Adhesive compositions and methods
The present invention encompasses polyurethane adhesive compositions comprising aliphatic polycarbonate chains. In one aspect, the present invention encompasses polyurethane adhesives derived from aliphatic polycarbonate polyols and polyisocyanates wherein the polyol chains contain a primary repeating unit having a structure:. In another aspect, the invention provides articles comprising the inventive polyurethane compositions as well as methods of making such compositions.
1. A reactive polyurethane adhesive formulation comprising segments derived from one or more aliphatic polycarbonate polyols having a structure P1:
wherein
R 1 , R 2 , R 3 , and R 4 are, at each occurrence in the polymer chain, independently selected from the group consisting of —H, fluorine, an optionally substituted C 1-40 aliphatic group, an optionally substituted C 1-20 heteroaliphatic group, and an optionally substituted aryl group;
any two or more of R 1 , R 2 , R 3 , and R 4 may optionally be taken together with intervening atoms to form one or more optionally substituted rings optionally containing one or more heteroatoms;
Y is, at each occurrence, independently —H, a reactive group, or a site of attachment to a chain-extending moiety;
is a multivalent moiety;
x and y are each independently an integer from 0 to 6, where the sum of x and y is between 2 and 6;
n is, at each occurrence independently, an integer from 3 to 1,000; and
wherein the strength of a cured bond formed by the polyurethane adhesive composition between two substrates is at least 30% greater at a temperature of 70° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C., wherein the strength is measured at each temperature by ASTM D1002 lap sheer test, and the strength is indicated by a measurement selected from the group consisting of: Load at Failure; Tensile Energy to Break; Stress at Yield; and Strain at Yield.
2. The polyurethane adhesive composition of claim 1 , wherein the strength of the cured bond formed by the polyurethane adhesive composition at is at least 40% greater at 70° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
3. The polyurethane adhesive composition of claim 2 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 50% greater at 70° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
4. The polyurethane adhesive composition of claim 3 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 75% greater at 70° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
5. The polyurethane adhesive composition of claim 4 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 100% greater at 70° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
6. The polyurethane adhesive composition of claim 5 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is between 100% and 200% greater at 70° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
7. The reactive polyurethane adhesive formulation of claim 1 , wherein at least one of Load at Failure, Tensile Energy to Break, or Strain at Yield is higher at 50° C. than at room temperature.
8. The polyurethane adhesive composition of claim 1 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 15% greater at 50° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
9. The polyurethane adhesive composition of claim 8 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 20% greater at 50° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
10. The polyurethane adhesive composition of claim 9 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 30% greater at 50° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
11. The polyurethane adhesive composition of claim 10 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 40% greater at 50° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
12. The polyurethane adhesive composition of claim 11 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 50% greater at 50° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
13. The polyurethane adhesive composition of claim 12 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 75% greater at 50° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
14. The polyurethane adhesive composition of claim 13 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is at least 100% greater at 50° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
15. The polyurethane adhesive composition of claim 14 , wherein the strength of the cured bond formed by the polyurethane adhesive composition is between 100% and 200% greater at 50° C. than the strength of the cured bond formed by the polyurethane adhesive composition at 25° C.
16. The reactive polyurethane adhesive formulation of claim 1 , wherein the cured bond formed by reactive polyurethane adhesive formulation retains at least 50% of its room temperature strength when heated to a temperature of 60° C.
17. The reactive polyurethane adhesive formulation of claim 1 characterized in that a cured sample of the reactive polyurethane adhesive formulation gains less than 5% mass upon immersion in toluene for 1 week at room temperature, or characterized in that a cured sample of the reactive polyurethane adhesive formulation gains less than 1% mass upon immersion in xylene for 1 week room temperature.
18. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols are characterized in that at least 99%, at least 99.5%, at least 99.7%, or at least 99.8% of the end groups are —OH groups.
19. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols comprise a copolymer of carbon dioxide and ethylene oxide.
20. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols comprise a copolymer of carbon dioxide and propylene oxide.
21. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols comprise a terpolymer of carbon dioxide and ethylene oxide along with one or more additional epoxides selected from the group consisting of propylene oxide, 1,2-butene oxide, 2,3-butene oxide, cyclohexene oxide, 3-vinyl cyclohexene oxide, epichlorohydrin, glicydyl esters, glycidyl ethers, styrene oxides, and epoxides of higher alpha olefins.
22. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols comprise a terpolymer of carbon dioxide and propylene oxide along with one or more additional epoxides selected from the group consisting of ethylene oxide, 1,2-butene oxide, 2,3-butene oxide, cyclohexene oxide, 3-vinyl cyclohexene oxide, epichlorohydrin, glicydyl esters, glycidyl ethers, styrene oxides, and epoxides of higher alpha olefins.
23. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols have a number average molecular weight (M n ) in the range of about 500 g/mol to about 10,000 g/mol, or between about 500 g/mol and about 5,000 g/mol, or between about 500 g/mol and about 4,000 g/mol, or between about 500 g/mol and about 3,000 g/mol, or between about 500 g/mol and about 2,500 g/mol, or between about 500 g/mol and about 1,500 g/mol.
24. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols are characterized in that, on average in the one or more aliphatic polyols, the percentage of carbonate linkages is 95% or greater or is 99% or greater.
25. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols are characterized in that, on average in the one or more aliphatic polyols, the percentage of carbonate linkages is 99% or greater.
26. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols are derived from a polyfunctional chain transfer agent having a formula:
27. The reactive polyurethane adhesive formulation of claim 26 , wherein
is derived from a dihydric alcohol.
28. The reactive polyurethane adhesive formulation of claim 26 , wherein y is 0 and x is greater than 2.
29. The reactive polyurethane adhesive formulation of claim 1 , wherein the one or more aliphatic polycarbonate polyols are selected from the group consisting of:
wherein, t is an integer from 1 to 12 inclusive, and R t is independently at each occurrence —H, or —CH 3 .
30. The reactive polyurethane adhesive formulation of claim 1 , comprising 100 parts by weight of a polyol component, wherein the one or more aliphatic polycarbonate polyols comprise from about 5 parts to 100 parts of the polyol component.
31. The reactive polyurethane adhesive formulation of claim 30 , further comprising 0.01 to 20 parts by weight of one or more chain extenders.
32. The reactive polyurethane adhesive formulation of claim 30 , further comprising 0 to 20 parts by weight of one or more reactive small molecules, wherein the one or more reactive small molecules comprise functional groups selected from the group consisting of hydroxyls, amines, thiols, and carboxylic acids.
33. The reactive polyurethane adhesive formulation of claim 32 , wherein the one or more reactive small molecule comprises a diol.
34. The reactive polyurethane adhesive formulation of claim 30 , further comprising 0 to 10 parts by weight of one or more additives, wherein the one or more additives are selected from the group consisting of: fillers, clays, blocking agents, stabilizers, thixotropic materials, plasticizers, compatibilizers, colorants, UV stabilizers or flame retardants.
35. The reactive polyurethane adhesive formulation of claim 1 , wherein the reactive polyurethane adhesive formulation is a one part adhesive formulation.
36. A method of joining two substrates, the method comprising the step of applying a reactive polyurethane adhesive formulation of claim 1 to at least one substrate, arranging the substrates so that both substrates are in contact with the reactive polyurethane adhesive formulation, and curing the reactive polyurethane adhesive formulation.