Forming a chemically cross-linked particle of a desired shape and diameter

• US 7,053,134 B2
• Filed: 03/28/2003
• Issued: 05/30/2006
• Est. Priority Date: 04/04/2002
• Status: Expired due to Term

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Scimed Life Systems Incorporated (Boston Scientific Corporation)
• Inventors: Skribiski, Robert P., Baldwin, Samuel P.
• Primary Examiner(s): Seidleck, James J.
• Assistant Examiner(s): McClendon, Sanza L.
• Application Number:
  US10/402,068
• Publication Number:
  US 20030203985A1
• Time in Patent Office: 1,159 Days
• Field of Search: 522/87, 522/88, 522/90, 522/149, 522/150, 522/151, 522/153, 522/154, 522/157, 522/162, 522/166, 428/402, 264/429, 264/460, 264/461, 264/463, 264/478, 264/485, 264/488, 264/494, 264/496, 526/142, 526/200
• US Class Current: 522/154
• CPC Class Codes: A61F 2/0036 implantable A61F2/0018 takes precedence
• CPC Class Codes: A61L 24/001 Use of materials characterised by their function or physical properties
• CPC Class Codes: A61L 24/06 obtained by reactions only involving carbon-to-carbon unsaturated bonds A61L24/043, A61L24/046 take precedence
• CPC Class Codes: A61L 27/16 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 27/50 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61L 31/048 obtained by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: A61L 31/14 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: C08L 29/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

Chemically cross-linked polymeric particles are formed using mechanical rather than chemical processes, facilitating production of small-diameter particles in a manner largely independent of the viscosity or density of the polymer. For example, an uncross-linked resin may be provided in particulate form, agglomerated, and compressed into a mass of a desired shape with a desired diameter, and subsequently cross-linked.

Claims

1. A method of forming a chemically cross-linked particle, the method comprising:

providing an uncross-linked polyvinyl alcohol resin in particulate form;

agglomerating the resin into a mass;

compressing the mass into a sphere with a diameter of less than 600 microns; and

cross-linking the mass to thereby form the chemically cross-linked particle.

2. The method of claim 1 further comprising the step of adding a binding agent to the resin.

3. The method of claim 2 wherein the step of adding a binding agent comprises adding a starch.

4. The method of claim 2 wherein the step of adding a binding agent comprises adding a sugar.

5. The method of claim 1 wherein the step of cross-linking the mass comprises exposing the mass to actinic energy.

6. The method of claim 5 wherein the step of exposing the mass to actinic energy comprises exposing the mass to one of an electron beam, ultraviolet radiation, and gamma radiation.

7. The method of claim 1 wherein the step of cross-linking the mass comprises exposing the mass to a gaseous cross-linking agent.

8. The method of claim 2 further comprising the step of removing the binding agent by exposing the particle to a solvent formulated to selectively dissolve the binding agent.

9. A method of forming a chemically cross-linked particle, the method comprising:

providing an uncross-linked resin in particulate form;

adding a binding agent to the resin, the binding agent having a melting point below a melting point of the resin;

agglomerating the resin into a mass;

heating the mass to a temperature above the melting point of the binding agent and below the melting point of the resin;

compressing the mass into a sphere with a diameter of less than 600 microns;

cooling the mass to a temperature below the melting point of the binding agent; and

cross-linking the mass to thereby form the chemically cross-linked particle.

10. The method of claim 9 wherein the binding agent is a polymer, the polymer becoming part of the chemically cross-linked particle.

11. The method of claim 9 wherein the step of cross-linking the mass comprises exposing the mass to actinic energy.

12. The method of claim 11 wherein the step of exposing the mass to actinic energy comprises exposing the mass to one of an electron beam, ultraviolet radiation, and gamma radiation.

13. The method of claim 9 wherein the step of cross-linking the mass comprises exposing the mass to a gaseous cross-linking agent.

14. The method of claim 9 further comprising the step of removing the binding agent by heating the chemically cross-linked particle to a temperature above the melting point of the binding agent thereby melting the binding agent out of the chemically cross-linked particle.

