A heat-absorbing panorama roof made of shatterproof polycarbonate brings more light into the interior and creates a sense of greater spaciousness in the smart fortwo
Webasto is manufacturing the fixed panorama roof for the third generation of the smart fortwo. The 1.2-square-meter, transparent roof panel is made of the lightweight material polycarbonate (Makrolon® from Bayer MaterialScience). The roof system admits a lot of light into the interior, creating a pleasant, generous sense of space for the passengers. Visually, it is a perfect extension of the front windshield.
Milestone in comfort due to infrared absorption
The technical highlight of the roof system is its ability to absorb solar energy and thus prevent the interior from heating up too much. In a nutshell, the IR rays stay where they belong: outside. This is made possible by infrared absorbers integrated into the polycarbonate – more specifically, into the granules the panels are made of. The product Makrolon® AG2677 in the color and temperature-stable, heat-absorbing color 771079 is being used on the new smart for the first time.
The infrared absorption is also beneficial from an ecological point of view. If the interior doesn’t heat up as much, there is less need for cooling from the air-conditioning system. And this reduces fuel consumption. With this innovative roof, Webasto and Bayer have reached another milestone in passenger comfort.
Around 50 percent lighter than glass
The material is extremely impact-resistant, weatherproof and lightweight. A roof made of polycarbonate can be up to 50 percent lighter than a glass equivalent. The plastic panel on the new smart fortwo weighs only 9.8 kilograms. Due to the low weight, not only is the fuel consumption of the small city car reduced, the roof also has a positive influence on the driving dynamics, as it shifts the vehicle’s center of gravity further down.
The roof is manufactured by means of two-component injection-compression molding. Besides the transparent Makrolon® AG2677, the black-colored polycarbonate ABS blend Bayblend® T95 MF is used as the second component. It enables the integration of additional functions such as screw bosses on the bottom side of the roof. Attached to them is the infinitely adjustable fabric roller blind used to control the brightness of the interior.
A coating layer makes the panorama roof resistant to scratching and weathering influences. The roof system is the world’s largest injection-molded, transparently coated car roof with an infrared absorber.
Webasto manufactures the polycarbonate roofs in its own lightweight competence center in Schierling near Regensburg. Bayer MaterialScience supports its customer in the development of this roof with a complete service package for automotive glazing, consisting among other things of simulation calculations for the mold filling and thermal expansion, material development and selection, testing technology and analytics, as well as process technology.
