U.V.-curable coating composition and a process for coating a substrate with such coating composition

Claim 2

A coating composition which can be cured under the influence of ultraviolet light and is based on a U.V.-curable binder, a photoinitiator and a nitrogen-containing accelerator, characterized in that the accelerator is an N,N'-disubstituted cyclic 1,3-diaza compound having 5 to 9 ring atoms.

Claim 3

A coating composition according to claim 1, characterized in that the accelerator is an N,N'-disubstituted imidazolidine or hexahydropyrimidine compound.

Claim 4

A coating composition according to claim 1 or 2, characterizec in that the accelerator is a compound of the formula wherein R 1 and R 2 may be the same or different and represent a hydrocarbon group having 1-12 carbon atoms or a group, wherein R 7 has the meaning of a hydrocarbon group having 1-12 carbon atoms, and R 3 and R 4 may be the same or different and represent a hydrogen atom or a hydrocarbon group having 1-12 carbon atoms, or together form an alkylene group having 4-6 carbon atoms in the main chain, and A has the meaning of a -C-R 5 R 6 group or an oxygen atom positioned between two carbon atoms, and R 5 and R 6 are again the same or different and have the meaning of a hydrogen atom or an alkyl group having 1-4 carbon atoms, anc n is an integer from 0 to 4.

Claim 5

A coating composition according to claim 3, characterized in that the substituents R 1 -R 7 in the general formula are exclusively hydrogen atoms or unsubstituteo hydrocarbon groups and n is 0 or 1.

Claim 6

A coating composition.according to claim 1, characterized in that the accelerator is an oligomer having more than one cyclic diaza group.

Claim 7

A coating composition according to claim 5, characterized in that the oligomer has a molecular weight in the range of about 350 to about 2000.

Claim 8

A coating composition according to claim 1, characterizec in that the accelerator is a compound of the formula: wherein R 1 represents a hydrocarbon group having 1-12 carbon atoms or a group, where R 7 has the meaning of a hydrocarbon group having 1-12 carbon atoms, R 3 and R 4 may be the same or different and have the meaning of a hydrogen atom or a hydrocarbon group having 1-12 carbon atoms or together form an alkylene group having 4-6 carbon atoms in the main chain, and A has the meaning of a -CR 5 R 6 group or an oxygen atom positioned between 2 carbon atoms and R 5 and R 61 which may again be the same or different, have the meaning of a hydrogen atom or an alkyl group having 1-4 carbon atoms, and n is an integer from 0 to 4, and wherein R 8 represents an (x±y)-valent group formed by abstraction of (x+y) isocyanate groups from an (x+y)-valent polyisocyanate, x being an integer from 1 to 4 and y being an integer from 0 to 3 and (x+y) being equal to 2, 3 or 4 .

Claim 9

A coating composition according to any one of the claims 1-7, characterized in that the UV-curable binder is an at least one isocyanate group-containing adduct of a) an acrylic or methacrylic hydroxyester having 5 to 20 carbon atoms, and b) a polyisocyanate having 5 to 44 carbon atoms and 2 to 4 isocyanate groups.

Claim 10

A coating composition according to any one of the claims 1-7, characterized in that the UV-curable binder is an unsaturated epoxy resin.

Claim 11

A process for coating a substrate, characterized in that the substrate is provided with a coating composition according to any one of the claims 1-9, and the composition is subjected to radiation having a wave length of 90-600 nm.