Epoxy systems for composites
Compositions and methods for forming epoxy resin systems are provided. In one embodiment, a composition is provided for an epoxy resin system including a reaction product of an epoxy resin component and a curing agent component comprising a first amine compound having the formula R1R2R3N, wherein R1 and R2 are independently an aliphatic or alicyclic organic functional group and R3 is an alkyl group, having a backbone of 2-18 carbon atoms, and a second amine compound having one or more primary or secondary amine groups, with the stoichiometic ratio of —NH bonds of the second amine compound to the epoxy groups of the epoxy resin component being from 1:20 to about 21:20. The composition may be used to form composites, such as used in commercial wind turbine blade manufacturing.
1. A composition comprising an epoxy resin system, the epoxy resin system comprising a reaction product of:
an epoxy resin component; and
a curing agent component comprising:
a first amine compound represented by the formula:
wherein R1 and R2 each comprise an organic functional group having from 1-6 carbon atoms, and R3 comprises an alkyl group, having a backbone of 8-18 carbon atoms selected from the group consisting of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and combinations thereof; and
a second amine compound having one or more primary amine groups, one or more secondary amine groups, or combinations thereof, wherein the stoichiometric ratio of the —NH bonds of the second amine compound to the epoxy groups of the epoxy resin component is from about 1:20 to about 21:20 and the molar ratio of the second amine compound to the first amine compound is from about 0.01:1 to about 100:1;
wherein the alkyl group of R3 further comprises a functional group selected from the group consisting of a primary amine group, a secondary amine group, a tertiary amine group, and combinations thereof, or R3 further comprises a functional group selected from the group consisting of an acrylate group, a methacrylate group, an acrylamide group, a methacrylamide group, and combinations thereof, or both.
2. The composition of claim 1 , wherein the second amine compound comprises one or more amine compounds selected from the group consisting of a polyether diamine, a saturated aliphatic ring diamine, a linear aliphatic amine, and combinations thereof.
3. The composition of claim 1 , wherein the stoichiometric ratio of the —NH bonds of the second amine compound to the epoxy groups of the epoxy resin component is up to 1:1.
4. The composition of claim 2 , wherein, the polyether diamine has the formula: H 2 NCH(CH 3 )CH 2 [OCH 2 CH(CH 3 )] X NH 2 , and x is from 2 to 70.
5. The composition of claim 1 , wherein the R3 comprises an 8-12 carbon atom alkyl group selected from the group consisting of a linear alkyl group, a branched alkyl group, a cyclic alkyl group, and combinations thereof.
6. The composition of claim 1 , wherein R1 and R2 each comprise a functional group selected from the group consisting of a methyl group, an ethyl group, a propyl group, a C5-C6 carbocyclic aliphatic ring, a C5-C6 heterocyclic aliphatic ring, a C5-C6 saturated aliphatic ring, a C5-C6 unsaturated aliphatic ring, and combinations thereof.
7. The composition of claim 6 , wherein R1 and R2 are both methyl functional groups.
8. The composition of claim 7 , wherein the second amine compound comprises a mixture of isophoronediamine and the polyetheramine H 2 NCH(CH 3 )CH 2 [OCH 2 CH(CH 3 )] 2.5 NH 2 .
9. The composition of claim 1 , wherein the epoxy resin component further comprises a polyglycidyl ether of a compound selected from the group consisting of an aliphatic glycol, a cycloaliphatic glycol, a triol, a polyol, a polyglycol, and combinations thereof.
10. The composition of claim 1 , wherein the epoxy resin system further comprises a polyacrylate or polymethacrylate ester of a polyol.
11. The composition of claim 1 , wherein, when cured, the reaction product of the epoxy resin component and the curing agent exhibits a T g of 75° C. or higher at a cure time of three hours or less as measured by Differential Scanning Calorimetry.
12. The composition of claim 1 , wherein, when curing, the reaction product of the epoxy resin component and the curing agent exhibits a maximum exothermic temperature of 230° C. or lower for a 100 gram mass in a water bath at 70° C.
13. The composition of claim 1 , wherein the curing agent further comprises a modified amine compound selected from the group consisting of a secondary amine Mannich base, an aminopolyamide compound, an amine-epoxy adduct, and combinations thereof.
14. A composite prepared using an epoxy resin composition of claim 1 .
15. The composite of claim 14 , wherein the composite of the epoxy resin component and the curing agent exhibits a T g of 75° C. or higher at a cure time of 3 hours or less as measured by Differential Scanning Calorimetry.
16. The composite of claim 14 , wherein the composite formed from the epoxy resin component and the curing agent exhibits a maximum exothermic temperature of 230° C. or lower during formation.
17. The composite of claim 14 , wherein the composite further includes a reinforcing fiber substrate.
18. The composite of claim 17 , wherein the reinforcing fiber substrate comprises about 70 wt. % continuous uni-directional fibers and about 30 wt % continuous +/−45° E-glass fibers.
19. The composite of claim 14 , wherein the composite is in the form of a windmill blade.