世界で最も白い塗料
Hello everyone, SCIENSPOT is a podcast that shines a spotlight on the latest scientific
technology from Japan. Your host is REN from SCIEN-TALK. Today's SCIENSPOT, we are going
to focus on the world's whitest paint developed by Purdue University in the United States.
And today's episode is part of the monthly SCIENSPOT guest day. Our topic for this discussion
is color. So why is this paint attracting so much attention? While conventional white
paints typically reflect only 80% to 90% of sunlight, this paint boosts an astonishing
ability to reflect 98.1% of solar radiation. Imagine a building becoming a super mirror
that almost completely deflects sunlight. What's even more crucial is its innovative
cooling ability. It can keep the coated surface cooler than the ambient air temperature.
Global warming is one of the most pressing challenges facing modern society. This paint
is regarded as having immense potential as a passive cooling technology, offering an
alternative to active cooling systems like air conditioners that consume electricity.
It's like envisioning buildings themselves starting to breathe cool air. This technology
is expected to significantly reduce electricity consumption and associated carbon emissions,
thereby contributing to the realization of a sustainable society.
Now let's explore why this paint is not just incredibly white, but also capable of
バリウム硫酸の効果と冷却メカニズム
cooling. This secret lies in its composition and cooling mechanism. The main component
of the initial version is barium sulfate. While this is a common white pigment used
to photographic paper and cosmetics, the key to this paint's effectiveness is the different size
distribution of its particles. Imagine various sized pinballs bouncing light in different
directions. Similarly, different sized barium sulfate particles efficiently scatter a wide
range of solar wavelengths, including ultraviolet, visible, and near-infrared light,
achieving that incredible 98.1% reflectivity. Unlike titanium dioxide pigments typically used
in conventional paints, which absorb UV light and heat up surface, barium sulfate absorbs almost
no UV light, enabling its superior cooling performance.
And the most revolutionarily cooling mechanism of this paint is known as passive radioactive
cooling. This technology not only reflects sunlight with extremely high efficiency,
but also simultaneously actively emits infrared heat from the coated surface
directly into outer space. It's as if the building has a special heat vent
designed to release warmth toward the cosmos. The emitted infrared radiation is specifically
engineered to match a particular wavelength range known as the sky window, 8 to 13 micrometers,
which the atmosphere is transparent to. This allows the heat to propagate efficiently directly
塗料の冷却性能
into the ultra-cold deep space without being absorbed by our atmosphere.
Though this mechanism, the paint emits more heat than it absorbs from the sun,
consequently allowing the coated surface's temperature to drop below the ambient air
temperature. This fundamentally distinguishes it from conventional paints that merely block heat.
The actual cooling performance is remarkable. Outdoor tests have demonstrated that even
under direct sunlight during the day, the coated surface remains up to 4.5
degrees Celsius cooler than the ambient temperature. Furthermore, at night, it can
maintain a surface temperature that is up to 10.5 degrees Celsius lower than the surrounding air.
This is a huge benefit for regions suffering from heat waves during hot summer nights.
Notably, reports indicated that even in outdoor tests conducted in a cold
temperature of approximately 6 degrees Celsius during winter.
This paint continues to evolve, and Purdue University has developed a thinner,
lighter new formulation aiming for application in transportation equipment
where weight directly impacts performance, such as aircraft, automobile, and trains.
This new version uses hexagonal boron nitride as the primary pigment, which is about half
the density of barium sulfate, making the entire paint 80% lighter.
It also achieves 97.9% solar reflectance with a very thin film thickness of about 150 micrometers.
最も白いペイントの多様な応用
The applications of this paint extend beyond just building roofs and exterior walls.
In addition to the aircraft, automobiles, and trains we just mentioned,
and the professor is also considering its application to clothing,
shoes, and even portable electronic devices like mobile phones.
Imagine wearing clothes that keep you cool in summer,
or smartphones that maintain optimal temperature even under heavy use.
This truly points to the future where heat management solutions become ubiquitous
in every aspect of our lives.
The environmental impact is also immeasurable.
According to statistical models conducted by Purdue University researchers,
applying this paint in hot U.S. cities is estimated to reduce air conditioning usage by up to 70%.
This not only saves us money on electricity bills,
but also suppresses the burning of fossil fuels for power generation,
thereby directly reducing carbon dioxide emissions.
Moreover, extreme simulations by researchers estimate that covering just 0.5% to 1% of the Earth's
surface with this ultrawide paint would be sufficient to halt the trend of global warming.
This area is vast, equivalent to slightly more than half of the Sahara Desert,
but it illustrates the potential scale of its impact.
However, it's important to remember that experts from the University of California,
Davis, have raised significant concerns that covering such a vast area could threaten wildlife
技術と地球温暖化の関係
and disrupt weather patterns, and scoring the necessity
of careful evaluation for large-scale implementation.
So this world's whitest paint is not just a technology with record-breaking performance,
it holds immense potential to contribute to reducing energy consumption in our daily lives
and combating global warming on a planetary scale.
Currently, corporate partnerships and patent applications for commercialization are underway,
and while a widespread market release of specific products hasn't been confirmed as of 2025,
so the focus of research and development is shifting from mere performance maximization
to solving real-world challenges.
That's all for today's science spot, and as I mentioned at the beginning,
this episode is a special contribution to the Science Podcast Day event.
If you're interested in science discussion in Japanese,
please check out other podcasts from the links in the description box.
This podcast is broadcasted early on weekday morning in both Japanese and English.
I'd love for you to listen to the podcast and post your notes and thoughts with the hashtag
ScienceSpot.
Thank you for listening.
See you next time.
