Piezoelectric and pyroelectric film and method for preparing the film
AssigneeKureha Kagaku Kogyo Kabushiki Kaisha
InventorsTohru Sasaki, Syuuzi Terasaki, Tomoo Susa
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Abstract
A piezoelectric and pyroelectric film made from a resin composition of polymer of vinylidene fluoride, which is characterized by an index of birefringence of larger than 3.times.10.sup.-3 and a ratio of d.sub.31 /d.sub.32 of 0.3 to 3.0, and which may be prepared by further stretching a biaxially stretched film made from the above-mentioned resin composition at a temperature lower than the temperature of the biaxially stretching by more than 20.degree. C. before or at the same time of a treatment for orientation polarization of the film.
Claims8
A method for preparing a piezoelectric and pyroelectric film comprising the steps of,
- biaxially stretching a film made from a resin
- composition of a polymer of vinylidene fluoride;
- additionally stretching the thus obtained biaxially stretched film at a temperature of lower than the crystallizing temperature of said resin composition, which additional stretching temperature is lower than the temperature at the biaxially stretching by more than 20.degree. C. and is higher than the secondary transition temperature of said resin composition;
- and
- at the same time or after the additional stretching polarizing the thus additionally stretched film
Dependencies are inferred from the claim text.