Once the most promising of all nanomaterials, carbon nanotubes are in danger of being usurped in numerous applications by the likes of graphene. We investigate the current market and future prospects.
There are already a number of carbon nanotubes (CNT) applications on the market. Applications include strength and stiffness reinforcement composite additives in sporting goods and thermoplastics, EMI/RFI (electromagnetic and radio frequency interference) shielding composites, electrostatic dissipation (ESD), antistatic materials, conductive battery electrode additives and coatings. Examples in the automotive industry are fuel systems components and fuel lines (connectors, pump parts, o-rings etc.) and exterior body parts for electrostatic painting. New structural composite materials based on CNT reinforced thermoplastics or thermosets combine low density and strong mechanical properties and will open the way to new developments in particular by replacing metals in various mechanical applications where a weight reduction could save energy.
Medium-term applications
In terms of medium to long-term applications, several current applications will be expanded to other industries. For example, the improvement of mechanical properties in epoxy-glass fiber or epoxy–carbon fiber composites already known from the sport industry can also be used in the construction of light weighted composites for wind power generators and in the aircraft industry. Due to the nature of these industries, more technical testing and longer certification time will be required. Other medium term applications may include electrical conductive inks for printable circuits, low cost RFID tags or antennas in cars. In the longer term, CNTs may also play a role in the modification of existing textile materials using electrostatic self-assembly and atomic layer deposition techniques to create novel and customizable surfaces on conventional textile materials with emphasis on natural fibers. This opens the way to the development of smart and intelligent textiles that combine new innovative functions.
Coatings
Properties of carbon nanotubes of interest for coatings applications include their electrical conductivity, thermal conductivity, and mechanical properties. There is at least one commercial marine coating on the market that incorporates nanotubes to provide enhanced abrasion resistance. Formulations with nanotubes are also being investigated as anti-fouling coatings for marine applications and as additives for anti-static coatings where static discharge may otherwise be considered dangerous. It has also been demonstrated that combining nanotubes with graphene in coatings could lead to a greatly enhanced material, for example in aerogels.
The electronics market is likely to be the largest medium-term market for carbon nanotubes, especially single-walled carbon nanotubes (SWNT), for ITO replacement, as flexible displays become more widespread. Carbon nanotubes are utilized as transparent conductive thin films. Applications in batteries and supercapacitors will also continue to grow.
Production
Production volumes for nanotubes have been scaled up considerably over the last few years. Companies such as Showa Denko and Bayer are producing hundreds of tons of nanotubes per year. Prices of MWNTs now range from $45-70/kg, depending on quality, with, Chinese manufacturers offering MWNTs at lower prices. Nanotube additives in lithium-ion battery electrodes were one of the first nanotube applications marketed by Showa Denko, which has a capacity of 500 tons/year.
Product development thus far has generally been as a result of collaboration between large multi-national companies and small application developers and innovative producers. Collaborations include ApNano Materials, Inc. (nanotube lubricants), Applied Nanotech, Inc. and Arima Eco Energy Technologies Corporation (photovoltaics), Nanomix and Dupont (field emission displays) and Nanoledge and a number of companies including Structil, Seal, SK Chemicals, Look Cycle, Babolat, Cobra, Suzlon Huntsman and Bayer in the sporting goods sector.
The current capacity for the production of MWCNTs far exceeds that of SWCNTs. SWCNTs are much more expensive and difficult to manufacture than MWCNTs, and there is not yet a distinct large-scale market for SWCNTs, which is needed to drive down the production cost. However, production of SWNTs is expected to reach multi-ton levels by 2017. Current production volume of SWNTs is approximately 1 ton per annum.
MWCNTs Production capacities (tons per year unless otherwise stated)
• Arkema: 400
• Bayer: 250
• Cheaptubes: 20
• CNano: 500
• Carbon Nanotech Res. Inst. Inc: 5
• Catalytic Materials: 1.2kg/day
• Eden Energy/Hythane Company LLC: 3
• Hyperion Catalysis: 50
• Hanwha Nanotech Corporation: 120
• Mitsui/Hodogaya Chemical : 140
• Nanoamor: 30-50kg.day
• Nanocarblab: 3g/day
• Nanocyl: 400
• NanoLab: 200-100g/day
• Nanoledge: 100
• Nanostructured & Amorphous Materials: 4
• Nanothinx: 100/day
• Raymor Industries: 10
• Rosseter: 100-200g/day
• Shenzhen Nanotech Port: 200
• Showa Denko: 500
• SouthWest NanoTechnologies, Inc.: 10
• Sun Nanotech Co., Ltd.: 100
• Thomas Swan: 12
• Toray: 250
SWCNTs production capacities (tons per year unless otherwise stated)
• Carbolex: 250g/wk
• Unidym: 1.5
• Toray: 1.5
• Mitsubishi Rayon Co. Ltd.: 1.2
• SouthWest Nanotechnologies, Inc: 1
• Kleancarbon, Inc. : 1
Main markets companies supply nanotubes to are:
• Academia and university laboratories
• Plastics and electronics manufacturers
• Materials and Battery companies, Catalyst and Automobile manufacturers
• Sensors
• Field emissions
• Polymer composites and additives.
• Aerospace.
For both types of CNTs, Asia’s production capacity is two to three times higher than that estimated for North America and Europe combined; Japan is the prominent leader in the production of MWCNTs. Use of CNTs in lithium-ion battery electrodes is the current driving force of ton-scale MWCNT production in Japan. CNT-replacement products for indium tin oxide (ITO) and field emission devices (FEDs) are driving increased production of SWCNTs, whereas applications using transistors require precise control over CNT diameter and conductivity, which is farther from commercial realization. When the cost of bulk SWCNTs decreases significantly, applications in electromagnetic shielding (EMI) and electrostatic discharge (ESD) protection can be expected, and SWCNTs will replace MWCNTs in conductive plastics.
