Electrode foil for electrolytic capacitor, electrolytic capacitor, and method for manufacturing electrode foil for electrolytic capacitor

Abstract

An electrode foil for an electrolytic capacitor is provided with a metal foil containing a valve metal. The metal foil has a core portion and a porous portion continuous with the core portion. The porous portion has a main surface of a metal foil, and the main surface has a glossiness G1 of 10 or more at an incidence angle of 20 degrees.

Description

Technical Field

[0001] The present disclosure relates to an electrode foil for an electrolytic capacitor, an electrolytic capacitor, and a method for manufacturing the electrode foil for an electrolytic capacitor. Background Art

[0002] The electrode foil of the electrolytic capacitor contains a valve-acting metal and has a porous portion and a core portion continuous with the porous portion. The porous portion can provide an electrode foil with a large surface area, thereby increasing the capacity of the electrolytic capacitor.

[0003] Patent Document 1 proposes an electrode foil for an aluminum electrolytic capacitor, characterized in that an aluminum foil that has been subjected to a surface expansion process by etching is compressed in the foil thickness direction to increase the surface area per unit volume compared to before compression.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 11-26320 Summary of the invention

[0007] -Problems that the invention aims to solve-

[0008] Research on the porous portion (etching layer) is still insufficient, and further improvement in the performance of electrolytic capacitors is required.

[0009] -Methods used to solve the problem-

[0010] One embodiment of the present disclosure relates to an electrode foil for an electrolytic capacitor, comprising: a metal foil including a valve-acting metal, the metal foil having a core and a porous portion continuous with the core, the porous portion having a main surface of the metal foil, and a glossiness G1 of the main surface at an incident angle of 20 degrees being greater than 10.

[0011] Another embodiment of the present disclosure relates to an electrolytic capacitor, which includes a capacitor element, wherein the capacitor element includes a winding body and an electrolyte, wherein the winding body is formed by winding an anode foil, a cathode foil and a separator arranged between the anode foil and the cathode foil, and the anode foil includes the above-mentioned electrode foil and a dielectric layer, and the dielectric layer covers the metal skeleton of the porous part constituting the above-mentioned electrode foil.

[0012] Another embodiment of the present disclosure relates to a method for manufacturing an electrode foil for an electrolytic capacitor, the manufacturing method comprising: an etching step, etching a sheet containing a valve-acting metal to form a porous portion on two main surfaces of the sheet; and compressing the etched sheet along the thickness direction to form the main surface having a glossiness G1 of 10 or more at an incident angle of 20 degrees.

[0013] -Effects of the Invention-

[0014] According to the present disclosure, it is possible to obtain an electrolytic capacitor having high reliability and large capacity.

[0015] The novel features of the present invention are set forth in the appended claims, but the present invention, both as to structure and content, together with other objects and features of the present invention, will be better understood from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional view schematically showing an example of an electrode foil for an electrolytic capacitor according to an embodiment of the present disclosure.

[0017] Figure 2 This is a diagram schematically showing an example of a compression step in the method for producing an electrode foil for an electrolytic capacitor according to an embodiment of the present disclosure.

[0018] Figure 3 It is a cross-sectional view schematically showing an example of an electrolytic capacitor according to an embodiment of the present disclosure.

[0019] Figure 4 It is schematically shown Figure 3 A three-dimensional diagram of the structure of the winding body. DETAILED DESCRIPTION

[0020] The following examples are given to illustrate the embodiments of the present disclosure, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes exemplified, but other numerical values ​​and materials can also be applied as long as the effects of the present disclosure can be obtained. In this specification, a description such as "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be renamed as "above numerical value A and below numerical value B". In the following description, when a lower limit and an upper limit are exemplified for numerical values ​​of specific physical properties, conditions, etc., as long as the lower limit does not become above the upper limit, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined. When multiple materials are exemplified, one of them can be selected and used alone, or two or more can be combined and used.

[0021] In addition, the present disclosure includes a combination of matters recorded in two or more claims arbitrarily selected from a plurality of claims recorded in the appended claims. In other words, matters recorded in two or more claims arbitrarily selected from a plurality of claims recorded in the appended claims can be combined as long as no technical contradiction occurs.

[0022] (Electrode foil for electrolytic capacitors)

[0023] The electrode foil for electrolytic capacitors according to the embodiment of the present disclosure comprises a metal foil containing a valve metal. The metal foil comprises a core portion and a porous portion continuous with the core portion. The porous portion comprises a main surface of the metal foil. The glossiness G1 (hereinafter also referred to as “glossiness G2”) of the main surface at an incident angle of 20 degrees is S (20°)".) is above 10.

[0024] The porous part contains a plurality of pores (pits). For high capacity, the surface area of ​​the foil can be increased by increasing the pit density and the thickness of the porous part. However, when the pit density and the thickness of the porous part are increased, the strength of the electrode foil is reduced, and cracks or foil breakage may occur in the electrode foil during the manufacturing process of the electrolytic capacitor. The reduction in the strength of the electrode foil is caused by the reduction in the strength of the surface layer of the porous part. In particular, when the pit density and the thickness of the porous part are large, the reduction in the strength of the surface layer becomes significant.

[0025] The factors that reduce the strength of the surface layer of the porous portion are presumed to be the following (a) to (c). (a) During electrolytic etching, the etching solution contacts the surface of the metal foil, so that the surface layer is prone to deterioration. (b) The stress generated when the metal foil is wound during the manufacturing process of the electrolytic capacitor is likely to increase on the surface layer of the metal foil. This stress increases, for example, when the diameter of the roller that winds the metal foil is small. In addition, the stress increases on the outer peripheral side compared to the inner peripheral side of the wound metal foil. (c) Long strips of valve-acting metal used in the raw materials containing the metal foil (such as Al raw foil) are generally rolled foils with rolling marks, and rolling marks are likely to remain on the surface layer of the porous portion even after etching.

[0026] On the other hand, by compressing the etched foil, the strength of the surface layer can be greatly improved, and in this case, the glossiness G1 can be greatly increased. There is a tendency that the glossiness G1 increases as the thickness reduction rate during compression increases. In addition, by adjusting the etching conditions (such as the amount of melting on the sheet surface) to suppress the degradation of the surface layer during etching, the decrease in the strength of the surface layer can be suppressed to a certain extent, and in this case, the glossiness G1 increases to a certain extent.

[0027] By compressing the etching foil, the strength of the surface layer is easily greatly improved, and it is easy to obtain a glossiness G1 of 10 or more. When the glossiness G1 is 10 or more, the decrease in the strength of the surface layer when the pit density and the thickness of the porous portion are increased is suppressed, and the tensile strength of the electrode foil is improved. In addition, the capacity per unit volume is fully improved. By using this electrode foil, a large-capacity electrolytic capacitor with excellent reliability can be obtained. In addition, the retention of the electrolyte in the pores of the porous portion is improved, and the contact between the dielectric layer and the electrolyte is improved.

[0028] From the viewpoint of suppressing the decrease in strength of the surface layer and improving the capacity per unit volume, the glossiness G1 is preferably 20 or more, more preferably 40 or more. From the viewpoint of improving the electrostatic capacitance, the glossiness G1 is preferably 140 or less, more preferably 120 or less.

[0029] Glossiness G S (20°) is determined in accordance with JIS Z 8741:1997 (the measurement method of “20° specular gloss” shown in “Method 5” in “Types of specular gloss measurement methods” in Table 1).

[0030] For the measurement of glossiness, a handheld gloss meter "PG-IIM" manufactured by Nippon Denshoku Industries Co., Ltd. can be used. When observing a long strip (strip-shaped) metal foil from the normal direction of its main surface, light is incident in parallel with the longitudinal direction (rolling direction) of the metal foil (within the range of 15° to -15° relative to the longitudinal direction) to measure the glossiness. This can reduce the influence of light scattering caused by the rolling marks of the metal foil.

[0031] From the viewpoint of suppressing the decrease in strength of the surface layer and improving the capacity per unit volume, the glossiness G at an incident angle of 60 degrees is S (60°) is preferably 55 or more, more preferably 60 or more. Similarly, the glossiness G at an incident angle of 85 degrees is S (85°) is preferably 82 or more, and more preferably 85 or more. From the viewpoint of improving electrostatic capacitance, the glossiness G S (60°) is preferably 180 or less. Similarly, the glossiness G S (85°) is preferably 180 or less.

