阅读说明：本技术 高压电解电容器阳极用铝轧制材料及其制造方法 (Rolled aluminum material for high-voltage electrolytic capacitor anode and method for producing same ) 是由 宗宫和久 山之井智明 于 2019-10-09 设计创作，主要内容包括：本发明的目的是提供一种能够增大静电容量的高压电解电容器阳极用铝轧制材料。高压电解电容器阳极用铝轧制材料,铝纯度为99.9％以上,含有Fe：5～30ppm、Si：5～30ppm、Cu：35～80ppm,满足35≤C-(Cu)+5C-(Ag)≤80ppm(其中C-(Cu)表示Cu含量,C-(Ag)表示Ag含量)的关系,并且含有Mn：0.5～20ppm、Cr：0.5～15ppm、Mg：0.2～10ppm、Zn：0.5～20ppm、Ga：0.5～25ppm、Ti：0.2～5ppm。(The invention aims to provide an aluminum rolled material for a high-voltage electrolytic capacitor anode, which can increase the electrostatic capacity. An aluminum rolled material for a high-voltage electrolytic capacitor anode, having an aluminum purity of 99.9% or more, containing Fe: 5-30 ppm, Si: 5-30 ppm, Cu: 35-80 ppm, and C is more than or equal to 35 Cu +5C Ag Less than or equal to 80ppm (wherein C) Cu Represents the Cu content, C Ag Representing Ag content), and contains Mn: 0.5-20 ppm, Cr: 0.5-15 ppm, Mg: 0.2-10 ppm, Zn: 0.5 to 20ppm, Ga: 0.5 to 25ppm, Ti: 0.2 to 5 ppm.)

1. An aluminum rolled material for anodes of high-voltage electrolytic capacitors, characterized in that,

the aluminum has a purity of 99.9% or more, and contains Fe: 5-30 ppm, Si: 5-30 ppm, Cu: 35-80 ppm, and C is more than or equal to 35_Cu+5C_AgIn a relation of 80ppm or less, wherein C_CuRepresents the Cu content, C_AgRepresents an Ag content, and contains Mn: 0.5-10 ppm, Cr: 0.5-15 ppm, Mg: 0.2-10 ppm, Zn: 0.5 to 20ppm, Ga: 0.5 to 25ppm, Ti: 0.2 to 5 ppm.

2. The rolled aluminum material for high-voltage electrolytic capacitor anodes as claimed in claim 1, which comprises a metal selected from the group consisting of V: 0.2 to 5ppm, Zr: 0.2-5 ppm, B: 0.2 to 5 ppm.

3. The rolled aluminum material for anodes of high-voltage electrolytic capacitors as claimed in claim 2, which contains a compound selected from the group consisting of Pb: 0.2 to 3ppm, Bi: 0.2 to 3ppm, Sn: 0.2 to 10 ppm.

4. The rolled aluminum material for high-voltage electrolytic capacitor anodes as claimed in claim 3, which contains Ag: more than 0.2-9 ppm and P: at least one of 0.2 to 10 ppm.

5. A method for producing an aluminum rolled material for high-voltage electrolytic capacitor electrodes, comprising the steps of: an aluminum alloy ingot having the composition as set forth in any one of claims 1 to 4, wherein before or after the subsequent surface cutting, homogenization treatment is performed at a temperature of 500 ℃ or higher and 620 ℃ or lower for a time of 1 hour or longer and 50 hours or shorter, after cooling in this state or reheating at a temperature of 450 ℃ or higher and 560 ℃ or lower for a time of 5 minutes or longer and 20 hours or shorter, hot rolling is started, hot rolling is performed in a plurality of rolling passes at a reduction ratio of 95% or higher and 99.5% or lower, cold rolling is continued, after intermediate annealing, cold rolling is performed at 5% or higher and 30% or lower, and heat treatment is performed at a temperature of 400 ℃ or higher and 580 ℃ or lower for a time of 1 hour or longer and 20 hours or shorter.

Technical Field

The present invention relates to an aluminum rolled material for a high-voltage electrolytic capacitor anode and a method for producing the same.

Background

In general, an aluminum rolled material used as an anode material for an aluminum electrolytic capacitor is generally subjected to electrochemical or chemical etching treatment in order to increase the effective area and increase the capacitance per unit area.

However, sufficient capacitance cannot be obtained only by etching the foil. Therefore, in particular, in high-pressure applications, there have been proposed a method of controlling the conditions of intermediate annealing, cold rolling and final annealing in order to form an aggregate structure having a large number of cubic orientations and improve the etching characteristics of the foil, a method of adding various trace elements from the surface of the alloy composition of the foil in order to further uniformly distribute pits at a high density, and the like in the final annealing step after foil rolling.

