UV-Curable Coating Composition Having Improved Sunlight Stability

Abstract

Disclosed is a radiation curable coating composition, including polymerizable, unsaturated compounds such as (meth)acrylates, vinyl compounds, or the like in a concentration range of 15-98% by weight, with an addition of 5-35% by weight, preferably 5-20% by weight, of organic UV absorber(s), wherein the UV absorber(s) has/have its/their maximum absorption coefficient in a wavelength range of <390 nm, preferably <350 nm, wherein the coating composition optionally includes other components in the amount of the balance to 100% by weight, and a method for curing such a coating composition. Also disclosed is a coating composition of this kind, wherein the organic UV absorber is radically polymerizable.

Claims

1-11. (canceled)

12. A radiation-curable coating composition comprising at least one polymerizable, unsaturated compound in a concentration range of 15-98% by weight and 5-35% by weight of one or more organic UV absorber wherein the UV absorber(s) has/have a maximum absorption coefficient in a wavelength range of <390 nm.

13. The radiation-curable coating composition of claim 12, wherein the polymerizable, unsaturated compound is a (meth)acrylate or vinyl compound.

14. The radiation-curable coating composition of claim 12, further defined as comprising 5-20% by weight organic UV absorber(s).

15. The radiation-curable coating composition of claim 12, wherein the UV absorber(s) has/have a maximum absorption coefficient in a wavelength range of <350 nm.

16. The radiation-curable coating composition of claim 12, wherein at least one organic UV absorber is radically polymerizable.

17. The radiation-curable coating composition of claim 16, wherein the coating composition includes other components in an amount of a balance to 100% by weight.

18. The radiation-curable coating composition of claim 17, further defined as comprising at least one or more of a photoinitiator, photosensitizer, bulking agent, pigment, additive and/or other UV absorber in a total concentration range of 0-80% by weight.

19. The radiation-curable coating composition of claim 18, further defined as compising at least one photosensitizer and/or photoinitiator with an absorption maximum in a range of less than 420 nm.

20. The radiation-curable coating composition of claim 19, wherein the at least one one photosensitizer and/or photoinitiator has an absorption maximum in a range of greater than 350 nm.

21. The radiation-curable coating composition of claim 12, comprising a proportion of monofunctional polymerizable components that is at least 50% by weight of all polymerizable components of the composition.

22. The radiation-curable coating composition of claim 21, wherein the proportion of monofunctional polymerizable components is at least 75% by weight of all polymerizable components of the composition.

23. The radiation-curable coating composition of claim 12, comprising a proportion of monofunctional polymerizable components that is at most 25% by weight of all polymerizable components of the composition.

24. The radiation-curable coating composition of claim 12, further defined as an ink.

25. The radiation-curable coating composition of claim 24, further defined as inkjet ink.

26. A method for curing a coating composition comprising: obtaining a radiation-curable coating composition of claim 12; and curing the radiation-curable coating composition with a light source having an emission peak of >350 nm.

27. The method of claim 26, wherein the light source is a UV/LED lamp or a UV/LD lamp having an emission peak of >360 nm.

28. The method of claim 27, wherein the light source has an emission peak of >390 nm.

29. A coating produced by curing a radiation-curable coating composition of claim 12.

Description

OVERVIEW OF THE FIGURES

[0084] FIG. 1: Illustration of the emission spectrum of a mercury-based UV lamp and the absorption range of Tinuvin 400.

[0085] FIG. 2: Comparison of the emission spectra of a mercury UV lamp and a UV/LED lamp and illustration of the absorption range of Tinuvin 400.

[0086] FIG. 3: Exemplary absorption curves of possible UV absorbers (the graphics was extracted from the brochure “Coatings that stay looking good—BASF performance additives” of BASF SE).

[0087] FIG. 1: In FIG. 1, an emission sprectrum of a mercury UV lamp is shown (black solid line). As can be seen, a plurality of emission peaks appear with this light source, most of which peaks are below 400 nm. The black dashed line shows the absorption spectrum of a possible UV absorber. As can be seen, the absorption spectrum largely superimposes the radiation emitted by the mercury lamp, and thus, UV radiation cannot optimally be made available for curing the coating. This results in an inadequately cured layer, or alternatively, in an insufficient concentration of the UV absorber in the coating in cases of self-consuming absorbers at relatively long exposition and curing times which results in a poor outdoor durability.

[0088] FIG. 2: In FIG. 2, the emission range of a standard mercury UV lamp, a UV/LED lamp and the absorption range of a possible UV absorber are compared. In a preferred embodiment of the invention, UV absorbers and UV/LED lamps are used which result in no or only a negligible overlap of the absorption or emission spectrum. As shown in FIG. 2, the emitted power of a UV/LED is about 4 times higher than that of a mercury radiator. Furthermore, the illustrated UV absorber absorbs only slightly in the wavelength range around 395 nm, which manifests itself in a high transparency of the UV absorber for the UV radiation provided by the UV/LED. In summary, this yields a good curing of the coating and, at the same time, a still sufficient concentration of UV absorbers to provide an adequately high UV protection for an outdoor stability.

[0089] FIG. 3 shows exemplary absorption curves of possible UV absorbers; the graphics was extracted from the brochure “Coatings that stay looking good—BASF performance additives” of BASF SE.

[0090] Below, exemplary embodiments of the disclosed invention are set forth. These examples are merely illustrative, without limiting the scope of the invention to these examples.

