| 摘要 |
PURPOSE:To obtain a biaxially oriented polyester film, containing homogeneously dispersed specific calcium carbonate-based platy particles and excellent in abrasion resistance and slipperiness. CONSTITUTION:A biaxially oriented polyester film, containing calcium carbonate-based platy particles having <=1mum, preferably <=0.8mum average particle diameter and >=2.5, preferably >=3.5 average flakiness ratio (plate diameter/ plate thickness) in an amount satisfying the formula 0.0005<=WXD<=0.30 [W is the content (wt.%) of the calcium carbonate-based platy particles; D is the average particle diameter (mum) of the calcium carbonate-based platy particles] and having preferably the value of the WXD within the range of 0.001-0.22. The surface roughness (Ra) of the polyester film is 0.005-0.05mum. The above- mentioned polyester film is a base film for magnetic recording media. |
