Wool surface treatment technology uses physical, chemical, and biological methods to treat wool in order to reduce felting. "The felting shrinkage of wool fibers decreased after treatment." Currently, there are many surface treatment technologies for wool fibers, each with its own advantages and disadvantages.
Biotechnology: Currently, the main biotechnology for treating wool fibers is enzyme treatment. Enzymes are favored by the textile industry due to their specificity and high efficiency. However, enzyme treatment of wool fibers is still in its early stages, and the effects of enzyme preparations are not entirely satisfactory. Cultivating bio-enzyme products with significant effects, good environmental adaptability, and stable composition for specific treatments has become an urgent priority. Zhu Huajun et al. studied the effects of dichloroisocyanurate, protease, and MTG enzyme treatment on the strength, alkali solubility, and friction coefficient of wool fibers. The results showed that the first two reagents damaged the wool fibers, causing a decrease in fiber breaking strength, a decrease in the surface friction coefficient, and an increase in alkali solubility. After treatment, the fibers showed a slight recovery in strength after MTG enzyme processing. However, the repair effect on the untreated sample was weak. With increasing MTG enzyme dosage and treatment time, the reinforcing effect of the enzyme on the fiber surface... The slight difference in surface finish initially strengthens and then weakens.
Physical Methods: Physical methods for processing wool fibers include plasma treatment and wool stretching and refining techniques. Plasma is an ionized gaseous substance composed of positive and negative ions generated from atoms and atomic groups that have lost some electrons. When energetic particles in plasma impact the material surface, the energy is lost, and the material surface is modified. The energy exchange between plasma and materials mainly occurs through radiation and particle collisions. Low-temperature plasma technology is a processing method that uses only plasma as the exciter and fiber as the object of treatment. No waste products are left in this process; the reaction only occurs on the fiber surface, not only not affecting the fiber's inherent properties but also imparting new characteristics to the fiber surface. The energy released during the reaction process is enormous, enabling the achievement of goals that traditional chemical methods cannot accomplish at lower temperatures. However, this method also has some drawbacks: it requires many factors to set the experimental reaction conditions, is highly dependent on the processing equipment, the reaction process is relatively complex, and some technical aspects of the processing equipment are... The issues still require further adjustment and improvement, and cannot be industrialized; therefore, it remains only at the laboratory stage. After plasma treatment, the wettability, breaking strength, and color yield of wool fabrics are all improved.
Wool Stretching and Refining Technology
Wool stretching and refining technology is a technology that is harmless to humans and nature. The process can be simply summarized as follows: chemical reagents are used to break specific target chemical bonds in the fiber; the chemically pretreated product is stretched using physical methods to straighten the molecular chains, and then permanently fixed using a wet heat method. Currently, there are three stretching and refining methods for wool fibers: untwisted short-spacing grip stretching (grip stretching), false-twisted large-spacing grip stretching (twisted stretching), and true-twisted short-spacing grip stretching (composite stretching). After treatment, the surface scale structure of the fiber is destroyed, making the fiber softer; the length and strength are improved compared to ordinary wool fibers, and the fiber stiffness is reduced compared to ordinary wool, making it suitable for developing high-count, lightweight fabrics. In the 1980s, the Commonwealth Industrial Science Research Institute of Australia began exploring the possibility of wool refining, pioneering... This technology pioneered the field. Researchers worldwide have since conducted long-term and in-depth studies in this area. While stretched and refined wool possesses properties not found in ordinary wool, several production challenges remain: large length dispersion, a small base number of main fibers, and some wool fibers exhibit rapid dyeing after stretching, leading to dyeing batch variations and color differences between the inner and outer layers of the wool clumps. Currently, there is limited literature related to the stretching and refining process.
Chemical Methods Chemical methods for finishing wool fibers include nanomaterial modification, chemical degradation, and polymer deposition.
Nanomaterial Modification When the particle size of the original material is processed to a certain order of magnitude (nanoscale), the atomic structure and crystal morphology of the surface change, resulting in unique effects distinct from macroscopic matter: surface effects, small size effects, etc. When the number of atoms on the particle surface increases, the surface energy increases, producing stronger surface effects and chemical activity. This is because there are no atoms to bind with it, leading to an excited state. This surface atomic activity can both cause changes in the surface structure of nanoparticles and... It can cause changes in the surface electron spin conformation and electron energy spectrum. The specific surface area and surface effects generated by nanomaterials can give them significant chemical activity and surface adsorption. In the nanomaterial modification process, nanoparticles are uniformly distributed in a solvent and react with some free groups on the scale structure of wool fiber surface, allowing the nanoparticles to persistently accumulate on the wool.
