Dual cure coating composition and processes for using the same

• US 20030078316A1
• Filed: 08/28/2001
• Published: 04/24/2003
• Est. Priority Date: 08/28/2001
• Status: Active Grant

• Current Assignee: BASF Corporation (BASF SE)
• Original Assignee: BASF Corporation (BASF SE)
• Inventors: Bradford, Christopher J., Caillouette, Lyle, Zimmer, Marcy, Rischke, Jennifer A., OʼDonnell, Ryan F.
• Granted Patent: US 6,835,759 B2
• Time in Patent Office: Days
• US Class Current: 522/126
• CPC Class Codes: C08G 18/792 formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
• CPC Class Codes: C08J 3/243 Two or more independent types of crosslinking for one or more polymers
• CPC Class Codes: C08L 75/04 Polyurethanes
• CPC Class Codes: C09D 175/16 having terminal carbon-to-carbon unsaturated bonds

Abstract

The coating composition comprises a radiation curable component (a1), a thermally curable binder component (a2), a thermally curable crosslinking component (a3), and optionally, one or more reactive diluents (a4). Radiation curable component (a1) is polymerizable upon exposure to electromagnetic radiation and comprises at least two functional groups (a11) comprising at least one bond activatable with electromagnetic radiation. Thermally curable binder component (a2) is polymerizable upon exposure to heat and has at least two functional groups (a21) which are reactive with functional groups (a31). Third component (a3) comprises at least 2.0 functional groups (a31) which are reactive with functional groups (a21). The value of UV/TH, the nonvolatile weight ratio of the sum of radiation curable component (a1) and optional reactive diluent (a4) to the sum of thermally curable binder component (a2) and thermally curable crosslinking component (a3) is from 0.20 to 0.60. Also disclosed are coated surfaces having both optimum porosity sealing and adhesion.

Claims

1. A coating composition curable upon exposure to both UV radiation and thermal energy, the composition comprising

(a1) a radiation curable component which polymerizes upon exposure to UV radiation, comprising at least one polymer or oligomer comprising

(a11) at least two functional groups comprising at least one bond activatable upon exposure to UV radiation,

(a2) a thermally curable binder component which polymerizes upon exposure to heat, comprising

(a21) at least two functional groups reactive with functional groups (a3),

(a3) a thermally curable crosslinking component comprising

(a31) two or more functional groups reactive with functional groups (a21), and

(a4) optionally, one or more reactive diluents,

wherein UV/TH is a value between 0.20 to 0.60.

4. The coating composition of claim 1 wherein the thermally curable component (a2) is selected from the group consisting of polyesters, epoxy functional materials, acrylics, and mixtures thereof.

5. The coating composition of claim 4 wherein thermally curable binder component (a2) comprises two or more isocyanate reactive functional groups (a21) per molecule.

6. The coating composition of claim 5 wherein thermally curable binder component (a2) is a polyester.

7. The coating composition of claim 6 wherein isocyanate-reactive functional groups (a21) are hydroxyl groups.

8. The coating composition of claim 1 wherein radiation curable component (a1) further comprises one or more functional groups (a12) which are reactive to functional groups (a31).

9. The coating composition of claim 8 wherein the ratio of NCO groups to the sum of functional groups (a12) and (a21) is less than 1.30.

10. The coating composition of claim 9 wherein functional groups (a12) and (a21) are isocyanate reactive functional groups and functional groups (a3 1) are isocyanate groups.

11. The coating composition of claim 10 wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is from 0.50 to 1.25.

12. The coating composition of claim 11 wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is from 0.75 to 1.10.

13. The coating composition of claim 12 wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is less than 1.00.

14. The coating composition of claim 13 wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is from 0.75 to 1.00.

15. The coating composition of claim 1 wherein thermally curable binder component (a2) comprises less than 5% by weight of aromatic ring moieties, based on the nonvolatile weight of thermally curable binder component (a2)

16. The coating composition of claim 15 wherein thermally curable binder component (a2) has no more than 2% by weight of aromatic ring moieties, based on the nonvolatile weight of thermally curable binder component (a2).

17. The coating composition of claim 16 wherein thermally curable binder component (a2) has between 0 to less than 2% by weight of aromatic ring moieties, based on the nonvolatile weight of thermally curable binder component (a2).

18. The coating composition of claim 1 wherein the thermally curable component (a2) has a polydispersity of less than 4.0.

19. The coating composition of claim 18 wherein the thermally curable component (a2) has a polydispersity of less than 3.5.

20. The coating composition of claim 19 wherein the thermally curable component (a2) has a polydispersity of from 1.5 to less than 3.5.

21. The coating composition of claim 20 wherein the thermally curable component (a2) has a polydispersity of from 1.75 to less than 3.0.

22. A method of making a coated substrate, comprising applying the coating composition of claim 1 to a substrate to provide a coated substrate.

23. The method of claim 22 further comprising subjecting the coated substrate to UV radiation to provide a UV cured coated substrate.

24. The method of claim 23 further comprising subjecting the UV cured coated substrate to heat to provide a UV and thermally cured coated substrate.

25. The method of claim 22 wherein the substrate comprises a plastic.

26. The method of claim 25 wherein the plastic substrate is a fiber-reinforced plastic substrate.

27. The method of claim 25 wherein the plastic substrate is SMC or BMC.

28. The method of claim 24 wherein the UV and thermally cured coated substrate is coated with one or more coating compositions to provide a coated UV and thermally cured coated substrate.

29. The method of claim 28 wherein the UV and thermally cured coated substrate is coated with at least one basecoat coating composition.

30. The method of claim 28 wherein the UV and thermally cured coated substrate is coated with at least one clearcoat coating composition.

31. The method of claim 28 wherein the coated UV and thermally cured coated substrate is substantially free of surface defects resulting from vaporous substrate emissions.

32. A coated substrate made by the method of claim 22.

2. The coating composition of claim 2 wherein UV/TH is between 0.25 to 0.50.

3. The coating composition of claim 2 wherein UV/TH is between 0.30 to 0.45.