| 摘要 |
<p>PROBLEM TO BE SOLVED: To maintain the excellent running durability and still durability and the running durability and storage stability under a high temperature and a high humidity by a method wherein binder contains polyurethane resin and, further, containes diester compound as lubricant. SOLUTION: A magnetic layer in which ferromagnetic fine powder and binder are dispersed is formed on a nonmagnetic supporter. The binder contains polyurethane resin containing polar groups and, further, contains diester compound expressed by the formula I as lubricant. In the formula I, R<1> and R<2> denote 5C-21C hydrocarbon groups. The polyurethane resin contains 2-9mmol/g of aromatic cycles or alicycles. The polar groups of one selected from among carbonic acid, sulfonic acid, phosphoric acid, salts of those acids, sulfobetaine, carbobetaine, amine and ammonium base are contained with a content of 1×10<-6> to 2×10<-4> eq./g for the polyurethane resin.</p> |
