Beneficial Effect of CO2 on the UV-curing of Acrylate Coatings

The inhibitory effect of oxygen on the photoinitiated polymerization of a polyurethane-acrylate resin has been completely eliminated by operating in a carbon dioxide atmosphere. The high-speed polymerization was followed in real-time by infrared spectroscopy, thus allowing conversion versus time curves to be directly recorded for curing reactions occurring in a fraction of a second. The importance of 02 inhibition was shown to depend on a number of factors, such as the 02 concentration, the film thickness, the resin viscosity, the sample temperature, the type and concentration of photoinitiator and the light intensity. 2 inerting was required for achieving an effective surface cure of fluid resins exposed to low intensity UV radiation.