[0032] In addition, the gloss G S (60°) and glossiness G S (85°) is determined based on the measurement method of “60 degree specular gloss” shown in “Method 3” in “Types of specular gloss measurement methods” of Table 1 of the JIS standard and the measurement method of “85 degree specular gloss” shown in “Method 1”.

[0033] The porous part has a thickness T, and has an inner layer region on the core side and a surface region on the opposite side to the core. In addition, the so-called surface region refers to a region where the distance from the outer surface of the porous part is less than T / 4 when the porous part has a thickness T (μm). The so-called inner layer region refers to a region where the distance from the boundary between the porous part and the core is less than T / 4. When the glossiness G1 is 10 or more, the average diameter D1 (nm) of the pores in the surface region is easily smaller than the average diameter D2 (nm) of the pores in the inner region. In addition, in this specification, when simply referred to as "diameter", it means "diameter".

[0034] From the viewpoint of suppressing the reduction in strength of the surface layer and increasing the capacity per unit volume, D1 / D2 is preferably less than 0.98, more preferably less than 0.95, and may be less than 0.9. From the viewpoint of improving electrostatic capacitance, the ratio of D1 to D2, i.e., D1 / D2, is preferably greater than 0.5, more preferably greater than 0.55, may be greater than 0.6, and may be greater than 0.7. The range of D1 / D2 may also be a range formed by arbitrarily combining the above-mentioned upper and lower limits, but for example, it is preferably greater than 0.5 and less than 0.98, and more preferably greater than 0.55 and less than 0.95. When the glossiness G1 is greater than 10, D1 / D2 is easily adjusted to less than 0.98.

[0035] The above-mentioned D1 and D2 can be obtained as follows.

[0036] (i) A cross-sectional image of the electrode foil is obtained by scanning electron microscopy (SEM). Using this image, the thickness of the porous portion is measured at any 10 points, and the average value thereof is calculated as the thickness T of the porous portion.

[0037] (ii) The distance from the outer surface of the porous portion to Figure 1 The area with a distance T / 4 or less from the surface S1 in the figure is defined as the surface area.

[0038] (iii) A cross-sectional image of the surface region is obtained, and the image is binarized to distinguish between a metal skeleton region constituting the surface region and a pore (pit) region outside the metal skeleton region.

[0039] (iv) A point in the pore region of the surface layer region is randomly selected, a line segment is drawn that passes through the point and crosses the pore region, and the length of the line segment when the length of the line segment is the shortest is measured. This measurement is performed on 20 random points in the pore region of the surface layer region, and the average of the measured values ​​is calculated as the average diameter D1 of the pores in the surface layer region.

[0040] (v) The distance from the boundary between the porous part and the core part ( Figure 1 The region where the distance from the surface B) in the inner layer region is T / 4 or less is defined as the inner layer region. The average diameter D2 of the pores in the inner layer region is also determined in the same manner as in (iii) and (iv) above.

[0041] When the glossiness G1 is 10 or more, the porosity P1 of the surface region is apt to be smaller than the porosity P2 of the inner region. From the viewpoint of suppressing the reduction in strength of the surface layer and improving the capacity per unit volume, P1 / P2 is preferably 0.95 or less, more preferably 0.92 or less, and may also be 0.85 or less. From the viewpoint of improving electrostatic capacitance, the ratio of P1 to P2, i.e., P1 / P2, is preferably 0.5 or more, more preferably 0.55 or more, and may be 0.6 or more, or 0.7 or more. The range of P1 / P2 may also be a range formed by arbitrarily combining the above-mentioned upper and lower limits, but, for example, it is preferably 0.5 or more and 0.95 or less, and more preferably 0.55 or more and 0.92 or less. When the glossiness G1 is 10 or more, P1 / P2 is easily adjusted to 0.95 or less.

[0042] Using the cross-sectional image of the surface region after binarization processing in (iii) obtained in the process of calculating P1, the area S0 of the entire area of ​​the image and the area S1 of the region occupied by the pores in the image are measured, and (S1 / S0)×100 is calculated to obtain the porosity P1 of the surface region. The porosity P2 of the inner region is also obtained in the same manner as above.

[0043] The surface roughness Ra of the metal foil (roughness of the outer surface of the porous portion) is preferably 1.5 μm or less, more preferably 0.1 μm or more and 1.5 μm or less, and may be 0.5 μm or more and 1.5 μm or less. The surface roughness Ra of the metal foil means the arithmetic mean roughness, and the arithmetic mean roughness Ra is obtained based on JIS B 0601:2001.

[0044] When the surface roughness Ra of the metal foil is reduced to 1.5 μm or less by the compression process described later, the influence of the rolling marks can be sufficiently reduced. The surface roughness of the metal foil can be made smaller than the surface roughness of the rolling marks based on the original foil, and unnecessary oxides along the rolling marks can be removed. In addition, when the surface roughness Ra of the metal foil is 0.1 μm or more, the surface area of ​​the metal foil can be sufficiently ensured, and it is easy to increase the capacity.

[0045] In the pore distribution of the porous portion measured by mercury penetration, it is preferred that V S1 / V0≤0.07. Preferably, V S2 / V0≤0.05 (or 0.04). When the glossiness G1 is 10 or more, V S1 / V0 (further, V S2 / V0) is likely to be within the above range.

[0046] V0 is the cumulative pore volume (cm2) of pores with a diameter of 0.01 μm or more and 1 μm or less. 3 / g). V S1 The cumulative pore volume (cm2) of pores with a diameter of 0.01 μm or more and 0.06 μm or less 3 / g). V S2 The cumulative pore volume (cm2) of pores with a diameter of 0.01 μm or more and 0.05 μm or less 3 / g). The pore size distribution can be measured using, for example, AutoPore V series manufactured by Micromeritics.

[0047] Small pores with a pore diameter of 0.01 μm or more and 0.06 μm or less (or 0.05 μm or less) are easily clogged by the dielectric layer, which is disadvantageous in terms of high capacity, low ESR and strength. The part of the porous portion where the pores are blocked by the dielectric layer not only does not contribute to the increase in capacity, but also becomes hard and brittle. When the number of small pores increases and the number of the above-mentioned blocked parts increases, the strength of the electrode foil decreases, and in the manufacturing process of the electrolytic capacitor (conveying, slitting, winding, connection with the lead member based on riveting, etc.), cracks sometimes occur in the electrode foil or the foil breaks. In V S1 / V0 (further, V S2 When V0 / V0) is within the above range, there are fewer small pores, and pores with a pore diameter suitable for increasing the capacity are distributed in large quantities, which facilitates high capacity. In addition, in this case, there are fewer blocked parts, which facilitates the suppression of strength reduction.

[0048] In addition, in the pore distribution of the porous portion measured by mercury penetration, it is preferred that V L1 / V0≤0.4, more preferably, further satisfying V L2 / V0≤0.1 (or 0.08). When the glossiness G1 is 10 or more, V L1 / V0 (further, V L2 / V0) is likely to be within the above range.

[0049] In addition, V L1 The cumulative pore volume (cm2) of pores with a diameter of 0.16 μm or more and 1 μm or less 3 / g). V L2 The cumulative pore volume (cm2) of pores with a diameter of 0.5 μm or more and 1 μm or less 3 / g).

[0050] Large pores with a pore diameter of 0.16 μm or more (or 0.5 μm or more) and 1 μm or less are unlikely to contribute to an increase in capacity. Large pores are disadvantageous in terms of expanding the surface area of ​​the electrode foil. For example, in the case of large pores, when two pores are formed in close proximity, they are compressed against each other, and the circumference of the pores (the total length of the contour of the inner wall of the pores present per unit area of ​​the cross section of the porous portion) tends to decrease, making it difficult to contribute to an increase in capacity. L1 / V0 (further, V L2 When V0 / V0) is within the above range, there are fewer large pores, and pores having a pore diameter suitable for increasing the capacity are distributed in large numbers, so that the surface area of ​​the electrode foil is likely to be increased, and the capacity is likely to be increased.

