JP5063057B2 - Aluminum material for electrolytic capacitor electrode, method for producing electrode material for electrolytic capacitor, electrode material for electrolytic capacitor, and aluminum electrolytic capacitor - Google Patents

Description

  The present invention relates to an aluminum material for electrolytic capacitor electrodes, a method for producing an electrode material for electrolytic capacitors, an electrode material for electrolytic capacitors, and an aluminum electrolytic capacitor.

  In this specification, the term “aluminum” is used to include both aluminum and its alloys, and the aluminum material includes at least an aluminum foil, an aluminum plate, and a molded body thereof.

An aluminum material generally used as an electrode of an aluminum electrolytic capacitor is subjected to an electrochemical or chemical etching treatment in order to increase the surface expansion ratio and increase the capacitance. Various methods have been proposed to increase the surface expansion ratio and increase the capacitance by generating etch pits formed by this etching process with high density and uniformity. In addition to limiting the contents of impurity elements Fe, Si, and Cu, a method of adding various elements other than these and limiting the contents is known. For example, a method for limiting the content of Ti, V, Cr, Mn, Zr, Na, Ga, and Mg (for example, Patent Document 1) and a method for appropriately adding Ti, V, and Zr (for example, Patent Document 2) are disclosed. Has been.
Japanese Patent No. 3370246 JP 2001-155970 A

  However, in the method described in the above-mentioned patent document, there is a limit to the generation of etch pits with high density and uniformity in an aluminum material, which is sufficient for the recent demand for higher capacitance of electrolytic capacitors. It was not something that could respond.

  The present invention has been made in view of such a situation, and is an aluminum for an electrolytic capacitor electrode that can increase etch area by increasing the density and uniformity of etch pits, thereby increasing the capacitance. An object of the present invention is to provide an electrode material for an electrolytic capacitor, an electrode material for an electrolytic capacitor, and an aluminum electrolytic capacitor.

  In order to achieve the object, the aluminum material for electrolytic capacitor electrodes of the present invention has a configuration described in the following (1) to (9).

  (1) Aluminum purity is 99.9 mass% or more, Ti is over 0.0005 mass% and 0.0025 mass% or less, Zn is 0.0004 mass% or more and 0.006 mass% or less, and Ga is 0.002 mass% or less, V Is an aluminum material for an electrolytic capacitor electrode, which is regulated to 0.001% by mass or less, Zr to 0.001% by mass or less, and Cr to 0.001% by mass or less.

  (2) Aluminum purity is 99.9% by mass or more, Ti is over 0.0005% by mass and 0.0025% by mass or less, Zn is 0.0004% by mass to 0.006% by mass and Si content is 0.0003% by mass to 0.008% by mass Hereinafter, Fe content is 0.0005 mass% or more and 0.008 mass% or less, Cu content is 0.001 mass% or more and 0.008 mass% or less, Pb content is 0.00002 mass% or more and 0.0003 mass% or less, and Ga is 0.002 as impurities. Electrolytic capacitor electrode formed by mass% or less, V is 0.001 mass% or less, Zr is 0.001 mass% or less, Cr is regulated to 0.001 mass% or less, and impurity elements other than the elements are regulated to 0.0005 mass% or less. Aluminum material.

  (3) The relationship between Ti content and Zn content is point A, B, C, D, E in the coordinate system with the Ti content (X axis) and Zn content (Y axis) shown in FIG. The aluminum material for electrolytic capacitor electrodes according to claim 1 or 2, which satisfies a region (including on the line) surrounded by a line connecting F and F.

  (4) The aluminum material for electrolytic capacitor electrodes as recited in any one of the aforementioned Items 1 to 3, containing B in an amount of 0.00001% by mass to 0.0002% by mass.

  (5) The manufacturing method of the electrode material for electrolytic capacitors characterized by including the process of etching in the aluminum material described in any one of the preceding clauses 1-4.

