Epoxy Resin Adhesives

20250066650

18/710446

November 18, 2022

A curable epoxy resin adhesive, comprising an epoxy resin component and a curing agent component in a separated form, the epoxy resin component comprises at least one epoxide-containing resin, the curing agent component comprises: (i) a first amine curing agent comprising a polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2 where R is an aliphatic or cycloaliphatic constituent, unsubstituted or substituted with at least one functional group, Z is an oxyalkylene moiety and x has a value of greater than 1 and less than 10; and (ii) a second amine curing agent having the formula NH2—R1—NH2 where R1 is any aromatic constituent, unsubstituted or substituted with at least one functional group, wherein the curing agent component comprises from greater than 50 to up to 85 wt % of the first amine curing agent and from 15 to less than 50 wt % of the second amine curing agent, each based on the total weight of the first and second amine curing agents.

1. A curable epoxy resin adhesive, the adhesive comprising an epoxy resin component and a curing agent component, wherein the epoxy resin component and the curing agent component are in a separated form, and wherein providing a mixture of the epoxy resin component and the curing agent component at a curing temperature of the adhesive causes curing of the epoxy resin component by the curing agent component, wherein the epoxy resin component comprises at least one epoxide-containing resin, and wherein the curing agent component comprises: (i) a first amine curing agent, wherein the first amine curing agent comprises a polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2 where R is an aliphatic or cycloaliphatic constituent, which is either unsubstituted or substituted with at least one functional group, Z is an oxyalkylene moiety and x has a value of greater than 1 and less than 10; and (ii) a second amine curing agent having the formula NH2—R1—NH2 where R1 is any aromatic constituent, which is either unsubstituted or substituted with at least one functional group, wherein the curing agent component comprises from greater than 50 to up to 85 wt % of the first amine curing agent and from 15 to less than 50 wt % of the second amine curing agent, each based on the total weight of the first and second amine curing agents.

2. A curable epoxy resin adhesive according to claim 1 wherein the first amine curing agent has a first amine functionality corresponding to an active hydrogen equivalent weight (AHEW) of from 50-75 and the second amine curing agent has a second amine functionality which corresponds to an active hydrogen equivalent weight (AHEW) of from 15-45.

3. A curable epoxy resin adhesive according to claim 1 wherein in the first amine curing agent which comprises the polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2, Z is an oxypropylene moiety.

4. A curable epoxy resin adhesive according to claim 1 wherein in the first amine curing agent which comprises the polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2, x has a value within the range of from 2 to 5.

5. A curable epoxy resin adhesive according to claim 1 wherein in the first amine curing agent which comprises the polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2, R is an alkyl moiety having from 2 to 5 carbon atoms.

6. A curable epoxy resin adhesive according to claim 1 wherein in the first amine curing agent which comprises the polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2, Z is an oxypropylene moiety, x has a value within the range of from 2 to 3, and R is a propyl moiety having 3 carbon atoms.

7. A curable epoxy resin adhesive according to claim 1 wherein the polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2 has a number average molecular weight Mn of from 175 to 300.

8. A curable epoxy resin adhesive according to claim 7 wherein the polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2 has a number average molecular weight Mn of about 230.

9. A curable epoxy resin adhesive according to claim 1 wherein the first amine curing agent consists of the polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2.

10. A curable epoxy resin adhesive according to claim 1 wherein the second amine curing agent comprises di(aminoalkyl) benzene, wherein each alkyl group has from 1 to 3 carbon atoms and the alkyl groups are the same or different in each aminoalkyl functional group.

11. A curable epoxy resin adhesive according to claim 1 wherein the second amine curing agent comprises xylylenediamine, such as 1,3-Bis(aminomethyl)benzene (m-xylylenediamine) or 1,4-Bis(aminomethyl)benzene (p-xylylenediamine), 1,3-Bis(aminoethyl)benzene, 1,4-Bis(aminoethyl)benzene, 1,3-Bis(aminopropyl)benzene or 1,4-Bis(aminopropyl)benzene, or any mixture of two or more thereof.

12. A curable epoxy resin adhesive according to claim 10 wherein the second amine curing agent consists of one or more di(aminoalkyl) benzenes.

13. A curable epoxy resin adhesive according to claim 10 wherein the curing agent component comprises or consists of the polyoxyalkylene diamine having the formula NH2—(Z)x-R—NH2, in which Z is an oxypropylene moiety, x has a value within the range of from 2 to 5, and R is an alkyl moiety having from 2 to 5 carbon atoms, as the first amine curing agent, and 1,3-Bis(aminomethyl)benzene (m-xylylenediamine) and/or 1,4-Bis(aminomethyl)benzene (p-xylylenediamine), as the second amine curing agent.

