Scratches on cars removed by the action of sunlight

Scientists have invented a new coating, suitable for the bodywork of cars and other vehicles, capable of self-healing scratches with the help of sunlight.

Protecting the paint is essential to keep the surface of a car or similar in good condition. A coating applied on top of the paint must be transparent so that the color of the paint below continues to show through. However, it is difficult to provide a self-healing function while meeting all those requirements. Furthermore, materials with free molecular motion have high self-healing efficiency but low durability, while materials with high hardness and excellent durability have remarkably poor self-healing performance.

The team of Jin Chul Kim, Young il Park, and Ji-Eun Jeong at the Korea Research Institute of Chemical Technology (KRICT) has developed a clear coating material that meets all of the above requirements, with similar performance. that of commercial protective coating materials and that only needs sunlight to heal itself. Specifically, the type of sunlight that makes this self-healing possible is near-infrared light, in the wavelength range of 1,000 to 1,100 nanometers.

With the developed self-healing protection material, surface scratches can be cured within 30 minutes when exposed to sunlight. To demonstrate the self-healing ability of the developed coating material, the research team coated a miniaturized car model using a spray coating machine. When the car model was exposed to midday sunlight for about 30 minutes, the scratch completely disappeared and the surface of the coating material was restored. If a magnifying glass is also used to focus sunlight on the point of interest, self-repair can take less than 1 minute.

Self-healing surface of a model car after a scratch when exposed to concentrated sunlight through a magnifying glass (top) or direct sunlight (bottom). (Images: Korea Research Institute of Chemical Technology (KRICT))

Jin Chul Kim and colleagues present the technical details of their new coating in the academic journal ACS Applied Polymer Materials, under the title “Fast, Localized, and Low-Energy Consumption Self-Healing of Automotive Clearcoats Using a Photothermal Effect Triggered by NIR Radiation.” ”. (Font: NCYT by Amazings)