Toyota Tests Green as the New White
FRIDAY, FEBRUARY 19, 2016
The Prius is already known as an eco-friendly, fuel-efficient car, but Toyota recently revealed a paint job that promises to make the already frugal car even more environmentally responsible.
The 2017 Prius model is available in an exterior color called Thermo-Tect Lime Green, a solar-reflective paint meant to help the vehicle absorb less thermal gain on hot days and ultimately save even more on gas, Wired reported Friday (Feb. 12).
Toyota’s lime green paint may be ugly, but it can cut gas bills https://t.co/S1j7scuv2N pic.twitter.com/4TkKjNXMIC
— WIRED (@WIRED) February 12, 2016
With the solar-reflective properties of the paint, a driver may be less likely to turn on the air conditioning, which, according to the Department of Energy, can reduce fuel economy by 25 percent, it adds.
Going Beyond White
The bright green paint job, only available in Japan at this time, is the automotive industry’s first use of paint with solar-reflectance properties in a production line, Wired says.
The coating contains reflective titanium oxide (TiO2) particles and no carbon black, a common, heat-absorbent component in coatings.
Carbon black is popular among carmakers, according to Dr. Ronnen Levinson, a staff scientist with the Heat Island Group. He says that carbon black is often used to adjust colors, but even a little bit of carbon black will impact a paint’s solar reflectance.
By way of example, Levinson, whose research involved development of a pigment database for the Berkeley Lab that gauges the solar reflectance of hundreds of colors, says even a small amount of carbon black can reduce a red paint’s reflectance by as much as 15 to 40 percent.
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| By Ond?ej Mangl / Public Domain via Wikimedia Commons |
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Toyota's solar-reflective green paint contains reflective titanium oxide (TiO2) particles and no carbon black, a common, heat-absorbent component in coatings. |
“We expect heat increase control of around 5 degrees Celsius [9 degrees Fahrenheit] when comparing vehicle body surface temperature with and without thermal barrier function under the scorching sun in summer,” says Toyota spokesman Takashi Ogawa.
The car manufacturer says its special lime-green paint’s properties are so effective that it outperformed a car painted white during a two-hour outdoor summer test, technology news site SlashGear reported.
While the company acknowledges that other paints are known to offer significant reflective properties—white paint is 70 percent reflective, for instance, and the mica flakes in silver paint make it between 50 and 55 percent reflective, the tech site explains—Toyota’s announcement means they are now finding ways to provide the same benefits in a wider range of colors for their customers.
Likely to Catch On?
Wired cited a 2009 Heat Island Group study which indicated that, if every private car in Japan used this kind of paint, the country’s CO2 emissions could be cut by 210,000 tons a year (the country is reported to produce about 1.4 billion tons of emissions annually).
However, Toyota does acknowledge some challenges with the process, indicating that it can be difficult to balance the coating’s thermal properties with its durability. The larger titanium oxide particles may make the paint more reflective and heat resistant, Ogawa says, but they also make it harder for the paint to adhere onto the base coat.
While the car company won’t commit to how much a driver may see in gas savings, the special paint job is said to add an extra $350 to $380 to the purchase price.
Tagged categories: Automotive coatings; Coating chemistry; Coating Materials; Coatings Technology; Heat-resistive coatings; Solar reflectance; TiO2; Titanium dioxide
