| 摘要 |
PROBLEM TO BE SOLVED: To provide the film excellent in concealability and made hard to generate roll abrasion by setting the apparent density of a laminated polyester film of copolyester containing rutile type titanium oxide with a specific average particle size and having a specific m.p. and specific intrinsic viscosity so as to satisfy a condition of a specific formula. SOLUTION: A film consists of copolyester layers (A, B) and, if desired, a polyester layer (C) composed of copolyester containing rutile type titanium oxide with a specific average particle size and having a specific m.p. and specific intrinsic viscosity of a polymer part and the apparent density thereof satisfies a condition of formula [whereinρis the apparent density (g/cm<3> ) of the whole of the film,ρo is the calculated density (g/cm<3> ) of the whole of the film,βi is the density (g/cm<3> ) of the polymer part of each of the copolyester layers,ρt is the density (g/cm<3> ) of rutile type titanium oxide, Xi is the thickness (μm) of each of the copolyester layers, Wi is the concn. (wt.%) of titanium oxide in each of the copolyester layers and n is the number of the copolyester layers]. |
