초록 ▼

The invention provides a method of forming a polyurethane foam suitable for use as a wound-contacting layer, said method comprising: mixing 1 part by weight of an isocyanate-capped prepolymer having from 0.5 to 4.8 meq. NCO groups/g with from 0.4 to 1.0 parts by weight of water and an effective amou

The invention provides a method of forming a polyurethane foam suitable for use as a wound-contacting layer, said method comprising: mixing 1 part by weight of an isocyanate-capped prepolymer having from 0.5 to 4.8 meq. NCO groups/g with from 0.4 to 1.0 parts by weight of water and an effective amount of a nonvolatile pharmaceutically acceptable acid to form a prepolymer mixture; allowing said prepolymer mixture to cure to form a foamed product; followed by drying the foamed product. The invention also provides acidified polyurethane foams obtainable by this method, and wound dressings comprising such foams.

대표청구항 ▼

1. A method of forming a polyurethane foam suitable for use as a wound-contacting layer, said method comprising mixing one part by weight of an isocyanate-capped prepolymer having from 0.5 to 4.8 meq NCO groups/gram with from 0.4 to 1.0 parts by weight of water, wherein said mixture further contains

1. A method of forming a polyurethane foam suitable for use as a wound-contacting layer, said method comprising mixing one part by weight of an isocyanate-capped prepolymer having from 0.5 to 4.8 meq NCO groups/gram with from 0.4 to 1.0 parts by weight of water, wherein said mixture further contains from 0.2 to 20% by weight of alginic acid or a salt thereof. 2. A method according to claim 1, wherein the isocyanate-capped prepolymer has from 0.5 to 1.2 meq NCO groups/gram. 3. A method according to claim 1, wherein the step of mixing is carried out in the presence of from 0.05 to 0.4 parts by weight of a C1to C3monohydric alcohol. 4. A method according to claim 3, wherein the monohydric alcohol is methanol. 5. A method according to claim 1, wherein the alginic acid salt is sodium alginate, calcium alginate, or a combination thereof. 6. A method according to claim 1, wherein said prepolymer mixture contains from 0.5 to 10% by weight of said alginic acid or salt thereof. 7. A method according to claim 1, wherein said isocyanate-capped prepolymer is an isocyanate-capped polyether prepolymer. 8. A method according to claim 7, wherein said isocyanate-capped polyether prepolymer is an isocyanate-capped ethyleneoxy/propyleneoxy copolymer. 9. A method according to claim 1 wherein one part by weight of the isocyanate-capped prepolymer is mixed with from 0.6 to 0.9 parts by weight water. 10. A method according to claim 3 wherein one part by weight of the isocyanate-capped prepolymer is mixed with water in the presence of from 0.05 to 0.25 parts by weight of methanol or from 0.1 to 0.3 parts by weight ethanol. 11. A polyurethane foam which is suitable for use as a wound-contacting layer, said foam having a density of at least 0.28 grams/centimeter3,and containing from 0.2 to 20% by weight of alginic acid or a pharmaceutically acceptable salt thereof, generally uniformly distributed throughout said foam. 12. A polyurethane foam according to claim 11, wherein said foam contains from 0.5 to 10% by weight of said alginic acid or salt thereof. 13. A polyurethane foam according to claim 11 having a density in the range of from 0.32 to 0.48 grams/centimeter3. 14. A polyurethane foam according to claim 11 having an elongation at break of at least 150%. 15. A polyurethane foam according to claim 14 having an elongation at break of from 500 to 2000%. 16. A polyurethane foam according to claim 11 having an absorbency of at least 10 grams saline/gram. 17. A polyurethane foam according to claim 11 having a swellability on absorption of water of at least 200% by volume. 18. A polyurethane foam according to claim 11, containing less than 0.01% by weight of water-soluble alcohols. 19. A polyurethane foam according to claim 11, wherein said alginic acid salt is sodium alginate, calcium alginate, or a combination thereof. 20. A wound dressing having a wound-contact layer formed from a polyurethane foam according to any one of claims 1 to 19.