The Sort Of Anti Static Fabrics
Textile materials are electrical insulator materials, and their specific resistance is generally high, especially synthetic fibers such as polyester, acrylic and polyvinyl fibers with low hygroscopicity. Therefore, in the process of textile processing, due to the close contact and friction between fibers and fibers or between fibers and machine parts. It causes the charge to transfer on the surface of the object, resulting in static electricity. The fibers with the same charge repel each other, and the fibers with different charges attract each other. As a result, the hairiness of strips, yarn hairiness increase, wrapping forming is not good, the fibre bonding machine parts, the broken ends of yarns increase, and the scattered strips on the fabric surface are formed. When clothing is electrified, it adsorbs a lot of dust and is easy to contaminate. Moreover, clothing and human body, clothing and clothing will also entanglement or generate electric sparks. Therefore, electrostatic interference affects the smooth processing, the quality of products and the wearability of fabrics. When the electrostatic phenomenon is serious, the electrostatic voltage is as high as several thousand volts, which will cause fire and serious consequences.
It has long been found that when two insulators friction and separate each other, the dielectric coefficients of higher objects are positively charged, while the dielectric coefficients of lower objects are negatively charged. This is a law discovered at the end of the nineteenth century, which is consistent with many experimental results. The electrostatic potential sequences of various fibers obtained from experiments, such as Table 3-32 (experimental conditions are temperature and air relative humidity 33%). When friction occurs between two fibers in the table, the fibers arranged on the top of the table are positively charged and the points below are negatively charged.
Table 1 Fiber electrostatic potential sequence
Wool, nylon, viscose, cotton, silk, polyester, polyvinyl alcohol, polyacrylic, polyvinyl chloride, polyvinyl polypropylene and fluorocarbon
The first potential sequence table in 1757, which contained only wool, a textile material, was arranged near the positive end of the table. Later, many people have done research in this area. In some published potential sequences, the arrangement order of various fibers is not exactly the same, and some of them are quite different. Generally speaking, polyamide fibers (wool, silk and nylon) are near the positive charge end of the table, cellulose fibers are in the middle of the table, and carbon chain fibers are at the negative charge end of the table. It should be explained that the slight change of experimental conditions may cause the change of fibre potential. And after the textile material is charged, the potential of each part of the material is not the same. Some parts are positively charged, and some parts may be negatively charged. The situation is more complex.
The "strength" of static electricity carried by textile materials is expressed by the charged quantity (Coulomb or electrostatic unit) of the material per unit weight (or per unit area). The maximum charges of various fibers are nearly equal, but the electrostatic attenuation rates are quite different. The main factor determining the electrostatic attenuation rate is the surface specific resistance of the material. The electrostatic decay on some fabrics is half of the original value. The relationship between the half-life of electrostatic decay and the surface specific resistance of fabrics is discussed.
The logarithmic relationship between the charge half-life and the surface resistance of various fabrics is linear. The larger the surface specific resistance, the longer the half-life. Table 1 shows the relationship between the surface specific resistance and the charge half-life of some fabrics (test conditions are temperature 30oC and air relative humidity 33%). When friction occurs between two fibers in the table, the fibers arranged on the surface are positively charged and the fibers below are negatively charged.
The "strength" of static electricity carried by textile materials is expressed by the charged quantity (Coulomb or electrostatic unit) of materials per unit weight (or per unit area). The maximum charges of various fibers are nearly equal, but the decay rates of static electricity are quite different. The main factor determining the electrostatic attenuation rate is the surface specific resistance of the material.
The higher the surface specific resistance of the fabric, the longer the charge half-life. Therefore, if the specific resistance of textile fabrics is reduced to a certain extent, electrostatic phenomena can be prevented.
The production practice shows that the processing of cellulose fibers in textile mills is seldom disturbed by static electricity. Processing such as wool and silk has certain static interference. The processing of polyester fibers, nylon, polyester and other synthetic fibers is most disturbed by static electricity.
In order to solve the electrostatic interference in the wearing process of synthetic fabrics, it is necessary to make synthetic fibers and their fabrics have durable antistatic properties. There are many ways to make synthetic fibers and their fabrics durable and antistatic. For example, when synthesizing fibers, hydrophilic polymers or conductive low molecular polymers are added, or composite fibers with hydrophilic outer layers are prepared by composite spinning. For example, in the process of spinning, synthetic fibers can be blended with highly hygroscopic fibers, or positive charged fibers and negative charged fibers can be blended according to potential sequence, as well as hydrophilic additives finishing for durability of fabrics.
At present, there are three kinds of Antistatic Fabrics on the market: conductive wire antistatic fabrics, conductive fiber Antistatic Fabrics and additives finishing antistatic fabrics.