Patent ID: 6551686
Filing Date: 2003-04-22
Classification: B32B,B41M,G11B,Y10S,Y10T

Abstract:
A biaxially oriented, coextruded polyester film comprising at least three layers and whose two surfaces are formed by outer layers A and C, where a base layer B is located between these outer layers, wherein layers A and C have different compositions, and wherein the outer layer Ahas an Ra value of &lE;15 nm, and has an Rz value of &lE;150 nm and has a number of elevations Na per 0.36 mm2 which is related as follows to their respective heights ha: A1Â·eâˆ’B1Â·ha&lE;Na&lE;A2Â·eâˆ’B2Â·haâ€ƒâ€ƒ(1) whereA1=300, A2=7000 B1=7.0, B2=8.0 and 0.01 &mgr;m&lE;ha&lE;1.0 &mgr;m and the outer layer Chas an Ra value which is greater than that of the outer layer A and has a number of elevations Nc per 0.36 mm2 which is related as follows to their respective heights hc: Nc&lE;FÂ·eâˆ’GÂ·hcâ€ƒâ€ƒ(2) whereF=20,000, G=9.0 and where the haze per unit thickness is &lE;0.4%/&mgr;m.