Flexible polyurethane foams with high water absorption capacity

A process for producing a hydrophilic flexible polyurethane foam, comprising mixing

• (a) at least one polyurethane prepolymer (a) having an isocyanate content of 5 to 10% by weight, based on the weight of the at least one polyurethane prepolymer (a), and
• (b) at least one aqueous component (b)
• in a ratio by weight of the at least one polyurethane prepolymer (a) to the at least one aqueous component (b) from 3:1 to 1:1.2 and allowing the mixture to react to form the flexible polyurethane foam,
• wherein the at least one polyurethane prepolymer (a) is obtained by mixing and reacting at least one isocyanate (a1) with at least one polyetherol (a2),
• wherein:
• the at least one isocyanate (a1) comprises methylenediphenylene diisocyanate,
• the at least one polyetherol (a2) has a hydroxyl number of 30 to 60 mg KOH/g and an ethylene oxide content of at least 60% by weight, based on the total weight of ethylene oxide and propylene oxide used to prepare the at least one polyetherol (a2), the at least one difunctional and/or trifunctional starter molecule in a first step up to a hydroxyl number of 400 to 1200 mg KOH/g, followed by an alkoxylation of the propoxylated starter molecule with a mixture of ethylene oxide and propylene oxide and finally an ethoxylation of the alkoxylation product thus obtained with 2 to 10% by weight ethylene oxide, based on the alkylene oxide used for producing the at least one polyetherol (a2), and
• the at least one aqueous component (b) comprises at least 90% by weight water (b1) and up to 10% by weight non-silicone-containing surface-active substances (b2), based in each case on the total weight of the at least one aqueous component (b).