UV Coating

About

Summary: Researchers in the Materials Accelerator at The University of Auckland have developed a method for precoating fibre-based or porous substrates that are otherwise difficult to powder coat, such as cement fibre board, gypsum board, and wood fibre composites including plywood and MDF. The invention enables these substrates to be powder coated with a far superior aesthetic finish, minimising or even eliminating defects at the high temperatures employed to cure powders.   The Challenge: In many contexts, powder coating of substrates is considered superior to liquid paints and similar coatings with a quality appearance and higher durability. However, powder coating fibre-based or porous substrates using conventional methods generally poses difficulties. These substrates have inconsistent electrical conductivity and a high moisture content that can cause moisture to escape while the powder coat is being cured. This tendency to vent gases during the curing process often leads to the finish developing pin holes and other defects. To achieve a smooth finish, the substrate must be precoated before the powder coating process begins.   The Solution: The technology is a method of precoating fibre-based or porous substrates with a UV curable primer before applying the powder coat. This precoating slows down moisture movement through the substrate, preventing excessive defects and improving durability of the finish. The precoating is applied to the substrate with photo-sensitive agents and is subsequently cured by the application of UV radiation, without any heating involved. The substrate may then be powder coated in the standard way. The precoated substrate exhibits more controlled electrical conductivity, resulting in stronger surface bond strength and increased impact resistance.   Benefits: Many fibre-based and porous substrates have desirable attributes such as low cost and high load bearing qualities. The technology allows these substrates to be powder coated with a smooth finish not achievable with standard powder coating methods. The precoating excludes environmentally unfriendly volatile organic compounds (VOCs), and the formula may include additional ingredients for pigmentation or increasing conductivity. This technology opens new opportunities for the production of sustainable, low cost, aesthetically pleasing and properly sealed fibre-based and porous substrates not previously available for powder coating.