| 摘要 |
PURPOSE:To produce such a video tape having a small coefft. of dynamic friction, low deck tension of the tape and no damage of the tape after repeatedly run by providing a back coating layer the binder of which contains macromolecular copolymers into which negative functional groups are introduced as inner salts. CONSTITUTION:The magnetic recording medium consists of a supporting body, a magnetic layer on one side of the supporting body, and the back coating layer containing nonmagnetic powder and the binder on the other side of the supporting body. The binder in the back coating layer contains modified vinyl chloride copolymers and/or modified polyurethane copolymers into each of which negative functional groups are introduced as inner salts. As the back coating layer thus formed has a small coefft. of dynamic friction, the obtd. tape has low deck tension and little damage after repeatedly run. The back coating material has an excellent uniform dispersiveness and realizes a fine surface roughness of the back coating layer, so that the roughness of the back coating layer is not transferred to the magnetic layer. |
