Heat-curable powder coating composition
View Patent ↗The disclosure relates to a heat curable powder coating composition suitable for being cured at a temperature from 60 to 130° C. containing: a thermal initiation system and a resin system, wherein the reactivity of the thermal initiation system is such that the thermal initiation system provides a geltime between 2.5 and 1000 minutes at 60° C. in butane diol-dimethacrylate as measured according to DIN 16945 using 1 wt % of the thermal initiation system in 99 wt % of butane dioldimethacrylate, wherein the amount of thermal initiation system is chosen such that when the powder coating composition is applied to a substrate and cured at a temperature of 130° C. for 20 minutes.
1. A heat curable powder coating composition suitable for being cured at a temperature from 60 to 130° C. comprising:
a thermal initiation system and a resin system; wherein
the reactivity of the thermal initiation system is such that the thermal initiation system provides a geltime between 2.5 and 1000 minutes at 60° C. in butane diol-dimethacrylate as measured according to DIN 16945:1989-03 using 1 wt % of the thermal initiation system in 99 wt % of butane diol-dimethacrylate; and wherein
the amount of thermal initiation system is chosen such that when the powder coating composition is applied to a substrate and cured at a temperature of 130° C. for 20 minutes, the resulting coating resists at least 50 acetone double rubs; and wherein
the resin system comprises a resin and a co-crosslinker; and wherein
the resin contains reactive unsaturations which are carbon carbon double bonds connected directly to an electron withdrawing group; and wherein
the resin is a polyester; and wherein
the co-crosslinker is chosen from the group of acrylates, methacrylates, vinylesters, vinylethers, vinyl amides, alkyn ethers, alkyn esters, alkyn amides, alkyn amines, propargyl ethers, propargyl esters, itaconates, enamines and mixtures thereof; and wherein
the weight per unsaturation (WPU) of the co-crosslinker is higher than 150 and lower than 870 g/mole as determined using 1 H NMR; and wherein
the weight per unsaturation in the resin system is between 100 and 1000 g/mole as determined using 1 H NMR; and wherein
the powder coating composition is a one component system.
2. The composition according to claim 1 , wherein the geltime is at least 6 minutes and less than 1000 minutes.
3. The composition according to claim 1 , wherein the thermal initiation system comprises a peroxide.
4. The composition according to claim 3 , wherein, the peroxide is any of the following initiators: peranhydrides, peroxydicarbonates.
5. The composition according to claim 1 , wherein the reactive unsaturations are based on fumaric acid, maleic acid and/or itaconic acid.
6. The composition according to claim 1 , wherein the reactive unsaturations are based on fumaric acid and/or maleic acid.
7. The composition according to claim 1 , wherein the thermal initiation system comprises hydroquinones or catechols.
8. The composition according to claim 1 , wherein the co-crosslinker is chosen from the group of vinylethers, vinylesters, methacrylates, acrylates, itaconates and mixtures thereof.
9. The composition according to claim 1 , wherein the co-crosslinker is chosen from the group of vinylethers, vinylesters, itaconates and mixtures thereof.
10. The composition according to claim 1 , wherein the co-crosslinker is chosen from the group of vinylethers, vinylesters and mixtures thereof.
11. The composition according to claim 10 , wherein the resin has an acid value of less than 5 mg KOH per g resin.
12. The composition according to claim 1 , wherein the co-crosslinker is a vinylether.
13. The composition according to claim 12 , wherein the resin has an acid value of less than 5 mg KOH per g resin.
14. The composition according to claim 1 , wherein the resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin.
15. The composition according to claim 1 , wherein the weight per unsaturation of the co-crosslinker is higher than 150 g/mole and lower than 650 g/mole.
16. The composition according to claim 1 , wherein the weight per unsaturation of the co-crosslinker is higher than 150 g/mole and lower than 630 g/mole.
17. The composition according to claim 1 , wherein the weight per unsaturation of the resin is less than 1500 g/mole as determined using 1 H NMR.