14. A curable epoxy resin adhesive according to claim 1 wherein the curing agent component comprises from 60 to 75 wt % of the first amine curing agent and from 25 to 40 wt % of the second amine curing agent, each based on the total weight of the first and second curing agents.

15. A curable epoxy resin adhesive according to claim 1 wherein the curable epoxy resin adhesive exhibits a peak exotherm temperature within the range of from 200 to 230° C., when a 10 mL sample of the curable epoxy resin adhesive is cured in air at a curing temperature of 70° C.

16. A curable epoxy resin adhesive according to claim 15 wherein the curable epoxy resin adhesive exhibits a peak exotherm temperature within the range of from 210 to 220° C., when a 10 mL sample of the curable epoxy resin adhesive is cured in air at a curing temperature of 70° C.

17. A curable epoxy resin adhesive according to claim 1 wherein the curable epoxy resin adhesive exhibits a time period P1 from initiation of curing to peak exotherm temperature of from 1000 to 1500 seconds, measured when the curing is carried out in air at a curing temperature of 70° C. and on a resin sample having a volume of 10 mL.

18. A curable epoxy resin adhesive according to claim 17 wherein the curable epoxy resin adhesive exhibits a time period P1 from initiation of curing to peak exotherm temperature of from 1200 to 1350 seconds, measured when the curing is carried out in air at a curing temperature of 70° C. and on a resin sample having a volume of 10 mL.

19. A curable epoxy resin adhesive according to claim 1 wherein the curable epoxy resin adhesive exhibits a time period P2 from initiation of curing to peak exotherm temperature of from 7000 to 9000 seconds, measured when the curing is carried out in air at a curing temperature of 40° C. and on a resin sample having a volume of 10 mL.

20. A curable epoxy resin adhesive according to claim 19 wherein the curable epoxy resin adhesive exhibits a time period P2 from initiation of curing to peak exotherm temperature of from 7500 to 8500 seconds, measured when the curing is carried out in air at a curing temperature of 40° C. and on a resin sample having a volume of 10 mL.

21. A curable epoxy resin adhesive according to claim 1 wherein the weight ratio of the first amine curing agent to the second amine curing agent is within the range of from 1.8:1 to 2.4:1.

22. A curable epoxy resin adhesive according to claim 21 wherein the weight ratio of the first amine curing agent to the second amine curing agent is within the range of from 2.0:1 to 2.3:1.

23. A curable epoxy resin adhesive according to claim 1 wherein the curing agent component comprises from 5 to 8 wt % of the first amine curing agent and from 2 to 4 wt % of the second amine curing agent, each based on the total weight of the curing agent component.

24. A curable epoxy resin adhesive according to claim 23 wherein the curing agent component comprises from 6 to 7 wt % of the first amine curing agent and from 2.5 to 3.5 wt % of the second amine curing agent, each based on the total weight of the curing agent component.

25. A curable epoxy resin adhesive according to claim 1 wherein the curable epoxy resin adhesive, which comprises both the epoxy resin component and the curing agent component, comprises from 6.4 to 6.8 wt % of the first amine curing agent and from 2.9 to 3.3 wt % of the second amine curing agent, each based on the total weight of the curable epoxy resin adhesive.

26. A curable epoxy resin adhesive according to claim 1 wherein the epoxy resin component comprises a diglycidyl ether bisphenol-A (DGEBA) epoxy resin.

27. A curable epoxy resin adhesive according to claim 26 wherein the diglycidyl ether bisphenol-A (DGEBA) epoxy resin is liquid at 25° C. and has an epoxy equivalent weight (EEW) within the range of from 175 to 200 g/eq.

28. A method of manufacturing a curable epoxy resin adhesive according to claim 1, the method comprising the steps of: i. providing the epoxy resin component; ii. providing the first amine curing agent; iii. providing the second amine curing agent; iv. mixing together the first and second amine curing agents to produce the curing agent component; and v. providing both the epoxy resin component and the curing agent component in a separated form thereby to provide the curable epoxy resin adhesive, wherein providing a mixture of the epoxy resin component and the curing agent component at a curing temperature of the adhesive causes curing of the epoxy resin component by the curing agent component.

29. Use of the curable epoxy resin adhesive according to claim 1 for bonding together structural parts of a wind turbine blade, a marine vessel or a civil engineering structure.

09; 08; 08; 08; 08; 09

edspap.20250066650