[0051] From the viewpoint of improving strength and capacity, the thickness T of the metal foil is A For example, it is 90 μm or more, preferably 110 μm or more, and more preferably 120 μm or more. A The thickness T of the porous portion may be 25 μm to 90 μm, or 35 μm to 80 μm. A When it is within the above range, the thickness of the core portion can be sufficiently ensured, and the thickness T of the porous portion can be increased within the above range. The thickness of the core portion may be, for example, 20 μm or more, or 25 μm or more.

[0052] The thickness of the metal foil is T A When the glossiness G1 is larger (for example, within the above range), the stress generated in the metal foil (surface layer) during winding becomes larger, so the effect of improving the surface layer strength (the effect of suppressing the occurrence of cracks caused by this stress) when the glossiness G1 is 10 or more is significantly obtained.

[0053] The metal foil contains a valve metal. Examples of valve metals include aluminum (Al), tantalum (Ta), and niobium (Nb). The metal foil may be a foil of a valve metal (e.g., Al) or a foil of an alloy or compound containing a valve metal (e.g., Al). When the metal foil is used as an anode foil, a dielectric layer may be formed by covering the metal skeleton constituting the porous portion. The dielectric layer is, for example, a layer containing an oxide of a valve metal.

[0054] Here, Figure 1 It is a cross-sectional view schematically showing an example of an electrode foil for an electrolytic capacitor according to an embodiment of the present disclosure. Figure 1 The cross section of the electrode foil in the thickness direction is shown. In addition, the electrode foil for electrolytic capacitors according to the present disclosure is not limited to this.

[0055] The electrode foil (metal foil 300) contains a valve-acting metal and includes a core 330 and porous portions 310 and 320 connected to the core 330. The metal foil 300 has a first main surface S1 and a second main surface S2 opposite to the first main surface S1. The porous portion 310 and the porous portion 320 are formed with the core 330 interposed therebetween. The porous portion 310 has the main surface S1 of the metal foil 300. The porous portion 320 has the main surface S2 of the metal foil 300.

[0056] The first glossiness G at the incident angle of 20 degrees on the first main surface S1 1-1 and the second glossiness G at an incident angle of 20 degrees on the second main surface S2 1-2 At least one of the first glossiness G1 is 10 or more. Preferably, the first glossiness G 1-1 And the second glossiness G 1-2 All are above 10. 1st glossiness G 1-1 Can also be used with 2nd glossiness G 1-2 In this case, in the wound body, it is preferred that the metal foil is wound so that the first glossiness G 1-1 And the second glossiness G 1-2 The main surface of any larger side is toward the outer peripheral side of the winding body. In this case, the tensile stress generated on the main surface of the outer peripheral side of the winding body during winding is greater, so the effect of improving the strength of the surface layer (the effect of suppressing the generation of cracks during winding) is significantly obtained.

[0057] The porous portion 310 has a thickness T (μm) and includes an inner layer region 312 on the core portion 330 side and a surface layer region 311 on the opposite side to the core portion 330. The surface layer region 311 is a region that is T / 4 or less from the outer surface S of the porous portion 310. The inner layer region 312 is a region that is T / 4 or less from the boundary B between the porous portion 310 and the core portion 330. 1-1 When φ is 10 or less, the average diameter D1 (nm) of the pores in the surface region 311 can be smaller than the average diameter D2 (nm) of the pores in the inner region 312. The same can be said for the porous portion 320 (the surface region 321 and the inner region 322).

[0058] (Method for producing electrode foil for electrolytic capacitor)

[0059] The manufacturing method of the electrode foil for electrolytic capacitor involved in the embodiment of the present disclosure includes: an etching process of etching a sheet containing a valve-acting metal to form a porous portion on the main surface of the sheet, and a compression process of compressing the etched sheet in the thickness direction to form a main surface of the sheet with a glossiness G1 of 10 or more at an incident angle of 20 degrees.

[0060] The sheet used for etching (hereinafter also referred to as "raw sheet") contains a valve metal. Examples of the valve metal include Al, Ta, and Nb. The raw sheet may be a sheet of a valve metal (e.g., Al), or a sheet containing an alloy or compound containing a valve metal (e.g., Al). As the raw sheet, a long strip or strip-shaped rolled sheet (rolled foil) is generally used.

[0061] A porous portion is formed on the main surface of the sheet by etching, and the portion other than the porous portion remains as a core portion. That is, the sheet after etching has a core portion and a porous portion continuous with the core portion, and the porous portion has the main surface of the sheet. The porous portion is usually formed on the two main surfaces of the sheet, sandwiching the core portion. In the compression process, the sheet having the porous portion formed by etching is compressed. The strength of the surface layer of the porous portion is relatively small, and it is easy to be compressed in the compression process.

[0062] Through the above compression process (by appropriately adjusting the thickness reduction rate, etc.), glossiness, D1 / D2, P1 / P2, V S1 / V0、V S2 / V0、V L1 / V0、V L2 / V0, etc. are controlled within the above range.

[0063] During the manufacturing process of electrolytic capacitors, the sheet comes into contact with the processing liquid (such as etching solution, chemical solution) and rollers, which will produce bumps (or damage). During the manufacturing process, stress is concentrated on the bumps, and sometimes the sheet will break (or cracks will occur on the sheet). In addition, the Al original foil used for the sheet has rolling marks generated during the manufacturing process, and etching pits will be unevenly formed along the rolling marks, that is, along the length direction (rolling direction) of the long sheet. Due to the influence of the rolling marks, the sheet sometimes breaks (or cracks will occur on the sheet). In contrast, as mentioned above, by appropriately compressing the sheet after the etching process, the influence of the above-mentioned bumps and rolling marks is reduced, the strength of the surface layer of the sheet is improved, and the above-mentioned sheet breakage is suppressed.

[0064] After the compression process, the thickness of the sheet is A The thickness T of each single surface of the porous portion after the compression step may be 90 μm or more and 200 μm or less, or 120 μm or more and 200 μm or less. A / 2)-10}μm or less. When the thickness T is within the above range, the core can be ensured with sufficient thickness. In addition, the thickness T can be greater than 25μm and less than 90μm, or greater than 35μm and less than 80μm. In high-capacity foils, the thickness T of the porous part is large, and the effect of improving the surface strength based on compression is significantly obtained. In particular, in hybrid capacitors, high-capacity foils are used, and the thickness T of the sheet (electrode foil) is A It is preferably 90 μm or more, and the thickness T of the porous portion is preferably 25 μm or more.

[0065] (Etching process)

[0066] In the etching step, the surface of the valve metal sheet is etched to roughen the surface of the sheet and form a porous portion continuous with the core. The etching may be electrolytic etching or chemical etching and can be performed using a known method.

[0067] From the perspective of forming pores with larger diameters, electrolytic etching can be performed at 2.0 A / cm 2 The current density can be as low as 1.5A / cm 2 The current density can be as low as 1.2A / cm 2 The etching is performed at the following current density. The current density can also be changed during etching. A larger pore diameter makes it easier to form a thicker dielectric layer, which is advantageous in terms of increasing the voltage.

[0068] Electrolytic etching is preferably AC etching, but may also be DC etching. In the case of AC etching, it is easy to form a porous portion containing sponge-like pits with a relatively small diameter. In the case of DC etching, it is easy to form a porous portion containing tunnel-like pits with a relatively large diameter.

[0069] When the etching time is set to T E When the temperature is between 0 and 0.7 T, E The temperature of the etching solution is set to 10°C or higher and 60°C or lower. E ~T E The temperature of the etching solution is set to 5° C. or higher and 40° C. or lower. In this case, the variation in the pit diameter in the thickness direction of the porous portion can be reduced. E For example, it is 15 minutes to 30 minutes.

[0070] (Compression process)

[0071] In the compression step, the etched sheet may be conveyed between a pair of rollers and compressed. The etched sheet conveyed between a pair of rollers is compressed by the pair of rollers. As described later, by appropriately adjusting the roller pressing conditions, it is easy to adjust the glossiness, D1 / D2 (further, P1 / P2), V S1 / V0 (further, V S2 / V0) and V L1 / V0 (further, V L2 / V0) is controlled within the above range.

