JPWO2015019987A1 - Electrode material for aluminum electrolytic capacitor and method for producing the same - Google Patents

Abstract

The present invention is an electrode material for an aluminum electrolytic capacitor having a sintered layer of at least one powder of aluminum and an aluminum alloy, and ensures an excellent capacitance even when used for a low-voltage capacitor. An electrode material that can be used is provided. Specifically, the present invention provides an electrode material for an aluminum electrolytic capacitor having a sintered layer in which at least one powder of aluminum and an aluminum alloy is sintered via electrically insulating particles.

Description

  The present invention relates to an electrode material used for an aluminum electrolytic capacitor, and more particularly to an anode electrode material used for a low-pressure aluminum electrolytic capacitor and a method for producing the same.

  Aluminum electrolytic capacitors are widely used in various fields because they are inexpensive and can provide a high capacity. Generally, aluminum foil is used as an electrode material for an aluminum electrolytic capacitor.

  The aluminum foil can increase the surface area by performing an etching process to form etching pits. The surface is anodized to form an oxide film, which functions as a dielectric. For this reason, the aluminum foil for electrolytic capacitors (anode foil) according to a use can be manufactured by etching the aluminum foil and subjecting the surface to anodization with various voltages according to the operating voltage. .

  In the etching process of the aluminum foil, the etching process is performed so that optimum etching pits corresponding to the anodic oxidation voltage are formed. Specifically, it is necessary to form a thick oxide film for medium- and high-voltage capacitor applications. Therefore, the etching pit shape is changed to a tunnel type by performing direct current etching so that the etching pit is not filled with a thick oxide film, and the thickness is processed according to the anodizing voltage. On the other hand, in low-voltage capacitor applications, fine etching pits are required, and spongy etching pits are formed mainly by AC etching.

  In the etching treatment, an aqueous hydrochloric acid solution in which sulfuric acid, phosphoric acid, nitric acid or the like is added to hydrochloric acid is mainly used. However, since hydrochloric acid has a large environmental load, it is desired to develop a method for increasing the surface area of the aluminum foil without using the etching process.

  In this regard, Patent Document 1 proposes an aluminum electrolytic capacitor using an aluminum foil having fine aluminum powder adhered to the surface. Further, Patent Document 2 discloses that aluminum which is self-similar in a length range of 2 μm to 0.01 μm and / or an aluminum oxide layer on the surface is formed on one or both sides of a smooth aluminum foil having a foil thickness of 15 μm or more and less than 35 μm. There is disclosed an electrolytic capacitor using an electrode foil to which agglomerates of fine particles made of aluminum and having formed thereon are adhered.

  However, in these documents, since aluminum powder or the like is attached to the aluminum foil by plating and / or vapor deposition, it can be said that it is at least sufficient to substitute for thick etching pits for use in capacitors for medium and high pressures. Absent.

  Patent Document 3 discloses an electrode material for an aluminum electrolytic capacitor, which is an electrode material for an aluminum electrolytic capacitor, and the electrode material is made of at least one sintered body of aluminum and an aluminum alloy. It has been confirmed that the performance higher than the electrode material obtained by the conventional etching process can be obtained.

  However, the electrode material disclosed in Patent Document 3 exhibits excellent performance in medium- and high-voltage capacitor applications, but when used in a low-pressure region, it can exhibit performance higher than that of an electrode material obtained by conventional etching treatment. Not.

  In order to exhibit performance beyond the electrode material obtained by the conventional etching process even when used in a low pressure region, for example, excessive necking (superfiring) is required when sintering at least one powder of aluminum and aluminum alloy. It is conceivable to secure an effective surface area by suppressing the (congeation) as much as possible and reducing the contact area between the powders as much as possible, but no electrode material that has solved such a problem has been reported yet.

JP-A-2-267916 JP 2006-108159 A JP 2008-98279 A

  The present invention is an electrode material for an aluminum electrolytic capacitor having a sintered layer of at least one powder of aluminum and an aluminum alloy, and ensures an excellent capacitance even when used for a low-voltage capacitor. It aims at providing the electrode material which can be performed.

  As a result of intensive studies to achieve the above object, the present inventor has formed the above object in the case where a sintered layer is formed by sintering at least one powder of aluminum and an aluminum alloy together with a specific substance. The present invention has been completed.

