Plastics use in cars rises as emissions laws get tough

A smaller footprint

03 September 2008 17:48  [Source: ICB]

The use of plastics in car manufacturing is accelerating as the automotive industry gears up to meet new emissions regulations

New European legislation such as Euro 5 and 6, as well as EPA 2010 in the US, are applying stricter rules to reduce carbon dioxide (CO₂) emissions from new cars.

These requirements pose an enormous challenge to carmakers, who are turning to the plastics industry to help create lighter vehicles and improve fuel efficiency. Generally accepted industry estimates are that 6-10% of weight reduction equals a saving in fuel efficiency of 5-7%.

Using plastic in cars is certainly not new. We are all used to seeing plastic dashboards, fenders, and headlamps, but new applications externally, internally and even under the hood are growing, as plastics producers and the car industry become more innovative.

Take glazing, for example. Major strides have been made in using polycarbonate (PC) in automotive glazing, and early problems with abrasion and scratch resistance have been resolved.

Original equipment manufacturers (OEMs) are now supplying PC windows to car manufacturers, and seven models on the road today have PC windows. These include Germany-based Daimler's Smart car, Japanese carmaker Honda's Civic and the Corvette, made by General Motors, of the US.

Derek Buckmaster, global market director, body panels and glazing, for Netherlands-based SABIC Innovative Plastics, Automotive, says: "There are at least six companies supplying PC windows worldwide today. As more OEMs qualify their specifications for PC windows, capacity will grow." He reveals that SABIC Innovative Plastics is working with 15 OEMS around the world to complete technical specifications.

German polymer major Bayer MaterialScience says that by substituting PC for glass in sunroofs, the weight of the roof can be cut by 30-40%. That also reduces a car's center of gravity, which improves handling and makes it less vulnerable to rolling.

Volkhard Krause, global head of the automotive glazing team in Bayer MaterialScience's PC business unit, says: "There is a move to use more and more transparent roofing systems, and PC gives designers much more freedom than glass."

Innovative designs in PC include large, panoramic roofs, such as that used in the Smart Fortwo.

For large panoramic roofs, three-dimensional styling can be realized by using PC, a feat not possible with glass. Roofs of 1.2m² (12.9ft²) are already being produced, and Krause believes that even larger roofs are feasible, up to 1.7m² and even possibly up to 2m². "We are carrying out tests to see what the limitations are for PC," he says.

Bayer MaterialScience has also developed a completely transparent and highly integrated, lightweight lamella roof based on PC as an alternative to conventional sliding and folding roofs. The roof's special feature is that it incorporates transparency, sealing, and opening and closing functions, in a single plastic component that can be manufactured in just one step.

Wrap-around windows that integrate various functions in the glazing component such as lenses, antennas, pockets and door handles are another possibility.

Double-curved glazing, where applications include integrated spoilers, and merging taillights into tailgates, is also another key design trend.

But, PC for use in front windshields is still a wish rather than a reality for plastics producers, although a change in regulations could boost demand for this application sooner rather than later.

Buckmaster says that an amendment to European regulation ECE43R, which would allow PC to be used in front windshields, could be passed within the next 12 months. PC is currently used for front windshields in racecars, and Buckmaster expects this trend to move to standard vehicles in the long term.

PLASTIC INTEGRATION

Krause estimates that demand for PC in glazing could rise to around 100,000 tonnes/year in 10 years. Current consumption is 3,000 tonnes/year.

The car's interior has largely been conquered by the plastics sector, and the exterior is now also well supplied by the plastics industry. Polypropylene (PP), for example, is used in body panels, fenders, tailgates and hoods, and innovative exterior products are still being developed.

German carmaker BMW hit industry headlines in 2006 with its novel PP-based fender on the X5 model. It was the world's first fully integrated fender module, incorporating several parts and functions, such as headlamp reinforcements, wheel housing, cleaning systems, airbag sensors and cooling devices. It was also 50% lighter compared to traditional steel components.

