Modern buildings use a large number of thin and transparent exterior materials such as glass and plastic. While improving indoor lighting, these materials inevitably cause sunlight to enter the room, causing indoor temperature to rise. In summer, as the temperature rises, people generally use air conditioners to cool down to balance the indoor lighting caused by sunlight. This is also the main reason for power cuts in some areas of our country in summer. The increasing popularity of automobiles has led to increasing common consumption in summer for lower interior temperatures and lower air-conditioning energy, as well making thermal insulation films for automobiles. Others, such as the transparent heat insulation of the heat-insulating and cooling plastic daylighting panels of agricultural greenhouses, and the light-colored heat-insulating coatings of outdoor shade tarpaulins, are also developing rapidly.
At present, the most effective method is to add nanoparticles with the ability to absorb infrared light, such as antimony-doped tin dioxide (nano ATO), indium tin oxide (ITO), lanthanum hexaboride and nano-cesium tungsten bronze, etc., to the resin. Make a transparent heat-insulating coating and apply it directly to glass or shade cloth, or apply it to PET (polyester) film first, and then attach the PET film to glass (such as car film), or make it into a plastic sheet, such as PVB, EVA plastic, and these plastic sheets and tempered glass compound, also play a role in blocking infrared, so as to achieve a transparent heat insulation effect.
To achieve the effect of coating transparency, the size of the nanoparticles is the key. In the matrix of the composite material, the larger the size of the nanoparticles, the greater the haze of the composite material. Generally, the haze of the optical film is required to be less than 1.0%. The visible light transmittance of the coating film is also directly related to the particle size of the nanoparticles. The larger the particle, the lower the transmittance. Therefore, as a transparent thermal insulation film with higher requirements for optical performance, reducing the particle size of nanoparticles in the resin matrix has become a basic requirement for improving the performance of the coating film.