microfiber is mainly divided into superfine natural fiber and superfine synthetic fiber. Superfine natural fiber mainly includes animal fiber (spider silk, silk, leather, animal hair, etc.), plant fiber, etc. Superfine synthetic fibers are mainly polyester, polyamide, polyacrylonitrile, polypropylene, polytetrafluoroethylene and glass fiber and other fiber varieties, the largest output in the industry is polyester and polyamide two kinds of superfine fibers. [2]
Super fine natural fiber
1. In order to survive and develop, the organism in nature has created a series of optimal composition and structure under the impetus of the external environment, so that the organism has special structure and function to adapt to the environmental changes of nature. Spider, for example, in most circumstances out of wire diameter 0.5 1.0 mu m, good tenacity, elongation at break of 14%), a better ability to bear heavy or strong external shocks, can be used for the preparation of soldiers wearing body armor and shield of the military machinery, can also be used in aerospace, construction, medical and health care and other fields, has great potential application value. Silk is another important kind of natural protein fiber, which is composed of silk fibroin and sericin coated around silk fibroin. Each silk is composed of two single fibers side by side. After degluing, the linear density of fiber is 1.1~1.3 dtex, and the strength of silk is high, the elongation at break can reach 15%~25%, and the wear resistance is better than other natural fibers. It also has important application in medicine, textile and military field. In addition, animal fur (the diameter of wool fiber microfiber is 10-15nm) and the linear density of fibrils in the cortex are both less than 1.1dtex, which are the main reason for the excellent performance of natural skin and become the preferred object of bionic research and artificial cortex manufacturing. [2]
2. Plant fiber In addition to animal fiber, plant fiber is another excellent natural fiber, mainly distributed in the sclerophyte tissue of seed plants, the basic composition is cellulose, by 7000~10000 glucose molecules by glycoside chain linked polymer. As an outstanding representative of superfine natural plant fiber, cotton fiber has a diameter of 10-17μm, and the diameter of the smallest unit of cotton fiber – microfiber is about 6nm. It is widely distributed on the surface of plant seeds and is an important raw material for theoretical research and industrial application in textile industry. In addition, in the plant stem, some hemp herb stems. For example, ramie, jute, flax, etc., have developed fiber bundles, fiber diameter between 10~ 40μm, as an important source of industrial textile raw materials. [2]
Superfine synthetic fiber
Human beings have found many inspirations from the development and evolution of natural organisms and developed many superfine synthetic fibers. They are soft, excellent draping, and comfortable to wear. They are the focus of research and development of superfine fibers in various countries around the world. The major varieties of synthetic fibers in the industry, such as polyester, polyamide, polyacrylonitrile, polypropylene, etc., can be obtained through certain technical means of ultrafine fiber varieties. At present, the industrial promotion of superfine polyester is more mature than other fibers, and it plays a leading role in textile fibers. [2]
Feature editing broadcast
The most remarkable characteristic of microfiber is that its filament density is much lower than that of conventional fiber, and the smallest fiber can reach 0.0001 dtex. Because of this remarkable characteristic, microfiber has many different properties from ordinary fiber, which are mainly listed as follows: [1]
(I) Feel soft and delicate with good flexibility [1]
The cross section diameter and fineness of the monofilaments of the superfine fiber are smaller than those of the natural fiber, so its crimp modulus is lower, so the fabric has better feel softness. Its monofilament has low bending stiffness, so its fabric has good drape property. Compared with ordinary fiber, microfiber has higher crystallinity and orientation, which improves the relative strength of fiber, so the bending strength and repeated bending strength of fiber are improved, making it flexible, smooth, and soft to the touch. However, these properties are also related to the fabric structure, mix fiber composition, mix fiber ratio and so on. At the same time, for textured yarns, the reduction of monofilaments fineness will lead to poor fluffiness. [1]
(2) Good wrinkle resistance and wear resistance [1]
The decrease of the fineness of the microfiber reduces its absolute strength, but for the same yarn size, the number of fiber roots in the yarn section is more than that of the conventional yarn, so the strength of the yarn is still relatively high. At the same time, it is helpful to sand wash or pile up the fabric, so as to prepare high grade fabrics like velvet, suede and peach velvet, and has better wrinkle resistance and wear resistance. [1]
(3) Good fluffiness and soft luster [1]
The microfiber is small in fineness and high in density, which increases the specific surface area and capillary effect of the fiber. It not only improves the covering and fluffy of the fabric, but also disperses the reflection of light, so that the reflection of light inside the fiber is more delicate, so that the luster is soft and makes it have the luster of silk. [1]
