Modern car interiors are dominated by plastics. For cost reasons, small cars, in particular, often contain parts made of polypropylene, which scratches easily. However, if GENIOPLAST® Pellet S – a silicone additive from WACKER – is added to the plastic, there is a good chance that its surface will maintain its appearance even after long and intensive use.
Nowadays, an automotive interior should be comfortable, which is why plastics with a high-quality finish are used.
Buying a car is a highly emotional affair. The buyer first looks for an attractive exterior design and then focuses on the car’s interior. People spend so much time in their cars nowadays that the interior needs to be comfortable and have a high-end look and feel. In upper midsize and full-size cars, manufacturers rely on elaborately foamed and decorated plastics or expensive materials such as leather and burl wood to achieve the optical and haptic qualities desired by customers.
The lower down potential buyers move in the model hierarchy, however, the more price conscious they become. The car interior is one of the few areas where manufacturers can cut costs without compromising functionality or safety. That’s why, for the interior trim of compact and small cars, they use many parts based on materials which are considerably less costly to make – talc-filled polypropylene, for example, is the cheapest plastic suitable for interior applications. Parts made of this plastic material scratch easily and can quickly become unsightly in use. That’s why automakers are looking for cost-effective ways of giving the polypropylene parts a surface that keeps its high-quality and attractive appearance.
Foamed plastics and imitation leather finished with additives ensure that the appearance and texture of a car interior convey the desired high quality.
Matt and Reflection-Free
Interior plastic parts made of talc-filled polypropylene are hard and their surface looks matt. Typical examples include the lower part of the dashboard, the glove compartment’s cover, the panels below the door handle, the pillar trim and the housing of the center console. The surface is matt for several reasons, as Dr. Michael Geck, applications engineer for WACKER’s plastic additives segment, explains: “Matt plastic surfaces have a velvety feel, look good and avoid light reflections that could irritate or dazzle the driver.”
However, the more matted such surfaces are, the more susceptible they are to scratches and abrasion. For example, sharp-edged ignition keys can quickly leave shiny scratches when they scrape a polypropylene dashboard. Even blunt objects can leave traces. Running a fingernail over the matt plastic surface produces a shiny streak – the nail polishes the surface. Experts refer to this as mar resistance or marring. If your knee repeatedly rubs against the same section of a door panel when you get in and out of a car, you will leave a mark – the affected section of the surface will look worn. Plastics processors have at their disposal numerous methods that give inexpensive plastic a high-quality look. They can, for example, back-foam the hard material, coat it with a thermoplastic elastomer, paint it or decorate it with hot stamping foils. However, all of these methods make the parts considerably more expensive.