The Warmth that Surpasses Down: Mizuno's "Techfill Breath Thermo" Is Amazing!

While down is lightweight and warm, it significantly loses loft and insulation properties when wet. When wearing cold-weather gear that uses synthetic down (chemical fiber down), the insulation remains relatively unaffected compared to down. This type of material is resilient against infiltration from rain or sweat, although its normal insulating performance is slightly inferior to that of down. Traditionally, it was understood that down and synthetic down have their respective advantages and disadvantages.
 
However, surprisingly, the synthetic down wear that "Mizuno" is set to unveil in autumn 2024 not only maintains better insulation when wet from rain or sweat but is also warmer than down in normal conditions. The arrival of outerwear that is consistently warmer than down is groundbreaking. Thus, I visited Mizuno Corporation and spoke with Hiroki Sakurai from the Global Apparel Product Division about the "Techfill Breath Thermo Insulated Coat" in detail.

Layers of Ultra-Thin Synthetic Down Resembling Waterfowl Feathers with Water Resistance to Enhance Insulation

Upon wearing it, the coat is light and warm. Could this warmth be attributed to Mizuno's renowned heat-generating material "Breath Thermo"? It seems a bit premature to notice a difference from the moment you put it on, considering the moisture-absorption heat-generating properties of the "Breath Thermo" material...
 
"The new functional material 'Techfill Breath Thermo' provides excellent synthetic down that surpasses down's warmth even without considering the heat-generating effect. Furthermore, it has the ability to convert moisture from the body into heat, enabling you to feel even warmer while wearing it.
 
"In many cases, insulated garments that use synthetic down maintain warmth by placing sheet-like down between the exterior and lining of the garment. The CLO value (thermal insulation value) is used as an indicator of warmth, with a higher CLO value indicating a warmer garment. It is generally known that down has a higher CLO value than synthetic down."
 
When wet, down loses loft and substantially lowers its CLO value, whereas synthetic down remains relatively unaffected. This has been the typical relationship between down and synthetic down. Mizuno has reportedly made significant efforts, including experiments in the "Environmental Testing Laboratory" at its Osaka research and development facility "Mizuno Engine," to incorporate down's advantages into synthetic down.
 
"By referencing down, we have successfully developed the synthetic material 'Techfill Breath Thermo' with unique improvements applied to sheet-like down to ensure its insulation performance surpasses that of down in normal conditions."

"At our company, we are developing new materials and technologies inspired by nature, and for the development of 'Techfill Breath Thermo,' we reexamined the warm-keeping properties of waterfowl feathers. Each feather of waterfowl is extremely light, thin, and soft. They overlap in layers, forming the overall structure.
 
"Furthermore, waterfowl frequently preen their feathers to maintain the water-repellent properties with an oil-like substance. If they neglect to preen, the feathers become susceptible to water, and their warmth retention drops when wet. By creating a very thin, light, and soft synthetic fiber filling with sustainable water-repellent properties and layering it, we can achieve a filling that offers higher warmth retention than down. Based on this research, we went through trial and error with the 'Mizuno Engine,' resulting in the ideal synthetic fiber filling 'Techfill Breath Thermo.'"
 
There are also innovations in the process of layering and molding water-repellent synthetic fiber filling. The high warmth retention depends on the amount of air (so-called dead air) held within the filling, but using adhesives during molding can compromise the space, making it impossible to hold a sufficient amount of dead air. To avoid this disadvantage, we succeeded in molding without using adhesive.
 
"First, we create an ultra-thin sheet, and 'Techfill Breath Thermo' is a synthetic fiber filling shaped using only heat without adhesives. This allows dead air to accumulate not only between the bulging fibers but also between the layers, resulting in a filling with higher warmth retention than down."

In Addition to Warmth Retention Which Surpasses Down, "Breath Thermo" Adds Heat Reneration for Extra Warmth

Up to this point, we discussed the advantages of "Techfill Breath Thermo" limited to warmth retention. Just the fact that this synthetic fiber filling exceeds down in warmth retention would be an epoch-making "event," but what’s even more impressive is that it also has heat-generating properties.
 
"Our unique heat-generating material 'Breath Thermo,' which is incorporated in a wide range of products from insulation jackets to underwear, has been developed into 'Techfill Breath Thermo' with water-repellent properties, evolving into a moisture-absorbing and heat-generating material that is strong against water. It prevents the effects of getting wet while converting steam emitted from the body into heat, enhancing warmth through the combined effects of thermal insulation plus moisture-absorbing heat generation when worn.
 
"I personally wore both down and 'Techfill Breath Thermo' during my runs for comparison. The down's insulation decreased due to sweat, leaving me feeling cold, while 'Techfill Breath Thermo' maintained its warmth even after a thorough stretch post-run."

The thoughtfully designed "Techfill Breath Thermo Insulated Coat" has the added advantage of being washable at home. It dries faster than down even when wet. According to Sakurai, hand washing and laying it flat to dry is recommended. If you're curious about this new material coat that stands apart from traditional synthetic fiber filling, be sure to try it on at a sports shop.