TWI778238B

A separator according to the present invention is composed only of non-fibrillated fibers; and this separator contains 20-60% by mass of polyester main body fibers and 10-70% by mass of polyester binder fibers as the non-fibrillated fibers, while containing 10-30% by mass of a polyvinyl alcohol as a binder material. Consequently, the average pore diameter of the separator is able to be controlled to 5.0-20.0 μm, the frequency of pore diameters within the range of 5.0-15.0 μm is able to be controlled to 70% or more of all pore diameters, and the frequency of pore diameters of 20 μm or more is able to be controlled to 10% or less, thereby enabling the separator to have high uniformity. In addition, by using this separator in a solid electrolytic capacitor or in a hybrid electrolytic capacitor, the present invention is able to provide an aluminum electrolytic capacitor which has improved capacitance characteristics by enhancing the impregnation ability of a polymerization liquid or dispersion liquid of a conduct