Abstract: Provided is a novel piezoelectric element that has a generally long linear shape and has excellent flexibility and bend resistance. The piezoelectric element includes a core wire which is a resin wire having at least one layer of metal foil helically wound therearound, an organic piezoelectric layer that coats the core wire, and a conductor layer that coats the organic piezoelectric layer. The metal foil and the conductor layer each function as an electrode having the organic piezoelectric layer interposed therebetween. The at least one layer of metal foil is helically wound around the resin wire with gaps, and the ratio of the gap to the helical pitch of the metal foil is 0.4% to 50%.

Abstract: Provided is a novel piezoelectric element that has a generally long linear shape and has excellent flexibility and bend resistance. The piezoelectric element includes a core wire which is a resin wire having at least one layer of metal foil helically wound therearound, an organic piezoelectric layer that coats the core wire, and a conductor layer that coats the organic piezoelectric layer. The metal foil and the conductor layer each function as an electrode having the organic piezoelectric layer interposed therebetween. The at least one layer of metal foil is helically wound around the resin wire with gaps, and the ratio of the gap to the helical pitch of the metal foil is 0.4% to 50%.

Abstract: A piezoelectric wire of the present invention includes a conductive wire 11 and a polymer piezoelectric layer 12 that coats the conductive wire 11. The polymer piezoelectric layer 12 contains a ?-phase polyvinylidene fluoride-based copolymer, and the conductive wire 11 has a wire diameter of 1.0 mm or less. The ?-phase polyvinylidene fluoride-based copolymer is preferably at least one selected from a vinylidene fluoride-trifluoroethylene copolymer and a vinylidene fluoride-tetrafluoroethylene copolymer.

Abstract: An object of the present invention is to provide a polarized vinylidene fluoride/tetrafluoroethylene copolymer resin film that can significantly reduce, when used as an optical film, the deterioration of the quality of video or still images formed by display elements. The present invention provides a polarized vinylidene fluoride/tetrafluoroethylene copolymer resin film having 2,000 or fewer spot defects per m2, the number of spot defects being measured by a defect measurement method; the method using an surface inspection system in which a CCD camera is placed so as to detect defects at an angle of 45 degrees relative to an LED source, defects of the film are read within a rectangular range of 300 mm in a width direction (the direction perpendicular to the scanning direction), and 150 mm in a machine direction (the scanning direction), while the film is scanned under the camera at a rate of 20 m/min; wherein first, defects having a bright area of 1.5 mm2 or less and a dark area of 1.

Abstract: An object of the present invention is to provide a polarized vinylidene fluoride/tetrafluoroethylene copolymer resin film that can significantly reduce, when used as an optical film, the deterioration of the quality of video or still images formed by display elements. The present invention provides a polarized vinylidene fluoride/tetrafluoroethylene copolymer resin film having 2,000 or fewer spot defects per m2, the number of spot defects being measured by a defect measurement method; the method using an surface inspection system in which a CCD camera is placed so as to detect defects at an angle of 45 degrees relative to an LED source, defects of the film are read within a rectangular range of 300 mm in a width direction (the direction perpendicular to the scanning direction), and 150 mm in a machine direction (the scanning direction), while the film is scanned under the camera at a rate of 20 m/min; wherein first, defects having a bright area of 1.5 mm2 or less and a dark area of 1.

Abstract: An object of the present invention is to provide a polarized vinylidene fluoride/tetrafluoroethylene copolymer resin film that can significantly reduce, when used as an optical film, the deterioration of the quality of video or still images formed by display elements. The present invention provides a polarized vinylidene fluoride/tetrafluoroethylene copolymer resin film having 2,000 or fewer spot defects per m2, the number of spot defects being measured by a defect measurement method; the method using an surface inspection system in which a CCD camera is placed so as to detect defects at an angle of 45 degrees relative to an LED source, defects of the film are read within a rectangular range of 300 mm in a width direction (the direction perpendicular to the scanning direction), and 150 mm in a machine direction (the scanning direction), while the film is scanned under the camera at a rate of 20 m/min; wherein first, defects having a bright area of 1.5 mm2 or less and a dark area of 1.

Abstract: An object of the present invention is to provide a polarized vinylidene fluoride/tetrafluoroethylene copolymer resin film that can significantly reduce, when used as an optical film, the deterioration of the quality of video or still images formed by display elements. The present invention provides a polarized vinylidene fluoride/tetrafluoroethylene copolymer resin film having 2,000 or fewer spot defects per m2, the number of spot defects being measured by a defect measurement method; the method using an surface inspection system in which a CCD camera is placed so as to detect defects at an angle of 45 degrees relative to an LED source, defects of the film are read within a rectangular range of 300 mm in a width direction (the direction perpendicular to the scanning direction), and 150 mm in a machine direction (the scanning direction), while the film is scanned under the camera at a rate of 20 m/min; wherein first, defects having a bright area of 1.5 mm2 or less and a dark area of 1.

Abstract: An electret is produced using a heat resistant electret material containing a fluorocarbon resin, in which a modified polytetrafluoroethylene is used as the fluorocarbon resin. Also, an electret including a metal member and a resin film adhered to a surface of the metal member is produced, in which the resin film contains polytetrafluoroethylene and only a surface on the metal member side of the resin film has been subjected to an adhesion-improving treatment. Thus, it is possible to provide a heat resistant electret exhibiting excellent charge retention ability at high temperatures.