For such applications, for example, patent document 1 discloses a production method in which the purity of aluminum is 99.98% or more, Si, Fe, Cu, and Mg are contained, and the cubic orientation occupancy of an aluminum rolled material is improved by controlling the production conditions, and patent document 2 discloses an alloy foil in which the purity of aluminum is 99.98% or more, Si, Fe, Cu, Mn, Cr, Mg, Zn, Ga, and Ti are contained, one or more of V, Zr, and B are contained, and one or more of Pb, Bi, and Sn are contained.

Prior art documents

Patent document 1: CN 1807673A

Patent document 2: CN 104616897B

Disclosure of Invention

Problems to be solved by the invention

However, the aluminum rolled material containing the above-mentioned trace elements added thereto and controlled production conditions does not sufficiently satisfy the requirement of the electrolytic capacitor for high capacitance.

In view of the background, an object of the present invention is to provide an aluminum rolled material for an electrolytic capacitor electrode, which can increase the capacitance, and a method for producing the same.

Means for solving the problems

As a result of earnest study to solve the above problems, the present inventors have found that Ag coexists in an alloy containing Fe, Si, Cu, Mn, Mg, Cr, Zn, Ga, and Ti in a certain relationship with Cu in the composition of an aluminum rolled material, and thereby the area enlargement rate by etching can be increased, and further, addition of various trace elements can synergistically act to obtain an aluminum rolled material having a high electrostatic capacity. That is, the invention of the present application is as follows.

(1) An aluminum rolled material for anodes of high-voltage electrolytic capacitors, characterized in that the aluminum has a purity of 99.9% or more, and contains Fe: 5-30 ppm, Si: 5-30 ppm, Cu: 35-80 ppm, and C is more than or equal to 35_Cu+5C_AgLess than or equal to 80ppm (wherein C)_CuRepresents the Cu content, C_AgRepresenting Ag content), and contains Mn: 0.5-10 ppm, Cr:0.5～15ppm、Mg：0.2～10ppm、Zn：0.5～20ppm、Ga：0.5～25ppm、Ti：0.2～5ppm。

(2) the rolled aluminum material for high-voltage electrolytic capacitor anodes according to the above (1), comprising a metal selected from the group consisting of V: 0.2 to 5ppm, Zr: 0.2-5 ppm, B: 0.2 to 5 ppm.

(3) The rolled aluminum material for high-voltage electrolytic capacitor anodes according to the above (2), which contains a metal selected from the group consisting of Pb: 0.2 to 3ppm, Bi: 0.2 to 3ppm, Sn: 0.2 to 10 ppm.

(4) The rolled aluminum material for high-voltage electrolytic capacitor anodes according to the above (3), which contains Ag: more than 0.2-9 ppm and P: at least one of 0.2 to 10 ppm.

(5) A method for producing an aluminum rolled material for high-voltage electrolytic capacitor electrodes, comprising the steps of: an aluminum alloy ingot having a composition as set forth in any one of (1) to (4) above, wherein before or after the subsequent surface cutting, homogenization treatment is performed at a temperature of 500 ℃ to 620 ℃ inclusive and for a time of 1 hour to 40 hours inclusive, after cooling in this state or after reheating at a temperature of 450 ℃ to 560 ℃ inclusive for 5 minutes to 20 hours inclusive, hot rolling is started, hot rolling is performed in a plurality of rolling passes at a reduction ratio of 95% to 99.5% inclusive, cold rolling is continued, and after intermediate annealing, cold rolling of 5% to 30% inclusive and heat treatment at a temperature of 400 ℃ to 580 ℃ inclusive for 1 hour to 20 hours inclusive are performed.

ADVANTAGEOUS EFFECTS OF INVENTION

The aluminum alloy foil for electrolytic capacitor electrodes according to the present invention can increase the density of etching pits, increase the depth thereof, and uniformly disperse the pits, and can obtain a very large area enlargement ratio by etching treatment. Therefore, an aluminum rolled material for an electrolytic capacitor electrode having a large capacitance and excellent electrical characteristics can be provided.

Detailed Description

The aluminum alloy foil for electrolytic capacitor electrodes of the present invention is characterized in that the aluminum purity is 99.9% or moreAnd, contains Fe: 5-30 ppm, Si: 5-30 ppm, Cu: 35-80 ppm, and C is more than or equal to 35_Cu+5C_AgLess than or equal to 80ppm (wherein C)_CuRepresents the Cu content, C_AgRepresenting Ag content), and contains Mn: 0.5-10 ppm, Cr: 0.5-15 ppm, Mg: 0.2-10 ppm, Zn: 0.5 to 20ppm, Ga: 0.5 to 25ppm, Ti: 0.2 to 5 ppm.

