Acicular magnetic iron-based alloy particles and process for producing the same.

摘要

Acicular magnetic iron-based alloy particles, the surfaces of which are coated with a polymer formed from at least one silicone compound represented by formula (I): (R<1>HSiO)a(R<2>R<3>SiO)b(R<4>R<5>R<6>SiO1/2)c (I) (wherein R<1>, R<2>, R<3>, R<4>, R<5> and R<6> each represent a hydrogen atom or hydrocarbon group having 1 to 10 carbon atoms which may be substituted by at least one halogen atom, a and b are respectively 0 or integers of not less than 1, and c is 0 or 2 provided that when c is 0, the sum of a and b is an integer of not less than 3), and which have a coercive force of not less than 111 kA/m (1400 Oe), a saturation magnetization of not less than 100 Am<2>/kg (100 emu/g), a major axial diameter of not more than 0.25 mu m and a switching field distribution of not more than 0.38; are useful as magnetic particles for magnetic recording media.