Process for producing solid polyurethane moldings

A process for the production of a solid polyurethane molding having a flexural modulus of elasticity>1800 N/mm2 (according to DIN 53 457) by the casting process comprising reacting

• a) a diisocyanate and/or polyisocyanate from the diphenylmethane series
• with a polyol component comprising
• b) from 30 to 70 wt. %, relative to total weight of components b),
• c) and d), of a polyether polyol having a number-average molecular weight of from 149 to 999 g/mol, which is initiated with an aliphatic amine,
• c) from 25 to 50 wt. %, relative to total weight of components b), c) and d), of a polyether having a number-average molecular weight of from 1,000 to 16,000 g/mol, at least one group capable of reacting with an isocyanate group and having a maximum of 80% of primary hydroxyl groups,
• d) from 0 to 30 wt. %, relative to total weight of components b), c) and d), of a polyether polyol started with a polyhydroxyl compound and having a (number-average) molecular weight of from 62 to 999 g/mol, optionally in the presence of
• e) a catalyst that accelerates an isocyanate addition reaction, and optionally
• f) any of the auxiliary substances and additives known to those skilled in the art of polyurethane chemistry,
• in which the type and proportions of components b) to d) are selected so an average hydroxyl value of the mixture formed from these components is greater than 300 mg KOH/g.