| 摘要 |
Terephthalic acid or 2,6-naphthalene dicarbonic acid, aromatic dicarbonic acid or its ester forming derivatives and ethylene glycol are used as starting materials for this invention. At least 80% of repeated structural unit of polyester is preferably ethyleneterephthlate or ethylene 2,6-naphthalate and optinally other additives such as heat stabilizer and antioxidant. Biaxially oriented film in this invention has physical properties; d25/d75 is less than 2.00, the range of d50 is from 0.7 to 1.50, where d represents particle size:um), a:b:c=1:(1-15):(1-1.5), where a, b, c represent the lengths of sides of hexahedral calcite. |
