Toho Tenax, the core company of the Teijin Group’s carbon fibres and composites business, has developed technologies for innovative microwave carbonization and plasma surface treatment, which are expected to help energy and CO2 emissions saving production of automobiles, high-speed railcars and aircrafts through increased use of carbon fibre reinforced plastic (CFRP).

Toho Tenax is now working to commercialize the technologies for mass production in the coming future, when CFRP is expected to be used on an increasingly large scale.

For CFRP solutions broadly incorporating everything from raw materials to composite materials, the company has been placing a special emphasis on reducing production-use energy and CO2 emissions by 50% while dramatically improving productivity.

Microwave carbonization

Toho Tenax, using the application of microwave energy carbonization under atmospheric pressure, has achieved a tensile modulus of 240 GPa or greater and rupture elongation of 1.5% or greater, both equivalent to levels found in industrial products, the company reports.

The advanced carbonizing process was developed by examining the fibre- structure formation process when carbonizing a bundle of between 12,000 and 24,000 pieces of flame-resistant oxidized PAN fibres, and then developing the most appropriate microwave processing method to carbonize this fibrous material. Using direct heating with microwave energy, fibrous material is carbonized continuously without having to maintain a high-temperature oven, thereby saving time and energy.

Surface treatment technology

Toho Tenax has also succeeded in developing a carbon fibre ultra-fast plasma surface treatment technology using dry process. The highly simplified process is said to reduce energy consumption by 50% for the whole process, compared to the conventional carbon fibre production process.

In addition, the ultra-fast treatment is designed to improve the adhesiveness of carbon fibre and matrix resin.

Carbon fibre applications

Carbon fibre applications are expanding beyond aerospace into fields including automobiles, the environment, energy and infrastructure. However, the carbonizing process in the carbon fibre manufacturing process consumes large amounts of energy and produces CO2 emissions, so reductions in these areas are urgently required to facilitate large-scale mass production for automobiles and other applications.

Toho Tenax’s research and development programmes were implemented by Japan’s New Energy and Industrial Technology Development Organization (NEDO). NEDO began promoting the research and development of innovative materials and technologies in 2014.

One of the core themes of this initiative has been the research and development of core technologies for innovative carbon fibre mass-production processes for inventive CFRP applications. Toho Tenax has been participating in the project from the early stage.

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