Outdoor weatherable photopolymerizable coatings
Plastic articles can be coated with polymerizable compositions containing a vinyl-functional crosslinkable film former, a large amount of benzotriazole and a copolymerizable monomer that solubilizes the benzotriazole. The cured compositions help protect the article from UV exposure and other weathering effects.
1. A homogeneous coating composition comprising:
a) at least one vinyl-functional crosslinkable film former;
b) more than 15 weight percent benzotriazole UV absorber; and
c) at least one copolymerizable monomer that solubilizes the benzotriazole.
2. A composition according to claim 1 wherein the film former comprises a di-, tri- or higher functional acrylate or methacrylate.
3. A composition according to claim 1 wherein the film former comprises butanediol diacrylate.
4. A composition according to claim 1 wherein the film former comprises hexanediol diacrylate, butanediol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate or trimethylolpropane triacrylate.
5. A composition according to claim 1 wherein the film former contains urethane functionality.
6. A composition according to claim 1 wherein the benzotriazole is substituted in the 5-position of the benzo ring by a thio ether, alkyl sulfonyl or phenyl sulfonyl moiety.
7. A composition according to claim 1 wherein the benzotriazole is substituted in the 5-position of the benzo ring by an electron withdrawing group.
8. A composition according to claim 1 wherein the benzotriazole comprises 2-(2-hydroxy-3,5-di-tert-amyl-phenyl)-2H-benzotriazole.
9. A composition according to claim 1 wherein the benzotriazole comprises 2-(2-hydroxy-3-alpha-cumyl-5-tert-octylphenyl)-2H-benzotriazole.
10. A composition according to claim 1 wherein the benzotriazole comprises 5-trifluoromethyl-2-(2-hydroxy-3-alpha-cumyl-5-tert-octylphenyl)-2H-benzotriazole.
11. A composition according to claim 1 wherein the monomer comprises isooctyl acrylate, 2-ethylhexyl acrylate, t-butyl acrylate, glycidyl methacrylate, benzyl methacrylate, isobornyl acrylate, isobornyl methacrylate, t-butylcyclohexyl acrylate, cyclohexyl acrylate, n-octyldecyl acrylate, butanediol diacrylate, 1-adamantyl acrylate, dicyclopentenyl acrylate or n-vinyl caprolactam.
12. A composition according to claim 1 wherein the monomer comprises isobornyl acrylate.
13. A homogeneous coating composition comprising:
(a) at least one vinyl-functional crosslinkable film former;
(b) more than 15 weight percent benzotriazole UV absorber; and
(c) at least one copolymerizable monomer that solubilizes the benzotriazole wherein the monomer comprises t-butylcyclohexyl acrylate.
14. A composition according to claim 1 wherein the film former and monomer are chemically distinct species.
15. A composition according to claim 1 wherein the film former and monomer are the same species.
16. A composition according to claim 1 comprising about 16 to about 35 weight percent benzotriazole based on the total weight of solids in the composition.
17. A composition according to claim 1 comprising about 20 to about 35 weight percent benzothiazole based on the total weight of solids in the composition.
18. A composition according to claim 1 comprising about 21 to about 35 weight percent benzotriazole based on the total weight of solids in the composition.
19. A composition according to claim 1 further comprising submicron inorganic particles.