The "NCV (Nano-Cellulose Vehicle) Project" of Japan's Ministry of the Environment developed a "sports car made of cellulose nanofiber (CNF)."
The project is aimed at replacing auto body parts, which are made mainly of steel materials, with CNF-based parts as much as possible. One of the targets is Toyota Motor Corp's "86" compact sports car. The commercialization of CNF, which is a new light-weight, strong material made of wood, is accelerating in the field of automobiles.
The newly-developed CNF-based parts include a front hood, trunk lid, roof side rail, seat back, intake manifold, door trim and engine cover. Especially, the front hood and trunk lid, which are large-size parts, drew our attention. They are difficult to be formed into shapes and require new production technologies. The reduction of their weights has a great impact.
40% lighter front hood
The CNF-based front hood was developed by Yuji Kageyama, professor at the Graduate School of Engineering, Kanazawa Institute of Technology. Its mass is 8kg, which is 40% lighter than the mass of the current steel front hood (14kg).
The CNF-based front hood has a three-layer structure, in which a foamed polyurethane layer (core material) is sandwiched between inner and outer coats. The thickness of the foamed polyurethane layer is about 10mm while the inner and outer coats are 1mm in thickness, respectively (total thickness: about 12mm).
CNF was used for the inner and outer coats. Each of them has a two-layer structure consisting of kenaf nonwoven fabric (on the side of the foamed polyurethane layer) and CNF paper. The kenaf nonwoven fabric and CNF paper were attached to each other by using epoxy resin.