Process for the preparation of flexible, resilient polyurethane foam and the resulting foam

A process for the preparation of flexible polyurethane foam having a density of between 30 and 70 kg/m3, a resilience, measured in accordance with ASTM D 3574 H, higher than 40%, an ILD 40% hardness, measured in accordance with ISO 2439 B, of between 75 and 250 N, by reacting at least one polyisocyanate having at least two isocyanate groups with one or more liquid compounds which have at least two isocyanate reactive groups and at least one of which contain one or more solid polymers stably dispersed therein in an amount of 2.5 to 35 parts per 100 parts of said liquid isocyanate reactive groups containing compounds,

• wherein the wet compression set of the flexible polyurethane foam, measured in accordance with Renault 1637, is reduced to a value of less than 5% by including in said liquid isocyanate reactive groups containing compounds, per 100 parts thereof:
• a) 50 to 80 parts of one or more polyoxyalkylene polyols having an oxyethylene unit content of at least 60 wt. % of the oxyalkylene units of the polyoxyalkylene polyol, a hydroxyl number of between 20 and 100, and a nominal functionality of 2 to 4;
• b) 20 to 50 parts of one or more further polyoxyalkylene polyols containing no oxyethylene units or having an oxyethylene unit content lower than 40 wt. % of the oxyalkylene units of the further polyoxyalkylene polyol, and having a hydroxyl number of between 20 and 100, and a nominal functionality of 2 to 4.