| 摘要 |
PURPOSE:To improve wear resistance, durability and mechanical properties and to decrease the coefft. of temp. and humidity expansion by providing a magnetic layer contg. a specific range of a polyurethane resin, cellulosic resin, a vinyl chloride copolymer, an org. acid-modified silicone oil and a higher fatty acid on a base. CONSTITUTION:A magnetic layer which contains, as a binder, a soft type polyurethane resin having <200kg/cm<2> tensile and >=900% elongation at rupture, a hard type polyurethane resin having >=200kg/cm<2> tensile strength and <900% elongation at rupture, a cellulosic resin and vinyl chloride copolymer and contains an org. acid-modified silicone oil and higher fatty acid is provided on a base. The soft type polyurethane resin and the hard type polyurethane resin are the polyurethane resin having the properties belonging to the regions A2 and B2 when shown by the characteristic curve of the load (kg/cm<2>) thereof versus the elongation (%) at rupture. The weight ratio of the cellulosic resin and the vinyl chloride copolymer with respect to the polyurethane resin is preferably in a 85/15-50/50 range for the entire part of the binder system. |
