Patent ID: 6468627
Filing Date: 2002-10-22
Classification: B32B,G11B,Y10T

Abstract:
A polyester film for a magnetic recording medium, comprising at least a polyester layer A and a polyester layer B laminated, wherein a center-line surface average roughness (SRa value) of a layer A-side surface of the film is 2 nm to 4 nm, and a ten-point average surface roughness (SRz value) of the layer A-side surface is 10 nm to 40 nm, and the layer B contains a fine particle &agr; whose average particle size is at least 50 nm and less than 250 nm, and a fine particle &bgr; whose average particle size is at least 250 nm and less than 500 nm, and a content of the fine particle &agr; in the layer B is 0.1 wt. % to 1 wt. %, and a content of the fine particle &bgr; in the layer B is 0.01 wt. % to 0.1 wt. %.