Fibres antistatic finishing

Most non-polymeric antistatic finishes are also surfactants that can orient themselves in specific ways at fibre surfaces. The hydrophobic structure parts of the molecule act as lubricants to reduce charge buildup. This is particularly true with cationic antistatic surfactants that align with the hydrophobic group away from the fibre surface, similar to cationic softeners (see Chapter 3, Fig. 3.1). The main antistatic effect from anionic and non-ionic surfactants is increased conductivity from mobile ions and the hydration layer that surrounds the hydrophilic portion of the molecule since the surface orientation for these materials places the hydrated layer at the air interface. 

The performance of most antistatic finishes depends on the kind of fibre and sometimes also on the kind of fabric (anisotropic behaviour, for example, different... 

Synthetic fibres take a static charge because they are non-conductive and only absorb small quantities of water. This effect is reinforced by low air humidity, particularly in winter, and soiling may be increased. Antistatic finishings reduce the high electrical resistance of fibres. These consist of hydrophilic surface active polar compounds (tensids), carbon particles, electrically guiding polymers or salts. Textiles may also be made antistatic by incorporating metallic or metallised fibres or conductive carbon fibres which are coated with polyamide. 

A fibre protection agent, providing retexturing and antistatic finish for (hying, is also added automatically. 

Antistatic agent can also be called antistat in the industry. The best antistatic agents used in fibre finishes are quaternary amines and alcohol phosphate esters. For example, A-cetyl-A-ethylmorpholinium ethylsulphate shown in Fig. 5.8a and stearyl alcohol phosphate shown in Fig. 5.8b are representative antistats. 

A typical spin-finish concentrate would consist of lubricant (usually blended), 75-85%, antistat, 5-10%, and additives (antioxidants), 5-10%. Formulations of textile machine lubricants based on water-soluble PAGs combine gear lubricity with ease of removal from fibres during processing. 

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