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This paper describes the use of reactive vinyl ethers as key components in radiation
curable coatings and includes newly developed concepts for formulations, along with
properties of these systems. Vinyl ethers -- derived from the reaction of an alcohol with
acetylene -- are exceptionally reactive compounds with unique potential for use in
radiation curable coatings:
I. The vinyl ether double bond is highly electron rich and thus can form stable
carbocations; vinyl ethers therefore readily undergo acid catalyzed
polymerizations. In fact, this mechanism is the basis for the synthesis of the
commercially useful polymethyl vinyi ethers. Radiation cured cationic coatings
include 100% vinyl ether systems (1-6) and vinyl ethers blended with epoxy resins
(7-9); these cationic systems utilize iodonium or sulfonium salts as photoinitiators
(10).
II. Vinyl ethers undergo free radical polymerizations. Since vinyl ethers contain highly
electron-rich double bonds, they associate with highly electron-deficient maleate
or fumarate unsaturated polyesters to form charge transfer complexes
which, on polymerization, afford alternating copolymers. The important industrial
vinyl ether-maleic anhydride copolymers are synthesized in this way. Radiation
curable coating systems based on this chemistry are known (11-12).
of acrylate-based oligomers, low viscosity formulations permitting a wide range of
application techniques, safety in use, high cure speeds and decreased air
inhibition.
Ill. Vinyl ether monomers can be used with acrylate oligomers to afford hybrid curable
systems (13) which combine the advantages of both vinyl ether chemistry
and acrylate-based technology: excellent properties, choice of a wide range