  (6) The method for producing an electrode material for an electrolytic capacitor as described in 5 above, wherein at least a part of the etching is direct current electrolytic etching.

  (7) An electrode material for an aluminum electrolytic capacitor produced by the production method according to the above item 5 or 6.

  (8) The electrode material for an aluminum electrolytic capacitor as described in 7 above, which is used as an anode material.

  (9) An aluminum electrolytic capacitor characterized in that the electrode material for an electrolytic capacitor produced by the production method according to the above item 5 or 6 is used as the electrode material.

  According to the aluminum material for electrolytic capacitor electrodes according to the invention of (1) above, the aluminum purity is 99.9% by mass or more, Ti exceeds 0.0005% by mass and 0.0025% by mass or less, Zn is 0.0004% by mass or more and 0.006% by mass or less. Contained and as impurities, Ga is 0.002% by mass or less, V is 0.001% by mass or less, Zr is 0.001% by mass or less, and Cr is 0.001% by mass or less. The capacitance can be increased by increasing the area expansion ratio.

  According to the aluminum material for electrolytic capacitor electrodes according to the invention of (2) above, the aluminum purity is 99.9% by mass or more, Ti exceeds 0.0005% by mass and 0.0025% by mass or less, Zn is 0.0004% by mass or more and 0.006% by mass or less. Si content is 0.0003 mass% or more and 0.008 mass% or less, Fe content is 0.0005 mass% or more and 0.008 mass% or less, Cu content is 0.001 mass% or more and 0.008 mass% or less, Pb content is 0.00002 mass% More than 0.0003% by mass, impurities as Ga are 0.002% by mass or less, V is 0.001% by mass or less, Zr is 0.001% by mass or less, Cr is 0.001% by mass or less, and impurities other than the above elements Since each element is regulated to 0.0005% by mass or less, etch pits can be generated with higher density and uniformity to increase the area expansion ratio and to further increase the capacitance.

  According to the aluminum material for electrolytic capacitor electrodes according to the invention of (3), the relationship between the Ti content and the Zn content is based on the Ti content (X axis) and the Zn content (Y axis) shown in FIG. In this coordinate system, the area surrounded by the line connecting points A, B, C, D, E, and F (including the area on the line) is satisfied, so that etch pits are generated with higher density and uniformity to increase the area expansion ratio. In addition, the capacitance can be increased.

  According to the aluminum material for electrolytic capacitor electrodes according to the invention of the preceding item (4), since B is contained in an amount of 0.00001% by mass or more and 0.0002% by mass or less, etch pits can be generated even more uniformly and the surface expansion rate can be increased. Further, the capacitance can be further increased.

  According to the method for manufacturing an electrode material for an electrolytic capacitor according to the invention of (5), the aluminum material described in any one of items 1 to 4 includes a step of performing etching, thereby increasing the electrostatic capacity. An electrode material for electrolytic capacitors having a capacity can be manufactured.

  According to the method for producing an electrode material for an electrolytic capacitor according to the invention of the preceding item (6), since at least a part of the etching is direct current electrolytic etching, an electrode material for an electrolytic capacitor having a larger capacitance can be produced. it can.

  Since the electrode material for an aluminum electrolytic capacitor electrode according to the invention of item (7) is manufactured by the manufacturing method according to item 5 or item 6, it can be considered to have a large capacitance.

  The electrode material for an aluminum electrolytic capacitor electrode according to the invention of (8) above can be used as an anode material having a large capacitance.

  The aluminum electrolytic capacitor according to the invention of the preceding item (9) has a large capacitance because the electrode material for an electrolytic capacitor manufactured by the manufacturing method of the preceding item 5 or 6 is used as an electrode material. You can do it.

  In the aluminum material for electrolytic capacitor electrodes according to the present invention, the significance of addition of each element and the reason for limiting the content are as follows.

