| 摘要 |
<p>1. A process for the preparation of flexible polyurethane foams having high solidity from a foaming composition comprising an organic polyisocyanate, a catalyst, an expansion agent and a polyether-polyol, characterized in that the said composition contains in addition 0.1 to 30% by weight, with respect to the polyether-polyol, of a hydroxyl resin having a softening temperature between 70 and 150 degrees C and a hydroxyl index between 100 and 600, the said hydroxyl resin being constituted by a condensate resulting from the reaction of formaldehyde with a ketone chosen in the group constituted by (a) ketones of the formula Z-CO-R in which Z represents an aromatic mono- or poly-cyclic radical and R represents an aliphatic monovalent radical containing 1 to 4 atoms of carbon, (b) non-substituted cyclohexanone and (c) cyclohexanones substituted with a radical R, such as defined above, the molar ratio formaldehyde/ketone being between 0.5 and 3.</p> |
