| abstract |
The invention relates to composite elements comprising the following laminar structure: (i) 2 to 20 mm metal; (ii) 10 to 100 mm polyisocyanate polyaddition products having a density ranging from 350 to 1050 kg/m<3> that can be obtained by reacting (a) isocyanates with (b) compounds, which are reactive to isocyanates, in the presence of (f) expanding agents, and; (iii) 2 to 20 mm metal. |