That is, this invention relates to the following electrode material for aluminum electrolytic capacitors, and its manufacturing method.
1. An electrode material for an aluminum electrolytic capacitor, comprising a sintered layer in which at least one powder of aluminum and an aluminum alloy is sintered through electrically insulating particles.
2. The electrode material for an aluminum electrolytic capacitor according to Item 1, wherein the weight ratio of the content of the powder and the electrically insulating particles is 1: 2 to 200: 1.
3. Item 3. The electrode material for an aluminum electrolytic capacitor according to Item 1 or 2, wherein the powder has an aspect ratio of 1 to 1000.
4). Item 4. The electrode material for an aluminum electrolytic capacitor according to any one of Items 1 to 3, wherein the powder has an average particle size of 1 to 80 µm.
5). Item 5. The electrode material for an aluminum electrolytic capacitor according to any one of Items 1 to 4, wherein the powder has an average thickness of 0.01 to 80 µm.
6). Item 6. The electrode material for an aluminum electrolytic capacitor according to any one of Items 1 to 5, wherein the electrically insulating particles are a metal oxide or a metal nitride.
7). Item 7. The electrode material for an aluminum electrolytic capacitor according to any one of Items 1 to 6, wherein the electrically insulating particles are at least one selected from the group consisting of alumina, titania, zirconia, and silica.
8). Item 8. The electrode material for an aluminum electrolytic capacitor according to any one of Items 1 to 7, wherein the electrically insulating particles have an average particle size of 0.01 to 10 µm.
9. Item 9. The electrode material for an aluminum electrolytic capacitor according to any one of Items 1 to 8, wherein the sintered layer has an average thickness of 5 to 1000 µm.
10. Item 10. The electrode material for an aluminum electrolytic capacitor according to any one of Items 1 to 9, which has a base material that supports the sintered layer.
11. A first step of forming a film comprising a paste-like composition containing at least one powder of aluminum and an aluminum alloy and electrically insulating particles, and sintering by sintering the film at a temperature of 400 to 660 ° C. A second step of forming a layer;
And a manufacturing method of an electrode material for an aluminum electrolytic capacitor, characterized by not including an etching step.
12 Item 12. The method according to Item 11, further comprising a third step of anodizing the sintered layer.

 Hereinafter, the electrode material of the present invention and the manufacturing method thereof will be described in detail.

Electrode Material for Aluminum Electrolytic Capacitor The electrode material for aluminum electrolytic capacitor of the present invention has a sintered layer in which at least one powder of aluminum and aluminum alloy is sintered via electrically insulating particles (acting as a spacer). It is characterized by. Hereinafter, at least one powder of aluminum and aluminum alloy is also simply referred to as “powder”.

  The electrode material for an aluminum electrolytic capacitor of the present invention having the above characteristics forms a sintered layer by sintering at least one powder of aluminum and an aluminum alloy through electrically insulating particles. The effective surface area is ensured by suppressing excessive necking (over-sintering) of the powders in as much as possible and reducing the contact area between the powders as much as possible. Therefore, even when the electrode material for an aluminum electrolytic capacitor of the present invention is used for a low-voltage capacitor used at a low voltage of 100 V or less, it can exhibit performances higher than that of an electrode material obtained by a conventional etching process.

  As the raw material aluminum powder, for example, aluminum powder having an aluminum purity of 99.8% by weight or more is preferable. Examples of the raw material aluminum alloy powder include silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), chromium (Cr), zinc (Zn), and titanium (Ti). ), Vanadium (V), gallium (Ga), nickel (Ni), boron (B), an alloy containing one or more elements such as zirconium (Zr). The content of these elements in the aluminum alloy is preferably 100 ppm by weight or less, particularly 50 ppm by weight or less.

  The powder preferably has an average particle size of 1 to 80 μm. In particular, when the average particle diameter of the powder is 1 to 10 μm, the obtained electrode material can be suitably used as an electrode material for an aluminum electrolytic capacitor for low pressure applications of 100 V or less.

  The average particle size of the powder before sintering in this specification is 50% of the total number of particles in the particle size distribution curve obtained by determining the particle size and the number of particles corresponding to the particle size by laser diffraction. It is the particle diameter of the particle | grains applicable to. Moreover, the average particle diameter of the powder after sintering is measured by observing the cross section of the sintered layer with a scanning electron microscope. In the cross-sectional observation, the maximum diameter (major axis) of each powder particle is the particle diameter of the powder, the particle diameter of any 50 powders is measured, and the arithmetic average of these is the average of the powder after sintering The particle size.

  The shape of the powder is not particularly limited, and any of a spherical shape, an indefinite shape, a scale shape (flake shape), a fiber shape and the like can be suitably used. In general, when scaly powder is used, oversintering is likely to occur, and it is difficult to ensure the effective surface area of the electrode material. Even when using this powder, it is easy to secure an effective surface area of the electrode material by suppressing oversintering.

  What is manufactured by a well-known method can be used for the said powder. For example, an atomizing method, a melt spinning method, a rotating disk method, a rotating electrode method, a rapid solidification method, and the like can be mentioned. For industrial production, the atomizing method, particularly the gas atomizing method is preferable. That is, it is desirable to use a powder obtained by atomizing a molten metal.

  The average particle diameter of the powder is preferably 1 to 80 μm, more preferably 1 to 10 μm, when it is a spherical particle. If the average particle size is smaller than 1 μm, the desired withstand voltage may not be obtained. On the other hand, if the average particle size is larger than 80 μm, the desired capacitance may not be obtained.

