Foamed, lightfast polyurethane reaction mixtures, and moldings produced therefrom, comprising: (a) an isocyanate component comprising one or more selected from the group consisting of aliphatic isocyanates, aliphatic isocyanate prepolymers and mixtures thereof; (b) a polyol component having an average molecular weight of 1,000-15,000 g/mol and an average functionality of 2 to 8; (c) a chain extension/crosslinking component comprising one or more selected from the group consisting of polyols and polyamines having a molecular weight of 62-500 g/mol and a functionality of 2 to 8; and (e) a blowing agent comprising an ammonium carbamate salt of formula (I) having at least two OH groups: HO—X—N(R1)H2+−O—C(O)—N(R1)—X—OH   (I) wherein each R1 independently represents a moiety selected from the group consisting of H, C1-C5 alkyl radicals, and —X—OH groups; wherein each X independently represents a moiety selected from the group consisting of —[CR2R3]n— wherein n represents a number of 2 to 6, —(CR2R3)pO—(—CR2R3p]q— wherein p represents a number of 2 to 4 and q represents a number of 1 to 10, and —(CR2R3)N(R4)CR2R3r]s— wherein r represents a number of 2 to 4 and s represents a number of 1 to 10; wherein each R2 and each R3 independently represents a moiety selected from the group consisting of H and C1-C5 alkyl radicals; and wherein each R4 independently represents a moiety selected from the group consisting of H, C1-C5 alkyl radicals, and —X—OH groups.