| abstract |
The present invention concerns a rigid foam or composition allowing a rigid foam to be obtained made from polyurethane and/or polyisocyanurate, said foam or composition comprising polyols selected from polyester polyols and polyether polyols; said polyols comprising: 5 to 50% of a polyester polyol A by weight relative to the total weight of the polyols; and a polyol B selected from polyester polyols B and polyether polyols B. The polyester polyol A is of general formula Rx-Ry-Z-Ry'-Rx' in which Z is a C3 to C8 alcohol sugar chosen from glycerol, sorbitol, erythritol, xylitol, araditol, ribitol, dulcitol, mannitol and volemitol. Ry and Ry' are diesters of formula -OOC-Cn-COO- in which n is between 2 and 34, and Rx and Rx' are identical or different C2 to C12 monoalcohols. |