Biodegradable resin composition and molded body and production method thereof

Abstract

There is disclosed a biodegradable resin composition containing 100 parts by mass of a biodegradable polyester resin containing not less than 50% by mass of polylactic acid, 0.1 to 10 parts by mass of a layered silicate, 0.1 to 5 parts by mass of a carbodiimide compound and 0.01 to 5 parts by mass of a phosphite organic compound. Alternatively, the biodegradable resin composition contains a phosphite organic compound and at least one additive selected from the group consisting of a hindered phenol compound, a benzotriazole compound, a triazine compound and a hindered amine compound in an amount of 0.01 to 5 parts by mass in total, instead of containing 0.01 to 5 parts by mass of the phosphite organic compound.

1 . A biodegradable resin composition comprising:
 100 parts by mass of a biodegradable polyester resin comprising not less than 50% by mass of polylactic acid;   0.1 to 5 parts by mass of a carbodiimide compound;   0.1 to 10 parts by mass of a layered silicate; and   0.01 to 5 parts by mass of a phosphite organic compound.   
   
   
       2 . The biodegradable resin composition according to  claim 1 , wherein the biodegradable resin composition has a strength-retaining rate of not less than 60% when being held at 60° C. and at a relative humidity of 95 % for 300 hours. 
   
   
       3 . The biodegradable resin composition according to  claim 1 , wherein the biodegradable resin composition has a YI value of not more than 25 as measured by a colorimeter. 
   
   
       4 . The biodegradable resin composition according to  claim 1 , wherein the layered silicate comprises primary, secondary, tertiary or quaternary ammonium ions, pyridinium ions, imidazolium ions or phosphonium ions ionically bonded between layers thereof. 
   
   
       5 . A biodegradable resin composition comprising:
 100 parts by mass of a biodegradable polyester resin comprising not less than 50% by mass of polylactic acid;   0.1 to 5 parts by mass of a carbodiimide compound;   0.1 to 10 parts by mass of a layered silicate;   a phosphite organic compound; and   at least one additive selected from the group consisting of a hindered phenol compound, a benzotriazole compound, a triazine compound and a hindered amine compound, wherein   the biodegradable resin composition comprises the phosphite organic compound and the additive in an amount of 0.01 to 5 parts by mass in total.   
   
   
       6 . The biodegradable resin composition according to  claim 5 , wherein the biodegradable resin composition has a strength-retaining rate of not less than 60% when being held at 60° C. and at a relative humidity of 95 % for 300 hours. 
   
   
       7 . The biodegradable resin composition according to  claim 5 , wherein the biodegradable resin composition has a YI value of not more than 25 as measured by a colorimeter. 
   
   
       8 . The biodegradable resin composition according to  claim 5 , wherein the layered silicate contains primary, secondary, tertiary or quaternary ammonium ions, pyridinium ions, imidazolium ions or phosphonium ions ionically bonded between layers thereof. 
   
   
       9 . A molded body comprising the biodegradable resin composition according to  claim 1 . 
   
   
       10 . A method for producing a biodegradable resin composition comprising:
 adding a layered silicate when melt-mixing the biodegradable resin composition or when polymerizing the biodegradable polyester resin, in producing the biodegradable resin composition according to  claim 1 .   
   
   
       11 . A method for producing a biodegradable resin composition comprising:
 adding a carbodiimide compound and a phosphite compound when melt-mixing the biodegradable resin composition or when polymerizing the biodegradable polyester resin, in producing the biodegradable resin composition according to  claim 1 .   
   
   
       12 . A molded body comprising the biodegradable resin composition according to  claim 5 . 
   
   
       13 . A method for producing a biodegradable resin composition comprising:
 adding a layered silicate when melt-mixing the biodegradable resin composition or when polymerizing the biodegradable polyester resin, in producing the biodegradable resin composition according to  claim 5 .   
   
   
       14 . A method for producing a biodegradable resin composition comprising:
 adding a carbodiimide compound and a phosphite compound when melt-mixing the biodegradable resin composition or when polymerizing the biodegradable polyester resin, in producing the biodegradable resin composition according to  claim 5 .