WO2005078751A1

WO2005078751A1 - Method of manufacturing aluminum material for electrolytic capacitor electrodes, aluminum material for electrolytic capacitor electrodes, anode material for aluminum electrolytic capacitors, and aluminum electrolytic capacitors

Info

Publication number: WO2005078751A1
Application number: PCT/JP2005/002968
Authority: WO
Inventors: Hideki Nishimori; Satoshi Hodzumi; Yutaka Kato
Original assignee: Showa Denko KK
Current assignee: Resonac Holdings Corp
Priority date: 2004-02-17
Filing date: 2005-02-17
Publication date: 2005-08-25
Anticipated expiration: 2006-08-17

Abstract

A method for manufacturing an aluminum material for electrolytic capacitor electrodes of the present invention, comprising the steps of heating an aluminum material in an oxidative atmosphere, removing the surface layer of the aluminum material by washing the heated aluminum material and subjecting the washed aluminum material obtained by washing to final annealing.

Description

DESCRIPTION

METHOD OF MANUFACTURING ALUMINUM MATERIAL FOR ELECTROLYTIC CAPACITOR ELECTRODES, ALUMINUM MATERIAL FOR ELECTROLYTIC

CAPACITOR ELECTRODES, ANODE MATERIAL FOR ALUMINUM ELECTROLYTIC CAPACITORS, AND ALUMINUM ELECTROLYTIC CAPACITORS

Priority is claimed to Japanese Patent Application No. 2004-040328, filed on February 17, 2004, Japanese Patent Application No.2004-304717, filed on October 19, 2004, Japanese Patent Application No.2004-316592, filed on October 29, 2004, Japanese Patent Application No.2004-348837, filed on December 1, 2004, Japanese Patent Application No.2004-377539, filed on December 27, 2004, U.S. Provisional Application No.60/614 ,328 , filed on September 30, 2004, U.S. Provisional Application No.60/621, 067, filed on October 25, 2004, and U.S. Provisional Application No.60/629, 971, filed on November 23, 2004, the disclosure of which are incorporated by reference in their entireties.

Cross Reference to Related Applications This application is an application filed under 35 U.S.C. §111 (a) claiming the benefit pursuant to 35 U.S.C. §119 (e)(1) of the filing date of Provisional Application No. 60/614,328, filed on September 30, 2004, U.S. Provisional Application No.60/621, 067, filed on October 25, 2004, and U.S. Provisional Application No.60/629, 971, filed on November 23, 2004 pursuant to 35 U.S.C.§lll(b) .

Technical Field The present invention relates to a method of manufacturing aluminum material for electrolytic capacitor electrodes , aluminum material for electrolytic capacitor electrodes, anode material for aluminum electrolytic capacitors, and aluminum electrolytic capacitors . In this description, the term "aluminum" is used as aluminum and alloys thereof, and aluminum material includes a foil, a plate, and products thereof .

Background Art Aluminum material generally used as electrode material for aluminum electrolytic capacitors is treated by an electrochemical, or a chemical etching to expand effective surface area of aluminum material in order to enhance capacitance. In manufacturing aluminum material for electrolytic capacitor anode, where tunnel structure pits are generated by direct current etching to grow cube texture of aluminum, in general, intermediate annealing is performed in mid-course of a cold rolling process, and after performing finish cold rolling (rolling with low reduction in thickness), aluminum material is subjected to final annealing at around 500° C in an inert atmosphere or in vacuum

(e.g. Patent Document 1). Moreover, as described in Patent Document 2, tensile strain application instead of finish cold rolling can also grow the cubic texture of aluminum. Etching characteristics of aluminum material obtained by final annealing depends greatly on the characteristics of aluminum prior to annealing. For the uniformity of the characteristics on the surface layer of aluminum material, therefore, it has been considering that aluminum is washed with aluminum soluble liquids in mid-course of cold rolling or after cold rolling. According to Patent Document 3 , after an aluminum plate in thickness (t) is reduced by cold rolling to a thickness satisfying

3.3 to ≤≥ t ≤≥ 20 to (to is a final thickness of aluminum), the

surface is washed and dissolved with alkaline aqueous solution or acid aqueous solution, subsequently is subjected to coldrolling. This method of manufacturing aluminum foil for electrolytic capacitors prevents the formation of a thick oxide layer. According to Patent Document 4 , is disclosed a method that makes an oxide layer on the surface of aluminum foil after annealing become thin, and also it dissolve and remove easily in an etching solution, by the method comprising: a process of removing a surface layer of aluminum foil; after the removing, a heat-oxidation process at a temperature of 40 to 350° C, a dew point of 0 to 80° C, for 30 to 1,800 sec; and after the heat-oxidation, an annealing process in a non-oxidative atmosphere. Also, as a means of removing the surface layer of aluminum foil, is disclosed washing with an alkaline solution such as sodium hydroxide or the like, and with an acid solution. Patent Document 5 describes a method of manufacturing aluminum foil for electrolytic capacitor electrodes, the method is that using a pure aluminum material of 99.96 to 99.98% in purity, intermediate annealing is performed at a temperature of 200 to 500° C , for not less than 1 hr, and in a course after the intermediate annealing before final annealing, the surface layer of aluminum foil is removed no less than 0.1 μm in a thickness direction. Patent Document 6 describes a method of manufacturing aluminum foil for electrolytic capacitor electrodes, the method is that cold rolled aluminum foil of 99.99% or more in purity, containing impurities for expanding effective surface area, is performed in a first step of annealing at a temperature of 250° C to 530° C, then the surface layer of aluminum foil is removed to give final annealing at higher than 500° C. According to Patent Document 6 , an average Fe content of aluminum foil surface layer having a ratio of less than 2.0 to that of inside may provide an aluminum foil for electrolytic capacitor electrodes to obtain capacitors with a large capacitance.

Patent Document 1: Japanese Examined Patent Publication No.11242

(1979)

Patent Document 2: WO 2004/ 003248 Al

Patent Document 3 : Japanese Unexamined Patent Publication

No.257137 (1991)

Patent Document 4: Japanese Unexamined Patent Publication No. 201673 ( 1995 )

Patent Document 5: Japanese Unexamined Patent Publication No. 81945 (1998)

Patent Document 6: Japanese Unexamined Patent Publication No. 210561 (2001)

However, when surface layer is removed chemically, because of unevenness in corrosion resistance of aluminum material surface prior to the removal of the surface layer, it is difficult to remove the surface layer uniformly, so that there has been a limit to enhance capacitance. By the technique described in Patent Document 3, because of the unevenness of aluminum material surface layer prior to washing, the aluminum material surface layer dissolves unevenly, it was insufficient to obtain improved etching characteristics of aluminum material after final annealing. By the technique described in Patent Document 4, although heat-oxidation prior to annealing contributes to the evenness of aluminum material surface layer, the characteristics of aluminum material surface layer prior to removing is uneven, thereby the surface after washing is affected, therefore it was insufficient to improve the evenness by the heat-oxidation and there was a limit to enhance the etching characteristics . Furthermore, characteristics of oxidized surface of aluminum material after intermediate annealing is changed by an atmosphere in the intermediate annealing, which affects greatly a surface layer removing afterwards, but there was no description on intermediate annealing atmosphere in the Patent Document 5. As well as a case of removing surface layer after intermediate annealing before finish cold rolling, in a case where surface layer is removed after performing sequentially intermediate annealing and finish cold rolling, since rolling reduction is lower in finish cold rolling than that in cold rolling prior to intermediate annealing, the atmosphere in the intermediate annealing affects greatly a solubility of surface layer by a chemical forming after the finish cold rolling. In Patent Document 6, there is no description on atmosphere in a first step of annealing before surface layer removing, no consideration is taken on such the method in the present invention that provides the uniform removing of the surface layer after being heated in an oxidative atmosphere. In the light of this technical background, the present invention was achieved to overcome the problem in the art, that is , in the conventional manufacturing method for aluminum material for electrolytic capacitor, upon solving the surface layer of aluminum material by washing, its dissolution is not uniform, and gives an insufficient etching characteristics of the aluminum material obtained after final annealing. It is an object of the present invention to provide a method of manufacturing aluminum material for electrolytic capacitor electrodes with excellent etching characteristics, aluminum material for electrolytic capacitor electrodes, a method of manufacturing electrode material for electrolytic capacitors, and aluminum electrolytic capacitors. Other objects of the present invention will become apparent from following embodiments of the present invention.

SUMMARY OF THE INVENTION In order to achieve the aforementioned objects, the present invention provides a following means : ( 1 ) A method for manufacturing an aluminum material for electrolytic capacitor electrodes including the steps of hot-rolling, cold-rolling and final annealing, comprising the steps of: heating an aluminum material in oxidative atmosphere after the hot-rolling and before commencing final annealing; removing the surface layer of the aluminum material by washing after the heating; and subjecting the washed aluminum material to the final annealing. (2) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to aforementioned Item 1, wherein heating of the aluminum material in oxidative atmosphere and removing of the surface layer by washing are conducted after finishing the cold-rolling. (3) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 1 or 2, wherein a cleaning liquid used for washing is an alkaline aqueous solution. (4) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 1 or 2, wherein the cleaning liquid used for washing is an acid.aqueous solution. (5) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Items 1 or 2 , wherein the aluminum material is sequentially washed by alkaline aqueous solution and by acid aqueous solution. (6) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Items 3 or 5, wherein an alkali in alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate (Na₃P0₄) and sodium carbonate. (7) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 4 or 5, wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphorus-containing acid. (8) The method, for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 1 to 7, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing after heating in the oxidative atmosphere is not less than 1 nm, and not more than 500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) xlO⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum. (9) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 1 to 8, wherein the heating temperature in the oxidative atmosphere is within the range of 50 to 400 °C. (10) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 9, wherein the heating time in the oxidative atmosphere is not less than 3 sec, and not more than 72 hr. (11) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 1 to 10, wherein the oxygen concentration in the oxidative atmosphere during heating is 0.1 volume % or more. (12) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 1 to 11, further comprising the step of degreasing the aluminum material before heating the aluminum material in the oxidative atmosphere, or after heating the aluminum material in the oxidative atmosphere before washing the surface layer of the aluminum material. (13) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 12, wherein the aluminum material is degreased by using an organic solvent. (14) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 12, wherein the aluminum material is degreased by using water added with a surfactant. (15) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 1, wherein the aluminum material is subjected to an intermediate annealing during the cold-rolling and subjected to finish cold-rolling after intermediate annealing; wherein the intermediate annealing is conducted in oxidative atmosphere, and the removing of the surface layer of the aluminum material by washing is conducted after intermediate annealing. (16) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 15, wherein the surface layer of the aluminum material is removed by washing the aluminum material after the finish cold-rolling before the final annealing. (17) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 15, wherein the surface layer, of the aluminum material is removed by washing the aluminum material after the intermediate annealing before the finish cold-rolling. (18) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 15 to 17, wherein the oxygen concentration in the oxidative atmosphere during the intermediate annealing is 0.1 volume % or more . (19) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 15 to 18, wherein the aluminum material is subjected to the intermediate annealing in oxidative atmosphere at a temperature not less than 200 °C, and not more than 320 °C. (20) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 15 to 19, wherein the cleaning liquid used for washing is alkaline aqueous solution. (21) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 15 to 19, wherein the cleaning liquid used for washing is acid aqueous solution. (22) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 15 to 19, wherein the aluminum material is sequentially washed by alkaline aqueous solution and acid aqueous solution. (23) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 20 to 22, wherein an alkali in alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate. (24) The methpd for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 21 or 22, wherein an acid in acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphorus-containing acid. (25) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 15 to 24, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing is not less than 1 nm, and not more than 500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) xlO⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum. (26) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 15 to 25, further comprising the step of degreasing the aluminum material after the cold-rolling before the intermediate annealing, before the final annealing. (27) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 26, wherein the aluminum material is degreased by using an organic solvent. (28) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 26, wherein the aluminum material is degreased by using water added with a surfactant. (29) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 1, wherein the aluminum material is subjected to an intermediate annealing during the cold-rolling and subjected to a finish cold-rolling after the intermediate annealing; wherein the intermediate annealing is conducted in an oxidative atmosphere, and the heating of the aluminum material in the oxidative atmosphere and the removing of the surface layer by washing are conducted after the finish cold-rolling. (30) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 29 , comprising the step of removing the surface of the aluminum material by washing the aluminum material after the intermediate annealing and before the finish cold-rolling. (31) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 29 or 30, wherein the cleaning liquid used for washing is the alkaline aqueous solution. (32) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 29 or 30, wherein the cleaning liquid used for washing is acid aqueous solution. (33) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 29 or 30, wherein the aluminum material is sequentially washed by alkaline aqueous solution and acid aqueous solution. (34) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 31 to 33, wherein an alkali in alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate. (35) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 32 or 33, wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulf ric acid, nitric acid and phosphorus-containing acid. (36) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 29 to 35, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing after heating in oxidative atmosphere after finish cold-rolling is not less than 1 nm, and not more than 500 n per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) xlO⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum. (37) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 29 to 36, wherein the heating temperature in the oxidative atmosphere after the finish cold-rolling is within the range of 50 to 400 °C. (38) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 37 , wherein the heating time in the oxidative atmosphere after the finish cold-rolling is not less than 3 sec, and not more than 72 hr. (39) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 29 to 38, wherein aluminum material is subjected to the intermediate annealing in the oxidative atmosphere at a temperature not less than 200 °C, and not more than 320 °C. (40) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 29 to 39, wherein the oxygen concentration in the oxidative atmosphere during heating after the finish cold-rolling is 0.1 volume % or more. (41) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 29 to 40, wherein the oxygen concentration in the oxidative atmosphere during the intermediate annealing is 0.1 volume % or more. (42) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 29 to 41, further comprising the step of degreasing the aluminum material before the intermediate annealing after the cold-rolling, before finally removing the surface layer of the aluminum material by washing the aluminum material. (43) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 42, wherein the aluminum material is degreased by using an organic solvent. (44) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 42, wherein the aluminum material is degreased by using water containing a surfactant . (45) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 1, wherein the aluminum material is subjected to an intermediate annealing after the cold-rolling and tensile-strained after the intermediate annealing and before commencing the final annealing; and the heating of the aluminum material in the oxidative atmosphere and the removing of the surface layer of the aluminum material by washing are conducted after giving the tensile strain. (46) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 45, wherein the cleaning liquid used for washing is the alkaline aqueous solution. (47) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 45, wherein the cleaning liquid used for washing is the acid aqueous solution . (48) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 45, wherein the aluminum material is sequentially washed by the alkaline aqueous solution and the acid aqueous solution. (49) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 46 to 48, wherein an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate. (50) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 47 or 48, wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuriσ acid, nitric acid and phosphorus-containing acid. (51) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 45 to 50, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing after heating in the oxidative atmosphere is not less than 1 nm, and not more than 500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) χl0⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum. (52) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 45 to 51, wherein the heating temperature in the oxidative atmosphere is within the range of 50 to 400 °C. (53) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 52, wherein the heating time in the oxidative atmosphere is not less than 3 sec, and not more than 72 hr. (54) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 45 to 53, wherein the oxygen concentration in the oxidative atmosphere during heating is 0.1 volume % or more. (55) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 1, wherein the aluminum material is subjected to an intermediate annealing in oxidative atmosphere after cold-rolling and tensile strained after the intermediate annealing and before commencing the final annealing; and the removing of the surface layer of the aluminum material by washing is conducted at least one time after the intermediate annealing. (56) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 55, wherein the surface layer of the aluminum material is removed by washing the aluminum material after the tensile strain application before the final annealing. (57) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 55, wherein the surface layer of the aluminum material is removed by washing the aluminum material after the intermediate annealing before the tensile strain application. (58) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items.55 to 57, wherein the surface layer of the aluminummaterial is removed bywashing the aluminummaterial after the tensile strain application before the final annealing, after heating the aluminum material in the oxidative atmosphere. (59) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 55 to 58, wherein the cleaning liquid used for washing is alkaline aqueous solution. (60) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 55 to 58, wherein the cleaning liquid used for washing is the acid aqueous solution. (61) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 55 to 58, wherein the aluminum material is sequentially washed by alkaline aqueous solution and acid aqueous solution. (62) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 59 to 61, wherein an alkali in alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate. (63) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 60 or 61, wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and a phosphor element. (64) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 55 to 63, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing after heating in the oxidative atmosphere after intermediate annealing is not less than 1 nm, and not more than

500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) ^χl0⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum. (65) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 57 to 64, wherein the heating temperature in the oxidative atmosphere after the tensile strain application is within the range of 50 to 400 "C. (66) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 65, wherein the heating time in the oxidative atmosphere after the tensile strain application is not less than 3 sec, and not more than 72 hr. (67) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 55 to 66, wherein the intermediate annealing in the oxidative atmosphere is performed at a temperature not less than 200 °C, and not more than 300 °C. (68) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 55 to 67, wherein the oxygen concentration in the oxidative atmosphere during heating after the tensile strain application is 0.1 volume % or more . (69) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 55 to 67, wherein the oxygen concentration in the oxidative atmosphere during the intermediate annealing is 0.1 volume % or more . (70) The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 1 to 69, wherein the aluminum material is subjected to the final annealing in inert gas atmosphere. (71) A method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 1 to 70, wherein the aluminum material is subjected to the final annealing at a temperature not less than 450 °C, and not more than 600 °C. (72) A method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of the aforementioned Items 1 to 71, wherein the aluminum purity of the aluminum material is 99.9 mass % or more. (73) The aluminum material for electrolytic capacitor electrodes manufactured by the method according to any one of the aforementioned Items 1 to 72. (74) The aluminum material for electrolytic capacitor electrodes according to the aforementioned Item 73, wherein the aluminum material is an anode material for middle or high voltages . (75) The method for manufacturing an electrode material for electrolytic capacitors, comprising the step of etching the aluminum material manufactured by any one of the aforementioned Items 1 to 72. (76) The method for manufacturing an electrode material for electrolytic capacitors according to the aforementioned Item 75, further comprising the step of performing formation of the dielectric by anodizing after etching. (77) The method for manufacturing an electrode material for electrolytic capacitors according to the aforementioned Item 75 or 76, wherein at least a part of the etching is DC electrolytic etching. (78) The anode material for aluminum electrolytic capacitors manufactured by the method according to any one of the aforementioned Items 75 to 77. (79) The aluminum electrolytic capacitor comprising the aluminum electrode material manufactured by the method according to any one of the aforementioned Items 75 to 77 as electrode materials .

