluminum porous body having a small moisture adsorption amount is used. The body can be manufactured.

(2) The method for producing a porous aluminum body according to the above (1) is characterized in that, in the step of producing the dried conductive resin molded body, the conductive resin molded body is subjected to a heat treatment to heat the conductive resin molded body. The adsorption amount is preferably 100 mg / m ² or less.
As in the invention described in (2) above, the moisture adsorption amount of the conductive resin molded body can be efficiently reduced by heat-treating the conductive resin molded body.

(3) In the method for producing a porous aluminum body according to (1) or (2) above, the conductive resin molded body has a basis weight of a conductive layer of 1 g / m ² or more and 20 g / m ² or less. Is preferred.
As in the invention described in (3) above, the amount of moisture contained in the conductive resin molded body can be reduced by relatively reducing the basis weight of the conductive layer in the conductive resin molded body.

(4) As for the manufacturing method of the aluminum porous body as described in any one of said (1)-(3), it is preferable that the said carbon coating material contains carboxymethylcellulose as a binder.
Since the carbon paint using carboxymethyl cellulose as a binder can make the conductive layer on the surface of the skeleton of the resin molded body dense, the amount of water contained in the conductive resin molded body can be reduced.

[Details of the embodiment of the present invention]
The specific example of the manufacturing method of the aluminum porous body which concerns on embodiment of this invention is demonstrated in detail below. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included.

<Method for producing porous aluminum>
The present inventors examined how the porous aluminum body having a three-dimensional network structure adsorbs moisture. As a result, the porous aluminum body obtained by the conventional manufacturing method is a hollow part of the skeleton. It has been found that the surface has a microporous layer (hereinafter referred to as microporous layer), and this microporous layer adsorbs moisture. Therefore, the present inventors examined reducing the amount of moisture adsorbed by the aluminum porous body by reducing the thickness of the microporous layer formed inside the skeleton of the aluminum porous body. As a result, it is possible to thin the microporous layer formed on the inner side of the skeleton by using a dry conductive resin molded body having a moisture adsorption amount of 100 mg / m ² or less as a base material before forming the aluminum film. I found out that I can do it.

  This mechanism is considered as follows. That is, when aluminum plating is performed in a state where the conductive layer on the surface of the resin molded body contains a large amount of water, the adsorbed water reacts with the plating solution to produce aluminum hydroxide, which is γ-alumina during the heat treatment described later. It is thought that a microporous layer is formed by changing to. For this reason, it is considered that the generation of aluminum oxide can be suppressed by sufficiently removing moisture from the conductive layer, and the thickness of the microporous layer formed inside the skeleton of the aluminum porous body can be reduced. .

From the above, the method for producing an aluminum porous body according to an embodiment of the present invention includes a step of producing a dry conductive resin molded body by setting the moisture adsorption amount of the conductive resin molded body to 100 mg / m ² or less. doing.
Hereinafter, each process in the manufacturing method of the aluminum porous body concerning the embodiment of the present invention is explained in detail.

(Process for producing a conductive resin molding)
First, a resin molded body having a three-dimensional network structure and communication holes is prepared. Any resin can be selected as the material of the resin molded body. Examples of the material include foamed resin moldings such as polyurethane, melamine, polypropylene, and polyethylene.
Foamed urethane and foamed melamine can be preferably used as a foamed resin molded article because they have high porosity, have pore connectivity and are excellent in thermal decomposability. Urethane foam is preferable in terms of uniformity of pores, availability, and the like, and in addition, a product having a small pore diameter can be obtained.

  Resin moldings often have residues such as foaming agents and unreacted monomers in the foam production process, and it is preferable to perform a cleaning treatment for the subsequent steps. The resin molded body forms a three-dimensional network as a skeleton, thereby forming continuous pores as a whole. The urethane skeleton has a substantially triangular shape in a cross section perpendicular to the extending direction.

