| 摘要 |
PURPOSE:To provide a magnetic powder layer having excellent anti-rust property, still stability and durability, by allowing polyamide resin having a reactive functional group and a hardening agent having a group capable of making reaction with the reactive functional group of the polyamide resin so as to harden the resin through bridge formation, in such a manner as to coat the surface of the magnetic powder layer by a film of the hardened polyamide resin. CONSTITUTION:Magnetic powder to which this art pertains may be oxide magnetic powders such as gamma-Fe2O3, metallic magnetic powders such as of Co-Ni-P alloy, and so forth. The polyamide resin having a reactive functional group preferably has a chemical composition as shown by the attached Figure. In this Figure, X<1>-X<3> represent substances which may be same or different. The substances X<1>-X<3> contain either one of hydrogen atom, hydroxy group, amino group, alkyl group, carboxyl group, alkenyl group, and allylic group. At least one of these substances X<1>-X<3> should contain a reactive functional group. Isocyanate compounds, epoxy compounds, acidic anhydride, lactone or the like can be used as the hardening agent having a group capable of making reaction with the reactive functional group of the polyamide resin. |
