PROCESS FOR PREPARING A MIXTURE OF LACTIDE DERIVATIVES.

摘要

The present invention relates to three variants for preparing a mixture of cyclic diesters derived from lactic acid and especially a racemate of dilactide. This can proceed, as desired, from the corresponding a-hydroxycarboxylic acids, the corresponding cyclic diesters or oligomers of the corresponding a-hydroxycarboxylic acids. In a painting system (100) comprising at least one spray painting device (116) having at least one application unit for painting workpieces, particularly automotive bodies (102), with a fluid paint, in order to separate the fluid paint overspray, i.e. the paint particles not adhering to the workpieces to be painted and which are picked up and carried along by an air flow permeating the application region of the painting system, from said air flow, and to return the purified air flow in a recirculating circuit back to the application region or to discharge it into the surroundings of the system, the painting system comprises an apparatus (126) for separating fluid paint overspray from a raw gas flow containing overspray particles, wherein said apparatus comprises at least one filter element (172) for separating the overspray from the raw gas. The present invention relates to three variants for preparing a mixture of cyclic diesters derived from lactic acid and especially a racemate of dilactide. This can proceed, as desired, from the corresponding a-hydroxycarboxylic acids, the corresponding cyclic diesters or oligomers of the corresponding a-hydroxycarboxylic acids.