The invention according to the aforementioned Item 1 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics by a method wherein aluminum material is heated in the oxidative atmosphere, thereafter, the surface layer of aluminum material is removed by washing, which can solve aluminummaterial uniformly upon washing, and then is subjected to final annealing. The invention according to the aforementioned Item 2 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics by amethod wherein after cold rolling, aluminum material is heated in oxidative atmosphere, thereafter, the surface layer of aluminum material is removed by washing, which can solve aluminum material uniformly upon washing, and is subjected to final annealing. The invention according to the aforementioned Item 3 provides that the surface layer of aluminum material can be removed reliably by washing because the cleaning liquid for washing is an alkaline aqueous solution. The invention according to the aforementioned Item 4 provides that the surface layer of aluminum material can be removed reliably by washing because the cleaning liquid for washing is an acid aqueous solution. The invention according to the aforementioned Item 5 provides that the surface layer of aluminum material can be removed reliably by washing because the washing is performed sequentially with an alkaline aqueous solution and an acid aqueous solution. The invention according to the aforementioned Item 6 provides that the surface layer can be removed more effectively because an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate (Na₃P0 ), and sodium carbonate . The invention according to the aforementioned Item 7 provides that the surface layer can be removed more effectively because an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, and phosphorus-containing acid. The invention according to the aforementioned Item 8 provides that an enhancement effect of capacitance can be surely obtained by uniform dissolution of aluminum material because the average removed amount of aluminum material surface layer by washing is not less than lnm, and not more than 500 nm per one side of aluminum material in the removed amount D (nm) . The invention according to the aforementioned Item 9 provides that while an excess thickening of oxide layer on aluminum material surface layer is suppressed, sufficient oxidization can be performed, then the surface layer can dissolve uniformly upon surface layer removing bywashing, because the heating temperature in the oxidative atmosphere is 50 to 400 °C. The invention according to the aforementioned Item 10 provides that while an excess thickening of oxide layer on aluminum material surface layer is suppressed, sufficient oxidization can be performed, then the surface layer can dissolve uniformly upon surface layer removing by washing, because the heating time is not less than 3 sec, and not more than 72 hr. The invention according to the aforementioned Item 11 provides that the surface layer of aluminum material can dissolve uniformly because the oxygen density of heating atmosphere in the oxidative atmosphere is not less than 0.1 volume%. The invention according to the aforementioned Item 12 provides aluminum material for electrolytic capacitor electrodes with better performances by a method where degreasing is performed before heating in the oxidative atmosphere, or before washing the surface layer of aluminum material after heating in the oxidative atmosphere, which can remove oils adhered to the surface layer of aluminum material. The invention according to the aforementioned Item 13 provides that degreasing can be performed reliably because the degreasing is performed with an organic solvent . The invention according to the aforementioned Item 14 i provides that degreasing can be performed reliably because the degreasing is performed with water containing a surfactant. The invention according to the aforementioned Item 15 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics resulting in a large capacitance by a method wherein the intermediate annealing is preformed in the oxidative atmosphere, and the surface layer of aluminum material is removed by washing in a process after the intermediate annealing prior to final annealing, which can solve aluminum material uniformly upon washing; and final annealing is preformed. The invention according to the aforementioned Item 16 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics resulting in a large capacitance by a method wherein the surface layer removing of aluminummaterial bywashing is performed after finish cold rolling before final annealing, which can solve aluminum material uniformly upon washing; and the final annealing is performed. The invention according to the aforementioned Item 17 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics resulting in a large capacitance by a method wherein the surface layer removing of aluminum material by washing is performed after intermediate annealing before finish cold rolling, which can solve aluminum material uniformly upon washing; and final annealing is performed. The invention according to the aforementioned Item 18 provides sufficient oxidization of aluminum material surface layer because the oxygen density of the oxidative atmosphere in intermediate annealing is not less than 0.1 volume% . The invention according to the aforementioned Item 19 provides aluminum material for electrolytic capacitor electrodes with a stable excellent etching characteristics by a method where the intermediate annealing is performed in the oxidative atmosphere at a temperature of not lower than 200° C, and not higher than 320° C, which allows a sufficient texture to grow preferentially recrystallized grain with a cubic orientation in final annealing. The invention according to the aforementioned Item 20 provides that the surface layer of aluminum material can be removed reliably by washing because the cleaning liquid for washing is an alkaline aqueous solution. The invention according to the aforementioned Item 21 provides that the surface layer of aluminum material can be removed reliably by washing because the cleaning liquid for washing is an acid aqueous solution. The invention according to the aforementioned Item 22 provides that the surface layer of aluminum material can be removed more reliably by washing because the washing is performed sequentially with an alkaline aqueous solution and an acid aqueous solution. The invention according to the aforementioned Item 23 provides that the surface layer can be removed more effectively because an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate. The invention according to the aforementioned Item 24 provides that the surface layer of aluminum can be removed more effectively because an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuriσ acid, nitric acid, and acids including phosphorous. The invention according to the aforementioned Item 25 provides that the enhancement effect of capacitance can be surely obtained by uniform dissolution of aluminum material because the average removed amount of aluminum material surface layer by washing is not less than lnm, and not more than 500 nm per one side of aluminum material. The invention according to the aforementioned Item 26 provides aluminum material for electrolytic capacitor electrodes with better performances by a method wherein the degreasing is performed, after cold rolling before intermediate annealing, in a process prior to final annealing, which can remove oil adhered to the surface layer of aluminum material. The invention according to the aforementioned Item 27 provides that degreasing can be performed reliably because the degreasing is performed with an organic solvent . The invention according to the aforementioned Item 28 provides that degreasing can be performed reliably because the degreasing is performed with water containing a surfactant. The invention according to the aforementioned Item 29 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics resulting in a large capacitance by a method wherein intermediate annealing in the oxidative atmosphere, finish cold rolling are preformed and further heated in the oxidative atmosphere, thereafter the surface layer of aluminum material is removed by washing, which can solve aluminum material uniformly upon washing; and then the final annealing is preformed. The invention according to the aforementioned Item 30 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics resulting in a large capacitance by a method wherein the intermediate annealing in the oxidative atmosphere, surface layer removing of aluminum material by washing, finish cold rolling are performed, and further heated in oxidative atmosphere, thereafter the surface layer of aluminum material is removed by washing, which can solve aluminum material uniformly upon washing; and then final annealing is preformed. The invention according to the aforementioned Item 31 provides that the surface layer of aluminum material can be removed reliably by washing because the cleaning liquid for washing is an alkaline aqueous solution. The invention according to the aforementioned Item 32 provides that the surface layer of aluminum material can be removed reliably by washing because the cleaning liquid for washing is an acid aqueous solution. The invention according to the aforementioned Item 33 provides that the surface layer of aluminummaterial can be removed more reliably because the washing is performed sequentially with an alkaline aqueous solution and an acid aqueous solution. The invention according to the aforementioned Item 34 provides that the surface layer can be removed more effectively because an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate. The invention according to the aforementioned Item 35 provides that the surface layer can be removed more effectively because an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, and acids including phosphorous. The invention according to the aforementioned Item 36 provides that the enhancement effect of capacitance can be surely obtained by uniform dissolution of aluminum material because the average removed amount of aluminum material surface layer by washing, after heating in oxidative atmosphere, performing after a finish cold rolling, is not less than lnm, and not more than 500 nm per one side of aluminum material. The invention according to the aforementioned Item 37 provides that while an excess thickening of oxide layer on aluminum material surface layer is suppressed, sufficient oxidization can be performed, then the surface layer of aluminum material can dissolve uniformly upon surface layer removing by washing, because the heating temperature in the oxidative atmosphere after finish cold rolling is 50 to 400 °C. The invention according to the aforementioned Item 38 provides that while useless energy consumption is suppressed, sufficient oxidization on aluminum material surface layer can be performed, then the surface layer of aluminummaterial can dissolve uniformly upon surface layer removing by washing, because the heating time in oxidative atmosphere after finish cold rolling is not less than 3 sec, and not more than 72 hr. The invention according to the aforementioned Item 39 provides aluminum material for electrolytic capacitor electrodes with a stable excellent etching characteristics by a method where the intermediate annealing is performed in the oxidative atmosphere at a temperature of higher than 200° C, and lower than 320° C, which allows a sufficient texture to grow preferentially recrystallized grain with a cubic orientation in final annealing. The invention according to the aforementioned Item 40 provides sufficient oxidization on aluminum material surface layer because the oxygen density of heating atmosphere in the oxidative atmosphere, performing after finish cold rolling, is not less than 0.1 volume% . The invention according to the aforementioned Item 41 provides sufficient oxidization on aluminum material surface layer because the oxygen density of heating atmosphere in oxidative atmosphere in intermediate annealing is not less than 0.1 volume% . The invention according to the aforementioned Item 42 provides aluminum material for electrolytic capacitor electrodes with better performances by a method wherein the degreasing is performed, after cold rolling before intermediate annealing, in a process prior to surface layer removing of aluminum material by last washing, which can remove oils adhered to the surface layer of aluminum material. The invention according to the aforementioned Item 43 provides that degreasing can be performed reliably because the degreasing is performed with an organic solvent . The invention according to the aforementioned Item 44 provides that degreasing can be performed reliably because the degreasing is performed with water containing a surfactant . The invention according to the aforementioned Item 45 provides aluminum material for electrolytic capacitor electrodes with an excellent characteristics resulting in a large capacitance by performing final annealing, after tensile strain application in a course of hot rolling and cold rolling, then intermediate annealing, thereafter before the start of final annealing, wherein after the tensile strain application, aluminum material is heated in oxidative atmosphere before final annealing, thereafter the surface layer of aluminum material is removed by washing, which can solve aluminum material uniformly upon washing; and then the final annealing is performed.. The invention according to the aforementioned Item 46 provides that the surface layer of aluminum material can be removed reliably by washing because the cleaning liquid for washing is an alkaline aqueous solution. The invention according to the aforementioned Item 47 provides that the surface layer of aluminum material can be removed reliably because the cleaning liquid for washing is an acid aqueous solution. The invention according to the aforementioned Item 48 provides that the surface layer can be removed more reliably because the washing is performed sequentially with an alkaline aqueous solution and an acid aqueous solution. The invention according to the aforementioned Item 49 provides that the surface layer can be removed more effectively because an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate. The invention according to the aforementioned Item 50 provides that the surface layer can be removed more effectively because an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, and acids including phosphorous. The invention according to the aforementioned Item 51 provides that the enhancement effect of capacitance can be surely obtained by uniform dissolution of aluminum material because the average removed amount of aluminum material surface layer by washing, after heating in oxidative atmosphere, is not less than lnm, and not more than 500 nm per one side of aluminum material. The invention according to the aforementioned Item 52 provides that while an excess thickening of oxide layer on aluminum material surface layer is suppressed, sufficient oxidization can be performed, then the surface layer can dissolve uniformly upon surface layer removing by washing, because the heating temperature in the oxidative atmosphere is 50 to 400 °C. The invention according to the aforementioned Item 53 provides that while useless energy consumption is suppressed, sufficient oxidization on aluminum material surface layer can be performed, then the surface layer can dissolve uniformly upon surface layer removing by washing, because the heating time in the oxidative atmosphere is not less than 3 sec, and not more than 72 hr . The invention according to the aforementioned Item 54 provides sufficient oxidization on aluminum material surface layer because the oxygen density of heating atmosphere in the oxidative atmosphere is not less than 0.1 volume%. The invention according to the aforementioned Item 55 provides aluminum material for electrolytic capacitor electrodes with an excellent characteristics resulting in a large capacitance by performing tensile strain application and final annealing, in a course of hot rolling and cold rolling, then intermediate annealing, thereafter before the start of final annealing, wherein the intermediate annealing is performed in the oxidative atmosphere, thereafter at least one time of surface layer removing of aluminum material by washing is performed in a process prior to final annealing, which can solve aluminum material uniformly upon washing; and then the final annealing is performed. The invention according to the aforementioned Item 56 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics resulting in a large capacitance by a method wherein the surface layer removing of aluminum material by washing is performed after tensile stain application before final annealing, which can solve aluminum material uniformly upon washing; and then the final annealing is performed. The invention according to the aforementioned Item 57 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristics resulting in a large capacitance by a method wherein the surface layer removing of aluminum material by washing is performed after intermediate annealing before tensile stain giving, which can solve aluminum material uniformly upon washing; and then the final annealing is performed. The invention according to the aforementioned Item 58 provides aluminum material for electrolytic capacitor electrodes with an excellent characteristics by a method wherein after the tensile strain application prior to final annealing, the surface layer removing of aluminum material by washing is performed after heating aluminum material in oxidative atmosphere, which gives aluminum material the uniform solubility of surface layer upon washing, by intermediate annealing in the oxidative atmosphere and heating in the oxidative atmosphere. The invention according to the aforementioned Item 59 provides that the surface layer of aluminum material can be removed reliably by washing because the cleaning liquid for washing is an alkaline aqueous solution. The invention according to the aforementioned Item 60 provides that the surface layer of aluminum material can be removed reliably because the cleaning liquid for washing is an acid aqueous solution. The invention according to the aforementioned Item 61 provides that the surface layer of aluminum material can be removed more reliably because the washing is performed sequentially with an alkaline aqueous solution and an acid aqueous solution. The invention according to the aforementioned Item 62 provides that the surface layer can be removed more effectively because an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate. The invention according to the aforementioned Item 63 provides that the surface layer can be removed more effectively because an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, and acids including phosphorous. The invention according to the aforementioned Item 64 provides that the enhancement effect of capacitance can be surely obtained by uniform dissolution of aluminum material because the average removed amount of aluminum material surface layer by washing, after heating in the oxidative atmosphere, is not less than lnm, and not more than 500 nm per one side of aluminum material. The invention according to the aforementioned Item 65 provides that while the excess thickening of oxide layer on aluminum material surface layer is. suppressed, sufficient oxidization can be performed, which can solve the surface layer uniformly upon surface layer removing by washing afterwards, because the heating temperature in the oxidative atmosphere, performing after tensile strain application, is 50 to 400 °C. The invention according to the aforementioned Item 66 provides that while useless energy consumption is suppressed, sufficient oxidization on aluminum material sur ace layer can be performed, which can solve the surface layer of aluminum material uniformly upon surface layer removing by washing afterward, because the heating time in the oxidative atmosphere, performing after tensile strain application, is not less than 3. sec, and not more than 72 hr. The invention according to the aforementioned Item 67 provides that solubility of aluminum material surface layer becomes uniform because the intermediate annealing is performed in the oxidative atmosphere at a temperature of higher than 200° C, and lower than 300° C. The invention according to the aforementioned Item 68 provides sufficient oxidization on aluminum material surface layer because the oxygen density of heating atmosphere in the oxidative atmosphere, performing after tensile strain application, is not less than 0.1 volume%. The invention according to the aforementioned Item 69 provides sufficient oxidization on aluminum material surface layer because the oxygen density of heating atmosphere in the oxidative atmosphere, performing in intermediate annealing, is not less than 0.1 volume% . The invention according to the aforementioned Item 70 provides that the thickening of oxide layer on aluminum material surface layer can be suppressed, and the effect of surface layer removing is exerted effectively by heating aluminum material in the oxidative atmosphere and washing because the final annealing is performed in an inert gas atmosphere. The invention according to the aforementioned Item 71 provides that aluminum material surface layer generating uniform etch-pits can be obtained because the final annealing is performed at a temperature of higher than 450° C, and lower than 600° C. The invention according to the aforementioned Item 72 provides that the deterioration of etching characteristic resulting from too much impurity can be prevented because the aluminum purity of aluminummaterial is not less than 99.9 weight% . The invention according to the aforementioned Item 73 provides aluminum material for electrolytic capacitor electrodes with an excellent etching characteristic. The invention according to the aforementioned Item 74 provides anode material for a middle or high voltage with an excellent etching characteristic. The invention according to the aforementioned Item 75 provides manufacturing of electrode material for electrolytic capacitors with a large capacitance by etching. The invention according to the aforementioned Item 76 provides manufacturing of electrode material for suitable electrolytic capacitors as anode material because the formation of dielectric by anodizing is performed after etching. The invention according to the a orementioned Item 77 provides that a large number of deep and thick tunnel structure pits can be generated by at least a part of the etching being performed by a direct current electrolytic etching, and the effect is exerted efficiently by the heating in the oxidative atmosphere and surface layer removing by washing. The invention according to the aforementioned Item 78 provides anode material for aluminum electrolytic capacitors with a large capacitance. The invention according to the aforementioned Item 79 provides aluminum electrolytic capacitors with a large capacitance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The inventor of this application has found that heating of aluminum material in the oxidative atmosphere prior to removal of the surface layer of aluminum material by washing could uniformly dissolve the surface layer of aluminum material during washing, and generate uniform etch pits when electrolytic etching is provided to the aluminum material to be subsequently obtained after final annealing, thus significantly improving etching characteristic . The inventor has also found that in a method of manufacturing aluminum material for electrolytic capacitors through sequential implementation of cold rolling, intermediate annealing, finish cold rolling, and final annealing on aluminum material, when intermediate annealing is carried out in the oxidative atmosphere and the surface layer of aluminum material is removed by washing in a process following the intermediate annealing and preceding final annealing, solubility of the surface layer of aluminum material becomes uniform due to oxidation of the aluminum material by intermediate annealing in the oxidative atmosphere, and thus etching characteristic of the aluminum material after final annealing significantly improves. The inventor of this application has also found that when a surface layer of aluminum material is dissolved by washing and subject to final annealing, after aluminum material is subject to intermediate annealing in oxidative atmosphere following cold rolling and is heated in oxidative atmosphere following finish cold rolling, because of oxidation of the aluminum material caused by intermediate annealing in the oxidative atmosphere and heating in oxidative atmosphere after finish cold rolling, solubility of the surface layer of aluminum material becomes uniform, and thus etching characteristic of the aluminum material after final annealing significantly improves . The inventor has also found that when a surface layer of aluminum material is dissolved by washing and subjected to final annealing after it is.given tensile strain following intermediate annealing and further heated in oxidative atmosphere, because of oxidation of the aluminum material by heating in the oxidative atmosphere after provision of tensile strain completes, solubility of the surface layer of aluminum material becomes uniform and thus etching characteristic of the aluminum material after final annealing significantly improves. In addition, the inventor has found that in manufacture of aluminummaterial for electrolytic capacitors wherein hot and cold rolling are conducted followed by intermediate annealing, tensile strain is given in the period after intermediate annealing and before start of final annealing, and then final annealing is conducted, wherein if said intermediate annealing is conducted in the oxidative atmosphere and a surface layer of aluminum material is removed by washing in a process following intermediate annealing and preceding final annealing, because of oxidation of the aluminum material by intermediate annealing in the oxidative atmosphere, solubility of the surface layer of aluminum material in washing to be subsequently done becomes uniform, and thus etching characteristic of the aluminum material after final annealing significantly improves. In addition, sequential implementation of heating in the oxidative atmosphere, removal of a surface layer of aluminum material by washing, and final annealing after intermediate annealing in the oxidative atmosphere and addition of tensile strain can effect better etching characteristic because of heating in the oxidative atmosphere following addition of tensile strain, in addition to intermediate annealing in the oxidative atmosphere. As described above, addition of tensile strain is the process to be conducted in place of finish cold rolling so that cubic texture of aluminum can be developed in final annealing. However, as appropriate tensile strain has a lower processing rate than that of finish cold rolling (refer to Patent Document 1 and Patent Document 2) , it can provide more uniform solubility of a surface layer of aluminum material and better improvement of etching characteristic, compared with the case in which the surface layer of aluminum material is removed by washing after finish cold rolling. In the following, we describe a method of manufacturing aluminum material for electrolytic capacitors in detail.

