Anti-static is a topic with a long history. Many industry players are not aware that many previous understandings and practices have certain risks! In terms of textiles and clothing, anti-static is currently the main measure to prevent electrostatic damage.
Why should textile antistatic technology be studied?
1. Textile static electricity phenomenon and its generation principle
There are many explanations for the mechanism of static electricity. Static electricity in textile materials is mainly caused by mutual friction between surfaces. Textile materials are poor conductors of electricity and have high specific resistance. During the production, processing and use of fibers and their products, static electricity is easily generated due to factors such as friction, drafting, compression, peeling, electric field induction and hot air drying.
Especially with the increasing production and application of synthetic fibers in textiles, the inherent high insulation and hydrophobicity of these polymers make it easy to generate and accumulate static electricity.
2. Hazards of static electricity in textiles
In civilian terms, static electricity can cause dust and contamination during the use of textiles, and clothing can become entangled in the human body, causing adhesion and discomfort. Sensation, and some studies have shown that static electricity stimulation can have adverse effects on human health. In terms of industrial applications, static electricity is one of the main causative factors of fires, explosions and other accidents in the pyrotechnics, chemical, petroleum and other processing industries. It is also one of the hidden dangers of quality and safety accidents in the processing of chemical fiber and other textile industries. With the development of high technology, the consequences of electrostatic hazards have exceeded the boundaries of safety issues [3]. Spectrum interference hazards caused by electrostatic discharge can cause equipment malfunctions, signal loss and other consequences in electronics, communications, aviation, aerospace and all situations where modern electronic equipment and instruments are used. Therefore, the demand for antistatic textiles is currently increasing.
The antistatic mechanism of textiles
Static electricity on the surface of an insulator can disappear in three ways: (1) through the air (mist); (2) along the Disappears on the surface; (3) disappears through the body of the insulator.
The elimination of static electricity through the air mainly relies on the charged particles of opposite signs in the air to fly to neutralize the static electricity on the surface of the insulator or to allow the charged particles to gain kinetic energy and fly away. Using the principle of tip discharge, a high-voltage corona-type static eliminator is made, which has been applied in chemical fiber production.
The speed at which static electricity disappears along the surface of an insulator depends on the surface resistivity of the insulator. Increasing the humidity of the air can form a continuous water film on the surface of the hydrophilic insulator, coupled with the dissolution of CO2 and other impurities in the air, greatly improving the surface conductivity. A further approach is to use antistatic agents, mainly ionic or nonionic surfactants.
The leakage speed of static electricity through an insulator mainly depends on the resistivity of the insulator. Generally speaking, when the resistivity of the polymer is less than 107Ω·m, the static charge generated will leak out quickly. In order to improve the volume conductivity of polymers, the most convenient method is to add carbon black, metal powder or conductive fibers.
Fiber polymer materials are theoretically better than insulators, but the actual conductivity of fibers is higher than the theoretical estimate. The reason is that fibers are not pure polymer materials and contain low-molecular substances such as moisture and impurities, that is, Fiber conductivity mainly depends on the appendages in the fiber, and secondly on the conductivity of the fiber molecules themselves and the effects of external conditions. When the conductivity of easily ionizable substances on the surface is high and the partial pressure of water vapor is large, the conductivity of the fiber will be greatly improved.
Ways of antistatic textiles
Antistatic fabrics can be divided into two categories: civil and industrial electrostatic protective clothing. According to the end use, electrostatic protective clothing can be divided into dust-free sterile work clothes, fire-proof and explosion-proof work clothes, surgical clothes, safety work clothes (such as electrostatic protective clothing and conductive clothing worn by electric workers when working), etc.
1. Antistatic treatment of the fiber
Use surfactant to hydrophilize the fiber
The principle of action is that the hydrophobic end of the surfactant molecule is adsorbed on the surface of the fiber, and the hydrophilic polar group points to the space to form a polar surface, which absorbs water molecules in the air and reduces the surface resistance of the fiber. rate, accelerating charge dissipation. The surfactants used include cationic, anionic and nonionic surfactants. Among them, cationic surfactants have the best antistatic effect, and high molecular weight nonionic surfactants have the best antistatic effect and durability. The advantage of this method is that it is simple and easy to implement, and is particularly suitable for eliminating electrostatic interference during textile processing; the disadvantage is that the durability of the antistatic effect is poor, the surfactant is easy to volatilize, and it is not resistant to washing, and it does not show resistance in low-humidity environments. Electrostatic properties.
Blending and blending fiber-forming polymers Polymerization or graft modification
The same as the previous method is to add hydrophilic monomers or polymers to fiber-forming polymers to improve hygroscopicity, thereby obtaining Antistatic properties. In addition to the typical blending spinning method in which ordinary fiber-forming polymers and hydrophilic polymers are blended, there are also blending methods in which hydrophilic polymers are added during the polymerization process to form a micro-multiphase dispersion system. For example, adding polyethylene glycol to caprolactam reaction�, The treated fabric also has the functions of moisture absorption, anti-fouling, and non-dust absorption. Since the antistatic method is relatively simple, the price of the finished product is also relatively cheap.
The process flow is: gray cloth → padding with antistatic resin (two dips and two rollings) → drying (100~110℃) → baking (150~160℃, 2min) → tenter → finished product antistatic There are many methods of electrostatic finishing, and there are currently three main ones. (1) Additive adsorption and fixation method (2) Surface graft polymerization method (3) Low-temperature plasma surface treatment method
Since the latter two methods require more special initiators or high-energy rays or use Plasma treatment, etc., has complex processes and complex operations, so the first method is generally used. It can be used for antistatic processing in the post-finishing process or in the same bath during the dyeing process, both of which can achieve ideal results. The development status and prospects of textile antistatic technology
1. The status quo and existing problems of antistatic technology at home and abroad
At present, the antistatic technology of civil textiles Mainly use the finishing method. In electrostatic protection fabrics, conductive fibers are distributed longitudinally or transversely or simultaneously in the fabric at certain intervals to form vertical strips, horizontal strips or grids. According to the requirements of antistatic performance, the spacing range is often selected from 3mm to 15mm, because It has good wash resistance, friction resistance, heat resistance, light resistance and permanent antistatic properties, and is not affected by changes in ambient temperature and humidity. It is being increasingly widely developed and used. From the perspective of textile development, it is advisable to use conductive fibers and then undergo antistatic post-treatment to achieve excellent antistatic properties.
The problem with antistatic fabrics developed using conductive fibers is the finishing (dying, etc.) of the fabrics. Since most of the conductive fibers are dark colors, their dyeing performance becomes a problem.
2. Prospects
With the improvement of people’s requirements for clothing performance and production Considering the precision and safety, the requirements for anti-static textiles are getting higher and higher. The current anti-static technology needs to be continuously improved and improved. Judging from the current situation, the mixed use of the above-mentioned anti-static methods can achieve excellent results. antistatic effect.
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