Sulphur black in dyeing

Sulphur black dye is insoluble in water, so sulfur dyes does not have dyeing capacity to cotton. But its in the sodium sulfide of aqueous reduced to leuco dyes for dyeing of cotton with good performance. So sulfur dyes are to be carried out in a solution of sodium sulfide. Sulphur black dye is more sulfur-containing polymer, which contain sulfur and disulfide bonds in the structure, but it is very unstable. Particularly the sulfur bonds in certain temperature and humidity conditions can be oxidized by the oxygen in the air as sulphur oxides, and further with water molecules in the air to produce sulfuric acid, thus reduce the yarn and fibre tendering, seriously fibers may all brittle into powders.
 
 
Sulphur black of cotton knit fabrics are difference from reactive black. First the two ingredients are different, the primary compose of reactive black is carbon, and sulfur black dye containing more sulfur, though their color is closer. Secondly, their uses are not the same, active black mainly used as adsorption materials, such as desiccant and air purification, while sulphur black are mostly used in dyeing of textiles.

Na2S is solvent to dissolve sulfur dyes, its role is to restore the sulfur black dye with leuco dye on cotton. Na2CO3 increase reduction stability role in sulfur black dye preventing dyes premature oxidation. It prevents the effects of calcium and magnesium salts in hard water staining when using hard water stain. General amount is 2% of the fabric, excessive amount may make fabric Red-Brown. Add Na2SO4 in dye solution are helpful to improve the dyeing.

But there are some notes in the operation.
1 to ensure time and temperature, ensure that the dye dissolve fully restored.
2 guarantee the temperature and time of germ cloth oil removal, removing grease from cloth to improve capillary effect and stain evenly.
3 wash water oxidation is the key.
4 soft: soft oil in the cylinder with water of 1:20

Environment-friendly liquid sulphur black mainly used in the denim yarn dyeing, cloth dyeing, knitting dyeing, package dyeing and so on. Compared with the activity, petroleum jelly and other dyes for cotton, it has the advantages of low cost and short process. And it has been increasingly accepted by the printing and dyeing factories. Read more!