Process of producing polylactic acid-based resin microparticles and polylactic acid-based resin microparticles

Abstract

A process of producing polylactic acid-based resin microparticles includes a dissolving step that forms a system, which can cause phase separation into two phases of a solution phase mainly composed of polylactic acid-based resin (A) having an enthalpy of fusion of less than 5 J/g and a solution phase mainly composed of polymer (B) different from polylactic acid-based resin, by dissolving the polylactic acid-based resin (A) and the polymer (B) different from polylactic acid-based resin in an ether-based organic solvent (C); an emulsion-forming step that forms an emulsion by applying a shear force to the system; and a microparticle-forming step that precipitates polylactic acid-based resin microparticles by contacting the emulsion with a poor solvent which has lower solubility of the polylactic acid-based resin (A) than the ether-based organic solvent (C).

1 . A process of producing polylactic acid-based resin microparticles comprising:
 a dissolving step that forms a system, which can cause phase separation into two phases of a solution phase mainly composed of polylactic acid-based resin (A) having an enthalpy of fusion of less than 5 J/g and a solution phase mainly composed of polymer (B) different from polylactic acid-based resin, by dissolving said polylactic acid-based resin (A) and said polymer (B) different from polylactic acid-based resin in an ether-based organic solvent (C);   an emulsion-forming step that forms an emulsion by applying a shear force to said system; and   a microparticle-forming step that precipitates polylactic acid-based resin microparticles by contacting said emulsion with a poor solvent which has lower solubility of said polylactic acid-based resin (A) than said ether-based organic solvent (C).   
     
     
         2 . The process according to  claim 1 , wherein said ether-based organic solvent (C) has a boiling point of 100° C. or higher. 
     
     
         3 . The process according to  claim 2 , wherein said ether-based organic solvent (C) is diethylene glycol dimethyl ether. 
     
     
         4 . The process according to  claim 1 , wherein said polymer (B) different from a polylactic acid-based resin is a polyvinyl alcohol, a hydroxypropyl cellulose, a polyethylene oxide or a polyethylene glycol. 
     
     
         5 . The process according to  claim 1 , wherein said poor solvent is water. 
     
     
         6 . The process according to  claim 2 , wherein said polymer (B) different from a polylactic acid-based resin is a polyvinyl alcohol, a hydroxypropyl cellulose, a polyethylene oxide or a polyethylene glycol. 
     
     
         7 . The process according to  claim 3 , wherein said polymer (B) different from a polylactic acid-based resin is a polyvinyl alcohol, a hydroxypropyl cellulose, a polyethylene oxide or a polyethylene glycol. 
     
     
         8 . Polylactic acid-based resin microparticles having a sphericity of 90 or greater, a particle diameter distribution index of 1 to 1.8 and a linseed oil absorption of less than 70 ml/100 g, except for hollow microparticles, wherein said polylactic acid-based resin has an enthalpy of fusion of less than 5 J/g. 
     
     
         9 . The polylactic acid-based resin microparticles according to  claim 8 , having a number average particle diameter of 1 to 100 μm.