Highsun Synthetic Fiber Technologies Co., Ltd

How to Improve the Dyeing Uniformity of Nylon 6 FDY Fine Denier Spinning?

Nylon 6 fdy fine denier yarn with single fiber size less than 1.1d has soft and delicate hand feeling, smoothness and fullness, good air permeability and high elasticity. It is an ideal raw material for garment fabric processing. However, the uneven dyeing caused by tensile deformation in one-step spinning is easy to be encountered. How can we prevent this problem? We may as well listen to Highsun's suggestions.

The dyestuff molecules must penetrate into the amorphous region of nylon 6 fdy fine denier yarn to dye whether it is masterbatch spinning or late dip dyeing. The fluctuation of amino group content in molecular chain and the difference in the structure of fiber in different packages or in the same package caused by tensile deformation are easy to cause color difference. 

The distribution of spinning finish on the fiber surface is not uniform, and the color difference is easy to occur in the later stage of dip dyeing. It is advantageous to improve the permeability, lubricity and high temperature resistance of the oil. In addition, with the same oiling rate and lower oil concentration, fine denier pa6fdy fiber is more easily saturated with water absorption, which is conducive to eliminating the uneven dyeing caused by the difference of water content between inside and outside the fiber. 

At the same time, the lower machine package cylinder is more balanced, which is more conducive to eliminating the influence of the external humidity environment on the fiber, reducing the fiber difference between different packages, and reducing the "deep" and "light" color difference caused by late dip dyeing. On this basis, the optimization of spinning process is an effective way to improve dyeing evenness. 

Fine denier nylon fdy yarn for civil use has the characteristics of fine denier, large specific surface area, fast heat dissipation, poor tensile strength, easy orientation, crystallization, etc. The structural difference between single fiber is larger than that of coarse denier industrial filament. Higher fluidity is required for spinning chips. Spinning temperature is slightly higher than that of conventional spinning, and lower air blowing speed and spinneret drawing ratio are favorable to improve dyeing uniformity. 

However, the effect of eliminating dyeing unevenness is more obvious by using Highsun in-situ polymerized nylon 6-color chips. In situ polymerized nylon 6-color chips are black from polymerization, unlike masterbatch spinning, which requires additional mixing equipment and manual operation, thus eliminating a dangerous point. 

In-situ polymerized polyamide 6-color chip spinning made by the nylon yarn supplier does not have late dip dyeing and finishing, so there is no dyeing unevenness caused by complicated process control such as dip dyeing temperature, dye leveling agent and dye concentration. In production control, the safety of improving dyeing uniformity is higher. 

In-situ polymerized nylon 6-color chip spinning is not easy to be broken. The service life of the module can reach more than 45-60 days, far more than that of masterbatch spinning. High spinnability is the fundamental method to improve dyeing uniformity. More importantly, the in-situ polymerized nylon chip colorants participate in the polymerization production, and the distribution of the colorants in the nylon 6 molecular chain is more uniform, and the dyeing uniformity of the spun fine denier filament is far better than the master batch spinning energy ratio.

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