in an organic solvent, such as preferably toluene or isopropanol, to a temperature of from 60 to 120??? C., more preferably from 70 to 80??? C. The unsaturated compound containing fluoro groups is used preferably in amounts of from 0.1 to 90% by weight, more preferably in amounts of from 1 to 60% by weight, and, with particular preference, in amounts of from 5 to 40% by weight based on the weight