Method for the removal and recovery of lactide from polylactide
AssigneeFortum Oil and Gas Oy
InventorsJukka Koskinen, Johan-Fredrik Selin, Nikitas Katsaras, Kari Kaariainen
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Abstract
The invention relates to a method for the removal of lactide from polylactide and recovery of lactide from a lactide-containing gas by cooling the hot lactide-containing gas, wherein a polymer melt traveling through a nozzle forms thin threads the surface area of which is so large that in a normal-pressure or vacuum evaporator the lactide evaporates from the polymer rapidly into a hot carrier-gas flow and the polymer settles under gravity onto a collecting device. A hot lactide-containing gas is cooled rapidly to a temperature below 100° C., whereupon the lactide crystallizes from gas, forming lactide crystals, which are separated from the gas.
Claims18
A method for the removal of lactide from polylactide which comprises evaporating and recovering lactide from a lactide containing gas, wherein a polymer melt traveling through a nozzle forms thin threads the surface area of which is so large that in normal-pressure or vacuum evaporators the lactide evaporates from the polymer rapidly into a hot carrier-gas flow and the polymer settles under gravity on a collecting device, and the hot lactide-containing gas is cooled rapidly in a crystallisation chamber to a temperature below 100° C., where upon the lactide crystallises from gas, forming lactide crystals, which are separated from the gas.
Dependencies are inferred from the claim text.