| 摘要 |
PURPOSE:To obviate generation of a tracking error when under conditions of high temp. and high humidity by specifying the coefft. of expansion by temp. and humidity of a biaxially oriented film consisting of poly-1,4-cyclohexylenedimethylene terephthalate polyester. CONSTITUTION:The biaxially oriented film consisting of the poly-1,4-cyclohexylenedimethylene terephthalate polyester of which >=80mol% acid component is constituted of terephthalic acid is used as a base material. The coefft. of expansion by max. temp. on the surface including the longitudinal and transverse directions of such film is 9-35X10<-6> deg.C<-1>, the coefft. of expansion by the max. humidity is 0-8.0X10<-6> deg.C(%RH)<-1>, the difference between the coefft. of expansion by the max. and min. temp. is 0-8.0X10<-6> deg.C<-1> and the difference between the coefft. of humidity by the max. and min. humidity is 0-3.0X10<-6>(%RH)<-1>. A magnetic recording layer consisting of a thin metallic film is provided to such base material. A flexible disc for magnetic recording is obtd. on a biaxially oriented film of poly-1,4-cyclohexylenedimethylene terephthalate polyester by using a method such as vacuum deposition, sputtering, ion plating, CVD or electroless plating. |
