JP2007039733A - Process for producing aluminum material for electrolytic capacitor electrode, aluminum material for electrolytic capacitor electrode, process for producing electrolytic capacitor electrode material, anode material for aluminum electrolytic capacitor, and aluminum electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing an aluminum material for an electrolytic capacitor electrode having excellent etching properties, in the production of an aluminum material for an electrolytic capacitor electrode where heating is performed in an oxidizing atmosphere after the completion of cold rolling and before final annealing, which solves the problem that the etching properties of the aluminum material after the final annealing are insufficient since the contents of Pb and Cu are not optimized; to also provide an aluminum material for an electrolytic capacitor electrode, a process for producing an electrolytic capacitor electrode material, an anode material for an aluminum electrolytic capacitor, and an aluminum electrolytic capacitor. <P>SOLUTION: In the production of an aluminum material for an electrolytic capacitor electrode, the content of Pb in an aluminum material is controlled to 0.3 to 2.5 ppm by mass, a tensile strain is applied instead of finish cold rolling, and the aluminum material before the application of the tensile strain and before final annealing is heated in an oxidizing atmosphere. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  In this specification, the term “aluminum” is used to include alloys thereof, and aluminum materials include foils and plates and molded bodies using these.

  An aluminum material that is generally used as an electrode material for an aluminum electrolytic capacitor is subjected to electrochemical or chemical etching treatment to increase the effective area of the aluminum material for the purpose of increasing the capacitance.

  In the manufacture of aluminum materials for electrolytic capacitor anodes that generate tunnel-like pits by direct current etching, in order to develop a cubic texture of aluminum, intermediate annealing is performed during the cold rolling process, and finish cold rolling ( After performing low-pressure rolling (low-rate rolling), final annealing is generally performed at a temperature of about 500 ° C. in an inert atmosphere or vacuum (for example, Patent Document 1). Moreover, as described in Patent Document 2, an aluminum cubic texture can be developed also by applying tensile strain to an aluminum material instead of finish cold rolling.

  Since the characteristics of the oxide film on the surface of the aluminum material after the final annealing are particularly related to the formation of pits at the initial stage of electrolytic etching, studies on the oxidation treatment on the surface of the aluminum material are being conducted. Trace elements contained in the aluminum material also affect the etching characteristics of the aluminum material. In particular, it is important to optimize the content of Pb because it concentrates on the surface layer of the aluminum material during the final annealing and activates the surface layer, and Cu affects the amount of dissolution of the aluminum material during electrolytic etching.

  Patent Document 3 includes a step of removing the surface layer of the aluminum foil, a step of heat oxidation under the conditions of temperature: 40 to 350 ° C., dew point: 0 to 80 ° C., time: 30 to 1800 seconds after the removal, and heating. It is disclosed that, after the oxidation, the oxide film on the surface layer of the aluminum foil after annealing can be thinned by carrying out the step of annealing in a non-oxidizing atmosphere, and quickly dissolved and removed in the etching solution. .

  In Patent Document 4, after the aluminum foil unwound from the coil is continuously washed to remove the oxide film, the surface of the aluminum foil is continuously oxidized by bringing it into contact with an (oxidizing) atmosphere, and then high temperature is applied. A method for producing an aluminum material for electrolytic capacitor electrodes, characterized by heat treatment, is described.

  In Patent Document 5, after removing the surface layer of the aluminum foil after the foil rolling, an oxide film having a thickness of 5 to 50 Å is formed on the surface of the aluminum foil while the average cell or subgrain size is 10 μm or less. There is disclosed a method for producing an aluminum material for electrolytic capacitor electrodes, characterized by undergoing a step of forming a high temperature heat treatment in a range in which the total thickness of the oxide film does not exceed 70 angstroms.

  Patent Document 6 describes a method for producing an aluminum material for electrolytic capacitor electrodes, which includes a step of heating an aluminum material by contact with a heating body.

  Patent Document 7 discloses a method of oxidizing in the air after the final annealing in an inert atmosphere in the production of an aluminum material for electrolytic capacitor electrodes.

Patent Document 8 describes the concentrations of Cu and Pb.
Japanese Patent Publication No.54-11242 WO 2004/003248 A1 JP-A-7-201673 Japanese Patent Laid-Open No. 4-127412 Japanese Patent Laid-Open No. 3-122260 WO03 / 091482 A1 JP-A-2-254140 Japanese Unexamined Patent Publication No. 2000-239773

  However, Patent Document 1 and Patent Document 2 do not have provisions regarding Pb and Cu contents, and there is no description of heating in an oxidizing atmosphere after finish cold rolling or after applying tensile strain and before final annealing.

  Further, in Patent Documents 3 to 6, although the capacitance is improved by heating in an oxidizing atmosphere or contact with a heating body, there is no description regarding the content of trace elements contained in the aluminum material. Further, Patent Document 7 also does not describe trace elements, and since the oxidation treatment is performed after the final annealing, there is a possibility that the etching characteristics improvement due to the oxidation treatment may be insufficient as compared with the case where the oxidation treatment is performed before the final annealing.

  In Patent Document 8, although the concentrations of Pb and Cu are prescribed, heating in an oxidizing atmosphere is not performed, and the etching characteristics of the aluminum material after the final annealing are not sufficiently improved.

