Polycarbonate copolymer and method of producing the same

Abstract

The problem to be solved by the present invention is to provide a polycarbonate copolymer containing a plant-derived raw material, which is excellent in the mechanical strength and heat-resistant and assured of small refractive index, large Abbe number, small birefringence and excellent transparency. The present invention provides a polycarbonate copolymer containing a constitutional unit derived from a dihydroxy compound represented by the following formula (1) and a constitutional unit derived from an alicyclic dihydroxy compound, wherein the Abbe number is 50 or more and the 5% thermal reduction temperature is 340° C. or more; and a method of producing this polycarbonate copolymer by reacting a dihydroxy compound represented by the following formula (1) and an alicyclic hydroxy compound with a carbonic acid diester in the presence of a polymerization catalyst.

1 . A method of producing a polycarbonate copolymer, comprising reacting a dihydroxy compound represented by the following formula (1) and an alicyclic dihydroxy compound with a carbonic acid diester in the presence of a polymerization catalyst: 
       
         
           
           
               
               
           
         
       
       wherein the polycarbonate copolymer comprises a constitutional unit derived from the dihydroxy compound represented by the formula (1) and a constitutional unit derived from an alicyclic dihydroxy compound, wherein the Abbe number is 50 or more and the 5% thermal reduction temperature is 340° C. or more. 
     
     
         2 . A method of producing a polycarbonate copolymer, comprising reacting a dihydroxy compound represented by the following formula (1) and an alicyclic dihydroxy compound with a carbonic acid diester in the presence of a polymerization catalyst: 
       
         
           
           
               
               
           
         
       
       wherein the polycarbonate copolymer comprises a constitutional unit derived from the dihydroxy compound represented by the formula (1) and a constitutional unit derived from an alicyclic dihydroxy compound, wherein the ratio of the dihydroxy compound represented by the formula (1) and the alicyclic dihydroxy compound to all dihydroxy compounds constituting said copolymer is 90 mol % or more. 
     
     
         3 . The method of producing the polycarbonate copolymer according to  claim 1 , wherein an alkali metal compound, an alkaline earth metal compound or both the compounds are used as the polymerization catalyst. 
     
     
         4 . The method of producing the of producing the polycarbonate copolymer according to  claim 2 , wherein an alkali metal compound, an alkaline earth metal compound or both the compounds are used as the polymerization catalyst.