| 摘要 |
PURPOSE:To improve the surface properties of a magnetic layer and the electromagnetic conversion characteristics, by using a binder contg. polyurethane resin and a vinyl chloride-vinyl acetate copolymer contg. maleic acid. CONSTITUTION:Polyurethane resin to be used is an addition polymer consisting of polyester polyol and 2,4-tolylene diisocyanate and having <=150 deg.C softening temp., 10,000-200,000 average mol.wt. and about 200-2,000 polymn. degree. A binder is prepared using the polyurethane resin and a vinyl chloride-vinyl acetate copolymer contg. maleic acid as principal components. The binder contg. both the components improves the surface properties of fine-grained iron oxide by the synergistic effect of the three-dimensional effect of tolyelene diisocyanate with the effect of maleic acid adsorbing on iron oxide. |