  The present invention has been made in view of such a technical background, and in manufacturing an aluminum material for electrolytic capacitor electrodes in which heating is performed in an oxidizing atmosphere after the end of cold rolling and before final annealing, By appropriately controlling the element content, the problem of insufficient etching characteristics of the aluminum material after final annealing was solved, and a method for producing an aluminum material for electrolytic capacitor electrodes with excellent etching characteristics was provided. Furthermore, it is an object to provide an aluminum material for an electrolytic capacitor electrode, a method for producing an electrode material for an electrolytic capacitor, an anode material for an aluminum electrolytic capacitor, and an aluminum electrolytic capacitor.

In order to solve the above problems, the present invention provides the following means.
(1) An aluminum capacitor is subjected to hot rolling and cold rolling, and then subjected to intermediate annealing. After the intermediate annealing, until final annealing is started, tensile strain is applied, and final annealing is performed to provide an electrolytic capacitor electrode. When the aluminum material for manufacturing is manufactured, the aluminum material contains 0.3 mass ppm or more and 2.5 mass ppm or less of Pb, and the aluminum material after applying the tensile strain and before the final annealing is heated in an oxidizing atmosphere. A method for producing an aluminum material for electrolytic capacitor electrodes, which is characterized.
(2) The method for producing an aluminum material for electrolytic capacitor electrodes as recited in the aforementioned Item 1, wherein the aluminum material contains 10 mass ppm or more and 150 mass ppm or less of Cu.
(3) The method for producing an aluminum material for electrolytic capacitor electrodes as described in (1) or (2) above, wherein the aluminum purity of the aluminum material is 99.9% by mass or more.
(4) The method for producing an aluminum material for electrolytic capacitor electrodes as described in any one of 1 to 3 above, wherein the heating temperature in an oxidizing atmosphere is 50 to 400 ° C.
(5) The method for producing an aluminum material for electrolytic capacitor electrodes as described in 4 above, wherein the heating time in the oxidizing atmosphere is 3 seconds or more and 72 hours or less.
(6) The method for producing an aluminum material for electrolytic capacitor electrodes as described in any one of 1 to 5 above, wherein the oxygen concentration in the oxidizing atmosphere is 0.1% by volume or more.
(7) The method for producing an aluminum material for electrolytic capacitor electrodes as recited in any one of the aforementioned Items 1 to 6, wherein the cleaning is performed before the heating in the oxidizing atmosphere after applying the tensile strain.
(8) The manufacturing of the aluminum material for electrolytic capacitor electrodes as described in (7) above, wherein the cleaning liquid used for cleaning is at least one of an organic solvent, water to which a surfactant is added, and a mixture of a water-soluble organic solvent and water. Method.
(9) The method for producing an aluminum material for electrolytic capacitor electrodes as recited in the aforementioned Item 7, wherein the cleaning liquid used for cleaning is at least one of an acidic aqueous solution and an alkaline aqueous solution.
(10) The method for producing an aluminum material for electrolytic capacitor electrodes as recited in the aforementioned Item 7, wherein the cleaning is performed by sequential execution of cleaning with an alkaline aqueous solution and cleaning with an acidic aqueous solution.
(11) The aluminum material for an electrolytic capacitor electrode according to (9) or (10), wherein the acid in the acidic aqueous solution is one or more selected from acids containing hydrochloric acid, sulfuric acid, nitric acid, and phosphorus element. Production method.
(12) The preceding item 9 or the preceding item, wherein the alkali is one or more selected from sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium orthosilicate, sodium metasilicate, trisodium phosphate and sodium carbonate 10. The method for producing an aluminum material for electrolytic capacitor electrodes according to 10.
(13) The electrolysis according to any one of items 9 to 12, wherein an average removal amount of the aluminum material surface layer by cleaning is 1 nm or more and 500 nm or less per one side of the aluminum material at a removal amount D (nm) specified below. Manufacturing method of aluminum material for capacitor electrode.

Removal amount D (nm) = E (g / cm ² ) x 10 ⁷ /2.7 (g / cm ³ )
Where E is the weight loss per unit surface area due to cleaning
2.7 g / cm ³ is the density of the aluminum material (14) After applying the tensile strain, heating in an oxidizing atmosphere without performing cleaning is performed for the electrolytic capacitor electrode according to any one of the preceding items 1 to 6 Manufacturing method of aluminum material.
(15) The method for producing an aluminum material for electrolytic capacitor electrodes as described in (8) or (14) above, wherein the Pb concentration in the aluminum material is 0.6 mass ppm or more and 2.5 mass ppm or less.
(16) The method for producing an aluminum material for electrolytic capacitor electrodes as described in any one of 1 to 15 above, wherein the final annealing is performed in an inert gas atmosphere.
(17) The method for producing an aluminum material for electrolytic capacitor electrodes as recited in any one of the aforementioned Items 1 to 16, wherein the final annealing is performed at a temperature of 450 ° C. or more and 600 ° C. or less.
(18) An aluminum material for electrolytic capacitor electrodes produced by the production method according to any one of items 1 to 17 above.
(19) The aluminum material for electrolytic capacitor electrodes as described in 18 above, which is used as an anode material for medium pressure or an anode material for high pressure.
(20) A method for producing an electrode material for an electrolytic capacitor, comprising performing etching on an aluminum material produced by the production method according to any one of items 1 to 17 above.
(21) The method for producing an electrode material for electrolytic capacitors as described in 20 above, wherein at least part of the etching is direct current electrolytic etching.
(22) The method for producing an electrode material for electrolytic capacitors as described in 21 above, wherein the chemical conversion treatment is performed after the etching.
(23) An anode material for an aluminum electrolytic capacitor produced by the production method according to item 21 or 22 above.
(24) An aluminum electrolytic capacitor characterized in that an aluminum electrode material produced by the production method according to any one of items 20 to 22 is used as an electrode material.

