A prototyped ultra-small EV
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Plastics for the body (left: CFRTP, right: GFRTP)
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Rimono, a Tokyo-based company that develops ultra-small electric vehicles (EVs), will employ plastics for the body of its vehicle to be released in the summer of 2017 to reduce the vehicle weight by 35% or more.

When Rimono announced a prototype of the vehicle May 20, 2016, it measured 2,200 (L) x 1,000 (W) x 1,300mm (H) and weighed 320kg. Its body components including the frame, front hood, front fender and doors were made of steel plate. On the other hand, for the vehicle to be released in 2017, the company aims to replace all of those components with plastic parts and realize a vehicle weight of 200kg or less.

"We will increase drive range as much as possible by reducing the vehicle weight," Rimono President Shinsuke Ito said.

Specifically, Rimono will use Mitsui Chemicals Inc's GFRTP (glass fiber reinforced thermoplastic) and CFRTP (carbon fiber reinforced thermoplastic). Their matrix resin is a modified polyamide (PA) having a higher heat resistance and a higher strength than normal PAs. They have already been employed for components located near the engine such as a water jacket as well as electrical components including the connector of the wire harness.

The tensile strengths of the GFRTP (content percentage of glass fibers: 50% by mass) and the CFRTP (content percentage of carbon fibers: 30% by mass) are 300MPa and 260MPa, respectively. Their specific strength is about three times higher than that of steel materials and about 1.5 times higher than that of aluminum alloys.

"They can be formed into body components by using a normal press-forming machine," Mitsui Chemicals said.

The surfaces of the latest prototype's body components are covered with Mitsui Chemicals' foamed polyurethane, and Teijin Frontier Co Ltd's polyester fabric is applied on top of that. Those exterior materials will also be used for the body of the vehicle to be released in 2017.