| 摘要 |
PROBLEM TO BE SOLVED: To provide a secondarily aggregated body of metallic magnetic grains, from which a magnetic coating film having enhanced surface smoothness and squareness ratio can be obtained when a coating type magnetic recording medium is produced because of its excellent kneading characteristics with various binder resins and organic solvents in a kneading machine and its excellent diluting and dispersing characteristics in the addition of an organic solvent, further which has high storing efficiency and transporting efficiency and moreover excellent in handling performance because of being provided with good fluidity as well. SOLUTION: In this secondarily aggregated body of metallic magnetic grains for magnetic recording, the average diameter of major axis of the primary grains of the metallic magnetic grains is 0.05 to 0.25 μm, and the average grain size of the secondarily aggregated body is 300 to 800 μm, the upper limit value of the grain size is 2,000 μm, and the angle of repose is 38 to 45 degrees, and the secondarily aggregated body is obtained by disintegrating the granulated material of metallic magnetic grains by a device having a function of disintegrating the same with a rotor and a grading function of forcedly passing the same through a screen. |
