The detergency of surfactants is a fundamental property that gives surfactants their most practical uses. It is involved in the daily lives of thousands of households. Moreover, it is increasingly applied in various industries and all kinds of industrial production.
Antistatic effect of surfactants
Fibers, plastics, and other products often generate static electricity due to friction, which affects the application performance of their products. For example, if fiber fabrics carry static electricity, they often have drawbacks such as “clinging to the body” or “static adhesion”, as well as being prone to absorbing dust or getting dirty. The impact of static electricity on plastic products is even greater. Not only do the products easily attract dust, affecting their transparency, surface cleanliness and appearance, but they also reduce the usability and value of the products.
To eliminate this static electricity phenomenon, the surfactant antistatic method is mostly used at present. Such surfactants are called antistatic agents.
- Electrostatic phenomena and their causes
Although there are some differences in the results obtained by different researchers regarding the order of fiber electrification, fibers with amide bonds such as wool, nylon, and artificial wool tend to be positively charged.
The common electrical charging status of substances, from positive to negative, is as follows: (+) Polyurethane – Hair – Nylon – Wool – Silk – Viscose Fiber – Cotton – Hard Rubber – Acetate Fiber – Vinylon – Polypropylene – Polyester – Polyacrylonitrile – Polyvinyl Chloride – Vinyl Chloride – Acrylonitrile Copolymer – Polyethylene – Polytetrafluoroethylene (-). Although the cause of static electricity generation is not yet fully understood, it is generally believed that when different types of objects rub against each other, moving charges are generated between the rubbed objects, thus producing static electricity. The type of charge an object carries can be determined by the gain or loss of electrons. If an object loses electrons, it becomes positively charged; if it gains electrons, it becomes negatively charged.
- Antistatic agent
There are two main methods to eliminate static electricity:
Physical method: Since the magnitude of static electricity is affected by temperature and humidity, physical methods such as adjusting temperature and humidity, and corona discharge can be used to eliminate static electricity on the surface of objects.
Surface chemical method: That is, using surfactants, also known as antistatic agents, to perform surface treatment on fibers and plastic products or to blend them into plastics to achieve the purpose of eliminating static electricity.
2.I. Antistatic agents for fibers
Conditions that antistatic agents should meet:
(1) Do not change the hand feel of the fiber;
(2) Good antistatic effect, small dosage, and still effective at low temperatures;
(3) Good compatibility with resin fibers;
(4) Good compatibility with other additives;
(5) No foaming phenomenon and no water stains;
(6) Non-toxic and non-damaging to the skin;
(7) Can maintain good stability.
2.2. Types of antistatic agents
The main types of antistatic agents used for fibers are cationic and amphoteric ionic surfactants.
2.3. Mechanism of action of antistatic agents
The antistatic mechanism of surfactants used for fiber antistatic mainly manifests in two aspects: preventing the generation of static electricity when the surface of fiber fabrics is rubbed and the dissipation of surface charges. Preventing frictional electrification is closely related to the structure of surfactants; while the dissipation of surface charges is related to the adsorption amount and hygroscopicity of surfactants on fiber fabrics.
Cationic surfactants can easily adsorb to the surface of negatively charged fibers through their own positive charges.
① It can neutralize the surface charge of the fiber;
② Since cationic surfactants adsorb to the fiber surface with positively charged quaternary ammonium ions, and the hydrophobic hydrocarbon chains face outward, forming an oriented adsorption film composed of hydrocarbon chains on the fiber surface. This adsorption film can effectively reduce the friction force generated on the fiber surface during friction, thereby weakening the frictional electrification phenomenon.
For synthetic fibers with low polarity and strong hydrophobicity, cationic surfactants adsorb to the fiber surface through van der Waals forces with their hydrophobic hydrocarbon chains, while the polar quaternary ammonium groups face outward, covering the fiber surface with hydrophilic polar groups. This not only increases the conductivity of the fiber surface but also increases its surface humidity, which is beneficial to the dissipation of static electricity generated by friction and plays an antistatic role.
The adsorption amount of dioctadecyl ammonium chloride on the surface of natural fibers is significantly higher than that on synthetic fibers. This indicates that it has a better antistatic effect on natural fibers.
Like cationic surfactants, amphoteric ionic surfactants carry positive charges and can also adsorb on the surface of negatively charged fibers to neutralize static charges. Their hydrophobic groups also have the effect of reducing friction. Moreover, compared with cationic surfactants, they have an additional anionic group in their molecular structure, so they can better increase humidity and charge dissipation. Therefore, amphoteric ionic surfactants are antistatic agents with good performance, but their price is relatively high.
Anionic and non-ionic surfactants have poor antistatic effects due to their low adsorption amount on the fiber surface. The adsorption amount of non-ionic surfactants is higher than that of anionic ones because it is not affected by the surface charge of the fiber, but their effect on static dissipation is poor, so their antistatic ability is far worse than that of cationic and amphoteric ionic surfactants.
- Antistatic agent for plastics
Mechanism of action of surfactants as antistatic agents for plastics: Surfactants adsorb on the plastic surface through van der Waals forces with their hydrophobic hydrocarbon chains, while their polar groups extend outward, forming an oriented adsorption film of surfactants on the plastic surface. This film provides conductivity, allowing static charges to dissipate well. At the same time, the adsorption film can also reduce friction on the plastic surface.
Plastic antistatic agents are classified according to the type of surfactant into:
(1) Anionic type;
(2) Cationic type;
(3) Amphoteric ionic type;
(4) Non-ionic type.
Antistatic agents can be divided into two categories according to their method of use:
(1) Surface-coated antistatic agents;
(2) Compounding-type antistatic agents.
Post time: Mar-12-2026