| 摘要 |
<p>PURPOSE:To improve productivity by using a fine pore-contg. polyester film having an apparent density and hiding degree of specific values as a substrate and forming a magnetic layer on one face. CONSTITUTION:The polyester film contg. the fine pores on the surface and in the inside is used. The apparent density of the film is specified to >=0.4g/cm<3> and <=1.3g/cm<3> and the hiding degree thereof to >=0.2. A magnetic powder material is finely dispersed therein to form a thin film layer, by which the coating type magnetic layer is obtd. The quantity of the fine pores decreases and the resilience is lost if the apparent density exceeds 1.3g/cm<3>. The mechanical strength is insufficient if said density is below 0.4g/cm<3>. The size of the closed cells increases and the degraded mechanical strength and the roughened surface are resulted if the hiding degree is <0.2. Problems arise in the adhesiveness to the magnetic layer and the sharpness of various kinds of printing in such a case.</p> |
