Process for preparing a flexible polyurethane foam by reacting a polyisocyanate and two different polyols under foam forming conditions so as to prepare a rigid foam and by crushing the rigid foam so obtained. Flexible foams are obtained which do not show a major glass transition temperature between -100.degree. C. and +25.degree. C.

Proceso para preparar una espuma flexible del poliuretano reaccionando un polyisocyanate y dos diversos polyols debajo de la espuma que forma condiciones para preparar una espuma rígida y machacando la espuma rígida obtuviera tan. Flexible hace espuma se obtienen que no demuestran una temperatura de transición de cristal importante entre -100.degree. C. y +25.degree. C.