Plastics Innovations for the Interior

Renewable raw materials, special visual effects, recycled materials, light integration and lightweight construction: these are five trends at K 2025 that will influence car interiors. The trends could be seen live at the trade fair.

A visible part for the vehicle interior: this is still an eye-catcher for the stand at a plastics technology trade fair and a challenge for the entire production process chain. It becomes even more challenging when natural fibers are integrated into the material matrix.

A successful example was on display at the Wittmann stand: an interior cladding based on the long-fiber-reinforced composite material NFPP - a combination of natural fibers (NF) such as flax or kenaf with polypropylene (PP) - with a cover film.

Lightweight Construction and Special Look with Natural Fibers

Under heat and pressure, a resilient matrix with visible natural fibers is created in less than 65 seconds. The PP part of the film melts and the fiber structure becomes visible. This creates an exciting look, an organic feel and stability with a low weight. A semi-transparent look is also possible, and further processing steps such as clear varnishing or impregnation can be dispensed with.

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The components are up to 40 percent lighter than comparable all-plastic solutions, offer additional sound and heat insulation and can be fully recycled if the right materials are selected. A production-ready component was presented at the trade fair as a joint project between Wittmann (turntable injection molding machine and automation), Frimo (tool), Kurz (cover film) and Polyvlies (NFPP fiber mat).

Recyclates: PCR for the Interior

One of the central exhibits at the Pöppelmann stand was the carrier for a center console with a 55% recycled content. This alone is not unique, but the fact that this interior component is made from post-consumer recyclate (PCR) from the Yellow Bag is. Because the PP recyclate is processed using the MuCell foaming process, the component is extremely lightweight. Matthias Lesch, Managing Director of Pöppelmann: "The combination of lightweight construction and PP recyclate is very interesting for the industry."

When developing such components, Pöppelmann benefits from its extensive experience in the processing of recycled materials. This also includes the simulation of processing procedures. Over the past ten years, Pöppelmann has built up a large database that simulates the behavior of various recyclates during injection molding with the addition of nitrogen (MuCell). According to Matthias Lesch, this has also proven to be a good investment in the future with regard to the EU End-of-Life Vehicle Regulation (ELV).

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Good Feel, Soft Touch

Among other things, Asahi Kasei presented a thermoplastic styrene block copolymer (SEBS) in Düsseldorf for interior surfaces that require a good feel and a soft touch. Here, too, the user is offered an advantage in terms of recyclability: The PP carrier of the component is bonded to the foam without any adhesive. This is possible because the surface, foam and carrier layers are not made of different materials, but of the new SEBS material, which is formed in a core-back injection molding process.

Thanks to the strong chemical bond between all layers, no additional adhesive layers are required. This provides the user with a new and significantly more recyclable material for the production of door panels, armrests or center consoles.

Deep Black as a Design Statement

Kurz used the example of the newly developed coating technology "Deep Black Surfaces" to show how surfaces of control elements and screens can be designed in a particularly intense, non-reflective deep black and offer a high-contrast look. In-mold decoration (IMD) is used to produce plastic components that can be seamlessly combined with anti-reflective glass elements.

The surfaces of infotainment displays, for example, are therefore easy to read even in direct sunlight. The surface is characterized by durability, scratch resistance and chemical resistance. At the same time, the IMD process used improves the CO₂ footprint thanks to thin-film technology and realization in a single, highly efficient process step and enables the design of recyclable components.

Metal Look with Depth Effect

Anyone driving a BMW iX in the "China version" will find crystal-like controls on the steering wheel, which sparkle metallically in the blue-grey spectrum depending on the incidence of light. The symbols for telephone, audio etc. are easily recognizable during the day and backlit at night.

KH (Kunststoff Helmbrechts) developed the control elements with this effect and presented them at the K 2025. The metal indium, which is applied to a film as a 1 to 2 µm thin PVD coating and covered with a thicker PC layer, provides the shine. Indium was chosen because this metal shines in a similar way to chrome and - with the right molecular density - is suitable for capacitive operation. It also enables exciting optical effects through colored back printing.

The series application for the BMW iX is highly complex: the film is supplied as a semi-finished product with an indium coating and several color layers. At KH, a black print is added to block out the light. The film is formed, punched, inserted and overmolded with PC. A laser then removes the entire coating - color and indium - so that only the transparent PC remains, but is not affected. The symbols are then backed in white and the front side is coated with a UV scratch-resistant varnish. Glued onto the corresponding sensor technology, the result is a complete and very stylish control element.

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Transparent Polymers for Screens

Touch controls, head-up displays, ambient light: there are more and more applications for transparent plastics with a defined property profile in vehicle interiors. Asahi Kasei has developed the new optical polymer AZP, which is characterized by almost zero birefringence and low weight, especially for head-up displays and data or, more precisely, AR/VR glasses.

According to the manufacturer, it overcomes the challenges of conventional transparent polymers in applications with polarized light: The material enables a clear and uniform display.

At the same time, it offers excellent processability for the large-scale production of injection-molded optical components. The company presented an interactive head-up display application at K. And to complete the picture of the K-2025 exhibits for the interior, new interpretations on the subject of "plastics and light" were also on display at some stands.