[0072] A pair of rollers may be arranged in multiple stages to compress the sheet in stages. In this case, the diameter of the pair of rollers may be changed at each stage, or may be reduced as the compression of the sheet progresses. The compression process may also include a sheet conveying process using rollers and a sheet winding process after compression. By compression, the strength of the surface layer of the sheet is increased, and the breakage of the sheet when the sheet is wound using rollers is suppressed.

[0073] Here, Figure 2 It is a structural diagram showing an example of a compression process. Figure 2 The X in the figure represents the conveying direction of the long strip of sheet material 400. In the compression process, for example, Figure 2 The compression device shown in FIG. 4 includes a pair of rollers 500 for compressing the sheet 400. The thickness T after etching B The sheet 400 of thickness T is compressed by the pair of rollers 500 to a thickness T. A (mm). The sheet feeding speed may be 0.5 m / min or more, or 0.5 m / min or more and 50 m / min or less.

[0074] From the viewpoint of facilitating the production of the electrode foil, the thickness reduction rate of the sheet in the compression process is preferably 5% to 40%, more preferably 10% to 30%, and even more preferably 10% to 25%. B Reduce to T A When passing {(T B -T A ) / T B}×100 and calculate the value.

[0075] When roller 500 is viewed from the direction of its rotation axis, contact region 410 between roller 500 and sheet 400 is arc-shaped, and a center angle θ of the arc of roller 500 relative to contact region 410 may be 0.15° to 1.5° (or 1.75° or less).

[0076] When the area obtained by projecting the contact area 410 between the sheet 400 and the roller 500 onto a virtual plane parallel to the main surface of the sheet 400 is defined as the projection area, the length L of the projection area in the conveying direction X of the sheet 400 may be greater than or equal to 0.5 mm and less than or equal to 5 mm.

[0077] The sheet 400 may be compressed with a linear pressure of 0.55 kN / cm or more and 14 kN / cm or less. The diameter D of the roller 500 may be 75 mm or more and 1800 mm or less. The thickness T0 (mm) of the porous portion of the sheet 400 before compression and the diameter D (mm) of the roller 500 may also satisfy the relationship of 380≤D / T0≤9800.

[0078] The device may further include rollers for conveying the sheet 400, and may further include rollers for winding up the compressed sheet 400. The device may also include a control unit for controlling the rotation speed of the rollers 500, etc. The feeding speed of the sheet 400 may also be controlled by the control unit.

[0079] The manufacturing method of the electrode foil may also include a step of slitting the compressed sheet. In the slitting process, a slitting device and a roller for winding the slitting sheet are used. By compression, the strength of the surface layer of the sheet is improved, and the breakage of the sheet when the sheet is wound by the roller is suppressed.

[0080] (Electrolytic capacitors)

[0081] The electrode foil for electrolytic capacitors according to the embodiment of the present disclosure is suitable for use in an electrolytic capacitor having a wound capacitor element. The wound capacitor element has a winding body and an electrolyte. The winding body is formed by winding an anode foil, a cathode foil, and a separator disposed between the anode foil and the cathode foil. The anode foil has an electrode foil according to the embodiment of the present disclosure (hereinafter also referred to as "electrode foil A"), and a dielectric layer covering a metal skeleton constituting a porous portion of the electrode foil A.

[0082] In electrolytic capacitors with a rated voltage of 20V or more, for example, Al foil that has been subjected to a formation treatment at a formation voltage of 30V or more is used as an anode foil. In addition, in electrolytic capacitors with a solid electrolyte (conductive polymer) and an electrolyte, for example, Al foil that has been subjected to a formation treatment at a formation voltage of 40V or more is often used as an anode foil. In such an anode foil, an electrode foil with a relatively large pit diameter is used to form a dielectric layer with a relatively large thickness (for example, a thickness of 45nm or more), and the strength of the surface layer is easily reduced. Therefore, a significant improvement effect based on the surface strength of the electrode foil A is obtained. If the formation voltage is 30V or more (or 40V or more), the generated formation film becomes thicker, so by using an electrode foil with a larger pit diameter, the clogging of the pits caused by the thicker formation film is suppressed, and high capacity can be efficiently achieved.

[0083] (Anode foil)

[0084] The anode foil includes an electrode foil A and a dielectric layer covering a metal skeleton constituting a porous portion of the electrode foil A. The dielectric layer can form an oxide film of a valve metal on the surface of the metal skeleton constituting the porous portion by, for example, anodization (chemical formation treatment). When the Al foil is subjected to chemical formation treatment, the chemical formation voltage can be, for example, 5V or more, or 40V or more.

[0085] When the glossiness G1 of electrode foil A is 10 or more, the glossiness G2 of the main surface of the anode foil at an incident angle of 20 degrees is 10 or more. The glossiness G2 of the main surface of the anode foil including electrode foil A is substantially the same as the glossiness G1 of the main surface of electrode foil A.

[0086] The main surface of the anode foil may also include a first main surface and a second main surface on the opposite side of the first main surface. The porous portion may also include a first porous portion having a first main surface and a second porous portion having a second main surface via a core portion. The dielectric layer may also include a first dielectric layer covering a metal skeleton constituting the first porous portion and a second dielectric layer covering a metal skeleton constituting the second porous portion. In this case, the first glossiness G at an incident angle of 20 degrees on the first main surface is 2-1 And the second glossiness G of the second main surface at an incident angle of 20 degrees 2-2 At least one of the first glossiness G is 10 or more. Preferably, the first glossiness G 2-1 And the second glossiness G 2-2 Both of them have a glossiness G2 of 10 or more. 2-1 It can also be greater than the second glossiness G 2-2In this case, in the wound body, the anode foil is preferably wound with the first main surface facing the outer peripheral side of the wound body. The anode foil is arranged so that the first main surface with a higher glossiness (higher surface strength) becomes the main surface on the outer peripheral side of the wound body where a larger tensile stress is generated during winding, thereby significantly obtaining an effect of suppressing the generation of cracks caused by the stress generated during winding.

[0087] The thickness of the anode foil may be 60 μm or more and 200 μm or less, 90 μm or more and 200 μm or less, or 120 μm or more and 200 μm or less. The thickness of the dielectric layer is, for example, 45 nm or more.

[0088] (Cathode foil)

[0089] For the cathode foil, a metal foil containing a valve metal such as Al, Ta, or Nb can be used. The surface of the metal foil can also be roughened by etching as needed. That is, the cathode foil can also be a metal foil having a porous portion and a core portion continuous with the porous portion. The electrode foil for electrolytic capacitors disclosed in the present invention can also be used for the cathode foil. The thickness of the cathode foil is, for example, not less than 10 μm and not more than 70 μm.

[0090] (Isolator)

[0091] The separator is not particularly limited, and for example, nonwoven fabrics containing fibers of cellulose, polyethylene terephthalate, vinylon, or polyamide (for example, aliphatic polyamide, aromatic polyamide such as aramid) may be used.

[0092] (Electrolytes)

[0093] The electrolyte covers at least a portion of the anode foil (dielectric layer) and is disposed between the anode foil (dielectric layer) and the cathode foil. The electrolyte includes at least one of a solid electrolyte and an electrolyte solution. The capacitor element may include a solid electrolyte or a solid electrolyte and a liquid component (electrolyte solution or non-aqueous solvent).

[0094] The dielectric layer is coated with an electrolyte, for example, by impregnating the anode foil (or the wound body) with a treatment solution (or electrolyte) containing a conductive polymer. In the above-mentioned electrode foil, since D1 is smaller than D2 (furthermore, P1 is smaller than P2), the treatment solution impregnated in the porous portion is easily retained in the pores, and the inner wall of the pores is easily covered with the electrolyte, thereby improving the contact between the anode foil (dielectric layer) and the electrolyte.

[0095] The solid electrolyte includes a conductive polymer. As the conductive polymer, for example, a π-conjugated polymer can be cited. As the conductive polymer, polypyrrole, polythiophene, polyfuran, polyaniline, etc. can be cited. The conductive polymer can be used alone or in combination of two or more, or it can be a copolymer of two or more monomers. The weight average molecular weight of the conductive polymer is, for example, 1000 to 100000.

