Chuetsu Pulp & Paper Co., working with Kyushu University, established a technique using bamboo to create cellulose nanofiber (CNF), which is five times stronger than steel but only one-fifth the weight of the metal.
The big hurdle is the production cost.
The company is expected to begin commercial production of CNF in June at its Sendai plant in Satsuma-Sendai, Kagoshima Prefecture. It plans to produce 100 tons of CNF a year.
CNF consists of the tiny reticulated structures of fibres from cellulose, which constitutes the cell walls of plants. It is created by breaking down wood pulp into extremely tiny pieces.
The thickness of CNF is about 10 nanometres, or one-ten-thousandth as thin as a hair. (One nanometre is one-billionth of a meter.)
When mixed with plastics or rubber, CNF improves the strength of the materials and prevents drastic changes in their shape caused by temperature fluctuations.
CNF can be made from all sorts of plants, but bamboo-derived CNF combines more easily with plastics and other types of resin than the material created with other kinds of trees.
Production of CNF could also help to solve an environmental problem.
Municipalities around Japan are trying to get rid of long-unattended bamboo thickets that can have a catastrophic impact on surrounding forests of other trees.
In Kyoto Prefecture, Japanese cypress and cedar trees have withered from damage caused by abandoned bamboo thickets.
New sprouts can spring up from quickly spreading bamboo roots. The shoots also grow rapidly to as high as about 20 meters, blocking sunshine and killing other plants around them. As a result, the soil becomes loose. This may have contributed to a landslide that occurred near a bamboo grove when a typhoon struck Kagawa Prefecture.
Kagoshima is the Japanese prefecture with the largest area of bamboo groves. The city of Satsuma-Sendai in the western part of the prefecture faces a growing problem with abandoned bamboo thickets because their owners are becoming too old to look after the plants.
At the request of local authorities and others, Chuetsu Pulp & Paper has bought an annual 20,000 tons of bamboo in the city since 1998.
The company produced paper from the bamboo, but it also started researching bamboo-made CNF to use the resource more effectively.
According to the Forestry Agency, Japan had 161,000 hectares of bamboo groves as of 2012, up 12 percent from 1981.
Bamboo has been used for charcoal, paper, road paving material and other products, but demand for the wood has been shrinking.
“To prevent further expansion of bamboo thickets, there is no choice but to put the commercial use (of bamboo) on the track to success,” said Shigeo Suzuki, a lecturer of ecological geography at Rissho University.
CNF made from plants other than bamboo have been used in products already on the market.
Nippon Paper Industries Co. in October 2015 started selling a disposable diaper for adults that has a CNF-made sheet in a part that does not come into contact with the user’s skin. This improves the product’s deodorizing effect.
Starting in spring, Nippon Paper Industries will increase its annual CNF production at plants in Ishinomaki, Miyagi Prefecture, and elsewhere to more than 500 tons.
Although CNF’s main ingredient, pulp, is available for around 50 yen (US$ 44 cents) per kilogram, the process of breaking the fibre into small pieces requires labour and money. Manufacturing expenses run to several thousand yen (dozens of dollars) per kilogram.
Kyoto University is proceeding with research projects to cut CNF production costs and reduce the weight of automobiles by replacing parts with ones made of CNF.
Full-fledged research on CNF began around 2004. The United States, China and countries in northern Europe have aggressively been involved in developing the strong fibre.
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