  According to the invention according to the preceding paragraph (1), hot rolling and cold rolling are performed on the aluminum material, then intermediate annealing is performed, and after the intermediate annealing, until final annealing is started, tensile strain is applied, When manufacturing aluminum material for electrolytic capacitor electrodes by applying final annealing, the aluminum material contains 0.3 mass ppm or more and 2.5 mass ppm or less of Pb, and the aluminum material after applying tensile strain and before final annealing is oxidizing Since it heats in atmosphere, the aluminum material for electrolytic capacitor electrodes excellent in the etching characteristic in which the solubility of the aluminum material surface layer at the time of etching is uniform can be obtained.

  According to the invention according to item (2) above, since the aluminum material contains 10 mass ppm or more and 150 mass ppm or less of Cu, an aluminum material for electrolytic capacitor electrodes excellent in etching characteristics can be obtained.

  According to the invention relating to item (3) above, since the aluminum purity of the aluminum material is 99.9% by mass or more, it is possible to prevent deterioration of etching characteristics due to impurities.

  According to the invention according to item (4) above, since the heating temperature in the oxidizing atmosphere is 50 to 400 ° C., the solubility of the aluminum material surface layer becomes uniform when the aluminum material after the final annealing is etched. .

  According to the invention according to item (5) above, since the heating time in the oxidizing atmosphere is 3 seconds or more and 72 hours or less, the solubility of the aluminum material surface layer is uniform when the aluminum material after the final annealing is etched. become.

  According to the invention according to item (6) above, since the oxygen concentration in the oxidizing atmosphere is 0.1% by volume or more, the solubility of the aluminum material surface layer becomes uniform when the aluminum material after the final annealing is etched.

  According to the invention according to the item (7), since cleaning is performed after applying tensile strain and before heating in an oxidizing atmosphere, an aluminum material for an electrolytic capacitor electrode having a clean surface and better etching characteristics is obtained. be able to.

  According to the invention according to item (8) above, the cleaning liquid used for cleaning is at least one of an organic solvent, water to which a surfactant is added, and a mixture of a water-soluble organic solvent and water. be able to.

  According to the invention according to item (9), since the cleaning liquid used for cleaning is at least one of an acidic aqueous solution and an alkaline aqueous solution, cleaning can be performed more reliably.

  According to the invention according to item (10) above, cleaning is performed by sequential execution of cleaning with an alkaline aqueous solution and cleaning with an acidic aqueous solution, so that cleaning can be performed more reliably.

  According to the invention according to item (11) above, the acid in the acidic aqueous solution is one or more selected from hydrochloric acid, sulfuric acid, nitric acid, and an acid containing phosphorus element. It can be carried out.

  According to the invention according to item (12), the alkali is one or two selected from sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium orthosilicate, sodium metasilicate, trisodium phosphate, and sodium carbonate. Since it is more than seeds, cleaning can be performed more reliably.

  According to the invention of the preceding item (13), since the average removal amount D (nm) of the aluminum material surface layer by cleaning is 1 nm or more and 500 nm or less per one side of the aluminum material, the aluminum when the aluminum material after the final annealing is etched The solubility of the material surface layer becomes uniform.

  According to the invention according to the preceding item (14), even if cleaning is not performed after heating in an oxidizing atmosphere after applying tensile strain, the etching characteristics are excellent because there is no adhesion of a large amount of oil after applying applied strain. An aluminum material for electrolytic capacitor electrodes can be obtained.

  According to the invention according to the item (15), an organic solvent is used as a cleaning agent when cleaning is not performed before heating in an oxidizing atmosphere after applying tensile strain or before heating in an oxidizing atmosphere after applying tensile strain. In the case of cleaning using at least one of water to which a surfactant is added and a mixture of a water-soluble organic solvent and water, the Pb concentration in the aluminum material is 0.6 mass ppm to 2.5 mass ppm, The solubility of the aluminum material surface layer when etching the aluminum material after the final annealing becomes more uniform.

  According to the invention according to item (16), since the final annealing is performed in an inert gas atmosphere, an increase in the thickness of the oxide film more than necessary can be suppressed, and an electrolytic capacitor electrode excellent in etching characteristics Aluminum material can be obtained.

  According to the invention according to item (17), since the final annealing is performed at a temperature of 450 ° C. or higher and 600 ° C. or lower, an aluminum material for electrolytic capacitor electrodes in which etch pits are uniformly generated can be obtained.

  According to the invention according to item (18) above, the aluminum material for electrolytic capacitor electrodes having excellent etching characteristics can be obtained.

  According to the invention of the previous item (19), it can be an anode material for medium pressure or high pressure excellent in etching characteristics.

  According to the invention of the preceding item (20), an electrode material for an electrolytic capacitor having a large capacitance can be manufactured by etching.

  According to the invention of the preceding item (21), a large number of deep and thick tunnel-like pits can be generated by performing at least a part of etching by DC electrolytic etching, and oxidation before final annealing after applying the tensile strain. The effect of heating in a sexual atmosphere can be efficiently exhibited.

  According to the invention of the preceding item (22), the chemical conversion treatment is performed after the etching, so that an electrode material for an electrolytic capacitor suitable as an anode material can be obtained.

  According to the invention which concerns on previous term (23), it can be set as the anode material for aluminum electrolytic capacitors with a high electrostatic capacity.

  According to the invention of the previous item (24), an aluminum electrolytic capacitor having a high capacitance can be obtained.

