lae: wherein n represents an integer from 1 to 3, or a pluralin which the oxygen atom is bonded to a carbon atom ity of phenylene or cyclohexylene radicals connected of the radical R, and T represents a divalent organic to one another by a simple valency bond or by an inert radical possessing from 2 to 24 carbon atoms, the vaatom or group such as O or -S, an alkylene lencies of which are on adjace