Mazda’s Green Paint Process (other colors, too)

While most people probably think “powertrain” when environmental aspects of vehicles are thought of, there is something that all cars and trucks share that has a big effect on their environmental impact: painted bodies.

While most people probably think “powertrain” when environmental aspects of vehicles are thought of, there is something that all cars and trucks share that has a big effect on their environmental impact: painted bodies.

Not only do vehicular paints typically contain solvents, but there’s plenty of energy involved in curing the paint.

Mazda Motor Corp. researchers came up with a painting process that helps significantly reduce emissions from the painting process, and two of the researchers, Takakazu Yamane and Tsutomu Shigenaga, received the 2011 "Japan Business Federation Chairman's Award for Invention" from the Japan Institute of Invention and Innovation (JIII) for the “Three Layer Wet Paint System.” They will share the award with Masakazu Watanabe and Takuhiro Kakii of Nippon Paint Co., Ltd.

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Like typical paint processes, there are three layers applied: the primer, colored base coat, and clear top coat. But the difference with the Three Layer Wet Paint System is that rather than drying each coat before applying the next, the coats are applied in succession without drying. What’s more, they had a goal of reducing the volatile organic compound (VOC) emissions associated with paints, so they developed low-solvent paints for use with the process.

The reduction in solvents added another challenge to things: usually, reduced solvents means increased viscosity, which makes the material difficult to work with. So they reduced the size of the paint molecules.

But there was still work to be done, because if you have low-viscosity fluids like paint, and you apply one on top of the other while they are still liquid, there is a tendency for them to mix. And that would lead to an unacceptable class-A surface.

So they had to develop an interface control resin, which is added to the primer. Consequently, they are able to put the color on top of the primer without the typically required drying step, and the clear coat on top of the color coat.

The environmental benefit: VOC emissions from the paint shop are reduced 45% and CO2 emissions are reduced 15%.

They developed the Three Layer Wet Paint System in 2002, and since then, not only has Mazda rolled it out to its plants, but it has been deployed by vehicle manufacturers throughout the world.

And in the meantime, Mazda researchers have come up with another environmentally beneficial paint process: the Aqua-tech Paint System, which is like its processor, but which uses water-based, not solvent-based, paints, so there are still fewer VOC emissions. Mazda is currently deploying the Aqua-tech Paint System in its factories.