| 摘要 |
PROBLEM TO BE SOLVED: To obtain an excellent surface characteristic and highdensity recording characteristic by applying specific nonmagnetic powder and binder on a nonmagnetic base to form a lower nonmagnetic layer and applying specific ferromagnetic metallic powder thereon to form an upper magnetic layer. SOLUTION: A coating liquid contg. nonmagnetic powder and a binder and further, a crosslinking agent of >=30wt.% of the binder is applied on the flexible nonmagnetic base to form the lower nonmagnetic layer. The lower nonmagnetic layer is formed to 0.1 to 4.0μm, more preferably 0.3 to 2.0μm thickness. Inorg. materials, such as metallic oxide, metal carbonate and metal sulfate are used for the nonmagnetic powder. Further, the coating liquid prepd. by adding ferromagnetic material powder, binder and assistant to a solvent is applied on the lower nonmagnetic layer to form the upper magnetic layer. The upper magnetic layer is preferably formed to <=0.5μm thickness. If the thickness is larger than this range, the magnetic layer is no longer suitable for high-density recording in terms of self-degaussing loss and thickness loss. TheσS of the ferromagnetic material powder is specified to >=l20Oemu, the coercive force thereof to >=1600Oe and the specific surface area thereof to >=40m<2> /g. As a result, the excellent surface characteristic is obtd. and smooth rotation is obtd.
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