Mazda has developed a new solvent-based painting process and low-solvent paints that together reduce the emission of volatile organic compounds (VOC) to levels usually associated with a waterborne system. The "Three Layer Wet Paint System" combines the primer and top coat processes in a wet-on-wet procedure. It not only meets tough European VOC emission standards of 35g/m2, but also reduces CO2 discharge by 15%.
Here's how it works: In contrast with the traditional two-coat, two-bake method, the Mazda process sprays the primer, base and clear coats one after another and then runs the body through the oven once. (Eliminating time spent in the drying oven accounts for much of the energy savings.) To dispense with the bake normally necessary between the primer and top coat, Mazda uses a primer that contains a newly developed interface control resin. This resin has a different surface tension than the primer, causing it to move to the surface soon after application, where it creates a high-viscosity barrier between the primer and top coats.
Mazda also has developed a control system for paint flow and air pressure so efficient that the company reduced the number of paint robots by 25%, and integrated the primer and top coat processes—all without extending the paint line, another plus. Mazda says the new system both reduces paint consumption and achieves a higher quality finish. The automaker estimates the combination of new low-solvent paints and higher coating efficiency has decreased VOC emissions from substances like toluene and xylene by around 45%, a substantial reduction for a solvent-based process. Mazda has just implemented the new system at its Hofu Plant 1 in Japan. Future plans call for the technology to be extended to other plants and modified to accommodate waterborne painting methods.