18. The composition according to claim 1 , wherein the weight per unsaturation of the resin is less than 1150 g/mole as determined using 1 H NMR.
19. The composition according to claim 1 , wherein the weight per unsaturation of the co-crosslinker is higher than 150 g/mole and lower than 630 g/mole and wherein the weight per unsaturation of the resin is less than 1150 g/mole.
20. The composition according to claim 1 , wherein the resin and the co-crosslinker are the same.
21. The composition according to claim 1 , wherein the resin and the co-crosslinker are the same and the thermal initiation system comprises hydroquinones or catechols.
22. The composition according to claim 1 , wherein the resin is a polyester based on fumaric acid, wherein the co-crosslinker is a vinylether and wherein the thermal initiation system comprises a perdicarbonate and a hydroquinone.
23. The composition according to claim 22 , wherein the perdicarbonate is di(4-t-butylcyclohexyl)peroxydicarbonate or dimyristyl peroxydicarbonate, and wherein the hydroquinone is tert-butylhydroquinone or 2,3,5-trimethylhydroquinone.
24. The composition according to claim 1 , wherein the resin is a polyester based on fumaric acid, wherein the co-crosslinker is a vinylether and wherein the thermal initiator is benzoyl peroxide.
25. The composition to claim 1 , wherein the thermal initiation system comprises transition metal compounds of transition metals with atomic numbers from/equal to 21 up to/equal to 79.
26. The composition according to claim 1 , wherein the thermal initiation system comprises transition metal compounds of Mn, Fe, Co or Cu.
27. The composition according to claim 1 , wherein the thermal initiation system comprises metal salts or complexes or mixtures thereof of Mn, Fe, Co or Cu.
28. The composition according to claim 1 , wherein the resin has a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min.
29. The composition according to claim 1 , wherein the resin has a glass transition temperature of at least 45° C. as measured via DSC at a heating rate of 5° C./min.
30. The composition according to claim 1 , wherein the resin has a glass transition temperature of at least 40 and of at most 65° C. as measured via DSC at a heating rate of 5° C./min.
31. The composition according to claim 1 , wherein the resin has a number average molecular weight in the range of from 1500 to 8000 Da.
32. The composition according to claim 1 , wherein the resin has a number average molecular weight in the range of from 2100 to 4000 Da.
33. The composition according to claim 1 , wherein
the reactive unsaturations of the resin are based on maleic acid, fumaric acid, itaconic acid, acrylic acid and/or methacrylic acid, said resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin and a number average molecular weight in the range of from 1500 to 8000 Da and a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min; and
the co-crosslinker has a WPU higher than 150 g/mole and lower than 630 g/mole and said co-crosslinker is chosen from the group of vinylethers, vinylesters and mixtures thereof.
34. The composition according to claim 33 , wherein the reactive unsaturations of the resin are based on fumaric acid and/or maleic acid.
35. The composition according to claim 1 , wherein
the reactive unsaturations of the resin are based on maleic acid, fumaric acid, itaconic acid, acrylic acid and/or methacrylic acid, said resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin and a number average molecular weight in the range of from 1500 to 8000 Da and a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min; and
the co-crosslinker has a WPU higher than 150 g/mole and lower than 630 g/mole and said co-crosslinker is chosen from the group of vinylethers, vinylesters and mixtures thereof; and
the thermal initiation system comprises an inhibitor.
36. The composition according to claim 35 , wherein the reactive unsaturations of the resin are based on fumaric acid and/or maleic acid.
37. The composition according to claim 1 , wherein
the reactive unsaturations of the resin are based on maleic acid, fumaric acid, itaconic acid, acrylic acid and/or methacrylic acid, said resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin and a number average molecular weight in the range of from 1500 to 8000 Da and a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min; and
the co-crosslinker has a WPU higher than 150 g/mole and lower than 630 g/mole and said co-crosslinker is a vinylether.
38. The composition according to claim 37 , wherein the reactive unsaturations of the resin are based on fumaric acid and/or maleic acid.
