Process for producing rigid polyurethane foams

A process for producing rigid polyurethane foams by reacting a) organic polyisocyanates with b) compounds having at least two hydrogen atoms which are reactive toward isocyanate groups in the presence of c) blowing agents, d) catalysts and optionally, e) auxiliaries and additives, wherein a mixture of bl) from 20 to 60 parts by weight of one or more high-functionality polyether alcohols having functionalities of from 3.5 to 5.5 and a hydroxyl number of from 400 to 550 mg KOH/g, b2) from 5 to 25 parts by weight of one or more polyether alcohols based on aromatic and/or aliphatic amines and having functionalities of from 3.5 to 4.5 and a hydroxyl number of from 350 to 500 mg KOH/g, b3) from 5 to 25 parts by weight of one or more polyether alcohols having functionalities of from 2 to 4 and a hydroxyl number of from 150 to 450 mg KOH/g b4) from I to 15 parts by weight of one or more low molecular weight chain extenders and/or crosslinkers having functionalities of from 2 to 3 and a molecular weight Mw of< 400 g/mol and optionally b5) from I to 5 parts by weight of water is used as polyol component b). The polyol component b) of the invention has good storage stability and the rigid polyurethane foams obtained have a good surface quality and adhesion