Patent ID: 6884825

Claim:
A process for preparing a flexible polyurethane foam comprising reacting at an isocyanate index of 70 to 130: 1) 40-65 parts by weight of a polyisocyanate composition comprising: a) 80-100% by weight of a diphenylmethane diisocyanate component comprising, based on 100 parts by weight of the diphenylmethane diisocyanate component: i) 75 to 100 parts by weight of diphenylmethane diisocyanate comprising 15-75 parts by weight of 4,4′-diphenylmethane diisocyanate, and 25 to 85 parts by weight of 2,4′-diphenylmethane diisocyanate, and 2,2′-diphenylmethane diisocyanate and/or a liquid variant of such diphenylmethane diisocyanate, and ii) 0 to 25 parts by weight of homologues of diphenylmethane diisocyanates having an isocyanate functionality of 3 or more; and b) 20-0% by weight of toluene diisocyanate; 2) 20 to 45 parts by weight of a polyether polyol having an average molecular weight of 4500-10000, an average nominal functionality of 2-6 and comprising oxypropylene and optionally oxyethylene groups, the amount of oxypropylene groups being at least 70% by weight calculated on the weight of this polyol; 3) 3 to 20 parts by weight of a polyether polyol having an average molecular weight of 700-4000, an average nominal functionality of 2-6 and an hydroxyl value of at most 225 mg KOH/g and comprising oxyethylene and optionally oxypropylene groups, the amount of oxyethylene groups being at least 70% by weight calculated on the weight of this polyol; and 4) 2-6 parts by weight of water, wherein, the amount of the polyisocyanate composition, the polyether polyol 2), the polyether polyol 3), and water being 100 parts by weight.