Technological watch

The present invention is directed to a value chain return process for polyurethane and polyisocyanurate rigid foams containing at least one additive (A1) which is not chemically bonded to the polymer chain selected from the group consisting of phosphorous ester-based flame retardants, polymerization catalysts and surfactants comprising the steps of providing a composition comprising a comminuted polyurethane or polyisocyanurate rigid foam, wherein the comminuted foam has a content of intact cells of less than 10%, based on the number of intact cells of the not comminuted polyurethane or polyisocyanurate rigid foam, and extraction of the additive (A1) with a solvent at a temperature below 190°C.