The main raw material of the heating underwear is hygroscopic heat collecting fiber.
The reporter visited several large shopping malls and supermarkets in Beijing and found that many merchants are selling hot underwear. The main components of the trademark are polyester fiber and acrylic fiber. In addition, a small amount of viscose and spandex are included. The reporter found that many fever underwear claims that the fiber itself can absorb the water vapor evaporated by the body and convert it into heat energy, and the material itself will warm up.
“The concept of hot underwear is from Japan. The original thermal underwear is to improve the chemical fiber materials, mainly based on daily chemical fiber. Because the fiber absorbs moisture and heats better. In fact, there are many ways to heat up, including moisture absorption. After the heat, the use of electrical energy to heat and convert solar energy into heat, etc. Currently common on the market, the heating underwear is basically through the principle of moisture absorption and heat to achieve warmth." China Knitting Technology Committee Director Wang Zhi told reporters that in fact all Fibers have the effect of heat generation, but the degree of heat generation of different fibers is different from the level of heat generation. From the point of view of heat generation, natural materials such as wool and viscose generally have a large amount of moisture absorption, and their calorific value is greater than that of ordinary fibers. In the comparison of the heat of integration (that is, the heat generated by 1 gram of dry fiber after fully absorbing moisture), the calorific value of wool reaches 26.9 calories, which is more suitable for use in heating underwear materials.
The heating fiber was first used by the climbers.
Gong Hao, a professor at the School of Materials Science and Engineering at Beijing Institute of Fashion Technology, said that the raw material for thermal underwear is a special fiber material. This kind of fiber material is expensive. Generally, the heating underwear is made of a small amount of heating fiber with other fibers. Mostly contain viscose fiber, modal fiber, bamboo charcoal polyester fiber or recycled fiber. This fiber material was first used by climbers and later extended to the general consumer sector, mainly for the production of underwear. For example, "Sera" is actually a ceramic containing ultrafine particles added to chemical fiber acrylic fibers to make it have a heat-generating effect. "Modal fiber" is a material with a high moisture regain rate that can be converted into heat after it is absorbed.
"In recent years, foreign materials have developed a new type of fiber that can generate heat and become a material for thermal underwear. The main method for manufacturing warm heating fibers is to add special chemical components to the fibers under specific conditions. Chemical reaction produces heat. For example: Thermotron fiber - solar thermal insulation fiber, Outlast air conditioning fiber - phase change heat storage fiber, Eks moisture absorption heating fiber, Textcare nano bamboo carbon fiber and Ceramino infrared heat storage insulation fiber, etc., Tianjin Textile Yu Kun, a senior engineer at the Fiber Inspection Institute, told reporters that at present, domestic underwear manufacturers mainly use hygroscopic heating fibers as raw materials to develop knitted fabrics through different proportions and processes, and to change the thick and bloated shape of traditional warm fabrics to keep warm. The fabric is light, thin, soft and warm.
Thermal underwear is not a substitute for cotton
Ms. Li recently bought two pieces of hot underwear, but the so-called warming feeling is not obvious. In this regard, Wang Zhi explained that after the human body wears hot underwear, the hydrophilic groups in the fiber molecules combine with the moisture emitted by the human body, which will reduce the movement of human body water, thereby reducing the loss of body heat and transforming kinetic energy. , can actively raise the temperature of 2 ° C -4 ° C, but at the same time should note that even if it is really hot underwear, the temperature is also limited, the public can not use hot underwear instead of cotton jacket.
■ Purchase reminder
Recognize the "yellow black word" hot underwear logo
In December 2010, China implemented the industry standard for moisture absorption and heating underwear. For the standard of heat underwear, there are also special instruments for testing. According to industry standards, judging whether underwear meets the standards of fever underwear, there are two main dimensions: First, the peak value of the elevated temperature should be less than 3 degrees Celsius, and in addition, considering the heat dissipation and other factors, the average temperature rise within 30 minutes is greater than 2 degrees Celsius. This is the minimum threshold.
Gong Yu reminded that the publicity on the hot underwear in the market is very varied, and it is difficult to distinguish between true and false. It is difficult to define the authenticity of the hot underwear in the market only by the regulation of product performance. The China Environmental Protection Standard Research Committee is also developing a broader functional category. The relevant standards for clothing contribute to the quality specifications of different types of functional clothing. When consumers purchase hot underwear, check whether the hot underwear logo with black and yellow characters is posted on the box. This symbol indicates the name of the heating fiber, the heating effect and the proportion of addition. In addition, the purchase of hot underwear, it is best to go to regular shopping malls, supermarkets.
Common types of fever underwear in the market
Moisture absorption
The mechanism of fiber moisture absorption and heat generation is that when the fiber absorbs moisture, the hydrophilic group in the fiber molecule combines with the water molecule, and the kinetic energy of the water molecule is reduced, and at the same time, the heat energy is released. Generally, the moisture absorption and heat generation performance is closely related to the moisture regain rate. The moisture regaining rate of the fiber is good, the moisture absorption and heat generation performance is good, and the moisture regaining rate is small, the moisture absorption and heat generation performance is poor, for example, the wool and the modal fiber have good moisture absorption and heat generation effect; and the ordinary acrylic fiber and polyester have the moisture absorption and heat generation effect. Poor.
Solar heat storage
The special material is added to the fiber to absorb solar energy and convert it into heat energy, and emit a long-range infrared ray, which makes the interior of the garment warm.
Phase change heat storage
By adding a thermosensitive phase change material to the fiber, heat can be absorbed, stored, and released in the form of latent heat. In the temperature change, it can be converted into a solid liquid state, thereby achieving the effect of heat absorption and heat generation.
(different according to the principle of fever)
