The use of wound dressing foams for managing weeping wounds is prior art. Owing to their high absorbency and their good mechanical properties, polyurethane foams produced by reaction of mixtures of diisocyanates and polyols or NCO-functional polyurethane prepolymers with water in the presence of certain catalysts and also (foam) additives are generally used. Aromatic diisocyanates are generally employed, since they are best foamable. Numerous forms of these processes are known, for example described in U.S. Pat. No. 3,978,266, U.S. Pat. No. 3,975,567 and EP-A 0 059 048. However, the aforementioned processes have the disadvantage that they require the use of reactive mixtures, comprising diisocyanates or appropriate NCO-functional prepolymers, whose handling is technically inconvenient and costly, since appropriate protective measures are necessary for example. Direct application of these mixtures to (human) skin is not possible because of the high reactivity of the isocyanate groups present.
As well as through the use of compositions comprising free isocyanate groups, polyurethane foams can also be produced using silane-terminated polyurethane prepolymers which are foamable through use of blowing agents. Numerous embodiments are known for producing sealing and insulating foams, for example described in EP-A 1 098 920. The use of the compositions for producing wound dressing foams was hitherto not recognized. Nor have the critical requirements for use as wound dressing foams, such as good water vapour permeability and high liquid uptake capacity, hitherto been described.
USPTO Backgrounds
USPTO Backgrounds