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.

1 . A process for producing polyurethane wound dressing foams comprising frothing and drying of a polyurethane foam forming composition, wherein said polyurethane foam forming composition comprises (I) at least one aqueous, anionically hydrophilicized polyurethane dispersion, and (II) at least one cationic coagulant.  
   
   
       2 . The process of  claim 1 , wherein (I) said aqueous, anionically hydrophilicized polyurethane dispersion comprises the reaction product of: 
 A) one or more isocyanate-functional prepolymers which comprises the reaction product of: 
 A1) at least one organic polyisocyanate,  
 with  
 A2) at least one polymeric polyols having a number-average molecular weight in the range from 400 to 8000 g/mol and an OH functionality in the range from 1.5 to 6,  
 and  
 A3) optionally, one or more hydroxyl-functional compounds having molecular weights in the range from 62 to 399 g/mol,  
 and  
 A4) optionally, one or more isocyanate-reactive, anionic or potentially anionic and optionally nonionic hydrophilicizing agents;  
   with    B) one or more compounds selected from the group consisting of: 
 B1) optionally, one or more amino-functional compounds having molecular weights in the range from 32 to 400 g/mol,  
 and  
 B2) one or more amino-functional, anionic or potentially anionic hydrophilicizing agents;  
 in which the free NCO groups of A) are reacted in whole or in part with chain extension, and in which the prepolymers are dispersed in water either before, during or after the reaction with component B), and with any potentially ionic groups present being converted into the ionic form by partial or complete reaction with a neutralizing agent.  
   
   
   
       3 . The process according to  claim 2 , wherein component A1) said organic polyisocyanate is selected from the group consisting of 1,6-hexamethylene diisocyanate, isophorone diisocyanate, the isomeric bis(4,4′-isocyanatocyclohexyl)methanes and mixtures thereof, and component A2) said polymeric polyol comprises at least 70% by weight, based on 100% by weight of A2), of a mixture comprising one or more polycarbonate polyols and one or more polytetramethylene glycol polyols.  
   
   
       4 . The process according to any one of  claim 1 , in which component (II) said cationic coagulant comprises an acrylamide copolymer which comprises structural units of the general formulae (1) and (2):  
     
       
         
         
             
             
         
       
       wherein in Formula (2): 
 R: represents C═O, —COO(CH 2 ) 2 — or —COO(CH 2 ) 3 —; and  
 X − : represents a halide ion.  
 
     
   
   
       5 . The process of  claim 1 , additionally comprising (III) one or more auxiliary agents and/or additive materials.  
   
   
       6 . The process of  claim 5 , in which (III) said auxiliary agents and/or additive materials comprise foam formers and stabilizers which are selected from the group consisting of fatty acid amides, sulfosuccinamides, hydrocarbyl sulfonates, hydrocarbyl sulfates, fatty acid salts and/or alkylpolyglycosides.  
   
   
       7 . The process of  claim 6 , in which the foam formers comprise mixtures of sulfosuccinamides and ammonium stearates, with the mixtures containing from 50 to 70% by weight of sulfosuccinamides.  
   
   
       8 . Polyurethane wound dressing foams produced by the process of  claim 1 .  
   
   
       9 . The polyurethane wound dressing foams of  claim 8 , in which the polyurethane foam is characterized by a microporous, open-cell structure and a density of less than 0.4 g/cm 3  in the dried state.  
   
   
       10 . The polyurethane wound dressing foams of  claim 8 , wherein the polyurethane foams have a physiological saline absorbency of 100 to 1500% (mass of liquid taken up, based on the mass of dry foam) and a water vapor transmission rate in the range from 2000 to 8000 g/24 h*m 2 .  
   
   
       11 . Polyurethane foam forming compositions comprising (I) at least one aqueous, anionically hydrophilicized polyurethane dispersion, and (II) at least one cationic coagulant.