  When the powder is indefinite shape, scaly (flakes) or fibrous, the aspect ratio (average particle size / average thickness) is preferably 1-1000. If the aspect ratio is greater than 1000, defects are likely to occur in the drying and degreasing processes of the film in the first step of the manufacturing method described later. Among the above aspect ratios, the ratio of 100 to 1,000 is particularly preferable because a higher capacitance can be obtained than the electrode material obtained by the conventional etching process even in the low pressure region. The average thickness of the powder can be measured by observing a cross section of the powder with a scanning electron microscope. In the case of before sintering, the powder is appropriately mixed with a resin or a solvent to form a coating film, and the cross section of the coating film is observed. In the case of sintering, a cross-sectional observation of the sintered layer is performed. In these cross-sectional observations, the minimum diameter of each powder is taken as the thickness of the powder, the thicknesses of any 50 powders are measured, and the arithmetic average of these is taken as the average thickness of the powder. The average thickness of the powder is preferably 0.01 to 80 μm. When the average thickness of the powder is smaller than 0.01 μm, a desired withstand voltage may not be obtained. On the other hand, when the average thickness of the powder is larger than 80 μm, a desired capacitance may not be obtained.

  The electrically insulating particles are particles that suppress oversintering of the powders by interposing as a spacer between the powders during sintering of the powders, and can secure an effective surface area and capacitance of the electrode material. I just need it. Such electrically insulating particles are preferably metal compound particles (oxide, nitride, etc.), and specifically, at least one metal compound selected from alumina, titania, zirconia and silica. Particles are preferred.

  These particles have electrical insulation properties and a high melting point (about 2000 ° C.), and themselves do not sinter with the powder, and can intervene as spacers during the sintering of the powder as well as the electrical characteristics of the electrode material. It is preferable at the point which does not have a possibility that it may have a bad influence on a product.

  The average particle diameter of the electrically insulating particles is not limited, but is preferably 0.01 to 10 μm, more preferably 0.1 to 1 μm. The average particle diameter of the electrically insulating particles can be measured by the same method as that for the powder.

  The weight ratio of the content of the powder and the electrically insulating particles in the sintered layer is not limited. For example, the powder: the electrically insulating particles is preferably 1: 2 to 200: 1. : 1 to 20: 1 is more preferable, and 3: 1 to 10: 1 is particularly preferable. The volume ratio of the content of the powder and the electrically insulating particles is preferably the powder: the electrically insulating particles = 3: 4 to 300: 1, and preferably 3: 1 to 30: 1. Is more preferable, and 9: 2 to 15: 1 is particularly preferable.

  By setting the content ratio (weight ratio, volume ratio) within this range, it is easy to ensure an effective surface area of the electrode material. In addition, when the aspect ratio of the powder is 3 to 1000, the weight ratio is preferably in the range of 1: 2 to 200: 1, and when the aspect ratio of the powder is less than 3 (that is, 1 or more and less than 3). The weight ratio is preferably in the range of 2: 1 to 200: 1. This is considered to be because the allowable content of the electrically insulating particles is increased when the aspect ratio of the powder is 3 or more.

  When the weight ratio exceeds 1: 2 and the number of electrically insulating particles increases, the ratio of the electrically insulating particles increases so that sintering of the powders may be difficult. On the other hand, when the weight ratio is increased to about 250: 1, the amount of electrically insulating particles becomes too small and the effect of improving the capacitance may not be sufficiently obtained.

  As described above, conventionally, when scaly powder (aluminum flakes) is used, the specific surface area is larger than that of spherical powder, and the orientation of aluminum flakes after coating a paste containing aluminum flakes is high. It is considered that it is easy to oversinter at the time of sintering because it is likely to be in surface contact, and it is difficult to ensure an effective specific surface area. However, oversintering can be suppressed during sintering by sintering via electrically insulating particles as described below.

  FIG. 1 shows a scanning electron microscope observation image of a cross section of a conventional sintered layer (not including electrically insulating particles) using aluminum flakes. Further, FIG. 2 shows a scanning electron microscope observation image of the cross section of the sintered layer of the electrode material of the present invention using aluminum flakes and electrically insulating particles.

  In FIG. 1, the gap between the aluminum flakes is crushed, and the surface area of the aluminum flakes is not fully utilized. On the other hand, in FIG. 2, it can be confirmed that electrically insulating particles have entered between the aluminum flakes and an appropriate space is maintained between the flakes. As a result, the large specific surface area of the aluminum flakes can be utilized efficiently, and the capacitance can be dramatically improved even when used for low pressure applications. The effect of using electrostatic insulating particles as a spacer to increase the capacitance is not limited to the use of scaly powders, but also when using powders of various shapes. Has been confirmed.

  The shape of the sintered layer is not particularly limited, but is generally preferably a foil shape having an average thickness of 5 to 1000 μm, particularly 5 to 50 μm. The average thickness is an average of 10 measured values measured with a micrometer.

  The electrode material of the present invention may have a base material that supports the sintered layer. As the base material, for example, an aluminum foil can be suitably used.

  The aluminum foil as the substrate is not particularly limited, and pure aluminum or an aluminum alloy can be used. The aluminum foil used in the present invention is composed of silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), chromium (Cr), zinc (Zn), titanium ( The content of the aluminum alloy or the above unavoidable impurity elements to which at least one alloy element of Ti), vanadium (V), gallium (Ga), nickel (Ni), boron (B) is added within the necessary range is limited. Also included aluminum.