[Aluminum purity]
The aluminum purity is preferably 99.9% by mass or more, and if it is less than 99.9% by mass, etch pit concentration or over-dissolution tends to occur during etching, and a large electrostatic capacity cannot be obtained. The aluminum purity is more preferably 99.96% by mass or more, and even more preferably 99.98% by mass or more.

[Ti content]
Ti has an effect of promoting the generation of etch pits, and its content is preferably more than 0.0005 mass% and 0.0025 mass% or less. When the Ti content is 0.0005% by mass or less, the effect of promoting the generation of etch pits is small, and the effect of increasing the capacitance is small. Desirably, it is 0.00065 mass% or more, and more desirably 0.0008 mass% or more. On the other hand, when the content exceeds 0.0025% by mass, local dissolution due to concentration of etch pits is likely to occur, which may cause a decrease in capacitance. Desirably, it is 0.0022 mass% or less, and more desirably 0.0018 mass% or less.

[Zn content]
Zn has the effect of promoting the progress of the etching reaction by slightly lowering the potential of the aluminum substrate, and its content is preferably 0.0004 mass% or more and 0.006 mass% or less. When the Zn content is less than 0.0004 mass%, the effect of promoting the progress of the etching reaction is small, and the effect of increasing the capacitance is small. Desirably, it is 0.0006 mass% or more. On the other hand, if the content exceeds 0.006% by mass, the etching reaction proceeds excessively, which may cause a decrease in capacitance. Desirably, it is 0.0045 mass% or less, and more desirably 0.0036 mass% or less.

[Relationship between Ti content and Zn content]
The relationship between the Ti content and the Zn content is shown in FIG. 1 in the coordinate system (Ti content mass%, Zn content mass%) with the Ti content (X axis) and the Zn content (Y axis) as coordinate axes. , Point A (0.0005 mass%, 0.0004 mass%), point B (0.0015 mass%, 0.0004 mass%), point C (0.0025 mass%, 0.0007 mass%), point D (0.0025 mass%, 0.006 mass%), point It is desirable to fill a region (including a line) surrounded by E (0.0018 mass%, 0.006 mass%) and point F (0.0005 mass%, 0.0016 mass%). This condition further promotes the effects of Ti and Zn in the etching process of the aluminum material, and contributes to an increase in capacitance.

[Ga content]
Ga, which is an impurity, increases the solubility of the aluminum substrate, and as the content increases, the local solubility becomes stronger. Therefore, when it is excessively contained, the capacitance decreases due to the concentration of etch pits. Therefore, the content is preferably regulated to 0.002% by mass or less. In particular, the content is preferably controlled to 0.0015% by mass or less, and more preferably 0.0010% by mass or less.

[V, Zr, Cr content]
When impurities such as V, Zr, and Cr are contained together with Ti, etch pits are excessively generated, which causes bond of etch pits, thus preventing an increase in capacitance. Therefore, the content of each is preferably regulated to 0.001% by mass or less. In particular, it is desirable that the amount is regulated to 0.0005% by mass or less, and the total of V, Zr, and Cr is more preferably 0.0012% by mass or less.

[Si content]
Si is an element that affects the formation of the cubic orientation of the aluminum material, and its content is preferably 0.0003 mass% or more and 0.008 mass% or less. When the Si content is less than 0.0003 mass%, the crystal grains become coarse, the cube orientation occupancy decreases, and the capacitance decreases. Desirably, the content is 0.0006% by mass or more, and more desirably 0.0008% by mass or more. On the other hand, if the Si content exceeds 0.008% by mass, the growth of the cube orientation is hindered, so that the cube orientation occupancy decreases and the capacitance decreases. Desirably, it is 0.006 mass% or less, and further 0.004 mass% or less is desirable.

