Magnetic recording medium, non-magnetic acicular black iron-based composite particles and process for producing the particles

摘要

A magnetic recording medium composed of a non-magnetic base film; a non-magnetic undercoat layer formed on the non-magnetic base film, including a binder resin and non-magnetic acicular black iron-based composite particles; and a magnetic coating film comprising a binder resin and magnetic particles. The non-magnetic acicular black iron-based composite particles having an average major axis diameter of about 0.011 to 0.35 mum, and are composed of acicular hematite particles or acicular iron oxide hydroxide particles (as core particles) having an average major axis diameter of 0.01 to 0.3 mum; a coating layer formed on the surface of the core particles of a specific organosilicon compound; and a single carbon black coat formed on the coating layer in an amount of 21 to 50 parts by weight based on 100 parts by weight of the core particles.