  Although the thickness of an aluminum foil is not specifically limited, It is preferable to set it as the range of 5-100 micrometers, especially 10-50 micrometers.

  What was manufactured by a well-known method can be used for said aluminum foil. For example, a molten aluminum or aluminum alloy having the above predetermined composition is prepared, and an ingot obtained by casting the molten metal is appropriately homogenized. Thereafter, an aluminum foil can be obtained by subjecting the ingot to hot rolling and cold rolling.

  In addition, you may perform an intermediate annealing process in the range of 50-500 degreeC, especially 150-400 degreeC in the middle of said cold rolling process. Further, after the cold rolling step, a soft foil may be obtained by performing an annealing treatment within a range of 150 to 650 ° C, particularly 350 to 550 ° C.

  When the electrode material of the present invention uses a base material, the sintered layer is formed on one side or both sides of the base material. When forming a sintered layer on both surfaces of a base material, it is preferable to form the sintered layer of the said average thickness so that it may become a symmetrical form on both surfaces of a base material, respectively.

  Even when the electrode material of the present invention is used for a low-voltage capacitor used at a low voltage of 100 V or less, it can exhibit a performance higher than that of an electrode material obtained by a conventional etching process. It can utilize suitably for the use of.

  When the electrode material of the present invention is used as an electrode for an aluminum electrolytic capacitor, the electrode material can be used without etching treatment. That is, the electrode material of the present invention can be used as an electrode (electrode foil) as it is or without being subjected to etching treatment or by anodizing treatment.

  An anode foil using the electrode material of the present invention and a cathode foil are laminated with a separator interposed therebetween, and wound to form a capacitor element. The capacitor element is impregnated with an electrolytic solution, and the capacitor element includes the electrolytic solution. Is stored in an exterior case, and the case is sealed with a sealing body to obtain an electrolytic capacitor.

Method for producing electrode material for aluminum electrolytic capacitor The method for producing the electrode material for aluminum electrolytic capacitor of the present invention comprises:
A first step of forming a film comprising a paste-like composition containing at least one powder of aluminum and an aluminum alloy and electrically insulating particles, and sintering by sintering the film at a temperature of 400 to 660 ° C. A second step of forming a layer;
And an etching process is not included.

In the following, each process will be described separately.
(First step)
The first step forms a film made of a paste-like composition containing at least one powder of aluminum and an aluminum alloy and electrically insulating particles.

  As the composition (component) of aluminum and aluminum alloy, those listed above can be used. As the powder, for example, pure aluminum powder having an aluminum purity of 99.8% by weight or more is preferably used. In addition, as the electrically insulating particles, those listed above can be used. Furthermore, when forming a film, when using a substrate, those listed above can be used.

  The paste composition may contain a resin binder, a solvent, a sintering aid, a surfactant, and the like as necessary in addition to the powder and the electrically insulating particles. Any of these may be known or commercially available. In particular, it is preferable to use at least one of a resin binder and a solvent as a paste-like composition, whereby a film can be efficiently formed.

  The resin binder is not limited. For example, carboxy-modified polyolefin resin, vinyl acetate resin, vinyl chloride resin, vinyl chloride copolymer resin, vinyl alcohol resin, butyral resin, vinyl fluoride resin, acrylic resin, polyester resin, urethane resin A synthetic resin such as epoxy resin, urea resin, phenol resin, acrylonitrile resin, cellulose resin, paraffin wax, polyethylene wax, or natural resin such as wax, tar, glue, urushi, pine resin, beeswax, or wax can be preferably used.

  These resin binders are classified into those that volatilize when heated, depending on the molecular weight, the type of resin, etc., and those that remain together with the aluminum powder due to thermal decomposition, and can be used properly according to the desired electrostatic properties. it can.

  Also, known solvents can be used. For example, in addition to water, organic solvents such as ethanol, toluene, ketones, and esters can be used.

  In forming the film, the paste composition can be formed by using a coating method such as roller, brush, spray, dipping or the like, or can be formed by a known printing method such as silk screen printing.

  When a substrate is used, the film is formed on one side or both sides of the substrate. When forming on both surfaces, it is preferable to arrange | position a film | membrane symmetrically on both sides of a base material. Although the thickness of the film is not limited, it is preferable that the sintered layer obtained after sintering has an average thickness of 5 to 1000 μm, particularly 5 to 50 μm.

The film may be dried at a temperature within the range of 20 to 300 ° C., if necessary.
(Second step)
A 2nd process forms a sintered layer by sintering a film | membrane at the temperature of 400-660 degreeC.

  The sintering temperature is 400 to 660 ° C, preferably 450 to 600 ° C. Although sintering time changes with sintering temperature etc., it can usually be suitably determined within the range of about 5 to 24 hours.

  The sintering atmosphere is not particularly limited, and may be any one of a vacuum atmosphere, an inert gas atmosphere, an oxidizing gas atmosphere (air), a reducing atmosphere, etc., and particularly a vacuum atmosphere or a reducing atmosphere. Is preferred. The pressure condition may be normal pressure, reduced pressure or increased pressure.

