Sughrue, Mion, Zinn, Macpeak & Seas, PLLC
Biaxially oriented polyester film for a membrane switch
 A biaxially oriented polyester film for a membrane switch, which is made from a polyester containing at least 80 mol % of ethylene-2,6-naphthalene dicarboxylate recurring units and which has an endothermic peak with an endothermic energy of at least 0.4 mJ/mg at a temperature of 110 to 160.degree. C. This film is produced by subjecting a biaxially oriented polyester film produced from the above polyester in accordance with a method known per se to the following steps in the order named: PA1 (1) the step of heating the film under no strain at a temperature of 150 to 180.degree. C. for 1 to 5 hours; and PA1 (2) the step of heating the film in an unrolled or rolled state at a temperature of 80 to 122.degree. C. for 5 to 200 hours. 
Teijin Limited
C B H Y Y B B B C Y Y H
C08J B29C H01H Y10T Y10T B29C B29C B29K C08J Y10T Y10T H01H
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Kenji Shinichi Koji Shinya
Suzuki Kawai Furuya Watanabe