Polyester copolymer, uneven dyeing reduction agent, polyester resin composition for melt-spinning, polyester fiber production method, and polyester fiber

Abstract

A polyester copolymer (B) has a structural unit derived from polyalkylene glycol (B1). The polyalkylene glycol (B1) has an average molecular weight within the range of 400-4,000. The polyester copolymer (B) contains the structural unit derived from the polyalkylene glycol (B1) within the range of 15-60 mass%, and contains a low molecular weight component having a molecular weight of 600 or less at 15 mass% or less. Before use for melt-spinning, the polyester copolymer (B) is mixed with a polyester (A) such that the content of the polyester copolymer (B) is within the range of 0.5-15 parts by mass with respect to the total 100 parts by mass of the polyester (A) and the polyester copolymer (B).

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