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Cellulose Nanofiber Research in Japan

Outline

© Japanest NIPPON

In the modern era, Japan has had a reputation as a country of limited natural resources. However, recent research efforts have found an innovative way of using one of the oldest resources and drawing attention; wood and its main product, paper. Japan is a country with a disproportionally large area of forest*, and if this vast resource could be harnessed effectively and sustainably, Japan may find itself in the position of being a resource-rich country.
*In fact, around 70% of land in Japan is covered by trees, and the ratio of forest-to-land is the second highest in the world after Finland.
How has paper, made of wood, captured scientists' imaginations? By revisiting this old material through new eyes, researchers have developed a novel type of paper that goes beyond our imagination.
Certain species of tree can grow to over a hundred meters tall and live for several thousand years, all the while maintaining a relatively unchanging outward appearance. The main structure of wood, or cytoskeleton, is made from the material cellulose, which is also the primary constituent of paper. The new form of paper is attracting global recognition is called “cellulose nanofiber”, which is manufactured by reconstructing cellulose after refining it at the nanoscopic level.
To make cellulose nanofibers, the natural cellulose is initially extracted from wood. Then, the structure is effectively strengthened on a molecular level by compressing the formation of cellulose; the space between the fibres is reduced and the number of links between them increases. The resulting product is far more durable than conventional paper — in fact, its strength is more than five times that of steel. In addition to its strength, cellulose nanofiber performs well in several other categories;
  • Lightweight and durable (compared to the same volume of steel, cellulose nanofiber is around 20 % of the weight but 7–8 times stronger).
  • Unlike steel or glass, it is flexible.
  • Small thermal deformation (1/50 of glass).
  • By producing cellulose nanofiber on a large scale in the future with technological advancements, manufacturing costs could be reduced to approximately 1/6 of those of carbon fibre.
  • As cellulose nanofiber is derived from plants, production, storage, delivery, and application have less environmental impact.
  • As cellulose nanofibers may be produced from a huge range of plants, the extremely large production capacity of cellulose nanofiber* dwarfs any other available resource.

* It is estimated that there are 1.8 trillion tons of cellulose vs. 150 billion tons (approx. 1 trillion barrels) of oil on the earth.


Dream material for wide variety of use


Cellulose nanofiber is expected to be used in a variety of products, such as raw materials for automobiles, mechanical parts, building materials, information technology components, pharmaceutical products, food, and cosmetics.
For example, a car produced using cellulose nanofiber would weigh far less than one made from today’s industry-standard materials and therefore greatly improve fuel consumption. Moreover, cellulose nanofiber does not reflect light due to much smaller structure size (5–15 nm) than visible light (350–830 nm), therefore making it possible to create transparent materials from wood. These materials could then be used to produce windows that are stronger than glass, new display parts, and food containers.
Currently, manufacturers in the pulp and paper industry and research institutions all over the world are vigorously researching cellulose nanofibers, and consequently the competition for product development has greatly intensified in recent years.  Amid this climate of intense competition, research institutions in Japan have pushed far ahead in terms of application development, and lead the world in their comprehensive investigation into the entire cellulose nanofiber manufacturing process, from the isolation of raw materials, to creation of composite materials, to final production.
Furthermore, companies in both the pulp and paper industry and the chemical industry have already announced strategies for the production and application of cellulose nanofiber.

So, here are some examples.

Mitsubishi Pencil produced the world’s first product containing cellulose nanofiber, a ballpoint pen that has received high acclaim for its smooth, free-flowing writing. By using cellulose nanofiber as a thickening agent in its ink, the pen avoids common writing issues of skipping and clumping. Since first becoming available across North America in March 2015, it has since gone on sale in other Western countries in September 2015.
In October 2015, Nippon Paper Crecia (a part of Nippon Paper Group) demonstrated that cellulose nanofiber can be readily combined with other new technologies to create innovative products: they developed paper diapers with a high performance antibacterial and deodorising sheet. This sheet is constructed from cellulose nanofibers, and the fibers act as an anchor for metal nanoparticles and metal ions that give the sheet its antibacterial and deodorant properties. In 2016, they plan to operate assembly lines that are expected to increase production capacity by more than ten times. These cellulose nanofiber sheets are manufactured using two processes: the first process, referred to as ‘TEMPO-mediated oxidation of cellulose nanofiber’, is used to create the sheets, and was developed by Dr. Isogai and colleagues at The University of Tokyo — he has since received the Marcus Wallenberg Prize for his role in developing this process. The second process generates metal nanoparticles on the surface of the nanofiber sheets, and was developed by Dr. Kitaoka and colleagues at Kyushu University.
Oji Holdings and Mitsubishi Chemical have been engaged in a collaborative research partnership since 2009, and have made a number of notable achievements. First, in 2013 they succeeded in producing a transparent, continuous sheet of cellulose nanofiber, a breakthrough that has significant implications for the future of flexible electronics: this technology is expected to be used in lightweight, rollable, and foldable display panels and solar batteries. Both companies plan to move forward with commercial production from 2016 onward.  Large-scale production of transparent cellulose nanofiber will enable the development and production of flexible electronic devices: these devices are highly portable, allowing them to be moved around and set up with ease, thereby offering far more possibilities for their use than conventional displays. Oji Holdings also entered into a joint partnership agreement with Nikko Chemicals to develop cosmetic materials in 2015, a project that is already bearing fruit as cellulose nanofiber cosmetic products are now drawing substantial attention from cosmetic and related companies.

Now, R&D of cellulose nanofiber–based technologies is no longer limited to certain companies and universities, but is becoming a national goal. In 2014, Japanese government announced promotion of cellulose nanofiber R&D as a national policy. Cellulose nanofiber R&D was selected as one of the concrete policies detailed in the government-issued “Japan Revitalisation Strategies”. As development of cellulose nanofiber advances and more products become available, Japan stands to become a major producer of this material due to its vast wood resources, which will undoubtedly stimulate local economies in several areas across the country. We expect Japan to continue its diligent and comprehensive research program, and to remain as the world’s leader in cellulose nanofiber technology and products.


27 May, 2016

About the author
Hiromi Jitsukata is a reporter for Japanest NIPPON
Main Japanese Cellulose Nanofiber Re-search Centers
Isogai Group, The University of Tokyo (Received the Marcus Wallenberg Prize in 2015)
Yano Group, Kyoto University (Researching
since 1988, Japan’s pioneering research group)
Kondo Group, Kyushu University (Biomaterial
Design)
Okayama Green Bio Project
Kyoto Industry and Technology Group
National Institute of Advanced Industrial Science and Technology Nanocellulose Forum