  The inventor of the present invention sequentially performs hot rolling, cold rolling, intermediate annealing, and imparting tensile strain to an aluminum material containing 0.3 mass ppm to 2.5 mass ppm of Pb, and finally anneals the aluminum material for electrolytic capacitor electrodes. In manufacturing, heating the aluminum material in an oxidizing atmosphere after imparting tensile strain and before final annealing makes the solubility of the aluminum material surface layer uniform when etching the aluminum material after final annealing, and the electrolytic etching characteristics Found to improve.

  Below, the manufacturing method of the aluminum material for electrolytic capacitor electrodes is demonstrated in detail.

  The aluminum purity of the aluminum material is not particularly limited as long as it is within the range used for an electrolytic capacitor, but it is preferably 99.9% by mass or more, particularly preferably 99.95% by mass or more. In the present invention, for the sake of convenience, the aluminum purity of the aluminum material is a value obtained by subtracting the total concentration (mass%) of Fe, Si and Cu from 100 mass%.

  In this specification, “mass ppm” may be used in addition to “mass%”. In this case, 1% by mass is 10,000 ppm by mass.

  Pb is concentrated on the surface of the aluminum material at the time of final annealing and greatly affects the formation of etch pits. When tunnel-like etch pits are generated by a direct current etching method, if Pb is too small, etch pit dispersibility is poor, and if it is too large, surface dissolution of the aluminum material increases. In the present application, the Pb concentration is defined as 0.3 mass ppm or more and 2.5 mass ppm or less in order to exert the effect of improving the etching characteristics by heating the aluminum material in the oxidizing atmosphere after the final strain after the tensile strain.

  Further, in order to further improve the dispersibility of the etch pit, it is preferable that Cu is contained in an amount of 10 mass ppm to 150 mass ppm. If the Cu content is less than 10 ppm by mass, the effect of improving the etch pit dispersibility is poor, and if it exceeds 150 ppm by mass, the dissolution loss of the aluminum material during electrolytic etching increases and the capacitance decreases. Further, the Cu content is preferably 15 ppm or more and 100 ppm or less.

  The production process of the aluminum material is not limited, but is performed in the order of adjustment of the melting component of the aluminum material, slab casting, hot rolling, cold rolling, intermediate annealing, imparting tensile strain, heating in an oxidizing atmosphere, and final annealing. The In addition, you may implement washing | cleaning before the heating in an oxidizing atmosphere after provision of a tensile strain.

  The application of tensile strain is a process performed for controlling the cube orientation in combination with intermediate annealing. Since there is no problem that a large amount of lubricating oil adheres to the surface of the aluminum material as in the case of finish cold rolling, the tensile strain is imparted without the need for cleaning before heating in an oxidizing atmosphere after imparting tensile strain. It is easy to oxidize the surface layer of the aluminum material by heating in the atmosphere. Further, imparting tensile strain has the advantage that even if the aluminum material is thicker than finish cold rolling, the aluminum crystal grains are likely to be coarsened during the final annealing, and a thick aluminum material is easy to manufacture. The method for imparting tensile strain is not particularly limited, but the method described in WO2004 / 003248 A1 can be applied.

  The tensile strain applied after the intermediate annealing is preferably 1% or more and 15% or less. If the tensile strain is less than 1%, the processing strain for preferential growth of crystal grains having a cubic orientation is insufficient, and if it exceeds 15%, the aluminum material may break during the tensile process. The tensile strain may be applied to the aluminum material by uniaxial tension that imparts tensile strain in one direction, for example, only in the length direction, or biaxial that imparts tensile strain in two different directions, for example, the length direction and the width direction. It may be by tension. Further, the aluminum material may be bent and deformed to generate tensile strain.

  As the cleaning liquid used for cleaning the aluminum material, an organic solvent, water to which a surfactant is added, an alkaline aqueous solution, or an acidic aqueous solution can be used. A mixture of a water-soluble organic solvent and water may also be used.

  When the aluminum material surface layer is removed by washing, at least one of an alkaline aqueous solution and an acidic aqueous solution is used. Cleaning may be performed using a single cleaning solution, or may be performed using an acidic aqueous solution after being performed using an alkaline aqueous solution.

  The content of Pb in the aluminum material when the aluminum material surface layer is removed by washing using at least one of an alkaline aqueous solution and an acidic aqueous solution may be 0.3 mass ppm or more and 2.5 mass ppm or less, which is the range of the present invention. . If the Pb content is less than 0.3 mass ppm, the etch pit dispersibility is poor, and if it exceeds 2.5 mass ppm, the surface dissolution of the aluminum material increases and the capacitance decreases. Further, the Pb content is preferably 0.4 mass ppm or more and 1.8 mass ppm or less, and particularly preferably 0.5 mass ppm or more and 1.2 mass ppm or less.

  When cleaning with at least one of organic solvent, water with added surfactant, and a mixture of water-soluble organic solvent and water, or before heating in an oxidizing atmosphere after applying tensile strain In this case, the Pb content is preferably 0.6 mass ppm or more and 2.5 mass ppm or less. If the Pb content is less than 0.6 mass ppm, the etch pit dispersibility is poor, and if it exceeds 2.5 mass ppm, the surface dissolution of the aluminum material increases and the capacitance decreases. Further, the Pb content is preferably 0.7 mass ppm or more and 1.8 mass ppm or less, particularly preferably 0.7 mass ppm or more and 1.2 mass ppm or less.

  The organic solvent used for washing is not particularly limited, but examples include alcohols, diols, aromatic hydrocarbons such as toluene and xylene, alkane hydrocarbons, cyclohexane, ketones, ethers, esters, petroleum products, etc. It is done.

