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What is the principle of sulphur dye dyeing cotton fabrics

Views: 4     Author: Site Editor     Publish Time: 2023-08-04      Origin: Site


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The use of sulphur dyes in all cotton textiles is indeed economical, and the color fastness is also good, but erythema and red strips are often generated, which requires rework, which affects yield and cost. To solve this problem, you must pay attention to the following points:


1. Make good use of sulfide (NA2S)

Sulfidine is the main additive for sulfur dye dye dyeing. Sulfur dye dye must be equipped with different proportion of sulfide (50%) according to the specific product. Generally, it is 1: 1 with dyes (folding into 100%), and sulfur -sulfur blue can also be matched with 1: 1.5. Its role is mainly to promote the dissolution and restoration of dyes. Sometimes the sulfide used is not reddish -brown, but it becomes gray and white powder, and it is also added to the dye bath together. In fact, the sulfurized alkali is gray -white powder. It has been weathering. Instead, it will not only fail to dissolve and restore the dye. On the contrary, premature dyes will be oxidized into color culverts. Wait for dye defects.


2. Control the chrome process conditions

Practice has proved that the immersion of sulfur dyes cannot be stained according to the theoretical so-called 80-85 ° C, especially sulfide and sulfide. After adding dyes and sulfonal alkali, you should gradually increase the temperature to 98 ° C, the preservation and staining 15-20min, and then stop the heating; the edge dyeing edges reduce the temperature in the cylinder to 80-85 ° C, continue to dye for about 20min, and then drain the liquid. Side in cold water to clean the oxidation. Regardless of the exclusion of residual liquid (heat) and adding cold water, the speed should be slow or too fast. This kind of dyeing method that is hot and then temperature is not only favorable to dye, but also the full dissolution and restoration of the dye, which can overcome the chromatis defective disease.


3. Slowly clean the dyes

As mentioned above, the dyed fabric cannot be cleaned in a cold water bath at once. Especially like vulcanized blue, it should be transitioned from the dye bath to mild, and even cleaning in water containing a certain reducing agent. The term is called "foot tank". This is not only conducive to the fully cleaning of the alkali and reducing agent on the fabric, but also the full hair color (oxidation) of the dye on the fabric. Of course, for some difficult oxidized dyes, such as vulcanized blue CV/3G, red brown GN, dark brown, etc., 1-2g/L sodium borate and hydrogen peroxide should be added to the 2-3-cylinder water bath to promote the full dyes to make full full dyes. Oxidation hair color.


4. Pay attention to the stability of the dye bath and solve the problem before the out of the tank

Sulfur dyes are a dye with more sulfur content, especially as black, and there are many factors that are unstable when applying. If the hidden color of the dyeing bath is dark green or turmeric (depending on the variety of dye, the hidden color is different) when the dyeing bath is different). It's right. Then, you cannot get out of the tank. Generally speaking, the original number of sulfide is 1/2 or 1/3, and then about 85 ° C, continue to dye 10-15min. Then go out again. Otherwise, problems will occur after the cylinder, resulting in rework. Practice has proved that when dyeing, if you add 2-3g/L baking soda, soda, glucose (industrial grade) or 0.5-1g/L insurance powder and 1-2g/L urea, you can promote dye dissolution and stabilize the dye bath to stabilize , Significantly reduce the chance of producing erythema and red bars.


5. Fix the repair of defective diseases such as erythema and red bars

Generally, the dilute solution (about 5-10g/L) of sulfide (about 5-10g/L) is treated at 85-90 ° C for 20 minutes, and defective disease can be eliminated. When defective diseases are serious, the amount of sulfide should be increased accordingly. When the amount of sulfid alkali is more than 10g/L, the appropriate amount of dyes should be increased in the bathing bath. Otherwise, although defective diseases such as erythema have been repaired, the color may become lighter. The specific amount and method of repair depends on the actual situation.

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