Coating composition comprising: A) at least one compound having at least one olefinically unsaturated group and optionally at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) and/or A3) by addition or condensation reaction, A1) optianally at least one compound with at least one functional group b), A2) optionally at least one compound with at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) and/or A3) by addition or condensation reaction, A3) optionally at least one further compound having at least one olefinically unsaturated group and at least one functional group b) that is reactive towards the at least one functional group a) of compound A) and/or A2) by addition or condensation reaction, with the proviso, that component A) contains functional groups a) and/or component A2) with functional groups a) is present, and that at least one of components A1) and A3) with functional groups b) is present, or A) at least one compound having at least one olefinically unsaturated group and optionally at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) by addition or condensation reaction, A1) at least one compound with at least one functional group b), A2) optionally at least one compound with at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) by addition or condensation reaction, with the proviso that, compound A) contains at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) by addition or condensation reaction, and/or component A2) with functional groups a) is present, B) at least one photoinitiator and C) at least one triaryl phosphine, wherein the coating composition is free of organic phosphites and wherein the at least one functional group a) and the at least one functional group b) are combinations of: groups containing active hydrogen and isocyanate groups; hydroxyl groups and anhydride groups; amino groups and epoxide groups; acetoacetate groups and amino groups; acetoacetate groups and blocked amino groups; acetoacetate groups and (meth)acrylic acid ester groups. A) at least one compound having at least one olefinically unsaturated group and optionally at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) and/or A3) by addition or condensation reaction, A1) optianally at least one compound with at least one functional group b), A2) optionally at least one compound with at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) and/or A3) by addition or condensation reaction, A3) optionally at least one further compound having at least one olefinically unsaturated group and at least one functional group b) that is reactive towards the at least one functional group a) of compound A) and/or A2) by addition or condensation reaction, with the proviso, that component A) contains functional groups a) and/or component A2) with functional groups a) is present, and that at least one of components A1) and A3) with functional groups b) is present, or A1) optianally at least one compound with at least one functional group b), A2) optionally at least one compound with at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) and/or A3) by addition or condensation reaction, A3) optionally at least one further compound having at least one olefinically unsaturated group and at least one functional group b) that is reactive towards the at least one functional group a) of compound A) and/or A2) by addition or condensation reaction, A) at least one compound having at least one olefinically unsaturated group and optionally at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) by addition or condensation reaction, A1) at least one compound with at least one functional group b), A2) optionally at least one compound with at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) by addition or condensation reaction, with the proviso that, compound A) contains at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) by addition or condensation reaction, and/or component A2) with functional groups a) is present, A1) at least one compound with at least one functional group b), A2) optionally at least one compound with at least one functional group a) that is reactive towards the at least one functional group b) of compound A1) by addition or condensation reaction, B) at least one photoinitiator and C) at least one triaryl phosphine, wherein the coating composition is free of organic phosphites and wherein the at least one functional group a) and the at least one functional group b) are combinations of: groups containing active hydrogen and isocyanate groups; hydroxyl groups and anhydride groups; amino groups and epoxide groups; acetoacetate groups and amino groups; acetoacetate groups and blocked amino groups; acetoacetate groups and (meth)acrylic acid ester groups.