1. What is Polyester Yarn?
Definition: Polyester yarn is a synthetic fiber yarn made of polyethylene terephthalate, also known as "polyester yarn" because of its chemical name. It is the world's largest and most widely used synthetic fiber.
Raw Material Source: Mainly derived from petrochemical products (terephthalic acid and ethylene glycol), which are polymerized into polyester chips or melts.
Essence: A tough, durable, stable and extremely versatile man-made textile material.

2. Core Characteristics and Advantages
Due to its chemical structure, polyester yarn has a series of excellent characteristics that make it stand out in many fields:
High strength and wear resistance: Polyester fibers are inherently strong, and the yarns made are very strong and durable, able to withstand large tension and repeated friction, and the fabric is not easy to break, pill or tear.
Excellent elasticity and wrinkle resistance: With good resilience, the fabric is not easy to wrinkle, easy to care for, dries quickly after washing and can maintain a good shape (good shape retention). Not easy to deform after wearing or using.
Good dimensional stability: Polyester yarn and its fabrics have very low shrinkage under normal use and washing conditions and are dimensional stable.
Quick drying: Poor hygroscopicity (hydrophobicity), moisture is not easily absorbed by the fiber, but quickly evaporates or is extracted on the surface, so the drying speed is much faster than natural fibers such as cotton, linen, and wool.
Chemical and light resistance: Good resistance to most acids, alkalis, oxidants, and organic solvents. Strong UV resistance, not easy to fade or degrade due to sunlight (better than most natural fibers and nylon).
High cost-effectiveness: Abundant raw materials, mature production technology, high efficiency of large-scale production, usually more cost-effective than other high-performance fibers (such as nylon, aramid) or natural fibers (such as high-quality cotton, silk, wool).
Easy care: The fabric is easy to wash, dries quickly, and usually does not need ironing.
Strong plasticity: Its gloss, feel (from rough to silky), cross-sectional shape (round and special-shaped cross-sections increase moisture absorption and moisture conductivity), and functionality (such as antibacterial, flame retardant, UV resistance, moisture absorption and perspiration, etc.) can be adjusted through spinning process, finishing technology (such as alkali reduction treatment to increase softness and drape), modification (such as adding masterbatch), etc.

3. Main production process flow
The production of polyester yarn is mainly divided into two major routes:
Chip spinning:
Polymerization: Polymerize terephthalic acid (PTA) and ethylene glycol (MEG) into polyester melt.
Pelletizing: Cool and pelletize the melt to make polyester chips.
Drying: The chips need to be fully dried to remove moisture (moisture will cause hydrolysis and degradation at high temperature).
Melt spinning: The dried chips are heated and melted in a screw extruder.
Spinning: The melt is accurately metered by a metering pump and extruded into a thin stream through the micropores of the spinneret.
Cooling and solidification: The fine stream is cooled and solidified in the air or in a special cooling device to form nascent fibers (undrawn yarns, such as UDY and POY).
Post-processing: Including:
Drawing: The nascent fibers are hot-drawn (once or more) to greatly increase the orientation and crystallinity of the fibers, thereby significantly increasing the strength and reducing the elongation. Fully drawn yarn (FDY) is obtained.
Deformation processing: It is mainly performed on pre-oriented yarns (POY). Common methods include false twist deformation (producing stretch yarn DTY - Draw Textured Yarn) and air deformation (producing air-deformed yarn ATY - Air Textured Yarn), which give the yarn curl, bulk and elasticity.
Cutting (short fibers): The filament bundles are cut into short fibers of the desired length (usually several centimeters).
Staple spinning: The polyester staple fibers are subjected to traditional spinning processes such as opening, carding, drawing, roving, and spun yarn to make polyester staple yarns (ring spinning, air spinning, vortex spinning, etc.).
Melt direct spinning:
Polymerization: Same as above.
Direct spinning: The polyester melt obtained by polymerization does not go through the pelletizing and remelting steps, but is directly transported to the spinning box for metering, spinning, cooling and solidification.
Post-processing: Same as slice spinning, producing FDY, POY, etc. Melt direct spinning eliminates the pelletizing, drying and remelting steps, with higher efficiency, lower energy consumption and more cost advantages, but it has extremely high requirements for production continuity and stability.

