Acid-curable composition containing a masked curing catalyst, and a process for its preparation

A curable composition which comprises

• (a) an acid-curable resin, and
• (b) as the curing catalyst, a compound of formula I ##STR31## in which n is the number 1 or 2;
• R.sub.1 is anthryl, phenanthryl, phenyl, naphthyl or said phenyl or said naphthyl substituted by benzoyl or by 1, 2 or 3 radicals selected from the group consisting of --Cl, --Br, C.sub.1 -C.sub.8 -alkyl, phenyl, C.sub.1 -C.sub.8 -alkoxy, phenoxy, benzyloxy, C.sub.1 -C.sub.8 -alkylthio, phenylthio, --SCH.sub.2 CH.sub.2 OH, C.sub.1 14 C.sub.4 -alkyl-CONH-, benzoylamino and dimethylamino;
• R.sub.2 is hydrogen, --OH, C.sub.1 -C.sub.4 -alkoxy, --OSi(CH.sub.3).sub.3, --OCOCH.sub.3, C.sub.1 -C.sub.8 -alkyl or said alkyl substituted by phenyl;
• R.sub.3 is hydrogen, C.sub.1 -C.sub.8 -alkyl or said alkyl substituted by phenyl, by --CN, by benzoyl, by C.sub.1 -C.sub.4 alkylcarbonyl or by C.sub.2 -C.sub.5 -alkoxycarbonyl;
• R.sub.4 is hydrogen, C.sub.1 -C.sub.8 -alkyl, said alkyl substituted by --OH, by --Cl or by phenyl;
• phenyl, said phenyl substituted by --OH, by --Cl, by C.sub.1 -C.sub.4 -alkyl or by C.sub.1 -C.sub.4 -alkoxy;
• C.sub.2 -C.sub.6 -alkenyl, C.sub.8 -C.sub.9 -phenylalkenyl, furyl, thienyl, --CCl.sub.3, C.sub.5 -C.sub.6 -cycloalkyl or C.sub.5 -C.sub.6 -cycloalkenyl;
• or
• R.sub.1 and R.sub.3, R.sub.3 and R.sub.4 and R.sub.2 and R.sub.3, together with the carbon skeleton to which they are bonded, form a 5-membered or 6-membered ring which contains 1 to 5 --CH.sub.2 --, --CH(CH.sub.3)--, --C(CH.sub.3).sub.2 --, --O--, --S--, --SO--, --SO.sub.2 --, --CO--, --N(CO-C.sub.1 -C.sub.4 -alkyl)- or --N(COC.sub.6 H.sub.5)-- groups, and
• when n is 1, R.sub.5 is C.sub.5 -C.sub.6 -cycloalkyl, C.sub.7 -C.sub.9 -aralkyl, camphoryl, --CF.sub.3, --CCl.sub.3, --F, --NH.sub.2, C.sub.1 -C.sub.18 -alkyl, phenyl, said phenyl substituted by --Cl, --OH, C.sub.1 -C.sub.12 -alkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -alkyl-CONH--, benzoylamino, --NO.sub.2 or benzoyl;
• naphthyl, or said naphthyl substituted by --Cl, C.sub.1 -C.sub.12 -alkyl or C.sub.1 -C.sub.4 -alkoxy, or when n is 2, R.sub.5 is a --(CH.sub.2).sub.m group, in which m is a number from 2 to 8;
• phenylene, C.sub.1 -C.sub.12 -alkyl-substituted phenylene or naphthylene.