Radiation Curing of Pigmented Coatings

The Spectra Group Ltd. (SGL) contribution in responding to N94-213 is the ability to cure pigmented coatings with visible light at 500 or lower on demand. This is based On extensive development and testing of a series of new visible light photoinitiators, compounds which form reactive intermediates with visible light. These initiators are versatile and can be formulated in most radiation curable coatings - acrylates such as polyolacrylates, epoxy acrylates, silicon acrylates and urethane acrylates; unsaturated polyesters such as those used to coat particle board and as structural reinforced construction materials; and epoxies such as bis-phenyl-A-epoxide. Formulations of the initiators are infinitely stable in the dark, contain no volatile organic solvents, andcan be easily brushed on the surfaces to be coated. Curing is on demand; i.e, when thesurface is irradiated with light from a visible source. Alternatively, sunlight maybe used but the irradiation period depends on dose. The objective of Phase I is to (1)develop formulations of pigmented coatings suitable for marine applications;(2) evaluate initiator formulations such that the formulations can be cured with visible sources to a known depth; (3) develop the evaluation procedures for salt fog tests, impact tests, pencil hardness tests, and adherence tests; (4) establish which surface treatments enhance adhesion and (5) set up test protocols to routinely evaluate each.