| 摘要 |
PROBLEM TO BE SOLVED: To obtain a biaxially oriented polyester film for satisfying both excellent tear straightness and impact strength while retaining mechanical characteristics, smell retaining properties, heat resistance, oil resistance, low hygroscopicity and especially dimensional stability in a dry-heat and a wet-heat environments required for a food packaging material. SOLUTION: This polyester film is characterized by comprising a mixture of 90-70 wt.% of a crystalline polyester resin (A) containing >=80 mol% terephthalic acid and 10-30 wt.% of a block copolyester (B) composed of a crystal segment having >=170 deg.C melting point and a soft polymer having <=100 deg.C melting point or softening point and 400-8,000 molecular weight and having excellent tear straightness in the flow direction of a machine and >=450 J/cm impact strength. |