Franz Zangerl, business development manager, automotive, at Austrian polymers producer Borealis, says that about 15% of the average-sized family car is now made out of plastic. This compares to about 6% 20 years ago.

"Growth has accelerated in the last 10 years," says Zangerl adding that PP-based materials account for 60-70% of overall plastic used in cars today. Other materials include polyurethanes (PU), PC blends, polyamide, and acrylonitrile-butadiene-styrene (ABS).

The structural part of a car is the next hurdle for plastic makers to clear. Steel is still mostly used, but glass-reinforced PP is a good fit, says Zangerl.

He says that spaceframe technology, being used on cars such as the Smart, where a metal frame is clad in plastic, is an interesting innovation that could have good potential in the future.

Ralf Seufert, vice president, global sales and marketing for Quadrant Plastic Composites (QPC), a Swiss-based manufacturer of glass mat thermoplastics (GMT), is seeing strong growth for GMT as a replacement for steel in structural applications.

"Composites have huge potential in various structural uses, such as front-end carriers, modules and crash structures, and body-in-white applications [sheet-metal body parts before components/trim have been added]," he says.

QPC has introduced a new high-performance composite front end and is working on hybrid crash structures. The hybrid material is GMT-reinforced with steel cords and designed for use in high-demanding applications where safety is paramount.

Seufert says there is a big focus on taking weight out of the vehicle's structural parts because this is where the most weight-saving potential lies. Some OEMs are also looking at composites to improve aerodynamics, for instance, by fitting closed underbodies that boost fuel efficiency and reduce greenhouse gas emissions.

Closed underbodies, where an engine shield is fitted along the underside of a vehicle, have been used for many years in sports and premium cars but are now a must for standard cars, says Seufert.

At present, about 3% of a car is made from composites, but Seufert believes this could rise to 8-10% in the future.

UNDER THE HOOD

As cars get lighter, so engines are getting smaller - and hotter. Netherlands-based life sciences and materials sciences company DSM says that the past 10 years have seen a new generation of vehicles with smaller engines and higher turbo pressure, and this will continue in the coming decade.

This development has led to less space under the hood and higher temperatures, with components such as air ducts and air intake manifolds exposed to continuous temperatures of 210˚C (410˚F) and higher.

Buckmaster says there is enormous potential under the hood for plastics. As the industry moves to using more diesels, hybrid vehicles, turbo systems and even electric-only cars, there are more opportunities for plastics to be used in parts such as covers, trays, ducts for air and water, and enclosures for electronics and control systems.

PLASTICS PLAY TO EFFICIENCY

"Under-the-hood applications are changing dramatically. The focus is moving away from power, to efficiency," says Buckmaster.

Although plastics producers are upbeat about the possibilities for plastics in cars, it has been an uphill struggle to get car manufacturers to pay attention.

It is only the threat of impending legislation, and punitive fines if they fail to comply, that are forcing many car companies to reconsider their production focus.

"I have not had my door beaten down yet by car companies, but we've had many, many requests for information about using plastics to reduce weight in the last 12 months," Buckmaster says.

Plastics producers say that for many years, car companies have not recognized plastics' potential, and they have been hesitant to implement a plastic component if it is not cost competitive. In addition, car companies felt outside their comfort zone when faced with plastic. Comfortable with working in steel and aluminum, designers did not have the technical knowledge and experience to understand or work with the opportunities afforded by plastics.

This is changing, as is apparent from the many concept cars unveiled over the past couple of years by car manufacturers collaborating with major plastics companies. These include South Korea's Hyundai with Bayer MaterialScience, and the UK's Land Rover with SABIC Innovative Plastics.

The biggest trend now for carmakers centers on sustainability, as consumers demand cleaner transport. Whether this comes in the form of using green materials, making smaller cars or using alternative power, it is clear that car manufacturers are starting to embrace new materials and technologies, which can only be a positive move for the plastics industry.

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By: Elaine Burridge
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