The foamed resin molded body preferably has a porosity of 80% to 98% and a pore diameter of 1 μm to 3500 μm. In addition, the hole diameter in the case of a foamed resin molding shall mean a cell diameter.
The porosity is defined by the following equation.
Porosity = (1− (weight of porous material [g] / (volume of porous material [cm ³ ] × material density))) × 100 [%]
In addition, the pore diameter is an average value obtained by enlarging the surface of the resin molded body with a microphotograph and the like, counting the number of pores per inch (25.4 mm) as the number of cells, and calculating the average pore diameter = 25.4 mm / cell number. Ask for.

In order to electroplat aluminum on the surface of the resin molded body, the surface of the resin molded body needs to be electrically conductive in advance. The conductive treatment can be performed by applying and drying a carbon paint containing conductive carbon particles.
The suspension as the carbon paint preferably contains carbon particles, a binder (binder), a dispersant and a dispersion medium. In order to uniformly apply the carbon particles, the suspension needs to maintain a uniform suspension state. For this reason, it is preferable that the suspension is maintained at 20 ° C to 40 ° C. When the temperature of the suspension is 20 ° C. or higher, a uniform suspended state can be maintained, and a good carbon particle layer can be formed on the surface of the skeleton forming the network structure of the porous resin body. Moreover, it can suppress that the evaporation amount of a dispersing agent increases because the temperature of a suspension liquid is 40 degrees C or less, and can prevent that a suspension liquid is concentrated.

  The particle size of the carbon particles is preferably 0.01 μm to 5 μm, more preferably 0.01 μm to 2 μm. When the particle size is large, it becomes a factor that clogs the cells of the resin molded body or inhibits smooth plating, and when it is too small, it is difficult to ensure sufficient conductivity. The type of carbon particles is not particularly limited as long as it can impart conductivity, and for example, carbon black can be preferably used.

  The said binder is not specifically limited, For example, polyolefin and carboxymethylcellulose can be used preferably. Since polyolefin is granular, there is a small gap between the grains even in the suspension. The aluminum plating solution is eroded and electrodeposited in the gap, resulting in the hollow structure of the porous aluminum body. There may be a case where a microporous layer is formed on the surface of the portion. On the other hand, since carboxymethylcellulose is water-soluble, it is considered that no gap is formed as in the case where a conductive layer is formed using polyolefin. For this reason, since the aluminum plating solution does not easily erode in the dense conductive layer produced using carboxymethylcellulose, it is considered that the microporous layer is hardly formed on the surface of the hollow portion of the skeleton of the aluminum porous body.

The application of the carbon particles to the resin molded body can be performed by immersing the target resin molded body in the suspension and performing squeezing and drying.
In the conductive resin molding produced as described above, the basis weight of the conductive layer is preferably 1 g / m ² or more and 20 g / m ² or less. When the basis weight of the conductive layer is 1 g / m ² or more, sufficient conductivity can be imparted to the surface of the resin molded body. Moreover, when the basis weight of the conductive layer is 20 g / m ² or less, the amount of the conductive layer adhering to the surface of the skeleton of the resin molded body is suppressed, and the moisture content of the conductive resin molded body is suppressed. The amount of adsorption can be reduced. From these viewpoints, the basis weight of the conductive layer in the conductive resin molded body is more preferably ² g / m ² or more and 18 g / m ² or less, and 3 g / m ² or more and 15 g / m ² or less. Is more preferable.
In this case, the basis weight of the conductive layer is a foamed urethane having a base material thickness of 1 mm, a porosity of 80% to 98%, and a pore number (number of cells) per inch of 42 to 50. The basis weight when using as a substrate.

(Process for producing a dried conductive resin molding)
In the step of producing the dried conductive resin molded body, the moisture adsorption amount of the conductive resin molded body produced as described above is set to 100 mg / m ² or less. By setting the moisture adsorption amount of the conductive resin molded body to 100 mg / m ² or less, it is possible to make it difficult for the aluminum plating solution to erode into the conductive layer in the subsequent aluminum film forming step. In the step of producing the dried conductive resin molded body, it is preferable that the moisture adsorption amount of the conductive resin molded body is reduced. For example, it is more preferably 70 mg / m ² or less, and 50 mg / m ^2. More preferably, it is as follows.