(4) High-density fabric structure and high cleaning capacity [1]
Superfine fiber in the fiber thin, warp/weft yarn in weaving easily cling to each other and extrusion deformation, thus it is easy to form a high-density fabric, the warp/weft density is several times of ordinary fabric, after finishing, even do not make any coating processing, such as preparation of waterproof fabric, the fabric can be used in a raincoat, windbreaker, casual wear, sportswear, dust-free cloth, fashion and shoe fabric, etc. Also, because of its smaller monofilament density, with its weaving cloth to wipe the object, slender fiber is like a sharp knife, making it easy to scrape off the dirt, at the same time, the superfine fiber and contamination of the contact surface is larger, and therefore easier to stick close, and have very strong capillary core utility, thus easy to adhesion of dirt into a fabric, To avoid the re-pollution of objects due to the dispersion of dirt, so it has high cleaning capacity, is the ideal choice for wiping cloth and clean cloth. [1]
(5) Good heat preservation [1]
Microfiber is small in fineness and there is more still air in the fiber collection body, so microfiber is a better thermal material. If some coarse fibers are mixed into the fiber collection body as a scaffold, its compressive elasticity and fluffiness can be greatly increased. [1]
(6) High water absorption and oil absorption [1]
The fineness and specific surface area of the superfine fiber become smaller and larger, thus forming smaller and more capillary holes, which not only greatly improves the hygroscopicity of the fabric, but also greatly improves its capillary core absorption capacity, so that it can absorb and store more liquid (oil or water). Therefore, microfiber can be applied to the development of high water absorption products, such as high water absorption pen, high water absorption towel and other products. These pores absorb a lot of water, so microfibers are highly absorbent, and most of the water they absorb is stored in the pores, which can be dried quickly, effectively preventing bacterial growth. [1]
(7) Good carriers of biological enzymes and ion exchange interest [1]
Because of the large specific surface area of microfibers. Therefore, it is a good carrier of active agents such as biological enzymes and ion exchangers, which can improve its activity efficiency. Moreover, it can also be used in osmotic membranes, biomedicine (such as artificial skin and artificial blood vessels) and other fields. [1]
In addition, microfiber also has resistance to microbial adhesion and shellfish, seaweed corrosion and other properties. However, there are some problems in the process and use of microfiber. Such as: the friction coefficient is large, the monofilament strength is low, the bending stiffness decreases, so that the stiffness of the prepared fabric is reduced, the fluffiness decreases; Due to the large specific surface area, it is difficult to desize, absorb more pulp, large amount of dye and uneven dyeing. Therefore, dyeing and finishing equipment and related technological conditions need to be adjusted properly in the process of processing and preparation. [1]
Preparation method edit broadcast
Conventional microfiber preparation
The conventional microfiber is mainly divided into filament and short filament, and the spinning form is also different according to the fiber type. The main spinning forms of conventional microfiber filament are direct spinning and compound spinning, while the main spinning forms of conventional microfiber short filament are conventional fiber alkali reduction method, jet spinning method and blending spinning method, etc. [2]
1, direct spinning method is the use of traditional melting spinning process, using a single raw material (polyester, nylon, polypropylene, etc.) to prepare ultrafine fiber spinning technology, simple process, convenient operation, but the fiber preparation process is easy to produce broken, spinneret hole is easy to plug. [2]
2, composite spinning method is the use of composite spinning technology to get composite fiber, and then the use of physical or chemical treatment method to make the composite fiber polyphase separation, and then get ultrafine fiber, the success of composite spinning technology marks the real beginning of the development of ultrafine fiber. [2]
3, the conventional alkali reduction method is mainly aimed at polyester fiber, using dilute alkali treatment of polyester fiber to achieve the purpose of refining the fiber. [2]
4. Jet spinning method this method mainly takes polypropylene as the spinning object, spraying the polymer melt with low viscosity into short fibers by jet flow. [2]
5, blending spinning method is the method of blending two or more than two kinds of polymer materials for spinning, due to the difference between the content of different components and viscosity and other physical characteristics, the use of solvent can achieve the separation between components, get discontinuous ultrafin short fiber. [2]
Preparation of nanofibers
With the development of the research and the improvement of the detection and characterization methods, the fiber diameter can be further refined (<100nm) to the nanometer level. Compared with the conventional preparation process of ultrafine fibers, the preparation methods of nanofibers are various. Nanofibers can be divided into inorganic nanofibers and organic nanofibers. The preparation methods of the two nanofibers are quite different. [2]
