Scientists from Asia Pacific’s largest paint and coating manufacturer have developed a new “ultra-black” automotive coating using carbon nanotubes that absorbs over 99% of the light it receives, resulting in the darkest black of any currently available paint or coating.
The NIPSEA Group’s research team said its new ultra-black coating, which they describe as “deep, jet black,” meets stringent automotive standards, a critical requirement in markets like China, where trendy, luxury vehicles in the darkest colors are in high demand.
Carbon Nanotubes Absorb Light to Create Darkest Black “Ultra-Black” Coating
According to a statement announcing the new ultra-black coating, BMW first introduced a concept car in 2019 with a vertically aligned carbon nanotube (VACNT) array outer coating. Due to the unique material properties of carbon nanotubes, including the ability to bend or absorb light, the researchers said that its introduction “set off a race” among auto manufacturers to create a similar, ‘black hole’ effect with a pronounced dark appearance.
“Automotive coating companies have been actively pursuing innovations in color technology to develop mass-processable ultra-black coating solutions with extreme blackness,” explained Zhiwei Liu, a research chemist with the company’s Color Technology Group, Core R&D, and an author on the study outlining the new coating.
The researchers note that ultra-black coatings are in unusually high demand in Asian countries, where having the darkest vehicle can represent a status symbol. has become a “key selling point” in China.
“Deep black finishes have long been the premium choice and signature color for luxury cars due to their elegant appearance, powerful visual impact, and luxurious undertone,” the researcher explained.
Although scientists have explored more practical ways to achieve the desired ultra-black effect, the new research once again leverages the unusual properties of carbon nanotubes to create an ultra-black coating that is darker than even the darkest commercially available alternative.
Creating a Stable Composite That Meets Automotive Standards
According to the team’s statement, they began by exploring methods to combine the benefits of carbon nanotubes with a black pigment that would serve as the coating’s color base. Critically, the team needed to create a nano-sized carbon black pigment-carbon nanotube composite that was also stable at a wide range of temperatures. and moisture conditions.
After exploring several formulations, Liu and colleagues succeeded in a stable nanotube-pigment composite. Next, the team incorporated the new carbon nanotube-based mixture into a coating binder and sprayed it onto a model car.
Because the new ultra-black coating uses structural absorption of light rather than the carbon black dispersion method used in current approaches, tests revealed an average absorption of 99.90% across all visible wavelengths. The team said its new coating also displayed “excellent long-term stability” during water and humidity tests.
Although the light absorption levels set a new standard for the darkest achievable automotive coating, Liu said advancements in dispersing technology and equipment leave his team “room for improvements.” The researcher highlighted potential advancements in “practical processability of carbon-nanotube-containing nanomaterials.”
Liu and colleagues also noted that increasing the proportion of carbon nanotubes in the material could further increase its light-absorbing capacity. However, they conceded, this approach “would also bring difficulties in industrial-grade processability.”
Future Improvements Include Even Darker Multi-Layer Options
When discussing potential future improvements, the team said scientists could fabricate multilayered ultra-black coatings. In theory, they note that this approach could result in a “gradient refractive index that reduces interface reflection and further enhances light absorption efficiency,” producing an even darker look than their single-layer version.
Although the ultra-black automotive coating is not yet commercially available, the team said they have already completed a “proof of concept” manufacturing design. Still, they conceded, given technical and regulatory challenges that remain, “it may still be a while before ultra-black cars made with this film will be able to hit the road.”
“Further efforts will focus on the verification of coating application window and the comprehensive film performance validations of carbon black pigment-carbon nanotube composite-based ultra-black automotive coating,” Liu concluded.
The study “Robust ultra-black automotive coating with structural absorption and high absorption efficiency based on waterborne carbon black/CNT composite” was published in Matter & Light.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.