Zhu Yue et al. investigated the effect of silver-loaded nano-SiO2 on the tribological properties of ultrafine wool, forming a durable antimicrobial nanolayer on the surface of wool fibers. Scanning electron microscopy revealed that the ultrafine wool had a certain thickness of antibacterial layer, and the fiber surface became smooth. Testing of the single fiber strength and tribological properties before and after the experimental treatment yielded the following results: the fiber surface was uniform after treatment; its fracture resistance was improved; the tribological properties of the test samples were significantly improved, reducing pilling and felting phenomena, and weakening the felting properties of wool fibers. However, some problems existed in the experiment: the nanoparticles used were irregular in morphology, and the incorporation of nanoparticles caused an increase in the fiber's reverse friction coefficient. Attention should be paid to the amount of nanoparticles bound to fibers.
Chemical Degradation Technology: During wool processing with oxidants (hydrogen peroxide, manganese oxide, sodium dichloroisocyanurate, etc.), specific types of target chemical bonds in keratinized cells break, increasing the number of charged groups or soluble molecules in the keratin layer; hydrophilicity increases, thus softening the scales, leading to a decrease in the difference in friction coefficients between the co- and anti-co ... Hydrogen peroxide, potassium permanganate, and sodium dichloroisocyanurate were used to treat mutant cashmere fibers. The changes in tensile strength, friction properties, and surface morphology of four treated textile fiber samples were tested to analyze the interference of different oxidants on the scale structure and function of mutant cashmere fibers. Hydrogen peroxide showed a relatively mild effect, with a tensile strength loss of less than 5%. Potassium permanganate and sodium dichloroisocyanurate treatments yielded similar results, with significant effects, reducing tensile strength by approximately 15%.
Polymer Deposition Method
Polymerization Polymer deposition is a method of reducing friction by depositing polymers onto fiber scale layers. Its anti-felt shrinkage principle mainly involves three mechanisms: After adding a small amount of polymer, cross-linking occurs between the fiber scale structures, causing them to adhere and preventing relative fiber displacement; After adding an appropriate amount of treatment material, a thin film forms on the fiber surface, covering or completely encapsulating the scales; After adding an excessive amount of treatment material, the polymer encapsulating the fibers completely isolates them. However, in actual processing, most of the reagents or products used are solvents that are harmful to the environment or ecology, thus affecting its application prospects. Zhou Wu addressed the problems of felting and pilling in cashmere and wool products by using two methods: chemical grafting with methacrylamide and treatment with M-501 polyurethane for surface modification of cashmere. By analyzing the effects of these two surface modification methods on cashmere fiber properties, the experiment explored the degree of interference between the two polymer deposition methods and the functional properties of cashmere fabrics. The experimental objective was to determine the performance indicators of cashmere and wool fibers obtained at different mass concentrations.
Development Trends of Wool Fiber Surface Treatment Technology
Currently, fiber surface modification treatment... Most methods involve chemical treatment. However, this treatment damages the fiber matrix, wastes significant resources during production, and causes substantial environmental pollution. Therefore, effectively and environmentally friendly fiber surface treatment has become a current research hotspot. Current domestic research faces the following main problems: ① The selection of reagents for fiber surface modification is still under exploration; the effects of reagents used in the same experimental types have not been compared to select the most suitable reagents. ② Unlike macroscopic research, the setting of factors and levels in microscopic experiments directly affects changes in the fiber scale structure and may even damage the dermis, causing instability in fiber friction properties. Therefore, more precise experimental schemes are needed. In the future development of wool fiber surface treatment technology, when a single technology cannot meet the requirements, researchers should combine different wool fiber treatment technologies. This can both compensate for the shortcomings of each treatment technology and discover new properties of wool fibers. With the advancement of science and technology, the rapid development of microscopic technologies will bring new breakthroughs to fiber surface treatment technology.
