Moisture absorbing property is an important aspect of clothing comfort and an important indicator of reflecting the new concept of a healthy and comfortable life. This article introduces the development of moisture-wicking and quick-drying fibers, and focuses on analyzing the processing methods of moisture and heat comfort fabrics, providing a basis for the development of functional textiles.
The Development of Moisture-wicking and Quick-drying Fibers
The research and development of moisture-wicking and quick-drying fibers are mainly achieved through two methods, physical modification, and chemical modification. The former refers to the production of fibers with grooves on the surface by changing the shape of the spinneret micro-holes. By utilizing the capillary principle, the fibers can quickly transport, diffuse, and evaporate water, removing moisture and sweat from the skin surface and releasing them to the outer layer for evaporation. Alternatively, a method of blending spinning or composite spinning with polymers containing hydrophilic groups (hydroxyl, amide, carboxyl, amino, etc.) can be used to produce fibers with moisture-wicking and quick-drying properties. The chemical modification involves grafting and copolymerization to introduce hydrophilic groups into the macromolecular structure, thereby increasing the fiber’s moisture-wicking and quick-drying properties.
The physical modification includes three methods: changing the shape of the spinneret holes, blending the spinning of raw materials, and bicomponent composite spinning.
Changing The Shape of The Spinneret Holes
DuPont developed the high moisture-wicking four-groove polyester Coolmax fiber. Toyobo, a Japanese textile company, developed the Y-shaped cross-section polyester “Triacotr,” which has three moisture-wicking grooves on its surface. Far Eastern Textile developed Topcool moisture-wicking and quick-drying fibers. Guangdong Zhujiang JinFang Group developed moisture-wicking and dry polyester filament by changing the fiber’s cross-sectional shape. The increased surface area and capillary effect greatly improve its moisture-wicking performance. Jiangsu Yizheng Chemical Fiber Co., Ltd. designed the Coolbest fiber by producing fibers with an “H” shaped cross-section. Taiwan Chung Shing Textile Co., Ltd. produces “Coolplus” fibers with Y-shaped and cross-shaped cross-sections. Taiwan Haojie Company developed Technofine fibers with a W-shaped cross-section. Donghua Haite Company produces cool dry fibers. Shunde Jinfang Group and Donghua University cooperated to develop Coolnice moisture-wicking polyester fibers with a cross-sectional shape of “+”.
Blending Spinning Of Raw Materials
Asahi Kasei Corporation developed high moisture-absorbing and quick-drying polyurethane fibers, which have the characteristics of high moisture absorption and fast moisture release. They can quickly release steam and sweat to the outside, maintaining a comfortable feeling. Teijin Corporation developed WELLKEY polyester hollow fibers, which have many interconnected pores inside and outside, and liquid water can penetrate from the fiber surface to the hollow part. Wang Rui et al. blended conventional PET chips with water-soluble polyester (EHDPET) chips in a ratio of 85/15 to 80/20 to produce blended fibers with hollow micropores and surface irregularities. The “Sipulon” fiber developed by the Institute of Chemistry of the Chinese Academy of Sciences is an ultra-fine fiber with a unique core absorption effect, but its regain rate is only 0.03%. Due to the increased surface area of the fabric and the fine fiber diameter, the gap between single fibers is small, so high-density fabrics do not need to be waterproofed and have good waterproof and breathable functions.
Bicomponent Composite Spinning
The composite spinning of polyester and other hydrophilic polymers using a twin-screw extruder is used to study the new type of moisture-wicking fiber with a skin-core composite structure and an irregular cross-section. The water absorption and appearance of the fiber are improved, with the hydrophilic material as the core layer and conventional polyester as the skin layer. The two components play the roles of hydrophilic moisture absorption and moisture-wicking, respectively. The new high moisture-absorbing and quick-drying fiber HYGRA developed by Japan’s Unichika Corporation is a composite fiber with a skin-core structure. The skin layer of the fiber is made of conventional nylon, which feels smooth and cool when wet and has superior moisture absorption and release capabilities compared to cotton fibers. Japan’s Kuraray Company developed the sophistic fiber using a composite spinning method, with the surface layer made of EVOH with hydrophilic groups (one OH) and the core layer made of polyester.
By grafting copolymerization, hydrophilic groups are introduced into the macromolecular structure to increase the moisture-wicking function of the fiber. Carboxyl, amide, hydroxyl, and amino groups are usually introduced to increase the affinity for water. In addition to modifying the raw materials, appropriate spinning processes are required to give the fiber a porous structure and a larger specific surface area.
Ekslive, a breathable polyester fabric developed by Toyobo, achieves moisture-wicking by blending polyacrylate powder with polyester fibers, which absorb moisture and removes heat, improving the saturation water absorption of polyester fabrics. Komatsu Serien Company grafts silk compounds onto polyester fibers to produce moisture-wicking polyester. Xu Bi et al. treated cotton fabrics with nano-silica and then reacted with dodecyltrimethoxysilane to make them hydrophobic. Eef Temmerman used low-temperature plasma discharge to treat cotton yarn to improve its capillary effect. Soon Cheon Cho et al. used low-temperature plasma to graft hexamethyl disiloxane onto cotton fabrics to make them water-repellent.
