Trends in insulating varnish today

One of the newest, most rapidly advancing developments in the coatings field is the ultraviolet (UV) light cure of selected coating materials. This technique offers the potential for rapid and essentially non-polluting curing of the coatings.¹ Studies of UV initiated vinyl polymerizations can be traced back nearly fifty years; however, curing of commercial coatings by UV was developed only in the late 1960´s. Commercial UV cure applications in the United States have grown from two systems in 1971 to over thirty in 1972.² By the end of 1974, more than ninety systems are expected to be in operation.³ Present commercial systems are primarily used in the furniture industry to cure fillers and topcoats on particle boards. Some plastic and metal substrates are also coated. Potential uses include cures of protective and decorate coatings on metal, plastics, wires, laminates, etc. The new technique has been recently reviewed.⁴´⁵ Unsaturated polyesters, usually diluted with styrene, are the most widely used resins for UV cured coatings. Since large quantities of polyesters are used in the electrical industry, we have examined and compared the electrical properties of UV cured polyesters with those obtained from conventional thermally cured systems in order to establish the feasibility for use of the UV technique in the production of electrical insulations.