PRODUCTION METHOD OF THERMOPLASTIC RESIN FILM

• Main Authors: SUZUKI TOSHIHIKO, KAGEYAMA HITOSHI, ISHIGAMI YOSHITERU
• Format: Patent
• Language: English; Japanese
• Published: 12.02.2015
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

PROBLEM TO BE SOLVED: To provide a method for producing a thermoplastic resin film, by which a birefringence value of a film after stretched can be minimized.SOLUTION: The method for producing a thermoplastic resin film includes steps of: heating and melting a thermoplastic resin in an extruder; extruding the heated and melted thermoplastic resin (melt resin) from a discharge port of a die of the extruder into a film state using a die, the lip land of which is inclined by 10° to 60° with extension line of the lip land used as a reference, where the die is so set that an extension line of the lip land of the die intersects perpendicularly to an installation surface of the extruder; and drawing the melt resin by use of a cooling roll such that the following conditions are satisfied: an acute angle formed by intersecting a straight line that passes through the discharge port of the die and a contact point where the melt resin first comes into contact with the cooling roll, with a tangential line of the cooling roll surface, the tangential line passing through the discharge port of the die, is 0° or more and 40° or less; and a temperature (Ta [°C]) of the melt resin at the discharge port of the die, a rotational speed (Ls [m/min]) of the cooling roll, and a melt peak temperature (T[°C]) of the thermoplastic resin satisfy a relationship of Ta≥4.6Ls+Tm+95. 【課題】延伸後の複屈折の値を小さくできる熱可塑性樹脂製フィルムを製造する方法を提供する。【解決手段】熱可塑性樹脂を押出機で加熱溶融し、ダイのリップランドの延長線と押出機設置面とが垂直に交わるようにダイを設置した場合のリップランドの延長線を基準として、リップランドが１０−６０?傾いているダイを用いて、加熱溶融された熱可塑性樹脂（溶融樹脂）を押出機のダイの吐出口からフィルム状に押出し、ダイの吐出口と溶融樹脂が最初に冷却ロールに接する点とを通る直線と、ダイの吐出口を通る冷却ロール表面の接線とが交差して形成される鋭角が０?以上４０?以下であり、ダイの吐出口の溶融樹脂の温度（Ｔａ［℃］）と冷却ロールの回転速度（Ｌｓ［ｍ／分］）と熱可塑性樹脂の融解ピーク温度（Ｔｍ［℃］）とが、Ｔａ ４．６Ｌｓ＋Ｔｍ＋９５の関係を満たすように溶融樹脂を冷却ロールで引取って熱可塑性樹脂製フィルムを製造する方法。【選択図】図１