Heating fibers and their products
With the improvement of people's aesthetic and comfort requirements, light and thin fabrics which can heat and keep warm for a long time are increasingly favored, thus promoting the development of heating fibers.
Heating fiber is a new type of fiber which can generate heat and keep warm by itself. It can not only prevent heat emission like traditional fibers, but also absorb and store external heat and transmit it to the human body. As far as the heating mechanism is concerned, the main types of heating fibers are light energy heating, electric energy heating, phase change heating, chemical heating and hygroscopicity heating.
Light heating fiber
Absorbing Far Infrared Light and Heating (Far Infrared Fiber)
Generally, it is made by evenly adding far infrared absorption material (ceramic powder) into polyester and polypropylene fibers. Ceramic powders are mostly metal oxides, such as alumina, magnesium oxide, zirconia, and sometimes titanium dioxide and silicon dioxide are also used. For example, some heat storage and thermal insulation polyester fibers have infiltrated far infrared absorption materials into the internal structure of the fibers (amorphous zone) evenly in the post-processing process, which can improve the absorption of sunlight and other external infrared rays, and play a thermal storage and thermal insulation effect.
Other insulation fibers are made by adding infrared absorbers and glass beads to polymers. The internal temperature of the clothing made of this kind of fibre is 3-7 C higher than that of the ordinary fabric.
Heating by absorption of visible and near infrared light
You will also find that some fibers have zirconium carbide particles dissolved in their core, which emits heat under the action of sunlight and heat energy and reflects long-wavelength far-infrared rays, thus warming the interior of clothing. There are also some fibers whose core layer contains micro-semiconductor particles (tin oxide and antimony oxide composite powder) that can absorb near-infrared rays, which can directly convert light energy into heat energy.
Electric heating fiber
Electric energy heating fibers are composite fibers containing components of electric heating materials. The principle of electric energy heating fibers is through conductive fibers to achieve heating effect. At present, carbon fibers are widely used as conductive fibers. Carbon fiber material has the function of producing far infrared rays when heating, besides its rapid heating and high electrothermal conversion rate. Therefore, it can be used to develop heating and warming clothing with both health functions. In addition, some underwear series products use very fine silver fibers and small rechargeable batteries which can be powered. They can also achieve better thermal insulation at very low external temperatures.
Chemical Reaction Heating Fiber
Chemical substances are added to the fibers, and chemical energy is converted into heat energy by exothermic chemical reaction, so as to achieve the heating effect. If iron powder is blended into polymer for spinning, it can be oxidized and exothermized by oxygen in air to keep warm. But the biggest problem of this kind of products is that the heating effect is not ideal and the durability is poor. Warm sticker is an application of this kind of fiber.
Phase change temperature regulating fiber
Based on the principle of absorbing or releasing heat during the phase transition of substances, the body microenvironment temperature is regulated in two directions. It can absorb heat at higher ambient temperature and release heat at lower ambient temperature. Phase change temperature control fibers are thermal sensitive phase change materials wrapped in microcapsules. With the change of temperature, solid and liquid phase change into each other, so as to achieve the effect of heat absorption and exothermy.
Hygroscopic and heating fibers
Natural fibers have certain hygroscopicity and heat-generating properties, especially wool fibers. Generally speaking, the thermal properties of hygroscopically heated fibers are related to their moisture regain rate. If the moisture regain rate is high, the hygroscopically heated fibers are excellent; on the contrary, the hygroscopically heated fibers are poor. Inspired by this, people have developed hygroscopic and heating fibers.
The mechanism of moisture absorption and heat generation of fibers is generally believed to be that when the fibers absorb water, the fibers and water molecules attract each other and bind, and the kinetic energy of water molecules is reduced and released into heat (energy). In addition, in order to enhance the heating effect, a substance can be added inside the fiber or coated on the surface of the fiber. When the fiber absorbs water, it triggers the chemical reaction of the substance to release more heat.