[Purity of Aluminum Material] Purity of aluminum material is not specifically limited if it falls within the grade for electrolytic capacitors. However, preferably, the purity would be not less than 99.9 mass %, and specifically, not less than 99.95 mass % more preferably. In this invention, purity of aluminum material shall be a value of 100 mass % minus total concentration of Fe, Si and Cu (mass %). Pb segregates on a surface layer of aluminum material during final annealing and has a considerable effect on generation of etch pits. When a tunnel-like etch pit is generated by direct current (DC) etching method, in some etching method, etch pit dispersibility is poor if there is too little Pb, while large amount of surface dissolution of aluminum material is caused by etching if there is too much Pb. Thus, the aluminum material may contain moderate amounts of Pb, as necessary. We can recommend that adjustment be made, for instance, so that aluminum material contains Pb of 0.00002 to 0.0002 mass %.

[Manufacturing process according on a First Embodiment (Till end of final annealing)] In this embodiment, manufacture of aluminum material, although it is not defined, takes place in the order of adjustment of soluble components/slab casting, hot rolling, cold rolling, intermediate annealing, cold rolling including finish cold rolling (rolling of low rolling reduction), and final annealing. Prior to final annealing, after being heated in oxidative atmosphere, the surface layer of aluminum material is removed by washing. It would be preferable to conduct heating in the oxidative atmosphere following cold rolling and to remove a surface layer of aluminum material by washing. In addition, in order to increase fraction of cube orientation after final annealing, intermediate annealing should be conducted, as necessary. The heating in the oxidative atmosphere and removal of surface layer of aluminum material by washing may be carried out once, respectively, or heating and removal by washing may be alternately carried out several times . The heating in the oxidative atmosphere is conducted by atmosphere heating rather than contact with a heating body. In atmosphere heating, as aluminum material does not come in contact with the heating body, unlike heating by coming in contact with a heating body, heating leaves no wrinkle or mark. Hence, this invention has adopted atmosphere heating. As a method of heating in the oxidative atmosphere, ventilation heating, radiation heating, etc. can be exemplified. In addition, shape of aluminum material to be heated is not specifically defined. The aluminum material wound around the coil may be batch heated_.or it may be wound around the coil, after the coil is rewound and it is continuously heated. Preferably, heating temperature of the aluminum material in the oxidative atmosphere would be 50 to 400° C. When the heating temperature is less than 50° C, oxidation of the surface layer of aluminum material may not be adequate and the aluminum material may not dissolve uniformly when the surface layer thereof is removed. When the heating temperature exceeds 400° C, oxide film of the surface layer of aluminum material will be thick, which deteriorates solubility of the aluminum material and makes it difficult to dissolve the aluminum material in uniform manner. Particularly preferable heating temperature would be 70 to 350° C, and 70 to 240° C, in particular. Preferably, the heating time would be not less than 3 seconds and not more than 72 hr. If heating time is less than 3 seconds, the surface layer of aluminum material may not be oxidized adequately and the aluminum material may not dissolve uniformly when the surface layer thereof is removed. When the heating time exceeds 72 hr, dissolving uniformity during removal of the surface layer of aluminum material becomes almost flat , and thus cost will be higher due to energy consumption during heating. Preferable heating time, in particular, would be not less than 10 seconds and not more than 48 hr, and particularly, not less than 70 seconds and not more than 48 hr. For the heating temperature and time in the oxidative atmosphere, appropriate conditions should be selected, depending on a heating method. For example, when aluminum material is heated in the condition being wound up as a coil, it would be preferably heated at 50 to 240° C for 30 min to 72 hr, and more preferably at 70 to 240° C for 1 to 48 hr. In addition, when aluminum material unwound from a coil or sheet-cut aluminum material is heated, the

heating time t (hour) would be preferably 10/(1.44 X x¹"⁵) ≤- t ≤≥

72, where x is the heating temperature (°C). It would be more

preferably 10/(1.44 X x^1,5) ≤ t ≤ 48.

Preferably, oxygen concentration in the oxidative atmosphere during heating of aluminum material in the oxidative atmosphere would be not less than 0.1 volume %. If the oxygen concentration is less than 0.1 volume %, the surface of aluminum material may not be adequately oxidized when it is heated. Preferably, the oxygen concentration would be not less than 1 volume %, in particular. More preferably, it would be not less than 5 volume %, in particular, and air can be preferably used as the oxidative atmosphere. Although cleaning liquid to be used in removing a surface layer of aluminum material by washing is not specifically defined, alkaline solution or acid solution may be used. The surface layer may be removed by using either alkaline solution or acid solution, or it may be washed with acid solution after being removed with alkaline solution. As alkali, sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate may be exemplified, and one or more alkali selected from the above alkalis may be used as cleaning liquid by being dissolved in water. As acid, one or more acid selected from those including hydrochloric acid, sulfuric acid, nitric acid, and acids including phosphorus element shall be used. As acids including phosphorus element, orthophosphoric acid (hereafter referred to as phosphoric acid) , pyrophosphoric acid, metaphosphoric acid, and polyphosphoric acid may be exemplified. In addition, as acid to be used in removing the surface layer of aluminum material, perchloric acid and hypochlorous acid may be used. The removal amount of the surface layer of aluminum material may be adjusted by keeping at an appropriate level concentration of alkalis or acids, temperature of alkaline or acid aqueous solution, and contact time of the aluminum material with alkaline or acid aqueous solution. In addition, in order to enhance cleaning effect of the surface layer of aluminum material, a surfactant or a chelating agent may be added to the cleaning liquid. The removal amount of the surface layer of aluminum material by washing is a mean value, and would be preferably not less than 1 mm and not more than 500nm per side of the aluminum material. If the removal amount of the surface layer is less than 1 mm, removal of the oxide film on the surface layer of aluminum material may be inadequate. If the surface layer is removed by 500 nm or more, etch pit nucleation on the surface layer of aluminum material will be suppressed, thus even degrading etching characteristic and reducing capacitance. Preferably, the removal amount of the surface layer by washing would be not less than 1.5 nm and not more than 200 nm, more preferably, not less than 5 nm and not more than 200 nm, and most preferably, not less than 10 nm and not more than 150 nm. Although density of the oxide film on the surface layer of aluminum material differs from that of aluminum, which is metal, the removal amount of surface layer of aluminum material, D (nm) ,

in this application shall be defined as D(nm) = E X 10⁷/2.7, using

E (g/cm²), decrease in mass per unit surface area by washing and density of aluminum, 2.7g/cm³. Although a method of bringing cleaning liquid with aluminum material is not specifically defined, immersion, contact of aluminum material with surface of cleaning liquid, spraying, etc, may be possible. Any process or process condition other than those defined in this invention shall not be specifically defined, and common procedure may be just followed. In addition, a method of manufacturing aluminum material may be changed, as appropriate, depending on a relationship with etching conditions of the aluminum material. Further, degreasing may also be carried out after cold rolling and before removal of a surface layer of aluminum material by washing. Although a method of degreasing is not specifically defined, degreasing may be possible by bringing the aluminum material into contact with a solution prepared by adding a surfactant to water, or organic solvent. Although a method of bringing aluminum material into contact with a solution prepared by adding a surfactant to water, or organic solvent is not specifically defined, immersion, contact of aluminum material onto surface of cleaning liquid, spraying, etc. may be possible. Unless otherwise defined, the organic solvent may be, for instance, alcohol, diol, aromatic hydrocarbons such as toluene and xylene, etc. , alkane series of hydrocarbons , cyclohexane, ketone, ether, ester, petrochemical products, etc. Examples of alcohol mentioned above include methanol (CH₃OH) , ethanol (C₂H₅OH) , 1-propanol (CH₃CH₂CH₂OH) , 2-propanol (CH₃CH₂CH₂ (OH)CH₃), 1-butanol (CH3CH₂CH₂CH₂OH) , 2-butanol(CH₃CH₂CH₂(OH)CH₃) , 1-pentanol (CH3CH2CH2CH2CH2OH) , 2-pentanol (CH₃CH₂CH₂CH₂(OH)CH3) , etc. , and those that can be expressed by C_nH_2π+ι (n=a natural number of 1 to 10) are preferable. In addition, alicyclic hydrocarbons such as cyclohexanol, etc. can also be used. As examples of diol mentioned above, 1,2-ethanediol (HOCH₂ CH₂OH), 1,2-propanediol (CH₃CH(OH) CH₂OH) , 1 , 3-propanediol (HOCH₂ CH₂ CH₂OH), etc., may be exemplified. Examples of alkane series of hydrocarbons mentioned above include pentane (C₅H₁2), hexane (C₆Hι₄), heptane (C₇H₁₆), octane (C₈Hι₈), nonane (C₉H₂o)# decane (C10H22 etc., and what is expressed by C_nH_2n-.2) (n=a natural number of 5 to 15) is preferable. In addition, any alicyclic hydrocarbon such as cyclohexane, etc. may be applicable. As examples of ketone mentioned above, acetone (CH₃COCH₃), 2-butanone (CH₃COC₂H₅), 3-pentanone (CH3CH2COCH₂CH₃) , 3-methyl-2-butanone (CH3COCH(CH₃)₂) , etc. may be exemplified, and those that can be expressed by R1COR2 (RI and R2 : being an aliphatic hydrocarbon group, and a total carbon number, of RI and R2 is not more than 8) are preferable. In addition, any cyclic ketone such as cyclohexanone (C₆Hι₀O), etc., may be used. Examples of ether mentioned above include any substance expressed by R1-0-R2 (RI and R2: being an aliphatic hydrocarbon group, and a total carbon number of RI and R2 is not more than 8), and glycolether such as 2-methoxyethanol (CH₃OCH₂CH₂OH) , 2-ethoxyethanol (CH3CH₂OCH₂CH₂OH) , 2-butoxyethanol (CH₃CH₂CH₂CH₂OCH₂CH₂OH) , 2- (2-ethoxy) -ethoxyethanol )[CH3CH₂θCH₂CH₂OCH₂CH₂OH), etc. As examples of ester mentioned above, acetic ester expressed by CH3COOR (R: an aliphatic hydrocarbon group with a carbon number being 1 to 5) may be exemplified. Examples of petrochemical products mentioned above include industrial-gasoline (JIS K 2201), motor gasoline (JIS K 2202), aviation gasoline (JIS K 2206), lamp oil (JIS K 2203), light oil (JIS K 2204) , petroleum ether (JIS K 8593) , petroleum benzine (JIS K 8594), ligroin (JIS K 8937), kerosene, etc. Unless otherwise defined, as a surfactant contained in a solution to be used for degreasing that is prepared by adding the surfactant to water, anionic surfactant, cationic surfactant, and nonionic surfactant may be used. As anionic surfactant, sulfate ester salt and sulfonate may be used. As sulfate ester salt mentioned above, R-OS0₃Na (R=a saturated hydrocarbon group having carbon number of 8 to 18 or unsaturated hydrocarbon group having one double bond) may be used, and specifically, sodium dodecyl sulfate (Cι₂H₂5θS0₃Na) , sodium hexadecyl sulfate (Ci₆H₃3θS0₃Na) , sodium stearyl sulfate (Cι₈H₃₇OS0₃Na) , sodium oleyl sulfate (C₁₈H35θS0₃Na) , etc. may be exemplified. As sulfonate mentioned above, those expressed by R-S0₃Na (R= a saturated hydrocarbon group having carbon number of 8 to 18 or unsaturated hydrocarbon group having one double bond) or R-S0₃Na (R: a saturated hydrocarbon group with alkyl group having carbon number 8 to 14, or unsaturated hydrocarbon group having one double bond) such as sodium dodecylbenzene sulfonate (Cι₂H₂₅-CyH₄-S0₃Na) , etc. may be used. As cationic surfactant, quaternary ammonium salt expressed

by R-N(CH₃)₃ ^• CI (R= an unsaturated hydrocarbon group with a carbon

number of 8 to 16) may be used. As nonionic surfactant, nonionic surfactant of polyethyleneglycol type expressed by R-0-(-CH₂CH₂0)nH (R= a saturated hydrocarbon group with a, carbon number of 8 to 16 or unsaturated hydrocarbon group having one double bond, n=6 to 14) or R-0-(-CH₂CH₂0)nH (R=a saturated hydrocarbon group with alkyl group having a carbon number of 8 to 12, or alkyl phenyl radical that is an unsaturated hydrocarbon group having one double bond, n=6 to 14) may be exemplified. In addition, any surfactant with n exceeding the above limits may be contained in nonionic surfactant, with molar ratio of 50% or less. At least one kind of the above surfactants may be added to water and used as a cleaning liquid. Any surfactant with a carbon number of the surfactant below the above range may be used with the molar ratio of 50% or less . Since mixing of anion surfactant and cationic surfactant in water generates precipitates, it would be preferable to avoid the mixing. Unless otherwise defined, preferably, adding concentration of the surfactants would be above critical micelle concentration so as to fulfill the degreasing effect. Unless otherwise defined, for processing atmosphere in final annealing of aluminum material, in order to avoid increasing thickness of oxide coating, heating in an atmosphere with less water and oxygen is preferable. To be specific, heating in inert gases such as argon, nitrogen, etc. or in vacuum of O.lPa or less is preferable. In addition, hydrogen gas could be preferably used as an atmosphere for final annealing. Preferably, area fraction of cube orientation of aluminum material after final annealing is not less than 90%. Although a final annealing method is not specifically defined, it may be batch annealing with aluminum material wound around a coil or the material may be wound around the coil, after the coil is rewound and it is continuously annealed. At least either of batch annealing or continuous annealing may be carried out once or more. Although the annealing temperature and annealing time are not specifically defined, if batch annealing is to be done on coiled material, it would be preferably annealed at 450 to 600° C for a time of 10 min to 50 hr. This is because it might not be possible to obtain a surface on which etch pit could be generated uniformly, if the temperature is less than 450° C and the time is less than 10 min. On the contrary, if annealing takes place above 600° C, aluminum material tends to stick together in the case of batch annealing on coiled material. In addition, even though it is annealed more than 50 hr, the surface expansion effect by etching becomes saturated, even leading to increased thermal energy cost. Preferably, the annealing temperature is 450 to 590° C, in particular, and more preferably 460 to 580° C. Preferably, the annealing time is 20 min to 40 hr. In addition, temperature rising rate/pattern is not specifically defined. Temperature rising at a certain rate is also applicable, or step-by-step temperature rising/cooling is applicable by repeating cycles of temperature rising and temperature maintenance. In the annealing process, annealing in the temperature zone from 450 to 600° C for a total of 10 min to 50 hr will be applicable.

