MANUFACTURE OF BATTERY SEPARATOR

PROBLEM TO BE SOLVED: To accurately divide a hydrophilic region and a water repellent region, and divide both regions with a fine pattern by irradiating light to only the specified region of the surface of the prescribed olefin resin fiber nonwoven fabric. SOLUTION: Semiconductor fine particles are carried on the surface of an olefin resin fiber, and light is radiated to the prescribed region on the surface to make the irradiated part hydrophilic. Since the semiconductor fine particles absorb light having energy higher than the band gap, electrons in a valance band are excited, and a positive hole is produced in the valance band. The positive hole-excited electron react with adsorbed water or oxygen on the surface of the semiconductor fine particle, and an active oxygen species such as O2 , O2 H, and an HO radical is produced. A methylene group or a methyl group covering the fiber surface is effectively oxidized by the active oxygen species, and converted into a hydroxyl group or a carbonyl group having hydrophilic property. A region not irradiated is left as the water repellent region.