METHOD FOR MANUFACTURING OPTICAL FILM

• Main Authors: MORI SATOSHI, TAKIMOTO MASATAKA, TAKAGI TAKAHIRO
• Format: Patent
• Language: English; Japanese
• Published: 22.06.2017
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CHEMISTRY; COMPOSITIONS BASED THEREON; DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; GENERAL PROCESSES OF COMPOUNDING; METALLURGY; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICAL LOGIC ELEMENTS; OPTICS; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; PHYSICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; 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 an optical film capable of sufficiently reducing the absolute value of retardation without increasing haze and sufficiently suppressing cracks when a polarizer is punched.SOLUTION: The method for manufacturing an optical film comprises: the first step of obtaining a solution including a cycloolefin based polymer including a structural unit derived from a cycloolefin monomer represented by the general formula (A-1) and a solvent; the second step of casting the solution on a support and peeling a filmy material dried until the amount of residue solvent is 30-70 mass%; and the third step of drying the peeled filmy material without being stretched or while being stretched with a stretch ratio of 10% or less to obtain an optical film having 0 nm or more and 3 nm or less of a retardation Ro in the in-plane direction and -5nm or more and 5nm or less of a retardation Rt in the thickness direction, measured at a measurement wavelength of 550 nm in an environment at 23°C and 55% RH.SELECTED DRAWING: Figure 1A 【課題】ヘイズを増大させることなく、位相差の絶対値を十分に低くすることができ、且つ偏光板の打ち抜き加工時のクラックを十分に抑制できる光学フィルムを提供する。【解決手段】一般式（Ａ−１）で表されるシクロオレフィン単量体由来の構成単位を含むシクロオレフィン系重合体と溶媒とを含む溶液を得る第１の工程と、前記溶液を、支持体上に流延した後、残留溶媒量が３０〜７０質量％となるまで乾燥させた膜状物を剥離する第２の工程と、剥離された前記膜状物を、延伸することなく乾燥するか、又は延伸倍率１０％以下で延伸しながら乾燥させて、測定波長５５０ｎｍ、２３℃５５％ＲＨの環境下で測定され、面内方向の位相差Ｒｏが０ｎｍ以上３ｎｍ以下であり、厚み方向の位相差Ｒｔが−５ｎｍ以上５ｎｍ以下である光学フィルムを得る第３の工程とを含む、光学フィルムの製造方法。【選択図】図１Ａ