Stable lactide particles

Abstract

The present invention is directed to stable lactide particles, more specifically lactide particles which are stable enough to be stored and transported at room temperature and have a quality high enough for use as starting material for polylactic acid. The lactide particles have a surface/volume ratio of the particle is lower than 3000. Preferably the lactide in the particle has an optical purity of at least 95%. The lactide particles are prepared by subjecting lactide to a shaping step comprising extrusion, pastillation, prilling, tabletting, or flaking.

1 . Stable lactide particle wherein the surface/volume ratio of the particle is lower than 3000 m −1 . 
     
     
         2 . Stable lactide particle according to  claim 1 , wherein the lactide particle comprises more than 95% by weight lactide, preferably more than 98.5% by weight lactide, most preferably more than 99.5% by weight. 
     
     
         3 . Stable lactide particle according to  claim 1 , wherein the lactide present in the particle contains more than 95% by weight D-lactide, preferably more than 98.5% by weight D-lactide, most preferably more than 99.5% D-lactide by weight. 
     
     
         4 . Stable lactide particle according to  claim 1 , wherein the lactide in the particle contains more than 95% by weight L-lactide, preferably more than 98.5% by weight L-lactide, most preferably more than 99.5% by weight. 
     
     
         5 . Stable lactide particle according to any one of the preceding claims, which is substantially hemi-spherical. 
     
     
         6 . Stable lactide particle according to any one of the preceding claims wherein the average particle diameter is at least 3 millimeters. 
     
     
         7 . Stable lactide particle according to any one the preceding claims wherein the water content is below 200 ppm, preferably below 100 ppm, and most preferably below 50 ppm. 
     
     
         8 . Stable lactide particle according to any one the preceding claims wherein the free lactic acid content is below 50 milli-equivalents per Kg lactide (meq·Kg −1 ), preferably below 20 meq·Kg −1 , and most preferably between 0 and 10 meq·Kg −1 . 
     
     
         9 . Process for the preparation of lactide particles wherein lactide is subjected to a shaping process to form particles having a surface/volume ratio lower than 3000 m −1 . 
     
     
         10 . Process according to  claim 9  wherein the shaping process comprises extrusion, pastillation, prilling, tabletting, or flaking. 
     
     
         11 . Process according to  claim 9  wherein a lactide is extruded or compressed to form cylindrical, cubical or rod-shaped particles. 
     
     
         12 . Process according to  claim 9  wherein a lactide melt is pastillated to form substantially hemi-spherical particles.