Patent ID: 6773802
Filing Date: 2004-08-10
Classification: B32B,G11B,Y10T

Abstract:
A biaxially oriented laminated polyester film comprising:(A) a first polyester layer which contains (1) at least three types of inert particles: 0.005 to 0.1 wt % of first inert particles having an average particle diameter of 0.4 to 0.7 &mgr;m and a relative standard deviation of particle size distribution of 0.5 or less, 0.05 to 0.3 wt % of second inert particles having an average particle diameter of 0.2 &mgr;m or more and less than 0.4 &mgr;m and a relative standard deviation of particle size distribution of 0.5 or less, and 0.1 to 0.5 wt % of third inert particles having an average particle diameter of 0.01 &mgr;m or more and less than 0.2 &mgr;m; and 0.05 to 0.25 wt % of an ester compound of an aliphatic monocarboxylic acid having 12 or more carbon atoms and a polyhydric alcohol, in a ratio satisfying the following expression: âˆ’0.5x+0.15&lE;y&lE;âˆ’0.5x+0.3 â€ƒwherein x is the content (wt %) of the second inert particles and y is the content (wt %) of the ester compound, â€ƒthe three types of inert particles showing three clearly distinguishable particle size peaks within the above average particle diameter ranges in a particle size distribution curve, respectively, â€ƒand which has (2) a center plane average surface roughness (WRa) of 5 to 20 nm and a 10-point average surface roughness (WRz) of 100 to 300 nm; and â€ƒ(B) a second polyester layer having a center plane average surface roughness (WRa) of 1 to 10 nm, formed on the first polyester layer, â€ƒand having (C) one of Young's moduli in lengthwise and crosswise directions of 6 GPa or more and the other Young's modulus of 4 GPa or more.