Polyester resin

Abstract

The present invention relates to a polyester resin. The polyester resin is useful for bottles, sheets, multilayer sheets, stretched films and fiber applications due to excellent heat resistance and transparency, and in particular, the polyester resin has little deterioration of physical properties such as yellowing, etc., during processing

What is claimed is: 
     
         1 . A polyester resin having a structure in which a dicarboxylic acid or a derivative thereof that includes a terephthalic acid or a derivative thereof, and a diol that includes isosorbide are polymerized so that an acid moiety derived from the dicarboxylic acid or the derivative thereof and a diol moiety derived from the diol are repeated,
 wherein the diol moiety derived from the isosorbide has a content of 0.5 to 20 mol % with respect to a total diol moiety derived from the diol, and   when a standard solution in which isosorbide is dissolved in chloroform at a concentration of 150 μg/mL, and a resin solution obtained by dissolving a component extracted from 0.5 g of the polyester resin in 5 mL of chloroform using a solvent in which cyclohexane and isopropyl alcohol are mixed at a volume ratio of 2.5:97.5, are analyzed by gas chromatography, respectively, a peak area ratio of a peak of the resin solution confirmed at the same retention time to a peak confirmed in the analysis of the standard solution (peak area of the resin solution/peak area of the standard solution) is 1.0 or less.   
     
     
         2 . The polyester resin of  claim 1 , wherein:
 the dicarboxylic acid or the derivative thereof includes 0 to 50 mol % of at least one selected from the group consisting of a C8-C14 aromatic dicarboxylic acid or a derivative thereof and a C4-C12 aliphatic dicarboxylic acid or a derivative thereof, as a dicarboxylic acid or a derivative thereof other than the terephthalic acid or the derivative thereof, with respect to a total dicarboxylic acid or a derivative thereof.   
     
     
         3 . The polyester resin of  claim 1 , wherein:
 the diol moiety derived from isosorbide has a content of 1 to 20 mol % with respect to the total diol moiety derived from the diol.   
     
     
         4 . The polyester resin of  claim 1 , wherein:
 the polyester resin includes a residue derived from diethylene glycol at a content of 6 mol % or less with respect to the total diol moiety derived from the diol.   
     
     
         5 . The polyester resin of  claim 1 , wherein:
 the polyester resin has a number average molecular weight of 15,000 to 50,000 g/mol.   
     
     
         6 . The polyester resin of  claim 1 , wherein:
 the polyester resin has a glass transition temperature of 80 to 105° C.   
     
     
         7 . The polyester resin of  claim 1 , wherein:
 the polyester resin has an intrinsic viscosity of 0.7 to 1.4 dl/g as measured at 35° C. after being dissolved in ortho-chlorophenol at a concentration of 1.2 g/dl.   
     
     
         8 . The polyester resin of  claim 1 , wherein:
 a color b value of a specimen having a size of 30 mm×30 mm×3 mm (width×length×thickness) obtained by injection molding the polyester resin at 290° C. is −2.0 to 3.0 as measured by a color difference meter.   
     
     
         9 . The polyester resin of  claim 1 , wherein:
 the polyester resin is used as injection-molded articles, bottles, sheets, multilayer sheets, stretched films or fibers.   
     
     
         10 . A manufacturing method of the polyester resin of  claim 1 , comprising:
 (a) performing an esterification reaction or a transesterification reaction on (i) a dicarboxylic acid or a derivative thereof that includes a terephthalic acid or a derivative thereof and (ii) a diol including 0.5 to 25 mol % of isosorbide with respect to a total diol; and   (b) performing a polycondensation reaction on a product obtained by the esterification reaction or the transesterification reaction.   
     
     
         11 . The manufacturing method of  claim 10 , wherein:
 a polycondensation catalyst, a stabilizer, a coloring agent, a crystallizer, an antioxidant or a branching agent is added to a slurry before (a) the esterification reaction or the transesterification reaction starts or to the product after (a) the esterification reaction or the transesterification reaction is completed.   
     
     
         12 . The manufacturing method of  claim 10 , wherein:
 the dicarboxylic acid or the derivative thereof is a dicarboxylic acid, and an initial mixing molar ratio of the dicarboxylic acid or the derivative thereof and the diol is 1:1.01 to 1.04.   
     
     
         13 . The manufacturing method of  claim 10 , wherein:
 the dicarboxylic acid or the derivative thereof is a dicarboxylic acid alkyl ester or a dicarboxylic acid anhydride, and an initial mixing molar ratio of the dicarboxylic acid or the derivative thereof and the diol is 1:2.0 to 1:2.1.   
     
     
         14 . The manufacturing method of  claim 10 , further comprising:
 before (b) the polycondensation reaction, allowing the reaction product obtained by the esterification reaction or the transesterification reaction to stand under a reduced pressure of 400 to 1 mmHg for 0.2 to 3 hours.   
     
     
         15 . The manufacturing method of  claim 10 , wherein:
 (b) the polycondensation reaction is performed under a pressure of 400 to 0.01 mmHg.   
     
     
         16 . The manufacturing method of  claim 10 , further comprising:
 after (b) the polycondensation reaction, (c) performing crystallization on a polymer prepared by the polycondensation reaction and (d) performing solid-phase polymerization on the crystallized polymer.   
     
     
         17 . The manufacturing method of  claim 16 , wherein:
 the crystallized polymer obtained after (c) the crystallization is washed with water to remove unreacted raw material.   
     
     
         18 . The manufacturing method of  claim 16 , wherein:
 (d) the solid-phase polymerization is performed on the crystallized polymer so that an intrinsic viscosity measured at 35° C. after being dissolved in ortho-chlorophenol at a concentration of 1.2 g/dl at 150° C. for 15 minutes reaches 0.80 dl/g or more.