| 摘要 |
PURPOSE:To alleviate agglomeration of CrO2 powder produced in vertical orientation processing, and to obtain practically sufficient surface smoothness and square ratio in the perpendicular direction by using CrO2 coated with CrO(OH) on the surface as a ferromagnetic fine powder. CONSTITUTION:A nonmagnetic base is coated with a magnetic coating material composed essentially of a binder and CrO2 powder having the surface coated with a CrO (OH) layer, and a DC magnetic field perpendicular to the coating film is applied between a pair of orienting magnets arranged in advance on both upper and lower sides of the base and the fine CrO2 is oriented in the direction perpendicular to the coating film before the coating film is dried and fluidity is lost, and drying is promoted by heating to form a magnetic layer. The intensity of the applied magnetic field is somewhat changed in accordance with the coating speed, coating viscosity, and the kinds of the ferromagnetic fine powder, and, an intensity of 1-4 kilogauss is preferable. Since the smaller thickness of the magnetic layer redness self-demagnetization, and enhances coercive force, a thickness of 1-5mum is suitable for high density recording. The coercive force of CrO2 of 500-1,000Oe is used and it is suitable for <= few mum shortwave length wave recording.
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