Before reflecting on the issues, let’s consider the features first, while reflecting on the fact that it is a shallow knowledge.
①Lightweight and 5 times stronger than iron
② Less deformation due to heat
③ Low environmental load due to plant origin
④ Abundant resources
Is this around here? Some products have actually been commercialized, and it appears that the joint research between Chuetsu Pulp and Paper Industry and Idemitsu Lion Composite has begun production of high-strength resin into which cellulose nanofibers are kneaded.
Isn’t cost a challenge?
Since it is not yet in mass production, it is expected that the price will be over 3,000 yen to 5,000 yen / kg in gel form.
Also, it is difficult to knead with resin because it is a gel, and its concentration is about 2 to 10%, so it seems that it is difficult to get on the experimental table for development.
It seems that powder type cellulose nanofiber has been developed to increase the concentration of CNF, but the price is tens of thousands of yen / kg.
Raw materials are abundant materials, so the price will drop sharply when entering mass production. Because it is an important technology in Japan, we want to somehow commercialize it before other countries and distribute it to the general public.
Another issue is that it is flammable because it is cellulose. Although it is known that mixing a certain amount in plastics increases the strength, development seems to be suspended sometimes because flame retardancy cannot be provided.
We believe that a flame retardant that is highly effective for cellulosic materials is compatible.
Boric acid is known to have a high flame retardant effect on cellulose. Boric acid has long been recognized as having an effect on cellulose. However, in the flame retardant industry, there are almost no flame retardants that use boric acid as the main raw material, and the current situation is that they rely on halogens, phosphorus compounds, antimony, and the like.
We think that the compatibility with our sodium polyborate is good.
Isn’t dispersibility good if you settle well on cnf? I believe.
We have conducted tests to give the flame retardancy of cellulose nanofiber.
Samples were provided by several cellulose nanofiber manufacturers.
Aqueous flame retardant is made by mixing cellulose nanofiber and soufa. It was applied to a PP plate and subjected to a 45 ° C combustion test. There was no fire penetration.
The process of imparting hydrophilicity to PP by plasma treatment was necessary, but we will continue to study various materials in the future. The flame retardant mechanism is oxygen blocking by the firing of sodium polyborate and carbonization promotion by cellulose nanofiber functioning as a carbonizing agent. Originally, it was known that sodium polyborate can promote carbonization when used in combination with starch, so we thought that it could be applied to cellulose nanofibers with a similar structure.
Although the effect was almost the same as starch, it seems that there are some materials where cellulose nanofibers are more effective.
The application with cellulose nanofibers will be addressed in the future.
Since boric acid is also effective for wood preservation and insect repellency, isn’t it quite compatible with CNF?
No literature on the flame retardancy studies of cellulose nanofibers has yet been seen, so it can be seen as an indication of where to start. I hope that if flame retardancy can be achieved, it may be used as a material for automobiles and jet aircraft that require flame retardancy.