Examples of the alcohol include methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), 1-propanol (CH ₃ CH ₂ CH ₂ OH), 2-propanol (CH ₃ CH (OH) CH ₃ ), 1-butanol (CH ₃ CH ₂ CH ₂ CH ₂ OH), 2-butanol (CH ₃ CH ₂ CH (OH) CH ₃ ), 1-pentanol (CH ₃ CH ₂ CH ₂ CH ₂ CH ₂ OH), 2 -Pentanol (CH ₃ CH ₂ CH ₂ CH (OH) CH ₃ ) and the like are mentioned, and those represented by C _n H _{2n + 1} OH (n = 1 to 10 natural number) are preferred. Moreover, alicyclic compounds, such as cyclohexanol, can also be used as alcohol.

Examples of the diol include 1,2-ethanediol (HOCH ₂ CH ₂ OH), 1,2-propanediol (CH ₃ CH (OH) CH ₂ OH), 1,3-propanediol (HOCH ₂ CH ₂ CH ₂ OH).

Examples of the alkane hydrocarbons include pentane (C ₅ H ₁₂ ), hexane (C ₆ H ₁₄ ), heptane (C ₇ H ₁₆ ), octane (C ₈ H ₁₈ ), nonane (C ₉ H ₂₀ ), decane (C ₁₀ H ₂₂₎ which like is represented by C _n H _{2n + 2} include (a natural number of n = 5 to 15) are preferred. Moreover, application of alicyclic hydrocarbons such as cyclohexane is also possible.

Examples of the ketone include acetone (CH ₃ COCH ₃ ), 2-butanone (CH ₃ COC ₂ H ₅ ), 3-pentanone (CH ₃ CH ₂ COCH ₂ CH ₃ ), 3-methyl-2-butanone (CH ₃ COCH (CH ₃ ) ₂ ) and the like can be exemplified, and those represented by R1COR2 (R1 and R2: aliphatic hydrocarbon groups, and the total number of carbon atoms of R1 and R2 is 8 or less) are preferable. Further, a cyclic ketone such as cyclohexanone (C ₆ H ₁₀ O) may be used.

Examples of the ether include a substance represented by R1-O—R2 (R1 and R2: aliphatic hydrocarbon groups, and the total number of carbon atoms of R1 and R2 is 8 or less), 2-methoxyethanol (CH ₃ OCH ₂ CH ₂ OH), 2-ethoxyethanol (CH ₃ CH ₂ OCH ₂ CH ₂ OH), 2-butoxyethanol (CH ₃ CH ₂ CH ₂ CH ₂ OCH ₂ CH ₂ OH) 2- (2-ethoxy) ethoxy Also included are glycol ethers such as ethanol (CH ₃ CH ₂ OCH ₂ CH ₂ OCH ₂ CH ₂ OH).

Examples of the ester include acetate represented by CH ₃ COOR (R: an aliphatic hydrocarbon group having 1 to 5 carbon atoms).

  Examples of petroleum products include industrial gasoline (JIS K 2201), automotive gasoline (JIS K 2202), aviation gasoline (JIS K 2206), kerosene (JIS K 2203), light oil (JIS K 2204), petroleum ether (JIS K 8593), petroleum benzine (JIS K 8594), ligroin (JIS K 8937), kerosene and the like.

  In addition, as an organic solvent which can be used by mixing with water, methanol, ethanol, propanol, acetone, etc. are mentioned among the said organic solvents.

  The surfactant contained in the solution obtained by adding a surfactant to the water used for washing is not particularly limited, but anionic surfactants, cationic surfactants, and nonionic surfactants can be used. .

  As the anionic surfactant, sulfate ester salts and sulfonate salts can be used.

As the sulfate ester salt, R-OSO ₃ Na (R = saturated hydrocarbon group having 8 to 18 carbon atoms or unsaturated hydrocarbon group having one double bond) can be used, specifically sodium dodecyl sulfate. (C ₁₂ H ₂₅ OSO ₃ Na), sodium hexadecyl sulfate (C ₁₆ H ₃₃ OSO ₃ Na), sodium stearyl sulfate (C ₁₈ H ₃₇ OSO ₃ Na), sodium oleyl sulfate (C ₁₈ H ₃₅ OSO ₃ Na), etc. It can be illustrated.

The sulfonate is R-SO ₃ Na (R = saturated hydrocarbon group having 8 to 18 carbon atoms or unsaturated hydrocarbon group having one double bond) or sodium dodecylbenzenesulfonate (C ₁₂ H ₂₅ -C ₆ H ₄ -SO ₃ Na) and other R-SO ₃ Na (R: an alkylbenzyl group in which the alkyl group is a saturated hydrocarbon group having 8 to 14 carbon atoms or an unsaturated hydrocarbon group having one double bond) Can be used.

As a cationic surfactant, a quaternary ammonium salt represented by RN ⁺ (CH ₃ ) ₃ · Cl ⁻ (R = saturated hydrocarbon group having 8 to 16 carbon atoms) can be used.

As a nonionic surfactant, RO-(-CH ₂ CH ₂ O) _n H (R = saturated hydrocarbon group having 8 to 16 carbon atoms or unsaturated hydrocarbon group having one double bond, n = 6 -14) or _{RO - (- CH 2 CH 2} O) n H (R = alkyl group is an alkyl phenyl group which is unsaturated hydrocarbon group having one saturated hydrocarbon group or a double bond having 8 to 12 carbon atoms , N = 6 to 14), and a polyethylene glycol type nonionic surfactant can be exemplified. In addition, what has more n than the said range may be contained in the nonionic surfactant by the molar ratio of 50% or less.

