| 摘要 |
PURPOSE:To obtain the titled recording medium having high S/N and suitable for high-density recording by incorporating granular alpha-Fe2O3 having about 0.05-1mum mean particle size and carbon black in to a magnetic layer. CONSTITUTION:Granular alpha-Fe2O3 (having about 0.05-1mum mean particle size) and carbon black are used as an additive in a magnetic layer. For example, the mixture of 100pts.wt. Co-contg. gamma-Fe2O3 having about 28-30m<2>/g specific surface, 10pts.wt. vinyl chloride-vinyl acetate copolymer, 10pts.wt. polyurethane resin, 10pts.wt. granular alpha-Fe2O3 having about 0.3mum mean particle size, 8pts.wt. carbon black having 120 staining power and 230pts.wt. mixed solvent contg. the same amt. of methyl ethyl ketone, toluene and methyl isobutyl ketone is mixed and dispersed in a sand mill to form a magnetic paint. An isocyanate curing agent is added to the magnetic paint and uniformly mixed and the mixture is coated on a tape to make a magnetic tape.
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