METHOD FOR CLEANING FILTER USED FOR FILTERING POLYESTER CONSTITUENT, AND METHOD FOR MANUFACTURING POLYESTER FILM USED FOR MAGNETIC RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide an effective method for cleaning a filter when a polyester film used for a magnetic recording medium for producing a DVC tape with few dropouts, especially few dropouts over an extended area is manufactured, and a method for manufacturing a film using the filter cleaned by the cleaning method. SOLUTION: The filter is made of sintered metal fibers and its filtering accuracy is equal to or smaller than 2.0μm. After a polyester constituent deposited on the filter is heated and decomposed in the presence of water or a compound with hydroxyl group, foreign materials are removed by vibrating the filter mechanically and making liquid or gas pass through the filter.