Curable epoxy resin composition

1. A method of producing a replenished curable epoxy resin composition, the method comprising: providing fresh resin having an inherent viscosity within the range of 80 mPas to 300 mPas measured at 50° C. to a curable epoxy resin composition in a pot at a temperature range of 40° C. to 70° C., by resin replenishment at a rate within the range of 10% to 30% of fresh resin per week, calculated to the total amount of resin present in the pot;

wherein the fresh resin is a resin that has not been previously added to the pot;

wherein the fresh resin and the curable epoxy resin composition in the pot comprise an aromatic epoxy resin component, a latent catalyst system, and optional additives;

wherein the replenished curable epoxy resin composition is a volatile-free single epoxy resin composition having a prolonged pot life at a processing temperature within the range of 40° C. to 70° C.; and

wherein:

(a) the aromatic epoxy resin component is a compound of formula (I) in monomeric form or in polymeric form thereof, or as a mixture thereof:

said aromatic epoxy resin component having an inherent viscosity within the range of 80 mPas to 300 mPas, measured at a temperature of 50° C.;

(b) the latent catalyst system comprises at least one metal acetylacetonate and at least one phenolic compound, wherein

(b1) the at least one metal acetylacetonate is present in a concentration of 0.1 phr to 1.0 phr (parts per hundred parts) of the epoxy resin component; and

(b2) the at least one phenolic compound is a dihydroxybenzene, a trihydroxybenzene or a mixture thereof, and is present in a concentration of 0.5 phr to 6.0 phr (parts per hundred parts) of the epoxy resin component.

2. The method according to claim 1 , wherein said curable epoxy resin composition in the pot has a pot life of at least one week, at an elevated processing temperature within the range of about 40° C. to 70° C., which can be prolonged for several more weeks by resin replenishment at a rate of resin replenishment within the range of 10% to 30% of fresh resin per week, calculated to the total amount of resin present in the pot.

3. The method according to claim 1 , wherein said curable epoxy resin composition in the pot has a pot life of at least three weeks, at an elevated processing temperature at about 50° C., which can be prolonged for several more weeks by resin replenishment at a rate of resin replenishment of 20% of fresh resin per week, calculated to the total amount of resin present in the pot.

4. The method according to claim 1 , wherein the fresh resin has an inherent viscosity within the range of about 80 mPas to about 120 mPas, measured at 50° C.

5. The method according to claim 1 , wherein the fresh resin has an inherent viscosity within the range of about 100 mPas to about 110 mPas, measured at 50° C.

6. The method according to claim 1 , wherein the viscosity of the replenished curable epoxy resin composition reached within the pot is within the range of about 260 mPas to about 300 mPas, measured at 50° C.

7. The method according to claim 1 , wherein the viscosity of the replenished curable epoxy resin composition reached within the pot is within the range of about 270 mPas to about 280 mPas, measured at 50° C.

8. The method according to claim 1 , wherein the resin replenishment is 20% of fresh resin per week, calculated to the total amount of resin present in the pot.

9. The method according to claim 1 , wherein the fresh resin has an inherent viscosity within the range of about 100 mPas to about 110 mPas, measured at 50° C., and the replenishment rate is 20% of fresh resin per week, calculated to the total amount of resin present in the pot.

10. The method according to claim 1 , wherein the aromatic epoxy resin component is based on a compound of formula (I):

and is present in monomeric form or low polymeric form or as a mixture thereof.

11. The method according to claim 10 , wherein the aromatic epoxy resin component is diglycidylether of bisphenol A, diglycidylether of bisphenol F, diglycidylether bisphenol S or a mixture thereof.

12. The method according to claim 11 , wherein the aromatic epoxy resin component has a molecular weight between 200 and 1200 and an epoxy value (equiv./kg) of at least three.

13. The method according to claim 10 , wherein the aromatic epoxy resin component is diglycidylether of bisphenol A, diglycidylether of bisphenol F or a mixture thereof.

14. The method according to claim 13 , wherein the aromatic epoxy resin component has a molecular weight between 200 and 1000 and an epoxy value (equiv./kg) of about 5.0 to 6.5.

15. The method according to claim 1 , wherein the at least one metal acetylacetonate corresponds to at least one of the chemical formulae (II), (III), (IV) and (V):

[CH 3 —C(O)—CH═C(O − )—CH 3 ].Me +   (II)

[CH 3 —C(O)—CH═C(O − )—CH 3 ] 2 .Me 2+   (III)

[CH 3 —C(O)—CH═C(O)—CH 3 ] 3 .Me 3+   (IV)

[CH 3 —C(O)—CH═C(O)—CH 3 ] 4 .Me 4+   (V),

wherein Me + is selected from the group consisting of Li + , Na + and K + ; Me 2+ is selected from the group consisting of Cu 2+ , Co 2+ , Zn 2+ and Ca 2+ ; Me 3+ is selected from the group consisting of Al 3+ , V 3+ and Fe 3+ ; and Me 4+ is Zr 4+ .

16. The method according to claim 15 , wherein Me 2+ is Mg 2+ , and Me 3+ is selected from the group consisting of Al 3+ and Fe 3+ .

17. The method according to claim 15 , wherein the at least one metal acetylacetonate is aluminum acetylacetonate, zirconium acetylacetonate or a mixture thereof.

18. The method according to claim 15 , wherein the at least one metal acetylacetonate is present in a concentration of 0.5 phr to 1.0 phr (parts per hundred parts) of the aromatic epoxy resin component.

19. The method according to claim 1 , wherein the at least one phenolic compound is selected from 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), 1,4-dihydroxybenzene (hydroquinone), 1,2,3-trihydroxybenzene (pyrogallol), 1,2,4-trihydroxybenzene and mixtures thereof.

20. The method according to claim 1 , wherein the at least one phenolic compound is catechol, resorcinol, hydroquinone or a mixture thereof.

21. The method according to claim 1 , wherein the at least one phenolic compound is present in a concentration of 2.0 phr to 4.0 phr, (parts per hundred parts) of the aromatic epoxy resin component.

22. The method according to claim 1 , wherein the ratio of the at least one metal acetylacetonate compound to the at least one phenolic compound is within the weight ratio of 4.0:1.0 to 1.0:1.0.

23. The method according to claim 1 , wherein the ratio of the at least one metal acetylacetonate compound to the at least one phenolic compound is within the weight ratio of 3.0:1.0 to 1.0:1.0.

24. The method according to claim 1 , wherein the optional additives are present and selected from the group consisting of filler materials, wetting/dispersing agents, plasticizers, antioxidants, and light absorbers.