| 摘要 |
PURPOSE:To enable simultaneous improvement of durability and electromagnetic conversion characteristic by using the polyisocyanate limited to a specific range in the total content of a binder for a magnetic layer as said binder and incorporating one kind of fatty acid at a specific rate or above into ferromagnetic fine particles as a lubricant. CONSTITUTION:A magnetic layer of a magnetic recording medium formed by coating a magnetic layer contg. ferromagnetic fine particles on a nonmagnetic base contains a vinyl chloride/vinyl acetate copolymer contg. a carboxylic group, polyurethane and polyisocyanate as a binde which are used at 20-50wt% by the total weight of the binder. At least one kind of a fatty acid, fatty acid ester, fatty acid modified silicone and alpha-olefin oxide are incorporated as a lubricant in the ferromagnetic fine particles in >=10wt% per the weight of said particles. Such particles are used for a magnetic disc and magnetic sheet, by which generation of various defects predicted when >=10wt% lubricant is used with the magnetic tape is obviated and durability and the surface characteristic of the magnetic layer, i.e., electromagnetic conversion characteristic are simultaneously improved. |
