Reduced-VOC and non-VOC blowing agents for making expanded and extruded thermoplastic foams
View Patent ↗A blowing agent blend for making thermoplastic polymer foams includes methyl formate. The blowing agent blend can further comprise at least one co-blowing agent. The co-blowing agent is either a physical co-blowing agent (e.g. an inorganic agent, a hydrocarbon, a halogenated hydrocarbon, a hydrocarbon with polar, functional group(s), water or any combination thereof), or a chemical co-blowing agent, or combinations thereof. The thermoplastic polymer foam can be an alkenyl aromatic polymer foam, e.g. a polystyrene foam. The blowing agent blend includes methyl formate and one or more co-blowing agents. The methyl formate-based blowing agent blends produce dimensionally stable foams that have improved resistance to flame spread. A process for the preparation of such foams is also provided.
1. A thermoplastic polymer foam board prepared by a process comprising:
preparing an expandable polymeric formulation comprising an alkenyl aromatic polymer and a blowing agent blend comprising methyl formate, hydrocarbon, and 1,1,1,2-tetrafluoroethane (HFC-134a); and
expanding the formulation to form a substantially closed-cell, dimensionally stable foam board exhibiting improved resistance to flame spread.
2. The thermoplastic polymer foam board of claim 1 , wherein the thermoplastic polymer foam board has an R value of about 4 per inch or greater.
3. The thermoplastic polymer foam board of claim 1 , wherein the hydrocarbon contains two to five carbon atoms.
4. The thermoplastic polymer foam board of claim 3 , wherein the hydrocarbon contains five carbon atoms.
5. The thermoplastic polymer foam board of claim 4 , wherein the hydrocarbon is cyclopentane.
6. The thermoplastic polymer foam board of claim 1 , wherein the blowing agent blend comprises about 23 to about 31 weight percent of methyl formate.
7. The thermoplastic polymer foam board of claim 1 , wherein the blowing agent blend comprises about 19 to about 24 weight percent of the hydrocarbon.
8. The thermoplastic polymer foam board of claim 1 , wherein the blowing agent blend comprises about 49 to about 53 weight percent of 1,1,1,2-tetrafluoro ethane (HFC-134a).
9. The thermoplastic polymer foam board of claim 1 , wherein the blowing agent blend comprises about 23 to about 31 weight percent of methyl formate, about 19 to about 24 weight percent of the hydrocarbon, and about 49 to about 53 weight percent of 1,1,1,2-tetrafluoroethane (HFC-134a).
10. A thermoplastic polymer foam board prepared by a process comprising:
preparing an expandable polymeric formulation comprising an amorphous polymer selected from the group consisting of polystyrene, polycarbonate, poly(methyl methacrylate), poly(phenylene oxide), and mixtures thereof and a blowing agent blend comprising methyl formate, hydrocarbon, and 1,1,1,2-tetrafluoroethane (HFC-134a); and
expanding the formulation to form a substantially closed-cell, dimensionally stable foam board exhibiting improved resistance to flame spread.
11. The thermoplastic polymer foam board of claim 1 , wherein the thermoplastic polymer foam board has a substantially uniform density.
12. The thermoplastic polymer foam board of claim 1 , wherein the thermoplastic polymer foam board has a density of about 1 lb/ft 3 to about 15 lb/ft 3 .
13. The thermoplastic polymer foam board of claim 1 , wherein the thermoplastic polymer foam board has a burn rate of less than about 30 inch/min.
14. A process for producing a thermoplastic polymer foam board comprising:
preparing an expandable polymeric formulation comprising an amorphous polymer selected from the group consisting of polystyrene, polycarbonate, poly(methyl methacrylate), poly(phenylene oxide), and mixtures thereof and a blowing agent blend comprising methyl formate, hydrocarbon, and 1,1,1,2-tetrafluoroethane (HFC-134a); and
expanding the formulation to form a substantially closed-cell, dimensionally stable foam board exhibiting improved resistance to flame spread.
15. The process of claim 14 , wherein preparing the expandable polymeric formulation comprises:
melting the thermoplastic polymer; and
dissolving an effective amount of the blowing agent blend in the thermoplastic polymer to define the formulation.
16. The process of claim 14 , wherein the thermoplastic polymer foam board has an R value of about 4 per inch or greater.
17. The process of claim 14 , wherein the hydrocarbon contains two to five carbon atoms.
18. The process of claim 17 , wherein the hydrocarbon contains five carbon atoms.
19. The process of claim 18 , wherein the hydrocarbon is cyclopentane.
20. The process of claim 14 , wherein the blowing agent blend comprises about 23 to about 31 weight percent of methyl formate.
21. The process of claim 14 , wherein the blowing agent blend comprises about 19 to about 24 weight percent of the hydrocarbon.
22. The process of claim 14 , wherein the blowing agent blend comprises about 49 to about 53 weight percent of 1,1,1,2-tetrafluoroethane (HFC-134a).
23. The process of claim 14 , wherein the blowing agent blend comprises about 23 to about 31 weight percent of methyl formate, about 19 to about 24 weight percent of the hydrocarbon, and about 49 to about 53 weight percent of 1,1,1,2-tetrafluoroethane (HFC-134a).
24. The process of claim 14 , wherein the thermoplastic polymer foam board has a substantially uniform density.
25. The process of claim 14 , wherein the thermoplastic polymer foam board has a density of about 1 lb/ft 3 to about 15 lb/ft 3 .
26. The process of claim 14 , wherein the thermoplastic polymer foam board has a burn rate of less than about 30 inch/min.
27. The thermoplastic polymer foam board of claim 1 , wherein the blowing agent blend comprises about 1 to about 99 weight percent of methyl formate.
28. The thermoplastic polymer foam board of claim 1 , wherein the blowing agent blend comprises about 20 to about 85 weight percent of methyl formate.
29. The process of claim 14 , wherein the blowing agent blend comprises about 1 to about 99 weight percent of methyl formate.
30. The process of claim 14 , wherein the blowing agent blend comprises about 20 to about 85 weight percent of methyl formate.