POLYESTER COPOLYMER AND PROCESS FOR PRODUCING THE SAME

摘要

PURPOSE: Provided are a polyester copolymer excellent in dyeing property and radiation property and a process for producing the polyester copolymer, which has high productivity and low producing cost. CONSTITUTION: The polyester copolymer is produced by melting and mixing 15-50wt% of a polyethylene terephthalate(PET)(a) and 50-85wt% of a polyethylene terephthalate(PET)(b) at a temperature of 265-300deg.C for 5-30 minutes, wherein the PET(a) has an intrinsic viscosity of 0.35-0.7dl/g and is produced by copolymerizing 3.5-10mol% (based on an acid component) of 5-sodium sulfodimethyl isophthalate, 5-sodium sulfo-beta-dihydroxyethyl isophthalate, or a mixture thereof and 3.5-10wt% (based on the copolymer) of polyalkylene glycol or 3.5-10mol% (based on the acid component) of aliphatic dicarboxylic acid and the PET(b) has an intrinsic viscosity of 0.4-0.9dl/g. The produced polyester copolymer has an intrinsic viscosity of 0.35-0.7dl/g and contains 1.0-5.0mol% of the 5-sodium sulfodimethyl isophthalate, the 5-sodium sulfo-beta-dihydroxyethyl isophthalate, or the mixture thereof and 1.0-5.0wt% of the polyalkylene glycol or 1.0-5.0mol% of the aliphatic dicarboxylic acid.