Mechanism of far-infrared textiles

Infrared is an electromagnetic wave between visible light and microwaves, with a wavelength range of 0.75~1000μm. It can be divided into three parts: near infrared, mid-infrared and far infrared. Generally, infrared between 4~1000μm is called far infrared.

Thermal radiation is the way electromagnetic waves transfer energy, including ultraviolet rays, visible light and infrared rays. According to Kirchhoff's law, the radiation and absorption capacity of an object are proportional. The human body can emit and absorb far-infrared rays, and its main wavelength is about 10μm. Far-infrared textiles radiate 3~25μm far-infrared rays by increasing the emissivity, matching the radiation of the human body, forming resonance, raising the skin temperature, and achieving warmth and health care effects.

Far-infrared radiation material

Micropowder with far-infrared radiation performance is called far-infrared powder, which is also called far-infrared ceramic powder in China.

High-temperature far-infrared ceramic powders are mainly black ceramic powders containing Mn, Fe, Co, Ni, Cu, Cr and its oxides, SiC, etc. After heat treatment, natural tourmaline can have a higher infrared emissivity value than far-infrared ceramic powder, and the main radiation wavelength is about 9.5μm at room temperature. It also has piezoelectricity and thermoelectricity, and can release far-infrared rays through molecular vibration when the environment changes. Common low-temperature far-infrared ceramic powders are shown in Table 1;

Table 1 Common far-infrared powders

Far infrared powder for textiles is generally composed of one or two far infrared radiation substances, and has a high specific emissivity at room temperature under the skin microclimate of 35~37℃. When the content of far infrared powder is 4%~15%, it is easy to reach the extreme range of far infrared emissivity. The particle size of far infrared powder varies depending on the fiber. The particle size of far infrared powder used for filament is generally around 2μm, and that of far infrared powder used for short fiber is generally around 4μm.

Preparation of far-infrared textiles

01. Mix ceramic powder in spinning solution to produce synthetic fibers containing far-infrared ceramic powder. This method is currently used in polyester and polypropylene fibers.

02. Use finishing liquid made of ceramic powder to post-finish textiles.

Preparation of far-infrared fibers

Far-infrared fibers refer to the production of far-infrared fibers by effectively integrating some nano-powders with far-infrared emission functions with fibers during fiber processing. Table 2 lists the preparation methods and performance characteristics of far-infrared fibers.

Table 2 Preparation methods and performance characteristics of far-infrared fibers

Poly Plastic Masterbatch (Suzhou) Co., Ltd mixed ceramic powder with polyester chips to make TA10032-A1 PET dark energy storage heating far-infrared masterbatch, which was successfully used in the production of far-infrared polyester fiber. Later, through technological innovation, a new PET light-colored heating fiber masterbatch TA10114-A1 was developed. The fiber spun by this masterbatch has a light color and is easy to dye, and can be used to prepare products of various colors. According to GB/T 18319, the fiber cloth sample (containing 50% heating fiber) was tested with a maximum temperature rise of 9.9℃ and an average temperature rise of 6.6℃, which has excellent light heat storage effect.

Key performance indicators of far-infrared textiles

01. Emissivity:

Emissivity is a key indicator for measuring the radiation capacity of far-infrared textiles, usually between 0 and 1. High emissivity means stronger far-infrared radiation capacity.

02. Temperature rise:

The temperature rise index reflects the ability of textiles to increase temperature under specific conditions and is an important parameter for evaluating thermal insulation performance.

Testing standards for far-infrared textiles

According to the national standard GB/T 30127-2013 "Testing and evaluation of far-infrared performance of textiles", for general samples, the far-infrared emissivity ≥ 0.88 and the far-infrared radiation temperature rise ≥ 1.4℃ can be called textiles with far-infrared performance. For loose samples such as flakes, non-wovens, and fleece, the far-infrared emissivity ≥ 0.83 and the far-infrared radiation temperature rise ≥ 1.7℃ can be called textiles with far-infrared performance.

Application of far-infrared textiles

1. Cold-proof fabrics and winter clothing: provide good thermal insulation effect.

2. Underwear, socks and bedding: improve sleep quality and promote physical health.

3. Medical supplies: assist in the treatment of diseases such as blood circulation or microcirculation disorders.

4. Hygiene products: use its antibacterial properties to make hygiene and medical supplies, etc.