Diverse Applications of Surfactant Products in the Textile Industry

Since the 1940s, surfactants have gained extensive applications in industrial production, earning them the nickname "industrial MSG." Surfactant molecules possess amphiphilic properties, making them easily concentrate at the surface in aqueous solutions, significantly altering solution properties. The properties exhibited vary with the proportion of hydrophilic and hydrophobic components, as well as the molecular structure. They have a range of physicochemical properties such as dispersion, wetting or anti-sticking, emulsification or demulsification, foaming or defoaming, solubilization enhancement, washing, preservation, and antistatic performance. These fundamental properties are crucial in various stages of textile processing, including fiber refining, spinning, weaving, dyeing, printing, and finishing.

According to statistics, there are over 3000 varieties of surfactants used in the textile industry, and they play a crucial role in processes such as refining loose fibers, spinning, yarn spinning, weaving, dyeing, printing, and finishing. Their functions include improving textile quality, enhancing yarn weaving performance, and reducing processing time, making surfactants a significant contribution to the textile industry.

Applications of Surfactants in the Textile Industry

Leveling Agents and Dispersants:Leveling agents delay dye absorption by fibers during dyeing, preventing uneven coloring. Surfactants, such as sodium alkyl sulfonates and sodium alkyl sulfate, can be used as fiber-affinitive leveling agents for natural and nylon fibers. Non-ionic surfactants, like alkyl polyethylene glycol ethers, are used in reduction dyeing and dispersion dyeing.

Softeners:Softeners, mainly surfactants, are used to impart a durable and smooth feel to fabrics after pre-treatments like scouring. Anionic softeners were used earlier, and cationic surfactants, particularly quaternary ammonium compounds, are widely used for their excellent softening, antistatic, and bactericidal properties.

Antistatic Agents:Antistatic agents, especially anionic ones like alkylphenol polyethylene glycol ether sulfates, are crucial to prevent or eliminate static electricity during textile processes. Cationic surfactants serve as effective antistatic agents with additional softening and fiber adhesion properties.

Penetrating Agents and Wetting Agents:Penetrating agents and wetting agents, primarily anionic and non-ionic surfactants, facilitate rapid wetting and penetration of liquids into fibers. They are essential in processes like scouring, refining, silk glossing, and bleaching.

Dispersing Agents:Dispersing agents are indispensable in dye processing and application, with anionic surfactants being common, such as naphthalene sulfonate formaldehyde condensates and lignosulfonates. Non-ionic surfactants, like alkylphenol polyethylene glycol ethers, are also used in combination with other surfactants.

As various new dyeing technologies mature, such as microwave dyeing, foam dyeing, digital printing, and supercritical fluid dyeing, higher demands are placed on leveling agents and dispersants.

Fabric Softeners:Before dyeing and finishing, fabrics generally undergo pre-treatments like scouring, resulting in a rough feel. Fabric softeners, mostly belonging to surfactants, are employed to provide a lasting smooth and soft feel to the fabric. Anionic fabric softeners were used earlier, and non-ionic fabric softeners, such as fatty alcohol polyethylene glycol ethers, are applied in the post-processing of cellulose fibers and as softening and smoothing components in synthetic fiber oil formulations.

Cationic surfactants have strong binding capabilities with various fibers, withstand high temperatures and washing, and provide durable softness. They are crucial in fabric finishing, offering a full and smooth feel, antistatic effects, and excellent bactericidal and disinfection capabilities. Cationic surfactants, mostly nitrogen-containing compounds, include tertiary amine salts and quaternary ammonium salts, with dimethyl dihydrogenated tallow ammonium chloride being a prominent softening agent. However, its larger size and difficulty in biodegradation pose environmental challenges.

The next generation of environmentally friendly products often incorporates surfactants with hydrophilic groups, such as ester or amide groups or hydroxyl groups. These surfactants can be easily biodegraded by microorganisms into C18, C16 fatty acids, and smaller cationic metabolites, minimizing environmental impact.

Antistatic Agents

To eliminate or prevent static electricity generated during various processes in the textile industry or during fabric finishing, antistatic agents are essential. Their primary function is to impart moisture-absorbing and ionic properties to the fiber surface, reducing fiber insulation, enhancing conductivity, and neutralizing charges to eliminate or prevent static electricity. Among surfactants, anionic antistatic agents have the most diverse varieties. Sulfonates of fats, fatty acids, and high carbon fatty alcohols exhibit antistatic properties along with softening, lubricating, and emulsifying capabilities. Alkyl naphthalene sulfonates, especially ammonium and ethanolamine salts, demonstrate high antistatic efficiency among anionic antistatic agents.

Generally, cationic surfactants not only serve as highly effective antistatic agents but also offer excellent smoothness, softness, and fiber adhesion. However, they have drawbacks such as dye discoloration, reduced sunlight fastness, incompatibility with anionic surfactants, metal corrosion, high toxicity, and skin irritation. Therefore, their usage is restricted and primarily employed in fabric finishing rather than oil formulations. Cationic surfactants used as antistatic agents mainly belong to two categories: quaternary ammonium compounds and fatty acid amides. Amphoteric surfactants, such as betaines, not only exhibit excellent antistatic effects but also provide lubrication, emulsification, and dispersion.

Non-ionic surfactants have strong hygroscopicity, making them suitable for low humidity conditions in fibers. They generally do not impact dyeing performance, can adjust viscosity over a wide range, exhibit low toxicity, and cause minimal skin irritation. As a result, they are widely used and constitute important components in synthetic oil formulations. Non-ionic antistatic agents primarily include fatty alcohol polyethylene glycol ethers and fatty acid polyethylene glycol esters.

Penetrating Agents and Wetting Agents

Penetrating agents and wetting agents are additives that facilitate rapid wetting of fiber or fabric surfaces by water and penetration into the fiber's interior. Surfactants capable of promoting liquid penetration or accelerating surface adsorption into porous solids are termed penetrating agents. Penetration is contingent on prior wetting. Wetting refers to the degree of liquid spreading on the solid surface upon contact. Therefore, penetrating agents and wetting agents find application not only in pre-treatment processes such as scouring, boiling, silk glossing, and bleaching but also extensively in printing and finishing processes.

Characteristics required for penetrating agents and wetting agents include: 1) resistance to hard water and alkali, 2) strong penetrating ability to reduce processing time, and 3) significant improvement in capillary action of treated fabrics.

Cationic surfactants are unsuitable as wetting agents since they adsorb onto fibers, hindering wetting. Amphoteric surfactants have certain limitations in application. Therefore, surfactants used as penetrating agents and wetting agents are primarily anionic and non-ionic. Additionally, in the textile industry, surfactants find applications as scouring agents, emulsifiers, foaming agents, smoothing agents, fixing agents, and water repellents, among others.