Thermally protective materials
View Patent ↗A mixture comprising an expandable graphite and a polymer resin is described wherein the polymer resin-expandable graphite mixture has a volume increase and structural integrity after exposure to heat. Methods are described for increasing the thermal protective performance (TPP) of textiles and laminates while optionally maintaining comfort, flexibility, and liquid protective properties.
1. A method for increasing the thermal protective performance (TPP) of a thermally protective laminate compared to the laminate without an active insulation, said method comprising:
attaching a first convective barrier to a flame resistant, thermally stable textile;
applying an active insulation comprising a polymer resin-expandable graphite mixture on said first convective barrier on a side opposing said flame resistant, thermally stable textile;
positioning a second convective barrier on said polymer resin-expandable graphite mixture opposing said first convective barrier such that said polymer resin-expandable graphite mixture is sandwiched between said first and second convective barriers; and
positioning a backer textile on said active insulation to form a thermally protective laminate;
wherein said polymer resin-expandable graphite mixture comprises:
about 2 wt % to about 30 wt % of an expandable graphite; and
about 30 wt % to about 98 wt % of a polymer resin with a storage modulus between 10 3 and 10 6 dynes/cm 2 at 200° C. and Tan Delta of between 0.1 and 10 at 200° C.
2. The method of claim 1 , further comprising orienting said thermally protective laminate such that said flame resistant, thermally stable textile is subjected to a heat source when tested for TPP.
3. The method of claim 1 , wherein said first convective barrier comprises expanded polytetrafluoroethylene or polytetrafluoroethylene.
4. The method of claim 1 , wherein the thermal protective performance is increased by at least 2.0 cal/cm 2 per approximately 35 gsm of said polymer resin-expandable graphite mixture.
5. The method of claim 1 , wherein said active insulation is discontinuously applied to said first convective barrier.
6. The method of claim 1 , wherein said active insulation is positioned away from a heat source when said laminate is tested for TPP.
7. The method of claim 1 , wherein said thermally protective laminate has a CLO value less than about 0.45.
8. The method of claim 1 , wherein the TPP of the laminate is increased without substantially increasing the CLO value of the laminate.
9. The method of claim 1 , wherein less that 140 gsm of said polymer resin-expandable graphite mixture is applied to said first convective barrier.
10. The method of claim 1 , wherein after exposure to 300° C. for 90 seconds the expanded mixture maintains integrity upon thickness testing.
11. The method of claim 1 , wherein said polymer resin-expandable graphite mixture is elastic.
12. The method of claim 1 , wherein after exposure to 300° C. for 90 seconds the mixture comprises a plurality of tendrils comprising expanded graphite having an aspect ratio of at least 5 to 1.
13. The method of claim 1 , wherein said polymer resin-expandable graphite mixture has a minimum volume increase of at least 200% after exposure to 300° C. for 90 seconds.
14. The method of claim 1 , wherein said polymer resin of said polymer resin-expandable graphite mixture comprises polyurethane.
15. The method of claim 1 , wherein the flame resistant, thermally stable textile comprises PBI, PBO, modacrylic, FR cotton, FR rayon and blends thereof.
16. The method of claim 1 , further comprising the step of forming said polymer resin-expandable graphite mixture by melting or dissolving a polymer resin and mixing an expandable graphite in the melted or dissolved polymer resin.
17. The method of claim 1 wherein said polymer resin-expandable graphite mixture is applied as dots with approximately 2000 microns or greater spacing between dots.
18. A method for increasing the thermal protective performance (TPP) of a thermally protective laminate compared to the laminate without an active insulation, said method comprising:
forming an active insulation on a first convective barrier by discontinuously applying a polymer resin-expandable graphite mixture to a surface of said first convective barrier;
positioning a second convective barrier on said polymer resin-expandable graphite mixture opposing said first convective barrier such that said polymer resin-expandable graphite mixture is sandwiched between said first and second convective barriers; and
positioning a flame resistant, thermally stable textile on said first convective barrier on a side opposite said polymer resin-expandable graphite mixture to form a thermally protective laminate,
wherein said polymer resin-expandable graphite mixture comprises:
about 2 wt % to about 30 wt % of an expandable graphite; and
about 30 wt % to about 98 wt % of a polymer resin with a storage modulus between 10 3 and 10 6 dynes/cm 2 at 200° C. and Tan Delta of between 0.1 and 10 at 200° C.
19. The method of claim 18 , further comprising orienting said thermally protective laminate such that said flame resistant, thermally stable textile is subjected to a flame and said active insulation is positioned away from said heat source.
20. The method of claim 18 , wherein the thermal protective performance is increased by at least 2.0 cal/cm 2 per approximately 35 gsm of said polymer resin-expandable graphite mixture.
21. The method of claim 18 , wherein said thermally protective laminate has a CLO value less than about 0.45.
22. The method of claim 18 , wherein the TPP of the laminate is increased without substantially increasing the CLO value of the laminate.
23. The method of claim 18 , wherein said first convective barrier comprises expanded polytetrafluoroethylene or polytetrafluoroethylene.
24. The method of claim 18 , wherein the thermal protective performance is increased by at least 2.0 cal/cm 2 per approximately 35 gsm of said polymer resin-expandable graphite mixture.
25. The method of claim 18 , wherein said thermally protective laminate has a CLO value less than about 0.45.
26. The method of claim 18 , wherein the TPP of the laminate is increased without substantially increasing the CLO value of the laminate.
27. The method of claim 18 , wherein after exposure to 300° C. for 90 seconds the expanded mixture maintains integrity upon thickness testing.
28. The method of claim 18 , wherein after exposure to 300° C. for 90 seconds the mixture comprises a plurality of tendrils comprising expanded graphite having an aspect ratio of at least 5 to 1.
29. The method of claim 18 , wherein said polymer resin-expandable graphite mixture has a minimum volume increase of at least 200% after exposure to 300° C. for 90 seconds.
30. The method of claim 18 , wherein the flame resistant, thermally stable textile comprises PBI, PBO, modacrylic, FR cotton, FR rayon and blends thereof.
31. The method of claim 18 , further comprising the step of forming the polymer resin-expandable graphite mixture by melting or dissolving a polymer resin and mixing an expandable graphite in the melted or dissolved polymer resin.
32. The method of claim 18 , wherein less that 140 gsm of said polymer resin-expandable graphite mixture is applied to said first convective barrier.
33. The method of claim 18 , wherein said polymer resin-expandable graphite mixture is elastic.
34. The method of claim 18 , wherein said polymer resin of said polymer resin-expandable graphite mixture comprises polyurethane.
35. The method of claim 18 , wherein said polymer resin-expandable graphite mixture is applied as dots with approximately 2000 microns or greater between said dots.
36. The method of claim 18 , wherein said active insulation is discontinuously applied to said first convective barrier.
37. The method of claim 18 , wherein said active insulation is positioned away from a heat source when said laminate is tested for TPP.