The Development of Moisture-wicking Fabric
Processing Method of Moisture-wicking Yarns
Currently, there are two main types of moisture-wicking yarns with fast-drying functions: simple yarns and composite yarns. Simple yarns can be divided into staple yarns and filament yarns depending on the fiber type.
Processing methods include multi-fiber blending, twisting, and special finishing. Developing and using moisture-wicking yarns with good moisture-wicking properties is an important way to develop moisture-wicking, quick-drying, and cool fabrics.
Generally, the performance of moisture-wicking fibers is difficult to balance between moisture absorption, moisture-wicking, and moisture release, which limits the moisture-wicking and quick-drying performance of fabrics. Therefore, blending fibers with moisture absorption and moisture-wicking properties is a simple and effective way to improve the dryness and comfort of fabrics.
Twisted yarns can be produced by twisting single yarns or filaments with different moisture absorption and moisture release functions, which can obtain yarns with both moisture absorption, moisture-wicking, and moisture release functions. For example, blending cotton fibers with moisture absorption properties and Coolmax filaments with moisture-wicking and moisture-release properties can produce composite yarns with moisture absorption, moisture-wicking, and quick-drying properties.
Multi-layer Structured Composite Yarns
Multi-layer structured composite yarns can be produced by using different forms or types of fibers and advanced spinning technology to distribute the yarns in a multi-layer structure, which is beneficial to exert the performance of different components and achieve the goal of moisture-wicking and quick-drying.
Moisture-wicking fabrics are designed to change the moisture absorption, transfer, and release properties of fabrics through fabric structure design or fiber modification, making them water-absorbent and quick-drying. Currently, there are both knitted and woven fabrics with moisture-wicking and quick-drying functions, which can be classified into single-layer, double-layer, and multi-layer fabrics according to their structures.
With the rapid development of post-processing technology, various functional fabrics have emerged. Moisture-wicking and quick-drying finishing, which was born to meet the requirements of clothing for wet and hot comfort, improve the fabric’s ability to transfer sweat and solve problems such as sweating difficulties and discomfort caused by heat.
Single-Layer Unidirectional Moisture-Wicking Fabric
In the early stages of research and development, single-layer fabrics were first considered, usually made of pure or blended yarns of moisture-wicking and quick-drying fibers. In recent years, with the advancement of processing technology, fabrics with unidirectional moisture-wicking ability have been developed. Unidirectional moisture-wicking fabrics refer to fabrics with different moisture absorption and release properties on the front and back or inner and outer layers of the fabric. When sweat contacts the fabric and the skin surface, moisture-wicking has strong directionality, and sweat can be continuously transported from the close-fitting side to the outer layer and evaporated, keeping the skin dry and comfortable. Therefore, theoretically, the moisture-wicking and quick-drying ability of this unidirectional moisture-wicking fabric and its dryness performance when in contact with the skin will exceed that of fabrics with consistent hydrophilic and hydrophobic properties on both sides.
Wang Nanfang et al. used a printing method to perform unidirectional hydrophobic finishing on pure cotton knitted fabrics, which had strong wash resistance. Compared with untreated fabrics, the air permeability decreased by about 10%, and the fluffiness decreased by 5% to 7%. Wu Jihong et al. first performed water-repellent finishing on yarns, then wove and dyed them to prepare moisture-wicking knitted fabrics, but the water-repellent treatment of yarns had complex weaving processes and was prone to color bleeding during fabric dyeing, resulting in high processing costs. Wu Yefang et al. achieved moisture-wicking and quick-drying effects on cotton fabrics through single-side finishing, but the air permeability of the coated fabrics decreased, affecting their wearing performance. Tianhong et al. used single-side finishing technology to develop double-sided moisture-wicking and quick-drying pure cotton knitted fabrics.
Double-Layer Or Multi-Layer Single-Direction Moisture-Guiding Fabrics
The development of double-layer or multi-layer single-direction moisture-guiding fabrics has been influenced by people’s desire to return to nature and their preference for cotton fibers. However, the swelling and blocking of fabric gaps caused by the wetting and swelling characteristics of cotton fibers can hinder the heat and moisture exchange between the human body and the external environment. The absorption of moisture by cotton fibers can also cause heat release. As the moisture absorption reaches saturation, the heat release will gradually stop, and the evaporation of water in the fabric will instead absorb the heat from the surface of the human body, causing a feeling of stuffiness followed by dampness and coldness.
In recent years, the development of double-layer or multi-layer structured fabrics has laid the foundation for the development of single-direction moisture-guiding fabrics. These fabrics usually use hydrophobic synthetic fibers as the inner layer of the fabric and have three main structural types.
