Japan’s Teijin Limited has developed a formable gasoline-resistant film made of Planext bioplastic to replace chrome plating. Parts maker Honda Lock Mfg. has adopted the film for nonconductive door handles integrated with smart-entry systems. Planext is an eco-friendly bio-polycarbonate made with bio-content based on isosorbide from corn-starch and other plants.

Teijin developed the film using a special metal-evaporation technology from a processing-manufacturer partner. Teijin is currently developing other automotive applications in addition to mass producing the film for door handles.

This new film is made with Planext SN4600, an improved grade of Teijin’s Planext bioplastic. In addition to original Planext grade properties such as chemical resistance, transparency and surface hardness, polymer reforming is employed to confer Planext SN4600 with important new properties including gasoline resistance, formability, and UV resistance.

Teijin’s gasoline-resistant film is reportedly ideal for vehicle doors, which of course can potentially come into contact with gasoline. Further, optimized heat resistance and film forming technology enable high formability for fashioning into complicated shapes. In addition, UV protection helps to shield the base material and prevent discoloration.

Vehicle door handles are increasingly being integrated with secure smart-entry systems that enable the doors to be locked and unlocked by simply placing one’s hand on a handle sensor. The material surrounding the sensor, however, must be nonconductive to avoid sensor malfunctions, so conventional door handles made of electroconductive chrome plating coated on a resin base are not suitable. Conventional plastic films made with a metal-evaporation process are nonconductive and are already being used as metal substitutes for automotive exteriors, but they are not suitable for door handles because they are neither gasoline-resistant nor highly formable.