Stable lactide particles

Abstract

The present invention is directed to a method for the manufacture of 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 are obtained via a flaking process, comprising the contacting of a continuous flow of molten lactide with a surface on which the lactide solidifies and subsequently is removed from said surface.

1 . Method for the manufacture of stable lactide particles comprising contacting a continuous flow of molten lactide with a surface having a temperature lower than the melting point of the lactide, allowing the lactide melt to solidify on said surface, and subsequently removing the solid lactide from that surface. 
     
     
         2 . Method according to  claim 1  wherein said surface is cooled by external or internal means. 
     
     
         3 . Method according to  claim 1  wherein said removal is by means of contacting the surface with the solidified lactide with a scraping device. 
     
     
         4 . Method according to  claim 1  wherein said method is carried out with a drum flaker or belt flaker. 
     
     
         5 . Method according to  claim 1  wherein the obtained lactide particles are sieved. 
     
     
         6 . Stable lactide particle obtainable by the method according to  claim 1 . 
     
     
         7 . Stable lactide particle having a surface area per unit of volume of from 1000 to 10000 m −1 . 
     
     
         8 . Stable lactide particle of  claim 7  having a surface area per unit of volume of from 1000 to 3000 m −1 . 
     
     
         9 . Stable lactide particle of  claim 7  having a surface area per unit of volume of from 3000 to 10000 m −1 . 
     
     
         10 . Stable lactide particle wherein the lactide particle comprises more than 95% by weight lactide. 
     
     
         11 . Stable lactide particle according to  claim 10  wherein the lactide present in the particle contains more than 95% by weight D-lactide. 
     
     
         12 . Stable lactide particle according to  claim 11  wherein the lactide present in the particle contains more than 95% by weight L-lactide. 
     
     
         13 . Stable lactide particle wherein the water content is below 200 ppm. 
     
     
         14 . Stable lactide particle wherein the free lactic acid content is below 50 milli-equivalents per kg lactide (meg.Kg −1 ) 
     
     
         15 . Stable lactide particle according to  claim 10  wherein the lactide particle comprises more than 98.5% by weight lactide. 
     
     
         16 . Stable lactide particle according to  claim 10  wherein the lactide particle comprises more than 99.5% by weight lactide. 
     
     
         17 . Stable lactide particle according to  claim 10  wherein the lactide present in the particle contains more than 98.5% by weight D-lactide. 
     
     
         18 . Stable lactide particle according to  claim 10  wherein the lactide present in the particle contains more than 99.5% D-lactide by weight. 
     
     
         19 . Stable lactide particle according to  claim 11  wherein the lactide present in the particle contains more than 98.5% by weight L-lactide. 
     
     
         20 . Stable lactide particle according to  claim 11  wherein the lactide present in the particle contains more than 99.5% by weight L-lactide. 
     
     
         21 . Stable lactide particle according  claim 13  wherein the water content is below 100 ppm. 
     
     
         22 . Stable lactide particle according  claim 13  wherein the water content is below 50 ppm. 
     
     
         23 . Stable lactide particle according to  claim 14  wherein the free lactic acid content is below 50 milli-equivalents per kg lactide (meg.Kg −1 ) below 20 meg.Kg −1 . 
     
     
         24 . Stable lactide particle according to  claim 14  wherein the free lactic acid content is below 50 milli-equivalents per kg lactide meg.Kg −1 ) between 0 and 10 meq.Kg −1 .