Hydrophobic Fibers For The Inner Layer And Hydrophilic Fibers For The Outer Layer
The first type of fabric structure involves using hydrophobic fibers for the inner layer and hydrophilic fibers for the outer layer. The inner layer is usually made of synthetic fibers, while the outer layer is made of natural fibers. The fabric’s inner layer comes into contact with the skin, and its characteristic is that gaseous sweat can be absorbed by natural fibers or other moisture-absorbing fibers, while liquid sweat can be transferred to the surface layer through the capillary effect of the inner layer’s synthetic fibers and absorbed by the moisture-absorbing fibers on the surface layer before being released into the outside air. Because the fabric only comes into contact with the skin at certain points, the inner layer of the fabric remains dry, creating an insulating layer of air that keeps the wearer warm and comfortable even after sweating, without feeling sticky, stuffy, or cold.
The widely used cotton-polyester composite knitted fabric is a typical example of this type of fabric. The bottom yarn of the cotton-polyester composite fabric is made of hydrophobic polyester yarn, while the surface yarn is made of hydrophilic cotton yarn. After being treated with hydrophilic agents, the fabric has the characteristics of rapid moisture absorption and quick diffusion to the outer layer of the fabric, keeping the inside of the clothing dry. Research by Wang Xiao and others has shown that the thermal insulation and dryness of fabrics with a cotton outer layer and a hollow polyester inner layer are better than those of fabrics with both layers made of cotton fibers. They also have a more obvious effect of absorbing sweat and drying quickly than fabrics made of ordinary yarns with hydrophilic properties. When the content of hydrophobic fibers on the surface is 30%, the fabric’s moisture absorption and dryness performance are the best.
Different Types of Hydrophobic Fibers for Inner and Outer Layers
This fabric is made of synthetic fibers, and the inner and outer layers use different specifications or types of hydrophobic fibers. Its water absorption mechanism is different from that of natural fibers and is achieved by shaping the capillary effect of the inner and outer layers differently, which is also known as the “cedar effect.” Typically, the surface layer is made of fine fibers, while the inner layer is made of coarse fibers. Because the capillary pressure of the surface layer fibers is greater than that of the inner layer fibers, there is an additional pressure difference between the surface layer and the inner layer, which facilitates the transfer of sweat from the inner layer to the surface of the fabric and its evaporation into the environment through the outer layer, keeping the surface of the fabric’s inner layer relatively dry and the wearer feeling comfortable. The Airfine Field Sensor multi-layer knitted fabric produced by Japan’s Toray Industries is a typical example of this structure, which can quickly absorb sweat from the human body and spread it from the inner layer to the surface layer, with moisture absorption and quick-drying ability twice that of the Field Sensor sweat-absorbing knitted fabric. It is commonly used in sportswear, medical and healthcare clothing, and workwear.
Composite Structured Fabric With Wick-Like Absorption Points
It is a new type of knitted fabric with a high sweat transmission rate. This fabric also consists of two layers, namely the hydrophobic permeable layer (inner layer) and the absorbent layer (outer layer), which are combined with many connecting points. The connecting points are made of yarn and are shaped like wicks, distributed in a predetermined order throughout the fabric, and contain hydrophilic fibers (such as cotton fibers) that penetrate both layers of the fabric.
The Czech Bnro Knitting Research Institute has developed various natural-colored cotton wick-layered fabrics and conventional air-layered fabrics using the Japanese Fukuhara V-LEC4BS computerized jacquard double-sided weft knitting technology. Hou Qiuping and others have developed a double-sided fabric with polyester and polyester-cotton blended yarn for the inner layer and brown-colored cotton for the outer layer. They designed three types of fabrics with wick-like points distributed at densities of 50%, 25%, and 12.5% of the fabric, respectively. The moisture transmission performance test results showed that when the materials of the inner and outer layers of the fabric are completely the same, the smaller the density of the wick-like points, the better the moisture transmission performance of the fabric. Gu Zhaowen and others designed a wick-like point structure moisture-wicking and quick-drying knitted fabric with a high transmission rate using H-shaped cross-section moisture-absorbing and quick-drying polyester fibers and colored cotton fibers. They also studied the effect of hydrophilic finishing on the fabric’s performance. The results showed that when the materials of the inner and outer layers of the fabric are completely the same, the smaller the density of the wick-like points, the better the permeability and dryness performance of the fabric. After hydrophilic treatment, the permeability and quick-drying performance of the fabric decreased, indicating that this type of fabric is not suitable for hydrophilic treatment.
The moisture and heat transfer performance of clothing is an important factor in maintaining human thermal balance and comfort. If sweat cannot pass through the fabric smoothly, the humidity and temperature in the microclimate between the human skin and clothing will increase, and the human skin surface will be wrapped in high temperature and sweat, causing discomfort. Therefore, it is necessary to process fabrics with moisture-wicking and quick-drying properties.
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