| 摘要 |
PURPOSE:To decrease drop-out and to improve a signal to noise ratio and the running property of a back layer by using a back layer contg. carbon black having 0.1-1.0mu average primary particle size and polishing agent particles having >=6 Mohs' hardness and <=1mu average particle size. CONSTITUTION:The back layer of a magnetic recording medium provided with a magnetic layer on one side of a non-magnetic substrate and the back layer on the other side contains the carbon black having 0.1-1.0mu average primary particle size and the polishing agent particles having >=6 Mohs' hardness and <=1mu average particle size. The non-magnetic powder contains >=50wt% carbon black and the ratio of the non-magnetic powder and the total binder is 300/100-50/100, more particularly preferably 200/100-50/100. Chromium oxide, aluminum oxide, iron oxide, Mo2C, B4C, TiC, etc. are used for the polishing agent. A known thermoplastic resin, thermosetting resin or reaction type resin and the mixture composed thereof are used for the binder. |
