| 摘要 |
PROBLEM TO BE SOLVED: To obtain polypropylene terephthalate of high heat stability by effecting the polymerization with a specific catalyst instead of Sb compound and Ge compound. SOLUTION: The objective polypropylene terephthalate is obtained by carrying out the polymerization by using a catalyst, instead of Sb compound and Ge compound, that the activity parameter(AP) of the catalyst satisfies the formula: AP (min)<T (min)×2 (AP is the time in minutes required for polymerizing polyethylene terephthalate(PET) at 275 deg.C and 0.1 Torr by using a prescribed catalyst, until the intrinsic viscosity reaches 0.5 dl/g; T is the AP in the case that SbO3 is used as a catalyst, wherein the amount of the SbO3 is 0.05 mol.% based on the acid components in the formed PET, calculated as Sb atom) and the thermal stability index (TD) of the PET polymerized with the catalyst satisfies the formula: TD<=25% (TD is the reduction percentage of the intrinsic viscosity 2 hours after the polymer is molten at 300 deg.C in a nitrogen atmosphere 12 hours after drying 1 gram of PET with an intrinsic viscosity of 0.6 dl/g in a glass test tube at 130 deg.C.
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