METHOD OF PRODUCING BATTERY SEPARATOR USING SURFACE MODIFICATION TREATMENT

PROBLEM TO BE SOLVED: To provide a method of producing a battery separator using surface modification treatment, which produces the battery separator by a dry process, satisfies air permeability and puncture strength properties required in the battery separator, and improves thermal shrinkage and wettability, thereby appropriately responding to the trend for high-capacity and compact batteries.SOLUTION: A method of producing a battery separator using surface modification treatment includes the steps of: forming an unstretched sheet; subjecting the unstretched sheet to heat forming; cold-stretching the sheet subjected to the heat forming; hot-stretching the cold-stretched film by first hot stretching and second hot stretching; and heat-setting the film subjected to the second hot stretching. The method further includes a step of performing corona discharge treatment between the steps of the first hot stretching and the heat setting.SELECTED DRAWING: Figure 1 【課題】乾式工程で製造され、電池のセパレータにおいて求められる通気性及び突刺強度の特性を満たし、熱収縮率及び濡れ性を改善させ、電池の高容量及びコンパクト化に適宜対応する表面改質処理を用いた電池用セパレータの製造方法を提供する。【解決手段】未延伸シートを形成する段階と、未延伸シートを熱成形する段階と、熱成形されたシートを低温延伸する段階と、低温延伸されたフィルムを１次高温延伸及び２次高温延伸で高温延伸する段階と、２次高温延伸されたフィルムを熱固定する段階と、を含み、１次高温延伸する段階と熱固定する段階との間にコロナ放電処理を行う段階を含む。【選択図】図１