[0096] In addition, in this specification, polypyrrole, polythiophene, polyfuran, polyaniline, etc. respectively refer to polymers having polypyrrole, polythiophene, polyfuran, polyaniline, etc. as basic skeletons. Therefore, polypyrrole, polythiophene, polyfuran, polyaniline, etc. may also include their respective derivatives. For example, polythiophene includes poly(3,4-ethylenedioxythiophene) and the like.

[0097] The conductive polymer can be doped with a dopant. The solid electrolyte may also contain a dopant together with the conductive polymer. Examples of the dopant include polystyrene sulfonic acid and the like. The solid electrolyte may further contain an additive as required.

[0098] The liquid component may be an electrolyte or a non-aqueous solvent. The electrolyte contains a non-aqueous solvent and an ionic substance (solute (eg, an organic salt)) dissolved therein. The non-aqueous solvent may be an organic solvent or an ionic liquid.

[0099] As the non-aqueous solvent, a high boiling point solvent is preferred. For example, polyol compounds such as ethylene glycol, sulfone compounds such as cyclopentane, lactone compounds such as γ-butyrolactone, ester compounds such as methyl acetate, carbonate compounds such as propylene carbonate, ether compounds such as 1,4-dioxane, ketone compounds such as methyl ethyl ketone, etc. can be used.

[0100] The liquid component may contain an acid component (anion) and an alkaline component (cation). A salt (solute) may also be formed by the acid component and the alkaline component. The acid component contributes to the membrane repair function. As the acid component, organic carboxylic acids, inorganic acids, etc. may be listed. As inorganic acids, for example, phosphoric acid, boric acid, sulfuric acid, etc. may be listed. As the alkaline component, for example, amine compounds of level 1 to level 3 may be listed.

[0101] The so-called organic salt refers to a salt in which at least one of the anion and the cation contains an organic substance. As the organic salt, for example, trimethylammonium maleate, triethylammonium borodisalicylate, ethyldimethylamine phthalate, 1,2,3,4-tetramethylimidazolinium phthalate, 1,3-dimethyl-2-ethylimidazolinium phthalate, etc. can also be used.

[0102] From the viewpoint of suppressing dedoping of the conductive polymer by the dopant (deterioration of the solid electrolyte), it is preferred that the liquid component contains more acid components than the alkaline components. In addition, from the viewpoint that the acid component contributes to the membrane repair function of the liquid component, it is also preferred that the acid component contains more acid components than the alkaline components. The molar ratio of the acid component to the alkaline component, i.e., (acid component / alkaline component), is, for example, 1.1 or more. From the viewpoint of suppressing dedoping of the conductive polymer by the dopant, the pH of the liquid component may be 6 or less, or may be 1 or more and 5 or less.

[0103] Here, Figure 3 It is a cross-sectional view schematically showing an example of an electrolytic capacitor according to an embodiment of the present disclosure. Figure 4 It is schematically shown Figure 3 A three-dimensional diagram of the structure of the winding body.

[0104] Electrolytic capacitor 200 includes a capacitor element, and the capacitor element includes a wound body 100 and an electrolyte (not shown). Wound body 100 is formed by winding anode foil 10 and cathode foil 20 with separator 30 interposed therebetween.

[0105] One end of lead tabs 50A and 50B is connected to anode foil 10 and cathode foil 20, respectively, and lead tabs 50A and 50B are wound around to form winding body 100. Leads 60A and 60B are connected to the other ends of lead tabs 50A and 50B, respectively.

[0106] A winding fixing tape 40 is disposed on the outer surface of the cathode foil 20 located at the outermost layer of the wound body 100, and the end of the cathode foil 20 is fixed by the winding fixing tape 40. In addition, when the anode foil 10 is prepared by cutting from a large sheet of foil, the wound body 100 may be further subjected to a chemical treatment in order to provide a dielectric layer on the cut section.

[0107] The electrolyte is interposed between anode foil 10 (dielectric layer) and cathode foil 20 in wound body 100. The capacitor element is obtained by, for example, impregnating wound body 100 with a treatment solution containing an electrolyte. The impregnation may be performed under reduced pressure, for example, in an atmosphere of 10 kPa to 100 kPa.

[0108] The wound body 100 is housed in the bottomed case 211 so that the leads 60A and 60B are located on the opening side of the bottomed case 211. As the material of the bottomed case 211, a metal such as aluminum, stainless steel, copper, iron, brass, or an alloy thereof can be used.

[0109] A sealing member 212 is arranged at the opening of a bottom shell 211 accommodating the wound body 100 and the electrolyte, the open end of the bottom shell 211 is riveted to the sealing member 212 and curled, and a seat plate 213 is arranged at the curled portion, thereby sealing the wound body 100 in the bottom shell 211.

[0110] The sealing member 212 is formed so that the lead wires 60A and 60B pass through it. The sealing member 212 may be made of any insulating material, and is preferably an elastomer. Among them, silicone rubber, fluororubber, ethylene-propylene rubber, Hypalon rubber, butyl rubber, isoprene rubber, etc., which have high heat resistance, are preferred.

[0111] The electrode foil involved in the embodiment of the present disclosure can be used for an electrolytic capacitor having the above-mentioned wound capacitor element, but can also be used for an electrolytic capacitor having a stacked capacitor element. In this case, the porous portion is formed in a region of a portion of the surface of the electrode foil. The stacked capacitor element comprises an anode body, a solid electrolyte layer, and a cathode lead layer covering the solid electrolyte layer. The anode body comprises the above-mentioned electrode foil having a porous portion formed on a portion of the surface, and a dielectric layer covering a metal skeleton constituting the porous portion of the electrode foil. The solid electrolyte layer is formed to cover the dielectric layer. The cathode lead layer comprises, for example, a silver paste layer and a carbon layer. The region of the anode body not covered by the dielectric layer is connected to the anode lead, and the cathode lead layer is connected to the cathode lead.

[0112] Postscript

[0113] The following techniques are disclosed through the description of the above embodiments.

[0114] (Technique 1)

[0115] An electrode foil for an electrolytic capacitor, comprising:

[0116] Metal foils, including valve action metals,

[0117] The metal foil has a core portion and a porous portion continuous with the core portion.

[0118] The porous portion has a main surface of the metal foil,

[0119] The glossiness G1 of the main surface at an incident angle of 20 degrees is 10 or more.

[0120] (Technique 2)

[0121] In the electrode foil for electrolytic capacitor according to the technique 1,

[0122] The glossiness G1 is 10 or more and 140 or less.

[0123] (Technique 3)

[0124] In the electrode foil for electrolytic capacitor according to the technique 1 or 2,

[0125] The metal foil includes Al.

[0126] (Technique 4)

[0127] In the electrode foil for electrolytic capacitor according to any one of techniques 1 to 3,

[0128] The glossiness G1 is measured by making light incident on the main surface in parallel with the longitudinal direction of the long metal foil when viewed from the normal direction of the main surface.

[0129] (Technique 5)

[0130] In the electrode foil for electrolytic capacitor according to any one of techniques 1 to 4,

[0131] The porous portion has a thickness T and includes an inner layer region on the core side and a surface layer region on the opposite side to the core.

[0132] The surface region is a region that is at a distance of T / 4 or less from the outer surface of the porous portion.

[0133] The inner layer region is a region whose distance from the boundary between the porous portion and the core portion is less than or equal to T / 4.

[0134] An average diameter D1 of the pores in the surface layer region is smaller than an average diameter D2 of the pores in the inner layer region.

[0135] (Technique 6)

[0136] In the electrode foil for electrolytic capacitor according to the technique 5,

[0137] The ratio of the D1 to the D2, that is, D1 / D2, is greater than or equal to 0.5 and less than or equal to 0.98.

[0138] (Technique 7)

[0139] In the electrode foil for electrolytic capacitor according to the technique 5 or 6,

[0140] The porosity P1 of the surface layer region is smaller than the porosity P2 of the inner layer region.

[0141] (Technique 8)

[0142] In the electrode foil for electrolytic capacitor according to technology 7,

[0143] The ratio of the P1 to the P2, that is, P1 / P2, is greater than or equal to 0.5 and less than or equal to 0.95.

