acylates and methacrylates of the general formula ##STR18## where R22 is hydrogen or methyl and R23 is a straight chain or branched aliphatic, cycloaliphatic or aromatic group having up to 20 carbon atoms which is unsubstituted or substituted by one or more alkoxy, alkanoyloxy or alkyl of up to 12 carbon atoms, or by halo, especially chloro or preferably fluoro, or C3 -C5 polyalkyleneoxy of 2 to a