A method for setting the moisture adsorption amount of the conductive resin molded body to 100 mg / m ² or less is not particularly limited, and examples thereof include heat treatment, treatment under a low dew point, and reduced pressure treatment.
Among the above, heat treatment is most efficient and preferable. In the heat treatment, for example, the conductive resin molded body may be exposed to a temperature of 100 ° C. or higher for 1 minute or longer. More preferable heat treatment conditions are 120 ° C. and 2 minutes or more, and further preferably 120 ° C. and 5 minutes or more.

When the conductive resin molded body is placed under a low dew point to remove moisture, for example, it may be left in an atmosphere having a dew point temperature of 0 ° C. or lower for 24 hours or longer. A more preferable condition is that it is placed in an atmosphere having a dew point temperature of −10 ° C. or lower for 24 hours or longer, and more preferably 24 hours or longer in an atmosphere having a dew point temperature of −30 ° C. or lower.
Moreover, what is necessary is just to leave still for 6 hours or more in the atmosphere of 10 < ⁵ > Pa or less, when carrying out the pressure reduction process of the said conductive resin molding. A more preferable condition is to place in an atmosphere of 10 ⁴ Pa or less for 6 hours or more, and it is even more preferable to place in an atmosphere of 10 ³ Pa or less for 6 hours or more.

(Process of forming aluminum film)
As a method for forming an aluminum film on the surface of the dried conductive resin molded body obtained as described above, a plating method using a molten salt bath is employed.
-Aluminum plating (molten salt plating)-
Electroplating is performed in a molten salt to form an aluminum film on the surface of the dried conductive resin molded body.
By performing aluminum plating in a molten salt bath, even in the case of a substrate having a complicated skeleton structure, such as a resin molded body having a three-dimensional network structure, the aluminum is uniformly thick on the surface of the skeleton. A film can be formed. A direct current is applied in the molten salt using the dried conductive resin molded article as a cathode and aluminum as an anode.

As the molten salt, an organic molten salt which is a eutectic salt of an organic halide and an aluminum halide, or an inorganic molten salt which is a eutectic salt of an alkali metal halide and an aluminum halide can be used. When an organic molten salt bath that melts at a relatively low temperature is used, electrolytic plating can be performed without decomposing the resin molded body as a base material. As the organic halide, imidazolium salt, pyridinium salt and the like can be used. Specifically, 1-ethyl-3-methylimidazolium chloride (EMIC) and butylpyridinium chloride (BPC) are preferable.
Since the molten salt deteriorates when moisture or oxygen is mixed in the molten salt, the plating is preferably performed in an atmosphere of an inert gas such as nitrogen or argon and in a sealed environment.

As the molten salt bath, a molten salt bath containing nitrogen is preferable, and among them, an imidazolium salt bath is preferably used. When a salt that melts at a high temperature is used as the molten salt, the resin dissolves and decomposes in the molten salt faster than the growth of the plated film, and the plated film is formed on the surface of the dried conductive resin molded body. I can't. The imidazolium salt bath can be used without affecting the resin even at a relatively low temperature. As the imidazolium salt, a salt containing an imidazolium cation having an alkyl group at the 1,3-position is preferably used. In particular, an aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl ₃ -EMIC) -based molten salt is used. It is most preferably used because it is highly stable and hardly decomposes. Plating onto foamed urethane resin or foamed melamine resin is possible, and the temperature of the molten salt bath is 10 ° C. or higher and 100 ° C. or lower, preferably 25 ° C. or higher and 45 ° C. or lower. The lower the temperature, the narrower the current density range that can be plated, and the more difficult it is to plate on the entire surface of the dried conductive resin molded body. At a high temperature exceeding 100 ° C., a problem that the shape of the dried conductive resin molded body serving as the substrate is impaired is likely to occur.
Through the above steps, an aluminum-resin structure having a dry conductive resin molded body as a skeleton core is obtained.