In addition, it is preferable to perform the heat processing (degreasing process) for 5 hours or more in a temperature range of 100-600 degreeC previously before a 2nd process after a 1st process. The heat treatment atmosphere is not particularly limited, and may be any of a vacuum atmosphere, an inert gas atmosphere, or an oxidizing gas atmosphere, for example. The pressure condition may be normal pressure, reduced pressure, or increased pressure.
(Third step)
In the second step, the electrode material of the present invention is obtained. This can be used as it is as an electrode for an aluminum electrolytic capacitor (electrode foil) without etching. On the other hand, the electrode material can be formed as an electrode by subjecting it to an anodization treatment as a third step as necessary, thereby forming a dielectric.

The anodizing treatment conditions are not particularly limited, but are usually from 10 mA / cm ^{2 to} 400 mA / cm ^{2 in} a boric acid solution or an ammonium adipate aqueous solution having a concentration of 0.01 mol to 5 mol and a temperature of 30 ° C. to 100 ° C. What is necessary is just to apply the electric current of about 5 minutes or more.

  The electrode material for an aluminum electrolytic capacitor of the present invention forms a sintered layer by sintering at least one powder of aluminum and an aluminum alloy through electrically insulating particles. The effective surface area is ensured by suppressing excessive necking (over-sintering) as much as possible and reducing the contact area between the powders as much as possible. Therefore, even when the electrode material for an aluminum electrolytic capacitor of the present invention is used for a low-voltage capacitor used at a low voltage of 100 V or less, it can exhibit performances higher than that of an electrode material obtained by a conventional etching process.

It is a figure which shows the scanning electron microscope image of the cross section of the conventional sintered layer (it does not contain an electrically insulating particle | grain) which uses scale-like powder (aluminum flakes). It is a figure which shows the scanning electron microscope observation image of the cross section of the sintered layer of this invention using scaly powder (aluminum flakes) and an electrically insulating particle | grain.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Examples 1-1 to 1-5 and Comparative Example 1-1
Uniformly disperse aluminum powder with an average particle size of 3 μm (high-purity aluminum powder of 99.99% or more, aspect ratio (average particle size / average thickness) 1) and alumina particles with an average particle size of 0.5 μm in the following ratio: A sintered body was produced in which the coated film was laminated on both sides of a 20 μm aluminum foil base material (high purity aluminum foil of 99.99% or more) by 50 μm. The average particle size was measured using a microtrack manufactured by Nikkiso Co., Ltd.

In addition, an anodic oxidation treatment was performed using an ammonium adipate aqueous solution. The conditions of the anodizing treatment were such that the concentration of the aqueous solution was 0.3 mol, the temperature was 60 ° C., and a current of 25 mA / cm ² was applied for 10 minutes.

Ratio of aluminum powder to alumina particles (aluminum powder: alumina particles)
Example 1-1 200: 1 (weight ratio), 300: 1 (volume ratio)
Example 1-2 20: 1 (weight ratio), 30: 1 (volume ratio)
Example 1-3 10: 1 (weight ratio), 15: 1 (volume ratio)
Example 1-4 5: 1 (weight ratio), 15: 2 (volume ratio)
Example 1-5 2: 1 (weight ratio), 3: 1 (volume ratio)
Comparative Example 1-1 (Blank test: “BL”) Aluminum powder 100%
The capacitance of each electrode material is shown in Table 1 below.

  When the weight ratio of aluminum powder: alumina particles is in the range of 2: 1 to 200: 1, the capacity is higher in all voltage regions than BL.

Examples 2-1 to 2-5 and Comparative Example 2-1
Aluminum powder having an average particle diameter of 80 μm (high-purity aluminum powder of 99.99% or more, aspect ratio (average particle diameter / average thickness) 1) and alumina particles having an average particle diameter of 5 μm were uniformly dispersed at the following ratio: A sintered body was produced in which the coating film was laminated on both sides by 100 μm on a 20 μm aluminum foil base material (high purity aluminum foil of 99.99% or more).

In addition, an anodic oxidation treatment was performed using an ammonium adipate aqueous solution. The conditions of the anodizing treatment were such that the concentration of the aqueous solution was 0.3 mol, the temperature was 60 ° C., and a current of 25 mA / cm ² was applied for 10 minutes.

Ratio of aluminum powder to alumina particles (aluminum powder: alumina particles)
Example 2-1 200: 1 (weight ratio), 300: 1 (volume ratio)
Example 2-2 20: 1 (weight ratio), 30: 1 (volume ratio)
Example 2-3 10: 1 (weight ratio), 15: 1 (volume ratio)
Example 2-4 5: 1 (weight ratio), 15: 2 (volume ratio)
Example 2-5 2: 1 (weight ratio), 3: 1 (volume ratio)
Comparative Example 2-1 (BL) Aluminum powder 100%
The capacitance of each electrode material is shown in Table 2 below.

  The same tendency as in Examples 1-1 to 1-5 was obtained even in the sintered bodies with different particle sizes and lamination thicknesses.

Examples 3-1 to 3-7 and Comparative Example 3-1
Coating in which aluminum flakes having an average particle diameter of 5 μm and aspect ratio (average particle diameter / average thickness) = 5 (5 μm / 1 μm) and alumina particles having an average particle diameter of 0.5 μm are uniformly dispersed in the following ratio: A sintered body was prepared in which the film was laminated on both sides by 50 μm on a 20 μm aluminum foil base material (high purity aluminum foil of 99.99% or more).

