Acrylates chosen from those of formula ##STR34## and those of formula ##STR35## in which R is a radical chosen from alkyl radicals containing from 1 to 12 carbon atoms, cycloalkyl radicals containing from 5 to 12 carbon atoms, and aryl, arylalkyl and alkylaryl radicals,
- Y is a radical chosen from alkylene radicals containing from 1 to 12 carbon atoms, arylene radicals containing from 6 to 12 carbon atoms with the exception of 1,4-phenylene, heterocyclic radicals whose ring contains from 5 to 10 members and whose heteroatom is chosen from nitrogen, oxygen and sulphur, and alkylarylene radicals in which the alkyl parts contains from 1 to 4 carbon atoms.