[Manufacturing process according on a Second Embodiment (till end of final annealing) ]

In this embodiment, manufacture of aluminum material, although it is not defined, takes place in the order of adjustment of soluble components/slab casting, hot rolling, cold rolling, intermediate annealing in the oxidative atmosphere, finish cold rolling (rolling with low reduction in thickness), and final annealing, and removal of a surface layer of aluminum material by washing takes place in a process after intermediate annealing in the oxidative atmosphere and before final annealing. The intermediate annealing in the oxidative atmosphere is conducted by atmosphere heating, rather than by contact with a heating body. In atmosphere heating, as aluminum material does not come in contact with the heating body, unlike heating by coming in contact with a heating body, heating leaves no wrinkle or mark. Hence, this invention has adopted intermediate annealing by atmosphere heating. As a method of heating during intermediate annealing in the oxidative atmosphere, ventilation heating, radiation heating, etc. can be exemplified. In addition, although temperature rising speed/pattern is not specifically defined, it should be conducted under the conditions that increase area fraction of cube orientation after final annealing. In addition, the form of aluminum material to be heated is not specifically defined. The aluminum material may be batch annealed with it wound around a coil or the material may be wound around the coil, after the coil is rewound and it is continuously annealed. Preferably, the oxygen concentration in the oxidative atmosphere during intermediate annealing would be not less than 0.1 volume % . If the oxygen concentration is less than 0.1 volume % , the aluminum material surface may not be oxidized adequately when it is heated. Preferably, the oxygen concentration would be not less than 1 volume %, more preferably not less than 5 volume %, in particular, and air could be preferably utilized as the oxidative atmosphere. If air is used as oxidative atmosphere, there is no need to control the oxygen concentration, thereby being able to plan cost reduction of the intermediate annealing process. Preferably, the intermediate annealing temperature in the oxidative atmosphere would be not less than 200° C and not more than 320° C. Intermediate annealing falling within the temperature range could oxidize the aluminum material and achieve uniform solubility of the surface layer thereof. If the intermediate annealing temperature is less than 200° C, a sufficient texture that allows recrystallized grain with the cube orientation during final annealing to grow preferentially cannot be obtained. If it exceeds 320° C, recrystallized grains that will block preferential growth of the cube orientation grain during final annealing will grow. The intermediate annealing temperature and duration that allow acquisition of the favorable area fraction of cube orientation depend on composition of the aluminum material, and the condition that allows acquisition of a high area fraction of cube orientation after final annealing should be selected. Finish cold rolling is a process that is conducted to control cube orientation in combination with intermediate annealing, for which a publicly known method may be used. Preferably, the rolling reduction in finish cold rolling would be not less than 10% and not more than 25%. If the rolling reduction is less than 10%, strain by working for preferentially growing crystal grains with cube orientation is not adequate. If the rolling reduction exceeds 25%, in final annealing non-cube orientation grains grow due to introduced strain by working, which will inhibit preferential growth of crystal grains with cube orientation. In a process following intermediate annealing and preceding final annealing, removal of the surface layer of aluminum material is carried out . Although the cleaning liquid is not specifically defined, alkaline aqueous solution or acid aqueous solution may be used. Removal of the surface layer may be done with either alkaline aqueous solution or acid aqueous solution, or the surface layer may be removed with alkaline solution and then washed with acid aqueous solution. As alkali, sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate may be exemplified, and one or more alkali selected from the above alkalis may be used as cleaning liquid by being dissolved in water. As acid, one or more acid selected from hydrochloric acid, sulfuric acid, nitric acid, and acids including phosphorus element shall be used. As acids including phosphorus element, orthophosphoriσ acid (hereafter referred to as phosphoric acid) , pyrophoric acid, metaphosphoric acid, and polyphosphoric acid may be exemplified. In addition, as acid to be used in removing the surface layer of aluminum material, perchloric acid and hypochlorous acid may be used. The removal amount of the surface layer of aluminum material may be adjusted by keeping at an appropriate level concentration of alkalis or acids, temperature of alkaline or acid aqueous solution, and contact time of the aluminum material with alkaline or acid aqueous solution. In addition, in order to enhance cleaning effect of the surface layer of aluminummaterial, a surfactant or chelating agent may be added to the cleaning liquid. The removal amount of the surface layer of aluminum material by washing is a mean value, and shall be preferably not less than 1 mm and not more than 500nm per side of the aluminum material. If the removal amount of the surface layer is less than 1 mm, removal of the oxide film on the surface layer of aluminum material may not be adequate. If the surface layer is removed by 500 nm or more, etch pit nucleation on the surface layer of aluminum material will be suppressed, thus even degrading etching characteristic and reducing capacitance. When washing is done after cold rolling ends, preferably, the removal amount of the surface layer by washing would be not less than 1.5 nm and not more than 200 nm. Although density of the oxide film on the surface layer of aluminum material differs from that of aluminum, which is metal, the removal amount of surface layer of aluminum material, D (nm) , in this application, it shall be defined as D(nm) = E X 10⁷/2.7,

using E (g/cm²) , decrease in mass per unit surface area by washing and density of aluminum, 2.7g/σm³. Washing should be carried out by bringing the aluminum material into contact with the cleaning liquid. Although a method of contact is not specifically defined, immersion, contact of the aluminum material with surface of the cleaning liquid, spraying, etc, may be possible. The removal of the surface layer of aluminum material by washing may take place following finish cold rolling and preceding final annealing, or following intermediate annealing and preceding finish cold rolling. In addition, in a process after hot rolling and before intermediate annealing, the surface layer of aluminum material may be removed by washing with said cleaning liquid. Although the cleaning liquid to be used in cleaning in a process after hot rolling and before intermediate annealing may be selected in accordance with the intended use, and shall not be specifically defined, the same cleaning liquid as that to be used in washing after the intermediate annealing may be used. Degreasing may take place in a process after cold rolling prior to intermediate annealing and before final annealing. The same method of degreasing as that described in the manufacturing process on the first embodiment may be used, description of which is thus omitted here. The process atmosphere during final annealing of aluminum material, area fraction of cube orientation of the aluminum material after final annealing, a method of final annealing, and temperature, time, temperature rising rate/pattern during annealing are same as those described in the manufacturing process on the first embodiment.

[Manufacturing process according on a Third Embodiment (till end of final annealing)] In this embodiment, manufacture of aluminum material, although it is not defined, takes place in the order of adjustment of soluble components/slab casting, hot rolling, cold rolling, intermediate annealing in the oxidative atmosphere, finish cold rolling (rolling with reduction in thickness), heating in the oxidative atmosphere, removal of a surface layer of aluminum material by washing, and final annealing. Heating in the oxidative atmosphere to be conducted after finish cold rolling and before final annealing, and subsequent removal of the surface layer of aluminum material by washing may be carried out once, respectively, or heating in the oxidative atmosphere and subsequent removal of the surface layer of aluminum material by washing may be alternately carried out several times . The intermediate annealing in the oxidative atmosphere is conducted by atmosphere heating rather than contact with a heating body. In atmosphere heating, as aluminum material does not come in contact with the heating body, unlike heating by coming in contact with a heating body, heating leaves no wrinkle or mark. Hence, this invention implements intermediate annealing with atmosphere heating. As a method of heating during intermediate annealing in oxidative atmosphere, ventilation heating, radiation heating, etc, can be exemplified. In addition, although temperature rising speed/pattern in heating the aluminum material in the oxidative atmosphere is not specifically defined, heating should be conducted under the conditions that increase area fraction of cube orientation after final annealing. In addition, the form of aluminum material to be heated is not specifically defined. The aluminum material may be batch annealed with it wound around a coil, or the material may be wound around the coil, after the coil is rewound and it is continuously annealed. Preferably, the intermediate annealing temperature in the oxidative atmosphere would be not less than 200° C and not more than 320° C. If the intermediate annealing temperature is less than 200° C, sufficient texture that allows recrystallized grain having the cube orientation during final annealing to grow preferentially cannot be obtained. If it exceeds 320° C, recrystallized grains that will block preferential growth of the cube orientation grain during final annealing will grow. The intermediate annealing temperature and duration that allow acquisition of the favorable area fraction of cube orientation depend on composition of the aluminum material, and the condition that allows acquisition of a high area fraction of cube orientation after final annealing should be selected. Intermediate annealing falling within the said temperature range could oxidize the aluminum material and achieve uniform solubility of the surface layer thereof. Finish cold rolling is a process that is conducted to control a cube orientation in combination with intermediate annealing, for which a publicly known method may be used. Preferably, the rolling reduction in finish cold rolling would be not less than 10% and not more than 25%. If the rolling reduction is less than 10%, strain by working for preferentially growing crystal grains having cube orientation is not adequate. If the rolling reduction exceeds 25%, in final annealing non-cube orientation grains grow due to introduced strain by working, which will inhibit preferential growth of crystal grains with cube orientation. Heating in oxidative atmosphere in a process following finish cold rolling is conducted by atmosphere heating rather than contact with a heating body. In atmosphere heating, as aluminum material does not come in contact with the heating body, unlike heating by coming in contact with a heating body, heating leaves no wrinkle or mark. Hence, this invention has adopted atmosphere heating. As a method of heating in the oxidative atmosphere to be conducted in a process following finish cold rolling, ventilation heating, radiation heating, etc. can be exemplified. Heat of the aluminum material following cold rolling may be used for heating in the oxidative atmosphere. Temperature rising rate/pattern in heating the aluminum material in the oxidative atmosphere is not specifically defined, and temperature rising at a certain temperature is also applicable, or step-by-step temperature rising/cooling is applicable by repeating cycles of temperature rising and temperature maintenance. In addition, the form of aluminum material to be heated is not specifically defined. The aluminum material may be batch annealed with it wound around a coil or the material may be wound around the coil, after the coil is rewound and it is continuously annealed. Preferably, the heating temperature of the aluminummaterial in the oxidative atmosphere to be conducted in a process following finish cold rolling would be 50 to 400° C. If the heating temperature is less than 50° C, the surface layer of aluminum material may not be oxidized adequately and the aluminummaterial may not dissolve uniformly when the surface layer thereof is removed. When the heating temperature exceeds 400° C, the oxide film on the surface layer of aluminum material thickens , thereby deteriorating solubility of the aluminum material and making it difficult to dissolve the aluminum material uniformly. Preferably, the heating temperature of the aluminum material would be 70 to 350° C, and 70 to 240° C, in particular. Preferably, the heating time in the oxidative atmosphere to be conducted in a process after finish cold rolling would be not less than 3 seconds and not more than 72 hr. If heating time is less than 3 seconds, the surface layer of aluminum material may not be oxidized adequately and the aluminum material may not melt uniformly when the surface layer thereof is removed. When the heating time exceeds 72 hr, dissolving uniformity during removal of the surface layer of aluminum material becomes almost flat , and thus cost will be higher due to energy consumption during heating. Preferable heating time, in particular, is not less than 10 seconds and not more than 48 hr, and particularly, not less than 70 seconds and not more than 48 hr. Preferably, the oxygen concentration in the oxidative atmosphere during intermediate annealing in the oxidative atmosphere and during heating of the aluminum material in the oxidative atmosphere to be conducted in a process following finish cold rolling would be not less than 0.1 volume %. If the oxygen concentration is less than 0.1 volume %, the surface of aluminum material may not be adequately oxidized when it is heated. Preferably, the oxygen concentration would be not less than 1 volume %, in particular. More preferably, it would be not less than 5 volume %, in particular, and air can be preferably used as the oxidative atmosphere. Although a cleaning liquid to be used for removal of the surface layer of aluminum material by washing is not specifically defined, alkaline solution or acid aqueous solution may be used. Removal of the surface layer may be done with either alkaline solution or acid aqueous solution, or the surface layer may be removed with alkaline solution and then washed with acid aqueous solution. As alkali, sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate may be exemplified, and one or more alkali selected from the above alkalis may be used as cleaning liquid by being dissolved in water. As acid, one or more acid selected from those including hydrochloric acid, sulfuric acid, nitric acid, and acids including phosphorus element shall be used. As acids including phosphorus element, orthophosphoric acid (hereafter referred to as phosphoric acid) , pyrophoric acid, metaphosphoric acid, and polyphosphoric acid may be exemplified. In addition, as acid to be used in removing the surface layer of aluminum material, perchloric acid and hypochlorous acid may be used. The removal amount of the surface layer of aluminum material may be adjusted by keeping at an appropriate level concentration of alkalis or acids, temperature of alkaline or acid aqueous solution, and contact time of the aluminum material with alkaline or acid aqueous solution. In addition, in order to enhance cleaning effect of the surface layer of aluminum material, a surfactant,or chelating agent may be added to the cleaning liquid. Preferably, the amount of aluminum surface to be removed by washing after heating in the oxidative atmosphere to be conducted in a process following finish cold rolling is a mean value, and would be preferably not less than 1 mm and not more than 500nm per side of the aluminum material. If the removal amount of the surface layer is less than 1 mm, removal of the oxide film on the surface layer of aluminum material may be inadequate . If the surface layer is removed by 500 nm or more, etch pit nucleation on the surface layer of aluminum material will be suppressed, thus even degrading etching characteristic and reducing capacitance. Preferably, the removal amount of the surface layer would be not less than 1.5 nm and not more than 200 nm. Although density of the oxide film on the surface layer of aluminum material differs from that of aluminum, which is metal, the removal amount of surface layer of aluminum material, D (nm) ,

in this application shall be defined as D(nm) = E X 10⁷/2.7, using

E (g/cm²), decrease in mass per unit surface area by washing and density of aluminum, 2.7g/cm³. Although a method of bringing cleaning liquid with aluminum material is not specifically defined, immersion, contact of aluminum material with surface of cleaning liquid, spraying, etc, may be possible. In addition to washing after heating in the oxidative atmosphere to be conducted in a process following finish cold rolling, removal of the surface layer of aluminum material by washing may be done in a process after intermediate annealing and before finish cold rolling. The conditions of washing may be implemented to the extent of the conditions of washing after said heating in the oxidative atmosphere. In addition, in a process following hot rolling and preceding intermediate annealing, the surface layer of aluminum material may be removed by washing with the said cleaning liquid. Although the cleaning liquid to be used in a process after hot rolling and before intermediate annealing may be selected in accordance with the intended use, and shall not be specifically defined, it may be same as the cleaning liquid to be used in washing after said heating in the oxidative atmosphere. Degreasing may take place in a process after last cold rolling prior to intermediate annealing and before removal of the surface layer of aluminum material by washing to be carried out at last. The same method of degreasing as that described in the manufacturing process on the said first embodiment may be used, description of which is thus omitted here. The process atmosphere during final annealing of aluminum material, area fraction of cube orientation of the aluminum material after final annealing, a method of final annealing, and temperature, time, temperature rising rate/pattern during annealing are same as those described in the manufacturing process on the first embodiment .

