PRODUCTION OF MAGNETIC RECORDING MEDIUM

PURPOSE:To obtain a porous magnetic coated film which is microporous and is uniformly dispersed with micropores by coating a magnetic coating compd. added with polyalkylene oxide on a substrate to form a coated film thereon, then curing the binder by a heat treatment to thermally decompose and evaporate the polyalkylene oxide. CONSTITUTION:The polyalkylene oxide which is the additive is quickly oxidized and decomposed in an about 180-230 deg.C range. Said additive exhibits good compatibility to the binder of the magnetic coating compd. While said additive can be added to the compd. in a wide range of concn., the size of the pores increases and the large pores are the cause for noise generation if the amt. of said additive to be added is too large. The micropores of the amt. sufficient for impregnation of a lubricating agent are not obtainable if the amt. is too small. The adequate amt. at which the above-mentioned additive is used is in the range of 1-30wt.% of the binder of the magnetic coating compd. The many micropores which are not obtainable heretofore are formed by forming the coated film and subjecting the film to a suitable heat treatment, by which the magnetic coated film impregnated with the lubricating agent in a large amt. is obtd.