| 摘要 |
PURPOSE:To increase the traveling performance and traveling durability by combinedly using carbon powder of a large particle size and calcium carbonate powder whose particle size is much smaller than that of the carbon powder as a filler in a film for the back coat layer. CONSTITUTION:A film contg. carbon powder of 60-200mmu average particle size and calcium carbonate powder of <=20mmu average particle size dispersed in a binder resin is prepd. to form a back coat layer. The hyperfine calcium carbonate powder increases the Young's modulus of the resin film owing to a reinforcing effect produced by the large surface area, and the film is made smooth because of the small particle size. A resin film contg. only the calcium carbonate powder has, however, a high coefft. of friction yet, so carbon powder of said large particle size is added and arranged continuously or discontinuously on the surface of the film to reduce the coefft. of friction. |
