1. Classification
There are many varieties of polyester filament, which can be divided by product, use, linear density, gloss, and twisting method. Commonly used is divided by product, the main products are as follows:
Undrawn yarn (UDY), its fiber molecules are basically not oriented; uncrystallized: this kind of yarn has low strength, long elongation, and poor dimensional stability, and generally cannot be directly applied. Semi-oriented yarn (MOY), the fiber molecules have been oriented in a small amount, and the degree of orientation is higher than that of UDY and lower than that of pre-oriented yarn; the structural state of this yarn is still not stable enough to be directly applied. Pre-oriented yarn (POY), which has been moderately stretched, has a certain degree of orientation, and has a small amount of microcrystalline particles, but it is still lower than the requirements of finished yarn: this kind of yarn has low strength and high elongation, and is generally still not suitable for processing fabrics directly . Highly oriented yarn (HOY) is produced by one-step ultra-high-speed spinning. The fiber has high molecular orientation and good dyeing performance, but the elongation and thermal shrinkage are large, which cannot meet the general wearing requirements. Drawn yarn (DY) is a yarn made by spinning and low-speed drawing, and its crystallinity is about 40%; this kind of yarn is straight, smooth, closely arranged with each other, and has poor fluffiness. Fully drawn yarn (FDY) is a yarn made by a one-step spinning and drawing method; this kind of yarn has stable quality, less wool, less end breakage, and good dyeing uniformity. It is an ideal yarn for high-speed weaving processing. Conventional textured yarn (TY) is a silk produced by a three-step process of spinning, winding, drawing, twisting, and false twisting, or by a high-speed spinning-low-speed false-twisting process; it has a certain Elasticity and bulkiness, good dimensional stability. Stretch textured yarn (DTY), generally using POY as raw material, is a low-elasticity yarn obtained by one-step stretching and deformation; it has a certain elasticity, and the hand feel is not as soft as TY, but the quality is stable, and the strength and elongation have met the requirements of taking. Air-textured yarn (ATY) has countless small filaments on the surface of the silk, which has the appearance of spun yarn, but does not have the aurora and waxy feeling of false-twist textured yarn, and its covering effect and thermal insulation are similar to worsted yarn. The new varieties of polyester filaments include differentiated fibers, functional fibers and artificial fibers. In recent years, with the development of artificial silk technology, polyester monofilament yarn has been developed towards fine fibrillation, and ultra-fine fibers with a linear density of 0.00011dtex have been produced. Second, performance 1 general performance of polyester fiber (1) strength. The fiber strength is high, generally 4.5~8cN/dtex, and the high-strength fiber is 5.6~8.OcN/dtex. Due to its poor hygroscopicity, the wet strength and dry strength are basically the same. (2) Moisture. The initial modulus of polyester is high. The civil filament is not less than 90cN/dtex, and the industrial yarn can reach 132 5cN/dtex. (3) Elasticity. The elasticity of the fiber is good, and its elastic recovery rate is 96% under 2% tension. The fabric does not wrinkle and has good dimensional stability. (4) Good heat resistance. The melting point of polyester is 255～260℃. When heated in air at 150℃ for 1000h, the color will change slightly, and the strength will not drop by more than 50%. (5) Shrinkage. Polyester fabrics shrink little or no. (6) Hygroscopicity. The hygroscopicity of polyester is poor, and the moisture regain is only 0.4%, because there are very few polar groups on polyester macromolecules. (7) PILLING. Polyester is easy to pilling and not easy to fall off. This is a fiber ball due to loose filaments and broken ends in the fabric. Because of the high fiber strength, fiber balls are retained on the fabric. The modified polyester with low tensile strength is not easy to pilling. (8) Dyeing. Because there are very few polar groups on polyester macromolecules, it cannot be dyed by general methods. With disperse dyes or non-ionic dyes, the dyeing effect is better. (9) Flammability. Polyester is more flammable than nylon, and the fibers melt and extinguish themselves when burned. (10) Chemical resistance. Its resistance to hydrolysis, antioxidant, acid and dry heat degradation are better than nylon, but not alkali. Taking advantage of this characteristic, polyester was modified by alkali reduction method. Characteristics of two polyester filaments Compared with polyester staple fibers, polyester filaments have the following characteristics: (1) Filament production is a single-spindle production method. A thread has dozens of monofilaments, and from spinning to deformation, it has to go through dozens of friction points, and it is easy to produce wool. In addition, filaments are produced by multiple spindles and multiple machines. Due to factors such as equipment, technology, operation, etc., filaments produced at different spindles will have certain differences in performance, and even the inner and outer layers of a bobbin will have differences in performance. difference. (2) Filament can imitate differentiated fibers by physical deformation. For example, by changing the shape of the spinneret or the strength of the twist, silk-type fibers can be spun; by methods such as false twisting, air texturing, blending, and compounding, the filaments can have a wooly style; by drawing and pre-orienting the filament The mixed fiber deformation of silk can make hemp slub silk; the mixed fiber deformation of filaments with different melting points or different degrees of orientation can make the filaments look like hemp; through various blowing techniques, it can be made into a network Silk, network textured yarn, air textured yarn, core-spun yarn, etc., can be made into looped yarn and wrinkled yarn by strong twisting method; ultrafine yarn can be spun by composite spinning and mechanical peeling method. (3) Filament can be imitated by chemical modification method as differential fiber. For example, through copolymerization, blending, grafting and other methods, the fiber has special properties such as easy dyeing, heat preservation, heat resistance, flame retardant, anti-fouling, anti-pilling, antistatic, high moisture absorption and high water absorption. 3. Purpose Polyester filament was mainly used for silk garments in the early days. With the development of various processing technologies, it has now been extended to the entire clothing field such as wool-like, linen-like, and cotton-like, and has been extended to the fields of decoration, industry and non-fiberization. develop. Clothing from underwear, shirts, jackets, suits to coats, ski shirts, etc.; decoration from headwear, scarves to curtains, tapestries, carpets, sofa covers, car seat covers, ponchos, tablecloths, umbrellas, etc.; bedding from sheets, quilts , pillow covers, quilt covers, bedspreads, mosquito nets, quilts, etc.; industrial sewing thread, cord, conveyor belt, filter cloth, rope, etc.; non-fiberized imitation leather products, films, bottles, etc.