[Manufacturing process according on a Fourth Embodiment (till end of final annealing) ] In this embodiment, manufacture of aluminum material, although it is not defined, takes place in the order of adjustment of soluble components/slab casting, hot rolling, cold rolling, intermediate annealing, addition of tensile strain, heating in the oxidative atmosphere, removal of a surface layer of aluminum material by washing, and final annealing. Heating in the oxidative atmosphere to be conducted after application of tensile strain and before final annealing, and subsequent removal of the surface layer of aluminum material by washing may be implemented once, respectively, or heating in the oxidative atmosphere and subsequent removal of the surface layer of aluminum material by washing may be alternately carried out several times . Application of tensile strain is the process that is conducted to control a cube orientation in combination with intermediate annealing. Unlike finish cold rolling, since application of tensile strain is free from the problem that much lubricant attaches to the surface of aluminummaterial , the surface of aluminum material is easy to oxidize by subsequent heating in the oxidative atmosphere. Addition of tensile strain also has the feature that during final annealing, coarsening of aluminum crystal grains is less likely to occur even though it has thicker foil than that of finish cold rolling, thus making it easier to manufacture thick aluminum material . Although a method of tensile strain application is not specifically defined, a method described in WO 2004/003248 Al may be applied. Preferably, tensile strain to be applied after intermediate annealing would be not less than 1% and not more than 15%. When the tensile strain is less than 1%, strain by working for preferentially growing crystal grains with a cube orientation is inadequate. When it exceeds 15%, the aluminum material may break while being drawn. To apply tensile strain, one-axis tension wherein tension strain is given to only one direction relative to the aluminum material, namely, longitudinally, or two-axis tension wherein tensile strain is given to 2 directions, namely, in lengthwise direction and width direction may be applied. Heating in the oxidative atmosphere in a process following addition of tensile strain is conducted by atmosphere heating rather than contact with a heating body. In atmosphere heating, as aluminum material does not come in contact with the heating body, unlike heating by coming in contact with a heating body, heating leaves no wrinkle or mark. Hence, this invention has adopted atmosphere heating. As a method of heating in the oxidative atmosphere, ventilation heating, radiation heating, etc. can be exemplified. In addition, shape of aluminum material to be heated is not specifically defined. The aluminum material wound around the coil may be batch heated or it may be wound around the coil, after the coil is rewound and it is continuously heated. Preferably, heating temperature of the aluminum material in the oxidative atmosphere to be conducted in a process following addition of tensile strain would be 50 to 400° C. When the heating temperature is less than 50° C, oxidation of the surface layer of aluminum material may not be adequate and the aluminum material may not melt uniformly when the surface layer thereof is removed. When the heating temperature exceeds 400° C, oxide film of the surface layer of aluminum material will be thick, which deteriorates solubility of the aluminum material and makes it difficult to melt the aluminum material in uniform manner. Particularly preferable heating temperature would be 70 to 350° C, and 70 to 240° C, in particular. Preferably, the duration of heating in the oxidative atmosphere to be conducted in a process following addition of tensile strain would be not less than 3 seconds and not more than 72 hr. If the heating time is less than 3 seconds, the surface layer of aluminum material may not be oxidized adequately and the aluminummaterial may not dissolve uniformly when the surface layer is removed. When the heating time exceeds 72 hr, melting uniformity during removal of the surface layer of aluminummaterial becomes almost flat, and thus cost will be higher due to energy consumption during heating. Preferable heating time, in particular, would be not less than 10 seconds and not more than 48 hr, and particularly, not less than 70 seconds and not more than 48 hr. Preferably, oxygen concentration in the oxidative atmosphere during heating of aluminum material in the oxidative atmosphere to be conducted in a process following addition of tensile strain would be not less than 0.1 volume % . If the oxygen concentration is less than 0.1 volume %, the surface of aluminum material may not be adequately oxidized when it is heated. Preferably, the oxygen concentration would be not less than 1 volume %, in particular. More preferably, it would be not less than 5 volume %, in particular, and air can be preferably used as the oxidative atmosphere. Although a cleaning liquid to be used in removing the surface layer of aluminum material by washing is not specifically defined, alkaline solution or acid aqueous solution may be used. Removal of the surface layer may be done with either alkaline solution or acid aqueous solution, or the surface layer may be removed with alkaline solution and then washed with acid aqueous solution. As alkali, sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate may be exemplified, and one or more alkali selected from the above alkalis may be used as cleaning liquid by being dissolved in water. As acid, one or more acid selected from hydrochloric acid, sulfuric acid, nitric acid, and acids containing elemental phosphorus shall be used. As acids including phosphorus element, orthophosphoriσ acid (hereaf er referred to as phosphoric acid) , pyrophoric acid, metaphosphoric acid, and polyphosphoric acid may be exemplified. In addition, as acid to be used in removing the surface layer of aluminum material, perchloric acid and hypochlorous acid may be used. The removal amount of the surface layer of aluminum material may be adjusted by keeping at an appropriate level concentration of alkalis or acids, temperature of alkaline or acid aqueous solution, and contact time of the aluminum material with alkaline or acid aqueous solution. In addition, in order to enhance cleaning effect of the surface layer of aluminummaterial, a surfactant or chelating agent may be added to the cleaning liquid. The removal amount of the surface layer of aluminum material by washing after heating in the oxidative atmosphere is a mean value, and would be preferably not less than 1 mm and not more than 500nm per side of the aluminum material. If the removal amount of the surface layer is less than 1 mm, removal of the oxide film on the surface layer of aluminum material may be inadequate . If the surface layer is removed by 500 nm or more, etch pit nucleation on the surface layer of aluminum material will be suppressed, thus even degrading etching characteristic and reducing capacitance. Preferably, the removal amount of the surface layer would be not less than 1.5 nm and not more than 200 nm. Although density of the oxide film on the surface layer of aluminum material differs from that of aluminum, which is metal, the removal amount of surface layer of aluminum material, D (nm) ,

in this application shall be defined as D(nm) = E X 10⁷/2.7, by

E (g/cm²) , decrease in mass per unit surface area by washing and density of aluminum, 2.7g/cm³. Although a method of bringing cleaning liquid with aluminum material is not specifically defined, immersion, contact of aluminum material with surface of cleaning liquid, spraying, etc, may be possible. Removal of the surface layer of aluminum material by washing may take place in a process after intermediate annealing and before heating in the oxidative atmosphere to be conducted after final cold rolling or application of tensile strain. The conditions of washing may be implemented to the extent of the conditions of washing after said heating in the oxidative atmosphere. In addition, the surface layer of aluminum material may be removed by washing in a process after hot rolling and before intermediate annealing. Although the cleaning liquid to be used in a process after hot rolling and before intermediate annealing may be selected in accordance with the intended use, and shall not be specifically defined, it may be same as the cleaning liquid to be used in washing after said heating in the oxidative atmosphere. The process atmosphere during final annealing of aluminum material, area fraction of cube orientation of the aluminum material after final annealing, a method of final annealing, and temperature, time, temperature rising speed/pattern during annealing are same as those described in the manufacturing process on the said first embodiment.

[Manufacturing process on a Fifth Embodiment (Till end of final annealing) ] Manufacture of aluminum material, although it is not limited, takes place in the order of adjustment of soluble components of aluminum material/slab casting, hot rolling, cold rolling, intermediate annealing in the oxidative atmosphere, tensile strain application, and final annealing. Prior to the final annealing, after the intermediate annealing, aluminum material has its surface layer removed by washing. The removal of surface layer of aluminum material by washing may be carried out at least once. For instance, aluminum material may be washed before the tensile strain application after the intermediate annealing in the oxidative atmosphere, and then, aluminummaterial may be washed before the final annealing after the tensile strain application. In addition to the above manufacturing process, it is more preferable that aluminum material is heated in oxidative atmosphere before final annealing after tensile strain application. When aluminum material is heated in oxidative atmosphere before final annealing after tensile strain application, removal of surface layer of aluminum material by washing is carried out before final annealing after heating in the oxidative atmosphere. The surface of aluminum material may be removed before heating in oxidative atmosphere after intermediate annealing in oxidative atmosphere, and before final annealing after heating in oxidative atmosphere, respectively. The heating in the oxidative atmosphere before final annealing after tensile strain application, and the subsequent removal of surface layer of aluminum material by washing may be carried out once, respectively. The heating in the oxidative atmosphere and the subsequent removal of surface layer of aluminum material by washing may be alternately carried out several times . The intermediate annealing in the oxidative atmosphere is conducted by atmosphere heating rather than contact with a heating body. In atmosphere heating, as aluminum material does not come in contact with the heating body, unlike heating by coming in contact with a heating body, heating leaves no wrinkle or mark. Hence, in this invention, the intermediate annealing is conducted by atmosphere heating. As a method of heating during the intermediate annealing in the oxidative atmosphere, ventilation heating, radiation heating, etc. can be exemplified. In addition, although temperature rising rate/pattern at the time of heating aluminum material in the oxidative atmosphere is not specifically limited, it should be conducted under the conditions that increase area fraction of cube orientation after the final annealing. In addition, shape of aluminum material to be heated is not speci ically limited. Aluminum material wound around the coil may be batch annealed or it may be wound around the coil, after the coil is rewound and it is continuously annealed. Preferably, oxygen concentration in the oxidative atmosphere in the intermediate annealing would be not less than 0.1 volume % . If the oxygen concentration is less than 0.1 volume %, the surface of aluminum material may not be adequately oxidized when it is heated. Preferably, the oxygen concentration would be not less than 1 volume %, in particular, and more preferably, not less than 5 volume % , and air can be preferably used as an oxidative atmosphere . If air is used as the oxidative atmosphere, there is no need to control the oxygen concentration, thereby being able to plan cost reduction of the intermediate annealing process. Preferably, the intermediate annealing temperature in the oxidative atmosphere would be not less than.200° C and not more than 320° C. The intermediate annealing falling within the said temperature range could oxidize aluminum material and achieve uniform solubility of the surface layer thereof. If the intermediate annealing temperature is less than 200° C, a sufficient organization that allows recrystallized grain with the cube orientation during final annealing to grow preferentially cannot be obtained. If it exceeds 300° C, recrystallized grains that will block preferential growth of the cube orientation grain during final annealing will grow. The intermediate annealing temperature and time that allow acquisition of the favorable area fraction of cube orientation to be obtained depend on composition of aluminum material, and the condition that allows acquisition of a high area fraction of cube orientation after final annealing should be selected. The tensile strain application is a process that is used to control a cube orientation in combination with intermediate annealing. Since the tensile strain application does not have a problem that a lot of lubricating oil adheres to the surface of aluminum material during the finish cold-rolling, the surface of aluminum material is easily oxidized when aluminum material is then heated in the oxidative atmosphere. The tensile strain application has a feature that aluminum crystal grains hardly become coarse during the final annealing compared with the finish cold-rolling even if a foil has a large thickness, and thick aluminum material is easily manufactured. Although a method for tensile strain application is not particularly limited, the method described in the patent document 2 is applicable. The tensile strain is preferably not less than 1 % and not more than 15 %. When the tensile strain is less than 1 %, sufficient stress by working that allows crystallized grain having a cube orientation during final annealing to grow preferentially cannot be obtained. When the tensile strain exceeds 15 %, aluminum material may be ruptured in a tensile process. The tensile strain may given by uniaxial tensile for giving the tensile strain in one direction to aluminum material, for instance, only in a length direction, and by biaxial tensile for giving the tensile strain in different two directions, for instance, in the length direction and a width direction . Aluminum material may be bent and deformed to generate tensile strain. The said heating in the oxidative atmosphere conducted after the tensile strain application is conducted by atmosphere heating rather than contact with a heating body. In atmosphere heating, as aluminum material does not come in contact with the heating body, unlike heating by coming in contact with a heating body, heating leaves no wrinkle or mark. Hence, this invention has adopted atmosphere heating. As a method of heating in the oxidative atmosphere after the tensile strain application, ventilation heating, radiation heating, etc. can be exemplified. In addition, shape of aluminum material to be heated is not specifically limited. Aluminum material wound around the coil may be batch heated or it may be wound around the coil, after the coil is rewound and it is continuously heated. Preferably, heating temperature of aluminum material in the oxidative atmosphere after the tensile strain application would be 50 to 400° C. When the heating temperature is less than 50° C, oxidation of the surface layer of aluminum material may not be adequate and aluminum material may not melt uniformly when the surface layer thereof is removed. When the heating temperature exceeds 400° C, oxide film of the surface layer of aluminum material will be thick, which deteriorates solubility of aluminum material and makes it difficult to melt aluminum material in uniform manner. Particularly preferable heating temperature is 70 to 350° C, and 70 to 240° C most preferably. Preferably, heating time in the oxidative atmosphere after the tensile strain application is not less than 3 sec and not more than 72 hr. If heating time is less than 3 sec, the surface layer of aluminum material may not be oxidized adequately and aluminum material may not melt uniformly when the surface layer thereof is removed. When the heating time exceeds 72 hr, melting uniformity during removal of the surface layer of aluminummaterial becomes almost flat, and thus cost will be higher due to energy consumption during heating. Preferable heating time, in particular, is not less than 10 sec and not more than 48 hr, and most preferably, not less than 70 sec and not more than 48 hr. For the heating temperature and time in the oxidative atmosphere, appropriate conditions should be selected, depending on a heating method. For instance, when aluminum material is heated with it wound around a coil, it would be preferably heated at 50 to 240° C for 30 min to 72 hr, and more preferably at 70 to 240° C for 1 to 48 hr. For the heating temperature and time in the oxidative atmosphere, appropriate conditions should be selected, depending on a heating method. For instance, when aluminum material is heated with it wound around a coil, it would be preferably heated at 50 to 240° C for 30 min to 72 hr, and more preferably at 70 to 240° C for 1 to 48 hr. In addition, when aluminum material unwound from a coil or sheet-cut aluminum material is heated, the heating

time t (hour) would be preferably 10/(1.44 X x^1-5) ≤ t ≤. 72,

where x is the heating temperature (°C). It would be more

preferably 10/(1.44 X x¹⁵) ≤ t ≤ 48.

Preferably, oxygen concentration in the oxidative atmosphere during heating of aluminum material in the oxidative atmosphere after the tensile strain application would be not less than 0.1 volume % . If the oxygen concentration is less than 0.1 volume %, the surface of aluminum material may not be adequately oxidized when it is heated. Preferably, the oxygen concentration would be not less than 1 volume %, in particular, and more preferably, not less than 5 volume %, and air can be preferably used as the oxidative atmosphere. Although cleaning fluid to be used in removing a surface layer of aluminum material by washing before, the tensile strain application after intermediate annealing in oxidative atmosphere is not specifically limited, alkaline solution or acid solution may be used. The surface layer may be removed by using either alkaline solution or acid solution, or it may be washed with acid solution after being removed with alkaline solution. As alkali, sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate, and sodium carbonate, may be exemplified, and one or more alkali selected from the above alkalis may be used as cleaning fluid by being dissolved in water. As acid, one or more acid selected from those including hydrochloric acid, sulfuriσ acid, nitric acid, and elemental phosphorus shall be used. As acids containing elemental phosphorus, orthophosphoriσ acid (hereafter referred to as phosphoric acid) , pyrophoric acid, metaphosphoric acid, and polyphosphoric acid may be exemplified. In addition, as acid to be used in removing the surface layer of aluminum material, perchloric acid and hypochlorous acid may be used. The removal amount of the surface layer of aluminum material may be adjusted by keeping at an appropriate level concentration of alkalis or acids , temperature of alkaline or acid aqueous solution, and contact time of aluminum material with alkaline or acid aqueous solution. In addition, in order to enhance cleaning effect of the surface layer of aluminum material, a surface active agent or chelating agent may be added to the cleaning fluid. The said removal amount of the surface layer of aluminum material by washing after heating in oxidative atmosphere is a mean value, and shall be preferably not less than 1 nm and not more than 500 nm per side of aluminum material. If the removal amount of the surface layer is less than 1 mm, removal of the oxide film on the surface layer of aluminum material may be inadequate. If the surface layer is removed by 500 nm or more, etch pit nucleation on the surface layer of aluminum material will be suppressed, thus even degrading etching characteristic and reducing capacitance. Preferably, the removal amount of the surface layer by washing would be not less than 1.5 nm and not more than 200 nm. Although density of the oxide film on the surface layer of aluminum material differs from that of aluminum, which is metal, the removal amount of surface layer of aluminum material, D (nm) ,

in this application, it shall be defined as D (nm) = E X 10⁷/2.7,

using E (g/cm²) , decrease in mass per unit surface area by washing and density of aluminum, 2.7g/cm³. Although a method of bringing cleaning fluid with aluminum material is not specifically limited, immersion, contact of aluminum material with surface of cleaning fluid, spraying, etc, may be possible. The removal of the surface layer of aluminum material by washing may be conducted before heating in oxidative atmosphere after the tensile strain application after intermediate annealing, and washing conditions may be conducted in the.range of the washing conditions after oxidative atmosphere heating. In addition, the surface layer of aluminum material may be removed bywashing with said cleaning fluid before the intermediate annealing after the hot rolling. Although the cleaning fluid to be used in cleaning in a process before the intermediate annealing after the hot rolling may be selected in accordance with the intended use, and shall not be specifically limited, the same cleaning fluid as that to be used in washing after the said intermediate annealing may be used. The process atmosphere during final annealing of aluminum material, area fraction of cube orientation of aluminum material after the final annealing, a method of the final annealing, and temperature, time, temperature rising rate/pattern during annealing are same as those described in the manufacturing process on the said first embodiment . [Process after Final Annealing] The thickness of aluminum material for electrolytic capacitor electrodes obtained after final annealing is not particularly specified. One having a thickness of 200μm or less and one having a thickness of 200 μm or more such a foil are also contained in the invention. Aluminum material subjected to the final annealing is etched for enhancing the enlarged area rate. Although etching process conditions are not limited particularly, it is preferable to employ a direct-current etching method. The direct-current etching method etches deeply and thickly at the core of an etch pit whose the generation is promoted during the annealing, generates many tunnel-like pits, and realizes large capacitance. Aluminum material is preferably used as an anode material by performing chemical forming after the etching process, and particularly, aluminum material is preferably used as an electrolytic capacitor electrode material for middle and high voltages. However, the use of aluminum material as a cathode material is not interfered. The electrolytic capacitor using the electrode material can realize large capacitance. Processes and process conditions other than the processes specified in the invention are not limited, and are performed according to an ordinary method. The manufacturing process of aluminum material is preferably changed with relation to the etching conditions of aluminum material. The capacitance is preferably measured according to an ordinary method, and for instance, a method can be exemplified, wherein an etched foil subjected to the formation of dielectric by anodizing is measured at 120 Hz by using a stainless plate as a counter electrode in 80 g/L of an ammonium borate solution of 30 °C.

