Polysiloxane-polylactide block copolymer and preparation method thereof

Abstract

The present invention relates to a polysiloxane-polylactide block copolymer and a preparation method thereof, in which the polysiloxane-polylactide block copolymer has improved impact resistance and flexibility, compared to the conventional polylactide resins and can be prepared by ring-opening polymerization of lactide monomers in the presence of a polymerization initiator of polysiloxane.

1 . A polysiloxane-polylactide block copolymer, comprising a repeating unit of the following Chemical Formula 1 and a repeating unit of the following Chemical Formula 2: 
       
         
           
           
               
               
           
         
         wherein m is an integer of 5 to 150, and 
         R 1  and R 2  are the same as or different from each other, and are each independently hydrogen, substituted or unsubstituted alkyl having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 10 carbon atoms, or substituted or unsubstituted aryl having 6 to 10 carbon atoms. 
       
     
     
         2 . The polysiloxane-polylactide block copolymer according to  claim 1 , wherein the block copolymer comprises 1 to 30% by weight of the repeating unit of Chemical Formula 2. 
     
     
         3 . The polysiloxane-polylactide block copolymer according to  claim 1 , having a weight average molecular weight of 50,000 to 1,000,000 g/mol. 
     
     
         4 . The polysiloxane-polylactide block copolymer according to  claim 1 , wherein its tensile modulus measured according to ASTM D638 is 2.5 GPa or less. 
     
     
         5 . The polysiloxane-polylactide block copolymer according to  claim 1 , wherein its tensile strength measured according to ASTM D638 is 100 to 700 Kg/cm 2  and its elongation measured according to ASTM D638 is 2 to 20%. 
     
     
         6 . The polysiloxane-polylactide block copolymer according to  claim 1 , wherein its notched Charpy impact strength measured according to ASTM D256 is 5 to 50 Kg·m/m. 
     
     
         7 . A preparation method of a polysiloxane-polylactide block copolymer, comprising the step of ring-opening polymerization of lactide monomers in the presence of a polysiloxane compound of the following Chemical Formula 3: 
       
         
           
           
               
               
           
         
         wherein m is an integer of 5 to 150, 
         R 1  and R 2  are the same as or different from each other, and are each independently hydrogen, substituted or unsubstituted alkyl having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 10 carbon atoms, or substituted or unsubstituted aryl having 6 to 10 carbon atoms, and 
         X and Y are each independently an alkoxy group having 1 to 12 carbon atoms or a hydroxyl group. 
       
     
     
         8 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 7 , wherein the polysiloxane compound of Chemical Formula 3 is added in an amount of 1 to 50 parts by weight, based on 100 parts by weight of the lactide monomer. 
     
     
         9 . The preparation method of polysiloxane-polylactide block copolymer according to  claim 7 , wherein the polysiloxane compound of Chemical Formula 3 has a number average molecular weight of 300 to 30,000 g/mol. 
     
     
         10 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 7 , wherein the ring-opening polymerization of lactide monomers is performed in the presence of an organic metal complex catalyst of the following Chemical Formula 4: 
       
         
           
           
               
               
           
         
         wherein n is an integer of 0 to 15; p is an integer of 0 to 2; a is 0 or 1; M is Sn or Zn; R 3  and R 5  are the same as or different from each other, and are each independently hydrogen, substituted or unsubstituted alkyl having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 10 carbon atoms, or substituted or unsubstituted aryl having 6 to 10 carbon atoms; R 4  is substituted or unsubstituted alkylene having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkylene having 3 to 10 carbon atoms, or substituted or unsubstituted arylene having 6 to 10 carbon atoms; and A 1  and A 2  are each independently an alkoxy group having 1 to 12 carbon atoms or a carboxyl group. 
       
     
     
         11 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 7 , wherein the ring-opening polymerization of lactide monomers is performed in the presence of a catalyst including compounds of the following Chemical Formula 5 and 6:
   R 3 N═C═N—R 4  n N═C═N—R 5   [Chemical Formula 5]
   wherein n is an integer of 0 to 15; R 3  and R 5  are the same as or different from each other, and are each independently hydrogen, substituted or unsubstituted alkyl having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkyl having 3 to 10 carbon atoms, or substituted or unsubstituted aryl having 6 to 10 carbon atoms;   R 4  is substituted or unsubstituted alkylene having 3 to 10 carbon atoms, substituted or unsubstituted cycloalkylene having 3 to 10 carbon atoms, or substituted or unsubstituted arylene having 6 to 10 carbon atoms;
   MA 1   p A 2   2-p   [Chemical Formula 6]
 
   wherein M is Sn or Zn, p is an integer of 0 to 2, and A 1  and A 2  are each independently an alkoxy group having 1 to 12 carbon atoms or a carboxyl group.   
     
     
         12 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 10 , wherein R 3  and R 5  are each independently a monovalent phenyl group substituted with an alkyl group having 1 to 10 carbon atoms, or an alkyl or cycloalkyl group having 3 to 10 carbon atoms, and
 R 4  is a bivalent phenylene group substituted with an alkyl group having 1 to 10 carbon atoms or an alkylene or cycloalkylene group having 3 to 10 carbon atoms.   
     
     
         13 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 10 , wherein MA 1   p A 2   2-p  is tin(II) 2-ethylhexanoate(Sn(Oct) 2 ). 
     
     
         14 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 10 , wherein the organic metal complex catalyst of Chemical Formula 4 is added at a ratio of 0.001 to 0.1 mole, based on 100 moles of the lactide monomer. 
     
     
         15 . The preparation method of polysiloxane-polylactide block copolymer according to  claim 11 , wherein each of the compounds of Chemical Formula 5 and 6 is added at a ratio of 0.001 to 0.1 mole, based on 100 moles of the lactide monomer. 
     
     
         16 . The preparation method of polysiloxane-polylactide block copolymer according to  claim 7 , wherein an initiator including a hydroxyl-containing compound is added at a ratio of 0.001 to 1 mole, based on 100 moles of the lactide monomer, so as to perform the ring-opening polymerization. 
     
     
         17 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 7 , wherein the ring-opening polymerization is performed by bulk polymerization. 
     
     
         18 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 7 , wherein the ring-opening polymerization is performed at a temperature of 120 to 200° C. for 0.5 to 8 hours. 
     
     
         19 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 11 , wherein R 3  and R 5  are each independently a monovalent phenyl group substituted with an alkyl group having 1 to 10 carbon atoms, or an alkyl or cycloalkyl group having 3 to 10 carbon atoms, and
 R 4  is a bivalent phenylene group substituted with an alkyl group having 1 to 10 carbon atoms or an alkylene or cycloalkylene group having 3 to 10 carbon atoms.   
     
     
         20 . The preparation method of the polysiloxane-polylactide block copolymer according to  claim 11 , wherein MA 1   p A 2   2-p  is tin(II) 2-ethylhexanoate(Sn(Oct) 2 ).