Solution 04

Carbon Fiber & Composites

Aiming to create an eco-friendly future with “light weight and strong materials”

Feb. 1, 2023 / TEXT BY YUYA OYAMADA 

※ Article updated on Mar 2, 2022

The field of mobility is ushering in a major transition to its business model to realize carbon neutrality. A certain material is gaining focus given that automobile manufacturers are undertaking the spread of electric vehicles (EVs). It is carbon fiber reinforced plastics (CFRP), which contributes to reducing the weight of vehicle bodies.

Carbon Fiber & Composites image

The utmost feature of carbon fiber is that it is light weight, and has high strength and modulus. Although its specific gravity is one-fourth that of steel, carbon fiber boasts excellent strength and elasticity.

Mitsubishi Chemical Corporation (MCC), a member of the Mitsubishi Chemical Group, is the only company in the world that manufactures two types of carbon fiber. The company produces PAN-based carbon fiber, which uses acrylonitrile as a raw material, and Pitch-based carbon fiber, which is produced using coal tar as a raw material. Pitch coke is derived from coal refining.

A strength of MCC is that it proprietarily conducts the manufacturing and sales of carbon fibers, spanning from raw materials to the carbon fiber itself, intermediate materials and CFRPs. The company has cultivated diverse knowhow and proposal capabilities related to carbon fibers, including material design and molding/processing technologies. The company also handles two types of carbon fibers, PAN and Pitch based. The company supplies CFRP that fulfills diverse applications and needs, including in the fields of automobiles, aerospace, and sports and leisure equipment, such as golf shafts.

Metallic parts, including those made from steel and aluminum, are frequently used in conventional automobiles. However, with reflecting stricter fuel and CO2 emissions regulations, a major issue in the automotive industry has been to create lighter auto bodies.

In addition, given the acceleration in the shift from gasoline-powered cars to electric vehicles to realize carbon neutrality, it is essential to make auto bodies lighter than that of gasoline-powered cars to extend the driving distance of electric vehicles equipped with heavy batteries.

A key to solving this issue is CFRP. By replacing conventional materials with CFRP, it is possible to maintain the strength of auto bodies while making them lighter. In a past model study, it was reported that using CFRP in 17% of an auto body made it 30% lighter in weight (comparison with conventional materials), and that by making an auto body lighter in weight, the CO2 reduction benefit per vehicle over a 10-year period was around 5t.

It is expected that CFRP will substantially contribute to producing lighter weight auto bodies. Another issue is the spread of its use in the field of mobility. In contrast with conventional materials, it takes longer to produce parts and the production cost is high. The mainstream use of CFRP is in luxury cars, including sports vehicles.

MCC has therefore undertaken the development of CFRP that can be used in medium to mass production by leveraging the product design knowhow it has cultivated. One product it developed was carbon fiber FMC (CF-SMC: Carbon Fiber Sheet Molding Compound).

CF-SMC is an intermediate material that comes in sheet form, where cut carbon fiber is impregnated with thermoset resin. A feature of CF-SMC is that it can be mass produced using press molding. In comparison with traditional molding methods that use autoclaves and ovens, it is now possible to process automobile parts and components in a short time. Previously with autoclave molding, it took 2 hours to manufacture parts, but this has been curtailed to around a few minutes.

Autoclave Molding
Press Molding

Owing to this it is now possible to mass produce parts on a high cycle. The high performance of the material is maintained even at reduced cost, and a weight reduction of about 30% has been achieved when compared to aluminum at the same level of bending rigidity (material's resistance to bending). There is also underlying potential for saving manufacturing cost to a level equivalent to that of aluminum sometime in the future.

In addition, CF-SMC utilizes short carbon fibers, which allows for a high level of flexibility in design and the ability to be molded into complex shapes.

CF-SMC has already been adopted in the mobility field. Nissan Motor Co., Ltd. uses it in the diffuser for its GTR, Toyota Motor Corporation uses it in the doors and luggage interior in the Lexus LC500, in the backdoor interior of the Prius PHV, and recently, also in the roof its GR Yaris.

Moving forward, it is expected that the demand for lighter weight automobiles will increase further. As a result, the demand for CFRP is also expected to increase. Meanwhile, in the field of next-generation mobility, such as automated (autonomous) driving cars and “flying” cars, we anticipate new-concept auto body designs that diverge from conventional ideas.

In order to contribute to the realization of new forms of mobility, it is even more important to catch up with customers' needs as soon as possible. In light of this, MCC is strengthening its supply chain to transform its business operations from those that cover materials development in upstream-to-mid stream processes to operations that penetrate downstream processes which are close to the end-user automakers.

In 2017, MCC made an investment in C.P.C. SRL, an Italian company that handles automobile parts made from CFRP. The company is building a system to supply optimal solutions in a timely manner in the field of mobility, where there have been significant innovations, by using the knowhow and molding technology capabilities to create lighter weight parts and bodies that employ the design and simulation technologies of C.P.C., its development proposal capability and its network with US and European automobile manufacturers.

Also, by establishing new CF-SMC manufacturing facilities at C.P.C., the Group will respond to the growing demand for CFRP products. Even in the area of intermediate materials, MCC is strengthening its CFRP production facilities globally. In 2020, the company acquired c-m-p GmbH, a carbon fiber prepreg manufacturer in Germany.

In addition, in order to remain competitive, it is essential to build a supply chain that takes sustainability into account. That is why MCC is focusing on the carbon fiber recycling business at group companies, including Shinryo Corporation in Japan and carboNXT GmbH in Germany.

Build Recycling Business Model

At present, the company is at the stage where it separates carbon fiber from recovered CFRP and reuses it as a raw material. Further out, the company aims to establish a technology that would allow it to use as intermediates, recouped parts that possess performance equivalent to that of virgin materials. MCC aims to contribute to the realization of a circular economy as the only company with a consistent business model that spans from carbon fiber raw materials to recycling.

Carbon fiber is light and has high strength and modulus, which allow to make composite parts lighter. It is the material that possesses substantial potential in the field of mobility. When the age of electric vehicles finally dawns and electric cars become mainstream, if CFRPs that are lighter in weight and stronger than conventional ones are developed, eco-friendly electric vehicles that fly may no longer be a dream.


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