4. Main types of polyester yarns
According to the morphology and processing methods, polyester yarns are mainly divided into two categories:
Polyester filament yarn (Filament Yarn):
Undrawn yarn (UDY): Low strength, high elongation, unstable; mainly used as the raw material of POY, not directly used for weaving.
Pre-oriented yarn (POY - Partially Oriented Yarn): It has a certain degree of orientation and better stability than UDY. It is the most important intermediate raw material for the production of textured yarn (DTY) and drawn yarn (FDY).
Fully drawn yarn (FDY - Fully Drawn Yarn): After full stretching, the structure is stable, the strength is high, the elongation is low, and the hand feel is hard. The surface is smooth and the gloss is good (glossy, semi-dull, full-dull). It is widely used in weaving and knitting to produce imitation silk, lining, shirt fabrics, mosquito nets, sewing threads, etc.
Drawn textured yarn (DTY - Drawn Textured Yarn): It is made from POY through false twisting and deformation. It has permanent curling, fluffy, good elasticity (low elasticity, medium elasticity, high elasticity), soft hand feel, good coverage, and better moisture absorption and breathability (through capillary action) than FDY. It has a wide range of applications, such as knitted underwear, T-shirts, sportswear, socks, sweaters, home textile fabrics (curtains, sofa fabrics), blankets, filling cotton, etc.
Air Textured Yarn (ATY): High-pressure air is used to impact the filament bundle, so that the single filaments are separated, bent, and entangled to form irregular loops and hairiness. The appearance is close to that of staple yarn, and it has the characteristics of being fluffy, wooly, good covering, and low gloss. It is used for imitation wool fabrics, decorative fabrics, furniture fabrics, automotive interiors, shoe materials, etc.
Polyester Staple Yarn (Spun Yarn/Staple Fiber Yarn): Polyester filament bundles are cut into short fibers (usually 32mm, 38mm, 51mm in length, etc.), and then spun into yarns through traditional spinning systems such as** ring spinning, air spinning (OE), vortex spinning (Vortex)**, just like cotton or wool.
Features: The appearance and feel are closer to natural fiber yarn (such as cotton yarn), with hairiness, good fluffiness, and moisture absorption and air permeability are usually better than filament yarns of the same specifications (because the yarn structure is looser).
Application: Widely used in pure polyester fabrics (such as polyester cloth, filling cotton) or blended with other fibers such as cotton, linen, viscose, wool, etc. (such as T/C 65/35, T/R, T/W, etc.). Used to make shirts, pants, jackets, work clothes, sheets, quilt covers, towels, blankets, etc.
Yarn count: Usually Ne or Tex is used to indicate the thickness (such as 40s/1, 32s/1, 20s Ne; 30T, 50T Tex).

5. Main application areas
The application of polyester yarn has penetrated almost all textile-related fields:
Clothing:
Outerwear: shirts, pants, skirts, jackets, suits, down jacket fabrics (anti-drilling down), windbreakers (often blended with cotton).
Underwear and sportswear: T-shirts, sweatshirts, yoga pants, quick-drying clothes, swimsuits (elastic DTY, high color fastness). Functional polyester (moisture wicking, antibacterial, cool feeling) is prominently used in this field.
Socks: DTY elastic yarn is the main raw material.
Sweaters: Polyester wool-like yarn or cashmere-like yarn.
Home textiles:
Bedding: sheets, quilt covers, pillowcases (pure polyester or blended).
Curtain and sofa fabrics: DTY, FDY, ATY, requiring good color fastness, UV resistance, wear resistance, flame retardancy (special finishing).
Blankets and towels: Polyester Raschel blankets, bath towels, floor mats (spun yarn or ATY).
Filling: Polyester hollow fiber filling cotton is used for pillows, quilts, sofa cushions, dolls.
Industrial textiles:
Tire cord: High-strength polyester industrial yarn is an important choice for radial tire skeleton materials (second only to steel cord).
Conveyor belts, canvas, ropes, safety belts: take advantage of its high strength, wear resistance, and weather resistance.
Geotextiles and geogrids: used in civil engineering (highways, railways, water conservancy), requiring corrosion resistance and high strength.
Filter materials: used for air filtration (dust bags) and liquid filtration.
Tarpaulin: waterproof and UV-resistant coating.
Sewing thread: high-strength polyester filament and staple fibers are widely used.
Nonwoven fabrics: Polyester staple fibers are important raw materials for the production of spunbond, needle-punched, spunlace, hot air cotton, etc., and are used in sanitary materials (sanitary napkins, diaper surface/drainage layer), medical supplies, wipes, filter materials, agricultural coverings, shopping bags, etc.

