MAGNETIC IRON OXIDE POWDER FOR TRANSPARENT MAGNETIC RECORDING LAYER, ITS MANUFACTURING METHOD,A ND MAGNETIC RECORDING MEDIUM HAVING TRANSPARENT MAGNETIC RECORDING LAYER USING THIS MAGNETIC IRON OXIDE POWDER

摘要

PURPOSE: To provide a magnetic recording medium including a transparent magnetic recording layer having good magnetic characteristics and light transmissivity with small dependency on wavelength. ;CONSTITUTION: At 40 to 100C, a tin-chloride solution is added to a water dispersion solution of ph8 to 10 while the same potential of hydrogen is kept. In this case the dispersion solution contains magnetic powder of iron oxide particles. Then, a surface of the particle is coated with tin oxide or tin hydroxide to obtain magnetic powder of iron-oxide particles for a transparent magnetic recording layer. In a magnetic recording medium, a transparent magnetic recording layer is made up of bonding resin of 100 parts by weight and magnetic powder of iron-oxide particles of 0.1 to 100 parts, with saturation magnetic flux (Bm) of 3 to 600G, and transmissivity (T400) of 25 to 98% for light wavelength of 400nm. In addition, a ratio of transmissivity of light wavelength of 400nm to light wavelength of 700nm ranges from 0.70 to 0.98.;COPYRIGHT: (C)1996,JPO