| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester resin copolymerized with a sulfonate group- containing component but causing slight thermal deterioration during thermal melting, capable of stably producing a high-quality polyester fiber dyable with a basic dye in melt spinning thereof. SOLUTION: This modified polyester resin is characterized by having >=80 mol% ethylene terephthalate units in polyester-composing recurring units and containing an amount of lithium atom satisfying the following formula (1), wherein the polyester is copolymerized with 0.5×10<-2> -8.0×10<-2> mol sulfonate group-containing component per 1 mol whole acidic component of the polyester. Formula (1): 0.02<=Y/X<=1.5 wherein, X is the amount (mol) of the sulfonate group-containing component; and Y is the amount (mol) of the lithium atom.
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