| 摘要 |
PURPOSE:To obtain a magnetic recording medium contg. well dispersed magnetic powder and having superior surface smoothness, durability and heat resistance by forming a magnetic layer contg. specified thermoplastic polyurethane resin, a specified ester compd. and ferromagnetic fine powder surface-treated with a specified coupling agent and a specified phosphoric ester. CONSTITUTION:Thermoplastic polyurethane resin having specified mol.wt., tensile rupture strength, tensile rupture elongation, 100% modulus and glass transition point, a specified ester compd. represented by formula I and magnetic powder surface-treated with a specified phosphoric ester such as a compd. represented by formula II and a specified coupling agent are used. In the formula I, each of R1 and R2 is 1-25C straight chain or branched satd. alkyl group and R3 is 7-29C straight chain or branched (un)satd. alkyl group. In the formula II, R is 2-28C hydrocarbon or acyl group A is 2-24C alkylene group, (n) is 0 or an integer of 1-30 and (l) is 1, 1.5 or 2. The components are easily converted into a magnetic coating material having superior dispersibility and stability. When the coating material is applied, a magnetic layer having superior smoothness is formed.
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