| 摘要 |
PROBLEM TO BE SOLVED: To provide a base film for a thermal transfer ribbon enabling transfer printed images excellent in gradation to be obtained, difficultly being broken, excellent in productivity and having excellent flatness. SOLUTION: This biaxially oriented polyester film mainly comprising polyethylene-2,6-naphthalate contains 0.1-2 wt.% porous silica fine particles having an average particle diameter of 0.5-5 μm and has >=100/mm2 projections having >=0.8 μm. The polymer chain contains a quaternary phosphonium sulfonate having 0.05-40 mmol% ester-forming functional group based on 100 mmol% of a bifunctional carboxylic acid ingredient. |