[0144] (Technique 9)

[0145] In the electrode foil for electrolytic capacitor according to any one of techniques 1 to 8,

[0146] The surface roughness Ra of the metal foil is 1.5 μm or less.

[0147] (Technology 10)

[0148] In the electrode foil for electrolytic capacitor according to any one of techniques 1 to 9,

[0149] In the pore distribution of the porous portion measured by mercury penetration,

[0150] Cumulative pore volume V0 (cm2) of pores with diameters of 0.01 μm or more and 1 μm or less 3 / g) and a cumulative pore volume V of pore diameters of 0.01 μm or more and 0.06 μm or less S1 (cm 3 / g) satisfies the following relationship:

[0151] V S1 / V0≤0.07.

[0152] (Technology 11)

[0153] In the electrode foil for electrolytic capacitor according to any one of techniques 1 to 10,

[0154] In the pore distribution of the porous portion measured by mercury penetration,

[0155] Cumulative pore volume V0 (cm2) of pores with diameters of 0.01 μm or more and 1 μm or less 3 / g) and a cumulative pore volume V of pore diameters of 0.16 μm or more and 1 μm or less L1 (cm 3 / g) satisfies the following relationship:

[0156] V L1 / V0≤0.4.

[0157] (Technology 12)

[0158] In the electrode foil for electrolytic capacitor according to any one of techniques 1 to 11,

[0159] The thickness T of the metal foil A It is 90 μm or more and 200 μm or less.

[0160] (Technology 13)

[0161] In the electrode foil for electrolytic capacitor according to any one of techniques 1 to 12,

[0162] The thickness T of the porous portion is greater than or equal to 25 μm and less than or equal to 90 μm.

[0163] (Technology 14)

[0164] In the electrolytic capacitor electrode foil according to any one of techniques 1 to 13,

[0165] The main surface of the metal foil includes a first main surface and a second main surface opposite to the first main surface.

[0166] The porous portion includes a first porous portion having the first main surface and a second porous portion having the second main surface via the core portion.

[0167] The first glossiness G of the first main surface at an incident angle of 20 degrees 1-1 and the second glossiness G of the second main surface at an incident angle of 20 degrees 1-2 At least one of the above is the glossiness G1.

[0168] (Technology 15)

[0169] In the electrode foil for electrolytic capacitor according to technology 14,

[0170] The first glossiness G 1-1 With the second glossiness G 1-2 different.

[0171] (Technology 16)

[0172] An electrolytic capacitor,

[0173] With capacitor element,

[0174] The capacitor element comprises a winding body and an electrolyte.

[0175] The wound body is formed by winding an anode foil, a cathode foil, and a separator disposed between the anode foil and the cathode foil.

[0176] The anode foil comprises: the electrode foil according to claim 1; and a dielectric layer covering a metal skeleton constituting the porous portion of the electrode foil.

[0177] (Technology 17)

[0178] In the electrode foil for the electrolytic capacitor described in Technology 16,

[0179] The thickness of the dielectric layer is greater than 45 nm.

[0180] (Technology 18)

[0181] In the electrolytic capacitor described in technology 16 or 17,

[0182] The capacitor element includes a solid electrolyte as the electrolyte and may further include a liquid component.

[0183] The solid electrolyte includes a conductive polymer.

[0184] (Technology 19)

[0185] In the electrolytic capacitor described in any one of Techniques 16 to 18,

[0186] The main surface of the anode foil has a glossiness G2 of 10 or more at an incident angle of 20 degrees.

[0187] (Technology 20)

[0188] In the electrolytic capacitor described in technology 19,

[0189] The main surface of the anode foil includes a first main surface and a second main surface opposite to the first main surface.

[0190] The porous portion includes a first porous portion having the first main surface and a second porous portion having the second main surface via the core portion.

[0191] The dielectric layer includes: a first dielectric layer covering the metal skeleton constituting the first porous portion; and a second dielectric layer covering the metal skeleton constituting the second porous portion.

[0192] The first glossiness G of the first main surface at an incident angle of 20 degrees 2-1 and the second glossiness G of the second main surface at an incident angle of 20 degrees 2-2 At least one of the glossiness is G2.

[0193] (Technology 21)

[0194] In the electrolytic capacitor described in technology 20,

[0195] The first glossiness G 2-1 Greater than the second glossiness G 2-2 ,

[0196] In the wound body, the anode foil is wound such that the first main surface faces the outer peripheral side of the wound body.

[0197] (Technology 22)

[0198] A method for manufacturing an electrode foil for an electrolytic capacitor, comprising:

[0199] an etching step of etching a sheet containing a valve-acting metal to form porous portions on both main surfaces of the sheet; and

[0200] The sheet after the etching process is compressed in the thickness direction to form the main surface having a glossiness G1 of 10 or more at an incident angle of 20 degrees.

[0201] (Technology 23)

[0202] In the method for manufacturing an electrode foil for an electrolytic capacitor according to technique 22,

[0203] The glossiness G1 is 10 or more and 140 or less.

[0204] (Technology 24)

[0205] In the method for manufacturing an electrode foil for an electrolytic capacitor according to technology 22 or 23,

[0206] The sheet includes Al.

[0207] (Technology 25)

[0208] In the method for producing an electrode foil for an electrolytic capacitor according to any one of Techniques 22 to 24,

[0209] After the compression process, the thickness of the sheet is T A (μm) and the thickness T (μm) of each single surface of the porous portion satisfy the following relationship:

[0210] 90≤T A ≤200 and 25≤T≤(T A / 2)-10.

[0211] (Technology 26)

[0212] In the method for producing an electrode foil for an electrolytic capacitor according to any one of Techniques 22 to 25,

[0213] In the etching process, the 2 Electrolytic etching was performed at the following current density.

[0214] (Technology 27)

[0215] In the method for producing an electrode foil for an electrolytic capacitor according to any one of Techniques 22 to 26,

[0216] In the compression step, the thickness of the sheet is reduced by 5% or more and 40% or less.

[0217] (Technology 28)

[0218] In the method for producing an electrode foil for an electrolytic capacitor according to any one of Techniques 22 to 27,

[0219] In the compression step, the sheet is conveyed between a pair of rollers and compressed.

[0220] (Technology 29)

[0221] In the method for manufacturing an electrode foil for an electrolytic capacitor according to technique 28,

[0222] The sheet feeding speed is 0.5 m / min or more.

[0223] (Technology 30)

[0224] In the method for manufacturing an electrode foil for an electrolytic capacitor according to technology 28 or 29,

[0225] When the roller is viewed from the direction of the rotation axis of the roller, the contact area between the roller and the sheet is in the shape of an arc.

[0226] A central angle θ of the roller with respect to the arc of the contact region is greater than or equal to 0.15° and less than or equal to 1.5°.

[0227] (Technology 31)

[0228] In the method for producing an electrode foil for an electrolytic capacitor according to any one of Techniques 28 to 30,

[0229] When a region obtained by projecting a contact region between the sheet and the roller onto a virtual plane parallel to the main surface of the sheet is defined as a projection region,

[0230] A length L of the projection area in the conveyance direction of the sheet is greater than or equal to 0.5 mm and less than or equal to 5 mm.

[0231] (Technology 32)

[0232] In the method for producing an electrode foil for an electrolytic capacitor according to any one of Techniques 22 to 31,

[0233] The sheet is compressed at a linear pressure of 0.55 kN / cm or more and 14 kN / cm or less.

[0234] (Technology 33)

[0235] In the method for producing an electrode foil for an electrolytic capacitor according to any one of Techniques 22 to 32,

[0236] The thickness T0 (mm) of the porous portion before compression of the sheet and the diameter D (mm) of the roller satisfy the relationship of 380≤D / T0≤9800.

[0237] [Example]

[0238] Hereinafter, the present disclosure will be described in more detail based on examples, but the present disclosure is not limited to the examples.

[0239] 《Examples 1-2》

[0240] (Etching process)

[0241] For Al foil (thickness T B :130μm) was etched to form porous parts on both surfaces of the Al sheet (thickness T0 of each single surface: 30μm). During the etching process, AC etching was performed at 1.5A / cm 2 The current density was appropriately adjusted within the following range and the etching time was appropriately adjusted to achieve a predetermined melting amount.

