Bayer MaterialScience at Fakuma 2012: Sustainable mobility with innovative plastic solutions

The limited availability of fossil resources and the need to reduce pollution are driving the development of alternative drive technologies. Even though there is still no clear trend toward any one future mobility technology, there is a lot that speaks in favor of a more comprehensive use of electric drive systems, not least the support of governments, carmakers and other involved parties.

Bayer MaterialScience sees good prospects for the increasing use of plastics in future mobility technologies, since compared with conventional materials they save weight, increase efficiency and durability and improve appearance. "The proportion of plastics in automotive applications should increase from 15 percent today to as much as 25 percent by 2020," estimates Hans-Peter Neuwald from the company’s automotive team. "It is not just the weight reduction driving this. It is much more the emerging economies playing catch-up in terms of quality, safety and comfort." The use of innovative driver assistance systems, cameras, sensors and products for the protection of pedestrians is another factor favoring the use of plastics.

The trend toward electric mobility, in particular, has given new impetus to automotive lightweight construction. Electric cars have to "slim down" if they are to have sufficient range per charging cycle of the batteries, which continue to be heavy. "We are therefore seeing increased demand for our plastics as alternatives to heavier materials such as steel and glass. This applies to both the production of bolt-on bodywork parts and to interior components, such as fascia and pillar trim," says Dr. Claus Rüdiger, an expert for polycarbonate applications in electric mobility at Bayer MaterialScience.

The use of the polycarbonate Makrolon® in automotive glazing is particularly attractive. This can reduce weight by as much as 50 percent compared with similar glass components. Furthermore, the integration of functions via the injection/injection compression molding process reduces component costs. Entire glazing modules, such as complete tailgates, can now be manufactured to weigh less using Makrolon® and corresponding blended materials.

Current developments are also taking advantage of polycarbonate’s superior thermal insulation properties compared with glass to reduce the amount of energy needed to heat the cabin. This is particularly beneficial with electric cars. They draw their heating energy from the battery, which reduces the vehicle’s range.
Polycarbonate also helps to reduce the weight of automotive headlights. One example are the LED lenses for the low-beams in the headlights of a German luxury sedan. The lenses made of Makrolon® LED 2245 weigh some 50 percent less than if they were made of glass.

Polycarbonate plastics are also well suited for reducing the weight of the batteries in electric vehicles when used as case materials, for example. "We are working on special grades of our Bayblend® FR blends, which play an important role in concepts for flame-retardant, electrically insulating, yet lightweight batteries," says Rüdiger. One useful side effect is that compared with metal, the blends also provide for good thermal insulation of the batteries, ensuring that these continue to function reliably at low temperatures.

Another development focus of Bayer MaterialScience is flame-retardant polycarbonate blends that can be used for the injection molding of dimensionally stable, low-distortion frames for the cells of lithium-ion batteries. These materials also have good prospects for use in other assemblies in the electric drive system, such as components for the battery management system and power electronics that are in contact with live parts.

Bayer MaterialScience is not concentrating just on automotive lightweight construction and battery technology for its material solutions, however. Rather, the company’s holistic approach also calls for the plastics to be produced with maximum energy and resource efficiency.
One example are the Makroblend® GR blends. They are formulated with single-sort polyethylene terephthalate (PET) and polycarbonate obtained from sorted commercial water bottles. The performance profile of the blends is on par with that of conventional virgin material. These blends are ideally suited as an alternative to steel sheet and aluminum for the production of weight-saving automotive bodywork components such as trunk lids and skirts, spoilers, covers for convertible top compartments and antennas.

Another attractive field of application for polycarbonate and its blends as well as for polyurethanes are charging stations for electric vehicles. The widespread availability of charging stations is a prerequisite for the broad adoption of electric mobility. "We have developed a variety of materials for charging station housings, some of which have already proven effective in volume production," says Dr. Berit Krauter, who is in charge of this polycarbonate application. In addition to high flame-retardance and electrical insulation, the housings are characterized primarily by good mechanical performance and high impact strength, which protects them against vandalism.

Source: Bayer MaterialScience