| 摘要 |
PURPOSE:To produce a polyester film having improved low-temperature shrinking properties by stretching a film of a copolyester resin comprising tererphthalic acid, ethylene glycol and a specified comonomer component at a specified temperature, annealing the stretched film and restretching the annealed film. CONSTITUTION:A copolyester resin comprising a dicarboxylic acid component comprising terephthalic acid and about 5-50mol%, based on the acid component, 3-10C aliphatic dicarboxylic acid such as malonic acid and a diol component comprising ethylene glycol and about 5-50mol%, based on the diol component, 3-10C aliphatic diol such as 1,6-hexanediol is melt-extruded to prepare an unstretched polyester film. The unstretched film is stretched at a stretch ratio of 2-5 at a temperature from Tg - 5 deg.C to Tg + 30 deg.C with a stretching machine and annealed for about 3-120sec at a temperature from the stretching temperature to the stretching temperature + 80 deg.C. The annealed film is then restretched at a stretch ratio of 1.05-2 at the annealing temperature to obtain the objective heat-shrinking polyester film. |
