Dual cure coating composition and process for using the same

• US 20030083397A1
• Filed: 08/28/2001
• Published: 05/01/2003
• Est. Priority Date: 08/28/2001
• Status: Abandoned Application

• Current Assignee: BASF Corporation (BASF SE)
• Original Assignee: BASF Corporation (BASF SE)
• Inventors: Caillouette, Lyle, Zimmer, Marcy, Bradford, Christopher J., Rischke, Jennifer A., OʼDonnell, Ryan F.
• Application Number:
  US09/940,748
• Publication Number:
  US 20030083397A1
• Time in Patent Office: Days
• US Class Current: 522/173
• CPC Class Codes: C08F 283/006 on to polymers provided for in C08G18/00 C08F283/004 takes precedence
• CPC Class Codes: C08F 283/01 on to unsaturated polyesters C08F283/004 takes precedence
• CPC Class Codes: C08F 290/141 Polyesters; Polycarbonates
• CPC Class Codes: C08F 290/147 Polyurethanes; Polyureas
• CPC Class Codes: C08G 59/18 Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
• CPC Class Codes: C08J 3/243 Two or more independent types of crosslinking for one or more polymers
• CPC Class Codes: C09D 175/06 from polyesters
• CPC Class Codes: C09D 175/16 having terminal carbon-to-carbon unsaturated bonds
• CPC Class Codes: C09D 201/025 containing nitrogen atoms
• CPC Class Codes: G11B 5/7021 containing a polyurethane or a polyisocyanate

Abstract

The dual cure coating composition requires electromagnetic radiation and heat energy to cure and comprises a radiation curable component (a1), a thermally curable binder component (a2), and a thermally curable crosslinking component (a3). Radiation curable component (a1) polymerizes upon exposure to electromagnetic radiation, and comprises at least two functional groups (a11) comprising at least one bond activatable with electromagnetic radiation, and one or more isocyanate-reactive functional groups (a12). Thermally curable binder component (a2) polymerizes upon exposure to heat and has at least two isocyanate-reactive functional groups (a21) and substantially no functional groups (a22) having bonds activatable upon exposure to electromagnetic radiation. Third component (a3) comprises at least 2.0 isocyanate groups (a31) per molecule. The ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is less than 1.30. The invention provides methods of making coated surfaces that have 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

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

(a12) one or more isocyanate-reactive functional groups,

(a2) a thermally curable binder component which polymerizes upon exposure to heat, consisting of one or more oligomers or polymers having

(a21) at least two isocyanate-reactive functional groups, and

(a22) substantially no functional groups having bonds activatable upon exposure to UV radiation, and

(a3) a thermally curable crosslinking component comprising at least 2.0 isocyanate groups per molecule,

wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is less than 1.30.

2. The coating composition of claim 1, wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is from 0.50 to 1.25.

3. The coating composition of claim 2 wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is from 0.75 to 1.10.

4. The coating composition of claim 1 wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is less than 1.00.

5. The coating composition of claim 3 wherein the ratio of NCO groups to the sum of isocyanate-reactive functional groups (a12) and (a21) is from 0.75 to 1.00.

6. The coating composition of claim 1 wherein isocyanate-reactive functional groups (a12) and (a21) are hydroxyl groups.

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

8. The coating composition of claim 7 wherein the thermally curable binder component (a2) has a polydispersity of less than 3.5.

9. The coating composition of claim 8 wherein the thermally curable binder component (a2) has a polydispersity of from 1.5 to less than 3.5.

10. The coating composition of claim 9 wherein the thermally curable binder component (a2) has a polydispersity of from 1.75 to less than 3.0.

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

12. The coating composition of claim 7 wherein thermally curable binder component (a2) is a polyester.

13. The coating composition of claim 1 wherein thermally curable binder component (a2) has no more than 5% by of aromatic ring structures, based on the nonvolatile weight of thermally curable binder component (a2).

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

15. The method of claim 14 further comprising subjecting the coated substrate to UV radiation to provide a UV cured coated substrate.

16. The method of claim 15 further comprising subjecting the UV cured coated substrate to heat to provide a UV and thermally cured coated substrate.

17. The method of claim 14 wherein the substrate comprises a plastic.

18. The method of claim 17 wherein the plastic substrate is a fiber-reinforced plastic substrate.

19. The method of claim 17 wherein the plastic substrate is SMC or BMC.

20. The method of claim 15 wherein the UV cured coated substrate is coated with one or more coating compositions to provide a coated UV cured coated substrate.

21. The method of claim 16 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

22. The method of claim 20 wherein the UV and thermally cured coated substrate is coated with at least one basecoat coating composition.

23. The method of claim 20 wherein the UV and thermally cured coated substrate is coated with at least one clearcoat coating composition.

24. The method of claim 21 wherein the coated UV and thermally cured coated substrate is substantially free of surface defects resulting from vaporous substrate emissions.

25. A coated substrate made by the method of claim 14.