In addition, an anodic oxidation treatment was performed using an ammonium adipate aqueous solution. The conditions of the anodizing treatment were such that the concentration of the aqueous solution was 0.3 mol, the temperature was 60 ° C., and a current of 25 mA / cm ² was applied for 10 minutes.

Ratio of aluminum flakes to alumina particles (aluminum flakes: alumina particles)
Example 3-1 200: 1 (weight ratio), 300: 1 (volume ratio)
Example 3-2 20: 1 (weight ratio), 30: 1 (volume ratio)
Example 3-3 10: 1 (weight ratio), 15: 1 (volume ratio)
Example 3-4 5: 1 (weight ratio), 15: 2 (volume ratio)
Example 3-5 2: 1 (weight ratio), 3: 1 (volume ratio)
Example 3-6 1: 1 (weight ratio), 3: 2 (volume ratio)
Example 3-7 1: 2 (weight ratio), 3: 4 (volume ratio)
Comparative Example 3-1 (BL) 100% aluminum flakes
The capacitance of each electrode material is shown in Table 3 below.

  When aluminum flakes were used, the capacity was increased by about 80% from BL. It can be seen that when the scaly powder (aluminum flakes) is used, the effect of using the electrically insulating particles (alumina particles) in combination is larger than when the spherical powder is used.

Examples 4-1 to 4-7 and Comparative Example 4-1
An aluminum flake having an average particle diameter of 5 μm and an aspect ratio (average particle diameter / average thickness) = 100 (5 μm / 0.05 μm) and alumina particles having an average particle diameter of 0.01 μm are uniformly dispersed in the following ratio. A sintered body was produced in which the coated film was laminated on both sides by 50 μm on a 20 μm aluminum foil base material (high purity aluminum foil of 99.99% or more).

In addition, an anodic oxidation treatment was performed using an ammonium adipate aqueous solution. The conditions of the anodizing treatment were such that the concentration of the aqueous solution was 0.3 mol, the temperature was 60 ° C., and a current of 25 mA / cm ² was applied for 10 minutes.

Ratio of aluminum flakes to alumina particles (aluminum flakes: alumina particles)
Example 4-1 200: 1 (weight ratio), 300: 1 (volume ratio)
Example 4-2 20: 1 (weight ratio), 30: 1 (volume ratio)
Example 4-3 10: 1 (weight ratio), 15: 1 (volume ratio)
Example 4-4 5: 1 (weight ratio), 15: 2 (volume ratio)
Example 4-5 2: 1 (weight ratio), 3: 1 (volume ratio)
Example 4-6 1: 1 (weight ratio), 3: 2 (volume ratio)
Example 4-7 1: 2 (weight ratio), 3: 4 (volume ratio)
Comparative Example 4-1 (BL) 100% aluminum flakes
The capacitance of each electrode material is shown in Table 4 below.

  Aluminum flakes having an extremely large aspect ratio (thin thickness and large specific surface area) have a low capacity in the BL state. This is because the cross-sectional state of the sintered layer is as shown in FIG. However, by dispersing alumina particles as spacers, the low pressure capacity (5 V) is up to 800 times.

This capacity is far higher than the maximum capacity (5 V, 3600 μF / 10 cm ² ) of an electrode material using an aluminum foil (hereinafter referred to as “etched foil”) obtained by a conventional etching process.

  The reason why the value of the 100V capacity is low is considered that it is difficult to form a sufficiently thick oxide film having a withstand voltage of 100V with aluminum flakes having a thickness of less than 0.2 μm.

Examples 5-1 to 5-7 and Comparative Example 5-1
Coating film in which aluminum flakes having an average particle diameter of 3 μm and aspect ratio (average particle diameter / average thickness) = 3 (3 μm / 1 μm) and alumina particles having an average particle diameter of 0.5 μm are uniformly dispersed in the following weight ratio A sintered body was prepared by laminating a laminate of 50 μm each on a 20 μm aluminum foil base material (high purity aluminum foil of 99.99% or more).

In addition, an anodic oxidation treatment was performed using an ammonium adipate aqueous solution. The conditions of the anodizing treatment were such that the concentration of the aqueous solution was 0.3 mol, the temperature was 60 ° C., and a current of 25 mA / cm ² was applied for 10 minutes.

Ratio of aluminum flakes to alumina particles (aluminum flakes: alumina particles)
Example 5-1 200: 1 (weight ratio), 300: 1 (volume ratio)
Example 5-2 20: 1 (weight ratio), 30: 1 (volume ratio)
Example 5-3 10: 1 (weight ratio), 15: 1 (volume ratio)
Example 5-4 5: 1 (weight ratio), 15: 2 (volume ratio)
Example 5-5 2: 1 (weight ratio), 3: 1 (volume ratio)
Example 5-6 1: 1 (weight ratio), 3: 2 (volume ratio)
Example 5-7 1: 2 (weight ratio), 3: 4 (volume ratio)
Comparative Example 5-1 (BL) 100% aluminum flakes

  The same tendency was obtained even when using aluminum flakes having a smaller average particle size as compared with Examples 3-1 to 3-7.

