| 摘要 |
PURPOSE: A co-extruded hot sealing polymer film and its preparation method are provided, to improve the hot sealing property at low temperature and the mechanical properties. CONSTITUTION: The method comprises the steps of preparing the first polymer resin with the limiting viscosity of 0.5-0.7 dl/gr by the polycondensation of dicarboxylic acid containing 80 wt% of terephthalic acid or more and alkylene glycol containing 80 wt% of ethylene glycol or more; preparing the second polymer resin with the melting point of 190-220 deg.C by the polycondensation of dicarboxylic acid containing terephthalic acid and isophthalic acid by the weight ratio of 90:10 to 75:25, and alkylene glycol containing 80 wt% of ethylene glycol; preparing the unstretched sheet by melt co-extruding the first and second polymer resins; stretching the sheet longitudinally to the total longitudinal ratio of 3.5 or more and the crystallization energy of 15 J/g or more; stretching the stretched film horizontally; and heating the sheet at the temperature which is lower than the m.p. of the first polymer resin by about 20 deg.C, for 3-10 seconds.
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