The invention relates to a crosslinkable foamable
polyurethane composition which is suitable for use as a
polyurethane foam with
flame-retardant properties, containing: - at least one
isocyanate group-containing
prepolymer, - at least one
propellant, and - additives selected from foam stabilizers, catalysts,
viscosity regulators,
cell openers,
flame retardants, non-reactive polymers, dyes or pigments, and / or UV stabilizers, wherein the
polyurethane composition contains, in each case based on the total composition, a) between 0.05 and 2.0 wt.% of at least one
cell opener, b) between 0.5 and 5 wt.% of at least one foam stabilizer, c) and optionally less than 5 wt.% of halogenated and / or
phosphate ester-based
flame retardants. The invention is characterized in that the
cell opener is selected from unsaturated
polyolefin oils, in particular polybutadienes,
paraffin oils,
silicone oils, or any mixtures thereof. The composition is suitable as an
assembly foam with improved flame retardant properties while requiring only very low quantities of conventional flame-retardant additives or while not requiring any conventional flame-retardant additives at all, such as halogenated and / or
phosphate ester-based flame retardants.