Electroacoustic conversion film and electroacoustic converter
Provided are an electroacoustic conversion film and an electroacoustic converter which are capable of suppressing a decrease in piezoelectric conversion efficiency in a case of use in a high-temperature environment. The electroacoustic conversion film is an electroacoustic conversion film including a polymer-based piezoelectric composite material which contains piezoelectric particles in a matrix containing a polymer material, and electrode layers which are formed on both surfaces of the polymer-based piezoelectric composite material, in which the electroacoustic conversion film has a thermal expansion coefficient of 12 ppm/° C. to 100 ppm/° C.
1. An electroacoustic conversion film comprising:
a polymer-based piezoelectric composite material which contains piezoelectric particles in a matrix containing a polymer material; and
electrode layers which are formed on both surfaces of the polymer-based piezoelectric composite material,
wherein the electroacoustic conversion film has a thermal expansion coefficient of 12 ppm/° C. to 100 ppm/° C.,
wherein the electroacoustic conversion film has a hygric expansion coefficient in a range of 1 to 30 ppm/% RH at 25° C. and in a range of 3 to 40 ppm/% RH at 60° C.
2. The electroacoustic conversion film according to claim 1 , further comprising:
a protective layer laminated on a surface of the electrode layer on a side opposite to a surface provided with the polymer-based piezoelectric composite material.
3. The electroacoustic conversion film according to claim 1 ,
wherein the polymer-based piezoelectric composite material is polarized in a thickness direction.
4. The electroacoustic conversion film according to claim 1 ,
wherein the polymer-based piezoelectric composite material does not have in-plane anisotropy as a piezoelectric characteristic.
5. The electroacoustic conversion film according to claim 1 ,
wherein the polymer material has viscoelasticity at room temperature.
6. The electroacoustic conversion film according to claim 2 ,
wherein the polymer-based piezoelectric composite material is polarized in a thickness direction.
7. The electroacoustic conversion film according to claim 2 ,
wherein the polymer-based piezoelectric composite material does not have in-plane anisotropy as a piezoelectric characteristic.
8. The electroacoustic conversion film according to claim 2 ,
wherein the polymer material has viscoelasticity at room temperature.
9. The electroacoustic conversion film according to claim 3 ,
wherein the polymer-based piezoelectric composite material does not have in-plane anisotropy as a piezoelectric characteristic.
10. The electroacoustic conversion film according to claim 3 ,
wherein the polymer material has viscoelasticity at room temperature.
11. An electroacoustic converter comprising:
an electroacoustic conversion film which includes a polymer-based piezoelectric composite material containing piezoelectric particles in a matrix containing a polymer material and electrode layers which are formed on both surfaces of the polymer-based piezoelectric composite material; and
a vibration plate which is laminated on the electroacoustic conversion film,
wherein the electroacoustic converter has a thermal expansion coefficient of 12 ppm/° C. to 100 ppm/° C.,
wherein the electroacoustic conversion film has a hygric expansion coefficient in a range of 1 to 30 ppm/% RH at 25° C. and in a range of 3 to 40 ppm/% RH at 60° C.
12. The electroacoustic converter according to claim 11 ,
wherein an absolute value of a difference between a thermal expansion coefficient of the electroacoustic conversion film and a thermal expansion coefficient of the vibration plate is in a range of 0 ppm/° C. to 80 ppm/° C.
13. The electroacoustic converter according to claim 11 ,
wherein the electroacoustic conversion film has a thermal expansion coefficient of 12 ppm/° C. to 100 ppm/° C.
14. The electroacoustic converter according to claim 11 ,
wherein a loss tangent (Tan δ) of the electroacoustic conversion film at a frequency of 1 Hz and 60° C. according to dynamic viscoelasticity measurement is 0.03 or greater.
15. The electroacoustic converter according to claim 11 ,
wherein the electroacoustic conversion film includes a protective layer laminated on a surface of the electrode layer on a side opposite to a surface provided with the polymer-based piezoelectric composite material.
16. The electroacoustic converter according to claim 12 ,
wherein the electroacoustic conversion film has a thermal expansion coefficient of 12 ppm/° C. to 100 ppm/° C.
17. The electroacoustic converter according to claim 12 ,
wherein a loss tangent (Tan δ) of the electroacoustic conversion film at a frequency of 1 Hz and 60° C. according to dynamic viscoelasticity measurement is 0.03 or greater.
18. The electroacoustic converter according to claim 12 ,
wherein the electroacoustic conversion film includes a protective layer laminated on a surface of the electrode layer on a side opposite to a surface provided with the polymer-based piezoelectric composite material.
19. The electroacoustic converter according to claim 13 ,
wherein a loss tangent (Tan δ) of the electroacoustic conversion film at a frequency of 1 Hz and 60° C. according to dynamic viscoelasticity measurement is 0.03 or greater.
20. The electroacoustic converter according to claim 13 ,
wherein the electroacoustic conversion film includes a protective layer laminated on a surface of the electrode layer on a side opposite to a surface provided with the polymer-based piezoelectric composite material.