Polyester resin, method for preparing same, and resin molded product formed therefrom

A polyester resin polymerized with a dicarboxylic acid including terephthalic acid or a derivative thereof and a diol including isosorbide and ethylene glycol, 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 6 mol % to 12 mol % of a diol moiety derived from isosorbide, 2 mol % to 5 mol % of a diol moiety derived from diethylene glycol, and remainder of a diol moiety derived from ethylene glycol based on the total diol moieties derived from the diol,
• wherein the polyester resin is prepared by a polycondensation reaction and a solid phase polymerization such that an intrinsic viscosity after the solid phase polymerization, 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, reaches a value of 0.25 dl/g to 0.40 dl/g higher than an intrinsic viscosity of the resin obtained by the polycondensation reaction,
• wherein the intrinsic viscosity of the resin obtained by the polycondensation reaction is 0.60 dl/g to 0.75 dl/g, and the intrinsic viscosity after the solid phase polymerization is 0.85 dl/g to 1.0 dl/g,
• wherein a melting point exists during the first scan through a differential scanning calorimetry (DSC),
• wherein a haze is 1.5% or less as measured according to ASTM D1003-97 for a specimen having a thickness of 6 mm obtained from the polyester resin, and
• wherein the polyester resin has a weight average molecular weight of 70,000 g/mol to 150,000 g/mol.