Basic Concepts of Chemical Fibres
Fiber is a long and thin substance with relative flexibility. The diameter of the typical textile fiber is from several microns to dozens of microns. The length is more than 25mm. The density is 10-5g/mm.
For textile fibers, there should be a larger elongation at break, which is between 10% and 50%.
2. Continuous Filament
During the chemical fiber production process, the fibers with a length of kilometers are called filaments, which include monofilament, multifilament, and cord thread. Monofilament is a continuous single fiber spun with a single hole spinneret. Multifilament is a filament composed of tens of monofilaments. Cord yarn is composed of more than one hundred to several hundred single fibers and is used to make the thread of tire cord fabric.
Tow is composed of tens of thousands to millions of monofilaments assembled into a bundle, which is used to cut into short fibers or to make slivers (top) after being stretched. The latter is also called stretch cut fiber (equivalent to cotton spinning Roving sliver).
Chemical fiber products are cut into lengths of several centimeters to ten centimeters, and fibers of this length are called short fibers. According to different cut lengths, short fibers can be divided into cotton, wool, and medium-length short fibers.
The length of cotton short fiber is 25～38mm. The fiber is relatively thin (line density is 1.3～1.7dtex). It is similar to cotton and mainly used for blending with cotton, which is called polyester-cotton fabric.
The wool-type short fiber has a length of 70-150mm and a thicker fiber (line density of 3.3-7.7dtex). It is similar to wool and is mainly used for blending with wool, which is called wool polyester fabric.
The length of medium-length short fibers is from 51mm to 76mm. The linear density of the fiber is between the cotton type and the wool type (2.2-3.3dtex). It is mainly used to make medium-length fiber fabrics.
5. Stretch Broken Tow
Short fibers of unequal length formed by longitudinal breakage of chemical fiber tows are also called unequal length short fibers.
6. Shaped Fibres
In the process of synthetic fibers production, we often use fibers with non-circular cross-sections or hollow fibers spun with special-shaped spinnerets (non-circular holes). Such fibers are called special-shaped cross-section fibers, or special-shaped fibers for short.
Shaped fibers have special luster, and have bulkiness, stain resistance, and pilling resistance. And fiber resilience and coverage can also be improved. For example, polyester with a triangular cross-section has glitter; five-lobed cross-section polyester has a luster similar to silk, anti-pilling, good hand feeling and coverage; some hollow fibers also have special uses, such as making reverse osmosis membranes for artificial use Kidney, seawater desalination, sewage treatment, hard water softening, etc.
7. Composite Fibres
The composite fiber is the melt or concentrated solution of two or more fiber-forming polymers. According to the difference in composition, proportion, viscosity, or variety, the polymers are respectively put into the same spinning assembly and placed in the appropriate part of the assembly. And then they converge and eject from the same spinning hole to form a single fiber, which is called a composite fiber.
There are many types of composite fibers, including side-by-side, skin-core, and dispersed (sea-island) types.
8. Textured Yarn
Textured yarn includes all yarns that have undergone texturing, such as stretch yarns and bulked yarns.
Stretch yarns are deformed filaments, which can be divided into high tapered yarns and low elastic yarns. The 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.
Bulk yarn uses the thermoplasticity of polymer to mix two synthetic fiber tops with different shrinkage properties in proportion. After heat treatment, the high-shrinkage tops force the low-shrinkage tops to curl, thereby making them stretchable and flexible.
Wool-like textured yarns and bulked yarns are mainly acrylics.
9. Superfine Fibre
Since the thickness of a single fiber has a great influence on the performance of the fabric, chemical fibers can also be classified according to the thickness (linear density) of the single fiber, and are generally divided into conventional fibers, fine fibers, ultra-fine fibers, and extreme-fine fibers.
The linear density of conventional fibers is 1.4-7dtex.
The fine denier fiber has a linear density of 0.55 to 1.3 dtex, which is mainly used for light-thin and medium-thick fabrics that simulate silk.
The ultra-fine fiber has a linear density of 0.11～0.55dtex, which is mainly used for high-density waterproof and breathable fabrics, artificial leather, and peach skin fabrics.
The ultra-fine fiber has a linear density below 0.11dtex, which can be produced by the sea-island spinning method, and is mainly used in special fields such as artificial leather and medical filter materials.
10. Differential Fibre
Generally speaking, differential fiber refers to the chemical fiber for consumption that has been innovated or given certain characteristics to conventional chemical fiber varieties through chemical modification or physical deformation.
Modifications in the polymerization and spinning process include copolymerization, super bright, super high shrinkage, hetero-staining, easy dyeing, fast dyeing, anti-static, anti-pilling, anti-mildew, anti-bacterial, anti-fouling, anti-odor, and moisture absorption, Sweat-absorbent, waterproof, fluorescent discoloration, and other fibers.
In the spinning, stretching, and texturing processes, there are blends, composites, hollows, special shapes, different shrinkage, different materials, different colors, fine deniers, ultra-fine, extra thick, three-dimensional crimps, networks, mixed fibers, and mixed entanglements, skin core, juxtaposition, slub, color mixing, coating, etc., which all belongs to the category of differentiated fibers.
Differentiated fibers are mainly used in clothing and apparel fabrics, which can improve economic efficiency, optimize processes, save energy, reduce pollution, and increase new textile products.
11. Special Fibre
Special fibers generally refer to chemical fibers with special physical and chemical structures, properties, and applications, such as high-performance fibers and functional fibers.
Special fibers are mainly used in industries and cutting-edge technology fields, etc.
Common Names and Codes of Chemical Fibers
The main varieties of chemical fiber generally have common names and codes, and their fiber-forming polymers usually have abbreviations. The names and codes of the main chemical fibers are shown in Table 1-2.
||sodium cellulose xanthate
||cellulose acetate fiber
Chemical fiber intermediate products and final products vary according to different spinning processes, and their names and codes are shown in Table 1-3.
||Low Oriented Yarn
||Polyester Pre-Oriented Yarn
||Fully Drawn Yarn
||Draw Textured Yarn
||Medium Oriented Yarn
||Fully Oriented Yarn
||Air Textured Yarn