Coatings play important roles on the roads around us.

Asphalt mixture, which is most commonly used for road pavement, absorbs sunlight due to its black color and sometimes makes the road surface temperature exceed 60°C in summer.
The solar heat reflective paints commercialized by Nippon Paint Industrial Coatings Co., Ltd. suppress the road surface temperature rise. They also have various other effects, such as improving road durability and sceneries, besides controlling temperature rise.

Suppression of warming

In urban areas, much of the ground and roads are covered with asphalt or concrete pavement. The thermal energy of sunlight absorbed by road surface during the day is released at night, making it difficult for road surface temperature to drop. This is one of the causes of sweltering nights and heat island phenomenon.
The heat island phenomenon and warming temperatures in urban areas are serious problems. According to the Ministry of the Environment in Japan, while the average temperature in Japan has risen by 1.5°C over the past 100 years, the average temperature in Tokyo has risen by 3.3°C, which is about twice as high.

Roads coated with solar heat reflective paints suppress thermal absorption by reflecting infrared rays in sunlight. The rise in road surface temperature is thus reduced by 11 to 14°C during the day in summer, and the amount of thermal release is also reduced at night, therefore it leads to the mitigation of the heat island phenomenon and less use of air conditioners.

Moreover, the effect of the atmospheric temperature reduction in case of 1 m² of solar heat reflective paints is applied is equivalent to circumstances that 35 kg of CO₂ reduced^*1. Therefore, it can promote global warming countermeasures.

*1　In the case that our solar heat reflective paint (U) is used for 10 years
Our estimation is based on H. Akbari, D. Matthews, D. Seto: Environ. Res. Lett. 7, 024004 (2012) (on the premise that the coating film is maintained normally).

Road durability improvement

The solar heat reflective paints also have an effect of reducing road surface deformation by suppressing road surface temperature rise. Heat-sensitive asphalt pavement becomes soft and rutted when exposed to high temperature for extended periods of time. Its deterioration also progresses daily due to weight and friction of vehicles, such as trucks. Our solar heat reflective paints that are made of materials with excellent toughness and flexibility can improve durability of asphalt pavement while maintaining a thermal insulation effect. Therefore, they help extend the life of infrastructure.

Road scenery and safety improvement

In recent years, the needs of road infrastructure for next-generation transportation have been changing, such as zero traffic accidents and coexistence of cars and humans. In response to such changes, we were quick to commercialize coatings that are matched with asphalt appearance and eco-friendly coatings that reduce volatile organic compounds (VOC) emissions. We also provide coatings with color variations, such as blue and red , which can visually express information on traffic divisions and warnings. They help not only to ensure traffic safety but also to create sceneries harmonizing with communities.

The solar heat reflective paints have been increasingly adopted for use on general roads in ordinance-designated cities, such as those in the Tokyo metropolitan area, and have also been increasingly used by companies and facilities on their premises, parking areas, and at commercial facilities in an effort to tackle global warming. The Japanese market for solar heat reflective paints is projected to grow at an average annual rate of about 20%.
Moreover, coating technology will contribute to the realization of a safe automobile society by provided functions such as anti-freezing, improving visibility at night and reduction of repairing by improving pavement durability.

Nippon Paint continues to focus our efforts on promoting the development of eco-friendly coatings that can extend the life of infrastructure and solve social issues in order to realize a sustainable society.

Website of Nippon Paint Industrial Coatings
https://nipponpaint-industrial.com/en/business/heat/index.html