Surprisingly Cool Despite Far-Infrared! What Is the Next-Generation Functional Material "TERAX COOL" Born from Flipping the Script?

When you hear "far-infrared," you might imagine something like a Kotatsu or a heater—things that "warm you to your core." But what if that far-infrared could actually bring "coolness" in sweltering heat?

There’s a product that unravels the science behind far-infrared mechanisms and applies it for cooling performance. That’s the next-generation functional material "Toko Shoji Co., Ltd." calls "TERAX COOL."

Why was it possible for far-infrared to deliver a function opposite to what we’d expect, by providing cooling? We interviewed Director Mikio Toyama and R&D Department Manager Yumika Sato to learn their secrets and the story behind its development.

The Idea for Terahertz Ore Came from an Unexpected Product

The company, alongside their group company Toko Limy Co., Ltd., has long served not only as a textile wholesaler but as a bridge connecting factories and customers. While searching for functional materials in various fields, starting with sportswear, they stumbled upon an unexpected discovery.

"Around 2014, while searching for standout winter clothing, we realized that vests and jackets with heating sheets were gaining popularity, so we immediately began an investigation." (Toyama)

However, many products on the market raised safety concerns, like broken heating wires or faulty batteries in those heating sheets. The team started exploring a safer heating method that didn’t rely on heating wires, and began looking into semiconductor technology to radiate far-infrared rays.

"By printing a powder made mainly from terahertz ore onto fabric, we discovered that not only the parts in contact but the entire body feels warm. Since it doesn’t use heating wires, it’s extremely safe to wear." (Toyama)

At the time, printing powder onto fabric was a groundbreaking idea. But why did they focus on minerals?

"While doing business overseas, we discovered that in China, sheets containing terahertz ore were being used. Apparently, these were developed to help truck drivers stay comfortable while spending nights in their vehicles. That sparked our idea, and we went on to make further improvements ourselves." (Toyama)

The Direction in which Far-Infrared is Reflected is Key

The precursor to the "TERAX COOL" we’re covering this time was actually a product developed for winter cold protection. But how did their research into warming materials end up creating something that produces a sensation of coolness—the polar opposite?

"We already knew that minerals radiate far-infrared, so we were studying the synergistic effects of mixing different minerals together. That’s when we realized: if we could direct the far-infrared radiation outward from the body, maybe we could expel body heat more efficiently." (Sato)

It took considerable time to research the heat-retaining "TERAX HOT" from scratch. However, once they had the idea of "reflecting far-infrared rays in a certain direction," the development of "TERAX COOL" moved forward rapidly.

The Meaning Behind Printing Minerals Instead of Spinning Them into Threads 

When it comes to giving fibers functionality, it's more common to modify the thread itself rather than use prints. However, there was a compelling reason for deliberately choosing printing.

"For the 'TERAX' series, we process minerals into a powder and print them onto the fabric. While we also considered blending the mineral powder directly into the thread, experimental data showed that printing yields better results." (Sato)

"Printing also offers the major advantage of accommodating small production runs. If we used thread, we'd have to blend several raw materials and produce large quantities to be profitable." (Toyama)

If there's a difference in effectiveness, then printing clearly has the edge. However, for the "TERAX" series, since the entire surface of the fabric is printed, it raises concerns about texture and comfort. In reality, the team overcame these obstacles with meticulous calculations.

"We've adopted a pattern based on octagonal shapes. This technique leaves some areas unprinted, ensuring breathability. Of course, the print locations can be freely changed according to clients' requests." (Sato)

Proof of Functionality Through Empirical Data

Attention to materials is important, but it's meaningless unless the effects are truly realized. In this regard, there is also reliable, objective data to back up their claims.

The company not only conducts its own experiments but also requests independent verification from third parties, solidly demonstrating the advantage of their materials. 

Comfort for Both Commuting & Exercise

Given the high functionality of these materials, it's easy to envision "TERAX COOL" items being extremely popular during summer. Since the benefits work best when touching the skin directly, the core product line is based around undershirts, but a diverse range of items such as leggings and arm covers are available to meet various needs.

"In recent years, what we call 'extremely hot' summers are lasting longer, so the demand for 'TERAX COOL' stays high year-round. Many people use it for UV protection from sunlight, so we offer not only short-sleeve but also long-sleeve undershirts, which have been particularly well received by women.

"Additionally, our company supplies products to field workers and has products placed in yoga studios, allowing many customers to experience the high effectiveness themselves." (Sato)

In addition to the two primary functions of heat dissipation and heat shielding, quick-drying and UV protection support indoor and outdoor activities, which is key to their popularity.

Using New Raw Materials to Help Prevent Heatstroke

Though the effects of "TERAX" have been clearly verified, what are their plans for future developments? We asked this as our final question.

"Because the color of the minerals inevitably transfers to the fabric during processing, we're now focusing on silica obtained from rice husks to achieve a completely transparent product. We're exploring whether we can use this to create materials with the same heat dissipation and heat shielding properties as 'TERAX COOL.'

"Of course, we want to continue expanding the reach of 'TERAX' technology, but we are also putting energy into developing businesses that branch off from it. One of these focuses is heatstroke prevention measures.

"About three years ago, several employees became certified as heatstroke prevention instructors. This way, as we introduce 'TERAX,' we can also hold events to share advice on maintaining a comfortable lifestyle." (Sato)

"TERAX COOL" brings a cooling sensation via far-infrared rays, potentially transforming how we live. Toko Shoji's activities, which extend support not only to clothing but to people's daily lives overall, embody the company's philosophy of "a more comfortable lifestyle."