(3) at least one reactive urea derivative having the generic formula: ##STR1## wherein each of R1, R2, R3 and R4 is a monovalent radical selected from the class consisting of hydrogen, alkyl groups having 1 to about 10 carbon atoms, hydroxyalkyl groups having 2 to about 4 carbon atoms and one or more hydroxyl groups, and hydroxypolyalkyleneoxy groups having one or more hydroxyl groups and with the