| 摘要 |
PURPOSE:To improve durability, the dispersibility etc. of magnetic powder by using a binder contg. a modified polyurethane resin contg. polyurethane molecules having OHs at other than both terminals of the main chain, a polyvinyl butyral resin and a specific urethane prepolymer. CONSTITUTION:The binder contg. a modified polyurethane resin contg. polyurethane molecules having 1-3 OHs at other than both terminals of the main chain and a polyvinyl butyral resin at compounding ratios 1:9-9:1 by weight and containing a urethane prepolymer of <=10,000mol.wts. of which both terminals of the main chain are NCO at 5-50wt% of the total amount of this and said two resins is prepd. Thereby, the dispersibility of magnetic powder is improved and a magnetic tape of high durability is obtained. Further, heat resistance, chemical resistance, etc. are much improved by adding a suitable amount of polyisocyanate of low mol. wt. |
