A new chapter in carbon fiber recycling: How to realize 100% carbon fiber recycling technology?

The so-called recycling or reuse of carbon fiber composite waste is mainly for carbon fiber reinforced plastic (CFRP), because according to surveys it has accounted for more than 90% of the carbon fiber market. With the application of CFRP in aerospace, large wind power blades, and civil construction With the rapid expansion of applications in automobiles, automobiles and other fields, the development and industrialization of its waste recycling technology is urgent. Among them, carbon fiber reinforced thermoplastic resin (CFRTP) can be made into chips and reused, while the recycling of carbon fiber reinforced thermosetting resin is difficult.

Recently, Georgia Institute of Technology researchers have developed a new CFRP carbon fiber recycling process that can achieve almost 100% recycling of certain types of CFRP.

How to achieve 100% recycled carbon fiber?

This new method is to separate the carbon fiber from the epoxy resin by soaking the composite material in an ethanol solvent to slowly dissolve the epoxy resin, enabling new applications.

According to Jerry Qi, a professor at the Georgia Institute of Technology, the recycling of traditional carbon fibers faces challenges – the polymer matrix of CFRP is usually a cross-linked structure like rubber and cannot be easily dissolved, so it is difficult to remove the polymer to recycle the polymer embedded in it. of more valuable carbon fiber. A special epoxy resin called vitrimer studied by the research team contains dynamic bonds that can replace the structure under certain conditions without damaging the integrity of the cross-linked network, by allowing the small molecule compound ethanol to participate in the network structure. Effectively dissolves vitrimers in substitution reactions. This new recycling process has the potential to recycle thousands of tons of carbon fiber waste generated each year in the United States and Europe. At the same time, this method also has another significant advantage, that is, the process is simple and fast.

What other industrialized carbon fiber recycling processes are there?

(1) Toray, Toho Tenax and Mitsubishi Rayon Corporation

As early as 2006, the Ministry of International Trade and Industry of Japan built a pilot plant in Omuta City, Fukuoka Prefecture through its subsidy of the “Empirical Research and Development of Carbon Fiber Recycling Technology” project. Since 2009, it has received funding from Fukuoka Prefecture and Omuta City, thus It can be used as an activity content of the Japan Carbon Fiber Manufacturers Association (JCMA) and is actively engaged in basic technology development. Through research, a recycled carbon fiber technology that can control the length of recycled carbon fibers and remove metal impurities and low resin residues has been achieved, thereby achieving the development goals of the Carbon Fiber Association, and the association activities were terminated at the end of 2013. To this end, the above-mentioned three PAN-CF companies have established a “Carbon Fiber Recycling Technology Development Portfolio” to further deepen the recycling technology and achieve industrialization.

According to a report released by Japan’s Hitachi Chemical Company in 2014, the JCMA recycling plant, in conjunction with Toray Corporation, Japan’s Teijin Group, and Japan’s Mitsubishi Rayon Corporation, has expanded the production of RCF that does not require pre-crushing for the pyrolysis process. technology. Prior to this, JCMA already had an RCF production capacity of 1,000t/a. This new new process has a recycling capacity of 60t/a, and can even recycle continuous products.�Fibers and discontinuously arranged RCFs (e.g. oriented versus random).

(2) Japan Carbon Fiber Recycling Industrial Co., Ltd.

The unique technology of pyrolysis method to recover carbon fiber from waste CFRP created by Japan Carbon Fiber Recycling Industries (CFRI) is characterized by using the thermal decomposition gas generated when the waste is burned as the heat source of the carbon fiber recycling project, thus saving 6% compared with previous methods. The energy is generated, and the strength of the recycled carbon fiber can reach more than 80% of the original carbon fiber; the regeneration process is obtained through two-stage sintering in the carbonization furnace and the sintering furnace, and the long fibers can be recycled intact. The carbon fiber recycled by this recycling system has a production capacity of approximately 60 t/a. Currently, this recycled product has been used in automotive parts, which can reduce the weight of the entire vehicle by more than 20%.

(3) German BMW and American Boeing Company

In 2012, German BMW (BMW) and the American Boeing Aircraft Company reached an agreement to jointly develop carbon fiber recycling technology, including the sharing of manufacturing technology secrets, and are committed to the research of automated processes. Boeing’s B-787 aircraft, which uses about 50% CFRP, has been put into commercial operation and is currently producing 7 aircraft per month. BMW has also begun to use discarded recycled materials in its i3 and i8 series models. SGL Automotive Carbon Fiber, which produces carbon fiber auto parts for BMW, has obtained RCF by collecting i-series auto CFRP woven and knitted preform waste, and recycled RCF is made into quilted nonwoven materials that are used to produce CFRP for the roof and rear seats of the i3 and i8.

(4) Germany’s CFK Valley e.V. and Karl Meyer AG

Germany’s CFK Valley e.V. cooperated with Karl Meyer AG to establish an industrialized RCF production line called CFK Valley Recycling in 2007. It currently has a production capacity of 1,000t/a recycled carbon fiber. In 2011, German metal recycling producer ELG Haniel also entered the RCF market by acquiring British Recycled Carbon Fiber and its commercial recycling plant.

CFK Valley Recycling’s industrialized RCF production line (1 sorting; 2 pyrolysis; 3 surface treatment; 4 cutting; 5 distribution)

In addition, Japan’s Hitachi Chemical, Japan Fine Ceramics Center (JFCC) and Datong University, Germany’s RWTH Aachen University Textile Technology Research Institute, Siemens Central Research Institute, Germany’s Saxony Textile Research Institute (STFI), etc. have all developed carbon fiber recycling that can be industrialized Technology, it is clear that the current recycling and reuse of CFRP can solve technical problems. The main problems faced are industrialization and market application.