Patent ID: 11891471
Assignee: BASF SE
Field: Medical technology (Instruments)
Classification: CPC C  A | IPC A  C

Claim 0:
1. 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).