| 摘要 |
PURPOSE:To obtain a film having a low heat shrinkage factor and an excellent heat resistance by a method wherein a totally aromatic polyester film is subjected to biaxial stretching and heat shrinkage under specified conditions. CONSTITUTION:A film of a melt-formable totally aromatic polyester containing the isophthalic acid residue and the hydroquinone esidue as major components is biaxially stretched at 180-280 deg.C, then it is heat set at a temperature of not lower than 250 deg.C but lower than the melting point of the aromatic polyester by at least 20 deg.C, and the heat-set film is subjected to a heat shrinkage of at least 1% at a temperature of not lower than 200 deg.C but below the heat setting temperature. Accordingly, a biaxially stretched totally aromatic polyester film having a low heat shrinkage factor and an excellent heat resistance can be produced. |
