| abstract |
The invention relates to a process for producing rigid polyurethane or polyisocyanurate foams by reacting an isocyanate with a polyol in the presence of urethane and/or isocyanurate catalysts, water, optionally further blowing agents, optionally flame retardants and optionally further additives (e.g. fillers, emulsifiers, purely organic stabilizers and surfactants, viscosity reducers, dyes, antioxidants, UV stabilizers, antistatics) using foam stabilizers of the general formula (I) R—Si(CH 3 ) 2 —O—[—Si(CH 3 ) 2 —O—] n —[—Si(CH 3 )(R)—O—] m —Si(CH 3 ) 2 —R, where R=—(CH 2 ) x —O—(CH 2 —CHR′—O) y —R″. |