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Solutions to Black Skin in Light-coloured Nylon Yarn and Fabrics

Views:561     Author:Site Editor     Publish Time: 2019-07-25      Origin:Site


Dyeing light-colored nylon yarns and fabrics often have black skin, which brings great losses to production. After several years of production practice, according to the characteristics of dyes and additives, a basic mature process has been explored, which has created a smooth production condition.



The Cause Of Black Skin


The dyeing tanks we use are mostly iron, and the iron is mostly composed of oxygen and water in the atmosphere to form a complex compound, namely rust. The composition of rust varies with the conditions at which it is formed. Nylon6 multifilament or fabrics are stained with rust during the dyeing process to form defects. Another point is that the water used in our industrial water is very hard, and the water contains a lot of calcium ions and magnesium ions. 


When these two ions encounter dyes or soaps, they will precipitate or agglomerate and accumulate in the yarn. A defect is formed on it. Both of these conditions can cause the fabric to yellow and, in severe cases, form a black skin on the surface of the yarn or fabric. This kind of black leather can not be washed with the general soap liquid, and the finished product is very unattractive. There are often a piece of yellow spots and black spots, especially when dyed in light colors such as red and golden.



Experimental Results


Regardless of the dye used to dye the brocade into red, golden, in order to get a better effect, you need to add oxalic acid and sodium pyrophosphate, both of which are indispensable.



Process


Through a large number of experiments, it is concluded that Nylon6 filaments (or fabric) is easy to produce black skin when dyeing some colors (such as red and golden), and its corresponding production process: dyeing→washing 2 times→drying→fixing 2 times→ Washed → soft → dried.


Among them, oxalic acid and sodium pyrophosphate are added in the first fixation. After the nylon yarn is treated with oxalic acid, the oxalic acid remaining on the fiber is thoroughly washed with water. If it is not washed, when the dry oxalic acid solution becomes concentrated, it will quickly damage the fiber and cause holes.



Process Formula

Acid dye: x%

Acetic acid: pH=3~4

Peregal: 2 - 1.6%

Stop tartar: 0.7~0.3%

Tannic acid: 1.2 to 1.0%

Sodium pyrophosphate: 0.48%

Oxalic acid: 0.5~0.3%



Conclusion

After several years of exploration and discussion, the production practice proves: When the nylon yarn or fabric is dyed in light color (such as red, golden), if there is stain or black skin, it can be treated with sodium pyrophosphate, and the treated yarn or fabric. The color is pure, this method is not only suitable for light colors, but also for medium and dark nylon yarn or fabric dyeing.


The mature process has greatly improved the quality of the fabric. Therefore, it is necessary to choose high-quality nylon yarn



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