Polymer piezoelectric film
AssigneeKureha Kagaku Kogyo Kabushiki Kaisha
InventorsTeruo Sakagami, Kenichi Nakamura, Naohiro Murayama
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Abstract
A polymer piezoelectric film comprising a poled film of a vinylidene fluoride copolymer having a high molecular weight as defined by an inherent viscosity within a specific range comprising 40 to 90 mol. % of vinylidene fluoride and 10 to 60 mol. % of trifluoroethylene. Such a high molecular weight vinylidene fluoride copolymer can give a preferable state of molecular arrangement during film formation, particularly preferably formation by casting, to provide a film excellent in piezoelectric characteristic and secondary processing characteristic.
Claims7
A polymer piezoelectric film, comprising a cast and poled film of a vinylidene fluoride copolymer said copolymer being in a form and having a molecular weight to provide a solution suitable for forming into a film by the casting method and comprising 40 to 90 mol. % of vinylidene fluoride and 10 to 60 mol. % of trifluoroethylene and having an inherent viscosity of 3.0 dl/g or more as measured in a dimethylformamide solution at a concentration of 0.4 g/dl at 30.degree. C. and said film having an electromechanical coupling factor k.sub.t of 0.22 or greater.
Dependencies are inferred from the claim text.