[0242] (Compression process)

[0243] The Al sheet after etching was compressed in the thickness direction to obtain electrode foils a1 to a2. In the compression step, the thickness of the sheet was reduced at the ratio (reduction rate) shown in Table 1. A (μm) and the thickness T (μm) per single surface of the porous portion were set to the values ​​shown in Table 2.

[0244] like Figure 2 As shown, in the compression process, the Al sheet is conveyed between a pair of rollers (diameter D: 75 mm) and compressed. The pressing force and linear pressure of the rollers are set to the values ​​shown in Table 1. The feeding speed of the Al sheet is set to the values ​​shown in Table 1. The ratio of the diameter D (mm) of the roller to the thickness T0 (mm) of the porous part before the sheet is compressed, i.e., D / T0, is 2500. Figure 2 The angle θ in is set to the value shown in Table 1. Figure 2 The length L in is set to the value shown in Table 1.

[0245] [Table 1]

[0246]

[0247] The glossiness G1, D1 / D2, and P1 / P2 obtained by the above-mentioned method are the values ​​shown in Table 2. The arithmetic mean roughness Ra of the electrode foil is the value shown in Table 2. S1 / V0、V S2 / V0、V L1 / V0 and V L2 / V0 is the value shown in Table 2. In the electrode foils a1 to a2, the glossiness G S (60°) is 60 or above, glossiness G S (85°) is above 85.

[0248] [Table 2]

[0249]

[0250] (Formation of dielectric layer)

[0251] Electrode foils a1 and a2 are subjected to chemical conversion treatment to form a dielectric layer, which covers the metal skeleton constituting the porous part. The chemical conversion treatment is based on the test method for electrode foil for aluminum electrolytic capacitors of the Japanese Electronic Machinery Industry Standard (EIAJRC-2364A) and is performed at a conversion voltage of 65V. In this way, anode foils A1 and A2 are produced. The glossiness G2 of anode foils A1 and A2 obtained by the above-mentioned method is the value shown in Table 3.

[0252] The electrode foils a1 and a2 are those of Examples 1 and 2, and the anode foils A1 and A2 are chemically converted products of the electrode foils a1 to a5.

[0253] Comparative Example 1

[0254] Electrode foil b1 was produced in the same manner as electrode foil a1, except that the Al sheet was not compressed after etching. Anode foil B1 was produced in the same manner as anode foil A1, except that electrode foil b1 was used instead of electrode foil a1. The glossiness G2 of anode foil B1 obtained by the above method was the value shown in Table 3.

[0255] (Evaluation 1: Tensile strength of electrode foil)

[0256] For each electrode foil, a strip sample (70 mm in length and 10 mm in width) was prepared, and the tensile strength in the length direction of the sample was measured according to the test method for electrode foil for aluminum electrolytic capacitors of the Japanese Electronic Machinery Industry Standard (EIAJ RC-2364A). The measurement results are shown in Table 1. In Table 2, the tensile strength is shown as a relative value when the tensile strength of electrode foil b1 is set to 100.

[0257] (Evaluation 2: Capacity of anode foil)

[0258] For each anode foil, the electrostatic capacitance was measured in accordance with the test method for electrode foil for aluminum electrolytic capacitors of the Japanese Electronic Machinery Industry Standard (EIAJ RC-2364A). The measurement results are shown in Table 3. In addition, in Table 3, the electrostatic capacitance represents a relative value when the electrostatic capacitance of the anode foil B1 is set to 100. Table 3 also shows the capacity per unit volume of the anode foil.

[0259] [Table 3]

[0260]

[0261] In the electrode foils a1 and a2, higher tensile strength was obtained than that of the electrode foil b1. In the anode foils A1 and A2, good capacity was obtained, and it was confirmed that the capacity per unit volume was high.

[0262] 《Examples 3 to 5》

[0263] (Etching process)

[0264] For Al foil (thickness T B :150μm) was etched to form porous parts on both surfaces of the Al sheet (thickness T0 of each single surface: 60μm). During the etching process, AC etching was performed at 1.5A / cm 2 The current density was appropriately adjusted within the following range, and the etching time was also appropriately adjusted so as to achieve a predetermined dissolution amount.

[0265] (Compression process)

[0266] The Al sheet after etching was compressed in the thickness direction to obtain electrode foils a3 to a5. In the compression step, the thickness of the sheet was reduced at the ratio (reduction rate) shown in Table 4. A (μm) and the thickness T (μm) per single surface of the porous portion were set to the values ​​shown in Table 5.

[0267] like Figure 2 As shown, in the compression process, the Al sheet is conveyed between a pair of rollers (diameter D: 75 mm) and compressed. The pressing force and linear pressure of the rollers are set to the values ​​shown in Table 4. The feeding speed of the Al sheet is set to the values ​​shown in Table 4. The ratio of the diameter D (mm) of the roller to the thickness T0 (mm) of the porous part before the sheet is compressed, i.e., D / T0, is 1250. Figure 2 The angle θ in is set to the value shown in Table 4. Figure 2 The length L in is set to the value shown in Table 4.

[0268] [Table 4]

[0269]

[0270] The glossiness G1, D1 / D2, and P1 / P2 obtained by the above-mentioned method are the values ​​shown in Table 5. The arithmetic mean roughness Ra of the electrode foil is the value shown in Table 5. S1 / V0、V S2 / V0、V L1 / V0 and V L2 / V0 is the value shown in Table 5. In the electrode foils a3 to a5, the glossiness G S (60°) is 60 or above, glossiness G S (85°) is above 85.

[0271] [Table 5]

[0272]

[0273] (Formation of dielectric layer)

[0274] Electrode foils a3 to a5 were subjected to chemical conversion treatment to form a dielectric layer, which covered the metal skeleton constituting the porous portion. The chemical conversion treatment was based on the test method for electrode foil for aluminum electrolytic capacitors of the Japanese Electronic Machinery Industry Standard (EIAJRC-2364A) and was performed at a conversion voltage of 65V. In this way, anode foils A3 to A5 were produced. The glossiness G2 of anode foils A3 to A5 obtained by the above-mentioned method is the value shown in Table 6.

[0275] The electrode foils a3 to a5 are those of Examples 3 to 5, and the anode foils A3 to A5 are chemically converted products of the electrode foils a3 to a5.

[0276] Comparative Example 2

[0277] Electrode foil b2 was produced in the same manner as electrode foil a3, except that the Al sheet was not compressed after etching. Anode foil B2 was produced in the same manner as anode foil A3, except that electrode foil b2 was used instead of electrode foil a3. The glossiness G2 of anode foil B2 obtained by the above-mentioned method was the value shown in Table 6.

[0278] The above-mentioned evaluation 1 was performed on the electrode foils a3 to a5 and b2. The evaluation results are shown in Table 5. In Table 5, the tensile strength is shown as a relative value when the tensile strength of the electrode foil b2 is set to 100. The above-mentioned evaluation 2 was performed on the anode foils A3 to A5 and B2. The evaluation results are shown in Table 6. In Table 6, the electrostatic capacitance represents a relative value when the electrostatic capacitance of the anode foil B2 is set to 100. Table 6 also shows the capacity per unit volume of the anode foil.

[0279] [Table 6]

[0280]

[0281] Electrode foils a3 to a5 had higher tensile strength than electrode foil b2. Anode foils A3 to A5 all had good capacities, and it was confirmed that the capacities per unit volume were high.

[0282] Industrial Applicability

[0283] The electrode foil according to the present disclosure is suitable for use in electrolytic capacitors that require high reliability and capacity.

[0284] The present invention has been described with respect to preferred embodiments at the present time point, but such disclosure should not be construed in a limiting sense. Various modifications and changes will be apparent to those skilled in the art in the art to which the present invention belongs upon reading the above disclosure. Therefore, the appended claims should be construed as including all modifications and changes without departing from the true spirit and scope of the present invention.

[0285] -Explanation of symbols-

[0286] 10: anode foil, 20: cathode foil, 30: separator, 40: winding fixing tape, 50A, 50B: lead connectors, 60A, 60B: leads, 100, 400: winding body, 200: electrolytic capacitor, 211: bottom shell, 212: sealing member, 213: seat plate, 300: electrode foil, 310, 320: porous part, 311: surface area, 312: inner area, 330: core, 400: sheet, 410: contact area, 500: roller.

