It is understood, people's eyes in the front glass overall transmittance reaches 30%, and the normal environment visibility, able to observe surrounding scenery and ensure driving safety. But in the rain and fog weather and low visibility conditions, even if the standards of the automobile front windshield, visibility is often less than 10 meters, fog and other individual circumstances, even less than 5 meters. So the state generally requires the vehicle to stop in order to ensure the safety of. Filmed glass if visibility is less than 50%, will seriously reduce the driving safety degree.
The vast majority of the automobile front windshield actual transmission rate in 70% - 80%. Because the automobile front windshield is by the superposition of two float glass and a piece of PVB polyester material into three pieces, even if the material is transparent optical grade rate of light transmittance of 92%, transparent overlay the rate of only 77.8%, then a 70% light transmittance of the film stack up, the total transmission rate is only 54.5%. Therefore, when the visibility decreased windshield able to travel the distance of 10 metres to the normal ago, light transmittance is only 50% of the film on the front windshield, but normal visibility less than 1/3, that is to say, the visibility less than 3 meters, the chance of an accident several times the normal transmittance front.
Based on this measure, to ensure that the film can reach the national standard requirements of automotive glass light transmission rate, so the film transmittance should be in 92% above, also is to achieve optical grade transparent in order to meet the requirements. According to experts, the optical transmittance of the films, there are only one or two brands of products.