Examples Examples and Comparative Examples of the present invention will, hereinafter, be shown.

1. First Example (corresponding to a manufacturing process related to first embodiment)

[Example using a sheet shaped aluminum material] An aluminum slab was hot-rolled, an obtained sheet was then cold-rolled, and processed by an intermediate annealing, and then was further cold-rolled for finishing to obtain an aluminum material having a thickness of 110 μm, and a purity of 99.99 mass % . And the aluminum material was cut to obtain a sheet. Table 1-1 shows types of the processes performed after cold rolling (process 1-1 to process 5-1), Table 2-1 shows conditions of the heating in the oxidative atmosphere (process 2-1) in Table 1-1, and Table 3-1 and Table 4-1 show removing conditions of the surface layer of aluminum material (process 4-1) by washing in Table 1-1. An amount of the surface layer removing of aluminum material was controlled by an immersion period to a washing liquid. An amount of the sur ace layer removing of aluminum material was controlled by an immersion period to a washing liquid, and when an acid washing is carried out after an alkali washing, an amount of removing was controlled by adjusting the immersion period to the alkali washing liquid.

Example 1-1 A hot-rolling, a cold-rolling, an intermediate annealing, and a finish cold-rolling were given sequentially to an aluminum slab. As Table 5-1 shows, the sheet-shaped aluminum material obtained having a thickness of 110 μm and a purity of 99.99% was degreased using n-hexane (process 1-1). After heating for 24 hr (process 2-1) at 150 ° C in air, an average of 10 nm of a surface layer of the aluminum material was removed (process 4-1) by immersing into a sulfuric acid solution of 20 mass % at 80 °C. Then, final annealing was given to the material at 540 ° C in. argon atmosphere for 4 hr (process 5-1) to obtain an aluminum material for electrolytic capacitor electrodes .

Example 2-1 to Example 49-1, Comparative Example 1-1 to- Comparative Example 3-1 Under conditions shown in Table 5-1 to 7-1, aluminum materials for electrolytic capacitor electrodes were obtained. The aluminum materials obtained in each of the Examples and the Comparative Examples were immersed in an aqueous solution including 1.0 mol/L of HCl and 3.5 mol/L of H₂S0₄ at 75 ° C of solution temperature. A direct-current electrolytic etching was given to the materials with a current density of 0.2 A/cm² using a solution having the same composition at the same temperature. The aluminum materials after electrolytic treatment were further immersed in the hydrochloric acid-sulfuric acid mixed aqueous solution having a same composition for 360 sec at 90 °C, and then etched foils having a thicker diameter of a pit were obtained. Formation of dielectric by anodizing was given to the obtained etched foils at a forming voltage of 270 V, according to an EIAJ standard and samples for capacitance measurement were obtained. Table 5-1 to 7-1 show relative electric capacities when capacitance of Comparative Example 3-1 is set as 100.

[Table 1-1] Process

[Table 2-1] Conditions in Process 2-1 (Heating in an oxidative atmosphere)

[Table 3-1]

Conditions in Process 4-1 (Removal of the surface layer of an aluminum material by washing)

*1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time in solutions. [Table 4-1]

Washing method Quantity of Condition removal of the number surface layer of an aluminum material

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a hydrochloric acid 17-1 aqueous solution of 5 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a sulfuric acid aqueous 18-1 solution of 5 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a nitric acid aqueous 19-1 solution of 5 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a orthophosphoric acid 20-1 aqueous solution of 5 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2. mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a hydrochloric acid 21-1 aqueous solution of 3 mass % +an sulfuric acid aqueous solution of 3 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a hydrochloric acid 22-1 aqueous solution of 3 mass % +a nitric acid aqueous solution of 3 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a hydrochloric acid . 23-1 aqueous solution of 3 mass % +an orthophosphoric acid aqueous solution of 3 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a sulfuric acid aqueous 24-1 solution of 3 mass % +a nitric acid aqueous solution of 3 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a sulfuric acid aqueous 25-1 solution of 3 mass % +an orthophosphoric acid aqueous solution of 3 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a sodium hydroxide aqueous solution of 0.2 mass % at 100 nm Condition 40°C (*l)→Rinse with water→Immerse in a nitric acid aqueous 26-1 solution of 3 mass % +an orthophosphoric acid aqueous solution of 3 mass % at 40°C for 1 minute→Rinse with water→Dry

Immerse in a hydrochloric acid aqueous solution of 8 mass % at 80°C 1.3 nm Condition (*l)→Rinse with water→Dry 27-1

Immerse in a sulfuric acid aqueous solution of 20 mass % at 80°C 10 nm Condition (*l)→Rinse with water→Dry 28-1

Immerse in a nitric acid aqueous solution of 4.5 mass % at 80°C 1.7 nm Condition (*l)→Rinse with water→Dry 29-1

Immerse in a phosphoric acid aqueous solution of 20 mass % at 80°C 10 nm Condition (*l)→Rinse with water→Dry 30-1

*1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time to solutions. [Table 5-1]

[Table 6-1]

[Table 7-1]

As is understood from results of the Tables , removing by washing of the surface layer of aluminum material, after heated in the oxidative atmosphere, after the end of cold-rolling and, before final annealing can give an aluminum. material for electrolytic capacitor electrodes having outstanding etching characteristics . On one hand, since solubility of the aluminum materials at the time of washing was uneven. Comparative Example 1-1 annealed after the surface layer removing of the aluminum material by washing without the heating in the oxidative atmosphere gave low capacitance. On the other hand, since much pollution layers and oils by the roll coating at the time rolling remain. Comparative Example 2-1 annealed without removing of the surface layer of aluminum material by the washing after the heating in the oxidative atmosphere gave a low capacitance. Although Comparative Example 3-1 heated in the oxidative atmosphere after the removing by washing of an aluminum material surface layer has a higher capacitance as compared with those in Comparative Example 1-1 and Comparative Example 2-1. It is because the surface layer of aluminum material unevenly dissolved at the time of washing was not enough equalized by heating in the oxidative atmosphere, capacitance lower than the capacitance in the Example was shown. [Example using a coiled aluminum material] A hot-rolling and a cold rolling were given to the aluminum slab of composition 102 shown in Table 8-1 , and an aluminum material coil with a width of 500 mm was obtained. And after an intermediate annealing, this aluminum material coil was cold-rolled with a 20% of rolling reduction, and an aluminum material having a thickness of 110 μm and a length of 2000 m was obtained. Subsequently, in Examples 201 to 204, the surface layer was removed by washing, after a heating in the oxidative atmosphere. In Comparative Example 201, a surface layer was removed by washing without a heating in the oxidative atmosphere. Then, to the aluminum material, a final annealing for 4 hr was given at 540 ° C in an argon atmosphere, and an aluminum material for electrolytic capacitor electrodes was obtained. Table 9-1 shows conditions of heating in the oxidative atmosphere, and Table 10-1 shows conditions of the surface layer of aluminum material removing by washing. An amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performed, the amount of removing was controlled by regulation of the immersion period into an alkali cleaning liquid. The aluminum material coils obtained in each Example and each Comparative Example were uncoiled and immersed into an aqueous solution with a liquid temperature of 75 °C including HCl of 1.0 mol/L, and H₂S0₄ of 3.5 mol/L, and subsequently, a direct current electrolytic etching was given in the aqueous solution having a same composition at a same temperature using a condition of current density 0.2 A/cm². The aluminum materials after electrolytic treatment were further immersed in the hydrochloric acid-sulfuric acid mixed aqueous solution having the above-mentioned composition for 360 sec at 90 °C, and etched foil with a thicker pit diameter was obtained. The obtained etched foil was chemically converted with a chemical conversion voltage of 270 V according to EIAJ standards to obtain a sample for capacitance measurement. Table 11-1 shows relative electrostatic capacities when the capacitance of Comparative Example 201 is set as 100.

[Table 8-1]

Si, Fe, Cu and Pb concentration of Aluminum Slab

[Table 9-1]

Conditions of heating in an oxidative atmosphere after finish cold rolling or tensile strain giving

[Table 10-1]

Conditions in washing

*101: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time to solutions.

[Table 11-1]

As is understood from results of the Tables, in Examples 201 to 204, since, before the final annealing after termination of a cold rolling, the surface layer of aluminum material was removed by washing after performing heating in an oxidizing atmosphere, aluminum material was dissolved homogenously at the time of surface layer removing, and outstanding etching characteristics and high capacitance were obtained. On the other hand, in Comparative Example 201, since heating in an oxidizing atmosphere was not performed, ununiform solubility of the aluminum material at the time of the surface layer of aluminum material removing by washing was given to show a low capacitance .

2. Second Example (corresponding to a manufacturing process concerning a second embodiment)

[Example using a sheet shaped aluminum material] As shown in Table 1-2, aluminum ingots with different composition were prepared. Table 1-2 shows concentrations of Fe, Si, and Cu included in the ingots. Plates obtained by hot-rolling of these aluminum ingots were cold-rolled, and sheet shaped aluminum materials of 130 μm in thickness were prepared. Table 2-2 shows the process after degreasing, Table 3-2 shows the conditions of the process 2-2 (intermediate annealing) in Table 2-2, and Table 4-2 and 5-2 show the conditions of the process 4-2, and the process 7-2 (aluminum material surface layer removing by washing) in Table 2-2. In addition, an amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performed, the amount of removing was controlled by regulation of the immersion period into an alkali cleaning liquid.

[Table 1-2]

Si, Fe, and Cu concentration of an aluminum ingot

[Table 2-2]

Process

[Table 3-2]

Conditions in Process 2-2 (Intermediate annealing)

[Table 4-2] Conditions in Process 4-2 and Process 7-2 (Removal of the surface layer of an aluminum material by washing)

*1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time in solutions. [Table 5-2] Conditions in Process 4-2 and Process 7-2 (Removal of the surface layer of an aluminum material by washing)

*1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time in solutions. Example 1 - 2 The aluminum ingot having Fe 0.0015 mass %, Si 0.0022 mass %, and Cu 0.0055 mass % (composition 3-2) in Table 1-2 was hot-rolled. The aluminum material with a thickness of 130 micrometer obtained by the cold rolling of the obtained plate was processed under the conditions shown in Table 6-2. That is, intermediate annealing for 18 hr was given at 260 ° C in air (process 2-2) . Then, finish cold rolling with a 20% of rolling reduction was given (process 5-2) . After a degreasing with n-hexane of the aluminum material after the finish cold rolling (process 6-2), a 4 nm of aluminum material surface layer was removed by immersion into an 80° C 20 mass % sulfuric acid aqueous solution (process 7-2) . Then, a final annealing of the aluminum material was carried out at 530 ° C in argon atmosphere for 6 hr (process 8-2) to obtain an aluminum material for electrolytic capacitor electrodes. Example 2-2 to Example 51-2 and Comparative Example 1-2 to Comparative Example 4-2 The aluminum ingots including Fe, Si, and Cu in Table 1-2 was hot-rolled, and the aluminum materials with a thickness of 130 μm obtained by a cold rolling of the obtained plates were processed under conditions of Table 6-2 to 9-2 to obtain aluminum materials for electrolytic capacitor electrodes . In Tables 6-2 to 9-2, processes 1-2 to 8-2 are corresponding to processes 1-2 to 8-2 in Table 2-2, and detailed conditions of each process are described in Tables 2-2 to 5-2, and 6-2 to 9-2. After immersion of the aluminum materials obtained in each of the Examples and Comparative Examples into a 2 mol/L H₂S0₄ aqueous solution at 80 °C of liquid temperature, they were washed with water. Next, a direct current electrolytic etching was given with a current density 0.2 A/cm² in an aqueous solution at 80 °C of liquid temperatures including 1.0 mol/L of HCl and 3.5 mol/L of H₂S0. The aluminum materials after electrolytic treatment were further immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution with the composition for 360 sec at 90 °C, and etched foils with a thicker pit diameter were obtained. The obtained etched foils were anodized with a forming voltage of 270 V according to EIAJ standards to obtain samples for capacitance measurement . Table 6-2 to Table 9-2 show relative electrostatic capacities when the capacitance of Comparative Example 1-2 is set as 100.

[Table 6-2]

o σ.

[Table 7-2]

[Table 8-2]

[Table 9-2]

As described above, an intermediate annealing of an aluminum material carries out in the oxidative atmosphere, and dissolution by washing of the surface layer of aluminum material in a process before a final annealing and after the intermediate annealing, and the subsequent final annealing, may provide an aluminum material for electrolytic capacitor electrodes with outstanding etching characteristics . On the other hand, in Comparative Example 1-2, an intermediate annealing in a 100% nitrogen atmosphere was performed, and after the finish cold rolling, the surface layer of aluminum material was removed by a washing and then a final annealing was given. In this Comparative Example 1-2, uneven solubility of the aluminum material at the time of washing, and a low capacitance was shown . Comparative Example 2-2, in which the finish cold rolling and the degreasing were carried out after the intermediate annealing in the oxidative atmosphere and then final annealing was subsequently given, showed capacitance less than that of the Example due to remaining uneven surface layer formed by the rolling process. Although an intermediate annealing was performed in the oxidative atmosphere in Comparative Example 3-2 and Comparative Example 4-2, the annealing was performed after the intermediate annealing. Therefore , since the surface layer removing by washing was not performed in a process before the final annealing, the oxide film of the surface of the aluminum materials after final annealing was thicker, and thereby excellent etching characteristics were not acquired. [Example using a coiled aluminum material] A hot-rolling and a cold rolling were given to an aluminum slab having a composition in Table 11-2 to obtain an aluminum material coil with a width of 500 mm. The contents of each composition are same as shown in Table 8-1. And each process of an intermediate annealing, a finish cold rolling, and a surface layer removing was sequentially given to the aluminum material coil under conditions in Table 11-2 to obtain an aluminum material with a thickness of 110 μm and a length of 2000 m. Subsequently, a final annealing for 4 hr was carried out at 540 °C in an argon atmosphere, and an aluminum material for electrolytic capacitor electrodes was obtained. Table 10-2 shows conditions of the intermediate annealing, and conditions of the surface layer of aluminum material removing are same as the conditions shown in Table 10-1. In addition, an amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performed, the amount of removing was controlled by regulation of the immersion period into an alkaline cleaning liquid. The aluminum material coils obtained in each the Example and Comparative Example were uncoiled and immersed in a 2 mol/L of H₂S0₄ aqueous solution at 80 °C of liquid temperature, then washed with water. Subsequently, a direct current electrolytic etching was given to the coils with a current density of 0.2 A/cm² in an aqueous solution including HCl of 1.0 mol/L, and H₂S0₄ of 3.5 mol/L at a liquid temperature 80° C. The aluminum materials after electrolytic treatment were further immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution having a same composition for 360 sec at 90 ° C to obtain etched foils with a thicker pit diameter. The obtained etched foils were anodized with a forming voltage of 270 V according to EIAJ standards to obtain samples for capacitance measurement. Table 11-2 shows relative capacitance when the capacitance of Comparative Example 401 is set as 100.

[Table 10-2]

[Table 11-2]

>-

As is understood from results of the Tables, in Examples 401 to 405, the intermediate annealing in the oxidative atmosphere was carried out, and the surface layer of the aluminum material was removed by washing before final annealing. Therefore, the aluminum material was dissolved homogenously at the time of a surface layer removing, and these Examples have outstanding etching characteristics and high electrostatic capacities . On the contrary, in Comparative Example 401, the intermediate annealing was carried out in a not less than 99.99 volume % of nitrogen atmosphere, and, subsequently the surface layer of aluminum material removing was carried out before the final annealing. Therefore, the aluminum material was not dissolved homogenously at the time of the surface layer of aluminum material removing by washing, therefore Comparative Example 401 shows a low capacitance.

3. Third Example (corresponding to Manufacturing Process

Concerning third Embodiment)

[Example using a sheet shaped aluminum material] As shown in Table 1-3, aluminum ingots with different composition were prepared. Table 1-3 shows concentrations of Fe, Si, and Cu included in the ingots. Plates obtained by hot-rolling these aluminum ingots were cold-rolled, and sheet shaped aluminum materials with a thickness of 130 μm were prepared. Table 2-3 shows conditions of a process after degreasing performed before an intermediate annealing. Table 3-3 shows conditions of a process 2-3 (intermediate annealing) in Table 2-3, Tables 4-3 and 5-3 shows conditions of a process 4-3 and a process 9-3 (aluminum material surf ce layer removing by washing) in Table 2-3 , and Table 6-3 shows conditions of a process 7-3 and a process 10-3 (heating in the oxidative atmosphere) in Table 2-3. In addition, an amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performed, the amount of removing was controlled by regulation of the immersion period into an alkali cleaning liquid.

