BASF Pioneers Weight Reduction with the Use of Natural Fibers

BASF has pioneered the use of natural fibers in automotive interiors for the purpose of weight reduction. The company worked with Germany-based International Automotive Components (IAC) to make the  FiberFrame natural fiber sun roof frame for the 2017 Mercedes-Benz E-Class. This is the first automotive roof frame that has been made entirely of nonwoven natural fiber composites. BASF’s proprietary innovation is made of 70% natural fiber and can help save upto 50 when it comes to weight, as compered to conventional metal-reinforced sun roof frames.

In the EcoMatHot natural fiber-based prepreg, which IAC specifically developed for this application, the fiber mat is impregnated with an acrylate-based resin matrix, called Acrodur 950 L that was provided by BASF. Acrodur is a water-based, formaldehyde-free, one-component system and its underlying technology is based on the thermal crosslinking of polycarboxylic acids with a multi-functional alcohol.

Unlike classical two-component reactive resins, no organic substances, like asphenol or formaldehyde  are released during the crosslinking process and the only by-product of cure is water. According to Henning Karbstein, manager for new business development and idea management at BASF’s dispersions and pigments business in Charlotte, NC, US, during processing, Acrodur 950 L thermoplastic crosslinks to a thermoset polymer during the polycarboxylic acid phase under heat. This creates a strong bond between the Acrodur molecule and the fiber and thermoset. As Acrodur is water-based, it easily takes on additives like colorants or flame retardants. The fiber mats are dried after impregnation with a conventional convection oven or with radio frequency drying techniques. IAC then receives the prepregged fiber mat, which is still soft and flexible and the frame is then manufactured in-house by IAC in a hot molding process.

IAC director of advanced engineering Fritz Schweindl said that the natural fiber components that are strengthened with Acrodur are ideal to mold as they are environmentally friendly and save time during the production of the composites. The product is also safer to work with as it is low in emissions.

IAC started production of FiberFrame in November 2015 at its Center of Excellence for overhead products in Prestice, Czech Republic, to support the Mercedes-Benz E-Class launch. IAC also manufactures the headliner, the outer-rear wheel house liner, inner wheel house cover and rear seat cover for the vehicle. According to BASF, with Acrodur it becomes possible to turn natural fibers into functional and environmentally friendly materials. This makes it a natural choice for molded parts made from natural fiber and post-moldable nonwovens.

Unlike other high-strength natural fiber-compatible resins, like MDI resins, urea formaldehyde (UF) and phenol formaldehyde (PF), which are normally used for wood and cellulose fiber bonding, Acrodur does not emit harmful VOCs during production, handling or use. Hence, it is highly suitable for safe applications in the automotive interiors.

Automotive manufacturers have been increasingly using nonwoven fiber composites, mostly natural fiber/PP and glass/PP as they perform better than simple injection molded plastics. In addition to the benefits with regard to sustainability, the use of natural fiber composites make a significant difference in terms of weight reduction and performance. Acrodur-based nonwoven composites which are made mostly with natural bast fibers enhance mechanical performance by about 20 per cent.