Examples 6-1 to 6-7 and Comparative Example 6-1
Coating film in which aluminum flakes having an average particle diameter of 10 μm and aspect ratio (average particle diameter / average thickness) = 10 (10 μm / 1 μm) and alumina particles having an average particle diameter of 0.5 μm are uniformly dispersed in the following weight ratio A sintered body was prepared by laminating a laminate of 50 μm each on a 20 μm aluminum foil base material (high purity aluminum foil of 99.99% or more).

In addition, an anodic oxidation treatment was performed using an ammonium adipate aqueous solution. The conditions of the anodizing treatment were such that the concentration of the aqueous solution was 0.3 mol, the temperature was 60 ° C., and a current of 25 mA / cm ² was applied for 10 minutes.

Ratio of aluminum flakes to alumina particles (aluminum flakes: alumina particles)
Example 6-1 200: 1 (weight ratio), 300: 1 (volume ratio)
Example 6-2 20: 1 (weight ratio), 30: 1 (volume ratio)
Example 6-3 10: 1 (weight ratio), 15: 1 (volume ratio)
Example 6-4 5: 1 (weight ratio), 15: 2 (volume ratio)
Example 6-5 2: 1 (weight ratio), 3: 1 (volume ratio)
Example 6-6 1: 1 (weight ratio), 3: 2 (volume ratio)
Example 6-7 1: 2 (weight ratio), 3: 4 (volume ratio)
Comparative Example 6-1 (BL) 100% aluminum flakes

  The same tendency was obtained even when using aluminum flakes having a larger average particle size than Examples 3-1 to 3-7.

Examples 7-1 to 7-7 and Comparative Example 7-1
A coating film in which aluminum flakes having an average particle diameter of 5 μm and aspect ratio (average particle diameter / average thickness) = 5 (5 μm / 1 μm) and titania particles having an average particle diameter of 0.5 μm are uniformly dispersed in the following weight ratio. A sintered body was prepared by laminating a laminate of 50 μm each on a 20 μm aluminum foil base material (high purity aluminum foil of 99.99% or more).

In addition, an anodic oxidation treatment was performed using an ammonium adipate aqueous solution. The conditions of the anodizing treatment were such that the concentration of the aqueous solution was 0.3 mol, the temperature was 60 ° C., and a current of 25 mA / cm ² was applied for 10 minutes.

Ratio of aluminum flakes to titania particles (aluminum flakes: titania particles)
Example 7-1 200: 1 (weight ratio), 300: 1 (volume ratio)
Example 7-2 20: 1 (weight ratio), 30: 1 (volume ratio)
Example 7-3 10: 1 (weight ratio), 15: 1 (volume ratio)
Example 7-4 5: 1 (weight ratio), 15: 2 (volume ratio)
Example 7-5 2: 1 (weight ratio), 3: 1 (volume ratio)
Example 7-6 1: 1 (weight ratio), 3: 2 (volume ratio)
Example 7-7 1: 2 (weight ratio), 3: 4 (volume ratio)
Comparative Example 7-1 (BL) 100% aluminum flakes

  The value of the capacity is almost the same as in Examples 3-1 to 3-7. It can be seen that even if it is not alumina particles, it can function as a spacer as long as it has the same particle size and electrical insulation.

Examples 8-1 to 8-9 and comparative examples 8-1 to 8-2
A coating film in which the following aluminum powders (1) to (9) and alumina particles having an average particle diameter of 0.01 μm are dispersed at a ratio of 10: 1 (weight ratio) is applied to a 20 μm aluminum foil base (99.99% or more) A high-purity aluminum foil) was prepared by laminating 50 μm on both sides.
(1) Example 8-1 Average particle size = 3 μm Aluminum powder with aspect ratio 1 (2) Example 8-2 Average particle size = 3 μm Aluminum flakes with aspect ratio 3 (3 μm / 1 μm) (3) Example 8- 3 Average particle size = 3μm Aluminum flakes with aspect ratio 25 (3μm / 0.12μm) (4) Example 8-4 Average particle size = 3μm Aluminum flakes with aspect ratio 60 (3μm / 0.05μm) (5) Example 8- 5 Average particle size = 5 μm Aluminum flakes with aspect ratio 5 (5 μm / 1 μm) (6) Example 8-6 Average particle size = 5 μm Aluminum flakes with aspect ratio 100 (5 μm / 0.05 μm) (7) Example 8-7 Average particle size = 10 μm Aluminum flakes with aspect ratio 25 (10 μm / 0.4 μm) (8) Example 8-8 Average particle size = 10 μm Aluminum flakes with aspect ratio 200 (10 μm / 0.05 μm) (9) Example 8-9 Average particle size = 10μm Aluminum flakes with an aspect ratio of 1000 (10μm / 0.01μm) Comparative example 8-1 Capacity comparison example with the highest level of etched foil 8-2 (BL) Average particle size of 3μm Luminium powder (conventional laminated foil with aluminum powder only)

  A high capacity can be obtained by dispersing alumina particles having an average particle diameter of 0.01 μm with respect to aluminum powder having various particle diameters and aspect ratios. It can also be seen that the larger the aspect ratio, the greater the effect.

