MODIFIED POLYESTER FIBER AND METHOD OF PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To produce an inexpensive modified metal sulfonate group-containing polyester fiber excellent in thermal stability and yarn manufacturing properties by using a polymerization catalyst other than an antimony compound and a germanium compound. SOLUTION: This metal sulfonate group-containing polyester fiber is produced by polymerizing a metal sulfonate group-containing polyester using the polymerization catalyst satisfying the activity parameter represented by formula (1): activity parameter(AP) (min)<T(min)*2 [AP denotes the time (min) required to polymerize a polyethylene terephthalate(PET) having 0.5 dLg-1 intrinsic viscosity at 275 deg.C under 0.1 Torr degree of decompression using the prescribed catalyst; and T denotes the AP when antimony trioxide is used as the catalyst, with the proviso that the antimony trioxide is added in an amount of 0.05 mol% based on an acid component in the produced PET and expressed in terms of antimony atom] so that the resultant PET polymerized using the catalyst satisfies the thermal stability index represented by formula (2) thermal stability index (TD)<25% [TD denotes a decreasing rate (%) of the intrinsic viscosity when 1 g of the PET having 0.6 dLg-1 intrinsic viscosity is placed in a glass test tube, vacuum-dried at 130 deg.C for 12 h and then melted at 300 deg.C for 2 h in a nitrogen atmosphere] without using the antimony compound or the germanium compound.