15. The method of claim 9 further comprising the step of removing the binding agent by exposing the particle to a solvent formulated to selectively dissolve the binding agent.

16. A method of forming a chemically cross-linked spherical particle, the method comprising:

providing in particulate form an uncross-linked resin selected from the group consisting polyvinyl alcohol, polyvinyl acetate, vinyl polymers, polyamides, polyureas, and methacrylates;

agglomerating the resin into a mass;

compressing the mass into a sphere with a diameter of less than 600 microns; and

cross-linking the mass by exposing the mass to radiation, to thereby form the chemically cross-linked spherical particle.

17. The method of claim 16, further comprising the step of adding a binding agent to the resin, wherein the binding agent comprises sucrose.

18. The method of claim 17, further comprising the step of removing the binding agent by exposing the particle to a solvent formulated to selectively dissolve the binding agent.

19. The method of claim 16, further comprising the step of adding a binding agent to the resin, wherein the binding agent comprises a starch.

20. The method of claim 19, further comprising the step of removing the binding agent by exposing the particle to a solvent formulated to selectively dissolve the binding agent.

21. The method of claim 16, wherein the step of cross-linking the mass comprises exposing the mass to radiation selected from the group consisting of electron beam radiation, ultraviolet radiation, and gamma radiation.

22. The method of claim 16, wherein the step of cross-linking the mass comprises exposing the mass to formaldehyde or gluturaldehyde.

23. A method of forming a chemically cross-linked particle, the method comprising:

providing an uncross-linked resin in particulate form;

agglomerating the resin into a mass;

compressing the mass into a sphere with a diameter of less than 600 microns; and

exposing the mass to actinic energy to cross-link the mass to thereby form the chemically cross-linked particle.

24. The method of claim 23 further comprising the step of adding a binding agent to the resin.

25. The method of claim 24 wherein the step of adding a binding agent comprises adding a starch.

26. The method of claim 24 wherein the step of adding a binding agent comprises adding a sugar.

27. The method of claim 24 further comprising the step of removing the binding agent by exposing the particle to a solvent formulated to selectively dissolve the binding agent.

28. The method of claim 23 wherein the step of exposing the mass to actinic energy comprises exposing the mass to one of an electron beam, ultraviolet radiation, and gamma radiation.

29. The method of claim 23 wherein the resin comprises a polyvinyl alcohol resin.

30. A method of forming a chemically cross-linked particle, the method comprising:

providing an uncross-linked resin in particulate form;

agglomerating the resin into a mass;

compressing the mass into a sphere with a diameter of less than 600 microns; and

exposing the mass to a gaseous cross-linking agent to cross-link the mass to thereby form the chemically cross-linked particle.

31. The method of claim 30 further comprising the step of adding a binding agent to the resin.

32. The method of claim 31 wherein the step of adding a binding agent comprises adding a starch.

33. The method of claim 31 wherein the step of adding a binding agent comprises adding a sugar.

34. The method of claim 31 further comprising the step of removing the binding agent by exposing the particle to a solvent formulated to selectively dissolve the binding agent.

35. The method of claim 30 wherein the resin comprises a polyvinyl alcohol resin.

36. A method of forming a chemically cross-linked particle, the method comprising:

providing an uncross-linked resin in particulate form;

agglomerating the resin into a mass;

compressing the mass into a sphere with a diameter of less than 600 microns; and

cross-linking the mass to thereby form the chemically cross-linked particle.

37. The method of claim 36 further comprising the step of adding a binding agent to the resin.

38. The method of claim 37 wherein the step of adding a binding agent comprises adding a starch.

39. The method of claim 37 wherein the step of adding a binding agent comprises adding a sugar.

40. The method of claim 37 further comprising the step of removing the binding agent by exposing the particle to a solvent formulated to selectively dissolve the binding agent.

41. The method of claim 36 wherein the step of cross-linking the mass comprises exposing the mass to actinic energy.

42. The method of claim 41 wherein the step of exposing the mass to actinic energy comprises exposing the mass to one of an electron beam, ultraviolet radiation, and gamma radiation.

43. The method of claim 36 wherein the step of cross-linking the mass comprises exposing the mass to a gaseous cross-linking agent.