Hereinafter, the present invention will be described in detail.

The aluminum alloy foil according to the present invention is used for forming an aluminum rolled material for an electrolytic capacitor anode, which can increase the electrostatic capacity.

(purity of aluminum)

The reason why the aluminum purity of the rolled aluminum material for electrolytic capacitor electrodes according to the present invention needs to be 99.9% or more is that if the purity is less than 99.9%, the growth of pits is inhibited by the presence of many impurities during etching, and even if trace elements within the range of the present invention are present, uniform and deep pits cannot be formed, and thus an aluminum rolled material having a high electrostatic capacity cannot be obtained. The aluminum purity is preferably 99.98% or more.

The trace elements Fe, Si, Cu, Mn, Cr, Mg, Zn, Ga, and Ti contained in the foil composition contribute to the improvement of the etching characteristics of the foil, respectively, as described below, and by further containing a metal element selected from the group consisting of V: 0.2 to 10ppm, Zr: 0.2-10 ppm, B: 0.2 to 20ppm of at least one compound selected from the group consisting of Pb: 0.2 to 5ppm, Bi: 0.2 to 5ppm, Sn: 0.2 to 10ppm, respectively, can obtain synergistic effects corresponding to their respective effects.

(Fe, Si content)

Fe. Si easily forms a compound with Al in the Al matrix, and the pits can be uniformly distributed by controlling the dispersion state of these elements. However, if the content is too large, it becomes a cause of excessive dissolution during etching, resulting in a decrease in electrostatic capacity. Therefore, the Fe content should be 5 to 30ppm, preferably 12ppm at the lower limit and 20ppm at the upper limit. The Si content is required to be 5 to 30ppm, preferably 12ppm at the lower limit and 25ppm at the upper limit. In the case of performing the etching of the trench type, the electrostatic capacity can be increased if the area occupancy (hereinafter referred to as cubic orientation occupancy) of crystal grains having {100} plane orientation in the surface of the aluminum rolled material is 95% or more, and if the Fe and Si contents are within the above range, 95% or more can be achieved by controlling the process conditions.

(Cu content)

Cu is dissolved in the Al matrix, and thereby increases the solubility of the foil, promotes the growth of pits, forms deep pits, and increases the electrostatic capacity. If the Cu content is less than 35ppm, the above effect is poor, and if it exceeds 80ppm, the local solubility is increased, which may prevent uniform distribution of the etching pits. Therefore, the Cu content needs to be 35 to 80ppm, preferably 40ppm at the lower limit and 75ppm at the upper limit.

(Ag content)

There is a correlation between Cu and Ag that shows an interaction for controlling the solubility of the foil, forming fine etching pits, and obtaining a high capacitance. Therefore, the range is limited to the following range.

35≤C_Cu+5C_Ag≤80ppm

Wherein, C_CuRepresents the Cu content, C_AgRepresents the Ag content.

However, if the Ag content is increased, the pits become excessively fine, and the pits are detached due to the combination thereof, thereby decreasing the electrostatic capacity. Therefore, the Ag content should be 0.2 to 9ppm, and the preferable lower limit and upper limit of the Ag content are 0.3ppm and 8ppm, respectively.

(Mn content)

Mn easily forms a compound with Al in an Al matrix, and by controlling the dispersion state of this element, the solubility of the foil can be increased, the growth of pits can be promoted, deep pits can be formed, and the electrostatic capacity can be increased. If the Mn content is less than 0.5ppm, the above effect is poor, and if it exceeds 10ppm, the local solubility is increased, which may prevent uniform distribution of the etch pits. Therefore, the Mn content should be 0.5 to 10ppm, preferably 1ppm at the lower limit and 8ppm at the upper limit.

(Cr content)

Cr is likely to form a compound with Al in an Al matrix, and by controlling the dispersion state of this element, the solubility of the foil can be increased, the growth of pits can be promoted, deep pits can be formed, and the electrostatic capacity can be increased. If the Cr content is less than 0.5ppm, the above effect is poor, and if it exceeds 15ppm, the local solubility is increased, which may prevent uniform distribution of pits. Therefore, the Cr content should be 0.5 to 15ppm, preferably 1ppm at the lower limit and 12ppm at the upper limit.

