| 摘要 |
The present invention relates to a method for decreasing the cyclic oligomer content in polyester product; during the manufacturing process of polyethylene terephthalate, adding at least one selected from the group consisting of calcium phosphate having Ca3(PO4)2 or Ca5OH(PO4)3 structure and of carboxy phosphonic acid having a structure (1) as follows: wherein R1, R2, and R3 are alkyls or hydrogen atoms, R is an alkyl; whereby not only is the production of cyclic oligomer in ester chips effectively restrained, but also the cyclic oligomer regenerated in the rear-stage melting process is decreased.
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