Lightfast thermoplastic polyurethane for car interiors: Playing with colors Coating for industrial fabrics and thermoformable ABS sheets
Leverkusen - Light colors are a major trend for car interiors, particularly for many plastics used for the instrument panel, central console or door panels, for example. To prevent unattractive discoloration appearing over time, they must not yellow under the influence of UV light. For coating industrial fabrics, non-woven materials and interlaced yarns in particular, Bayer MaterialScience AG has developed new grades of the thermoplastic polyurethane (TPU) Desmopan® that remain lightfast throughout the car's lifetime and can therefore be dyed any color. The TPU grades are also suitable for applying a thin, colored soft-touch surface to thermoformable ABS semi-finished products by coextrusion.
"We see potential applications in fabric coating for trunk floor mats, rear shelves and door and other trims, for example. The composite of fabric and TPU can be back-injected, back-compression molded and back-foamed which opens up a wide range of applications," says Jens Ufermann, Segment Manager of the TPU Business Unit at Bayer MaterialScience. The soft-touch-coated ABS semi-finished products can for example be processed into components for the instrument panels of commercial vehicles, automobile campers, tractors and fork lifts.
"Our aliphatic TPU materials are already proving to be extremely lightfast in practice in various instrument panel skins produced in large volumes using the powder slush method. The skins have passed all the relevant tests for lightfastness by the automobile manufacturers," says Ufermann. Another advantage of TPU as a coating material is that it demonstrates better mechanical properties and is more resistant to scratching, tearing and abrasion than polyolefins and PVC, for example. It also adheres well to many materials.
Fabrics can be coated with the plasticizer- and halogen-free Desmopan® versions using calendering, extrusion and powder molding techniques. A progressive build-up is also possible using coextrusion without significant outlay. For instance, an aromatic TPU can be applied first as a cost-effective base material, followed by a light colored top coat made of aliphatic TPU.