Why is the yarn brittle after dyeing with Sulphur Black dye? How can I prevent it? What should we pay attention to in the process?

Why is the spinning thread brittle after Sulphur Black Br dye coloring? How can I prevent it? What should we pay attention to in the process?

A sulfide black dye is a high molecular compound containing more sulfur, its structure contains disulfide bonds and polysulfide bonds, and it is very unstable. In particular, the polysulfide bond can be oxidized to sulfur oxide by oxygen in the air under certain temperature and humidity conditions, and further interact with water molecules in the air to generate sulfuric acid, thus reducing the strength of the spinning yarn, fiber brittleness, and all fibers are embrittle into powder when severe.

 For this reason, in order to reduce or prevent fiber brittleness damage after spinning yarn with Sulphur Black Br dye, the following points must be paid attention to: ① The amount of Sulphur Black Br dye should be limited, and the amount of silk special color dye should not exceed 700g/package. Because the amount of dye is high, the chance of brittleness is large, and the fastness of dyeing is reduced, and washing is more difficult. ② After the color should be fully washed, do not wash clean, the floating color on the spinning yarn line is easy to decompose into sulfuric acid in the storage process and make the fiber brittle. ③ After coloring, urea, soda ash and sodium acetate must be used for anti-brittleness treatment. ④ The spinning yarn is boiled in clean water before coloring, and the embrittlement degree of the spinning yarn after testing is better than that of the lye boiled yarn. ⑤ The spinning yarn should be dried in time after coloring, because the wet yarn is simply heated during the stacking process, which reduces the content of anti-brittleness agent and pH value of the spinning yarn, which is unfavorable to anti-brittleness.

After drying, the spinning yarn should be cooled naturally, so that the temperature of the spinning yarn can be packed before falling to room temperature. Because it is not cooled after drying and packed immediately, the heat is not easy to distribute, which increases the energy for the decomposition of the dye and the acid, causing the possibility of the fiber to be brittle.

The selection of anti-brittle-Sulphur Black Br dyes, such dyes have been added to formaldehyde and chloroacetic acid when manufacturing, the resulting methyl – chlorine vulcanized anti-brittle-black, so that the easily oxidized sulfur atoms become a stable structural state, which can prevent the oxidation of sulfur atoms to generate acid and brittle fiber.