Polyester fiber is one of the most widely used synthetic fibers in the global textile industry. Due to its high strength, abrasion resistance, easy dyeing, and wrinkle resistance, it is widely used in clothing, home textiles, industrial fabrics, and other fields. Fiber grade polyester chips are the key raw material for polyester fiber production.
How to Choose the Proper Polyester Chips
Classification and Applications of Textile-Grade Polyester Chips
Classification by Glossiness
The glossiness of polyester chips is primarily adjusted by adding matting agents (such as titanium dioxide TiO₂).
>>> Super Bright PET Chips
Main Characteristics:
No matting agents are added, resulting in high transparency and a brilliant gloss.
The fiber surface is smooth and highly reflective, with a silk-like luster.
Applications:
It is suitable for textiles requiring high gloss.
Silk-like fabrics: such as chiffon, georgette, and other high-end women’s clothing fabrics.
Bright yarn: used in embroidery thread, decorative ribbons, etc.
Highly transparent industrial yarn: such as high-strength transparent sewing thread.
>>> Semi-Dull PET
Key Features:
A small amount of TiO₂(approximately 0.3%-0.5%) is added, resulting in a moderate gloss.
The fiber surface has a slightly soft feel, similar to the appearance of natural fibers.
Applications:
Conventional polyester yarn. Used for woven and knitted fabrics (such as shirts, T-shirts, and sportswear).
Blended yarn. Blended with cotton, viscose, and other fibers to improve wrinkle resistance and abrasion resistance.
Home textile products. Such as bed sheets, curtains, and sofa fabrics.
>>> Full-Dull PET
Key Features:
High TiO2 content (approximately 1%-2.5%) creates a matte finish.
The fiber has strong light absorption, visually closer to the texture of natural cotton and linen.
Some products also undergo a chemical matte treatment to further reduce the gloss.
Applications:
Cotton-like and linen-like fabrics. Used in casual wear, home wear, and other homewear. High-end sportswear. Reduce glare and enhance comfort.
Specialty workwear fabrics. For products requiring low visibility, such as military uniforms and outdoor gear.
Classification by Viscosity
The intrinsic viscosity (IV) of polyester chips directly affects the fiber’s strength, spinnability, and end-use application.
>>> Low-viscosity chips (IV 0.50-0.65 dl/g)
Properties:
Low molecular weight, good melt flowability, suitable for high-speed spinning.
Moderate fiber strength and high elongation.
Applications:
Conventional polyester staple fiber. Used for filling cotton and nonwovens.
Pre-oriented yarn POY. Used for subsequent texturing to produce draw-textured yarn DTY.
>>> Medium-viscosity chips (IV 0.65-0.80 dl/g)
Properties: Balances spinnability and fiber strength, making it the most widely used.
Applications:
Suitable for conventional spinning and some industrial yarn production.
Fully Drawn Yarn FDY. Used for woven and knitted fabrics.
Common industrial yarn. Such as conveyor belts and tarpaulins.
>>> High-viscosity chips (IV 0.80-1.00+ dl/g)
Characteristics:
High molecular weight, high melt strength, and fibers with ultra-high strength and low elongation.
Requires special spinning equipment, such as high-pressure spinning.
Applications:
High-strength industrial yarn: Such as tire cord, seat belts, and bulletproof materials.
Ultrafine denier fiber: Used in high-end filter materials and medical textiles.
Polyester Fiber Production Process
Polyester fiber production primarily involves melt spinning, drawing, winding, and post-processing.
>>> Polyester Chip Drying
Because polyester chips are hygroscopic, moisture can cause hydrolysis when melted at high temperatures, affecting fiber quality. Therefore, pre-crystallization and drying are necessary.
Pre-crystallization. Crystallize the chips at 120-140°C to prevent sticking.
Drying. Use hot air or vacuum drying to reduce the moisture content of the chips to below 0.005%.
>>> Melt Extrusion
The dried yarn grade polyester chips enter a screw extruder and are heated to 270-290℃ to melt. A metering pump precisely controls the melt flow rate to ensure spinning stability.
>>> Melt Spinning
The molten polyester melt is extruded through a spinneret, forming a thin stream. It cools and solidifies in air to form nascent fibers.
Number of spinneret holes. This determines the fiber specifications (such as, monofilament, multifilament).
Cooling method: Side air or ring air affects fiber uniformity.
>>> Stretching and Heat Setting
Synthetic fibers have low strength and high elongation, so stretching is required to improve orientation and crystallinity and enhance mechanical properties.
Pre-stretching. Initial stretching is performed at a glass transition temperature of approximately 70-80℃.
Hot-stretching. Further stretching (usually 3-5 times) is performed on heated rollers or a hot box to achieve more regular molecular chain alignment.
Heat Setting. A relaxation heat treatment at high temperatures (180-220℃) eliminates internal stress and improves dimensional stability.
>>> Winding and Post-Processing
The stretched fibers are then wound and formed, and then subjected to various post-processing steps depending on the intended use.
Texturing: For example, false twisting is used to produce stretch yarn.
Staple Fiber Production: Polyester staple fibers are cut and baled to form them.
Industrial Yarn Production: High-strength, low-elongation yarns are used for tire cord, conveyor belts, and other applications.
What are the Advantages of Polyester Fiber?
- High Strength and Abrasion Resistance
High breaking strength. Polyester has a strength of approximately 4.5-7.5 g/d (compared to 2.5-4.5 g/d for cotton), making it suitable for durable textiles.
Excellent abrasion resistance. It resists pilling and tearing even after repeated friction, making it widely used in high-use products such as jeans, backpacks, and sneakers.
- Elasticity and Wrinkle Resistance
High elastic recovery. After stretching 5%-6%, it fully recovers, retaining its shape and shape, making it suitable for tights and sportswear.
Strong wrinkle resistance. Its molecular chain is highly rigid, allowing it to remain flat after washing without ironing.
- Dimensional Stability
Low moisture absorption. It is resistant to shrinkage and can be blended with cotton to improve shrinkage.
Good heat resistance. With a softening point of 230-240℃ and a melting point of 255-265℃, it is suitable for high-temperature setting processes.
- Chemical Resistance
Acid and weak alkali resistant. Suitable for industrial filter cloths and protective clothing.
Bleach-resistant. Suitable for frequent washing, suitable for hospital bed sheets, hotel textiles, and more.
- Light and Weather Resistance
Superior UV stability compared to nylon and cotton, making it less susceptible to aging when used outdoors. Yarn grade PET chips is suitable for awnings and automotive textiles.
Adding UV-blocking additives can further enhance sun protection.
- Mildew and Insect Resistant
High hydrophobicity inhibits mold growth, making it suitable for humid environments such as bathroom curtains and outdoor furniture.
- Easy Dyeing and High Color Fastness
Dyeing with disperse dyes produces vibrant colors with the highest standards of wash fastness.
Cationically dyeable modified polyester achieves deep, highly saturated colors.
- Easy to wash and dry
Water evaporates 2-3 times faster than cotton, making it suitable for quick-drying clothing, swimwear, and sportswear.
Stains are less resistant to penetration and easier to remove.
- Lightweight and comfortable
With a lower density than cotton, it can be used to make lightweight clothing, such as down jackets.
Ultrafine polyester can simulate the feel of silk.