Method for manufacturing polymeric piezoelectric film and polymeric piezoelectric film

Abstract

A method for producing a polymer piezoelectric film, comprising: a process of moving and stretching a crystalline polar polymer sheet in contact with a conductive stretching roller having a diameter of at least 30 mm and a surface friction coefficient which has been reduced to such a level as to allow a relative displacement of the crystalline polar polymer sheet in contact with the conductive stretching roller: and a step in the process of applying a polarization voltage between an electrode disposed opposite to the crystalline polar polymer sheet and the conductive stretching roller to polarize the crystalline polar polymer sheet. As a result, it is possible to stably produce a polymer piezoelectric film exhibiting stable piezoelectricity over a large area. Especially, it is possible to obtain polymer piezoelectric film exhibiting a temperature-dispersion peak temperature of d 31 piezoelectricity coefficient at at least 120° C. and surface scratches extending in one direction.

1 - 10 . (canceled) 
     
     
         11 . A polymer piezoelectric film, exhibiting a temperature-dispersion peak temperature of d 31  piezoelectricity coefficient at at least 120° C., and surface scratches extending in one direction. 
     
     
         12 . The polymer piezoelectric film according to  claim 11 , exhibiting the temperature-dispersion peak temperature of d 31  piezoelectricity coefficient at at least 120° C. over an area thereof covering a full width in a direction perpendicular to a direction of developing the d 31  piezoelectricity coefficient and a length of at least 1 m in the direction of developing the d 31  piezoelectricity coefficient. 
     
     
         13 . The polymer piezoelectric film according to  claim 11 , exhibiting a d 31  piezoelectricity coefficient distribution giving an average of 15-35 pC/N and a local deviation thereof within ±20% or less from the average. 
     
     
         14 . The polymer piezoelectric film according to  claim 11 , comprising a polyvinylidene fluoride resin.