Plastics slim down Japanese electric car

Comments Email Print

Plastics are playing a role in helping a next-generation Japanese electric car slim down and extend its driving range 30 percent beyond current mass-produced electric vehicles.

The SIM-WIL prototype car, made by Japanese technology development firm SIM Drive Corp., uses plastics in key components like the in-wheel motor and as a film replacement for circuit boards.

DuPont, which supplied several materials to Kawasaki-based SIM Drive, said in a July 19 announcement that the use of lightweight materials and a unique “in-wheel” motor system were responsible for the significant increase in the car’s driving range.

“This project shows how light weight, high-performance materials such as Zytel HTN [nylon] can take extremes, allowing designers to bring innovation to electric and hybrid vehicles without adding weight associated with metal,” said James Hay, regional director of DuPont Performance Polymers, Asia Pacific.

Officials from SIM did not respond to a request for comment, but the company said when it announced the car in March that its goal is to build electric cars with the same performance and comfort as traditional gas-powered vehicles.

The SIM-WIL, for example, has acceleration similar to a mid-range sports car and an interior cabin the size of a luxury sedan but the body size of a subcompact, the Japanese firm said.

When it announced the vehicle, SIM Drive did not specifically mention any special role for plastics, but it did tout the use of new metals, including a monocoque steel space frame used for the first time.

That frame allows for important advances in lightweighting, low production costs and high rigidity, SIM Drive said.

The company said it hopes to start mass production in 2014, and said one of the goals of the prototype has been to demonstrate that the technologies from its 34 different partners are reliable enough for mass production.

DuPont said the project uses eight different DuPont plastics, film, paper and coatings, including Zytel for the in-wheel motor bobbins, which are stronger, lighter and more cost-effective than the polyphenylene sulfide parts they replace.

DuPont also said the vehicle uses Kapton polyimide film in the indicator lighting, eliminating the need for a circuit board and reducing the weight of the lighting component by 80 percent.

The prototype work had a lot of value for DuPont, a company official said.

DuPont was able to be closely involved in the early stage design work for the car, an area that is normally difficult for materials firms to participate in, said Suzue Kikuyama, a DuPont manager in the company’s hybrid-electric vehicle unit in Tokyo.

She also said DuPont was interested in the project because to date, no one has mass-produced an electric car using an in-wheel motor system. It’s the first time the company’s Zytel material has been used in an in-wheel motor bobbin, she said.

Development work for those parts was done at DuPont’s innovation center in Nagoya, Japan.

SIM Drive said the car can travel 218 miles on a single charge and accelerate from 0 to 60 miles per hour in 5.4 seconds.

Beyond DuPont, SIM said it worked with several other materials firms, including Toray Industries Inc., which supplied carbon-fiber reinforced plastic prepregs.

Other partners include Japanese engineering plastics compounder Polyplastics Co. Ltd. and Kuraray Co. Ltd., SIM Drive said.