(Step of removing the base material)
The method for removing the base material from the aluminum-resin structure obtained as described above is not particularly limited. For example, a heat treatment for heating to 370 ° C. or higher and lower than the melting point of aluminum in a nitrogen atmosphere or the air is performed. It can be done by doing. As a result, the resin is burned out and an aluminum porous body having a hollow skeleton is obtained.

  As described above, the present inventors have intensively studied to further reduce the moisture adsorption amount of the aluminum porous body, and as a result, the microporous layer is formed on the surface of the skeleton of the aluminum porous body obtained by the conventional plating method. It has been found that the reason for the formation is that γ-alumina is produced by the dehydration reaction of boehmite. This γ-alumina is also used as a hygroscopic agent and has been studied for its hygroscopic properties (for example, “Kazuo Kawamura, Harumi Endo,“ Hygroscopic Properties of Boehmite and Anhydrous Alumina ”, Journal of Ceramic Society of Japan 107 [4] pp 335-338 (1998) "," Lee Haiyong, Sadafumi Isshiki, "On the Transformation of γ-Alumina", Production Research, Vol. 11, No. 2, pp. 25-29, 1959 ").

Therefore, the present inventors have further investigated a method for preventing fine irregularities due to γ-alumina from occurring on the surface of the skeleton of the porous aluminum body. As a result, it has been found that there is room for improvement in a conventional method for producing a porous aluminum body having a three-dimensional network structure by a plating method (for example, JP 2012-007233 A).
That is, when heat treatment is performed when removing urethane from the aluminum-resin structure, moisture is contained in the oxide film on the surface of the aluminum film because the removal temperature of urethane is normally 500 ° C. to 660 ° C. Then, dehydration will form a nano-order microporous layer on the surface. For this reason, it is only necessary that boehmite is not formed on the surface of the aluminum film.

By the way, since neither water nor oxygen is present in a plating solution such as a molten salt such as 1-ethyl-3-methylimidazolium chloride and aluminum chloride, an aluminum film formed by molten salt electroplating is an oxide film. It does not have aluminum. Therefore, the surface state can be variously changed by the treatment after plating.
For example, when the aluminum-resin structure on which the aluminum film is formed is washed with pure water immediately after being taken out of the plating solution, an aluminum oxide film containing water is formed on the outermost surface of the plating film. Moreover, it is possible to form an oxide film on the surface of the plating film before the cleaning treatment by blowing dry air having a low dew point immediately after the aluminum-resin structure is taken out of the plating solution. In addition, immediately after the aluminum-resin structure is taken out of the plating solution, it is washed with an organic solvent such as ethanol or xylene and exposed to dry air, so that an oxide film containing almost no water is formed on the surface of the plating film. Is done.

  From the above, in order to produce an aluminum porous body in which fine irregularities are not formed on the surface of the skeleton and the amount of moisture adsorption is smaller, for example, the following is preferable.

− Treatment of plating solution adhering to aluminum-resin structure −
Since the plating solution adheres to the surface of the aluminum-resin structure obtained by subjecting the surface of the resin substrate to molten salt electroplating with aluminum, the plating solution is removed by washing with water, followed by heat treatment. Done. At this time, if the washing process is performed with a large amount of plating solution adhering to the surface of the aluminum-resin structure, the plating solution and water react to generate heat, and the aluminum and water react on the surface of the aluminum film. Boehmite is formed. Then, when the resin is subsequently removed, it is considered that the boehmite is transformed into γ-alumina by being exposed to a high temperature of 500 ° C. or more, and fine irregularities are formed on the skeleton surface.

