| 摘要 |
PURPOSE:To prepare a biaxially oriented polyester film having excellent abrasion resistance, scratch resistance and transportability and suitable as a base film for magnetic recording medium, etc. CONSTITUTION:This biaxially oriented polyester film is composed of an acid component composed mainly of an aromatic dicarboxylic acid and a glycol component and contains 100-20,000 ppm of ultrafine calcium carbonate particles satisfying the following conditions of (a) to (d). (a) The particle contains at least 5wt.% of acicular calcium carbonate particles having an aspect ratio (major diameter/minor diameter ratio) of >=2 determined by electron microphotograph (b) 0.005mum<=DS1<=0.5mum, (c) 0.0025mum<=DS2<=0.1mum and (d) 0.01mum<=DP1<=0.4mum. In these formulas, DS1 and DS2 are average particle diameters (mum) of the major diameter and minor diameter determined by electron microphotograph and DP1 is particle diameter (mum) corresponding to 50% cumulative weight counted from the large particle diameter side in the particle size distribution measured by a light-transmission particle size analyzer (SA-CP3; manufactured by Shimadzu Seisakusho Ltd.). |