39. The composition according to claim 1 , wherein
the reactive unsaturations of the resin are based on maleic acid, fumaric acid, itaconic acid, acrylic acid and/or methacrylic acid, said resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin and a number average molecular weight in the range of from 1500 to 8000 Da and a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min; and
the co-crosslinker has a WPU higher than 150 g/mole and lower than 630 g/mole and said co-crosslinker is a vinylether; and
the thermal initiation system comprises an inhibitor.
40. The composition according to claim 39 , wherein the reactive unsaturations of the resin are based on fumaric acid and/or maleic acid.
41. The composition according to claim 1 , wherein
the reactive unsaturations of the resin are based on maleic acid, fumaric acid, itaconic acid, acrylic acid and/or methacrylic acid, said resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin and an acid value of less than 10 mg KOH per g resin, and a number average molecular weight in the range of from 1500 to 8000 Da and a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min; and
the co-crosslinker has a WPU higher than 150 g/mole and lower than 630 g/mole and said co-crosslinker is a vinylether.
42. The composition according to claim 41 , wherein the reactive unsaturations of the resin are based on fumaric acid and/or maleic acid.
43. The composition according to claim 1 , wherein
the reactive unsaturations of the resin are based on maleic acid, fumaric acid, itaconic acid, acrylic acid and/or methacrylic acid, said resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin and an acid value of less than 5 mg KOH per g resin, and a number average molecular weight in the range of from 1500 to 8000 Da and a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min; and
the co-crosslinker has a WPU higher than 150 g/mole and lower than 630 g/mole and said co-crosslinker is a vinylether.
44. The composition according to claim 43 , wherein the reactive unsaturations of the resin are based on fumaric acid and/or maleic acid.
45. The composition according to claim 1 , wherein
the reactive unsaturations of the resin are based on maleic acid, fumaric acid, itaconic acid, acrylic acid and/or methacrylic acid, said resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin and an acid value of less than 10 mg KOH per g resin, and a number average molecular weight in the range of from 1500 to 8000 Da and a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min; and
the co-crosslinker has a WPU higher than 150 g/mole and lower than 630 g/mole and said co-crosslinker is a vinylether; and
the thermal initiation system comprises an inhibitor.
46. The composition according to claim 45 , wherein the reactive unsaturations of the resin are based on fumaric acid and/or maleic acid.
47. The composition according to claim 1 , wherein
the reactive unsaturations of the resin are based on maleic acid, fumaric acid, itaconic acid, acrylic acid and/or methacrylic acid, said resin has a hydroxyl value in the range of from 0 to 70 mg KOH per g resin and an acid value of less than 5 mg KOH per g resin, and a number average molecular weight in the range of from 1500 to 8000 Da and a glass transition temperature of at least 40° C. as measured via DSC at a heating rate of 5° C./min; and
the co-crosslinker has a WPU higher than 150 g/mole and lower than 630 g/mole and said co-crosslinker is a vinylether; and
the thermal initiation system comprises an inhibitor.
48. The composition according to claim 47 , wherein the reactive unsaturations of the resin are based on fumaric acid and/or maleic acid.
49. A process for the preparation of a powder coating composition according to claim 1 comprising the steps of:
(a) mixing the components of the powder coating composition to obtain a premix;
(b) heating the premix to obtain an extrudate;
(c) cooling down the extrudate to obtain a solidified extrudate; and
(d) breaking the solidified extrudate into smaller particles to obtain the powder coating composition.
50. A process for coating a substrate comprising the following steps:
(1) applying a powder coating composition according to claim 1 to a substrate to obtain a coated substrate; and
(2) heating the coated substrate.
51. A substrate that is fully or partially coated with a powder coating composition according to claim 1 .
52. The substrate according to claim 51 , wherein the substrate is a heat-sensitive substrate.
53. The substrate according to claim 52 , wherein the heat-sensitive substrate is wood.
54. The substrate according to claim 52 , wherein the heat-sensitive substrate is plastic.