  At least one of the above surfactants can be added to water and used as a cleaning liquid. A surfactant having a surfactant whose carbon number is less than the above range may be added in a molar ratio of 50% or less. In addition, when an anionic surfactant and a cationic surfactant are mixed in water, a precipitate is generated. Therefore, it is preferable to avoid mixing.

  The addition concentration of the surfactant is not particularly defined, but is preferably not less than the critical micelle concentration in order to exert a cleaning effect.

  Examples of the alkali in the alkaline aqueous solution used for washing include sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium orthosilicate, sodium metasilicate, trisodium phosphate, and sodium carbonate, and were selected from these alkalis. One or more types can be dissolved in water and used as a cleaning solution.

  As the acid in the acidic aqueous solution used for washing, one or more selected from acids containing hydrochloric acid, sulfuric acid, nitric acid, and phosphorus elements are used. Examples of the acid containing phosphorus element include orthophosphoric acid (hereinafter referred to as phosphoric acid), pyrophosphoric acid, metaphosphoric acid, and polyphosphoric acid. Perchloric acid and hypochlorous acid may also be used.

  The surface layer removal amount of the aluminum material by the alkaline aqueous solution or the acidic aqueous solution is adjusted by adjusting the alkali or acid concentration, the temperature of the alkaline or acidic aqueous solution, and the contact time between the aluminum material and the alkaline or acidic aqueous solution. . Further, a surfactant or chelating agent may be added to the cleaning liquid for the purpose of enhancing the cleaning effect of the aluminum material surface layer.

  The removal amount of the aluminum material surface layer by the cleaning is an average value, and is preferably 1 nm or more and 500 nm or less per one side of the aluminum material. If the removal amount of the surface layer is less than 1 nm, the removal of the oxide film on the surface layer of the aluminum material may be insufficient, and if the surface layer is removed more than 500 nm, the formation of etch pit nuclei on the surface layer of the aluminum material is suppressed, and etching is performed instead The characteristics are poor and the capacitance may decrease. A particularly preferable surface layer removal amount by washing is 1.5 nm or more and 200 nm or less, further preferably 5 nm or more and 200 nm or less, and more preferably 10 nm or more and 150 nm or less.

The density of the aluminum surface layer oxide film and the metallic aluminum is different, but in this application the surface layer removal amount D (nm) of the aluminum material is the mass loss E (g / cm ² ) per unit surface area due to cleaning and the aluminum Using a density of 2.7 g / cm ³ , D (nm) = E × 10 ⁷ /2.7 is specified.

  A method for contacting the cleaning liquid with the aluminum material is not particularly limited, and examples include immersion, contact of the aluminum material with the surface of the cleaning liquid, and spraying.

  The heating method in the oxidizing atmosphere is not limited, and examples thereof include blast heating and radiation heating. Moreover, the form of the aluminum material to be heated is not particularly limited, and batch heating may be performed in a state where the coil is wound around the coil, or winding may be performed after the coil is rewound and continuously heated.

  The heating temperature of the aluminum material in the oxidizing atmosphere is preferably 50 to 400 ° C. When the heating temperature is less than 50 ° C., the solubility of the aluminum material surface layer at the time of etching the aluminum material after the final annealing becomes non-uniform. When the heating temperature exceeds 400 ° C., the surface oxide film of the aluminum material becomes too thick, and the etching characteristics of the aluminum material after the final annealing deteriorate. The heating temperature of the particularly preferable aluminum material is 70 to 350 ° C.

  The heating time is preferably 3 seconds or more and 72 hours or less. If the heating time is less than 3 seconds, the solubility of the aluminum material surface layer becomes uneven during etching of the aluminum material after the final annealing, and if the heating time exceeds 72 hours, the dissolution uniformity of the aluminum material surface layer hardly changes. Cost increases due to energy consumption during heating. A particularly preferable heating time is 10 seconds to 48 hours, particularly 70 seconds to 48 hours.

Appropriate conditions for the heating temperature and time in the oxidizing atmosphere are selected depending on the heating method. For example, when the aluminum material is heated in the state of being wound as a coil, it is preferably heated at 50 ° C. to 280 ° C. for 30 minutes to 72 hours. In addition, the heating time t (hour) when heating the aluminum material with the coil unwound or cut into a sheet shape is 10 / (1.44 × x ^1.5 ) ≦ when the heating temperature is x (° C.). It is preferable that t ≦ 72, and more preferably 10 / (1.44 × x ^1.5 ) ≦ t ≦ 48.

  The oxygen concentration in the oxidizing atmosphere in heating the aluminum material in the oxidizing atmosphere is preferably 0.1% by volume or more. If the oxygen concentration is less than 0.1% by volume, the surface of the aluminum material may not be sufficiently oxidized during heating. The oxygen concentration is particularly preferably 1% by volume or more, particularly preferably 5% by volume or more, and air can be suitably used as the oxidizing atmosphere.

  The treatment atmosphere in the final annealing of the aluminum material is not particularly limited, but it is preferable to heat in an atmosphere with less moisture and oxygen so as not to increase the thickness of the oxide film. Specifically, it is preferable to heat in an inert gas such as argon or nitrogen or in a vacuum of 0.1 Pa or less. Moreover, hydrogen gas can also be suitably used as the atmosphere for final annealing.

  The cubic occupancy ratio of the aluminum material after the final annealing is preferably 90% or more.

