US Patent 6841586 Felted hydrophilic ester polyurethane foams

An ester polyurethane foam is prepared by reacting a mixture of one or more polyester polyols with one or more isocyanates and one or more silicone surfactants in the presence of a blowing agent, such as water, and other additives, such as catalysts. The cured foam is chemically treated in a caustic solution and is then felted (compressed under heat and pressure) to form a hydrophilic ester polyurethane foam having a water absorption rate of at least 30 pounds of water per square foot per minute (1.44 kPa/min). The foam also has greater water holding capacity and wet strength than cellulose.