| 摘要 |
PURPOSE: A method for the solid-state polymerization of polyethyleneterephthalate is provided to increase the overall polymerization degree by reducing the difference of polymerization degree between the surface and inside of PET pellets, to improve the polymerization rate, and accordingly to enhance the productivity. CONSTITUTION: The method for the solid-state polymerization of polyethyleneterephthalate with high degree of polymerization comprises the steps of: crystallizing polyethyleneterephthalate pellets having the polymerization IV value of 0.6 dl/g or less, then subjecting them to primary solid-state polymerization, triturating the resultant mechanically and then subjecting them to secondary solid-state polymerization at a temperature of 200-230 deg.C to prepare polyethylenephthalate having the IV value of 0.9 dl/g or more.
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