Patent ID: 6319589
Filing Date: 2001-11-20
Classification: B29C,B29K,B32B,G11B,Y10S,Y10T

Abstract:
A biaxially oriented laminate polyester film comprising a first polyester layer and a second polyester layer, whereinthe first polyester layer has a thickness (t.sub.A) of 0.3 to 5 .mu.m, the second polyester layer contains an inert fine particle lubricant and has a thickness (t.sub.B) of 1.5 to 9 .mu.m, and the first polyester layer and the second polyester layer satisfy the following expressions (1) to (4):WRa(B)>WRa(A) (1)0.5.ltoreq.t.sub.B /t.ltoreq.0.9 (2)10<t.sub.B /d.sub.B.ltoreq.60 (3)t=3 to 10 .mu.m (4)wherein WRa(A) is the center plane average roughness (nm) of the exposed surface of the first polyester layer, WRa(B) is the center plane average roughness (nm) of the exposed surface of the second polyester layer, t.sub.B is the thickness (.mu.m) of the second polyester layer, t is the sum of t.sub.A and t.sub.B, t.sub.A is the thickness (.mu.m) of the first polyester layer, and d.sub.B is the average particle diameter (.mu.m) of the inert fine particle lubricant contained in the second polyester layer.