Stephen Craig Lapin

Radiation-Induced Cationic Curing of Vinyl Ethers

Recently there has been increasing interest in nonacrylate radiation-curable coatings. One factor that limits the choice of alternative chemical systems is the energy dose that is required to cure the coatings. Most UV-cured coatings are designed to cure with a dose of about 0.2 to 1.0 J/cm2. This corresponds to line speeds of about 20 to 100 m/min with two 80 W/cm medium-pressure mercury arc lamps. Most electron beam (EB)-cured coatings are cured with doses ranging from 2 to 10 Mrad. In spite of the fact that UV and EB irradiation are quite different in nature, simple energy unit conversions show that the total energy applied at the surface of the coating are actually quite similar for UV- and EB-cured coatings. Assuming a unit density liquid coating material applied at a thickness of 0.01 cm (ca. 4 mil), it follows that 2 Mrad = 20 J/g × 1 g/cm3 × 0.01 cm = 0.2 J/cm2.