Method for producing aluminum foil for capacitor and solid electrolytic capacitor

The solid electrolytic capacitor as claimed in clam 23, wherein said monomer compound containing a 5-membered heterocyclic ring is a compound represented by the following formula (I):

• wherein the substituents R1 and R2 each independently represents a monovalent group selected from the group consisting of a hydrogen atom, a linear or branched, saturated or unsaturated hydrocarbon group having from 1 to 10 carbon atoms, an alkoxy group, an alkyl ester group, a halogen, a nitro group, a cyano group, a primary, secondary or tertiary amino group, a CF3 group, a phenyl group and a substituted phenyl group;
• the hydrocarbon chains of R1 and R2 may combine with each other at an arbitrary position to form a divalent chain for forming at least one 3-, 4-, 5-, 6- or 7-membered saturated or unsaturated hydrocarbon ring structure together with the carbon atoms substituted by these substituents;
• and the ring bonding chain may optionally contain a bond such as carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl or imino.