For inorganic nanofibers, the main synthesis methods include arc evaporation, laser high-temperature burning and compound pyrolysis. The diameter of carbon nanotubes is less than 0.4 nm and has excellent antistatic properties. However, the processing performance of inorganic nanofibers is poor, which needs further research and exploration. [2]
Preparation of organic nanofibers For organic nanofibers, there are mainly two preparation methods: composite spinning and electrostatic spinning. [2]
(1) composite spinning technology is Japan toray company in 1970, the development of a used in the manufacture of artificial suede microfiber method, the method USES the special distribution under different components of polymer in molten state, and then through the jet orifice tensile extrusion, sea island was made by the fiber, fiber of a component ACTS as a "sea", another set of specific provisions for the "island", After the fiber is made into a finished product, the composition of the sea is dissolved to get the nanofiber. Toray has successfully used this method to produce nanofibers with diameters less than 100nm. [2]
(2) Electrostatic spinning technology, namely polymer jet electrostatic stretch spinning, is a new fiber preparation technology completely different from conventional spinning. The basic principle is that when the applied electric field is applied to the surface of capillary liquid, the polymer melt or solution will have a large amount of electrostatic charge. With the increase of electric field force, the polymer melt or solution will overcome its surface tension and form a small jet flow. During the injection process, the solvent volatilizes and solidifies, eventually forming a collection of microfibers on the receiving device. These fibers are typically less than 100nm in diameter and have a continuous structure. Because of its simple operation, wide application and low cost, electrospinning has become a research hotspot in the field of nanofiber spinning. [2]
Application editing broadcast
(1) Imitation silk fabric: the level of superfine fiber imitation silk and other natural fibers (wool, cotton, hemp) is getting higher and higher, and the simulation effect is more and more realistic, even to the degree of imitation. [3]
(2) Imitation peach skin fabric: this is a kind of garment fabric with excellent quality and unique style. The peach leather fabric is made of superfine fiber, with very short fuzz on the surface, just like the short fuzz on the surface of peach, soft, delicate and warm. The high-end fashion, jacket, T-shirt, underwear and culottes woven with this material are cool and comfortable, absorbing sweat and not close-fitting, rich in youth and beauty. [3]
(3) High water absorption materials: mainly used for high water absorption towels, paper towels, pen reels, sanitary napkins, diapers, etc. It is reported that the high absorbent towel developed by Japan's Small material Pharmaceutical company absorbs water more than 5 times faster than ordinary towels, and feels very soft and comfortable when it is used more quickly. [3]
(4) High density waterproof and steam permeable fabric: the high density fabric woven by superfine fiber has both waterproof effect, steam permeable and moisture permeable, light and easy to fold and carry. Microfiber clothing for skiing, skating, swimming and other sports can reduce resistance and help athletes create good results. [3]
(5) clean cloth and dust-free cloth: ultrafine fiber can absorb dust, particles and liquid 7 times its own mass. Clean cloth made of superfine fiber has strong cleaning performance, cleaning is fast and thorough, and does not lose hair, can be reused after washing, in precision machinery, optical instruments, microelectronics, clean room and family and other aspects have been widely used, is also the ideal choice of dust-free clothing. [3]
(6) Suede and artificial leather: Made of superfine fiber knitted fabrics, weaving machine, the grinding processing wool or hair after dipping in the polyurethane solution, and the dyeing and finishing, suede and leather, can be obtained with high strength, light quality, bright color, mouldproof and moth-proofing, flexibility is good wait for a characteristic, with its light, thin, soft, firm is famous for its advantages of combination, rain or shine in garment industry, and the price is low. [3]
(7) Other applications: Microfiber has been widely used in thermal insulation materials, filtration materials, ion exchange, artificial blood vessels, artificial skin and other medical materials, biological engineering and other fields. In nonwovens production, superfine fiber has been successfully used in the manufacture of synthetic leather base cloth and synthetic suede, but also used in melt-blown nonwovens, spunlace nonwovens, needle-punched nonwovens and other products. [3]
News report: The filter layer of the mask is mainly made of polypropylene melt-blown microfiber, which is very thin and cannot withstand high temperatures. When the temperature is higher than 80 degrees, it will shrink and deform, causing structural damage and reducing the protective effect. The entry of water will also make the charge in the filter layer disappear quickly, resulting in a significant decrease in the filtration effect
