Nissan is developing 'cool paint' for cars cut summer cabin temperatures

TOKYO — Nissan showed Tuesday what it called a “cool paint” to keep people inside vehicles cooler, although the coating is six times thicker, making commercialization still a challenge.

The company's announcement Tuesday was timely, coming as Japan was enduring record sweltering temperatures.

Nissan Motor Co. tested the paint on vehicles scuttling around Tokyo’s Haneda airport, where there are plenty of unshaded areas that make it a good place to assess the technology. The vehicles with the special paint looked like ordinary cars, but felt much cooler to the touch.

The cool paint lowered the cars’ roof-panel temperature by 12 degrees Celsius (22 degrees Fahrenheit). The test vehicles' interiors were cooler by 5 C (9 F), according to Nissan. Cooler temperatures would be an advantage in particular for EVs, where energy used by the air conditioning can affect driving range.

Cooling materials already are widely used on buildings. In those applications, the material is laid on thick with a paint roller and is often chalky to the touch. Nissan's challenge was to make the specialized paint applicable by spray, and to take a clearcoat, like typical automotive paint. 

Toyota Motor Corp. has also been experimenting with paint that delivers lower cabin temperatures, mostly focusing on colors that refract the sun's rays.

Nissan says its cool paint contains "metamaterial," defining the substance as "synthetic composite materials with structures that exhibit properties not usually found in nature."

The "metamaterial" consists of two kinds of particles in the paint. One particle reflects near-infrared rays in the sunlight that would typically generate heat in the molecules of typical paint. The second particle is what Nissan calls "the real breakthrough": It creates electromagnetic waves that "counteract the sun's rays, redirecting the energy away from the vehicle into the atmosphere." 

It was developed with Radi-Cool of China, which developed a film, fabric and coating that cut heat. Radi-Cool works with various other Japanese companies, offering cooler-feeling hats and sun parasols. Nissan is the only Japanese automaker partnering with Radi-Cool.

Susumu Miura, a Nissan Research Center manager who led the project, said there were no discernible negative effects to people’s health from the electromagnetic waves emitted by the paint. Such waves are all around us, he said.

“My dream is to create coolers cars without consuming energy,” he said.