  The method of final annealing is not particularly limited, and batch annealing may be performed in a state of being wound around the coil, and the coil may be rewound and continuously annealed, and then wound on the coil, and at least batch annealing and continuous annealing may be performed. Either one may be performed multiple times.

  Although the temperature and time during annealing are not particularly limited, for example, when performing batch annealing, it is preferable to perform annealing at 450 to 600 ° C. for 10 minutes to 50 hours. When the temperature is less than 450 ° C. and the time is less than 10 minutes, there is a possibility that a surface on which etch pits are uniformly generated cannot be obtained. On the other hand, when the annealing temperature exceeds 600 ° C., the aluminum material is likely to be adhered, and even if annealing is performed for more than 50 hours, the surface expansion effect by etching is saturated and the thermal energy cost is increased. In particular, it is preferably annealed at 460 to 570 ° C. for 20 minutes to 40 hours.

  Further, the rate of temperature rise / pattern is not particularly limited, and the temperature may be raised at a constant rate, or may be stepped up / cooled while repeating the temperature rise and temperature holding, and the temperature is 450 to 600 ° C. in the annealing process. What is necessary is just to anneal for a total of 10 minutes-50 hours in a temperature range.

  Processes and process conditions other than those specified in the present invention are not particularly limited, and may be performed according to a conventional method. Moreover, the manufacturing method of an aluminum material is changed suitably according to the relationship with the etching conditions of an aluminum material.

  The thickness of the aluminum material for electrolytic capacitor electrodes obtained after the final annealing is not particularly defined. Those having a thickness of 200 μm or less, referred to as foil, and those having a thickness larger than that are also included in the present invention.

  The aluminum material that has undergone final annealing is subjected to an etching process in order to improve the surface expansion ratio. Etching conditions are not particularly limited, but preferably a direct current etching method is employed. By the direct current etching method, the portion that becomes the nucleus of the etch pit promoted in the annealing is deeply and thickly etched to generate a large number of tunnel-like pits, thereby realizing a high capacitance.

  After the etching treatment, a chemical conversion treatment is preferably performed to obtain an anode material. In particular, it is preferably used as an electrolytic capacitor electrode material for medium pressure and high pressure, but it does not preclude use as a cathode material. Moreover, the electrolytic capacitor using this electrode material can realize a large capacitance.

  The capacitance may be measured in accordance with a conventional method. For example, a method of measuring a chemically treated etched foil at 120 Hz in an 80 g / L ammonium borate aqueous solution at 30 ° C. using a stainless steel plate as a counter electrode. It can be illustrated.

  Examples of the present invention and comparative examples are shown below.

  Aluminum slabs containing Fe, Si, Cu, and Pb listed in Table 1 were prepared. A sheet obtained by hot rolling an aluminum slab is cold-rolled to a thickness of 118 μm, annealed in a nitrogen atmosphere at 250 ° C. for 11 hours, and then given a tensile strain by uniaxial tension in the rolling direction. The aluminum material was 110 μm, width 500 mm, and length 2000 m. Table 2 shows the types of manufacturing steps of the aluminum material for electrolytic capacitor electrodes carried out after applying tensile strain (Step 1 to Step 3), Tables 3 to 5 show conditions for cleaning (Step 1) in Table 2, and Table 6 shows 2 shows the conditions for heating (step 2) in an oxidizing atmosphere.

The removal amount of the aluminum material surface layer is controlled by the immersion time in the cleaning liquid when the aluminum material surface layer is removed by washing with an alkaline aqueous solution, washing with an acidic aqueous solution, washing with an alkaline aqueous solution, and washing with an acidic aqueous solution sequentially. When the acid cleaning was performed after the alkali cleaning, the removal amount was controlled by controlling the immersion time in the alkali cleaning solution.
Example 1
Using the aluminum slab of composition 6 in Table 1, the above-described steps up to the application of tensile strain were carried out to obtain an aluminum material.

Next, the aluminum material was washed with a 20 mass% H ₂ SO ₄ aqueous solution at 80 ° C. as shown in Condition 29 in Table 5 to remove the surface layer of the aluminum material by 10 nm (Step 1). As shown in H4, the substrate was heated in air at 200 ° C. for 8 hours (step 2), and further subjected to final annealing in an argon atmosphere at 530 ° C. for 4 hours to obtain an aluminum material for electrolytic capacitor electrodes.
Examples 2 to 77, Comparative Examples 1 to 5
Aluminum slabs having various compositions shown in Tables 7 to 11 (specific compositions are shown in Table 1) were used, and the steps up to the application of tensile strain described above were performed to obtain aluminum materials.

  Next, each obtained aluminum material was processed on the conditions shown in Table 7-Table 11, and the aluminum material for electrolytic capacitor electrodes was obtained.

After immersing the aluminum material obtained in each of the above Examples and Comparative Examples in an aqueous solution containing HCl 1.0 mol / L and H ₂ SO ₄ 3.5 mol / L at a liquid temperature of 75 ° C., the current density was 0.2 A / cm ^2. The electrolytic treatment was applied. The aluminum material after the electrolytic treatment was further immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution having the above composition at 90 ° C. for 360 seconds to increase the pit diameter and obtain an etched foil. The obtained etched foil was subjected to chemical conversion treatment according to the EIAJ standard at a chemical conversion voltage of 270 V to obtain a sample for measuring capacitance.

  Tables 7 to 11 show relative capacitances when the capacitance of Comparative Example 1 is 100.

