What we missed in 2016: The other CNF (cellulose nanofibers, that is)

As journalists, we don’t like missing stories of significance, so I was somewhat aggrieved to have overlooked an emerging technology making waves in Japan of late. While researching the use of super adsorbent polymer (SAP) in hygiene products, I noted that all the leading Japanese paper producers were actively engaged in R&D of cellulose nanofibers (CNF; the same acronym that is used for carbon nanofibers).

Turns out that these less glamorous CNFs, measuring 3 to 4 nanometers in diameter, are excellent reinforcing fibers for composites, but have proved challenging to manufacture. That’s changing now with Nippon Paper Industries building the world's largest commercial-scale CNF facility in the quake-ravaged city of Ishinomaki, in northeastern Japan, with an annual production capacity of 500 tonnes. The unit is scheduled to commence operations in April 2017.

Nippon Paper Industries has been developing CNF manufacturing technologies since 2007, and installed a demonstration facility with an annual production capacity of 30 tonnes at the Iwakuni Mill (Yamaguchi Prefecture) in October 2013. Besides plastic nanocomposites, Nippon Paper has also developed and commercialized sheet products fabricated from CNFs functionalized with metal ions to deliver antimicrobial and deodorizing functions

For its part, fellow Japanese company Oji Paper started up a 40-tonnes/year pilot plant in the second half of 2016 to demonstrate an energy-efficient process for CNF manufacture. The technology will reportedly produce CNFs with high transparency, opening up further applications potential.

A third Japanese paper company, Daio Paper, has developed a CNF sheet material comprising up to 90% by weight of the nanofibers and compared it with the performance of an unidentified commodity plastic. A sheet with 80% CNF content and a thickness of 0.1 to 0.5 mm reportedly exhibits around five times the flexural modulus (13 to 17 GPa) at 23 deg C and around 20 times that (10 to 12 GPa) at 90 deg C. Tensile strength is around five-fold (100 to 150 MPa) at 23 deg C.

Sample shipments of the Daio Paper product are scheduled to start in March 2017. One target application that will exploit the barrier properties of the material is CNF food packaging.

Finally, Chuetsu Pulp & Paper has been working with Kyushu University and plans to start commercial production of CNF in 2017. Currently piloting production technology at a 30-odd-tonnes/year unit in Toyama Prefecture, the commercial plant will be 10 times larger. Chuetsu is targeting auto parts as a key application area.

CNF producers hope to lower the cost per kg to around the $10 mark by 202o through commercial-scale production. Analysts expect that the market for CNF will grow to 1 trillion yen ($8.7 billion) by 2030.

If all goes according to plan, CNF could become a competitor of commodity plastics such as polypropylene in durable applications as well as a complementary material for reinforcing and functionalizing. Watch this space.