[Fe content]
Fe is an element that affects the solubility of the aluminum material in the cubic orientation and etching, and its content is preferably 0.0005 mass% or more and 0.008 mass% or less. When the Fe content is less than 0.0005% by mass, the crystal grains become coarse, the cube orientation occupation ratio decreases, and the capacitance decreases. Desirably, it is 0.0008 mass% or more. On the other hand, when the content exceeds 0.008% by mass, the growth of the cube orientation is hindered, so that the cube orientation occupancy decreases, and over-dissolution occurs, causing a decrease in the surface expansion ratio, and the capacitance decreases. Desirably, it is 0.006 mass% or less, and further 0.004 mass% or less is desirable.

[Cu content]
Cu has the effect of increasing the solubility of the aluminum material, promoting the generation and growth of etch pits, and increasing the capacitance by dissolving in aluminum, so the content is 0.001% by mass or more and 0.008% by mass. % Or less is preferable. If the Cu content is less than 0.001% by mass, the effect of increasing the solubility of aluminum is small, and the contribution to the increase in capacitance is small. Desirably, it is 0.002 mass% or more, and further desirably 0.003 mass% or more. On the other hand, if the content exceeds 0.008% by mass, over-dissolution occurs, causing a reduction in the area expansion ratio, and the capacitance decreases. Desirably, it is 0.007 mass% or less, and further 0.006 mass% or less is desirable.

[Pb content]
Pb has the effect of concentrating on the foil surface during final annealing, promoting the generation of etch pits at the initial stage of etching, and increasing the capacitance, and its content is preferably 0.00002 mass% or more and 0.0003 mass% or less. When the Pb content is less than 0.00002% by mass, the effect of promoting the generation of etch pits is poor, and the generation of etch pits becomes non-uniform, and the contribution to the increase in capacitance is small. Desirably, the content is 0.00003% by mass or more, and more desirably 0.00004% by mass or more. On the other hand, if the upper limit of 0.0003% by mass is exceeded, dissolution of the aluminum material surface becomes violent and inhibits the generation of etch pits. Desirably, it is 0.0002 mass% or less, and further desirably 0.00012 mass% or less.

[B content]
B concentrates on the foil surface during the final annealing and contributes to the generation of etch pits at the beginning of etching, but if it exists in excess, the generation of etch pits at the beginning of etching becomes non-uniform and further forms a compound with Ti to cause local dissolution. Since the possibility is high, the content is preferably 0.0002% by mass or less. Desirably, it is 0.0001 mass% or less. On the other hand, the lower limit of the content is preferably 0.00001% by mass. If it is less than 0.00001% by mass, there is no problem in characteristics, but the purity of the raw material to be used has to be very high, and the production cost is remarkably high.

[Other impurity elements]
Impurity elements other than Ti, Zn, Ga, V, Zr, Cr, Si, Fe, Cu, Pb, and B are limited to 0.0005% by mass or less, respectively. It is preferable from the viewpoint of preventing overdissolution that causes a decrease.

  Moreover, the thickness of the aluminum material for electrolytic capacitor electrodes according to the present invention is not limited. Those having a thickness of 200 μm or less, referred to as foil, and those having a thickness larger than that are also included in the present invention.

  In addition, the manufacturing method of the aluminum material for electrolytic capacitor electrodes according to the present invention is not particularly limited, and is performed based on well-known methods and conditions such as ingot manufacturing, hot rolling, cold rolling, cleaning, and annealing. Just do it. Before hot rolling the ingot, a chamfering process for removing the ingot surface or a homogenization treatment may be performed. Further, intermediate annealing may be performed during the cold rolling. Further, a step of trimming the end of the aluminum material, a step of dividing the aluminum material in the width direction, or a step of simultaneously performing both in the middle of the rolling process or after the end of the rolling process may be included.

  The aluminum material for electrolytic capacitor electrodes according to the present invention is used as an electrode material for electrolytic capacitors after being etched for improving the surface expansion ratio. The etching treatment conditions are not particularly limited, but it is preferable that at least a part of the etching is direct current electrolytic etching.

  The aluminum material produced according to the present invention can be used as a cathode material or an anode material. However, the aluminum material can be used as an anode material in that it has a large effective area even when a voltage-resistant film is formed by a chemical conversion treatment after etching. Is suitable. Furthermore, among anode materials, it is suitable for medium and high pressure electrolytic capacitor electrode materials.