  As can be understood from the results in the above table, an aluminum material for electrolytic capacitors having excellent etching characteristics can be obtained by heating an aluminum material containing Pb in the concentration range defined in the present application in an oxidizing atmosphere and then annealing the aluminum material. Can do. In addition, the example in which the Cu content is 10 ppm or more and 150 ppm or less has a higher capacitance than the example in which the Cu content is less than 10 ppm or the Cu content is more than 150 ppm after heating in an oxidizing atmosphere and final annealing under the same conditions. high.

  On the other hand, since Comparative Example 1 does not carry out heating in an oxidizing atmosphere, the capacitance is lower than that of the Example. Since Comparative Example 2 performed heating in an oxidizing atmosphere, the capacitance was improved as compared with Comparative Example 3 in which heating was not performed in the oxidizing atmosphere, but Comparative Example 2 and Comparative Example 3 had a Pb content. Is less than 1 ppm, the capacitance is lower than in the examples. Further, Comparative Example 4 is less than the lower limit of Pb content application defined, Comparative Example 5 is lower both capacitance for exceeding the upper limit of the present provisions Pb content.

Claims (24)

Aluminum material for electrolytic capacitor electrodes is subjected to hot rolling and cold rolling on aluminum material, then subjected to intermediate annealing, and after the intermediate annealing until final annealing is started, tensile strain is applied, and final annealing is performed. In manufacturing
The aluminum material contains 0.3 mass ppm to 2.5 mass ppm of Pb,
A method for producing an aluminum material for electrolytic capacitor electrodes, comprising heating an aluminum material after applying tensile strain and before final annealing in an oxidizing atmosphere.   The method for producing an aluminum material for electrolytic capacitor electrodes according to claim 1, wherein the aluminum material contains 10 mass ppm or more and 150 mass ppm or less of Cu.   The method for producing an aluminum material for electrolytic capacitor electrodes according to claim 1 or 2, wherein the aluminum material has an aluminum purity of 99.9% by mass or more.   The method for producing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 3, wherein the heating temperature in an oxidizing atmosphere is 50 to 400 ° C.   The method for producing an aluminum material for electrolytic capacitor electrodes according to claim 4, wherein the heating time in the oxidizing atmosphere is 3 seconds or more and 72 hours or less.   The method for producing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 5, wherein the oxygen concentration in the oxidizing atmosphere is 0.1 vol% or more.   The method for producing an aluminum material for an electrolytic capacitor electrode according to any one of claims 1 to 6, wherein washing is performed after applying tensile strain and before heating in an oxidizing atmosphere.   The method for producing an aluminum material for electrolytic capacitor electrodes according to claim 7, wherein the cleaning liquid used for cleaning is at least one of an organic solvent, water to which a surfactant is added, and a mixture of a water-soluble organic solvent and water.   The method for producing an aluminum material for electrolytic capacitor electrodes according to claim 7, wherein the cleaning liquid used for cleaning is at least one of an acidic aqueous solution and an alkaline aqueous solution.   8. The method for producing an aluminum material for electrolytic capacitor electrodes according to claim 7, wherein the cleaning is performed by sequential execution of cleaning with an alkaline aqueous solution and cleaning with an acidic aqueous solution.   The production of the aluminum material for electrolytic capacitor electrodes according to claim 9 or 10, wherein the acid in the acidic aqueous solution is one or more selected from hydrochloric acid, sulfuric acid, nitric acid, and an acid containing phosphorus element. Method.   The alkali is one or more selected from sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium orthosilicate, sodium metasilicate, trisodium phosphate, and sodium carbonate. The manufacturing method of the aluminum material for electrolytic capacitor electrodes as described in any one of. The electrolytic capacitor according to any one of claims 9 to 12, wherein an average removal amount of the aluminum material surface layer by the cleaning is 1 nm or more and 500 nm or less per one surface of the aluminum material at a removal amount D (nm) specified below. Manufacturing method of aluminum material for electrodes.
Removal amount D (nm) = E (g / cm ² ) x 10 ⁷ /2.7 (g / cm ³ )
Where E is the weight loss per unit surface area due to cleaning
2.7 g / cm ³ is the density of aluminum material   The manufacturing method of the aluminum material for electrolytic capacitor electrodes of any one of Claim 1 thru | or 6 which heats in an oxidizing atmosphere, without implementing washing | cleaning after providing a tensile strain.   The method for producing an aluminum material for electrolytic capacitor electrodes according to claim 8 or 14, wherein the Pb concentration in the aluminum material is 0.6 mass ppm or more and 2.5 mass ppm or less.   The method for producing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 15, wherein the final annealing is performed in an inert gas atmosphere.   The method for producing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 16, wherein the final annealing is performed at a temperature of 450 ° C or higher and 600 ° C or lower.   The aluminum material for electrolytic capacitor electrodes manufactured by the manufacturing method of any one of Claims 1 thru | or 17.   The aluminum material for electrolytic capacitor electrodes according to claim 18, which is used as an anode material for medium pressure or an anode material for high pressure.   The manufacturing method of the electrode material for electrolytic capacitors characterized by etching to the aluminum material manufactured by the manufacturing method of any one of Claim 1 thru | or 17.   The method for producing an electrode material for an electrolytic capacitor according to claim 20, wherein at least a part of the etching is direct current electrolytic etching.   The method for producing an electrode material for an electrolytic capacitor according to claim 21, wherein a chemical conversion treatment is performed after the etching.   An anode material for an aluminum electrolytic capacitor produced by the production method according to claim 21 or 22. An aluminum electrolytic capacitor characterized in that an aluminum electrode material manufactured by the manufacturing method according to any one of claims 20 to 22 is used as an electrode material.