Silicone wound dressing laminate and method for making the same

Abstract

A method of making a wound dressing comprising the steps of: providing an apertured substrate layer; coating the substrate layer with a fluid silicone prepolymer composition; thermally partially curing said silicone prepolymer composition to form a partially cured silicone coating on the substrate; laminating the coated substrate layer to a base layer to form a laminate having said partially cured silicone coating in contact with a surface of the base layer; followed by exposing the laminate to ionizing radiation, to further cure the partially cured silicone coating and to bond the silicone coating to said surface of the base layer. The radiation cure results in strong bonding between the siliconized substrate and incompatible base layers such as polyurethane foams. Also provided are wound dressings obtainable by the process of the invention.

1 . A wound dressing comprising:
 an absorbent polyurethane base layer;   an apertured substrate; and   a silicone coating on the apertured substrate;   wherein
 the silicone coating on the apertured substrate is covalently bonded to the absorbent polyurethane base layer; and 
 the silicone coating comprises
 (a) a polydiorganosiloxane comprising at least two alkenyl groups; and 
 (b) a polydiorganosiloxane comprising at least two silicon-bonded hydrogen atoms. 
 
   
     
     
         2 . The wound dressing of  claim 1 , wherein the polydiorganosiloxane comprising at least two alkenyl groups comprises a polydimethylsiloxane, a dimethylsiloxane-methylvinylsiloxane copolymer, a dimethylsiloxane-methylphenylsiloxane copolymer, or a combination of any two or more thereof. 
     
     
         3 . The wound dressing of  claim 1 , wherein the polydiorganosiloxane comprising at least two silicon-bonded hydrogen atoms comprises a polydimethylsiloxane, a polymethylhydrogensiloxane, a dimethylsiloxane-methylhydrogensiloxane copolymer, a methylphenylsiloxane-methylhydrogensiloxane copolymer, or a combination of any two or more thereof. 
     
     
         4 . The wound dressing of  claim 1 , wherein a peel strength greater than 200 mN/cm is required to separate the silicone coated apertured substrate from the absorbent polyurethane base layer. 
     
     
         5 . The wound dressing of  claim 1 , wherein the absorbent polyurethane base layer is in the form of a polymeric film sheet, a foam, a sponge, or a film. 
     
     
         6 . The wound dressing of  claim 1 , wherein the absorbent polyurethane base layer to which the silicone coating is bonded is hydrophilic. 
     
     
         7 . The wound dressing of  claim 1 , wherein the absorbent polyurethane base layer is a semipermeable polyurethane film or a hydrophilic polyurethane foam sheet. 
     
     
         8 . The wound dressing of  claim 1 , wherein the apertured substrate is coated on both sides with the silicone coating, and a surface of the silicone coating opposite the absorbent polyurethane base layer is non-adherent or tacky. 
     
     
         9 . The wound dressing of  claim 1 , wherein the absorbent polyurethane base layer is further laminated to an adhesive-coated liquid-impermeable backing sheet. 
     
     
         10 . The wound dressing of  claim 9 , wherein the wound dressing is in the form of an island dressing wherein the adhesive-coated liquid-impermeable backing sheet is larger than the absorbent polyurethane base layer whereby a margin of the backing sheet extends around one or more edges of the absorbent polyurethane base layer. 
     
     
         11 . The wound dressing of  claim 1 , wherein the wound dressing is sterile and is packaged in a microorganism-impermeable container. 
     
     
         12 . The wound dressing of  claim 1 , wherein the silicone coating is coated on a first side and a second side of the apertured substrate, wherein the first side of the apertured substrate is adapted to be bonded to the surface of the absorbent polyurethane base layer, and wherein the second side of the apertured substrate coated with the silicone coating is substantially non-adherent. 
     
     
         13 . The wound dressing of  claim 1 , wherein the apertured substrate comprises a cellulose acetate gauze. 
     
     
         14 . The wound dressing of  claim 1 , wherein the wound dressing is sterilized by ionizing radiation. 
     
     
         15 . A method of making the wound dressing of  claim 1 , the method comprising the steps of:
 providing the apertured substrate layer;   coating the apertured substrate layer with a fluid silicone prepolymer composition;   thermally partially curing said silicone prepolymer composition to form a partially cured silicone coating on the apertured substrate layer;   laminating the coated apertured substrate layer to the absorbent polyurethane base layer to form a laminate having said partially cured silicone coating in contact with a surface of the absorbent polyurethane base layer; and   exposing the laminate to ionizing radiation, to further cure the partially cured silicone coating and to bond the silicone coating to said surface of the absorbent polyurethane base layer.   
     
     
         16 . The method of  claim 15 , wherein the silicone prepolymer composition comprises a polymerization inhibitor that is evaporated from said composition during said step of thermally partially curing. 
     
     
         17 . The method of  claim 15 , further comprising the step of packaging the laminate having said partially cured silicone coating in a microorganism-impermeable container prior to said step of exposing, and wherein said step of exposing also sterilizes said laminate. 
     
     
         18 . The method of  claim 15  wherein a peel strength greater than 200 mN/cm is required to separate the silicone coated apertured substrate from the absorbent polyurethane base layer. 
     
     
         19 . The method of  claim 15 , wherein the silicone coating is coated on a first side and a second side of the apertured substrate layer, wherein the first side of the apertured substrate layer is adapted to be bonded to the surface of the absorbent polyurethane base layer, and wherein the second side of the apertured substrate layer coated with the silicone coating is substantially non-adherent. 
     
     
         20 . The method of  claim 15 , wherein the absorbent polyurethane base layer is further laminated to an adhesive-coated liquid-impermeable backing sheet.