Editor's note: This story is part of the WardsAuto digital archive, which may include content that was first published in print, or in different web layouts.
KARIYA, Japan – Toyota Motor Corp.’s two newest hybrid cars, the Sai and Lexus HS 250h, have turned decidedly green in their use of eco-friendly materials.
The auto maker’s main interior supplier, Toyota Boshoku Corp., outfitted each model with more than 10 lbs. (22 kg) of components made from plant-based composites – mainly kenaf, a fiber indigenous to Southeast Asia, mixed with polypropylene, a widely used thermoplastic.
Special components developed for the HS 250h and Sai include trim for the cowl, door and trunk, pillar garnish, package tray and sun visor and ceiling materials. The supplier estimates 30% of trunk and interior parts are made from plant-based materials.
In addition, Toyota Boshoku now mixes castor oil, a vegetable oil, with polyurethane, a petroleum derivative, to make seat pads. The castor oil penetration stands at 15%.
“Our strategy is to be carbon neutral,” says Toyota Boshoku research executive Yasushi Nakagawa. “Where possible, we use plants which do not emit (carbon dioxide) into the atmosphere.”
According to Nakagawa, plant-based materials have a second advantage: reducing component mass and weight.
The research executive, who heads Toyota Boshoku’s new Sanage Research and Development Center near Toyota City, estimates weight reduction through use of kenaf-based composites – both kenaf and polypropylene and kenaf and polylactic acid composite – to be about 35% compared with conventional plastics.
Related document: Select Vehicles Using Kenaf-Based Components
The supplier introduced its first plant-based component in 2000 with the door trim for the LS 430 luxury sedan, predecessor to the current LS 460.
Since then, Toyota Boshoku has supplied 13 Toyota and Lexus cars and one Suzuki Motor Corp. model, the APV minivan built in Indonesia, with plant-based door trim, seat-back boards and package trays.
The supplier annually consumes 3,000 tons (2,700 t) of kenaf fiber in component production.
Nakagawa admits the material remains relatively expensive. The fiber, after being harvested, must be mixed with polypropylene or polylactic acid fiber to make a mat, then heat-treated and pressed into a board before being molded into the component.
By expanding sales beyond the Toyota group and improving economies of scale, costs will come down close to conventional materials, the executive says.
The supplier has made a financial commitment in kenaf-based materials, having established two technical centers in Indonesia, in Melang and Balipapan, and several plantations in East Java.
In addition to expanding applications for plant-based materials, Toyota Boshoku, Japan’s leading car-seat manufacturer, has developed a new lightweight standard seat frame for B-, C- and D-segment cars.
Designated TB-NF110, the frame debuted on the new Prius in spring 2009. It is 3 lbs. (1.4 kg) lighter than previous frames due to expanded use of high-tensile steel.
The frame eventually will be adopted for more than 70% of vehicles in Toyota’s lineup – all but luxury sedans, fullsize pickups and super-compacts such as the midget IQ, Nakagawa says.
