| 摘要 |
PROBLEM TO BE SOLVED: To obtain a film with a good winding property for films having a small winding breadth, and excellent abrasion resistance and electromagnetic transformation characteristics. SOLUTION: In this biaxially oriented laminate polyester film, a polyester A layer (A1 layer, A2 layer) is laminated on both the sides of a polyester B layer, and the polyester A layer contains inactive particles A of an average particle diameter of 0.5-5μm at 0.001-0.1wt.%, inactive particles B of an average particle diameter of 0.1-1.0μm at 0.001-1wt.%, and inactive particles C of an average particle diameter of 0.005-0.3μm at 0.05-1wt.%, and an end face dislocation speed W (m/min) at winding a film slit into 1/2 inch breadth, an air escaping time T between the superimposed films (sec), and a film surface roughness at the A1 layer side meet formulas of 0<=W(400, 0<=T<10000, and 0<=T/Ra<500.
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