For this reason, before the aluminum-resin structure is washed with water, it is preferable to perform liquid draining so that the amount of the plating solution adhering to the aluminum film is 0.1 mL / m ² or more and 30 mL / m ² or less. . From the above viewpoint, the amount of the plating solution adhering to the aluminum film is preferably smaller, more preferably 0.1 mL / m ² or more and 10 mL / m ² or less, 0.1 mL / m ² or more, 3 mL / More preferably, it is m ² or less.
The means for draining the plating solution is not particularly limited, for example, by spraying nitrogen gas, argon gas, dry air (dew point -50 ° C. or higher, -30 ° C. or lower) or the like onto the aluminum-resin structure. Can do.

− Drying of dry air onto aluminum and resin structures −
It is also effective to blow dry air with a low dew point immediately after the aluminum-resin structure having an aluminum film formed on the substrate surface is taken out of the plating solution. Thereby, it is possible to prevent the formation of γ-alumina by forming an oxide film on the surface of the aluminum film before the water washing treatment. As the dry air having a low dew point, for example, dry air having a dew point temperature of about −50 ° C. to −30 ° C. can be used.

  Moreover, it is also preferable to remove the plating solution adhering to the aluminum film with an organic solvent before washing the aluminum-resin structure with water. Thereby, the plating solution can be removed without causing the aluminum film and water to react. Then, by exposing the aluminum-resin structure to dry air, an oxide film containing almost no water can be formed on the surface of the aluminum film so that γ-alumina is not formed. As the organic solvent, for example, fluorinated alkenes such as ethanol, xylene, toluene and 2,3,3,4,4,5,5-heptafluoro-1-pentene can be preferably used.

-Removal of resin base material-
As described above, the resin base material can be removed by performing a heat treatment to heat the aluminum-resin structure to 370 ° C. or higher, but if this step is performed in an atmosphere with a high moisture content and a high dew point. Aluminum and water react to form boehmite, which is further transformed into γ-alumina and fine irregularities may be formed on the surface of the skeleton.
For this reason, it is preferable to remove the substrate by heating the resin to 370 ° C. or higher and lower than the melting point of aluminum in an atmosphere having a dew point temperature of 0 ° C. or lower. The dew point temperature of the atmosphere is more preferably −5 ° C. or lower, and further preferably −10 ° C. or lower. In addition, since the dew point temperature at the time of removing the said base material can fully suppress reaction with the water | moisture content in the atmosphere and aluminum, about 30 degreeC, what is necessary is just to perform the said dew point temperature above -30 degreeC. The heating temperature is more preferably 500 ° C. or more and 660 ° C. or less, and further preferably 580 ° C. or more and 630 ° C. or less.

<Porous aluminum body>
The aluminum porous body obtained as described above is an aluminum porous body in which a microporous layer is hardly formed on the surface of the hollow portion inside the skeleton and the amount of moisture adsorption is very small.
Moreover, since the skeleton of the aluminum porous body has a three-dimensional network structure, for example, when the aluminum porous body is used for an electrode of an electrochemical device, the amount of the active material per unit volume can be increased by increasing the amount of active material retained. The utilization factor can be increased, and an electrode having a large capacity can be manufactured.

And since the moisture adsorption amount of the aluminum porous body is small as described above, for example, when the aluminum porous body is used in an environment where moisture is removed like a battery or a capacitor electrode using a non-aqueous electrolyte, It is possible to reduce the burden on the moisture removal process.
For this reason, the moisture adsorption amount of the aluminum porous body is preferably as small as possible, preferably 80 mg / m ² or less, more preferably 70 mg / m ² or less, and further preferably 60 mg / m ² or less, Most preferably, it is 50 mg / m ² or less.
The moisture adsorption amount of the aluminum porous body refers to the amount of moisture per apparent area of the aluminum porous body after being exposed to an atmosphere having a temperature of 20 ° C. and a dew point temperature of 0 ° C. for 24 hours.

  Examples of the electrochemical device using the non-aqueous electrolyte include a lithium battery, a capacitor, a lithium ion capacitor, and a molten salt battery.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, these Examples are illustrations and the manufacturing method of the aluminum porous body of this invention is not limited to these. The scope of the present invention is defined by the scope of the claims, and includes meanings equivalent to the scope of the claims and all modifications within the scope.

