Classification and introduction of synthetic fibers

Synthetic fiber is a chemical fiber made by spinning a synthetic linear polymer with a suitable molecular weight and having solubility (or meltability) through spinning and post-processing. Compared with natural fibers and man-made fibers, synthetic fiber production is not restricted by natural conditions. In addition to the general superior properties of chemical fibers, such as high strength, light weight, easy washing and quick drying, good elasticity, and not afraid of mold worms, synthetic fibers each have certain unique properties.


Filament


In the manufacturing process of synthetic fibers, after the spinning fluid (melt or solution) is subjected to spinning forming and post-processing procedures, the resulting fiber with a length of kilometers is called filament. Filament includes monofilament, multifilament and cord yarn.


01

Monofilament


Originally referred to as a continuous single fiber spun with a single-hole spinneret, but in practical applications often also includes a few-hole filament composed of 3 to 6 single fibers spun from a 3 to 6-hole spinneret. The thicker synthetic fiber monofilaments (with a diameter of 0.08-2mm) are called bristles and are used to make ropes, brushes, daily net bags, fishing nets, or industrial filter cloths; the thinner polyamide monofilaments are used to make Transparent female socks or other high-grade knitwear.


02

Multifilament


A thread composed of dozens of single fibers. The multifilament of chemical fiber is generally composed of 8 to 100 single fibers. The majority of consumer fabrics are woven with multifilaments, because multifilaments composed of multiple single fibers are more flexible than single filaments of the same diameter.


03

Cord


A wire composed of more than one hundred to several hundred single fibers used to make tire cord fabric, commonly known as cord yarn.


short fibre


Chemical fiber products are cut into lengths of a few centimeters to a dozen centimeters, and fibers of this length are called short fibers. According to different cutting lengths, short fibers can be divided into cotton-type short fibers, wool-type short fibers, and medium-length short fibers.


01

Cotton staple fiber


The length is 25-38mm, the fiber is thin (linear density is 1.3-1.7dtex), similar to cotton fiber, mainly used for blending with cotton fiber, such as cotton polyester short fiber and cotton fiber blending, the resulting fabric Called "polyester cotton" fabric.

02

Wool staple fiber


The length is 70 ~ 150mm, the fiber is thicker (linear density 3.3 ~ 7.7dtex), similar to wool, mainly used for blending with wool, such as wool polyester short fiber and wool blending, the resulting fabric is called "wool polyester "Fabric.


03

Medium long fiber


The length is 51-76mm, and the thickness of the fiber is between the cotton type and the wool type (the linear density is 2.2-3.3dtex), which is mainly used for weaving medium-length fiber fabrics. In addition to being blended with natural fibers, staple fibers can also be blended with other staple fibers of short fibers. The resulting blended fabrics have good comprehensive properties.


In addition, short fibers can also be purely spun. In the current production of chemical fibers worldwide, the output of short fibers is higher than that of filaments. According to the characteristics of fibers, some varieties (such as nylon) mainly produce filaments; some varieties (such as acrylic) mainly produce short fibers; and some varieties (such as polyester) have a similar ratio.


Coarse detail


Coarse detail silk is abbreviated as T & T silk. From its shape, you can see alternating thick and thin sections, and after dyeing the silk strip, you can see the alternating shades of light and dark. The coarse-grained yarn is manufactured by the uneven drafting technique after spinning. The difference in the properties of the two parts of the yarn produced can be controlled in production. Its distribution is irregular and in a natural state.

Coarse detail yarns have low strength, thick elongation at break, strong heat shrinkage, good dyeability, and easy alkali reduction processing. These characteristics can be used to develop textiles with unique properties. The physical properties of coarse-grained yarn are related to factors such as the diameter ratio of coarse-grained yarn.

The general coarse-grained yarn has higher elongation at break and shrinkage in boiling water and lower breaking strength and yield. Its strong shrinkage properties can make thick-grained yarns mixed with other yarns to become hetero-shrinked blended yarns. In addition, problems such as the easy deformation and low strength of coarse knuckles of coarse details should be paid attention to during weaving, dyeing and finishing.

The original coarse-grained yarns were round yarns. With the development of coarse-grained yarn production technology, some special coarse-grained yarns have appeared one after another, such as special-shaped coarse-grained yarns, mixed thick and thin yarns, microporous coarse-grained yarns, and fine denierized coarse-grained yarn Details such as silk, they have a special feel and style, or have a special absorption, and are mostly used to develop high-end fabrics.


Textured yarn


Deformed yarns include all textured yarns and yarns, such as stretch yarns and bulked yarns.


