A new blocking agent of isocyanates

The synthesis of a new liquid blocking agent of isocyanates is described, the 2-formyloxyethyl methacrylate (FEMA). It possesses simultaneously two chemical functions on its molecule. The first function, bearing a labile hydrogen, can block an isocyanate group and the second, a double bond, can polymerise by radical pathway after the unblocking reaction. This fact represents a great advantage of avoiding the blocking agent release in atmosphere. Therefore the final material will contain two interpenetrated polymers polyurethane and polyacrylate. The blocking and unblocking kinetics using two aliphatic and aromatic diisocyanates and two diols were studied.