Design & Technology
Coating the future with water-based paints November 7th, 2007
By Kyehwan Roh
Environmental Management Team
Environment-friendly cars touting buzzword such as “Eco,” “Green,” and “Blue’ have been the rave at recent motor shows. This trend is a direct reflection of the efforts being made by automakers around the globe to reduce air pollution by curbing carbon dioxide (CO2) emissions from vehicles.
This has also been a key mission of Kia Motors. On top of developing eco-friendly cars, we have continued to work on reducing various pollutants generated during the manufacturing process. One of our key efforts is replacing oil-based paints with water-based paints in the coating process of vehicles manufactured in Hwasung (Korea), Slovakia and China plants.
The basic automotive coating process consists of three steps: electrodeposition, surface and top coating (base, clear). Oil-based paint is typically used for surface and top coating. But this is not the case anymore. Following the electrodeposition painting process, water-based paint is used for surface and top coating (base). Oil-based paint is used only in the last clear coating process.
By using water-based paint instead of oil-based paint, we cut volatile organic compounds (VOC) by 70% (120g/㎡→35g/㎡). And unlike traditional coating which requires three drying processes, water-based paint requires only two, thereby reducing greenhouse gas (CO2) emissions by 15%.
Of course, this eco-friendly process also has its share of problems. Due to its property of dissolving well in water, an increase in waste water treatment costs and COD (Chemical Oxygen Demand) is inevitable with water-based point. Nevertheless, we are tirelessly seeking ways to resolve these issues.
Some people worry whether using water-based paint would make the coating job more difficult. Others are concerned that the paint dissolves in water or that water may seep into the paint after the coating process. But there is no need to worry. Water-based paint is easy to work with and once the paint dries, its waterproof membrane capability, very similar to oil-based paint, helps to protect the paint job from water.
Kia Motors plans to gradually expand the use of water-based paint to all models in our line-up as part of our commitment to protecting the environment through reduction of VOC and CO2 emissions.