Claims

1. An electrode foil for an electrolytic capacitor, comprising: Metal foils, including valve action metals, The metal foil has a core portion and a porous portion continuous with the core portion. The porous portion has a main surface of the metal foil, The glossiness G1 of the main surface at an incident angle of 20 degrees is 10 or more.

2. The electrode foil for electrolytic capacitor according to claim 1, wherein The glossiness G1 is 10 or more and 140 or less.

3. The electrode foil for electrolytic capacitor according to claim 1, wherein The metal foil includes Al.

4. The electrode foil for electrolytic capacitor according to claim 1, wherein The glossiness G1 is measured by making light incident on the main surface in parallel with the longitudinal direction of the long metal foil when viewed from the normal direction of the main surface.

5. The electrode foil for electrolytic capacitor according to claim 1, wherein The porous portion has a thickness T and includes an inner layer region on the core side and a surface layer region on the opposite side to the core. The surface region is a region that is at a distance of T / 4 or less from the outer surface of the porous portion. The inner layer region is a region whose distance from the boundary between the porous portion and the core portion is less than or equal to T / 4. An average diameter D1 of the pores in the surface layer region is smaller than an average diameter D2 of the pores in the inner layer region.

6. The electrode foil for electrolytic capacitor according to claim 5, wherein The ratio of the D1 to the D2, that is, D1 / D2, is greater than or equal to 0.5 and less than or equal to 0.

98.

7. The electrode foil for electrolytic capacitor according to claim 5, wherein The porosity P1 of the surface layer region is smaller than the porosity P2 of the inner layer region.

8. The electrode foil for electrolytic capacitor according to claim 7, wherein The ratio of the P1 to the P2, that is, P1 / P2, is greater than or equal to 0.5 and less than or equal to 0.

95.

9. The electrode foil for electrolytic capacitor according to claim 1, wherein The surface roughness Ra of the metal foil is 1.5 μm or less.

10. The electrode foil for electrolytic capacitor according to claim 1, wherein In the pore distribution of the porous portion measured by mercury penetration, The cumulative pore volume V0 of pores with a diameter of 0.01 μm or more and 1 μm or less and the cumulative pore volume V of pores with a diameter of 0.01 μm or more and 0.06 μm or less S1 The following relationship is satisfied: In S1 / V0≤0.07, The unit of V0 is cm 3 / g,V S1 The unit is cm 3 / g.

11. The electrode foil for electrolytic capacitor according to claim 1, wherein In the pore distribution of the porous portion measured by mercury penetration, The cumulative pore volume V0 of pores with a diameter of 0.01 μm or more and 1 μm or less and the cumulative pore volume V of pores with a diameter of 0.16 μm or more and 1 μm or less L1 The following relationship is satisfied: In L1 / V0≤0.4, The unit of V0 is cm 3 / g,V L1 The unit is cm 3 / g.

12. The electrode foil for electrolytic capacitor according to claim 1, wherein The thickness T of the metal foil A It is 90 μm or more and 200 μm or less.

13. The electrode foil for electrolytic capacitor according to claim 1, wherein The thickness T of the porous portion is greater than or equal to 25 μm and less than or equal to 90 μm.

14. The electrode foil for electrolytic capacitor according to claim 1, wherein The main surface of the metal foil includes a first main surface and a second main surface opposite to the first main surface. The porous portion includes a first porous portion having the first main surface and a second porous portion having the second main surface via the core portion. The first glossiness G of the first main surface at an incident angle of 20 degrees 1-1 and the second glossiness G of the second main surface at an incident angle of 20 degrees 1-2 At least one of the glossiness is G1.

15. The electrode foil for electrolytic capacitor according to claim 14, wherein The first glossiness G 1-1 With the second glossiness G 1-2 different.

16. An electrolytic capacitor, The electrolytic capacitor comprises a capacitor element, The capacitor element comprises a winding body and an electrolyte. The wound body is formed by winding an anode foil, a cathode foil, and a separator disposed between the anode foil and the cathode foil. The anode foil comprises: the electrode foil according to claim 1; and a dielectric layer covering a metal skeleton constituting the porous portion of the electrode foil.

17. The electrode foil for an electrolytic capacitor according to claim 16, wherein: The thickness of the dielectric layer is greater than 45 nm.

18. The electrolytic capacitor according to claim 16, wherein: The capacitor element includes a solid electrolyte as the electrolyte and may further include a liquid component. The solid electrolyte includes a conductive polymer.

19. The electrolytic capacitor according to claim 16, wherein: The main surface of the anode foil has a glossiness G2 of 10 or more at an incident angle of 20 degrees.

20. The electrolytic capacitor according to claim 19, wherein: The main surface of the anode foil includes a first main surface and a second main surface opposite to the first main surface. The porous portion includes a first porous portion having the first main surface and a second porous portion having the second main surface via the core portion. The dielectric layer includes: a first dielectric layer covering the metal skeleton constituting the first porous portion; and a second dielectric layer covering the metal skeleton constituting the second porous portion. The first glossiness G of the first main surface at an incident angle of 20 degrees 2-1 and the second glossiness G of the second main surface at an incident angle of 20 degrees 2-2 At least one of the glossiness is G2.

21. The electrolytic capacitor according to claim 20, wherein: The first glossiness G 2-1 Greater than the second glossiness G 2-2 , In the wound body, the anode foil is wound such that the first main surface faces the outer peripheral side of the wound body.

22. A method for manufacturing an electrode foil for an electrolytic capacitor, comprising: An etching step of etching a sheet containing a valve-acting metal to form porous portions on both main surfaces of the sheet; and The sheet after the etching process is compressed in the thickness direction to form the main surface having a glossiness G1 of 10 or more at an incident angle of 20 degrees.

23. The method for producing an electrode foil for an electrolytic capacitor according to claim 22, wherein: The glossiness G1 is 10 or more and 140 or less.

24. The method for producing an electrode foil for an electrolytic capacitor according to claim 22, wherein: The sheet includes Al.

25. The method for producing an electrode foil for an electrolytic capacitor according to claim 22, wherein: After the compression process, the thickness of the sheet is T A The thickness T of each single surface of the porous portion satisfies the following relationship: 90≤T A ≤200 and 25≤T≤(T A / 2)-10, T A The unit of is μm, and the unit of T is μm.

26. The method for producing an electrode foil for an electrolytic capacitor according to claim 22, wherein: In the etching process, the 2 Electrolytic etching was performed at the following current density.

27. The method for producing an electrode foil for an electrolytic capacitor according to claim 22, wherein: In the compression step, the thickness of the sheet is reduced by 5% or more and 40% or less.

28. The method for producing an electrode foil for an electrolytic capacitor according to claim 22, wherein: In the compression step, the sheet is conveyed between a pair of rollers and compressed.

29. The method for producing an electrode foil for an electrolytic capacitor according to claim 28, wherein: The sheet feeding speed is 0.5 m / min or more.

30. The method for producing an electrode foil for an electrolytic capacitor according to claim 28, wherein: When the roller is viewed from the direction of the rotation axis of the roller, the contact area between the roller and the sheet is in the shape of an arc. A central angle θ of the roller with respect to the arc of the contact region is greater than or equal to 0.15° and less than or equal to 1.5°.

31. The method for producing an electrode foil for an electrolytic capacitor according to claim 28, wherein: When a region obtained by projecting a contact region between the sheet and the roller onto a virtual plane parallel to the main surface of the sheet is defined as a projection region, A length L of the projection area in the conveyance direction of the sheet is greater than or equal to 0.5 mm and less than or equal to 5 mm.

32. The method for producing an electrode foil for an electrolytic capacitor according to claim 28, wherein: The sheet is compressed at a linear pressure of 0.55 kN / cm or more and 14 kN / cm or less.

33. The method for producing an electrode foil for an electrolytic capacitor according to claim 28, wherein: The thickness T0 of the porous portion of the sheet before compression and the diameter D of the roller satisfy the relationship of 380≤D / T0≤9800. The unit of T0 is mm, and the unit of D is mm.

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