(Mg content)

Mg is an element necessary for highly dense and uniform distribution of etching pits during etching. That is, the unevenness usually present on the surface of the foil at the initial stage of etching and the uneven local dissolution pits due to the deposits such as oil and roll coating material or the deterioration products thereof cause uneven density (density) of the pits, and in a serious case, the surface dissolves like craters. This unevenness also remains after the etching is completed, and causes a decrease in capacitance. Therefore, in order to prevent such a problem, the inventors of the present invention have made extensive studies to control the cause of the unevenness of the etching pits present on the surface, and as a result, have found that Mg has an effect of removing the local portions of the etching pits and forming the etching pits at a high density. On the other hand, if it exceeds 10ppm, the cubic orientation occupancy after the final annealing is lowered, and a foil with high electrostatic capacity cannot be obtained. Therefore, the Mg content is required to be 0.2 to 10 ppm. The lower limit of the Mg content is preferably 1ppm, and the upper limit thereof is preferably 8 ppm.

(Zn content)

Zn is an element that slightly lowers the substrate potential by being dissolved in an Al substrate, and the presence of a trace amount can increase the solubility of the foil, promote the growth and expansion of pits, and increase the electrostatic capacity. If the Zn content is less than 0.5ppm, the above effect is poor, and if it exceeds 20ppm, the local solubility becomes strong, which may prevent uniform distribution of pits. Therefore, the Zn content should be 0.5 to 20ppm, preferably 1ppm at the lower limit and 18ppm at the upper limit.

(Ga content)

While Ga, if present in excess, is likely to segregate at grain boundaries or subgrain boundaries, and is an element that, when present alone, causes uneven distribution of pits, Ge has the effect of improving the uniform dispersibility of pits in the presence of Mg, because Mg reduces the size of subgrain boundaries. If the Ga content is less than 0.5ppm, the above effect is poor, and if it exceeds 25ppm, the local solubility becomes strong, which may prevent uniform distribution of pits. Therefore, the Ga content needs to be 0.5 to 25ppm, preferably 1ppm at the lower limit and 20ppm at the upper limit.

(Ti content)

The small amount of Ti dissolved in the Al matrix increases the solubility of the foil, promotes the growth and enlargement of the etching pits, and increases the electrostatic capacity. However, if the content is too large, segregation tends to occur in the grain boundary, which causes uneven etching pits, and therefore, it is necessary to control the ratio of Ti: 0.2 to 5ppm, preferably 1ppm at the lower limit and 3ppm at the upper limit.

(V, Zr, B content)

B. V, Zr the generation of etching pits is promoted and the capacitance is increased. However, since segregation is likely to occur if the content is increased, which causes unevenness of etching pits, it is necessary to control the ratio of V: 0.2 to 5ppm, Zr: 0.2-5 ppm, B: 0.2 to 5 ppm.

(Pb, Bi, Sn content)

Pb, Bi, and Sn suppress local solubility at the initial stage of etching, and contribute to uniform distribution of etching pits. If the Pb or Bi content is less than 0.2ppm, the above effect is poor, and if it exceeds 3ppm, surface dissolution may occur. Therefore, the Pb and Bi contents should be 0.2 to 3 ppm. Sn has the same effect, but has a low influence on surface dissolution, so the upper limit is 10 ppm. Therefore, the Sn content needs to be 0.2 to 10 ppm. The preferable lower limit to the preferable upper limit are Pb: 0.2 to 2ppm, Bi: 0.2 to 2ppm, Sn: 0.5 to 8 ppm.

(P content)

P suppresses local solubility at the initial stage of etching and contributes to uniform distribution of etching pits. If the P content is less than 0.2ppm, the above effect is poor, and if it exceeds 10ppm, surface dissolution may occur. Therefore, the P content is required to be 0.2 to 10 ppm.

Next, the following method is more preferable for the production method of the present invention. For example, there is a method in which an aluminum alloy ingot produced by a semi-continuous casting method is subjected to a homogenization treatment at a temperature of 500 ℃ to 620 ℃ inclusive and for a time of 1 hour to 50 hours inclusive before or after surface cutting to be performed subsequently, and after cooling in this state or after reheating at a temperature of 450 ℃ to 560 ℃ inclusive and holding for 5 minutes to 20 hours inclusive, hot rolling is started, hot rolling is performed in a plurality of rolling passes at a reduction ratio of 95% to 99.5% inclusive, and then cold rolling is continued. More preferable ranges of the homogenization treatment are a temperature of 520 ℃ to 600 ℃ inclusive, and 3 hours to 30 hours inclusive. More preferable ranges of the hot rolling start temperature and the holding time are 480 ℃ to 520 ℃ inclusive, and 5 minutes to 15 hours inclusive.

