Improving adhesion of acrylate resins

• US 6,500,878 B1
• Filed: 07/18/2000
• Issued: 12/31/2002
• Est. Priority Date: 07/19/1999
• Status: Expired due to Fees

• Current Assignee: BASF AG (BASF SE)
• Original Assignee: BASF AG (BASF SE)
• Inventors: Keil, Edmund, Beck, Erich, Enenkel, Peter, Menzel, Klaus, Reich, Wolfgang, Lokai, Matthias
• Primary Examiner(s): Berman, Susan W.
• Application Number:
  US09/619,140
• Time in Patent Office: 896 Days
• Field of Search: 522/170, 522/146, 522/100, 522/104, 522/173, 522/174, 522/134, 528/421, 528/418, 528/332, 525/523, 525/530
• US Class Current: 522/100
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 63/00 Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• CPC Class Codes: C09D 133/062 Copolymers with monomers not covered by C09D133/06
• CPC Class Codes: C09D 163/00 Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• CPC Class Codes: G03F 7/085 Photosensitive compositions characterised by adhesion-promoting non-macromolecular additives G03F7/075 takes precedence

Abstract

In a process for improving the adhesive strength of radiation-cured films of acrylate resins which comprise compounds having at least one amine group and at least one unsaturated acrylate group and, in particular, an amino-modified acrylate resin having a molecular weight Mn of at least 300, on substrates, the acrylate resins are admixed with amine-hardenable polyepoxides having an epoxide value of from 1 to 15 mol/kg such as polyglycidyl esters or polyglycidyl ethers. Preferred curable mixtures of amine-modified acrylate resins with polyepoxides have amine numbers of from 1 to 250 mg KOH/g and epoxide values of from 0.1 to 4 mol/kg. The mixtures applied as coating films to metal substrates or plastics substrates, in particular, are radiation-cured with, e.g., UV light and an at least partial amine hardening of the polyepoxide compounds in the mixture is conducted by thermal conditioning at, e.g., from 50 to 120° C.

Claims

1. A process for improving the adhesion of radiation-curable acrylate resins to substrates, which comprises:

admixing an acrylate resin mixture comprising an acrylate resin component containing at least one amine group and at least one radiation-curable unsaturated acrylate group and at least one amine-free acrylic resin with at least one curable polyepoxide compound having an epoxide value ranging from 1-15 mol/kg;

applying the resultant mixture to a substrate; and

curing the applied mixture by exposure to high energy radiation and by treatment at a temperature of above about 50°

C.

2. The process as claimed in claim 1, wherein the polyepoxide compound comprises at least 2 glycidyl ether or glycidyl ester groups.

3. The process as claimed in claim 1, wherein the acrylate resin component containing at least one amine group and at least one radiation-curable unsaturated acrylate group has an amine number ranging from 5 to 450 mg KOH/g.

4. The process as claimed in claim 1, wherein the acrylate resin mixture has an amine number ranging from 5 to 250 mg KOH/g.

5. The process as claimed in claim 4, wherein said amine number ranges from 5 to 100 mg KOH/g.

6. The process as claimed in claim 1, wherein the epoxide value of the mixture ranges from 0.1 to 4 mol/kg.

7. The process as claimed in claim 6, wherein said epoxide value ranges from 0.1 to 2 mol/kg.

8. The process as claimed in claim 7, wherein said epoxide value ranges from 0.1 to 1 mol/kg.

9. The process as claimed in claim 1, wherein the acrylate resin mixture further comprises reactive diluents.

10. The process as claimed in claim 1, which comprises applying said admixture of radiation-curable acrylate resin and polyepoxide as a film to the substrate, and then curing the acrylate resin mixture by irradiation and subsequently treating the applied film at a temperature of above about 50°

C.

11. The process as claimed in claim 1, wherein the polyepoxide compound at least partially reacts with the amine groups of the amine-modified acrylate resin by treatment at a temperature ranging from about 50 to 120°

C., thereby at least partially curing the polyepoxide compound.

