FREMGANGSMÅDE TIL FREMSTILLING AF HÅRDE POLYURETHAN-SKUM

The invention relates to a method for producing polyurethane hard foams by reacting: A) one or more organic polyisocyanates; B) one or more polyester polyols; C) optionally one or more polyether polyols; D) a fire retardant mixture; E) additional auxiliary agents or additives; F) one or more propellants; and G) catalysts, characterized in that the fire retardant mixture D) contains d1) 10 to 90 wt%, relative to the quantity of the fire retardant mixture, of a fire retardant with a boiling point less than or equal to 220°C, and d2) 10 to 90 wt%, relative to the quantity of the fire retardant mixture, of a phosphorus-containing fire retardant with a boiling point above 220°C, this sum of components d1 ) and d2) yielding 100 wt%.