| 摘要 |
Provided is a magnetic recording medium that exhibits excellent electromagnetic characteristics especially in recording and reproducing systems using an MR head, as well as has excellent long-term preservation property. The magnetic recording medium comprises a lower layer comprising a nonmagnetic powder or a ferromagnetic powder and a binder and at least one magnetic layer thereover comprising a ferromagnetic powder and a binder on a support. Said binder comprised in the lower layer and/or magnetic layer comprises a polyurethane, said polyurethane is polyurethane (1) prepared from a chain extending agent, an organic diisocyanate, and a polyester polyol which comprises a dibasic acid component and a diol component, wherein the dibasic acid component comprises an aliphatic dibasic acid component and 70 molar percent or more of the diol component is derived from a diol having an alkyl branched side chain comprising two or more carbon atoms without a ring structure, or said polyurethane is polyurethane (2) prepared from a chain extending agent which comprises an alkyl branched aliphatic diol comprising three or more of total carbon atoms in a branched side chain per molecule, an organic diisocyanate, and a polyester polyol which comprises a dibasic acid component and a diol component, wherein the dibasic acid component comprises an aliphatic dibasic acid component and 70 molar percent or more of the diol component is derived from an alkyl branched aliphatic diol having a branched side chain of which total carbon atoms per molecule is two or more, and magnitude of saturation magnetic flux density (phim) ranges from 150 to 400 G.mum.
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