| 摘要 |
PURPOSE: To obtain a magnetic recording medium suitable for use in the open air by using a substrate film made of arom. polyamide and preventing the deterioration of prescribed performance. CONSTITUTION: A magnetic layer is formed on at least one side of an arom. polyamide film contg. >=50mol% bonded units represented by formulae I, II. The product of the coefft. of thermal expansion of the film and the hygroscopic rate is <=3×10<-5> and residue on extraction is <=0.5% when the film is subjected to extraction with methylene chloride. In the formulae I, II each of Ar1 , Ar2 and Ar3 is a para-bonding type arom., each of R, R' and R" is a functional group selected from among halogen, nitro, cyano, 1-4C alkyl, 1-3C alkoxy and trialkylsilyl, 1+m>1 and m>0.5. The objective magnetic recording medium suitable for use in the open air is obtd. without deteriorating superior dynamic performance peculiar to the arom. polyamide.
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