Described herein is a process for preparing a polyurethane elastomer including the steps of (A) preparing an isocyanate prepolymer (a), where the isocyanate prepolymer has an isocyanate content in the range of ≥1 wt.-% to ≤9 wt.-%, and (B) preparing a reaction mixture by mixing at least one epoxy compound (b) with the isocyanate prepolymer (a) in presence of at least one catalyst (c), and where the amount of the alkali metal or alkaline earth metal salt is 0.00001 to 0.1 mol per kg of the total weight of the isocyanate prepolymer (a), the epoxy compound (b) and the catalyst (c), and heating the mixture to at least 80° C. to obtain the polyurethane elastomer. Also described herein are a polyurethane elastomer obtained by process and a method of using the polyurethane elastomer as part of a roller or as a sealant.