Piezoelectric and pyroelectric film and method for preparing the film
First Claim
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1. A method for preparing a piezoelectric and pyroelectric film comprising the steps of,biaxially stretching a film made from a resincomposition 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°
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
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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 3×10-3 and a ratio of d31 /d32 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° C. before or at the same time of a treatment for orientation polarization of the film.
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Citations
8 Claims
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1. 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°
C. and is higher than the secondary transition temperature of said resin composition; andat the same time or after the additional stretching polarizing the thus additionally stretched film - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification