OXY IRON HYDROXIDE POWDER FOR MULTI-LAYERED MAGNETIC RECORDING MEDIUM, AND MAGNETIC RECORDING MEDIU

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PROBLEM TO BE SOLVED : To provide non-magnetic powder which can significantly improve the coated film strength while maintaining the smooth surface of the non-magnetic layer (lower layer) in a multi-layered magnetic recording medium. SOLUTION : This oxy iron hydroxide powder for a multi-coated magnetic recording medium has 7.5×1018/m2 or more of surface functional groups. Particularly, a preferable example is the powder having rare earth elements (Sc, Y can be treated as rare earth elements)on the particle surfaces, such as having an average long axis length of 10-200 nm when measured in the image photographed by using transmission electron microscope and a specific surface area of 30-200 m2/g by the BET method. The oxy iron hydroxide powder can be obtained by a surface treatment to cover the particle surfaces with rare earth elements (Sc, Y can be treated as rare earth elements). COPYRIGHT : (C)2008, JPO&INPIT