Federal regulations prohibit the use of polycarbonate in an AS1 position (windshield). Federal regulations further state, for these positions must demonstrate the ability to meet ≥ 70% Light transmission (LT) for AS1 (Windshield) and AS2 (Sidelites) applications. In 2005, the U.S. Dept. of Transportation’s National Highway Traffic Safety Administration (NHTSA) confirmed that polycarbonate may be used in vehicle areas specified for Item 2 (AS2, AS3) glazing (safety glazing material for use anywhere in a motor vehicle except windshields), provided that the product satisfies the existing performance standards for Item 2 glazing. Questions persist regarding retention of the necessary transparency over the useful lifetime of the vehicle. A test has been developed for coated polycarbonate automotive glazing to measure their resistance to windshield wipers. This test enables simulation of the actual stress exerted on the wiped glazing far more realistically, accurately, and with a higher reproducible quality than is possible with the Taber abrasion test stipulated in the regulations. Initial tests have shown that, when dirty panes with a polysiloxane coating are wiped under primarily wet conditions, they exhibit virtually no clouding that is visible to the naked eye - even after 30,000 double-wiper cycles.
Wiper performance is critical in the design, engineering, and testing acceptance of a windshield for a saleable vehicle.
PC glazing technology continues to enable the development of advanced, lightweight window designs for the automotive industry.