What are Monomers
For efficient and effective UV curing of an ink, coating or adhesive, the formulator seeks to overlap the UV lamp output with the spectral absorption of the PI. The amount of PI in a typical UV formulation is usually very small, less than 5%. PIs typically absorb across a range of wavelengths, not a narrow band. Many existing UV formulations developed for curing with a typical mercury-arc lamp (shown as H-bulb) use a broad spectrum PI. While there is often some absorption within the UV LED output range, it is clear to see that much of the PI absorption range is wasted. A more efficient cure is possible with a formulation designed specifically for UV LED curing using a PI with concentrated absorption in the UV-A range.
The monomers in the formulation serve as the reactive diluent enabling the formulator to control viscosity for proper application (spraying, rolling, screen printing, etc.) of the uncured material. Rather than volatilizing, as is typical with conventional formulations, the monomer reacts and becomes part of the UV-cured material. The oligomers (and their backbone structure) determine the overall properties of the material. Monomers and oligomers are generally derivatives of acrylates or methacrylates containing polyurethanes, polyesters or polyethers.