Polyester resin, method for preparing same, and resin molded product formed therefrom
The present invention relates to a polyester resin. The polyester resin contains a particular content of diol moieties, derived from isosorbide and diethylene glycol, and thus can provide a resin molded product exhibiting high transparency in spite of a large wall thickness thereof.
1. 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.
2. The polyester resin of claim 1 , wherein the dicarboxylic acid or a derivative thereof is a dicarboxylic acid or a derivative thereof other than terephthalic acid or a derivative thereof, which includes at least one selected from the group consisting of an aromatic dicarboxylic acid having 8 to 14 carbon atoms or a derivative thereof and an aliphatic dicarboxylic acid having 4 to 12 carbon atoms or a derivative thereof in an amount of 0 to 50 mol % based on the total dicarboxylic acids or derivatives thereof.
3. The polyester resin of claim 1 , wherein the polyester resin has a number average molecular weight of 15,000 to 50,000 g/mol.
4. The polyester resin of claim 1 , wherein the polyester resin has a molecular weight distribution of 2.5 to 4.0.
5. The polyester resin of claim 1 , wherein the polyester resin has a melting point of 200° C. to 250° C. as measured during the first scan through a differential scanning calorimetry (DSC).
6. The polyester resin of claim 1 , wherein the polyester resin has a glass transition temperature of 85° C. or more.
7. The polyester resin of claim 1 , wherein the polyester resin is used for a bottle, a hot fill jar, a high-pressure vessel, a sheet, a drawn film or a fiber.
8. A resin molded article prepared from the polyester resin according to claim 1 .
9. The resin molded article of claim 8 , having a wall thickness of 4.5 mm or more.