| 摘要 |
PURPOSE: To improve S/N and durability by incorporating specific particulate nonmagnetic metal oxides, lubricants and a comb-shaped block copolymer as a dispersant at restricted ratios into particulate magnetic materials having a specified specific surface area. CONSTITUTION: This magnetic recording carrier contains at least one kind of the particulate nomnagnetic metal oxides having Mohs hardness larger than 5 and the specific surface area based on BET of at least 2m<2> /g at a ratio of 1 to 20wt.% of the weight of at least one kind of particulate magnetic materials having the specific surface area based on BET of at least 25m<2> /g, at least one kind of the lubricants selected from a group consisting of silicone resins, polyethylene wax and metal salts of paraffin, etc., at a ratio of 1 to 10wt.% and the comb-shaped block copolymer consisting of a polyethylene imine chain having a mol.wt. of at least 2000 as a base and having a polyamide and/or polyester side chain having a mol.wt. of at least 500 at a ratio of 1 to 20wt.%. As a result, the S/N and the resistivity to the wear of the layer surface are improved. |
