Polymer polyols comprising a natural oil base polyol, polyurethane foams comprising these polymer polyols and processes for their preparation

A process for the preparation of a polyurethane foam comprising reacting

• (I) at least one polyisocyanate component,
• with
• (II) at least one isocyanate-reactive component which comprises a polymer polyol which comprises the free-radical polymerization reaction product of:
• (1) a base polyol selected from the group consisting of:
• (c) one or more polyols which comprise the alkoxylation product of one or more natural oils which naturally contains at least one hydroxyl group with one or more alkylene oxides,
• (d) one or more polyols which comprise the alkoxylation product of one or more hydroxylated derivatives of one or more natural oils with one or more alkylene oxides;
• and
• (e) mixtures thereof;
• (2) at least one ethylenically unsaturated monomer,
• and
• (3) a preformed stabilizer,
• in the presence of
• (4) a free-radical polymerization initiator,
• and, optionally,
• (5) a chain transfer agent,
• wherein said polyol (1)(c) and polyol (1)(d) are alkoxylation products prepared in the presence of a double metal cyanide (DMC) catalyst,
• in the presence of
• (III) at least one blowing agent,
• and
• (IV) at least one catalyst;
• wherein said foam is a flexible foam having an elongation of at least 50%.