In addition, in the final annealing step after the cold rolling, it is necessary to form an aggregate structure having many cubic orientations by recrystallization. Therefore, it is effective to perform annealing at a temperature of 400 ℃ to 580 ℃ for 1 hour to 20 hours. If the temperature is lower than 400 ℃, the growth of cubic oriented grains is insufficient, resulting in non-uniformity of pit-like pits and a decrease in electrostatic capacity. In addition, in the temperature range of more than 580 ℃, adhesion of the material and coarsening of crystal grains occur, which leads to a decrease in the strength of the material and a decrease in the pit density. The more preferable range of the final annealing temperature is 450 ℃ or more and 560 ℃ or less. The time is more preferably 2 hours or more and 18 hours or less.

In addition, performing at least one intermediate annealing and subsequent cold rolling in the cold rolling process can contribute to an increase in cubic orientation occupancy after the final annealing. The temperature of the intermediate annealing in this case may be 220 ℃ to 300 ℃ and the time may be 1 hour to 30 hours. When the intermediate annealing is performed, the cold rolling reduction until the final cold rolling may be 5% or more and 30% or less. A more preferable range of the cold rolling reduction after the intermediate annealing is 10% or more and 25% or less.

Examples

The present invention will be described below with reference to examples. The scope of the present invention is not limited to the embodiments described herein, and can be implemented with appropriate modifications within the spirit of the present invention, and all of them are included in the technical scope of the present invention.

First, aluminum ingots having various compositions shown in Table 1 were produced by a semi-continuous casting method, and ingots having a thickness of 400mm were subjected to homogenization treatment and hot rolling under the conditions shown in Table 2. Subsequently, cold rolling, intermediate annealing, and cold rolling were performed to obtain foils having thicknesses shown in table 3, and then final annealing was performed.

Next, the obtained rolled aluminum materials were subjected to etching and chemical conversion treatment under the following conditions, and then the electrostatic capacities were measured. The results are shown in Table 3 (comparative No.7) as relative comparisons in which the electrostatic capacity of the comparative foil is 100% and the folding strength is 100% for each of the comparative foils under different etching conditions.

[ etching conditions ]

The primary etching solution uses 5% HCl + 25% H₂SO₄The aqueous solution of (2) was conducted at a temperature of 75 ℃ and a current density of 40A/dm by direct current²And an etching treatment for 90 seconds. Then, the second etching was performed by immersion etching using a 5% hydrochloric acid aqueous solution at a temperature of 90 ℃ for 10 minutes.

[ formation conditions ]

The aluminum material subjected to the etching treatment was subjected to chemical conversion treatment in an aqueous solution of 10% boric acid bath and 0.09% ammonium borate at a temperature of 85 ℃ and a chemical conversion voltage of 270V.

[ conditions for measuring Electrostatic capacity ]

Using an LCR tester at room temperature in 8% ammonium borate solution, the frequency: the electrostatic capacity was measured at 120 Hz.

[ measurement conditions for folding Strength ]

Based on EIAJ RC-2364A

The higher the value of the electrostatic capacity, the better. In the present invention, an improvement of 2% or more can be judged as the observation of the effectiveness. On the other hand, when the residual core formed of the pit-like etching pits extending from the foil surface is appropriate, the value of the folding endurance strength is close to that of the comparative material, and when the etching is not sufficiently performed, the value becomes a high value. However, if the etching depth is too high, the effect is not obtained, and the capacitance is rather lowered to the extent that the length of the pit-like etching pit is short. In addition, when the etching is excessively performed, the etching pits in the form of pits extending from the foil surface are integrated in the foil center portion, resulting in a significant decrease in the folding endurance strength. An appropriate value of the folding endurance is 98% or more in the present example, and it is judged that the same effect is obtained even if the folding endurance is increased to 102% or more.

The results are shown in table 3. As is clear from the results in table 3, the present invention examples in which the alloy containing Fe, Si, Cu, Mn, Cr, Mg, Zn, Ga, and Ti in the range of the present invention coexists Ag with a certain correlation with Cu, further contains one or more of V, Zr, and B, further contains one or more of Pb, Bi, and Sn, and further contains P have improved etching characteristics and increased electrostatic capacity as compared with the comparative examples out of the range of the present invention.

Industrial applicability

The aluminum alloy foil for electrolytic capacitor electrodes according to the present invention can increase the density of etching pits, increase the depth thereof, uniformly disperse the pits, and obtain a very large area enlargement ratio by etching treatment. Therefore, the rolled aluminum material can be used for forming an electrolytic capacitor electrode aluminum rolled material having a large capacitance and excellent electrical characteristics.

TABLE 1 compositions

TABLE 2 procedure

Table 3 evaluation results