Is “heating underwear” a winter artifact or a flickering artifact? Knowing the truth, I was a little devastated

Since the winter solstice, I feel that the weather is getting colder, and the single clothes and pants have long been unable to withstand the cold wind, and the three layers inside and three layers outside are wrapped in bears and too troublesome.

So, all kinds of winter artifacts came out, searched for a certain treasure, and felt like opening the door to a new world.

The hottest of the winter artifacts is “heating underwear”, which is simply the “key” that hits many people. Since then, it seems that one dress can be “beautiful and not freezing”.

However, while being sought after, questions and doubts followed. Can fever underwear be hot? Is its warmth really as amazing as the merchant says?

Where is the “high-tech” material “high”

At present, as the temperature decreases, the sales of heating underwear have skyrocketed. After searching for “hot underwear” as a keyword on e-commerce platforms such as Taobao, Jingdong, and No.1 store, the product information reached dozens of pages, or even hundreds of pages. A fever underwear on Taobao sells more than 56,000 pieces a month. Offline, a popular brand’s HEATTECH series of heating underwear will always be out of stock due to hot sales.

There are many brands of these heat-generating underwear, with different styles and fabrics. Xiaobian found that many brands of heating underwear, the main components of their hang tags are polyester fiber (polyester), viscose fiber, modal fiber, acrylic, spandex, nylon, etc., in addition, some brands of heating underwear also in the hang tag to specifically mark the special materials used, such as “far infrared fiber”, “Selam”, “Ix”, “Outlast material”, etc., some awkward “high-tech” terms make people dazzled.

Most heating underwear businesses claim that their heating underwear has a layer of high-tech material that can heat itself and keep warm several times that of traditional cotton thermal underwear.

“Self-heating” does not conform to the law of conservation of energy

However, in the view of Zhang Tianjiao, an associate professor at Beijing Institute of Fashion Technology, the concept of “self-heating” claimed by the merchant is completely inconsistent with scientific common sense. “The concept of self-heating does not conform to the law of conservation of energy, and there must be a source of energy.” Zhang Tianjiao said.

It is understood that the concept of heating underwear originated in Japan. Around 2000, Japan introduced a special fiber material that generates heat by absorbing the moisture emitted by the human body. This fiber material was first used by mountaineers and later promoted to the general consumer field.

In fact, heating underwear is not “high-tech”. Because no matter what kind of material it is, it can generate heat by absorbing moisture. The mechanism of fiber hygroscopic heating is that when the fiber absorbs water, the hydrophilic group in the fiber molecule combines with the water molecule, and the kinetic energy of the water molecule is reduced, and it is converted into heat energy and released. Usually the moisture absorption and heating performance has a lot to do with the fiber moisture regain rate, the moisture regain rate of the fiber is large, the moisture absorption and heating performance is good, the moisture regain rate is small, the moisture absorption and heating performance is poor, such as wool, modal fiber moisture absorption and heating effect is good, while ordinary acrylic, polyester moisture absorption and heating effect is poor. The aforementioned “Exe” is a kind of hygroscopic heat-absorbing fiber, which is obtained by introducing hydrophilic groups such as amino groups such as amino groups and carboxyl groups into polyacrylic acid molecules and crosslinking treatment, which belongs to “enoate fibers”.

The heating method of far-infrared fiber is to first absorb heat and then release heat. Zhang Tianjiao said that there are two kinds of energy it absorbs: one is energy in the environment, such as visible light in sunlight, infrared, far infrared, etc., which can be absorbed by this material; Another type of energy is the heat of the environment and the heat of the human body itself. After absorbing this energy, the far-infrared fiber will convert it into far-infrared rays and then radiate to the human body, thereby providing heat to the human body. “Selam” is a kind of far-infrared radiation acrylic, which is a material obtained by adding far-infrared radiation ceramic particles to acrylic fiber using advanced spinning technology.

Zhang Tianjiao said that unlike the heating principle of far-infrared fibers, “phase change materials such as outlast materials, when the temperature of the external environment changes, these materials will undergo a phase change, just like ice melting into water, water condensing into ice.” When the temperature of the outside environment rises, it will absorb heat like ice melting into water; If the outside ambient temperature decreases, it will solidify, which is equivalent to water condensing into ice, so it will release heat again. So this is a two-way tempering material. However, Hu Guoliang, a professor at the School of Materials and Textiles of Zhejiang Sci-Tech University, pointed out that the conditions for the phase change of materials are relatively harsh, the phase transition range is relatively narrow, and only when the corresponding temperature range, such as cold to a certain degree or hot to a certain extent, the phase change material can work.

Not much different from ordinary underwear

Although fever underwear was dubbed by the merchant as a “winter artifact”, consumer Mr. Sun said in an interview with the media that he heard a friend introduce that this kind of underwear can heat itself and felt very fresh, so he spent 450 yuan to buy a set. But after wearing it, it feels no different from other thermal underwear, and it does not feel that it can emit heat on its own, and it is not as breathable as ordinary thermal underwear.

“The difference between heating underwear and ordinary underwear will not be too big, and the heating function is actually some additives inside, because the fabric itself must be a generally said textile fiber fabric, and the things that can be added are very limited, the fiber is very fine, and the functional materials added too much are easy to break, so the amount added is very small. Because the amount added is small, the effect will not be particularly obvious. Zhang Tianjiao said.

An advertising image for a “hot underwear”

At present, the common heating underwear on the market is basically to use the heat released by the human body itself, and then return it to the human body, and finally achieve a warm effect, in fact, it is not as warm as wearing one more piece of clothing.

Zhang Tianjiao said that although far-infrared fiber materials are not expensive, it is difficult to add it to fibers, which increases the cost of heating underwear; Outlast material is more expensive as a phase change material because it needs to be encapsulated in microcapsules for reuse, and this material is not widely used at present, the fundamental reason is that the effect it can achieve is not particularly significant.

It is understood that if a large amount of heating fiber materials are added, then the price of underwear becomes quite expensive. For example, NASA’s lunar landing clothing designed for astronauts uses a lot of Outlast fiber, and the low-priced “heating underwear” sold on the market actually rarely contains heating fiber.

It turns out that the heating underwear is not as good as imagined, haha! In addition to heating underwear, what other “winter artifacts” are there?

It was particularly hot some time ago

Exclusive winter artifact for the elderly.

Note that it also has a power cord underneath, but! In order to! Fill! Electricity!

I think this is pretty good.

Can make my eighty-year-old grandfather have a kind of

The feeling of riding a small motorcycle.

The only thing that is not very user-friendly is that this hand-waving shape, watching TV to change the station is too difficult, it is recommended to make the hand transparent.

I felt that the above look was a little pompous, so I found another one

Shoes with warm feet.

This shoe has a series of patterns, the upper pair is “honest”, cat lovers, there are still here