エコフレンドリーな素材の提案
Transparent paper that could help protect our oceans. It's based on a joint announcement by
JAMSTIC, the Japan Agency for Marine Arts, Science and Technology, along with the University of Tokyo
and Tokyo University of Science. Hi there and welcome to SCIEN-SPOT, the podcast that puts
the spotlight on the latest in science and technology in Japan. I'm REN, your host from
SCIEN-TALK. As many of you probably know, plastic waste in the ocean has become a major global
issue. JAMSTIC's previous research revealed that tons of plastic are accumulating on the deep sea
floor. And what's shocking is that most of it comes from disposable packaging. What's more,
during typhoons and severe storms, huge amounts of plastic can be swept into the sea unintentionally.
And let's face it, completely preventing this kind of leakage is nearly impossible.
That's why researchers are now racing to develop ocean-friendly materials. The ideal material,
they say, should meet three conditions. One, it's made from biomass, not fossil fuels. Two,
it's recyclable. Three, and if it accidentally ends up in the ocean, it naturally biodegrades.
透明な紙の開発
Paper already checks some of those boxes. It's made from trees, so it's biomass,
and recycling systems for paper are well established. Paperboard in particular is
widely used in the packaging, but it has one big drawback. It's white and opaque.
And let's be honest, most consumers prefer packaging that lets them see what's inside.
That's one of the reasons transparent plastics are still everywhere.
Now here comes the exciting part. The research team has succeeded in developing transparent
paperboard using cellulose, the main structural component in plants. Cellulose is actually the
most abundant natural polymer on earth made by plants through photosynthesis. Their new material
has a thickness between 0.3 and 1.5 millimeters, just like regular paperboard, but with high
transparency. To give you a sense of how clear it is, its haze value is under 30%, meaning it's
clear enough to see objects 100 meters away. And it's not just a flat sheet. They've shown
it can be molded into 3D forms like cups and straws. It's also stronger than ordinary paperboard
when wet, and doesn't need plastic coating to hold liquids. With a natural fatty acid coating,
革新的な製造プロセス
it's even water repellent. In some cases, it's stronger than polycarbonate plastic.
Even the manufacturing process is designed with sustainability in mind.
They dissolve the cellulose in the lithium biolamide solution and then recover and reuse
the solvent, meaning no liquid waste is released. This makes the whole process close the loop and
eco-friendly. And it gets better. They've shown that this material can be recycled back into the
new transparent paperboard. There's even potential for upcycling using discarded clothing or paper
waste as the raw material. This is kind of innovation we need for a circular economy.
Now here's the most important part. It's marine biodegradable. If this material ever ends up in
the ocean by accident, microbes can break it down into carbon dioxide and water. No long-term
pollution, no microplastics. But what about the deep sea where it's cold and microbes are scarce?
The team used JAMSTEC's deep sea vehicles like the Shinkai 6500 to test the material under real
deep sea conditions. And yes, it biodegrades even on the seafloor. They observed weight loss in all
透明な紙の特性
samples. Under a microscope, they saw microbes gathering on the surface, boring holes, and
breaking the material down. Using metatranscriptomic analysis, they confirmed the presence of the
enzymes that digest the cellulose. The deeper you go, the slower the process. But even at the
depths of 700 to 1000 meters, cups made from this transparent paperboard are estimated to fully
degrade in about 6 to 12 months. In fact, in Sagami Bay, at 357 meters deep, a sample was almost
completely gone in just 4 months. This is a huge step forward. The material is biomass-based,
recyclable, and marine biodegradable, checking all the boxes for the next generation of eco-friendly
packaging. Of course, there are still challenges ahead, like cutting down costs and developing
systems for mass production. But if this technology continues to evolve, it could replace plastic in
many disposable products and reduce environmental burden if they end up in the ocean. That's all
for today's episode of SciencePod. I publish new episodes every weekday morning, both in English
and in Japanese. Most of my stories focus on science and research from Japan because I want
透明紙の革新
to share Japanese innovation with the world. If you enjoyed this episode, please post your
notes or thoughts using the hashtag SciencePod. And I'm also host of Japanese science podcast
Scientalk and SciMania, and I'm passionate about supporting Japanese science podcasting.
If you want to learn more about today's topic,
check the link to the press release in the show notes. Thanks for listening and see you next time.
