US 12,004,429 B2
Piezoelectric body film, piezoelectric body film production method, and piezoelectric body device
Yusuke Sato, Tokyo (JP); Hisaaki Terashima, Tokyo (JP); Nobufumi Sato, Tokyo (JP); Kazuyuki Kanno, Tokyo (JP); and Keiko Aita, Tokyo (JP)
Assigned to KUREHA CORPORATION, Tokyo (JP)
Filed by Kureha Corporation, Tokyo (JP)
Filed on Sep. 11, 2023, as Appl. No. 18/464,745.
Application 18/464,745 is a division of application No. 16/969,605, previously published as PCT/JP2018/039056, filed on Oct. 19, 2018.
Claims priority of application No. 2018-038532 (JP), filed on Mar. 5, 2018.
Prior Publication US 2023/0422627 A1, Dec. 28, 2023
Int. Cl. H10N 30/098 (2023.01); B29C 71/02 (2006.01); C08J 5/18 (2006.01); H10N 30/857 (2023.01)
CPC H10N 30/857 (2023.02) [C08J 5/18 (2013.01); C08J 7/08 (2013.01); H10N 30/098 (2023.02); C08J 2327/16 (2013.01)] 3 Claims
 
1. A method of producing a piezoelectric body film, the method comprising:
forming a film, the forming including forming a crystalline polymer film having piezoelectricity by subjecting a sheet to stretching treatment and polarization treatment, the sheet being formed from a fluororesin containing a repeating unit derived from vinylidene fluoride as a main constituent unit;
performing relaxation including performing heat fixation and relaxation of residual strain of the crystalline polymer film by subjecting the crystalline polymer film to heating at a first temperature that is not lower than 90° C. and not higher than 115° C. for not less than 5 seconds and not more than 130 seconds; and
performing a secondary heating including subjecting the crystalline polymer film after the performing relaxation to reheating at a temperature that is not lower than the first temperature and not higher than 140° C. for not less than 15 seconds and not more than 120 seconds, and producing the piezoelectric body film.