Nissan trials cool paint technology

JAPAN: Car manufacturer Nissan has been trialing an innovative paint aimed at helping lower a vehicle’s ambient cabin temperature in summer and reduce the energy usage of the air conditioning system.

Developed in partnership with Malaysian company Radi-Cool, a specialist in radiative cooling products, the paint incorporates metamaterial, synthetic composite materials with structures that exhibit properties not usually found in nature.

Last November, Nissan commenced a 12-month feasibility trial of the cool paint applied to a Nissan NV100 service vehicle operating at Tokyo-Haneda International Air Terminal. 

With its large, open tarmac, Haneda airport was seen as the perfect environment to conduct real-world evaluation of the paint’s performance under an exposed high-temperature environment.

The results to date are said to have been impressive. Parked side-by-side under the sun with a vehicle featuring traditional automotive paint, the vehicle treated in Nissan’s cool paint is said to have recorded up to a 12ºC reduction in exterior surface temperatures and up to 5ºC cooler interior.

The metamaterial embedded within Nissan’s cool paint features two microstructure particles that react to light. One particle reflects near-infrared rays in the sunlight that would typically cause molecular level vibrations within the resin of traditional paint to produce heat.

The second particle creates electromagnetic waves that counteract the sun’s rays, redirecting the energy away from the vehicle into the atmosphere. 

Combined, the particles in Nissan’s cool paint reduce the transfer of heat into surfaces such as the roof, hood, doors and panels.

Leading the development is Dr. Susumu Miura, senior manager and expert at the Advanced Materials and Processing Laboratory, Nissan Research Center. He played a leading role in Nissan’s award-winning noise-reducing acoustic material, and has dedicated much of his career at Nissan to exploring ways to make cars quieter, cooler and more efficient.

“My dream is to create cooler cars without consuming energy,” explained Dr Susumu Miura, senior manager and expert at Nissan Research Center’s Advanced Materials and Processing Laboratory. “This is especially important in the EV era, where the load from running air-conditioning in summer can have a sizeable impact on the state of charge,” he said.

While radiant cooling paint isn’t new, it is typically used for buildings and structures. It’s often very thick, requiring application by a paint roller. Devoid of any clear topcoat, it can leave a chalky residue when touched.

Key challenges Miura had to consider when developing an automotive version, was to ensure it could incorporate a clear topcoat, be applied via a spray gun (not a roller), and meet Nissan’s rigorous internal standards for paint quality.

Since commencing the development in 2021, Miura and his team have tested over 100 samples, and are currently evaluating a thickness of 120 microns, approximately six times thicker than typical automotive paint. They have confirmed resistance to salt and chipping, peeling, scratches, chemical reactions, along with colour consistency and repairability. As development progresses, Miura and his team continue to explore thinner options that deliver the same level of cooling performance.