Radiation-Curable Coatings on the Upsweep of a Strong Growth Curve
In about 1970 almost all — over 90% — industrial coatings were applied from organic solvents and at low solids. To develop good properties, high-molecular-weight polymers were dissolved in solvents and applied at low solids of about 25% or less. However, at this time, a revolution was taking place in the coatings industry due to ecological and health concerns, and an OPEC-caused energy shortage that had people standing in lines at filling stations to obtain petroleum-based gasoline. Increasing solvent costs were also important economic factors at the time.
To combat these factors, what were then called new technologies were conceived — powder coatings, high-solids coatings, waterborne coatings and radiation-curable coatings. The coating industry didn’t want to change, but change it did. Crosslinking assumed a new importance as a way to develop properties from small bits of polymers known as oligomers. All the new technologies found a place, but with the exception of radiation-cure coatings, most required that a polymer be first made and fabricated to fit the technology and then the cure mechanism applied. Radiation curing used liquid, monomeric materials that were 100% solids in nature and that instantly “dried” to form hard coatings when exposed to radiation from electron beams (EB) or ultraviolet (UV) light. Sales were small, as might be expected, in the early 1970s, but it was a base and through the efforts of many people, radiation-cure technology grew and today it is a sizable business.