12. The process as claimed in claim 1, wherein said admixture is applied to the substrate in plural layers, followed by irradiation which cures the layers and heat treatment at a temperature ranging from about 50 to 120°

C. for about 5 to 240 minutes.

13. The process as claimed in claim 1, wherein the acrylate resin mixture comprises from 1 to 20% by weight, based on the total amount of the acrylate resin mixture, of at least one photoinitiator, and wherein the admixture is applied to the substrate in plural layers followed by exposure of the applied layers to high energy, ultraviolet radiation to cure the layers.

14. The process as claimed in claim 1, wherein the substrate is a metal or plastic substrate.

15. The process as claimed in claim 1, wherein the acrylate resin containing at least one amine group is formed from an acrylate resin which is the reaction product of (meth)acrylic acid with a dihydroxy polyester, dihydroxy polyether, dihydroxy polyurethane or epoxy resin or is a reaction product of a hydroxyalkyl(meth)acrylate with a compound containing isocyanate groups.

16. The process as claimed in claim 1, wherein the acrylate resin containing at least one amine group is formed from an acrylate resin which is a polyester acrylate, a polyether acrylate, a urethane acrylate, an epoxy acrylate or a melamine acrylate having a number average molecular weight ranging from 300 to 15,000 g/mol.

17. The process as claimed in claim 16, wherein the number average molecular weight of said resin ranges from 400 to 3,000 g/mol.

18. A process for improving the adhesion of radiation-curable acrylate resins to substrates, which comprises:

admixing an acrylate resin component containing at least one amine group and at least one radiation-curable unsaturated acrylate group with at least one curable polyepoxide compound having an epoxide value ranging from 1-15 mol/kg;

applying the resultant mixture to a substrate; and

curing the applied mixture by exposure to high energy radiation and by treatment at a temperature of above about 50°

C.

19. The process as claimed in claim 18, wherein the polyepoxide compound comprises at least 2 glycidyl ether or glycidyl ester groups.

20. The process as claimed in claim 18, wherein the acrylate resin mixture has an amine number ranging from 5 to 250 mg KOH/g.

21. The process as claimed in claim 20, wherein said amine number ranges from 5 to 100 mg KOH/g.

22. The process as claimed in claim 18, wherein the epoxide value of the mixture ranges from 0.1 to 4 mol/kg.

23. The process as claimed in claim 21, wherein said epoxide value ranges from 0.1 to 2 mol/kg.

24. The process as claimed in claim 23, wherein said epoxide value ranges from 0.1 to 1 mol/kg.

25. The process as claimed in claim 18, wherein the admixture further comprises reactive diluents.

26. The process as claimed in claim 18, which comprises applying said acrylic resin component and polyepoxide as a film to the substrate, and then curing the acrylate resin mixture by irradiation and subsequently treating the applied film at a temperature of above about 50°

C.

27. The process as claimed in claim 18, wherein the polyepoxide compound at least partially reacts with the amine groups of the amine-modified acrylate resin by treatment at a temperature ranging from about 50 to 120°

C., thereby at least partially curing the polyepoxide compound.

28. The process as claimed in claim 18, wherein said admixture is applied to the substrate in plural layers, followed by irradiation which cures the layers and heat treatment at a temperature ranging from about 50 to 120°

C. for about 5 to 240 minutes.

29. The process as claimed in claim 18, wherein the admixture comprises from 1 to 20% by weight, based on the total amount of the acrylate resin, of at least one photoinitiator, and wherein the admixture is applied to the substrate in plural layers followed by exposure of the applied layers to high energy, ultraviolet radiation to cure the layers.

30. The process as claimed in claim 18, wherein the substrate is a metal or plastic substrate.

31. The process as claimed in claim 18, wherein the acrylate resin containing at least one amine group is formed from an acrylate resin which is the reaction product of (meth)acrylic acid with a dihydroxy polyester, dihydroxy polyether, dihydroxy polyurethane or epoxy resin or is a reaction product of a hydroxyalkyl(meth)acrylate with a compound containing isocyanate groups.

32. The process as claimed in claim 18, wherein the acrylate resin containing at least one amine group is formed from an acrylate resin which is a polyester acrylate, a polyether acrylate, a urethane acrylate, an epoxy acrylate or a melamine acrylate having a number average molecular weight ranging from 300 to 15,000 g/mol.

33. The process as claimed in claim 32, wherein the number average molecular weight of said resin ranges from 400 to 3,000 g/mol.