Nonmagnetic hematite powder for a magnetic recording medium and method of manufacturing the same

摘要

A nonmagnetic powder, used for the nonmagnetic layer of a coated type magnetic recording medium having a multilayer structure, has good dispersibility in the binder in which it is dispersed to prepare a coating material that is applied to the nonmagnetic layer. The nonmagnetic powder has an iron compound as its principal component and exhibits a maximum pore volume value in a pore diameter range of 0.01 µm to 0.05 µm within a pore diameter range of 0.0018 µm to 0.1 µm in which the relationship between pore diameter and pore volume is calculated by a mercury injection method. The nonmagnetic powder exhibits a cumulative pore volume value in a pore diameter range of 0.0018 µm to 0.01 µm that is not more than 30% of the cumulative pore volume value in the pore diameter range of 0.0018 µm to 0.1 µm.