Magnetic recording medium comprising a magnetic film layer and a coating of purified perfluoropolyther lubricant

A magnetic recording medium comprising a magnetic film layer having coated thereon a layer of purified perfluoropolyether lubricant having the formula:

• Piperonyl--OCH.sub.2 CF.sub.2 O--(CF.sub.2 CF.sub.2 O).sub.n --(CF.sub.2 O).sub.m --CF.sub.2 CH.sub.2 O--Piperonyl
• which lubricant has a weight-average molecular weight of at least 2000 and a weight-average molecular weight/number average molecular weight ratio of not more than 1.3 and which contains no chemical species having a molecular weight of less than about 700, and wherein said lubricant has been purified by
• 1) dissolving said lubricant in a good solvent to obtain a uniform solution,
• 2) adding to the solution of lubricant in good solvent a poor solvent under stirring in an amount of from 4-5 times the amount of good solvent already present,
• 3) thoroughly mixing the solution obtained in (2),
• 4) allowing the mixed solution obtained in (3) to stand still and phase separate,
• 5) collecting the good solvent containing the lubricant,
• 6) repeating steps (2)-(4) at least three times,
• 7) removing the good solvent from the lubricant,
• 8) filtering the lubricant.