| 摘要 |
PURPOSE:To obtain a magnetic recording medium having a magnetic layer which is excellent in the dispersibility and dispersion stability of magnetic powder, has good surface smoothness and has an excellent electrical characteristics by incorporating high mol.wt. naphthalene sulfonic acid/formaldehyde condensate surface active agent in the magnetic layer. CONSTITUTION:Magnetic powder and high mol.wt. naphthalene sulfonic acid/ formaldehyde condensate surface active agent are incorporated in a magnetic layer. The high mol.wt. naphthalene sulfonic acid/formaldehyde condensate surface active agent is expressed by the formula and is used preferably in a range of 0.1-10wt% to the magnetic powder. The high mol.wt. naphthalane sulfonic acid/formaldehyde condensate surface active agent is soluble in water and when said agent contacts with the magnetic powder dispersed in an aq. soln., the agent sticks satisfactorily on the particle surfaces and forms a film, by which the dispersibility and dispersion stability of the magnetic powder are improved and the surface smoothness and electrical characteristics of the magnetic layer are improved. |
