Color indicating epoxy resins and methods thereof

1. An epoxy composition comprising: a first component comprising an amine-based curing agent and a first dye, wherein the first component has a first color; and a second component comprising a curable epoxy resin and a second dye, wherein the second component has a second color, wherein at least one of the first dye or the second dye is selected from (i) a halochromic dye and (ii) a dye that undergoes a color change when combined with primary amines.

2. The composition according to claim 1 , wherein the first component and the second component are mixed to form a mixture and wherein the mixture has a third color.

3. The composition according to claim 2 , wherein the third color is visually not an additive of the first color and the second color.

4. The composition according to claim 2 , wherein the mixture is cured and the cured mixture has a fourth color.

5. The composition according to claim 4 , wherein the first color and the second color are visually different, wherein the third color is visually different from the first color and the second color, and wherein the fourth color is visually different in color from the first color, the second color, and the third color.

6. The composition according to claim 5 , wherein the difference in color has a ΔH of at least 1 when calculated in L*C*h color space.

7. The composition according to claim 5 , wherein the difference in color has a ΔE of at least 1 when calculated in L*a*b* color space.

8. The composition according to claim 1 wherein the first dye is at least one of a triarylmethane compound, an azo compound, and combinations thereof.

9. The composition according to claim 1 wherein the second dye is at least one of a triarylmethane compound, an azo compound, and combinations thereof.

10. The composition according to claim 1 wherein at least one of the first dye and the second dye is a cationic triarylmethane compound.

11. The composition according to claim 1 , wherein at least one of the first dye and the second dye is a halochromic dye, which comprises a color transition range from pH 7-9 in an aqueous solution.

12. The composition according to claim 1 ,wherein the first dye is selected from at least one of: Patent Blue V, and Bromothymol Blue.

13. The composition according to claim 1 , wherein the second dye is selected from at least one of: Cresol Red, Erichrome Black T, and Methyl Red.

14. The composition according to claim 1 , wherein the amine-based curing agent is selected from the formula:

R 1 R 2 N—R 3 —NR 4 H  (I)

wherein R 1 , R 2 and R 4 represent, independently from each other, hydrogen, a linear or branched alkyl or a linear or branched polyoxyalkyl moiety and R 3 represent a linear or branched alkyl, alkylamine, polyaminoalkyl, polyamidoalkyl, alkylether, or polyoxyalkyl residue having at least 5 carbon atoms.

15. A 2-component epoxy comprising:

a first component comprising an amine-based curing agent and a first halochromic dye, wherein the first halochromic dye has a first color transition range and a second component comprising a curable epoxy resin comprising a second halochromic dye and having a second color transition range.

16. The 2-component epoxy according to claim 15 , wherein at least one of the first color transition range or the second color transition range is between 7-9 when measured in an aqueous solution.

17. The 2-component epoxy according to claim 15 wherein at least one of the first halochromic dye and the second halochromic dye is at least one of Cresol Red, Erichrome Black T, Thymol Blue, Bromothymol Blue, and combinations thereof.