  Moreover, the electrolytic capacitor using this electrode material can realize a large capacitance. The type and manufacturing method of the electrolytic capacitor are not particularly limited. For example, a capacitor element in which an anode material and a cathode material each having a lead tab electrically connected thereto are wound or laminated via a separator is used for driving. The manufacturing method which impregnates electrolyte solution and uses it as an aluminum electrolytic capacitor can be mentioned.

  Specific examples of the present invention will be described below.

  In producing the aluminum material, first, aluminum ingots having the compositions shown in Table 1, Table 2 and Table 3 were prepared using a small book mold. These ingots were subjected to homogenization treatment, chamfering, hot rolling, cold rolling, and intermediate annealing in the middle of cold rolling by a well-known ordinary method to obtain a foil having a thickness of 110 μm. Thereafter, after degreasing and cleaning, annealing was performed in an inert gas at 520 ° C. for 5 hours.

Next, the electrostatic capacity of each aluminum material was measured by the following method. First, it was immersed in an aqueous solution containing 1 mol / l hydrochloric acid and 3.5 mol / l sulfuric acid at a liquid temperature of 75 ° C. and then subjected to direct current electrolytic etching at a current density of 0.2 A / cm ² . The aluminum material after the direct current electrolytic etching treatment was further immersed in a hydrochloric acid-sulfuric acid mixed solution having the above composition at 90 ° C. for 360 seconds, and a chemical etching treatment for increasing the diameter of the etching pit formed by the direct current electrolytic etching treatment was performed.

  The etched aluminum material was subjected to chemical conversion treatment at a chemical conversion voltage of 270 V in accordance with EIAJ standards, and the capacitance was measured.

  The measured capacitance of each aluminum material is shown in Table 1, Table 2, and Table 3 as relative capacitance values when the capacitance of Comparative Example 1 is 100.

  As the results of Tables 1, 2 and 3 show, it was confirmed that Nos. 1 to 37, which are examples of the present invention, have higher capacitance than Comparative Examples No. 1 to 10.

It is a graph which shows the relationship between Ti content and Zn content.

Claims (7)

Aluminum purity is 99.9% by mass or more, Ti is over 0.0005% by mass and 0.0025% by mass or less, Zn is 0.0004% by mass to 0.006% by mass , B is 0.00001% by mass to 0.0002% by mass, and Si is 0.0003% by mass. Containing 0.0005 mass% or more and 0.008 mass% or less of Fe, 0.001 mass% or more and 0.008 mass% or less of Cu, 0.00002 mass% or more and 0.0003 mass% or less of Pb , and Ga as an impurity, 0.002 mass % % Or less, V is 0.001 mass% or less, Zr is 0.001 mass% or less, Cr is regulated to 0.001 mass% or less , and impurity elements other than the above elements are regulated to 0.0005 mass% or less, respectively . Aluminum material. The relationship between the Ti content and the Zn content is expressed by points A, B, C, D, E, and F in the coordinate system with the Ti content (X axis) and the Zn content (Y axis) shown in FIG. The aluminum material for electrolytic capacitor electrodes according to claim 1 , which satisfies a region (including on the line) surrounded by connecting lines.
The manufacturing method of the electrode material for electrolytic capacitors characterized by including the process of etching in the aluminum material described in Claim 1 or 2. The method for producing an electrode material for an electrolytic capacitor according to claim 3, wherein at least a part of the etching is direct current electrolytic etching. The electrode material for aluminum electrolytic capacitors manufactured by the manufacturing method of Claim 3 or Claim 4. The electrode material for an aluminum electrolytic capacitor according to claim 5, which is used as an anode material. An aluminum electrolytic capacitor characterized in that an electrode material for an electrolytic capacitor produced by the production method according to claim 3 or 4 is used as an electrode material.

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