[Example 1]
-Preparation of resin molding-
As a resin molded body having a three-dimensional network structure, a urethane foam having a porosity of 96%, a cell number of 46 / inch, a pore diameter of about 550 μm, and a thickness of 1.0 mm is prepared and cut into a 100 mm × 100 mm square. did.
-Carbon paint 1
Carbon paint 1 was prepared by mixing carbon black 13.9% by mass, carboxymethylcellulose 1.7% by mass, water 83.0% by mass, and dispersing agent 1.4% by mass as an additive. Produced. Carbon black having an average primary particle size of 20 nm was used. In addition, ammonium-based carboxymethylcellulose was used as carboxymethylcellulose.

-Conductive resin molding 1-
The urethane foam was dipped in the carbon paint 1 and pulled up, and then dried at 120 ° C. for 1 minute to produce a conductive resin molded body 1. The basis weight of the conductive layer in the conductive resin molded body 1 was 8 g.

-Dry conductive resin molding 1-
The conductive resin molded body 1 produced as described above was heat-treated for 5 minutes on a hot plate at 120 ° C. in an atmosphere having a temperature of 20 ° C. and a dew point temperature of 10 ° C. to produce a dry conductive resin molded body 1.

(Evaluation of moisture adsorption amount of dry conductive resin molding 1)
The dried conductive resin molded article 1 produced as described above was cut out to 4000 mm ² to produce a test piece, and the moisture content was measured by Karl Fischer coulometric titration using a moisture vaporizer heated to 150 ° C. The end condition of the titration was the time when the detected water content became “background value + 0.1 μg / sec”.
As a result, the moisture adsorption amount of the dried conductive resin molded body 1 was 38 mg / m ² .

-Aluminum plating-
After setting the dried conductive resin molded body 1 as a workpiece in a jig having a power feeding function, it is put in a glove box having an argon atmosphere and low moisture (dew point -30 ° C. or less), and a molten salt aluminum having a temperature of 40 ° C. I was immersed in a plating bath (33mol% EMIC-67mol% AlCl 3). The jig on which the workpiece was set was connected to the cathode side of the rectifier, and a counter electrode aluminum plate (purity 99.99 mass%) was connected to the anode side.
Aluminum-resin structure in which an aluminum film having a mass of 140 g / m ² is formed on the surface of the dried conductive resin molded body 1 by plating by applying a direct current having a current density of 6.5 A / dm ² for 20 minutes. Body 1 was obtained. Stirring was performed with a stirrer using a Teflon (registered trademark) rotor. The current density is a value calculated with an apparent area of urethane foam.

-Removal of resin-
The aluminum-resin structure 1 obtained above was taken out of the plating bath and washed with water having a liquid temperature of 15 ° C. in a state where the amount of plating solution deposited was 30 mL / m ² . After the water washing treatment, the aluminum-resin structure was naturally dried and heat-treated at 610 ° C. for 20 minutes in an atmosphere with a dew point temperature of −20 ° C. As a result, the urethane resin was burned out and the aluminum porous body 1 was obtained.

(Evaluation of moisture adsorption amount of aluminum porous body 1)
The aluminum porous body 1 produced as described above was cut out to 2500 mm ² to prepare a test piece, which was allowed to stand for 24 hours in an atmosphere at a temperature of 20 ° C. and a dew point temperature of 0 ° C. Thereafter, the moisture adsorption amount was measured by the Karl Fischer coulometric titration method using a moisture vaporizer in which the test piece (aluminum porous body 1) was heated to 300 ° C. The end condition of the titration was the time when the detected water content became “background value + 0.1 μg / sec”.
As a result, the moisture content of the aluminum porous body 1 was a sufficiently small moisture adsorption amount of 42 mg / m ² .

