| 摘要 |
PROBLEM TO BE SOLVED: To enable high density recording by incorporating a specific quantity of a silicone based surfactant in an upper layer magnetic layer having a specific thickness to improve the electromagnetic conversion characteristic of a multi- layer coating type magnetic recording medium. SOLUTION: The electromagnetic conversion characteristics such as the output, the overwrite or the like in short wave are improved by applying a magnetic layer formed by dispersing a ferromagnetic powder in a binder in a state that a non-magnetic layer is undried so as to be <=0.5μm thick after the calender treatment to reduce the recording demagnetization. At this time, 0.1-1.5 pts.wt. silicone based surfactant expressed by a formula is incorporated to 100 pts.wt. coating material for forming the magnetic layer. In the formula, each of (m), (n), (m'), (n'), (a) and (b) is an independent integer of 1-10 and R represents an alkyl group or an allyl group. As a result, an organic solvent is vaporized without damaging surface smoothness by suppressing the over convection in drying to lower the surface tension and the electromagnetic conversion characteristic is improved by securing the smoothness.
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