Different Functions of POY and DTY Finishing Oils

Polyester POY (Partially Oriented Yarn): A semi-finished yarn produced directly by high-speed spinning. It features a moderate molecular orientation of fibers and cannot be used for direct weaving. Primarily serving as the raw material for finished yarns such as DTY, it requires post-processing at high temperature and high speed including texturing and drawing.

Polyester DTY (Draw Textured Yarn): An elastic yarn processed from POY via false texturing machines. It is categorized into low-elastic yarn, medium-elastic yarn and other types. Applicable directly to knitting and weaving, it serves as a core raw material for fabric production.

Their processing techniques and application scenarios differ drastically, which also results in entirely different performance focuses, ingredient ratios and functional objectives for the matching finishing oils.

一、Polyester POY Finishing Oil: Optimized for High-speed Spinning and Compatible with Texturing Processing

Polyester POY finishing oil is specially used in the spinning process and applied during high-speed spinning. Its core purpose is to ensure proper formation of POY and smooth subsequent texturing. Its main functions are as follows:

1、High-speed lubrication to reduce yarn fuzz and breakage.

The spinning speed of POY exceeds 3000 meters per minute. The running yarns undergo frequent friction with yarn guides and spinning assemblies at such high speeds.

The lubricating components in POY finishing oil, such as polyethers and fatty acid esters, form a uniform thin oil film on the fiber surface. This reduces the friction coefficient between yarn and metal as well as between yarns, preventing fuzzing and breakage at high running speeds. It ensures continuous spinning and minimizes waste yarn.

2、Excellent antistatic performance to prevent yarn tangling.

Polyester fiber is inherently an insulator. Static electricity readily generates from high-speed friction, which causes yarn loosening, adhesion and poor winding formation.

The antistatic ingredients in POY finishing oil improve the surface hygroscopicity of fibers, quickly dissipate static electricity and neutralize electric charges. This keeps yarns well bundled, delivers neatly wound POY bobbins with uniform unwinding tension, and lays a solid foundation for subsequent texturing.

3、High temperature resistance, suitable for high-temperature texturing processes.

POY undergoes high-temperature false twisting and drawing in subsequent processes, with processing temperatures generally ranging from 180 to 220°C. This requires POY finishing oil to have excellent heat resistance.

High-quality POY finishing oil resists volatilization and decomposition at high temperatures, and will not produce excessive tar or white powder to contaminate equipment. Meanwhile, it maintains the integrity of the oil film, preventing tension fluctuation and yarn breakage caused by oil failure during texturing.

4、Compatible with post-processing, balancing bundling performance and permeability.

POY finishing oil needs to balance bundling property and permeability. Good bundling keeps yarns neat for subsequent processing. Its permeability ensures the oil adheres evenly to every filament without uneven oil pick-up, and ultimately delivers uniform dyeing during DTY production.

Tip: The oil content of POY is generally controlled between 0.25% and 0.5%. Too little oil tends to cause static electricity and yarn breakage, while excessive oil will lead to slippage and unstable tension during texturing.

二、Polyester DTY Finishing Oil: Optimize Finished Yarn Performance and Adapt to End Weaving Processes

Polyester DTY finishing oil is exclusively for finished yarns and applied in the later stage of false texturing. Its core goal is to improve the quality of finished DTY yarn and adapt to end weaving processes such as knitting and weaving. Its functions differ markedly from those of POY finishing oil.

1、Friction adjustment to meet weaving requirements.

DTY is directly used on weaving machines, which calls for precise control over yarn friction properties. Mineral oil and lubricating components in the finishing oil reduce friction between yarns and knitting needles/heald wires, minimizing yarn breakage and fuzzing during weaving. Meanwhile, they moderately increase inter-yarn friction to maintain good bundling, preventing unclear shed and yarn skipping in weaving.

2、Long-term anti-static, smooth weaving guaranteed.

High-speed weaving easily generates static, leading to fabric streaks and color difference. DTY oil features excellent room-temperature antistatic performance, long-term static resistance and uniform yarn arrangement, improving production yield.

3、Enhance hand feel and luster, upgrade fabric texture.

DTY finishing oil endows fibers with a soft and smooth handle, and modulates surface luster to eliminate harsh glare. The finished fabric features a mellow touch and gentle sheen. It also improves fiber cohesion, delivering fuller bulkiness and better elasticity to the fabric.

4、Improve dyeing uniformity and reduce defects.

Even adhesion of the oil agent unifies the hydrophilicity and hydrophobicity of fiber surfaces. This enables uniform dye absorption in subsequent printing and dyeing processes, effectively preventing dye mottling, color difference, oil stains and other dyeing defects, and upgrading the overall dyeing quality of fabrics.

Tip: The oil content of DTY is adjusted according to application. It is about 2%–3% for knitting yarn and 0.5%–1.5% for weaving yarn, much higher than that of POY.

三、 Conclusion

Though oil agent accounts for only a tiny proportion of polyester filament, it is a key factor governing production efficiency, product qualification rate and fabric quality. POY oil agent features high temperature resistance and stable processing performance, while DTY oil agent focuses on superior hand feel and weaving adaptability. The two differ greatly in formula, performance and oil application standards, and shall never be used interchangeably.

For chemical fiber manufacturers, selecting suitable oil agents and precisely controlling oil content can cut down production failures and costs, and strengthen the competitiveness of filament products. For textile downstream processors, a good understanding of oil agent properties helps better control raw material quality and reduce weaving troubles.

Small as fiber oil agent is, it embodies profound expertise in chemical fiber production. These invisible details underpin the quality baseline of high-grade polyester filament.