Polyurethane foams for wound management

Abstract

The invention relates to a process for producing polyurethane foams for wound management. These polyurethane wound dressing foams are prepared by a process comprising frothing and drying of a foam foaming composition, which comprises a polyurethane dispersion and specific coagulants.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATION [0001] The present patent application claims the right of priority under 35 U.S.C. §119 (a)-(d) of German Patent Application No. 10 2006 016 636.1, filed on Apr. 8, 2006. BACKGROUND OF THE INVENTION [0002] The present invention relates to a process for producing polyurethane wound dressing foams comprising polyurethane wound dressing foams foams which are frothed and dried, in which the polyurethane foams comprise one or more polyurethane dispersions and one or more coagulants. [0003] Polyurethane wound dressing foams are known to be suitable for treating exsudating wounds. Due 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. Numerous forms of these processes for ...

AI Technical Summary

Benefits of technology

[0008] It has now been found that polyurethane foam forming compositions containing polyurethane dispersions and specific cationic coagulants, both free of isocyanate groups, can be used to produce at ambient conditions polyurethane foams having good mechanical properties, a high absorbence of physiological saline and a high water and moisture vapour transmission rate. The polyurethane foams exhibit, at least to some extent, an open-cell pore structure. The flowable polyurethane foam forming compositions, moreover, can be applied directly to the skin by spraying or casting.

[0010] For purposes of the present invention, polyurethane wound dressing foams are porous materials, preferably having at least some open-cell content, which are made of polyurethanes. These materials protect wounds against germs and environmental influences like a sterile covering, and they have a fast and high absorbence of physiological saline (i.e. more precisely wound fluid), a suitable permeability for moisture to ensure a suitable wound climate, and sufficient mechanical strength.

Problems solved by technology

The aforementioned processes, however, have the disadvantage that they require the use of reactive mixtures which contain diisocyanates or corresponding NCO-functional prepolymers, the handling of which is technically inconvenient and costly due to the necessary appropriate protective measures associated with such diisocyanates or NCO-functional prepolymers of these diisocyanates.

Polyaziridines are no longer acceptable, however, because of their toxicity.

The foams produced according to the processes described in EP 0 235 949 and EP 0 246 723, moreover, have the immense disadvantage that the foams obtained therein are only minimally open-cell, which reduces the absorbance of physiological saline and also the water or moisture vapor transmission rate.

The management of wounds having a complex topology or the coverage of particularly deep wounds is difficult with ready-to-use, industrially manufactured sheetlike polyurethane wound dressing foams, since optimal covering of the wound surface is generally not accomplished, thus retarding the healing process.

However, this also does not achieve optimal covering of the wound.

The two processes described above, which utilize either diisocyanates / NCO-functional polyurethane prepolymers or polyurethane dispersions in combination with polyaziridines to produce polyurethane foams, cannot be used for this.

Also, polyurethane dispersions which contain polyaziridines as crosslinkers are not acceptable because this crosslinker has properties which are not generally recognized as safe by toxicologists.

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