Process for curing acid-curable finishes

Claim 1

A process for curing baking finishes which contain an acid-curable resin and, as a curing catalyst, a blocked sulfonic acid of the formula I ##STR21## in which m is 0 or 1 and n is 1 or 2, R 1 is C 1 -C 12 -alkyl, C 1 -C 4 -halogenoalkyl, C 2 -C 6 -alkenyl, C 5 -C 12 -cycloalkyl, C 6 -C 10 -aryl which is unsubstituted or mono- or poly-substituted by halogen, C 1 -C 16 -alkyl, C 1 -C 4 -alkoxy, phenoxy, phenyl or nitro, furyl, thienyl, C 7 -C 12 -aralkyl, C 1 -C 8 -alkoxy, C 5 -C 8 -cycloalkoxy, phenoxy or H 2 N--CO--NH--, R 2 is as defined for R 1 or is --CN, C 2 -C 5 -alkanoyl, benzoyl, C 2 -C 5 -alkoxycarbonyl, phenoxycarbonyl, --N(R 4 )(R 5 ), morpholino or piperidino, or R 1 and R 2 , together with the atoms to which they are linked, form a 5-membered to 8-membered ring to which 1 to 2 benzo radicals can be fused, R 4 being hydrogen, C 1 -C 12 -alkyl, phenyl, C 2 -C 9 -alkanoyl or benzoyl and R 5 being hydrogen, C 1 -C 12 -alkyl or cyclohexyl, and R 3 , with n=1, is C 1 -C 18 -alkyl, C 6 -C 10 -aryl which is unsubstituted or mono- or poly-substituted by halogen, C 1 -C 4 -halogenoalkyl, C 1 -C 16 -alkyl, C 1 -C 4 -alkoxy, C 1 -C 4 -alkyl-CONH-, phenyl-CONH-, benzoyl or nitro, C 5 -C 12 -cycloalkyl, C 7 -C 9 -aralkyl, camphoryl, --CF 3 , --CCl 3 or --NH 2 , and, with n=2, R 3 is C 2 -C 12 -alkylene, or unsubstituted or C 1 -C 12 -alkyl-substituted phenylene, naphthylene, diphenylene or oxydiphenylene, which comprises irradiating the finish with short-wave light, whereby the free sulfonic acid is formed, and then fully curing it at an elevated temperature.