| 摘要 |
PURPOSE:To provide a magnetic recording medium having a magnetic layer with low light transmittance by applying a magnetic coating material contg. a deriv. of a benzopyrylium salt or a benzothiapyrylium salt by 1-10wt% of the amount of a magnetic body to a nonmagnetic support to form the magnetic layer. CONSTITUTION:A deriv. of a benzopyrylium salt or a benzothiapyrylium salt used in this invention is represented by formula I (where R<1> is H or phenyl, R<2> is p-methoxyphenyl or 4-methoxynaphthyl, X is O or S, and Y is an anionic functional group). When the deriv. is incorporated into a magnetic layer, the transmittance of the layer to light of 800mmu wavelength is reduced, and the electrification of the layer is also reduced because the deriv. has the function of dye sensitization. The preferred amount of the deriv. is 1-10wt% of the amount of a magnetic body. The effective magnetic body is Co-contg. gamma-hematite having 30-50m<2>/g B.E.T. specific surface area. |
