To obtain excellent corrosion resistance by controlling a magnetic record medium in such a manner that when the medium is immersed in specified weight of purified water at a specified first temp. under normal pressure, then kept in the water at a specified second temp. for specified time, and then naturally cooled to the first temp., the soln. at the first temp. is in a specified range of pH.
This magnetic record medium consists of a supporting body 1 and a metal magnetic layer 2, and if necessary, a back layer 3, a protective layer 4 and a lubricant layer 5 are formed. This magnetic recording medium shows such property that when 5 g of the medium is immersed in 100 g of purified water under 1 atom at 20°C, kept in the water at 100°C under 1 atom for 5 min, and then naturally cooled to 20°C under 1 atom, the soln. is in 7.2 to 8.4 pH range. To obtain 7.2 to 8.4 pH range of the soln., for example, the content of oxygen or carbon in the metal magnetic layer 2 is controlled to 20 to 35 at.% or the nitrogen content is controlled to 10 to 35 at.%. Thereby, the obtd. medium has excellent corrosion resistance and does not give bad influences on a magnetic head.
KITAORI NORIYUKI
SASAKI KATSUMI
YOSHIDA OSAMU
ENDO KATSUMI
MIYAMURA TAKESHI
