| 简介 |
PROBLEM TO BE SOLVED : To make surely discriminable a magnetic recording medium from other magnetic recording media and prevent an unauthorized action by making the magnetic recording medium include a magnetic material composed of a hard magnetic substance (A), a hard magnetic substance (B) of a smaller coercive force than the hard magnetic substance (A) and a soft magnetic substance (C), in a predetermined dense-and-thin pattern into a second magnetic layer. SOLUTION : A base material 2 is formed of polyester such as PET, PET-G, PEN or the like, vinyl chloride, or the like. A first magnetic layer 3a uses magnetic fine particles such as γ-Fe2O3, Co applied γ-Fe2O3, Fe3O4, CrO2 or the like including a magnetic material of a coercive force in the range of 300-6000 (e). A second magnetic layer 3b contains three kinds of magnetic materials in a predetermined dense-and-thin pattern. A hard magnetic material A is Ba ferrite, Sr ferrite or a rare earth-based material for forming permanent magnets which has a coercive force of 6, 000 (e) or larger, a hard magnetic material B is γ-Fe2O3, Co-applied γ-Fe2O3 or the like having a coercive force in the range of 100-5, 000 (e), and a soft magnetic material C is Al, Si, Fe or the like having a coercive force of 200 (e) or smaller. |
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