Wound covering and its method of production by extrusion coating
The invention relates to a production method for a foam wound dressing with an outer germ barrier, in particular a film layer, and to a wound dressing obtained by such a method. In the method according to the invention, the germ barrier is generated by means of extrusion directly on the foam support. This results in a more reliable union between foam layer and germ barrier, without thereby compromising the absorbency of the foam in respect of wound exudate. The proposed method is simple and inexpensive and is able to satisfy all the requirements of the medical sector (e.g. freedom from solvents).
1. A method of producing a substantially uninterrupted wound cover, said wound cover comprising
a first layer of a foam material, having a first main area and a second main area; and
a second layer of a film material as a germ barrier, which second layer is directly adjacent to the first main area of the first layer,
said method comprising steps of:
i) providing the foam material of the first layer;
ii) extruding at least one thermoplastic material onto a main area of the foam material at a temperature above the softening temperature of the thermo-plastic material, and solidifying the thermoplastic material to form the second layer, wherein the thermoplastic material of the second layer penetrates not more than 0.01 mm into the foam material of the first layer.
2. The method of claim 1 , wherein the foam material of the first layer is a polyurethane foam.
3. The method of claim 1 , wherein the first layer is hydrophilic.
4. The method of claim 1 wherein the foam material of the first layer is open-celled.
5. The method of claim 1 , wherein the at least one thermo-plastic material is extruded in step ii) onto the foam material in such a way as to form a second layer having a thickness between 15 μm to 100 μm.
6. The method of claim 1 , wherein the extrusion of the at least one thermoplastic material takes place in step ii) at a temperature in the range between 150° C. and 240° C.
7. The method of claim 1 , wherein two layers of thermoplastic material are produced during the extruding step.
8. The method of claim 1 , wherein the at least one thermoplastic material is foamed during said extruding step.
9. The method of claim 1 , wherein, after said extruding step, the thermoplastic material is pressed onto the first layer by a cooled roll.
10. The method of claim 1 , wherein a thermoplastic polyurethane material is used as the thermoplastic material in step ii).
11. The method of claim 1 , wherein the at least one thermoplastic material is foamed after said extruding step.
12. A substantially uninterrupted wound cover, said wound cover comprising
a first layer of a foam material, having a first main area and a second main area; and
a second layer of a thermoplastic film material as a germ barrier, which second layer is directly adjacent to the first main area of the first layer, and wherein the thermoplastic material of the second layer penetrates not more than 0.01 mm into the foam material of the first layer.
13. The wound cover of claim 12 , obtained by steps of
i) providing the foam material of the first layer; and
ii) extruding the at least one thermoplastic material onto the foam material at a temperature above the softening temperature of the thermo-plastic material, and solidifying the material to form the second layer, while limiting penetration of the thermoplastic material of the second layer into the foam material of the first layer to not more than 0.01 mm.