METHOD FOR PRODUCING POLYOLEFIN MICROPOROUS FILM, BATTERY SEPARATOR, AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

• Main Authors: FUKUNAGA YUKI, IMAI SHOJI
• Format: Patent
• Language: English; Japanese
• Published: 04.10.2018
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; BASIC ELECTRIC ELEMENTS; CHEMISTRY; COMPOSITIONS BASED THEREON; ELECTRICITY; GENERAL PROCESSES OF COMPOUNDING; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL; WORKING-UP

PROBLEM TO BE SOLVED: To provide a method for producing a polyolefin microporous film having good cycle characteristics and excellent in electrolyte injection property; a battery separator obtained by the production method; a nonaqueous electrolyte secondary battery having the battery separator.SOLUTION: A method for producing a polyolefin microporous film includes: a step 1 of kneading a polyolefin resin and a plasticizer to form a kneaded product; a step 2 of processing the kneaded product into a sheet-like molded body; a step 3 of rolling the sheet-like molded body to obtain a rolled body; and a step 4 of extracting a plasticizer from the rolled body and stretching the rolled body, where in the step 3, a film thickness maintenance rate which is defined as film thickness maintenance rate=(film thickness after rolling/film thickness before rolling)×100, is 35% or more and 90% or less.SELECTED DRAWING: None 【課題】サイクル特性が良好であり、且つ、電解液注液性に優れるポリオレフィン微多孔膜の製造方法、該製造方法により得られる電池用セパレータ、及び該電池用セパレータを備える非水電解液二次電池を提供することを目的とする。【解決手段】ポリオレフィン樹脂及び可塑剤を混練して混練物を形成する工程１と、前記混練物をシート状成形体に加工する工程２と、前記シート状成形体を圧延し圧延体とする工程３と、前記圧延体から可塑剤を抽出する工程、及び前記圧延体を延伸する工程を有する工程４を有し、前記工程３において、膜厚維持率＝（圧延後膜厚／圧延前膜厚）×１００で定義される膜厚維持率が３５％以上９０％以下である、ポリオレフィン微多孔膜の製造方法。【選択図】 なし