Polyester resin and method for preparing the same

Abstract

A polyester resin copolymerized with isosorbide and 1,4-cyclohexane dimethanol and having an improved impact strength, and a method for preparing the same are disclosed. The copolymerized polyester resin has an alternating structure of acid moieties which are derived from acid components and diol moieties which are derived from diol components, wherein the acid components comprise terephthalic acid, and the diol components comprise (i) 5˜99 mol % of 1,4-cyclohexanedimethanol and (ii) 1˜60 mol % of isosorbide with respect to the total diol components.

1 . A copolymerized polyester resin having an alternating structure of acid moieties which are derived from acid components and diol moieties which are derived from diol components,
 wherein the acid components comprise terephthalic acid, and the diol components comprise (i) 5˜99 mol % of 1,4-cyclohexanedimethanol and (ii) 1˜60 mol % of isosorbide with respect to the total diol components.   
     
     
         2 . The copolymerized polyester resin according to  claim 1 , wherein the acid components further comprise one or more copolymerization acid components which are selected from the group consisting of aromatic dicarboxylic acid components of 8˜14 carbon numbers, aliphatic dicarboxylic acid components of 4˜12 carbon numbers and mixtures thereof, and the amount of the copolymerization acid components is 0˜50 mol % with respect to the total acid components. 
     
     
         3 . The copolymerized polyester resin according to  claim 1 , wherein the amount of isosorbide (ISB mol %) is in the range of the following Equation 1,
   0.0012( CHDM  mol %) 2 −0.2401( CHDM  mol %)+14.136<= ISB  mol %<=0.0049( CHDM  mol %) 2 −0.2255( CHDM  mol %)+71.176  [Equation 1]
   
       wherein CHDM mol % represents the amount of 1,4-cyclohexane dimethanol. 
     
     
         4 . The copolymerized polyester resin according to  claim 1 , wherein the diol components comprise (i) 8˜91 mol % of 1,4-cyclohexanedimethanol and (ii) 4˜40 mol % of isosorbide with respect to the total diol components. 
     
     
         5 . The copolymerized polyester resin according to  claim 1 , wherein glass transition temperature (Tg) of the polyester resin is more than 90° C., and notch izod impact strength of the polyester resin is more than 50 J/m. 
     
     
         6 . The copolymerized polyester resin according to  claim 1 , wherein intrinsic viscosity of the polyester resin is more than 0.35 dl/g, and the intrinsic viscosity is measured at the temperature of 35° C. while the polyester resin is dissolved with orthochlorophenol to a concentration of 1.2 g/dl. 
     
     
         7 . A polyester resin article selected from the group consisting of a film, a sheet, a drink bottle, a baby bottle, a fiber, and an optical product which is produced with the copolymerized polyester resin according to one of  claims 1 ˜ 6 . 
     
     
         8 . A method for preparing polyester resin, comprising the steps of:
 carrying out an esterification reaction or a trans-esterification reaction of acid components and diol components at the increased pressure of 0.2˜3.0 kg/cm 2  and the temperature of 200˜300° C. during an average retention time of 2˜10 hours; and   carrying out a polycondensation reaction for a product of the esterification reaction or the trans-esterification reaction at the reduced pressure of 400˜0.1 mmHg and at the temperature of 240˜300° C. during an average retention time of 1˜10 hours,   wherein the acid components comprise terephthalic acid, and the diol components comprise (i) 5˜99 mol % of 1,4-cyclohexanedimethanol and (ii) 1˜60 mol % of isosorbide with respect to the total diol components.   
     
     
         9 . The method for preparing polyester resin according to  claim 8 , wherein the amount of isosorbide (ISB mol %) is in the range of the following Equation 1,
   0.0012( CHDM  mol %) 2 −0.2401( CHDM  mol %)+14.136<= ISB  mol %<=0.0049( CHDM  mol %) 2 −0.2255( CHDM  mol %)+71.176  [Equation 1]
   
       wherein CHDM mol % represents the amount of 1,4-cyclohexane dimethanol. 
     
     
         10 . The method for preparing polyester resin according to  claim 8 , wherein the diol components comprise (i) 8˜91 mol % of 1,4-cyclohexanedimethanol and (ii) 4˜40 mol % of isosorbide with respect to the total diol components.