MAGNETIC RECORDING MEDIUM AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To prevent a lubricant from being converted into a low molecular compd. and being decomposed, and to maintain stable lubricity over a long period even in an atmosphere of acidic gas in a hermetically sealed space. SOLUTION: In a 1st coating process, a medium obtd. by forming a protective layer 4 of carbon on a magnetic layer 3 is coated with a soln. prepd. by diluting a hydrocarbon lubricant such as fatty acid ester to 0.02wt.% concn. with dichloromethane as a solvent by a dipping method at 1mm/sec pulling rate. In a 2nd coating process, the medium is further coated with a soln. prepd. by diluting a perfluoro-polyether lubricant having a wt. average mol. wt. (Mw) of about 4,000 and hydroxyl groups as terminal groups to 0.05wt.% concn. with perfluorooctane as a solvent by a spin coating method at 1,800r.p.m. number of revolutions so that 16Åfilm thickness of the perfluoro-polyether is attained. The low mol. wt. hydrocarbon lubricant covers the surface of the medium and penetrates between molecules of the perfluoro-polyether, the adsorption of harmful acidic gas on the surface of the medium is not caused and the perfluoro-polyether is hardly decomposed to maintain stable lubricity over a long period.