| 摘要 |
PURPOSE:To improve magnetic powder dispersibility, durability and surface smoothness by using a specific polyurethane resin as a binder. CONSTITUTION:The polyurethane resin having at least >=1 respectively among 3 kinds of polar groups; SO3M group, COOM group (M is H, Li, Na or K) and OH group in the molecular chain is used. A magnetic recording medium is produced by coating a magnetic paint for which the polyurethane resin is used as the binder and to which pulverous ferromagnetic powder and additive, etc. are added together with an org. solvent, on a non-magnetic substrate and drying the coating. The ratio of the binder and the pulverous ferromagnetic powder is 10-100pts.wt., more preferably 20-50pts.wt. by 100pts.wt. pulverous ferromagnetic powder. The mechanical strength and wear resistance are not enough if the ratio of the binder is below 10pts.wt. The magnetic powder density in the magnetic layer decreases and the satisfactory performance (reproduced output, etc.) as the magnetic recording medium is not obtainable if the ratio of the binder is increased to 100pts.wt. or above.
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