Toho Tenax develops energy-saving, high-productivity carbonizing process and surface treatment technologies for CFRP
Toho Tenax Co., Ltd., the core company of the Teijin Group’s carbon fibers and composites business, has developed innovative microwave carbonization and plasma surface treatment technologies to support the increased production and use of carbon fiber reinforced plastic (CFRP) in automobiles, high-speed railcars and aircraft.
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 improving productivity.
Carbon fiber applications are expanding beyond aerospace into fields including automobiles, the environment, energy and infrastructure. However, the carbonizing process in the carbon fiber manufacturing process consumes large amounts of energy and produces CO2 emissions, so reductions in these areas are required to facilitate large-scale mass production for automobiles and other applications.
Microwave carbonization. Toho Tenax, using the world’s first 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 advanced carbonizing process was developed by examining the fiber- structure formation process when carbonizing a bundle of between 12,000 and 24,000 pieces of flame-resistant oxidized PAN fibers, 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 fiber ultra-fast plasma surface treatment technology using dry process. The highly simplified process reduces energy consumption by 50% for the whole process, compared to the conventional carbon fiber production process. In addition, the ultra-fast treatment improves the adhesiveness of carbon fiber and matrix resin.
Toho Tenax’s research and development programs 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 fiber mass-production processes for inventive CFRP applications. Toho Tenax has been participating in the project from the early stage.