[Table 1-3]

Si, Fe, and Cu concentration of an aluminum ingot

[Table 2-3] Process

[Table 3-3]

Conditions in Process 2-3 (Intermediate annealing)

[Table 4-3] Conditions in Process 4-3 and Process 9-2 (Removal of the surface layer of an aluminum material by washing)

*1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time in solutions. [Table 5-3] Conditions in Process 4-3 and Process 9-3 (Removal of the surface layer of an aluminum material by washing)

1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time in solutions. [Table 6-3] Conditions of Process 7-3 and Process 10-3 (Heating in an oxidative atmosphere)

Example 1 - 3 The aluminum ingot having Fe 0.0015 mass %, Si 0.0022 mass %, and Cu 0.0055 mass % (composition 3) of Table 1-3 was hot-rolled, and an aluminum material having a thickness of 130 μm obtained by cold-rolling of the obtained plate was processed under the conditions shown in Table 7-3. That is, the aluminum material was degreased with n-hexane (process 1-3), and an intermediate annealing for 18 hr was given at 260 ° C in air (process 2-3). Subsequently, a finish cold rolling with a 20% of rolling reduction was carried out (process 5-3) . After degreasing with n-hexane of the aluminum material after the finish cold rolling (process 6-3) , a heating at 150 ° C for 24 hr in air was carried out (process 7-3) . Furthermore, 10 nm of a surface layer of the aluminum material was removed by immersion into at80° C 20 mass % sulfuric acid aqueous solution (process 8-3). Subsequently, a final annealing was performed at 540 ° C in argon atmosphere for 5 hr (process 11-3), and an aluminum material for electrolytic capacitor electrodes was obtained.

Example 2-3 to Example 72-3 , Comparative Example 1-3 to Comparative Example 3-3 An aluminum ingot including Fe, Si, and Cu of Table 1-3 was hot-rolled, and an aluminum material with a thickness of 130 μm obtained by a cold rolling of the obtained plate, were processed under conditions shown in Table 7-3 to 11-3 to obtain an aluminum materials for electrolytic capacitor electrodes . In Tables 7-3 to 11-3, a process 1-3 to a process 11-3 correspond to a process 1-3 to a process 11-3 in Table 2-3. Detailed conditions of each process are conditions described in Table 2-3, and Table 3-3 to Table 6-3. The aluminum materials obtained in each of the Examples and Comparative Examples were immersed in an aqueous solution including 1.0 mol/L of HCl, and 3.5 mol/L of H₂S0₄ at 75 ° C of liquid temperature, and subsequently, a direct current electrolytic etching was given with a current density of 0.2 A/cm². The aluminum materials after electrolytic treatment were further immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution having a same composition for 360 sec at 90 °C to obtain etched foils having a thicker pit diameter. The obtained etched foils were anodized with a forming voltage of 270 V according to EIAJ standards to obtain samples for capacitance measurement. Table 7-3 to Table 11-3 show relative electrostatic capacities when the capacitance of Comparative Example 3-3 is set as 100.

[Table 7-3]

[Table 10-3]

[Table 11-3]

As described above, the intermediate annealing of the aluminum materials was carried out in the oxidative atmosphere, and after termination of a cold rolling, they were heated in the oxidative atmosphere. Subsequently, a surface layer of the aluminum materials was dissolved by washing, and then a final annealing was performed, and thus aluminum materials for electrolytic capacitor electrodes having outstanding etching characteristics might be obtained. On the other hand, in Comparative Example 1-3, the intermediate annealing was performed in a 100% nitrogen atmosphere, the surface layer of the aluminum material was removed without heating in the oxidative atmosphere by washing after the finishing rolling, and subsequently final annealing was performed. Therefore Comparative Example 1-3 shows uneven solubility of the aluminummaterial at the time of washing, and has a low capacitance. In Comparative Example 2-3, the intermediate annealing in 100% nitrogen, the finish cold rolling, and the heating in the oxidative atmosphere were carried sequentially, and subsequently, the final annealing was performed, without performing the surface layer removing of the aluminum material. Therefore, since much contamination layers and oils at the time of rolling remain. Comparative Example 2-3 shows a low capacitance. In Comparative Example 3-3, the intermediate annealing in 100% nitrogen, the finish cold rolling, and the surface layer removing of the aluminum material by washing were carried out sequentially, and, subsequently the heating was performed in the oxidative atmosphere. Therefore, the Comparative Example 3-3 has a higher capacitance as compared with Comparative Example 1-3 and Comparative Example 2-3. However, since the surface layer of the aluminum material unevenly dissolved at the time of washing was not enough equalized by heating in the oxidative atmosphere, a capacitance of the Comparative Example concerned is less than the capacitance in the Example. [Example using a coiled aluminum material] A hot-rolling and a cold rolling were given to an aluminum slab having a composition in Table 12-3 to obtain an aluminum material coil having a width of 500 mm. The contents of each composition are same as shown in Table 8-1. And processes of an intermediate annealing, a finish cold rolling, a heating in the oxidative atmosphere, and a surface layer removing were given sequentially to this aluminum material coil under conditions as shown in Table 12-3 to obtain an aluminum material having a thickness of 110 μm and a length of 2000 m. A surface layer was removed by washing in Comparative Example 301, without performing a heating in the oxidative atmosphere. Subsequently, a final annealing was performed at 540 ° C in argon atmosphere for 4 hr, and an aluminum material for electrolytic capacitor electrodes was obtained. The conditions of the intermediate annealing, the heating conditions in the oxidative atmosphere, and the conditions of the surface layer of aluminum material removing are same as the conditions shown in Table 10-2, Table 9-1, and Table 10-1, respectively. In addition, an amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performe , the amount of removing was controlled by regulation of the immersion period into an alkaline cleaning liquid. The aluminum material coils obtained in each of the Example and the Comparative Example were uncoiled and immersed in an aqueous solution including 1.0 mol/L of HCl, and 3.5 mol/L of H₂S0₄ at 75 ° C of liquid temperature, and subsequently, a direct current electrolytic etching was given with a current density 0.2 A/cm². The aluminum materials after electrolytic treatment were further

A immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution having a same composition for 360 sec at 90 °C to obtain etched foils having a thicker pit diameter. The obtained etched foils were anodized with a forming voltage of 270 V according to EIAJ standards to obtain samples for capacitance measurement. Table 12-3 shows relative electrostatic capacities when the electrostatic capacitance of Comparative Example 301 is set as 100.

[Table 12-3]

As is understood from results of the Tables, in Examples 301 to 306, the intermediate annealing in the oxidative atmosphere was carried out, after termination of the cold rolling, the heating in the oxidative atmosphere was performed before final annealing, and subsequently, the surface layer of aluminum material was removed by washing. And therefore uniform solubility of the aluminum materials at the time of a surface layer removing was acquired, and Examples 301 to 306 have outstanding etching characteristics and high capacitance. On the other hand, in Comparative Example 301, after the intermediate annealing was carried out in a not less than 99.99 volume % of nitrogen atmosphere, the surface layer of aluminum material was removed by washing without the heating in the oxidative atmosphere before the final annealing and after termination of the cold rolling. And therefore, a solubility of the aluminum material at the time of the surface layer of aluminum material removing by washing is uneven, and thus Comparative Example 301 has a low capacitance.

4. Fourth Example (corresponding to manufacturing process concerning fourth embodiment)

[Example using a sheet shaped aluminum material] A plate obtained by a hot-rolling of an aluminum slab was cold-rolled, and, subsequently an intermediate annealing was given to prepare a sheet shaped aluminum material with a purity of 99.99 mass %. Table 1-4 shows processes carried out after the intermediate annealing. Table 2-4 shows conditions of a process 3-4 (heating) in Table 1-4, and Table 3-4 and 4-4 show conditions of a process 4-4 (aluminum material surface layer removing by washing) in Table 1-4. All the thicknesses of the aluminum materials obtained after the final annealing were adjusted as 110 μm by regulation of the rolling reduction of the cold rolling performed before the intermediate annealing. In addition, an amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performed, the amount of removing was controlled by regulation of the immersion period into an alkali cleaning liquid.

[Table 1-4]

Process

* The thickness of an aluminum material obtained after final annealing was entirely set to 110 μ by adjusting the reduction of cold rolling before intermediate annealing.

[Table 2-4]

Conditions in Process 3-4 and Process 5-4 (Heating in an oxidative atmosphere)

[Table 3-4]

Conditions in Process 4-4 (Removal of the surface layer of an aluminum material by washing)

*1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time in solutions. [Table 4-4]

*1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time in solutions. A plate obtained by a hot-rolling of an aluminum slab was cold-rolled, and then an intermediate annealing was further given to obtain an aluminum material with a purity 99.99 mass %. A tensile strain was given to this aluminum material as in a description in Table 5-4 (process 1-4), and then a heating for 24 hr was performed at 150 ° C in air (process 3-4) . Subsequently, this aluminum material was washed by immersion into 80° C 20 mass % sulfuric acid aqueous solution to remove 10 nm of a surface layer (process 4-4). A final annealing was given to the aluminum material after washing at 550 ° C in argon atmosphere for 4 hr (process 6-4) , and an aluminum material for electrolytic capacitor electrodes was obtained. t

Example 2-4 to Example 45-4 , Comparative Example 1-4 to Comparative

Example 4-4 Aluminum materials for electrolytic capacitor electrodes were obtained under conditions shown in Table 5-4 and 6-4. After the aluminum materials obtained in each of the Examples and Comparative Examples were immersed in an aqueous solution including 1.0 mol/L of HCl, and 3.5 mol/L of H₂S0₄ at 75 ° C of liquid temperature, a direct current electrolytic etching was given with a current density 0.2 A/cm². The aluminum materials after electrolytic treatment were further immersed in the hydrochloric acid-sulfuric acid mixed aqueous solution having a same composition for 360 sec at 90 °C to obtain etched foils having a thicker pit diameter. The obtained etched foils were anodized with a forming voltage of 270 V according to EIAJ standards to obtain samples for capacitance measurement. Table 5-4 to 6-4 show relative electrostatic capacities when the capacitance of Comparative Example 4-4 is set as 100.

[Table 5-4]

[Table 6-4]

In Example 1-4 to 45-4 in the Table, a tensile strain was given to the aluminum materials obtained by a hot-rolling, a cold rolling, and an intermediate annealing carried out sequentially, the aluminummaterials are heated in the oxidative atmosphere after application of the tensile strain, and subsequently, the surface layer of aluminum material was dissolved by washing, and a final annealing was further given. Thereby aluminum materials for electrolytic capacitor electrodes having outstanding etching characteristics may be obtained.

On the other hand, in Comparative Example 1-4, the final annealing was performed, without the heating in the oxidative atmosphere, and the surface layer removing of the aluminum materials was performed by washing after application of tensile strain. Therefore, Comparative Example 1-4 has uneven solubility in the aluminum material surface at the time of etching, and capacitance lower than in the Example. In Comparative Example 2-4, the surface layer of aluminum material was removed without heating in the oxidative atmosphere by washing after the finish cold rolling, and then the annealing was performed, and therefore the Comparative Example has uneven solubility of the aluminum material at the time of washing. In Comparative Example 3-4, the finish cold rolling and the heating in the oxidative atmosphere were carried out sequentially, and subsequently the annealing was performed, without performing the surface layer removing of the aluminum material and therefore the Comparative Example has much contamination layers and oils at the time of rolling remained. For these reasons, each of these Comparative Examples has a low capacitance. In Comparative Example 4-4, the finish cold rolling and the surface layer removing of the aluminum material by washing were carried out sequentially, and, subsequently the heating was given in the oxidative atmosphere. The Comparative Example 4-4 thus has a higher capacitance as compared with Comparative Example 1-4 to Comparative Example 3-4. However, since the surface layer of the aluminum material dissolved unevenly at the time of washing may not be enough equalized by the heating in the oxidative atmosphere, the capacitance is less than the capacitance in the Example . [Example using a coiled aluminum material] A hot-rolling and a cold rolling were given to the aluminum slab having the composition shown in Table 7-4 to obtain an aluminum material coil with a width of 500 mm. The contents of each composition are same as shown in Table 8-1. And after the intermediate annealing was given to this aluminum material coil, under conditions as shown in Table 7-4, each process of the tensile strain application, the heating in the oxidative atmosphere, and the surface layer removing was carried sequentially to obtain an aluminum material having a thickness of 110 μm and a length of 2000 m. In Comparative Example 501, the heating in the oxidative atmosphere and the surface layer removing were not performed. Subsequently, the final annealing for 5 hr was carried out at 520 ° C in argon atmosphere to obtain an aluminum material for electrolytic capacitor electrodes . Table 7-4 shows the conditions of tensile strain application. Each condition of the heating in the oxidative atmosphere and the surface layer removing are same as conditions shown in Table 9-1 and Table 10-1, respectively. In addition, an amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performed, the amount of removing was controlled by regulation of the immersion period into an alkali cleaning liquid. Aluminum material coils obtained in each of the Examples and Comparative Examples were uncoiled and immersed in an aqueous solution including 1.0 mol/L of HCl, and 3.5 mol/L of H₂S0₄ at 75 ° C of liquid temperature, and subsequently, a direct current electrolytic etching was given with a current density 0.2 A/cm². The aluminum materials after electrolytic treatment were further immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution having a same composition for 360 sec at 90 ° C to obtain etched foils having a thicker pit diameter. The obtained etched foils were anodized with a forming voltage of 270 V according to EIAJ standards to obtain samples for capacitance measurement . Table 7-4 shows relative electrostatic capacities when the capacitance of Comparative Example 501 is set as 100. [Table 7-4]

cn

As is understood from results of the Tables, in Examples 501 to 504, after tensile strain application, the heating in oxidative atmosphere was performed before the final annealing, and subsequently the surface layer of the aluminum materials was removed by washing. For this reason, the solubility of the aluminum materials at the time of surface layer removing became uniform, and thus the Examples have outstanding etching characteristics and a high capacitance. On the other hand, in Comparative Example 501, since the heating in the oxidative atmosphere and the surface layer removing of the aluminum material by washing were not performed, the solubility of the aluminum material at the time of etching became uneven, and low capacitance is shown.

5. Fifth Example (corresponding to manufacturing process concerning Fifth embodiment)

[Example using sheet shaped aluminum material] Aluminum ingots with different composition were prepared. Table 1-5 shows concentrations of Fe and Si, and Cu included in the ingots. Plates obtained by hot-rolling of these aluminum ingots were cold-rolled, and sheet shaped aluminum materials were prepared. Table 2-5 shows processes from an intermediate annealing to a final annealing. Table 3-5 shows conditions of a process 1-5 (intermediate annealing) in Table 2-5, Table 4-5 and 5-5 show conditions of a process 2-5 and a process 6-5 (aluminum material surface layer removing by washing) in Table 2-5, and Table 6-5 shows conditions of a process 5-5 and a process 7-5 (heating in oxidative atmosphere) in Table 2-5. By adjusting a rolling reduction in the cold rolling performed before the intermediate annealing, all thicknesses of aluminum materials obtained after the final annealing were set as 110 μm. In addition, an amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performed, the amount of removing was controlled by regulation of the immersion period into an alkali cleaning liquid.

[Table 1-5]

Si and Fe and Cu concentration of an aluminum ingot

[Table 2-5]

Process

[Table 3-5]

Conditions of Process 1-5 (intermediate annealing)

[Table 4-5] Conditions in Process 2-5 and Process 6-5 (Removal of the surface layer of an aluminum material by washing)

*1: The quantity of removal of the surface layer of an aluminum material was controlled by changing immersion time in solutions. [Table 5-5] Conditions in Process 2-5 and Process 6-5 (Removal of the surface layer of an aluminum material by washing)

"1: The quantity of removal of the surface layer of an aluminum material was controlled by^' changing immersion time in solutions. [Table 6-5] Conditions in Process 5-5 and Process 7-5 (Heating in an oxidative atmosphere)

Example 1-5 A plate obtained by the hot-rolling of the aluminum ingot in Table 1-5 having Fe 0.0015 mass %, Si 0.0022 mass %, and Cu 0.0055 mass % (composition 3 - 5) was cold-rolled to obtain an aluminum material. As described in Table 7-5 the aluminum material was given the intermediate annealing for 12 hr at 260 °C in air (process 1-5, condition D-5), and subsequently, a 6% of tensile strain was given (process 3-5) . A heating was carried out to the aluminum material in air at 150 ° C for 24 hr after a tensile strain application (process 5-5 and condition H4-5), and furthermore, 10 nm of surface layer of the aluminum material was removed by immersion into a 80° C 20 mass % sulfuric acid aqueous

) solution (process 6-5, conditions 27-5). Subsequently, the final annealing for 5 hr was given to the aluminum material at 550 ° C in argon atmosphere (process 8-5) to obtain an aluminum material for electrolytic capacitor electrodes .

Example 2-5 to Example 139-5, Comparative Example 1-5 to Comparative Example 5-5 A plate obtained by hot-rolling of an ingot having a composition shown in Table 1-5 was cold-rolled to obtain an aluminum material. The aluminum m&terial was processed under conditions shown in Table 7-5 to 16-5, and aluminum materials for electrolytic capacitor electrodes were obtained. The aluminum materials obtained in each of the Examples and Comparative Examples were immersed in an aqueous solution including 1.0 mol/L of HCl, and 3.5 mol/L of H₂S0₄ at 75 ° C of liquid temperature, and subsequently, a direct current electrolytic etching was given to the aluminum materials with a current density 0.2 A/cm² in the aqueous solution having a same composition at a same temperature. The aluminum materials after electrolytic treatment were further immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution having a same composition for 360 sec at 90 °C to obtain etched foils having a thicker pit diameter. The obtained etched foils were anodized with a forming voltage of 270 V according to EIAJ standards to obtain samples for capacitance measurement. Table 7-5 to Table 16-5 show relative electrostatic capacities when the capacitance bf Comparative Example 4-5 is set as 100.

