| 摘要 |
PURPOSE:To obtain a high piezoelectric modulus, and to maintain piezoelectric properties even at a comparatively high temperature by orienting a copolymer film containing a specific quantity of a specified substance and polarizing and treating the film at a temperature of 50-140 deg.C. CONSTITUTION:A trifluoroethylene-vinylidene fluoride-vinyl fluoride three- element copolymer is acquired through a solution polymerization method or a block polymerization method in the presence of a normal radical catalyst from 15-60mol% trifluoroethylene, 30-80mol% vinylidene fluoride and 3-20mol% vinyl fluoride. A bringing to the outsides of the ranges of trifluoroethylene, vinylidene fluoride and vinyl fluoride is undesirable because a piezoelectric modulus is reduced or heat stability is deteriorated. The copolymer film is oriented, and polarized and treated, thus obtaining a piezoelectric material. There are a hot electret method, a corona discharge method, etc. as polarization treatment methods, but the film is polarized and treated at a temperature of 50-140 deg.C, thus acquiring the film having the high piezoelectric modulus.
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