BIAXIALLY ORIENTATED POLYESTER FILM

• Main Authors: MURASHIGE RYUICHI, KONAGAYA JUJI, MATSUMOTO HARUO
• Format: Patent
• Language: English
• Published: 23.03.1993
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CHEMISTRY; COMPOSITIONS BASED THEREON; COMPOSITIONS OF MACROMOLECULAR COMPOUNDS; GENERAL PROCESSES OF COMPOUNDING; INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULARARTICLES; INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; USE OF INORGANIC OR NON-MACROMOLECULAR ORGANIC SUBSTANCES ASCOMPOUNDING INGREDIENTS; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL; WORKING-UP

PURPOSE:To obtain the title film useful as a base for high-quality magnetic tape, having excellent surface smoothness and improved slipperiness, comprising specific amounts of colloidal silica containing an alkali metal oxide and having a specific average particle diameter and inert particles. CONSTITUTION:0.05-0.5wt.% colloidal silica containing 0.004-0.02mol calculated as an alkali metal oxide of an alkali metal compound (e.g. sodium oxide) based on 100g colloidal silica and having 0.15-0.45mu average particle diameter and 0.0001-0.0019wt.% inert particles (e.g. spherical calcium carbonate) having 0.5-1.5mum average particle diameter are added to a mixture of terephthalic acid, ethylene glycol and antimony trioxide in an esterification reactor, subjected to polycondensation reaction at 285 deg.C under 0.1mmHg for three hours while stirring a formed polyester is extrusion molded in a molten state at 290 deg.C into a sheetlike state, biaxially orientated and heat-treated to give the objective biaxially orientated polyester film having excellent surface smoothness and improved slipperiness.