[Table 9-5]

ux

CD

σ- o

[Table 16-5]

As described above, when an aluminum material for electrolytic capacitor electrodes is manufactured in a manner wherein the hot-rolling and the cold rolling are performed, subsequently the intermediate annealing is given, tensile strain is given in a step before the start of the final annealing and after the intermediate annealing, and then the final annealing is given, the intermediate annealing is performed in the oxidative atmosphere, and a surface layer of the aluminum material is removed by washing in a process before the final annealing and after the intermediate annealing. The above-mentioned process enables realization of an aluminum material having outstanding etching characteristics. Furthermore, an aluminum material for electrolytic capacitor electrodes having more excellent etching characteristics may be obtained by sequential implementation of the heating in the oxidative atmosphere, the surface layer removing of the aluminum material by washing, and the final annealing, after the intermediate annealing in the oxidative atmosphere, and the tensile strain application. On the other hand, in Comparative Example 1-5, the intermediate annealing in a not less than 99.99 volume % of nitrogen atmosphere, and the tensile strain application were carried out sequentially, and then the final annealing was given without the surface layer of aluminum material removing by washing. Therefore, the Comparative Example 1-5 has uneven solubility in the aluminum material surface at the time of etching, and capacitance lower than in the Example. In Comparative Example 2-5, the intermediate annealing in a not less than 99.99 volume % of nitrogen atmosphere, the finish cold rolling, and the surface layer removing of the aluminum material by washing were carried out sequentially, and subsequently, the final annealing was given. In the Comparative Example 2-5, the solubility of the aluminum material at the time of washing is uneven. In Comparative Example 3-5, the intermediate annealing in a not less than 99.99 volume % of nitrogen atmosphere, the finish cold rolling, and the heating in the oxidative atmosphere were sequentially carried out, and subsequently, the final annealing was performed, without the surface layer removing of the aluminum material . Therefore, since much contamination layers and oils at the time of rolling remain in the Comparative Example 3-5, all the materials show low electrostatic capacities. In Comparative Example 4-5, the finish cold rolling, the surface layer removing of the aluminum material by washing, and the final annealing were sequentially carried out, after the intermediate annealing in a not less than 99.99 volume % of nitrogen atmosphere. Although the Comparative Example 4-5 has a higher capacitance as compared with the electrostatic capacities of Comparative Example 1-5 to Comparative Example 3-5, the value is less than that in the Example, because the surface layer of the aluminum material dissolved unevenly at the time of washing is not enough equalized by the heating in the oxidative atmosphere. In Comparative Example 5-5 , after the intermediate annealing in the oxidative atmosphere, the finish cold rolling was performed and then the final annealing was performed.

Since the surface layer of aluminum material removing by washing is not performed, the Comparative Example 5-5 has a thicker aluminum material surface oxide film and a low capacitance. [Example using coiled aluminum material] A hot-rolling and a cold rolling were given to an aluminum slab having a composition shown in Table 17-5 to obtain an aluminum material coil having a width of 500 mm. The contents of each composition are same as shown in Table 8-1. And to this aluminum material coil, each process of the intermediate annealing, the tensile strain application, the heating in the oxidative atmosphere , and the surface layer removing was sequentially carried out under conditions as shown in Table 17-5 to obtain an aluminum material having a thickness of 110 μm and a length of 2000 m. In addition, the heating in the oxidative atmosphere was not performed in Example 607 and Comparative Example 601, and furthermore in Comparative Example 601, the surface layer removing was not carried out . Subsequently, the final annealing for 4 hr was carried out at 540 ° C in argon atmosphere to obtain an aluminum material for electrolytic capacitor electrodes . The conditions of the intermediate annealing, the tensile strain application, the heating in the oxidative atmosphere, and the surface layer removing are same as conditions shown in Table 10-2, Table 17-5, Table 9-1, and Table 10-1, respectively. In addition, an amount of the surface layer removing of the aluminum materials was controlled by an immersion period into a washing liquid, and in case of an acid cleaning after an alkali cleaning performed, the amount of removing was controlled by regulation of the immersion period into an alkali cleaning liquid. The aluminum material coils obtained in the Examples and Comparative Examples were uncoiled and immersed respectively in an aqueous solution including 1.0 mol/L of HCl and 3.5mol/L of H₂S0 at 75 °C of liquid temperature, and subsequently, a direct current electrolytic etching was given to the aluminum materials with a current density 0.2 A/cm² in the aqueous solution having a same composition at a same temperature. The aluminum materials after electrolytic treatment were further immersed in a hydrochloric acid-sulfuric acid mixed aqueous solution having a same composition for 360 sec at 90 ° C to obtain etched foils having a thicker pit diameter. The obtained etched foils were anodized with a forming voltage of 270 V according to EIAJ standards to obtain samples for capacitance measurement. Table 17-5 shows relative electrostatic capacities when the capacitance of Comparative Example 601 is set as 100.

[Table 17-5]

As is understood from results of the Tables, In Example 607, the intermediate annealing in the oxidative atmosphere was carried out , and the surface layer of aluminum material was removed by washing before the final annealing. Therefore, the solubility of the aluminum material at the time of surface layer removing becomes uniform, and the Example 607 has outstanding etching characteristics and a high capacitance. In Examples 601 to 606, the tensile strain application, the heating in the oxidative atmosphere, the surface layer removing of the aluminum materials by washing, and the final annealing were sequentially carried out after the intermediate annealing in the oxidative atmosphere. In Examples 601 to 606, the solubility of the aluminum materials at the time of the surface layer removing became more uniform, further excellent etching characteristics, and high electrostatic capacities were realized. On the contrary, in Comparative Example 601, the tensile strain application and the final annealing were sequentially carried out after the intermediate annealing in a not less than 99.99 volume % of nitrogen atmosphere. In the Comparative Example 601, the solubility of the aluminum material at the time of the surface layer of aluminum material removing during etching was uneven, and a low capacitance was shown. Terms and descriptions as used herein are intended to describe embodiments concerning the present invention, and the invention is not intended to be limited to these terms and descriptions. The invention permits any designing modification, unless deviated from spirits of the invention, as long as it is within the limits of Claims.

Industrial Applicability The manufacturing method of an aluminum material for electrolytic capacitor electrodes of the invention may be used for manufacturing electrode materials of aluminum electrolytic capacitors used as electrical components and electronic parts.

Claims

1. A method for manufacturing an aluminum material for electrolytic capacitor electrodes including the steps of hot-rolling, cold-rolling and final annealing, comprising the steps of: heating an aluminum material in oxidative atmosphere after the hot-rolling and before commencing final annealing; removing the surface layer of the aluminum material by washing after the heating; and, subjecting the washed aluminum material to the final annealing.

2. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 1, wherein heating of the aluminum material in oxidative atmosphere and removing of the surface layer by washing are conducted after finishing the cold-rolling.

3. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 1 or 2 , wherein a cleaning liquid used for washing is an alkaline aqueous solution.

4. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 1 or 2, wherein the cleaning liquid used for washing is an acid aqueous solution.

5. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 1 or 2 , wherein the aluminum material is sequentially washed by the alkaline aqueous solution and by the acid aqueous solution.

6. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claims 3 or 5, wherein an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate.

7. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 4 or 5 , wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphorus-containing acid.

8. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 7 , wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing after heating in the oxidative atmosphere is not less than 1 nm, and not more than 500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) xlO⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum.

9. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 8, wherein the heating temperature in the oxidative atmosphere is within the range of 50 to 400 °C.

10. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 9, wherein the heating time in the oxidative atmosphere is not less than 3 sec, and not more than 72 hr.

11. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 10, wherein the oxygen concentration in the oxidative atmosphere during heating is 0.1 volume % or more.

12. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 11, further comprising the step of degreasing the aluminum material before heating the aluminum material in the oxidative atmosphere, or after heating the aluminummaterial in the oxidative atmosphere before washing the surface layer of the aluminum material.

13. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 12, wherein the aluminum material is degreased by using an organic solvent .

14. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 12, wherein the aluminum material is degreased by using water added with a surfactant .

15. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 1, wherein the aluminum material is subjected to intermediate annealing during the cold-rolling and subjected to finish cold-rolling after intermediate annealing; wherein the intermediate annealing is conducted in oxidative atmosphere, and the removing of the surface layer of the aluminum material by washing is conducted after the intermediate annealing.

16. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 15, wherein the surface layer of the aluminum material is removed by washing the aluminum material after the finish cold-rolling before the final annealing.

17. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 15, wherein the surface layer of the aluminum material is removed by washing the aluminum material after the intermediate annealing before the finish cold-rolling.

18. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 15 to 17, wherein the oxygen concentration in the oxidative atmosphere during the intermediate annealing is 0.1 volume % or more.

19. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 15 to 18, wherein the aluminum material is subjected to the intermediate annealing in the oxidative atmosphere at a temperature not less than 200 °C, and not more than 320 °C.

20. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 15 to 19, wherein the cleaning liquid used for washing is the alkaline aqueous solution.

21. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 15 to 19, wherein the cleaning liquid used for washing is the acid aqueous solution.

22. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 15 to 19, wherein the aluminum material is sequentially washed by the alkaline aqueous solution and the acid aqueous solution.

23. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 20 to 22, wherein an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate.

24. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 21 or 22, wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphorus-containing acid.

25. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 15 to 24, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing is not less than 1 nm, and not more than 500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) xlO⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum.

26. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 15 to 25, further comprising the step of degreasing the aluminum material after the cold-rolling before the intermediate annealing, before the final annealing.

27. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 26, wherein the aluminum material is degreased by using an organic solvent.

28. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 26, wherein the aluminum material is degreased by using water added with a surfactant .

29. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 1 , wherein the aluminum material is subjected to an intermediate annealing during the cold-rolling and subjected to a finish cold-rolling after the intermediate annealing; wherein the intermediate annealing is conducted in an oxidative atmosphere, and the heating of the aluminum material in the oxidative atmosphere and the removing of the surface layer by washing are conducted after the finish cold-rolling.

30. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 29, comprising the step of removing the surface of the aluminum material by washing the aluminum material after the intermediate annealing and before the finish cold-rolling.

31. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 29 or 30, wherein the cleaning liquid used for washing is the alkaline aqueous solution.

32. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 29 or 30, wherein the cleaning liquid used for washing is the acid aqueous solution.

33. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 29 or 30, wherein the aluminum material is sequentially washed by the alkaline aqueous solution and the acid aqueous solution.

34. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 31 to 33, wherein an alkali in alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate.

35. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 32 or 33, wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and a phosphorus-containing acid.

36. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 29 to 35, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing after heating in the oxidative atmosphere after the finish cold-rolling is not less than 1 nm, and not more than 500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) χl0⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum.

37. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 29 to 36, wherein the heating temperature in the oxidative atmosphere after the finish cold-rolling is within the range of 50 to 400 °C.

38. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 37, wherein the heating time in the oxidative atmosphere after the finish cold-rolling is not less than 3 sec, and not more than 72 hr.

39. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 29 to 38, wherein aluminum material is subjected to the intermediate annealing in the oxidative atmosphere at a temperature not less than 200 °C, and not more than 320 °C.

40. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 29 to 39, wherein the oxygen concentration in the oxidative atmosphere during heating after the finish cold-rolling is 0.1 volume % or more.

41. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 29 to 40, wherein the oxygen concentration in the oxidative atmosphere during the intermediate annealing is 0.1 volume % or more.

42. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 29 to 41, further comprising the step of degreasing. the aluminum material before the intermediate annealing after the cold-rolling, before finally removing the surface layer of the aluminum material by washing the aluminum material.

43. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 42, wherein the aluminum material is degreased by using an organic solvent.

44. The method, for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 42 , wherein the aluminum material is degreased by using water containing a surfactant .

45. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 1 , wherein the aluminum material is subjected to an intermediate annealing after the cold-rolling and tensile-strained after the intermediate annealing and before commencing the final annealing; and the heating of the aluminum material in the oxidative atmosphere and the removing of the surface layer of the aluminum material by washing are conducted after giving the tensile strain.

46. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 45, wherein the cleaning liquid used for washing is the alkaline aqueous solution.

47. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 45, wherein the cleaning liquid used for washing is the acid aqueous solution.

48. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 45, wherein the aluminum material is sequentially washed by the alkaline aqueous solution and the acid aqueous solution.

49. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 46 to 48, wherein an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate.

50. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 47 or 48, wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and a phosphorus-containing acid.

51. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 45 to 50, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing after heating in the oxidative atmosphere is not less than 1 nm, and not more than 500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) χl0⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum.

52. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 45 to 51, wherein the heating temperature in the oxidative atmosphere is within the range of 50 to 400 °C.

53. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 52, wherein the heating time in the oxidative atmosphere is not less than 3 sec, and not more than 72 hr.

54. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 45 to 53, wherein the oxygen concentration in the oxidative atmosphere during heating is 0.1 volume % or more.

55. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 1 , wherein the aluminum material is subjected to intermediate annealing in oxidative atmosphere after cold-rolling and tensile strain application after the intermediate annealing and before commencing the final annealing; and the removing of the surface layer of the aluminum material by washing is conducted at least one time after the intermediate annealing.

56. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 55, wherein the surface layer of the aluminum material is removed by washing the aluminum material after the tensile strain application before the final annealing.

57. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 55, wherein the surface layer of the aluminum material is removed by washing the aluminum material after the intermediate annealing before the tensile strain application.

58. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 55 to 57, wherein the surface layer of the aluminum material is removed by washing the aluminum material after the tensile strain application before the final annealing, after heating the aluminum material in the oxidative atmosphere.

59. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 55 to 58, wherein the cleaning liquid used for washing is the alkaline aqueous solution.

60. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 55 to 58, wherein the. cleaning liquid used for washing is the acid aqueous solution.

61. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 55 to 58, wherein the aluminum material is sequentially washed by the alkaline aqueous solution and the acid aqueous solution.

62. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 59 to 61, wherein an alkali in the alkaline aqueous solution is one or more alkali selected from the group consisting of sodium hydroxide, calcium hydroxide, potassium hydroxide, sodium o-silicate, sodium m-silicate, sodium tertiary phosphate and sodium carbonate.

63. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 60 or 61, wherein an acid in the acid aqueous solution is one or more acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and a phosphor element.

64. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 55 to 63, wherein the average quantity of removal of the surface layer of the aluminum material obtained by washing after heating in the oxidative atmosphere after intermediate annealing is not less than 1 nm, and not more than 500 nm per the single-side of the aluminum material in the quantity of removal D (nm) specified below: quantity of removal D (nm)=E(g/cm²) xlO⁷/ 2.7 (g/cm³), where E is the decrease of mass per unit surface area by washing, and 2.7 g/cm³ is the density of aluminum.

65. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 57 to 64, wherein the heating temperature in the oxidative atmosphere after the tensile strain application is within the range of 50 to 400 °C.

66. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to claim 65, wherein the heating time in the oxidative atmosphere after the tensile strain application is not less than 3 sec, and not more than 72 hr.

67. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 55 to 66, wherein the intermediate annealing in the oxidative atmosphere is performed at a temperature not less than 200 °C, and not more than 300 °C.

68. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 55 to 67, wherein the oxygen concentration in the oxidative atmosphere during heating after the tensile strain application is 0.1 volume % or more.

69. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 55 to 67, wherein the oxygen concentration in the oxidative atmosphere during the intermediate annealing is 0.1 volume % or more.

70. The method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 69, wherein the aluminum material is subjected to the final annealing in inert gas atmosphere.

71. A method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 70, wherein the aluminum material is subjected to the final annealing at a temperature not less than 450 ° C, and not more than 600 °C.

72. A method for manufacturing an aluminum material for electrolytic capacitor electrodes according to any one of claims 1 to 71, wherein the aluminum purity of the aluminum material is 99.9 mass % or more.

73. The aluminum material for electrolytic capacitor electrodes manufactured by the method according to any one of claims 1 to 72.

74. The aluminum material for electrolytic capacitor electrodes according to claim 73, wherein the aluminum material is an anode material for middle or high voltages

75. The method for manufacturing an electrode material for electrolytic capacitors, comprising the step of etching the aluminum material manufactured by any one of claims 1 to 72.

76. The method for manufacturing an electrode material for electrolytic capacitors according to claim 75, further comprising the step of performing formation of dielectric by anodizing after etching.

77. The method for manufacturing an electrode material for electrolytic capacitors according to claim 75 or 76, wherein at least a part of the etching is DC electrolytic etching.

78. The anode material for aluminum electrolytic capacitors manufactured by the method according to any one of claims 75 to 77.

79. The aluminum electrolytic capacitor comprising the aluminum electrode material manufactured by the method according to any one of claims 75 to 77 as electrode materials.