METHOD OF TREATING POLYESTER POLYMER AND POLYESTER POLYMER REDUCED IN LOW-BOILING COMPONENT CONTENT

摘要

A method for polyester polymer treatment which comprises heating a polyester polymer C obtained by subjecting at least one cyclic ester compound B comprising ϵ-caprolactone to ring-opening polymerization with a polymer A having a hydroxy group and/or ester bond, at a temperature which is 115°C or higher and below 170°C and is lower than the melting point of the polyester polymer C, while keeping the polymer C in a solid state to thereby remove organic low-boiling components v from the polymer C obtained by the polymerization. Thus, a polyester polymer from which ϵ-caprolactone and caprolactone dimers have been sufficiently removed can be obtained without causing deterioration or alteration of resin properties, deterioration of hue, or decrease of profitability.