| abstract |
The invention relates to a process for the fractionation of surfactants, in particular block copolymers of ethylene oxide and propylene oxide. For a specific field of application, a minimization of the surfactant consumption and of the environmental impact is to be achieved by improving the surfactant effect, whereby a standardization of the average molecular weight and the degree of ethoxylation is ensured. The fractionation is carried out by means of selective solvent extraction at a temperature above the reaction point of the block copolymers in aqueous solution with an extractant consisting of hydrocarbons in the boiling range 150-400C. |