Patent ID: 7173071

Claim:
A process for forming a protective film coating which process comprises curing a coating composition by irradiating said composition with ultraviolet radiation or daylight or with light sources equivalent to daylight, wherein said coating composition comprises a) at least one ethylenically unsaturated polymerizable compound, b) at least one durable and/or red-shifted reactable hydroxyphenylbenzotriazole UV absorber comprising an ethylenically unsaturated polymerizable group and c) a combination of photoinitiators comprising i) at least one Î±-hydroxy ketone photoinitiator and ii) at least one bisacylphosphine oxide photoinitiator, wherein the hydroxyphenylbenzotriazoles of component b) are of the formula where E 1 is t-butyl or Î±-cumyl and G 2 is phenylsulfone or â€”CF 3 ; wherein the alpha-hydroxy ketone photoinitiator of component c) i) is of formula where R 11 and R 12 independently of one another are hydrogen, C 1 â€“C 6 alkyl, phenyl, C 1 â€“C 6 alkoxy, phenyl, C 1 â€“C 6 alkoxy, OSiR 16 (R 17 ) 2 or â€”O(CH 2 CH 2 O) q â€”C 1 â€“C 6 alkyl, or R 11 and R 12 , together with the carbon atom to which they are attached, form a cyclohexyl ring; q is a number from 1 to 20; R 13 is OH, C 1 â€“C 16 alkoxy or â€”O(CH 2 CH 2 O) q â€”C 1 â€“C 6 alkyl; R 14 is hydrogen, C 1 â€“C 18 alkyl, C 1 â€“C 18 alkoxy, â€”OCH 2 CH 2 â€”OR 15 , a group CH 2 â•C(CH 3 )â€” or is I is a number from 2to 10; R 15 is hydrogen, â€”COCHâ•CH 2 or â€”COC(CH 3 )â•CH 2 ; and R 16 and R 17 independently of one another are C 1 â€“C 8 alkyl or phenyl; and wherein the bisacylphosphine oxide photoinitiator of component c) ii) is of formula wherein R 50 , is C 1 â€“C 12 alkyl, cyclohexyl or phenyl which is unsubstituted or is substituted by 1 to 4 halogen or C 1 â€“C 8 alkyl, R 51 and R 52 are each independently of the other C 1 â€“C 8 alkyl or C 1 â€“C 8 alkoxy, R 53 is hydrogen or C 1 â€“C 8 alkyl, and R 54 is hydrogen or methyl.