6. How to choose polyester yarn? Considerations
Choosing the right polyester yarn depends on the needs of the final product and the processing technology:
End use: Is it clothing (what type?), home textiles (curtains? Bedding?), industrial use (specific functions?)? The use determines the required core performance (strength, elasticity, feel, appearance, functionality).
Processing method: Is it weaving (tatting) or knitting? High-speed looms require higher yarn strength and uniformity; knitting usually requires a certain degree of elasticity and softness (commonly used for DTY).
Required characteristics:
High strength and wear resistance requirements? FDY, high-strength industrial yarn or staple yarn.
Need elasticity and fluffiness? DTY.
Pursuing wool-like or plush feeling? ATY or staple yarn (coarse count).
Require smooth and bright appearance? FDY (glossy).
Need moisture absorption and perspiration? Choose polyester yarn with a special cross-section (cross, W-shaped, etc.) or hydrophilic finishing (such as Coolmax® raw material).
Need flame retardancy? Choose additive or copolymer flame retardant polyester yarn.
Need antibacterial? Choose polyester yarn with antibacterial agent added.
Yarn specifications:
Filament: Indicated by fineness (Denier/D or dtex) and number of filaments (F). For example: 75D/72F means the total fineness is 75 denier, consisting of 72 monofilaments. The larger the D number, the thicker the yarn, and the larger the F number, the softer and finer the yarn.
Staple yarn: Indicated by yarn count (Ne or Tex) and number of strands. For example: 40s/1 (40 Ne single yarn), 32s/2 (32 Ne double strand yarn). The larger the count, the finer the yarn (Ne), and the larger the Tex, the thicker the yarn (Tex).
Gloss: glossy, semi-dull, full-dull. Choose according to the product appearance requirements.
Virgin yarn vs. recycled yarn: Recycled polyester yarn (made from recycled plastic bottles or textile waste) has advantages in sustainability, and its performance is close to that of virgin yarn, which is an important development direction at present.
Cost budget: The prices of yarns of different specifications, functionality and quality vary greatly. Melt direct spinning FDY is usually cheaper; special functional yarns and ultra-fine denier yarns are more expensive.

7. Market Trends and Development
Sustainability: The demand and production capacity of recycled polyester (rPET) continue to grow rapidly, promoting the circular economy. Bio-based polyester (part of the raw materials come from biomass) is also being explored. Energy-saving and emission-reducing production processes are valued.
Functionalization and differentiation:
Polyester yarns with functions such as moisture absorption and perspiration, quick drying, cool feeling, warmth retention (far-infrared heating), antibacterial and deodorizing, and UV resistance.
Microfiber, special-shaped cross-section yarns (improving comfort and appearance).
The performance of elastic polyester yarns continues to improve (higher elasticity and longer durability).
Special polyester yarns for industrial use such as flame retardant, anti-drip, and antistatic.
Blended and composite: Blended yarns or core-spun yarns (such as polyester-spun spandex) of polyester and other fibers (cotton, linen, viscose, Tencel, modal, wool, nylon, spandex) to combine the advantages of different fibers.
Intelligent manufacturing: The level of automation, digitization, and intelligence of the spinning process continues to improve.