Laminated windscreen is made by sandwiching a layer of polyvinyl butyral (PVB) between two pieces of glass. The glass and the PVB are sealed by a series of pressure rollers and then heated. This combination of pressure and heat chemically and mechanically bonds the PVB to the glass. That inserted layer of PVB is what allows the glass to absorb energy during an impact and gives the glass resistance to penetration from flying projectiles. It also deflects up to 95 percent of ultraviolet (UV) rays from the sun. Laminated windscreen can break and be punctured, but it will stay intact because of its chemical bond with the PVB.
The strength of laminated windscreen allows it to perform two very important safety functions in cars. First, it allows passenger side air bag to deploy correctly. Driver's side air bags tend to fly straight toward the driver from the steering wheel, but when the passenger air bag is deployed, it bounces off the windscreen toward the passenger. An air bag deploys with incredible speed --1/30th of a second -- and can withstand 2,000 pounds (907 kilograms) of force. The windscreen has to absorb both the speed and force of the air bag in order to protect the passenger in an accident. Because of its strength, laminated windscreen can keep occupants inside the car during an accident. In the past, occupants could be ejected through the windscreen because the glass wasn't strong enough, but today's windscreens provide more security.
In addition to absorbing the force of deployed air bags and keeping passengers inside the vehicle, laminated windscreens also provide strength to a car's roof. The windscreen provides a significant amount of strength to the structural support in the cabin of the vehicle. For instance, in a front end collision the Windscreen provides up to 45% of the structural integrity of the cabin of the vehicle and in a rollover, up to 60%. How would you like for over half of the force of a collision to be absorbed by YOU because your Windscreen flew out in an accident? It happens more times than most of us are aware. It's important to your family's safety that the replacement windscreen in your vehicle is meet the safety standards and installed properly.