Integrated process for the manufacture of lactide

Details Integrated process for the manufacture of lactide Integrated process for the manufacture of lactide

1994-08-18

1996-05-28

Dodson, Shelley A.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

528480, 528481, 528484, 528485, 528357, 528361, C08G 6308, C08F 600

Patent

active

055212786

ABSTRACT:
An integrated process for the manufacture of lactide from a solution of lactic acid in de-ionized water comprising the sequential steps:
A. Dehydrating the aqueous lactic acid in at least two stages to effect condensation polymerization of the lactic acid and the formation of oligomers in which the average number of monomer units is 8-25, the dehydration stages being conducted in equipment fabricated from low ferrous materials;
B. Thermally cracking the oligomers in the presence of depolymerization catalyst to form lactide vapor of which the average residence time within the cracking zone is less than 15 seconds;
C. Condensing the lactide vapor and fractionally distilling the condensate to remove concentrated lactide as a liquid sidestream; and
D. Subjecting the concentrated lactide sidestream to melt crystallization to separate purified lactide having an Acidity Potential less than 6.

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