| 摘要 |
PURPOSE:To obtain a disk which has high dimensional stability even at and under a high temp. and humidity and is free from a tracking miss by adjusting the coeffts. of temp. and humidity expansion of a biaxially oriented film consisting of specific polyester and polyethylene terephthalate at a specific compounding ratio. CONSTITUTION:A biaxially oriented film consists of 95-70wt% chain polyester in which >=90mol% of a glycol component is 1,4-cyclohexane dimethanol and >=80mol% of the dibasic component consists of terephthalic acid and 5-30wt% polyethylene terephthalate. A magnetic layer is formed on a base material consisting of such film of which the max. coefft. of temp. expansion on the plane inclusive of the longitudinal and transverse directions thereof is 10-35(X10<-6>/ deg.C), the max. coefft. of humidity expansion is 3-8.0(X10<-6>/RH), the difference between the max. and min. coefft. of temp. expansion is 0-6.0(X10<-6>/ deg.C) and the difference between the max. and min. coefft. of humidity expansion is 0-4.0(X 10<-6>/RH). The flexible disk which has good dimensional stability at low - high temp., has substantial strength and is free from a tracking miss is thus obtd. |
