Polyester fiber, preparation method therefor, and molded article formed therefrom

Abstract

The present invention relates to a polyester fiber, a preparation method thereof and a molded article prepared therefrom. The polyester fiber comprises a diol moiety derived from isosorbide in a specific amount and is formed into a polyester resin having a specific oligomer content, thereby providing a molded article having excellent saline water resistance, chemical resistance, light resistance and good knot strength, and capable of maintaining high transparency.

1 . A polyester fiber formed from a polyester resin polymerized with a dicarboxylic acid including terephthalic acid or a derivative thereof and a diol including isosorbide, thereby having an alternating structure of an acid moiety derived from the dicarboxylic acid or a derivative thereof 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, and   wherein the polyester resin has an oligomer content of 1.3% by weight or less, and a haze of less than 3% as measured according to ASTM D1003-97 for a specimen having a thickness of 6 mm obtained from the polyester resin.   
     
     
         2 . The polyester fiber of  claim 1 , wherein the haze is less than 2% as measured according to ASTM D1003-97 for a specimen having a thickness of 6 mm obtained from the polyester resin. 
     
     
         3 . The polyester fiber of  claim 1 , wherein the polyester resin has a number average molecular weight of 12,000 to 50,000 g/mol. 
     
     
         4 . The polyester fiber of  claim 1 , wherein the polyester resin has a weight average molecular weight of 45,000 to 225,000 g/mol. 
     
     
         5 . The polyester fiber of  claim 1 , wherein the polyester resin has a molecular weight distribution of 2.5 to 4.5. 
     
     
         6 . The polyester fiber of  claim 1 , wherein the polyester resin includes 5 to 12 mol % of a diol moiety derived from isosorbide and 2 to 5 mol % of a diol moiety derived from diethylene glycol, and a diol moiety derived from residual aliphatic diols based on the total diol moieties. 
     
     
         7 . The polyester fiber of  claim 1 , wherein the polyester resin resin contains 1 ppm to 300 ppm of a polycondensation catalyst, 10 ppm to 5000 ppm of a phosphorus-based stabilizer or 1 ppm to 300 ppm of a cobalt-based decoloring agent based on the central metal atom. 
     
     
         8 . The polyester fiber of  claim 1 , wherein the polyester resin has a glass transition temperature of 82° C. to 105° C. 
     
     
         9 . The polyester fiber of  claim 1 , wherein the polyester fiber has a density of 1.3 g/m 3  to 1.4 g/m 3  measured at 23° C. 
     
     
         10 . The polyester fiber of  claim 1 , wherein the elongation is 14% or more. 
     
     
         11 . The polyester fiber of  claim 1 , wherein the tensile strength is 3.0 g/d or more. 
     
     
         12 . The polyester fiber of  claim 1 , wherein the knot strength is 2.0 g/d or more. 
     
     
         13 . The polyester fiber of  claim 1 , wherein the knot strength retention rate is 40% or more, which is a percentage of the knot strength to the tensile strength. 
     
     
         14 . The polyester fiber of  claim 1 , further comprising at least one additive selected from the group consisting of carbon black, a UV screening agent, an antistatic agent, an impact modifier, an antioxidant, and fine particles. 
     
     
         15 . A method for preparing a polyester fiber comprising the steps of:
 (a) carrying out an esterification reaction or a transesterification reaction of a dicarboxylic acid or a derivative thereof including terephthalic acid or a derivative 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 or a derivative thereof;   (b) subjecting the esterification or transesterification reaction product to a polycondensation reaction to prepare a polyester resin polymerized with a dicarboxylic acid including terephthalic acid or a derivative thereof and a diol including isosorbide, thereby having an alternating structure of an acid moiety derived from the dicarboxylic acid or a derivative thereof 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 (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.   
     
     
         16 . The method of preparing a polyester fiber of  claim 15 , wherein, in step (a), the dicarboxylic acid or derivative thereof is a dicarboxylic acid, and the initial mixing molar ratio of the dicarboxylic acid to the diol is adjusted to 1:101 to 1.05, or
 the dicarboxylic acid or derivative thereof is a dicarboxylic acid alkyl ester or a dicarboxylic acid derivative of a dicarboxylic acid anhydride, and the initial mixing molar ratio of the dicarboxylic acid derivative to the diol is adjusted to 1:2.0 to 1:2.1.   
     
     
         17 . The method of preparing a polyester fiber of  claim 15 , further comprising removing unreacted materials including isosorbide by allowing the product obtained by the esterification reaction or the transesterification reaction to stand under a reduced pressure condition of 400 to 1 mmHg for 0.2 to 3 hours, before the (b) polycondensation reaction. 
     
     
         18 . The method of preparing a polyester fiber of  claim 15 , wherein the undrawn fiber is drawn at a draw ratio of 3 times or more in step (d). 
     
     
         19 . The method of preparing a polyester fiber of  claim 15 , wherein the step (d) is carried out at a temperature of 80° C. to 220° C. 
     
     
         20 . The method of preparing a polyester fiber of  claim 15 , further comprising, after step (b) and before step (c), (b0-1) a step of crystallizing the polymer prepared by polycondensation reaction; and (b0-2) a step of subjecting the crystallized polymer to a solid phase polymerization such that the intrinsic viscosity, which is measured at 35° C. after dissolving the polymer in orthochlorophenol at a concentration of 1.2 g/dl at 150° C. for 15 minutes, is higher than the intrinsic viscosity of the resin obtained in step (b) by 0.05 to 0.40 dl/g. 
     
     
         21 . A molded article prepared from the polyester fiber according to  claim 1 . 
     
     
         22 . The molded article of  claim 21 , wherein the molded article is a fishing gut, a fishing net, a pelt, a rope, a gut for racket, a carpet, a rug, a mat, clothes. 
     
     
         23 . The molded article of  claim 21 , wherein the polyester fiber takes the form of a polyester filament fiber having a diameter of 4 mm or less, and the molded article is a resin molded product for a 3D printer.