Foam materials

• US 6,656,974 B1
• Filed: 09/21/2000
• Issued: 12/02/2003
• Est. Priority Date: 10/17/1997
• Status: Expired due to Fees

• Current Assignee: Advanced Medical Solutions (Europe) Ltd. (Advanced Medical Solutions Group Plc)
• Original Assignee: Advanced Medical Solutions (Europe) Ltd. (Advanced Medical Solutions Group Plc)
• Inventors: Renn, Donald W., Qin, Yimin, Rossetto, Chiara
• Primary Examiner(s): Lovering, Richard D.
• Application Number:
  US09/529,563
• Time in Patent Office: 1,167 Days
• Field of Search: 516/10, 516/11, 516/18, 516/19, 516/105, 516/106, 424/78.06, 514/945, 514/779
• US Class Current: 516/11
• CPC Class Codes: A61L 15/28 Polysaccharides or their derivatives A61L15/225 takes precedence
• CPC Class Codes: A61L 15/425 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: C08J 2305/04 Alginic acid; Derivatives thereof
• CPC Class Codes: C08J 9/125 Water, e.g. hydrated salts
• CPC Class Codes: C08L 5/04 Alginic acid; Derivatives thereof
• CPC Class Codes: Y10T 428/249964 Fibers of defined composition

Abstract

An absorbent foam material which comprises a solid, cross-linked form of an anionic polymer (e.g. an alginate) and fibers or other cation contributing polymeric particulates which have donated appropriate cations for effecting cross-linking of the anionic polymer. Methods of producing the foam material are also disclosed.

Claims

1. A method of producing an absorbent foam material suitable for use as a wound dressing, the method comprising generating a precursor foam comprised of a solution of an anionic alginate polymer in a solvent therefor and being further comprised of calcium/sodium alginate fibres or other calcium/sodium alginate particulate material, said fibres or other particulate material being capable of donating calcium cations for effecting cross-linking of the anionic alginate polymer, and effecting cross-linking of the anionic alginate polymer by said calcium cations from the fibres or other particulate material so as to convert the anionic alginate polymer into a solid form thereby providing said absorbent foam material wherein the fibres or other particulate material comprise 60 to 85% of the alginic acid in the form of the calcium salt with the remainder being in the form of the sodium salt.

2. A method as claimed in claim 1 further comprises an anionic polymer selected from the group consisting of:

low-methoxyl pectins, carrageenans, chrondoitin sulphate, hyaluronic acid, carboxymethyl cellulose, carboxymethyl starch, carboxymethyl guar, cellulose sulphate, dextran sulphate, gellan, xanthan, polyacrylic acid, a nucleic acid, and anionic derivatives of other hydrocolloids.

3. A method as claimed in claim 1 comprising preparing a solution of the anionic alginate polymer containing said calcium/sodium alginate fibres or other calcium/sodium alginate particulate material and effecting foaming of said solution to produce said precursor foam.

4. A method as claimed in claim 1 wherein the anionic alginate polymer has a molecular weight of 200,000 to 1,000,000.

5. A method as claimed in claim 4 wherein the anionic alginate polymer is one having a viscosity of 600-800 cP for a 1% solution thereof.

6. A method as claimed in claim 4 wherein the anionic alginate polymer has a G-content of 30-70% by mole and a M-content of 70−

30% by mole.

7. A method as claimed in claim 6 wherein the anionic alginate polymer has a G-content of about 40% by mole and a M-content of about 60% by mole.

8. A method as claimed in claim 1 wherein the calcium/sodium alginate fibres or other calcium/sodium alginate particulate material have a G-content of about 40% and M-content of about 60%.

9. A method as claimed in claim 1 wherein said precursor foam is generated with the aid of a foaming agent.

10. A method as claimed in claim 9 wherein the foaming agent is a cellulose derivative.

11. A method as claimed in claim 10 wherein the foaming agent is hydroxypropyl cellulose.

12. A method as claimed in claim 1 wherein the foam produced has a thickness of 1 to 5 mm.

13. A method as claimed in claim 1 wherein the foam produced incorporates at least one of a hydrophilic polymer to improve absorbency, a bulking/bodying agent, a humectant/plasticiser, a wound healing agent or other therapeutic or physiologically active substance, a soluble hydrocolloid, a salt and a sugar.

14. A method as claimed in claim 13 wherein the foam produced incorporates glycerol as a plasticiser.

15. A method as claimed in claim 1 wherein the foam produced incorporates activated charcoal.