Method for the preparation of polyoxyalkylene polyols

A process for preparing a polyoxyalkylene polyol 1) by reacting at least one H-functional starter compound with at least one alkylene oxide, comprising the following steps:

• i) providing a component A) comprising a polyoxyalkylene polyol A1) having a calculated OH number (OHNA1) of 600 to 1060 mg KOH/g and a neutral or acidic salt of an inorganic Brønsted acid by
• i-1) reacting an H-functional starter compound with one or more alkylene oxides
• B1) in the presence of a basic catalyst,
• and
• i-2) reacting the mixture resulting from i-1) with a Brønsted acid having a pKa<1,
• and
• ii) subsequently reacting component A) with one or more alkylene oxides B2) in the presence of a DMC catalyst, wherein
• ii-1) component A) resulting from step i) is admixed with a DMC catalyst and stripped at a temperature TS of not more than 145° C.
• and
• ii-2) the mixture resulting from ii-1) is reacted with one or more alkylene oxides B2) to give a polyoxyalkylene polyol 1), where the quotient of the reaction temperature TR and the alkylene oxide metering rate AR, in which AR is defined as the percentage of the total mass of alkylene oxide to be metered in which is metered in per hour, is
• TR/AR<5.9 [h*° C./%]
• wherein the OH number of the resultant polyoxyalkylene polyol 1) obtained after performance of step ii) is ≥200 mg KOH/g.