Polyester fiber, preparaion method thereof and molded article formed therefrom

A method for preparing a polyester fiber comprising the steps of:

• (a) carrying out an esterification reaction of a dicarboxylic acid including terephthalic acid thereof and a diol comprising 1 mol to 25 mol of isosorbide and 65 mol to 200 mol of ethylene glycol based on 100 mol of the total dicarboxylic acid;
• (b) subjecting the esterification reaction product to a polycondensation reaction to prepare a polyester resin polymerized with a dicarboxylic acid including terephthalic acid and a diol including isosorbide, thereby having an alternating structure of an acid moiety derived from the dicarboxylic acid and a diol moiety derived from the diol, wherein the polyester resin includes 1 to 20 mol % of a diol moiety derived from isosorbide and 2 to 5 mol % of a diol moiety derived from diethylene glycol based on the total diol moieties derived from the diol;
• (c) melt-spinning the polyester resin obtained in step (b) at 240° C. to 310° C.;
• and
• (d) drawing the melt-spun undrawn fiber obtained in step (c) at a temperature equal to or higher than the glass transition temperature of the polyester resin,
• wherein, in step (a), the initial mixing molar ratio of the dicarboxylic acid to the diol is adjusted to 1:1.01 to 1.05, and
• wherein in step (b), the polycondensation is carried out so that an intrinsic viscosity, which is measured at 35° C. after dissolving the product obtained by the polycondensation reaction in orthochlorophenol at a concentration of 1.2 g/dl at 150° C. for 15 minutes, reaches 0.45 dl/g to 0.75 dl/g,
• wherein the polyester resin has an alternating structure of an acid moiety derived from the dicarboxylic acid and diol moieties derived from the diol, the dicarboxylic acid includes 90 mol % or more of the terephthalic acid based on the total dicarboxylic acid, and the polyester resin includes 1 to 20 mol % of a diol moiety derived from isosorbide, 2 to 5 mol % of a diol moiety derived from diethylene glycol, and the remainder of a diol moiety derived from ethylene glycol, based on the total diol moieties derived from the diol, and
• wherein the polyester resin has a molecular weight distribution of 2.8 to 4.0.