| abstract |
The present invention relates to a process for producing translucent polyurethane and polyisocyanurate foams by reaction of a component A, comprising A1 at least one polyol reactive with component B; A2 optionally at least one amine; A3 water and optionally formic acid or at least one physical blowing agent or mixtures thereof; A4 at least one foam stabilizer; A5 optionally auxiliary and/or additive substances; A6 optionally at least one flame retardant; A7 at least one catalyst; and a component B, comprising B1 at least one aliphatic or cycloaliphatic polyisocyanate component or a combination thereof; and B2 optionally at least one hydrophilized isocyanate; and B3 more than or equal to 10 parts by weight and up to 70 parts by weight of an aromatic polyisocyanate component, wherein the parts by weight of B3 are based on the sum of the parts by weight of B1 to B3 which are normalized to 100 parts by weight. The invention is characterized in that the reaction of component A with component B is carried out at an isocyanate index of at least 150, wherein the obtained translucent polyurethane and polyisocyanurate foams have a light transmission according to EN ISO 13468-2:2006 of at least 10% and a haze of at least 70%, determined according to ASTM D1003-13, in each case measured at a layer thickness of 20 mm. The present invention further relates to the polyurethane and polyisocyanurate foams obtained by the process and to the use thereof as a construction element, as a wall element, as a floor element, in buildings, in vehicles or lamps. |