Primers form an adhesion-promoting interface between substrate and topcoat. It functions as a barrier coating that enhances the long-term adhesion and weatherability of the substrate and coatings applied to the primer. In addition, the primer layer stabilizes adhesion to low energy surfaces and prevents delamination upon additive-rich plastics such as those substrates containing internal mold release, UV absorbers, colorants, anti-static agents, and fire retardants.
Coupling agents impart a thin, chemically reactive surface to the substrate without increasing overall coating thickness. Various organic and organometallic coupling agents can be used to cast a near monomolecular layer which forms effective bonds with the substrate and topcoat.
Primers and coupling agent solutions are best applied at a minimum thickness on plastic, metal, and glass substrates. Rigid topcoats may be prone to craze or crack if primer thickness is too high. Coupling agents used at an excessive concentration can reduce clarity and may cause cosmetic defects or pot life reduction of topcoat solution in contact with uncured adhesion promoters.
Liquid solutions are easily applied by a variety of application techniques including dip, flow, spin, and spray methods.
An aqueous urethane primer developed to improve adhesion and impact resistance of plastic ophthalmic resins and polycarbonate substrates. The CC-158 primer layer provides a cushion coating on resin lenses and improves hardcoat adhesion during vacuum AR coating/metallization. Supplied at 20% or 35% solids in water.
The SP-1 Primer is a solvent-based acrylic resin primer that is compatible with many plastic substrates requiring a hardcoat or other topcoats. It is supplied at 3% solids in methoxypropanol.
SP-26 is a solvent-based coupling agent solution that improves adhesion of siloxane, melamine, urethane, and acrylic coatings on plastic, metal, and glass. It is supplied as a concentrated solution that requires dilution prior to use.