The detergency of surfactants is the fundamental property that underpins their widest practical applications. It is integral to the daily lives of countless households and is being increasingly adopted across all trades and industrial production sectors.
Antistatic Effect of Surfactants
Friction frequently generates static electricity on fibers, plastics and other finished products, impairing their service performance. For instance, static-charged textile fabrics tend to cling tightly to the body or stick to other surfaces, and easily attract dust and dirt. Static electricity exerts an even more severe impact on plastic products: not only do plastics readily adsorb dust, compromising their transparency, surface cleanliness and aesthetic appeal, but their service performance and commercial value also deteriorate.
Surfactant-based antistatic treatment is the dominant method currently employed to eliminate static buildup, and such surfactants are known as antistatic agents.
Section 1 Static Electricity and Its Generation Mechanisms
Although slight discrepancies exist in test results regarding the triboelectric charging sequence of fibers from different researchers, fibers containing amide linkages such as wool, nylon and artificial wool generally tend to carry positive charges.
The charging behaviors of common plastics are listed in Table 10-2. The triboelectric sequence of typical substances from positive to negative charge is as follows:
(+) Polyurethane – Human hair – Nylon – Wool – Silk – Viscose fiber – Cotton – Hard rubber – Cellulose acetate – Vinylon – Polypropylene – Polyester – Polyacrylonitrile – Polyvinyl chloride – Vinyl chloride-acrylonitrile copolymer – Polyethylene – Polytetrafluoroethylene (-)
The exact mechanisms of static electricity formation have not been fully elucidated, yet a consensus holds that friction between dissimilar substances induces charge transfer between the contacting surfaces, thereby generating static electricity. The polarity of the charge carried by a substance is determined by electron gain or loss: substances lose electrons and become positively charged, while those gaining electrons acquire negative charges.
Section 2 Antistatic Agents
Two primary approaches are available to eliminate static electricity:
Physical methods: Since static charge magnitude is affected by temperature and humidity, physical techniques including temperature and humidity regulation and corona discharge can be applied to remove static from material surfaces.
Surface chemical methods: Surfactants, also referred to as antistatic agents, are used to surface-treat fibers and plastic products or blended into plastic matrices to eliminate static electricity.
I. Antistatic Agents for Fibers
Required properties of qualified antistatic agents
(1) Preserve the original hand feel of fibers;
(2) Deliver outstanding antistatic performance at low dosages and remain effective under low-temperature conditions;
(3) Exhibit excellent compatibility with resin fibers;
(4) Possess good compatibility with other processing auxiliaries;
(5) Cause no foaming and leave no water stains;
(6) Non-toxic and non-irritating to human skin;
(7) Maintain stable performance over time.
Classification of fiber antistatic agents
Cationic and amphoteric surfactants constitute the main categories of antistatic agents for fiber applications.
Antistatic mechanisms
Surfactants exert antistatic effects on fabrics through two core pathways: inhibiting static generation during frictional contact and facilitating the dissipation of surface static charges. The suppression of frictional charging is closely correlated with surfactant molecular structure, whereas charge dissipation depends on the adsorption capacity and hygroscopicity of surfactants on fiber surfaces.
Cationic surfactants readily adsorb onto negatively charged fiber surfaces via their intrinsic positive charges:
① They neutralize the inherent surface charges of fibers;
② Cationic surfactants attach to fibers through positively charged quaternary ammonium groups, with hydrophobic hydrocarbon chains oriented outward, forming an ordered adsorbed film on fiber surfaces. This film effectively reduces surface friction during contact and mitigates frictional static buildup.
For low-polarity, highly hydrophobic synthetic fibers, cationic surfactants adhere to fiber surfaces via van der Waals forces acting on hydrophobic hydrocarbon chains, while polar quaternary ammonium groups face outward. This coats fibers with a hydrophilic polar layer that boosts surface electrical conductivity and moisture retention, accelerating the dissipation of friction-induced static electricity and delivering antistatic functionality.
The adsorption capacity of dioctadecyl ammonium chloride on natural fibers is markedly higher than that on synthetic fibers, indicating superior antistatic efficacy for natural fiber substrates.
Like cationic surfactants, amphoteric surfactants bear positive charges and adsorb onto negatively charged fiber surfaces to neutralize static charges, with their hydrophobic moieties lowering surface friction. Unlike cationic surfactants, amphoteric molecules contain an additional anionic group, which further enhances surface moisture absorption and charge dissipation capabilities. Amphoteric surfactants thus serve as high-performance antistatic agents, albeit at a higher cost.
Anionic and nonionic surfactants demonstrate weak antistatic performance due to low adsorption levels on fiber surfaces. Nonionic surfactants adsorb more readily than anionic surfactants because their adsorption is unaffected by fiber surface charge, yet they offer poor charge dissipation, resulting in far inferior antistatic capacity compared to cationic and amphoteric surfactants.
II. Antistatic Agents for Plastics
Mechanism of surfactant-based plastic antistatic agents
Surfactants bind to plastic surfaces through van der Waals forces acting on hydrophobic hydrocarbon chains, with polar functional groups extending outward to form an oriented adsorbed film. This film imparts surface conductivity to enable efficient static charge dissipation and simultaneously moderates surface friction on plastic substrates.
Classification by surfactant chemical type
(1) Anionic surfactants
(2) Cationic surfactants
(3) Amphoteric surfactants
(4) Nonionic surfactants
Classification by application method
(1) Coating-type antistatic agents (applied to material surfaces)
(2) Melt-blended antistatic agents (mixed into plastic raw materials during compounding)
Post time: Jul-16-2026