magnetic recording medium

Abstract

Abstract PURPOSE:To obtain the magnetic recording medium which has good adhesive strength and decreases drop-outs by using a specific carbon black in a back coat layer and compounding a prescribed amt. of ammonium sulfate. CONSTITUTION:The back coat layer is formed to contain the carbon black having 6.0 to 12.0 pH and ammonium sulfate and the compounding ratio of the ammonia sulfate is specified to 0.5 to 5.0pts.wt. per 100pts.wt. compounding ratio of the carbon black. The adhesive strength of the back coat layer to a nonmagnetic material degrades if the pH is below 6.0. The reaction in a coating compd. is too fast and the thickening and gelatinizing are resulted when a hardener is compounded if the pH exceeds 12. The desired surface roughness of the back coat layer is then not obtainable. The effect of decreasing the drop-outs is lost if the compounding ratio of the ammonia sulfate is below 0.5pt.wt. per 100pts.wt. carbon black. The coating material thickens and the dispersion is difficult if the compounding ratio exceeds 5.0pts.wt. The chipping at the time of traveling is obviated in this way and the excellent adhesiveness is obtd. In addition, the drop-outs are decreased.

Inventors

• 👤 Nobuyuki Oshima
• 👤 尾島　信行

Bibliographic Details