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We have investigated the simultaneous polymerization of mixtures of cationically (epoxides or
vinylethers) and radically (acrylates) curing components with EB to assess the feasibility of these so called hybrid systems for use in radiation curable coatings which could yield new properties, not accessible by the pure components alone. Also, one system containing an acrylate and a cationic component could give a variety of properties by just varying the amount of each of the components. Oxygen inhibition of the radically curing component may be suppressed since the cationic part could seal the top of the coating during EB curing, forming an oxygen barrier.
Since radicals are generated by EB, the acrylates do not need an initiator to start polymerization.
However, the cationic component needs an initiator' for polymerization and in this case iodonium salts were used:
salt I: 4,4'-dioctyldiphenyliodonium hexafluorophosphate
salt II: diphenyliodonium hexafluorophosphate.
The salts dissociate under irradiation and lead to ion-pair propagating species for cationic
polymerization.
At first some monofunctional monomers were used to investigate the effects of each of the
components on the polymerization mechanism and some results will be presented. Also some
modelsystems for coatings were cured by EB. It will be shown that hybrid systems are indeed feasible as radiation curable coatings.
