Polymer particle and method for producing the same

Abstract

A method for producing polymer particles, including (A) polymerizing and granulating a ring-opening polymerizable monomer in a compressive fluid with a catalyst in the presence of a surfactant, or (B) polymerizing and granulating an addition polymerizable monomer in a compressive fluid in the presence of a silicone surfactant.

What is claimed is: 
     
         1 . A method for producing polymer particles, comprising:
 (A) polymerizing a ring-opening polymerizable monomer to produce a polymer while granulating the polymer in a compressive fluid with a catalyst in the presence of a surfactant, or   (B) polymerizing an addition polymerizable monomer to produce a polymer while granulating the polymer in a compressive fluid in the presence of a silicone surfactant.   
     
     
         2 . The method according to  claim 1 , wherein the catalyst is an organic catalyst. 
     
     
         3 . The method according to  claim 2 , wherein the organic catalyst is a nucleophilic nitrogen compound having basicity. 
     
     
         4 . The method according to  claim 2 , wherein the organic catalyst is a cyclic compound containing a nitrogen atom. 
     
     
         5 . The method according to  claim 2 , wherein the organic catalyst is at least one selected from the group consisting of a cyclic amine compound, a cyclic diamine compound, a cyclic triamine compound having a guanidine skeleton, a heterocyclic aromatic organic compound containing a nitrogen atom and N-heterocyclic carbene. 
     
     
         6 . The method according to  claim 5 , wherein the organic catalyst is any one selected from the group consisting of 1,4-diazabicyclo-[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, diphenylguanidine, N,N-dimethyl-4-aminopyridine, 4-pyrrolidinopyridine and 1,3-di-tert-butylimidazol-2-ylidene. 
     
     
         7 . The method according to  claim 1 , wherein the ring-opening polymerizable monomer is a lactide of L-form lactic acids, a lactide of D-form lactic acids, or a lactide of an L-form lactic acid and a D-form lactic acid. 
     
     
         8 . The method according to  claim 1 , wherein the surfactant used in (A) has compatibility to both the compressive fluid and the ring-opening polymerizable monomer. 
     
     
         9 . The method according to  claim 1 , wherein the surfactant used in (A) contains any one selected from the group consisting of a perfluoroalkyl group, a polydimethylsiloxane group and a polyacrylate group. 
     
     
         10 . The method according to  claim 1 , wherein the silicone surfactant used in (B) is a surfactant represented by General Formula (1), (2) or (3) below: 
       
         
           
           
               
               
           
         
         where Me denotes a methyl group; one or two among R 1 , R 2  and R 3  each represent a residue containing a C6-C30 long-chain alkyl group and the other or the others each represent a residue containing a C1-C4 lower alkyl group; and each of m and n is an integer of 1 or greater indicating a number of repeating units, 
       
       
         
           
           
               
               
           
         
         where Me denotes a methyl group, R 4  and R 6  each represent a hydrogen atom or a methyl group, R 5  represents a methylene group or an ethylene group, and each of m and n is an integer of 1 or greater indicating a number of repeating units, 
       
       
         
           
           
               
               
           
         
         where at least one of R 7  and R 8  represents a residue containing a C6-C30 long-chain alkyl group and the other represents a residue containing a C1-C4 lower alkyl group; R 3  to R 13  each represent a hydrogen atom or a C1-C4 lower alkyl group; and each of m and n is an integer of 1 or greater indicating a number of repeating units. 
       
     
     
         11 . The method according to  claim 1 , wherein the compressive fluid is formed of carbon dioxide. 
     
     
         12 . Polymer particles obtained by a method comprising:
 (A) polymerizing a ring-opening polymerizable monomer to produce a polymer while granulating the polymer in a compressive fluid with a catalyst in the presence of a surfactant, or   (B) polymerizing an addition polymerizable monomer to produce a polymer while granulating the polymer in a compressive fluid in the presence of a silicone surfactant.   
     
     
         13 . The polymer particles according to  claim 12 , wherein the polymer particles have a molecular weight distribution Mw/Mn of 2.0 or less, where Mw denotes a weight average molecular weight of the polymer particles and Mn denotes a number average molecular weight of the polymer particles.