MICROENCAPSULATED PARTICLES AND PROCESS FOR MANUFACTURING SAME

• US 20040130045A1
• Filed: 11/14/2002
• Published: 07/08/2004
• Est. Priority Date: 11/20/2001
• Status: Active Grant

• Current Assignee: Robert G. Bayless
• Original Assignee: Robert G. Bayless
• Inventors: Bayless, Robert G.
• Granted Patent: US 6,833,191 B2
• Time in Patent Office: Days
• US Class Current: 264/4.3
• CPC Class Codes: B01J 13/06 by phase separation
• CPC Class Codes: B01J 13/14 Polymerisation; cross-linking
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2984 Microcapsule with fluid core [includes liposome]
• CPC Class Codes: Y10T 428/2985 Solid-walled microcapsule from synthetic polymer
• CPC Class Codes: Y10T 428/2989 Microcapsule with solid core [includes liposome]
• CPC Class Codes: Y10T 428/2991 Coated

Abstract

Microencapsulated particles having improved resistance to moisture and extended release capabilities are produced by microencapsulating the particles in a film-forming, cross-linked, hydrolyzed polymer.

Claims

1. A process for microencapsulating a substance, wherein the process comprises the steps of:

A. mixing a film-forming, cross-linkable, hydrolyzed polymer and an organic, nonpolar solvent for the polymer, wherein the solvent is not a solvent for particles of the substance;

B. agitating the mixture to form a solution of the polymer in the solvent;

C. adding particles of the substance to the solution under conditions of continuing agitation, wherein the substance particles are dispersed in the solution;

D. inducing a phase separation of the solution, wherein the polymer is separated from the solution and a film-like sheath of the polymer is formed and coated on each substance particle; and

E. adding a cross-linking agent to the solution under conditions of continuing agitation, wherein the film-like sheath on each substance particle cross-links and hardens around each substance particle,

whereby the microencapsulated substance particles have improved impermeability to moisture as compared to substance particles that are microencapsulated using other film-forming polymers.

2. A process as defined by claim 1 wherein the substance is a phosphor.

3. A process as defined by claim 1 wherein the substance is a polymer light-emitting diode.

4. A process as defined by claim 1 wherein the substance is an organic light-emitting diode.

5. A process as defined by claim 1 wherein the film-forming, cross-linkable, hydrolyzed polymer is a poly (ethylene-vinyl acetate).

6. A process as defined by claim 1 wherein the organic, nonpolar solvent is toluene.

7. A process as defined by claim 1 wherein the phase separation is induced by addition of cottonseed oil, corn oil, linseed oil, soybean oil or a mixture of two or more of these oils.

8. A process as defined by claim 1 wherein the cross-linking agent is a diisocyanate or polyisocyanate.

9. A process as defined by claim 8 wherein the cross-linking agent is toluene diisocyanate.

10. A process as defined by claim 8 wherein the cross-linking agent is a toluene diisocyanate-trimethyol propane adduct.

11. A process as defined by claim 1 wherein the polymer is hydrolyzed from about 42 to about 46 percent.

31. A process as defined by claim 1 wherein the steps are sequential.

12. A microencapsulated substance having improved impermeability to moisture, wherein the microencapsulated substance is produced by a process that comprises the steps of:

A. mixing a film-forming, cross-linkable, hydrolyzed polymer and an organic, nonpolar solvent for the polymer, wherein the solvent is not a solvent for particles of the substance;

B. agitating the mixture to form a solution of the polymer in the solvent;

C. adding particles of the substance to the solution under conditions of continuing agitation, wherein the substance particles are dispersed in the solution;

D. inducing a phase separation of the solution, wherein the polymer is separated from the solution and a film-like sheath of the polymer is formed and coated on each substance particle; and

E. adding a cross-linking agent to the solution under conditions of continuing agitation, wherein the film-like sheath on each substance particle cross-links and hardens around each substance particle,

whereby the microencapsulated substance particles have improved impermeability to moisture as compared to substance particles that are microencapsulated using other film-forming polymers.

13. A microencapsulated substance as defined by claim 12 wherein the film-forming, cross-linkable, hydrolyzed polymer is a poly (ethylene-vinyl acetate).

14. A microencapsulated substance as defined by claim 12 wherein the organic, nonpolar solvent is toluene.

15. A microencapsulated substance as defined by claim 12 wherein the phase separation is induced by addition of cottonseed oil, corn oil, linseed oil, soybean oil or a mixture of two or more of these oils.

16. A microencapsulated substance as defined by claim 12 wherein the cross-linking agent is a diisocyanate or polyisocyanate.

17. A microencapsulated substance as defined by claim 16 wherein the cross-linking agent is toluene diisocyanate.

18. A microencapsulated substance as defined by claim 16 wherein the cross-linking agent is a toluene diisocyanate-trimethyol propane adduct.

19. A microencapsulated substance as defined by claim 12 wherein the polymer is hydrolyzed from about 42 to about 46 percent.

21. A microencapsulated substance as defined by claim 12 wherein the substance is a polymer light-emitting diode.

22. A microencapsulated substance as defined by claim 12 wherein the substance is an organic light-emitting diode.

20. A microencapsulated substance as defined by claim 120 wherein the substance is a phosphor.

23. A process for microencapsulating phosphor particles, wherein the process comprises the steps of:

A. mixing a film-forming, cross-linkable, hydrolyzed polymer and an organic, nonpolar solvent for the polymer, wherein the solvent is not a solvent for particles of the substance;

B. agitating the mixture to form a solution of the polymer in the solvent;

C. adding particles of the substance to the solution under conditions of continuing agitation, wherein the substance particles are dispersed in the solution;

D. inducing a phase separation of the solution, wherein the polymer is separated from the solution and a film-like sheath of the polymer is formed and coated on each substance particle; and

E. adding a cross-linking agent to the solution under conditions of continuing agitation, wherein the film-like sheath on each substance particle cross-links and hardens around each substance particle,

whereby the microencapsulated substance particles have improved impermeability to moisture as compared to substance particles that are microencapsulated using other film-forming polymers.

24. A process as defined by claim 23 wherein the film-forming, cross-linkable, hydrolyzed polymer is a poly (ethylene-vinyl acetate).

25. A process as defined by claim 23 wherein the organic, nonpolar solvent is toluene.

26. A process as defined by claim 23 wherein the phase separation is induced by addition of cottonseed oil, corn oil, linseed oil, soybean oil or a mixture of two or more of these oils.

27. A process as defined by claim 23 wherein the cross-linking agent is a diisocyanate or polyisocyanate.

28. A process as defined by claim 27 wherein the cross-linking agent is toluene diisocyanate.

29. A process as defined by claim 27 wherein the cross-linking agent is a toluene diisocyanate-trimethyol propane adduct.

30. A process as defined by claim 23 wherein the polymer is hydrolyzed from about 42 to about 46 percent.

32. A process as defined by claim 23 wherein the microencapsulated phosphor particles are useful in electroluminescent applications.