Foams based on thermoplastic polyurethanes
Expandable thermoplastic polyurethane comprising blowing agent, wherein the Shore hardness of the thermoplastic polyurethane is from A 44 to A 84.
1. An article of footwear comprising:
a sole comprising a plurality of fused expanded thermoplastic polyurethane beads.
2. The article of footwear of claim 1 , wherein the sole comprises a midsole.
3. The article of footwear of claim 1 , wherein the sole comprises an insole.
4. The article of footwear of claim 1 , wherein the expanded thermoplastic polyurethane beads form the entire sole.
5. The article of footwear of claim 1 , wherein the expanded thermoplastic polyurethane beads are based on a polyether alcohol.
6. The article of footwear of claim 1 , wherein the expanded thermoplastic polyurethane beads are based on a polyester alcohol.
7. The article of footwear of claim 1 , wherein the sole comprises a density between 8 g/l and 600 g/l.
8. The article of footwear of claim 1 , wherein the expanded thermoplastic polyurethane beads have a diameter between 0.2 mm and 20 mm.
9. The article of footwear of claim 8 , wherein the diameter is between 0.5 mm and 15 mm.
10. The article of footwear of claim 8 , wherein the diameter is between 1 mm and 12 mm.
11. The article of footwear of claim 1 , wherein the expanded thermoplastic polyurethane beads are spherical.
12. The article of footwear of claim 1 , wherein the expanded thermoplastic polyurethane beads are cylindrical.
13. The article of footwear of claim 1 , wherein the expanded thermoplastic polyurethane beads are elongate.
14. A sole for an article of footwear, the sole comprising:
a plurality of fused expanded thermoplastic polyurethane beads.
15. The sole of claim 14 , wherein the sole is a midsole.
16. The sole of claim 15 , wherein the midsole consists of the plurality of fused expanded thermoplastic polyurethane beads.
17. The sole of claim 15 , wherein the plurality of fused expanded thermoplastic polyurethane beads forms the entire midsole.
18. The sole of claim 14 , wherein the sole is an insole.
19. The sole of claim 14 , wherein the plurality of fused expanded thermoplastic polyurethane beads has a density between 8 g/l and 600 g/l.
20. A method of making a sole for an article of footwear, the method comprising:
impregnating thermoplastic polyurethane pellets with a blowing agent to form expandable thermoplastic polyurethane beads;
expanding the thermoplastic polyurethane beads; and
fusing the expanded thermoplastic polyurethane beads to one another to form the sole.
21. The method of claim 20 , wherein fusing the expanded thermoplastic polyurethane beads to one another to form the sole comprises placing the expanded thermoplastic polyurethane beads in a closed mold and exposing the expanded thermoplastic polyurethane beads to heat.
22. The method of claim 21 , wherein exposing the expanded thermoplastic polyurethane beads to heat comprises exposing the expanded thermoplastic polyurethane beads to a temperature between 100° C. and 140° C.
23. The method of claim 21 , wherein exposing the expanded thermoplastic polyurethane beads to heat comprises exposing the expanded thermoplastic polyurethane beads to steam at a temperature between 100° C. and 140° C.
24. The method of claim 20 , wherein the expanded thermoplastic polyurethane beads have a density between 5 g/l and 600 g/l.
25. The method of claim 20 , wherein the expanded thermoplastic polyurethane beads have a density between 10 g/l and 300 g/l.
26. The method of claim 20 , wherein the expanded thermoplastic polyurethane beads have a diameter between 1 mm and 12 mm.
27. The method of claim 20 , wherein the blowing agent comprises between 0.1% and 40% of the total weight of the pellets.