Eco-friendly high-
performance cellulose
materials
In recent years, eco-friendly sustainable
materials have been getting attention.
I am seeking to develop high-performance
cellulose materials and put them into
practical use,
based on the idea of
“transparent paper.”
Seiji Kasahara
Index
Retry in a field of expertise
after the first-year failed
attempt
Since joining the company in 2019, I have been working on the research and development of inorganic semiconductors through the use of material analysis and simulation techniques. I majored in chemistry in college, and my field of expertise has since been conductive diamond. After graduation, I chose to join Sony because I liked its environment where younger employees are given plenty of discretion. So, after entering the company, I was determined to take every opportunity to present my work and ideas freely. I learned of an internal bottom-up research support event called Challe-Suppo when the company decided to award the Grand Prize winners a right to pursue their themes in projects, as well as to provide funding for development. I thought to myself that the long-awaited chance was coming.
It was in my second year after joining the company that I won the Challe-Suppo Grand Prize. Though, I participated in this competition in my first year, too, with a theme of e-books which was not my specialty. It got positive feedback from people inside the company, but I did not win any prize. I think that my presentation was unconvincing because it was not related to the field of expertise that I had being working on, such as conductive diamond and inorganic semiconductors.
I was looking for a new theme for the 2020 competition to try again with something closer to my field of expertise when I came across a news report about a major coffee chain switching from plastic straws to paper ones in all its outlets in Japan. While I had been aware of worldwide discussions about contribution to SDGs and responsibility for the global environment, this news brought home to me that several companies were also taking concrete actions in Japan.
On the other hand, I suspect that the idea of switching from plastic to paper was not widely accepted yet. One of the reasons that came to my mind was that the transparency is realized in plastic but not in paper. In a coffee shop, for example, it may be important that the cups are transparent so that one can see what is inside at a glance, or that iced drinks feel cool. This made me think that new “transparent paper” materials could accelerate the switch from plastic to paper.
Biggest lesson learned:
From upstream to downstream
Soon after starting to gather information for my presentation, I learned that cellulose nanofiber (CNF) was already in practical use as “transparent paper.” CNF itself has been studied since about 20 years ago, and it is widely known in the materials research community that this material has excellent properties of being transparent, lightweight, and durable.
But it is still rare to see CNF in everyday life. While there are some possible reasons for this, I thought that one of the reasons is that it is more expensive than existing chemical materials such as carbon fiber and polyethylene. The cost of new materials is high, but I think that the strong appeal points that outweigh these costs have not yet been realized, and this is the reason why they have not been widely used in our daily life.
While studying about CNF, I found that the key in material development is to make the material attractive to businesses and consumers with a broad perspective ranging from the features and performance of the material to its usage. It might be important to keep considering how technologies can contribute realizing customer values in corporate R&D. Sony has B2C products and deals with the whole process from manufacturing to marketing, so that we can be involved in research activity considering issues in production or users’ views. This is really privileged environment.
Challenges for future material
research and development
Since winning the Grand Prize, I have expanded the scope of my research from “transparent paper,” exploring ways to fit cellulose materials into Sony’s supply chain. In changing the existing supply chain, it is important to analyze the needs of product developers and users carefully. Particularly, this theme is new, so I am doing my R&D work while actively communicating with people both inside and outside the company.
The Sony Group has put some new materials into commercial use in the past several years. One of them is Original Blended Material, which is used in the packaging of the fully wireless earphones WF-1000XM4. It is made from post-consumer recycled paper and bamboo and sugarcane fibers. Another example is a unique felt material used in the packaging of aibo robots. Recycled materials derived from used plastic bottles account for 50% of the components of this new felt material.
I build my knowledge about the development of new materials by talking with the engineers in charge of these products and participating in the Technology Strategy Committee activities where Sony Group engineers gather to discuss topics on a specific technology. Listening to engineers who handle materials in their work and employees involved in product development helps me identify problems that cannot be perceived through my daily material analysis work. So, I consider it important to interact with these people.
I hope to contribute to realizing a sustainable society by continuing my R&D work on materials at Sony. There is still a long way to go before the materials that I develop are used in Sony products. I will keep working hard with the support of my team members and colleagues.
COLUMN
Nanofiber material made from
plant-derived cellulose
Paper is made by removing unnecessary ingredients from plant material and forming extracted cellulose fibers into shape. While cellulose fibers are transparent by nature, paper looks white. This is the same in principle as the phenomenon that water is transparent whereas snow looks white. An object looks transparent when the light in the visible range passes through its surface and bulk. Paper looks white because light is scattered by the roughness on its surface and the voids in its bulk. When a few drops of water are put on a sheet of white tissue paper, that moistened part of the paper looks transparent. This is considered to be because the water fills the voids inside, reduce the scattering of light.
Cellulose nanofiber (CNF) is made by treating cellulose fibers chemically and mechanically to break them down into extremely fine specks (in diameters less than few hundreds of nanometers). The size of CNF is said to be one- to ten-thousandth the size of the typical paper fiber. If the fiber size becomes smaller than a certain level, no voids develop when fibers are formed into sheets. This makes CNF transparent as the cellulose originally is. CNF is a plant-derived eco-friendly transparent material. Moreover, it is five times lighter and mechanically stronger than steel and has high elasticity, excellent moisture-retaining and gas barrier properties, high hydrophilic performance, and a low thermal expansion coefficient among other features. So, it is expected that CNF will be used in a wide variety of applications, including automotive and aircraft parts, construction materials, electronic devices, coating materials, and cosmetic additives.