[Example 2]
A dry conductive resin molded body 2 and a porous aluminum body 2 were produced in the same manner as in Example 1 except that the carbon paint 2 having the following composition was used as the carbon paint.
-Carbon paint 2-
Carbon paint 1 is prepared by mixing carbon black 12.6% by weight, polyolefin 3.1% by weight, water 83.0% by weight, and dispersing agent 1.3% by weight as an additive. did. Carbon black having an average primary particle size of 20 nm was used.

(Evaluation of moisture adsorption amount of the dried conductive resin molding 2)
When the moisture adsorption amount of the dry conductive resin molded body 2 was measured in the same manner as the dry conductive resin molded body 1, the moisture adsorption amount of the dry conductive resin molded body 2 was 52 mg / m ² .
(Evaluation of water adsorption amount of aluminum porous body 2)
When the moisture adsorption amount of the aluminum porous body 2 was measured in the same manner as the aluminum porous body 1, the moisture adsorption amount of the aluminum porous body 2 was 65 mg / m ² .

[Comparative Example 1]
Except that the conductive resin molded body 1 was left to stand for 2 days in a general atmosphere at a temperature of 20 ° C. and a dew point temperature of 10 ° C. without drying (heat treatment), the same as in Example 1 A porous aluminum body A was produced.
In addition, let the conductive resin molding after leaving still in a general atmosphere with a temperature of 20 degreeC and a dew point temperature of 10 degreeC for 2 days be the conductive resin molding A.

(Evaluation of moisture adsorption amount of conductive resin molding A)
When the moisture adsorption amount of the conductive resin molded body A was measured in the same manner as the dry conductive resin molded body 1, the moisture adsorption amount of the conductive resin molded body A was 135 mg / m ² .
(Evaluation of moisture adsorption amount of aluminum porous body A)
When the moisture adsorption amount of the aluminum porous body A was measured in the same manner as the aluminum porous body 1, the moisture adsorption amount of the aluminum porous body A was 87 mg / m ² .

[Comparative Example 2]
Porous aluminum body in the same manner as in Example 2 except that the conductive resin molded body 2 was not subjected to a drying treatment and was left to stand for 2 days in a general atmosphere at a temperature of 20 ° C. and a dew point temperature of 10 ° C. B was produced.
In addition, let the conductive resin molding after leaving still in a general atmosphere with a temperature of 20 degreeC and a dew point temperature of 10 degreeC for 2 days be the conductive resin molding B.

(Evaluation of moisture adsorption amount of conductive resin molding B)
When the moisture adsorption amount of the dry conductive resin molded body B was measured in the same manner as the dry conductive resin molded body 1, the water adsorption amount of the conductive resin molded body B was 162 mg / m ² .
(Evaluation of moisture adsorption amount of aluminum porous body B)
When the moisture adsorption amount of the aluminum porous body B was measured in the same manner as the aluminum porous body 1, the moisture adsorption amount of the aluminum porous body B was 149 mg / m ² .

Claims (4)

A step of producing a conductive resin molding by conducting a conductive treatment by applying a carbon paint on the surface of a resin molding having a three-dimensional network structure; and
Producing a dried conductive resin molded body by setting the moisture adsorption amount of the conductive resin molded body to 100 mg / m ² or less per 1 mm thickness per apparent unit area of the conductive resin molded body;
Forming an aluminum film on the surface of the dried conductive resin molding by molten salt electroplating;
Removing the substrate;
The manufacturing method of the aluminum porous body which has this. In the step of producing the dried conductive resin molded body, the conductive resin molded body is subjected to a heat treatment to determine the moisture adsorption amount of the conductive resin molded body by the thickness per apparent unit area of the conductive resin molded body. The manufacturing method of the aluminum porous body of Claim 1 which makes it 100 mg / m < ² > or less per 1 mm of thickness . 3. The method for producing a porous aluminum body according to claim 1, wherein the conductive resin molded body has a basis weight of a conductive layer of 1 g / m ² or more and 20 g / m ² or less.   The method for producing a porous aluminum body according to any one of claims 1 to 3, wherein the carbon paint contains carboxymethyl cellulose as a binder.