  In Comparative Example 8-2 (BL), it does not reach the maximum capacity of the etched foil, but in Example 8-7, it exceeds the maximum capacity of the etched foil in all voltage regions of 100 V or less. Examples 8-3, 8-4, 8-6, and 8-8 have excellent capacity at 10 V or less. When the thickness of the aluminum flakes is less than 0.02 μm as in Example 8-9, the withstand voltage film having a sufficient thickness is not formed, so that the capacity becomes low even at 10V.

  Examples 8-2 and 8-5 also have values exceeding the etched foil in the 100V region. The capacity of Example 8-1 also tends to be higher than that of BL. For example, the capacity value of 150 V is 51.2 μF, which is confirmed to exceed the capacity of the etched foil (about 48 μF).

  By selecting a voltage region suitable for each aluminum powder, an electrode having a higher capacity than the etched foil can be obtained in any voltage region. Aluminum flakes having an aspect ratio of 1000 are liable to cause coating drying failure and degreasing failure during heat treatment in the production process of the laminated foil, and it is difficult to obtain a stable product.

Examples 9-1 to 9-9 and comparative examples 9-1 to 9-2
A coating film in which the following aluminum powders (1) to (9) and alumina particles having an average particle diameter of 0.5 μm are dispersed at a ratio of 10: 1 (weight ratio) is applied to a 20 μm aluminum foil base material (99.99% or more) A high-purity aluminum foil) was prepared by laminating 50 μm on both sides.
(1) Example 9-1 Average particle size = 3 μm Aluminum powder with aspect ratio 1 (2) Example 9-2 Average particle size = 3 μm Aluminum flakes with aspect ratio 3 (3 μm / 1 μm) (3) Example 9- 3 Average particle size = 3μm Aluminum flakes with aspect ratio 25 (3μm / 0.12μm) (4) Example 9-4 Average particle size = 3μm Aluminum flakes with aspect ratio 60 (3μm / 0.05μm) (5) Example 9- 5 Average particle size = 5 μm Aluminum flakes with aspect ratio 5 (5 μm / 1 μm) (6) Example 9-6 Average particle size = 5 μm Aluminum flakes with aspect ratio 100 (5 μm / 0.05 μm) (7) Example 9-7 Average particle size = 10 μm Aluminum flakes with aspect ratio 25 (10 μm / 0.4 μm) (8) Example 9-8 Average particle size = 10 μm Aluminum flakes with aspect ratio 200 (10 μm / 0.05 μm) (9) Example 9-9 Average particle size = 10μm Aluminum flakes with an aspect ratio of 1000 (10μm / 0.01μm) Comparative example 9-1 Capacity comparison example with the highest level of etched foil 9-2 (BL) Average particle size of 3μm with an aspect ratio of 1 Aluminum powder (conventional laminated foil only aluminum powder)

  The results when using alumina particles having an average particle diameter of 0.5 μm are the same as those in Examples 8-1 to 8-9.

Claims (12)

  An electrode material for an aluminum electrolytic capacitor, comprising a sintered layer in which at least one powder of aluminum and an aluminum alloy is sintered through electrically insulating particles.   The electrode material for an aluminum electrolytic capacitor according to claim 1, wherein a weight ratio of the content of the powder and the electrically insulating particles is 1: 2 to 200: 1.   The electrode material for aluminum electrolytic capacitors according to claim 1 or 2, wherein the powder has an aspect ratio of 1 to 1000.   The electrode material for aluminum electrolytic capacitors according to any one of claims 1 to 3, wherein the powder has an average particle size of 1 to 80 µm.   The electrode material for an aluminum electrolytic capacitor according to any one of claims 1 to 4, wherein the powder has an average thickness of 0.01 to 80 µm. The electrode material for an aluminum electrolytic capacitor according to claim 1, wherein the electrically insulating particles are a metal oxide or a metal nitride.   The electrode material for an aluminum electrolytic capacitor according to any one of claims 1 to 6, wherein the electrically insulating particles are at least one selected from the group consisting of alumina, titania, zirconia and silica.   The electrode material for aluminum electrolytic capacitors according to any one of claims 1 to 7, wherein an average particle diameter of the electrically insulating particles is 0.01 to 10 µm.   The electrode material for an aluminum electrolytic capacitor according to claim 1, wherein the sintered layer has an average thickness of 5 to 1000 μm.   The electrode material for aluminum electrolytic capacitors according to any one of claims 1 to 9, comprising a base material that supports the sintered layer. A first step of forming a film comprising a paste-like composition containing at least one powder of aluminum and an aluminum alloy and electrically insulating particles, and sintering by sintering the film at a temperature of 400 to 660 ° C. A second step of forming a layer;
And a manufacturing method of an electrode material for an aluminum electrolytic capacitor, characterized by not including an etching step.   The manufacturing method according to claim 11, further comprising a third step of anodizing the sintered layer.

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