Process for foaming thermoplastic elastomers

Patent metadata

Field	Value
Publication number	US-10005209-B2
Application number	US-201715609684-A
Country	US
Kind code	B2
Filing date	May 31, 2017
Priority date	Mar 15, 2013
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

A foamed article is made by infusing the article of thermoplastic elastomer with a supercritical fluid, then removing the article from the supercritical fluid and either (i) immersing the article in a heated fluid or (ii) irradiating the article with infrared or microwave radiation.

First claim

What is claimed is:

1. A method of foaming an article comprising a thermoplastic elastomer, comprising:
infusing a plurality of articles comprising a thermoplastic elastomer with a supercritical fluid, thereby forming a plurality of infused articles comprising the thermoplastic elastomer, wherein the thermoplastic elastomer is selected from the group consisting of thermoplastic polyurethane elastomers, thermoplastic polyurea elastomers, thermoplastic polyamide elastomers, and combinations thereof;
following the infusing, either:
(i) immersing the plurality of infused articles in a heated fluid, wherein, during the immersing, the heated fluid is at a temperature at least 80° C. higher than a glass transition temperature of the thermoplastic elastomer but less than a melting temperature of the thermoplastic elastomer; or
(ii) irradiating the plurality of infused articles with infrared or microwave radiation;
thereby foaming the plurality of infused articles and forming a plurality of foamed articles, wherein the foamed articles of the plurality are selected from foamed pellets, foamed beads, and foamed particles; and
molding together the plurality of foamed articles to form a midsole.

2. The method according to claim 1 , wherein the thermoplastic elastomer comprises a thermoplastic polyurethane elastomer.

3. The method according to claim 1 , wherein the plurality of articles have at least one dimension that is 10 mm or less.

4. The method according to claim 1 , wherein the plurality of infused articles are saturated with the supercritical fluid.

5. The method according to claim 1 , wherein the supercritical fluid comprises carbon dioxide.

6. The method according to claim 1 , wherein the supercritical fluid comprises nitrogen.

7. The method according to claim 1 , wherein the supercritical fluid comprises a polar fluid having a Hildebrand solubility parameter equal to or greater than 9 MPa −1/2 .

8. The method according to claim 1 , wherein the heated fluid is water.

9. The method according to claim 1 , wherein the method includes the step of irradiating the plurality of infused articles with infrared or microwave radiation.

10. The method according to claim 1 , wherein method further comprises annealing the plurality of foamed articles at a temperature below the melting temperature of the thermoplastic elastomer prior to the molding.

11. The method according to claim 1 , wherein the method further comprises coating the plurality of foamed articles with an adhesive before the molding.

12. The method according to claim 1 , wherein the plurality of foamed articles have a density from about 0.01 to about 0.3 g/cm 3 .

13. The method according to claim 1 , wherein the plurality of foamed articles are spherical or ellipsoidal.

14. The method according to claim 13 , wherein the plurality of foamed articles have a diameter of from about 0.5 mm to about 1.5 cm.

15. The method according to claim 13 , wherein the plurality of foamed articles are ellipsoidal and are from 2 mm to 20 mm in length.

16. The method according to claim 1 , wherein the thermoplastic elastomer is selected from the group consisting of thermoplastic polyurethane elastomers, thermoplastic polyurea elastomers, thermoplastic polyamide elastomers, metallocene-catalyzed block copolymer elastomers of ethylene and α-olefins having 4 to about 8 carbon atoms, styrene block copolymer elastomers, and combinations thereof.

17. A method of foaming an article comprising a thermoplastic elastomer, comprising:
infusing a plurality of articles comprising a thermoplastic elastomer with a supercritical fluid, thereby forming a plurality of infused articles comprising the thermoplastic elastomer;
following the infusing,
(i) immersing the plurality of infused articles in a heated fluid or
(ii) irradiating the plurality of infused articles with infrared or microwave radiation;
thereby foaming the infused articles and forming a plurality of foamed articles;
wherein the foamed articles of the plurality are selected from foamed pellets, foamed beads, and foamed particles;
annealing the plurality of foamed articles at a temperature below the elastomer's melting temperature; and
molding together the plurality of foamed articles to form a midsole.

18. The method according to claim 17 , wherein the thermoplastic elastomer is selected from the group consisting of thermoplastic polyurethane elastomers, thermoplastic polyurea elastomers, thermoplastic polyamide elastomers, metallocene-catalyzed block copolymer elastomers of ethylene and α-olefins having 4 to about 8 carbon atoms, styrene block copolymer elastomers, a combinations thereof.

19. The method according to claim 17 , wherein the thermoplastic elastomer comprises a thermoplastic polyurethane elastomer.

20. The method according to claim 17 , wherein the plurality of articles have at least one dimension that is 10 mm or less.

21. The method according to claim 17 , wherein the plurality of infused articles are saturated with the supercritical fluid.

22. The method according to claim 17 , wherein the supercritical fluid comprises carbon dioxide.

23. The method according to claim 17 , wherein the supercritical fluid comprises nitrogen.

24. The method according to claim 17 , wherein the supercritical fluid comprises a polar fluid having a Hildebrand solubility parameter equal to or greater than 9 MPa −1/2 .

25. The method according to claim 17 , wherein the method includes the step of immersing the plurality of infused articles in a heated fluid, and wherein the heated fluid is at a temperature that is at least about 80° C. higher than a glass transition temperature of the first thermoplastic elastomer but less than a melting temperature of the first thermoplastic elastomer.

26. The method according to claim 25 , wherein the heated fluid is water.

27. The method according to claim 17 , wherein method includes the step of irradiating the plurality of infused articles with infrared or microwave radiation.

28. The method according to claim 17 , wherein the method further comprises coating the plurality of foamed articles with an adhesive before the molding.

29. The method according to claim 18 , wherein the plurality of foamed articles have a density from about 0.01 to about 0.3 g/cm 3 .

30. The method according to claim 18 , wherein the plurality of foamed articles are spherical or ellipsoidal.

31. The method according to claim 30 , wherein the plurality of foamed articles have a diameter of from about 0.5 mm to about 1.5 cm.

32. The method according to claim 30 , wherein the plurality of foamed articles are ellipsoidal and are from 2 mm to 20 mm in length.

33. A method of foaming an article comprising a thermoplastic elastomer, comprising:
infusing a plurality of articles comprising a first thermoplastic elastomer with a supercritical fluid, thereby forming a plurality of infused articles comprising the first thermoplastic elastomer;
following the infusing, either:
(i) immersing the plurality of infused articles in a heated fluid, wherein, during the immersing, the heated fluid is at a temperature at least 80° C. higher than a glass transition temperature of the first thermoplastic elastomer but less than a melting temperature of the first thermoplastic elastomer; o

Assignees

• Nike Inc

Inventors

• Baghdadi Hossein A
• Chang Yihua
• Edwards Charles R
• Watkins Richard L

Classifications

• B29C44/3453

  Feeding the blowing agent to solid plastic material · CPC title

• C08J2203/06

  CO2, N2 or noble gases · CPC title

• C08J2300/22

  Thermoplastic resins · CPC title

• C08J2375/04

  Polyurethanes · CPC title

• A43B13/125

  characterised by the midsole or middle layer · CPC title