[0091] Examples of Outdoor Resistant Inks

TABLE-US-00001 Standard formu- Exp. Exp. Exp. Exp. Exp. Exp. Exp. Exp. Exp. Exp. Exp. Exp. Component lation 1 2 3 4 5 6 7 8 9 10 11 12 CN152* 1 1 1 1 CN386* 3 3 3 3 CN704* 2 2 2 2 Dow Corning 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 57 SR9003* 3.5 3.5 3.5 3.5 SR833S* 1.2 1.5 1.2 1.5 SR339C* 43.35 40.75 43.35 40.75 CN820* 2.2 1 2.2 1 SR217* 4 4 4 4 SR9051* 0.7 0.7 0.8 0.4 0.7 0.7 0.4 0.4 0.4 0.4 0.4 0.4 0.4 Tego Disperse 0.2 0.2 0.2 0.2 685 N-vinyl- 18 18 18 18 caprolactam WAKO Q1301 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Irgacure TPO 0.5 0.5 2 0.5 0.5 2 2 2 2 2 2 2 Speedure ITX 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Irgacure 819 4 4 4 2 4 4 2 2 2 2 2 2 2 Millbase 10.5 9 9 10.5 9 Yellow 1 Millbase 9 9 9 9 9 9 9 9 Yellow 2 Tinuvin 400 5 5 5 5 10 15 20 SR531* 60.35 58.75 53.75 48.75 43.75 43.75 38.75 43.75 38.75 SR506* 12 12 12 12 12 12 12 12 12 SR238* 3 5 5 5 5 5 5 5 5 RUVA-93 20 25 oMTP 20 25 Curing UV-LED UV/ UV/ UV/ Hg Hg UV/ UV/ UV/ UV/ UV/ UV/ UV/ LED LED LED lamp lamp LED LED LED LED LED LED LED Millbase Yellow 1: 21% Cromophtal Yellow D108, 7% Tego Disperse 685, 72% SR531* Millbase Yellow 2: SPECTRA RAY IJ YELLOW 150 UV Dispersion *Sartomer product code

TABLE-US-00002 Component Chemical Description Manufacturer CN152* aliphatic epoxy acrylate Sartomer-Arkema CN386* acrylated amine synergist Sartomer-Arkema CN704* polyester acrylate Sartomer-Arkema Dow Silicone Dow Chemical Corning 57 SR9003* propoxylated (2) neopentylglycol Sartomer-Arkema diacrylate SR833S* tricyclodecane dimethanol Sartomer-Arkema diacrylate SR339C* 2-phenoxyethyl acrylate Sartomer-Arkema CN820* acrylated acrylate Sartomer-Arkema SR217* tert-butylcyclohexyl acrylate Sartomer-Arkema SR9051* acid-based adhesion additive Sartomer-Arkema Tego high molecular weight polymer Evonik Disperse 685 WAKO Q1301 aluminum salt of N- WAKO nitrosophenylhydroxylamine Chemicals Irgacure TPO 2,4,6-trimethylbenzoyl BASF diphenylphosphine oxide Speedure ITX CAS Number 5495-84-1 Lambson (2-isomer) & 83846-86-0 Irgacure 819 phenylbis (2,4,6-trimethylbenzoyl) BASF phosphine oxide Tinuvin 400 2-hydroxyphenyl-s-triazine BASF SR531* cyclic trimethylolpropane formal Sartomer-Arkema acrylate SR506D* isobornyl acrylate Sartomer-Arkema SR238* 1,6-hexanediol diacrylate Sartomer-Arkema RUVA-93 CAS No: 96478-09-0 Otsuka Chemical Co. Ltd oMTP o-methylallyl Tinuvin P Polyscience Cromophtal yellow pigment BASF Yellow D108 SPECTRA RAY pigment dispersion SunChemical IJ YELLOW 150 UV Dispersion

TABLE-US-00003 ΔE QUV-A tests ΔE QUV-B tests Ink 1000 h 2000 h 300 h 600 h 900 h Standard formulation 3.02 6.89 4.14 6.57 8.17 Example 1 1.54 3.89 2.65 3.89 5.65 Example 2 1.44 3.54 2.35 3.54 5.05 Example 3 1.12 2.92 0.73 2.76 3.52 Example 4 3.05 7.05 4.20 6.75 8.05 Example 5 2.75 6.38 3.76 5.95 7.67 Example 6 1.02 2.52 0.52 2.12 2.85 Example 7 0.56 1.12 0.45 1.12 1.96 Example 8 0.48 1.09 0.48 0.93 2.05 Example 9 0.32 0.81 0.35 0.64 1.56 Example 10 0.31 0.79 0.41 0.55 1.20 Example 11 0.42 0.95 0.25 0.49 1.32 Example 12 0.31 0.80 0.30 0.55 1.03

[0092] The standard formulation mentioned in the above table in the first place is not an object of the present invention, as it contains no UV absorber. Below, it is explained with reference to the individual examples which changes were made compared to the standard formulation.

EXAMPLE 1

UV Absorber Was Added

EXAMPLE 2

Acrylate Matrix Was Adapted

EXAMPLE 3

Pigment Was Exchanged

EXAMPLE 4

Standard Formulation Was Cured with a Hg Lamp

EXAMPLE 5

Formulation of Example 1 Was Cured with a Hg Lamp

EXAMPLE 6

10% UV Absorber

EXAMPLE 7

15% UV Absorber

EXAMPLE 8

20% UV Absorber

EXAMPLE 9

20% Radically Polymerizable UV Absorber

EXAMPLE 10

25% Radically Polymerizable UV Absorber

EXAMPLE 11

20% Radically Polymerizable UV Absorber

EXAMPLE 12

25% Radically Polymerizable UV Absorber

[0093]