Two generations of MINI in front of the BMW museum

© BMW Group

Two success stories rolled into one

A small car has been a huge success for decades: the MINI. For over 15 years, high-gloss, non-transparent PLEXIGLAS® pillar posts have contributed to the cult car’s unmistakeable design.

For many people, cars are much more than a means to an end, they are status symbols or even an expression of the owner’s personality. MINI was seen as a lifestyle brand as far back as the 1960s. It was chic, extrovert and different. Even pop stars like the Beatles had their photos taken in the MINI. So the little car’s characteristic design, meant to appeal to potential buyers, has basically remained unchanged. Big round eyes, a chrome-plated radiator grille and a large front windscreen make sure you can always tell a MINI when you see one.

Behind the scenes at the assembly line

Automobile manufacturers, direct suppliers and materials manufacturers work together closely in today’s vehicle assembly processes that are based on the division of labor. The first nontransparent, high-gloss add-on car body parts made from PLEXIGLAS® ready for serial applications were created in cooperation with several companies. The product was developed with direct feedback from the processing company, the machine manufacturer, the toolmaker and the end customer (BMW). This was and remains an important foundation for success.

The vehicle’s appearance has nevertheless evolved in several stages over the past decades. The biggest change in the brand came in 2001, when it was relaunched by the BMW Group. For the brand’s relaunch, the BMW Group revamped the entire car and transformed it into a premium brand. In its modern incarnation, the MINI became much bigger, with a raft of new technology, noble trim and a high-class look. Its designers chose materials that would underline the car’s premium character, such as high-gloss elements to create a harmonious appearance.

Glass-like material

Prior to the relaunch, the A-pillar posts of the MINI that frame the sides of the large front windscreen were made of metal and painted in the same color as the car. But that created an optical break. The revamped version took a different approach – a highgloss pillar post in piano black that looked like glass and made the front windscreen appear bigger still. This design was enabled by PLEXIGLAS®, known by its chemical name polymethyl methacrylate (PMMA).

“Our high-gloss material creates a very classy appearance similar to glass, which far outshines coated surfaces.“

Tony Halbländer
Senior Technical Marketing Manager at Evonik

High-gloss Class A surface

The trademarked PMMA from Evonik provides high-gloss Class A surface with great depth of color combined with toughness. “Our high-gloss material creates a very classy appearance similar to glass, which far outshines coated surfaces. These never appear entirely smooth, whereas the injection-molded pillar post is wellnigh perfect,” explains Tony Halbländer, Senior Technical Marketing Manager at Evonik. He was the PLEXIGLAS® project manager responsible for introducing the component to the MINI. The glass-like surface appearance stays the same in the long term, because PLEXIGLAS® is resistant to fuels and chemicals, as well as having excellent resistance to UV light and weathering. That means the material looks as good as new even after many years of exposure to all winds and weathers. Evonik recently confirmed this in a laboratory weathering test. Compared with other plastics, the optical appearance of PLEXIGLAS® remains virtually unchanged over the entire service life of a vehicle.

One-step manufacture

“Our non-transparent add-on car body components made of PLEXIGLAS® 8N molding compound in the special color 9V022 were a real innovation in the early 2000s,” Halbländer recalls. Before this new molding compound was developed, pillar posts were usually made from metal or plastic and then given a highgloss coating. “But coating components is very time-consuming,” Halbländer explains. “Automobile manufacturers can dispense with this step by choosing car body parts with molded-in color, made of PLEXIGLAS®.” These parts are injection-molded in just one operation and are ready for use almost straight away. An economic solution that reduces the cost of components by up to 40 percent.

Zeichnung eines Kühlergrills

New molding compound for tougher components

There is a continuing trend towards high-gloss black automotive components. In response, Evonik has developed a new specialty molding compound: PLEXIGLAS® Hi-Gloss NTA-5 offers much higher impact strength combined with a high heat deflection temperature under load. This product is suitable for applications that call for greater resistance to stone chips, e.g. radiator grilles and mirror housings.

© Evonik

Trend is catching on for more and more vehicle parts

MINI too has relied on the combination of cost-effective production and a high-class appearance for over 15 years. “The A-pillar posts in the MINI were our first serial application for highgloss add-on car body components made of PLEXIGLAS®,” Halbländer says. Over three million MINIs have rolled off the assembly line since then, all with the same PLEXIGLAS® A-pillar post on board. Following the first generation of the new MINI in 2001, fourteen other variants of the classic have been launched on the market, such as the popular Clubman. As the MINI family grew, the fields of application for high-gloss PLEXIGLAS® panels have grown with them. “It all started with the A-pillar post, but now these components can be found all over different models of the MINI,” says Halbländer. Since the 2007 facelift, the C-pillar panel, which is much larger than in previous models, has also been made from the Evonik product. In the MINI convertible, the windscreen member is finished off at the top with a panel made from the trademarked PMMA.

“But the components made from our material are not just used for decorative trim.”

Tony Halbländer
Senior Technical Marketing Manager at Evonik

Acrylic weighs less than metal

“But the components made from our material are not just used for decorative trim,” Halbländer points out. “They also have a functional purpose in some vehicle models.” They act for example as window track guides in B-pillar posts, where their glass-like appearance makes the windows look bigger. The benefit that all PLEXIGLAS® components have in common is invisible, though: the trademarked acrylic weighs less than metal, which helps reduce vehicle weight. That is an important aspect given the trend towards electromobility.