| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for increasing the molecular weight of a polycondensate in a molten state and/or modifying the polycondensate by adding a blend consisting of a polyfunctional anhydride, a specific polyfunctional compound and a phosphonate to the polycondensate. SOLUTION: A blend comprising (A) a polyfunctional anhydride (e.g. pyromellitic acid dianhydride), (B) a polyfunctional compound containing a functional group to be reacted with an anhydride group of the component A (e.g. glycerol) and (C) a phosphonate [e.g. a compound of the formula (R1 is H, isopropyl, or the like; R2 is H, a 1-4C alkyl, or the like; R3 is a 1-20C alkyl, or the like; R4 is H, a 1-20C alkyl, or the like; (n) is 1-6; (r) is 1-4), or the like] is added to a polycondensate (e.g. polyethylene terephthalate) to increase the molecular weight of the polycondensate in a molten state and/or modifying the polycondensate. This method is useful for recycling a recovered container of PET beverage, and the like.
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