Process for producing aluminum electrode foil for capacitor and aluminum foil for etching

1. A process for producing an aluminum electrode foil for a capacitor, the process comprising:

a first step for preparing an emulsion from a mixture including a first phase of a liquid at least containing a resin, a second phase of a liquid that is incompatible with the first phase, and an emulsifier;

a second step for coating the emulsion on a surface of an aluminum foil;

a third step for removing the second phase to form a resin film having a plurality of pores on its surface;

a fourth step for etching the aluminum foil having the resin film formed thereon; and

a fifth step for removing the resin film after the etching.

2. The process of claim 1 , wherein the first phase includes a liquid resin or a resin solution obtained by dissolving a resin in a solvent, the mixture further includes a cross-linking agent, and the third step includes cross-linking the liquid resin or the dissolved resin.

3. The process of claim 1 , wherein the first step includes stirring and dispersing the mixture by using a homogenizer or a jet mill.

4. The process of claim 1 , wherein the second step includes coating the emulsion by using any one of a die coater, gravure printing, a reverse roll, and a bar coater.

5. The process of claim 1 , wherein the third step includes removing the second phase by using a solvent for dissolving the liquid of the second phase.

6. The process of claim 1 , wherein the third step is evaporating the liquid of the second phase by heating.

7. The process of claim 1 , wherein the aluminum foil is high purity aluminum with a purity of 99.99% or more.

8. The process of claim 1 , wherein the aluminum foil is aluminum with (100) orientation of 85% or more.

9. The process of claim 1 , wherein the first step includes preparing an emulsion in a form in which particles of the second phase are individually dispersed in a liquid that is the first phase.

10. The process of claim 9 , wherein a diameter of the particles of the second phase is in a range from 0.05 to 10 μm.

11. The process of claim 9 , wherein an interval between particles of the second phase is in a range from 0.01 to 10 μm.

12. The process of claim 1 , wherein the first phase is a resin solution obtained by dissolving a water-insoluble resin in any one of organic solvent from ketone, ester and hydrocarbon, and the second phase is water.

13. The process of claim 12 , wherein a boiling point of the solvent in the first phase is lower than 100° C.

14. The process of claim 12 , wherein the water-insoluble resin includes at least one of a polyester resin, a phenol resin, a silicon resin, an acrylic resin, a polyimide resin, and butyral resin.

15. The process of claim 1 , wherein the first phase includes a liquid resin or a resin solution obtained by dissolving a resin in a solvent, the resin included in the first phase is a water soluble resin, the second phase is aliphatic hydrocarbon, and the third step includes cross-linking the water soluble resin so as to be insolubilized in water.

16. The process of claim 15 , wherein a boiling point of the liquid in the second phase is higher than 100° C.

17. The process of claim 15 , wherein the water soluble resin is a resin including at least one of an isobutylene-maleic anhydride copolymer, cellulose, polyvinyl alcohol, polyethylene oxide, polyacrylamide and polyvinylpyrrolidone.

18. The process of claim 15 , wherein the second phase includes at least one of octane, nonane, decane, dodecane and trimethylhexane.