Applications of Fluorocarbon Plasma Technology in the Textile Industry

　　Plasma treatment using fluorocarbon compounds introduces fluorine-containing functional groups, yielding low-energy surfaces that endow materials with a range of specialized properties. This approach finds applications across diverse fields and constitutes an important strategy for material modification.

　　Application of Low-Temperature Plasma Technology with Fluorinated Gases in the Textile Industry

　　Compared with the traditional wet‑processing techniques used by textile printing and dyeing enterprises, plasma treatment, as an effective surface‑treatment method, represents a highly promising clean‑production technology. Both domestically and internationally, research on the application of plasma processing to textiles has primarily focused on the following areas: enhancing the spinning performance of wool fibers; improving the dyeing and printing properties of fibers; increasing the anti‑felting and shrinkage resistance of wool; deepening the coloration of dyed fabrics; boosting the adhesion and interfacial strength between fibers and polymer matrices; and enhancing the effectiveness of fabric pretreatment. The process gases commonly employed include oxygen, nitrogen, air, and argon.

　　Durable water- and oil-repellent multifunctional finishes for textiles are commonly achieved using organic fluoropolymer resins, as reported extensively both domestically and internationally. By employing plasma treatment to introduce fluorinated functional groups, durable water- and oil-repellent multifunctional finishes can be imparted; however, research in this area remains relatively limited.

　　Plasma treatment with fluorinated gases can enhance the water- and oil-repellent properties of various fibers. Yasuda treated fabrics made from common fibers—such as polyester, nylon, vinylon, cotton, polyamide, wool, and silk—with a CF4 plasma; after treatment, the contact angles of the fabrics improved to varying degrees, surface tension decreased, and the fabrics exhibited excellent water- and oil-repellency. Additionally, some researchers have employed fluorinated monomers to carry out plasma polymerization on cotton and acrylic fabrics, imparting superior water‑repellent performance. Moreover, the resulting cotton fabrics outperformed those coated with commercial Scotchlite water‑ and stain‑repellent agents in terms of softness, moisture retention, color stability, hand feel, and breathability.

　　Various gases can be used as plasma‑treatment atmospheres, including mixtures of CF4, C2F4, C3F6, and H2. All these gases enhance the fabric’s water‑repellent properties, with the degree of repellency varying according to the type of fluorocarbon employed, the treatment duration, and the applied power. When different gases and operating conditions are used to treat distinct fabrics, the surface fluorine content differs markedly, and the introduced fluorinated functional groups also vary. For example, treating nylon with a CF4 atmosphere yields a surface fluorine content of 1–2%, whereas treatment with C3F6 results in a surface fluorine content of 2.3–7.8%. X‑ray photoelectron spectroscopy (XPS) reveals that CF4 plasma treatment induces fluorination on the fiber surface, introducing fluorinated functional groups; analysis of the C 1s spectra shows increases in –C–O–C–, –CF–, –CF2–, and –CF3– groups, while –COH– and –COOH– groups decrease. Moreover, the predominant functional groups introduced differ among fabrics: for polyester, nylon, vinylon, and cotton, the main introduced group is –CF2–, whereas natural protein fibers such as wool and silk exhibit strong absorption at the –CF– region. Notably, C3F6 delivers superior treatment performance compared to CF4.

　　The durability of the treatment effect is one of the key indicators for evaluating its quality. Some reports have noted that fabrics treated with plasma exhibit a time‑dependent effect, whereby the hydrophilic properties acquired gradually diminish over time. However, when polyester fabrics were subjected to CF4 plasma treatment, it was observed that even after 150 days of storage, no significant change in the F/C ratio was detected, nor was there any noticeable degradation in their water‑repellent performance. Research has shown that the molecular structure of the gas used is a critical factor influencing the durability of the fabric‑treatment effect. Fabrics treated with gases containing unsaturated structures display poorer durability compared to those treated with saturated‑structure gases. This may be attributed to the fact that unsaturated gases tend to undergo polymerization during plasma treatment, and the resulting polymers do not adhere strongly to the fabric surface.

　　The hydrophobicity imparted by plasma treatment diminishes after washing and drying. This is because, upon laundering, the fluorinated groups on the fiber surface readily reorient, increasing the surface tension and thereby reducing the fabric’s water-repellent performance. However, high‑temperature drying following washing can help restore the fabric’s hydrophobic properties.