01

Stretch silk


The deformed filament can be divided into two types: high-elasticity and low-elasticity. Elastic yarn has good stretchability and bulkiness, and its fabric is close to wool, silk or cotton in terms of thickness, weight, opacity, coverage and appearance characteristics.


Polyester stretch yarn is mostly used for clothing, nylon stretch yarn is suitable for production of socks, and polypropylene stretch yarn is mostly used for household fabrics and carpets. Its deformation methods mainly include false twist method, air jet method, hot air jet method, stuffing box method and shaping method.


02

Bulked yarn


That is, using the thermoplasticity of the polymer compound, two synthetic fiber tops with different shrinkage properties are mixed in proportion.After heat treatment, the high shrinkage tops force the low shrinkage tops to curl, making the mixed tops elastic and fluffy, which becomes similar The textured yarn of yarn. At present, the output of acrylic bulked yarn is the largest, and it is used for making knitted outerwear, underwear, wool, blankets, etc.


Differentiated fiber


The foreign word of differentiated fiber system, which originated in Japan, generally refers to the fiber material obtained by physical deformation or chemical modification on the basis of the original chemical fiber. It is obviously different from the ordinary chemical fiber in appearance and intrinsic quality. Differentiated fiber improves and enhances the performance and style of chemical fiber, but also gives chemical fiber new functions and characteristics, such as high water absorption, electrical conductivity, high shrinkage and dyeability.


Differential fibers are mainly used to improve the simulation effect, improve comfort and protection, so they are mainly used to develop artificial textiles that imitate wool, linen, and silk, and some are also used to develop decorative textiles and industrial textiles.


Shaped fiber


In the spinning process of synthetic fibers, fibers with a non-circular cross-section or hollow fibers spun with special-shaped spinning holes are called special-shaped cross-section fibers, which are called special-shaped fibers for short. At present, there are dozens of types of profiled fibers. About 50% of the polyester fibers, polyamide fibers and polyacrylonitrile fibers sold on the market are profiled fibers.

Gloss and feel


The gloss of the fiber is related to the cross-sectional shape of the fiber. Triangular cross-section wire and trilobal cross-section wire have shining luster, which improves the "aurora" phenomenon of circular fibers. For example, a triangular cross-section polyester fiber or polyamide fiber blended with other fibers has a glittering effect, and is suitable for the development of silk-like fabrics, wool-like fabrics and various velvet fabrics. Flat, ribbon-shaped, dumbbell-shaped cross-section synthetic fibers have the feel and luster of fibers such as hemp, antelope wool and rabbit hair.


Polyester filaments with a five-leaf cross-section have a silk-like luster, and are also resistant to pilling, feel and coverage. Polygonal cross-section yarns have a flashing effect, strong covering power, and soft touch. They are mostly used to make textured yarns for knitted fabrics and socks, and their short fibers are used for blending to make a variety of wool-like fabrics and blankets. Rectangular cross-section silk has a soft luster, close to the luster of silk and animal hair. The blend of short fiber and cotton fiber has a wool style, and blending with wool can get a unique and shiny fabric.


02

Mechanical properties, water absorption and dyeability


Special-shaped fibers have higher rigidity, resilience and coverage can also be improved, and the strength is slightly reduced. In addition, the special-shaped fiber has a large surface area, enhanced transmission of water and steam, and fast drying speed and good dyeability.


03

Pilling resistance, bulkiness and breathability


Fibers with a flat cross-sectional shape can significantly improve the fuzzing and pilling phenomenon, and the greater the flatness, the better the effect. For example, after polyester and polyamide flat-section fibers are blended with wool, the fabric is generally not easy to pilling. Profiled fibers usually have good fluffiness, full-feeled fabric, strong warmth, and because of the increase in porosity, the air permeability is good. As the irregularity of the cross section increases, its fluffiness and air permeability also improve.


04

Hollow fiber specificity


Hollow fibers are excellent in heat retention and bulkiness. Some hollow fibers also have special uses, such as making reverse osmosis membranes for artificial kidneys, seawater desalination, sewage treatment, hard water softening, and solution concentration.


Composite fiber


There are two or more immiscible polymers in the fiber cross section. This chemical fiber is called composite fiber, or bicomponent fiber. Because the two or more components contained in this fiber complement each other, the performance of composite fibers is usually superior to conventional synthetic fibers and has many uses.

There are many varieties of composite fibers, which can be divided into two categories according to their shape, namely double-layer type and multi-layer type. The double-layer type includes side-by-side type and skin-core type, and the multi-layer type includes side-by-side multi-layer type, radial type, multi-core type, wood grain type, embedded type, island type and split type, etc.