Patent ID: 7790778

Claim:
A process for preparing a flexible polyurethane foam, comprising: a pour-in-place-process reaction of a composition in a mould, the composition comprising: a polyisocyanate composition comprising: 1-99 parts by weight of an isocyanate-terminated prepolymer having an NCO-value of 5-30% by weight and being the reaction product of: an excessive amount of diphenylmethane diisocyanate comprising at least 80% by weight of 4,4′-diphenylmethane diisocyanate, and a first polyoxyethylene-polyoxypropylene polyol having an average molecular weight of 2000-10000, an average nominal hydroxy functionality of 2-6, an oxyethylene content of 21-45% by weight and from two to six -PO-PO/EO-EO tail structures connected to an initiator, wherein each structure linked to said initiator is a -PO-PO/EO-EO structure consisting of a first block of PO that is attached to the initiator, the first block comprises 60-90% of the PO, a second block of randomly distributed PO and EO connected to the PO block, and a third block of EO connected to the block of randomly distributed PO and EO that is the terminus of the -PO-PO/EO-EO structure, the ratio of third block EO to random EO being 3:1 to 1:3; and 1-99 parts by weight of an other polyisocyanate, calculated on 100 parts by weight of the polyisocyanate composition; 30-100 parts by weight of a second polyoxyethylene-polyoxypropylene polyol having an average nominal hydroxyl functionality of 2-6 and an oxyethylene (EO) content of more than 50% by weight; 0-70 parts by weight of a third polyoxyethylene-polyoxypropylene polyol having an average nominal hydroxy functionality of 2-6, an EO content of between 20-50% by weight and a primary hydroxyl content of at least 50%, calculated on the number of primary and secondary hydroxyl groups therein, and wherein the amounts of the second polyoxyethylene-polyoxypropylene polyol and the third polyoxyethylene-polyoxypropylene polyol being calculated on 100 parts by weight of the second polyoxyethylene-polyoxypropylene polyol and the third polyoxyethylene-polyoxypropylene polyol; and a blowing agent comprising water, wherein the mould has a foam barrier disposed on an outer layer and there is an absence of penetration of the outer layer by the flexible polyurethane foam.