MAGNETIC RECORDING MEDIUM

摘要

PURPOSE:To maintain substantial wear resistance for a long period of time by forming a protective layer contg. pulverous nonmagnetic porous particles, lubricating agent and binder on the surface of a nonmagnetic base sheet on the side opposite from the surface on which a magnetic layer is formed. CONSTITUTION:A dispersion is first produced by kneading preliminarily and thoroughly channel black and perchloropolyalkyl ether in a ball mill and dispersing and mixing the kneaded mixture together with a fluororesin and solvent in a sand mill. Isocyanate is added to such dispersion and is thoroughly dissolved with a stirrer to prepare a coating liquid. Such coating liquid is coated on the rear surface of a stock sheet for a magnetic tape consisting of a polyethylene telephthalate film base and is dried in a hot wind drying furnace kept at 100 deg.C and is further rested overnight in a thermostatic chamber kept at 60 deg.C by which the sheet is subjected to a curing treatment. The film thickness of the resulted protective layer for the rear surface is 0.2mum. Such stock sheet for the tape is slit to 12.65mm width and the coefft. of dynamic friction of the rear surface of the resulted tape sample with a stainless steel bar is measured and the value as small as 0.2 is obtd.