Why Is Your Fabric Prone To Hue Problems During The Rainy Season?
May 18, 2019
For the textile printing and dyeing industry, the standard of industrial water is generally used, and the water quality often varies with seasons, regions and climate changes. Especially in summer, the rainwater is relatively sufficient, and the water quality changes are relatively large and relatively fast, which is easy to have adverse effects on printing and dyeing.
Effect of metal in water on dyeing of disperse dyes
Abbreviation for water quality and water quality. It marks the physical properties of water bodies (such as color, turbidity, odor, etc.), the chemical (inorganic and organic content) and the characteristics of organisms (bacteria, microbes, plankton, benthic organisms) and their composition. To assess the quality of water quality, a series of water quality parameters and water quality standards, such as water quality standards for drinking water, industrial water and fishery water, are specified. For the printing and dyeing industry, the standard of industrial water is generally used, and the water quality often changes with seasons, regions and climate changes. Especially in summer, the rainwater is relatively sufficient, and the water quality changes are relatively large and relatively fast, which is easy to have adverse effects on printing and dyeing.
If the content of metal (such as rust) or metal ions in dyeing water exceeds the standard, it will affect the dyeing quality and fail to meet the specified hue requirements.
The main reasons for the change in hue are:
1. The metal ion is combined with the dye;
2. Metal or metal ions reduce and decompose the disperse dye;
3. The action of metal ions and auxiliaries in the dye bath affects the dispersion stability of the dye and reduces the dye uptake rate.
Dyes that are prone to metal ions combined with disperse dyes are only a minority.
For example, an anthraquinone type disperse dye, in which a quinone-based brilliant red dye, is converted from red to red with blue due to the combination of metal ions and disperse dyes. The degree of binding of metal ions to dyes is related to the type of metal ions. Fe2+, Fe3+, and Cu2+ have a great influence on dyes. Ca2+ and Mg2+ (the hardness of water generally indicates the concentration) have relatively small effects on dyes, but when the concentration is relatively high, It also has an adverse effect on dyeing.
In the dyeing, in order to prevent the influence of metal ions, a metal chelating agent may be used, and for 2+, Fe3+, Cu2+, an EDTA or NTA-containing metal chelating agent which is effective in an acid-neutral dyebath may be used. For the Ca2+ and Mg2+, a polycarboxylic acid metal chelating agent can be generally used.
However, the reduction reaction caused by metal ionization cannot be solved by using a metal chelating agent, and another solution must be solved. If the iron powder contained in the dye bath is ionized to Fe2+, Fe3+, and the ions are chelated by the metal chelating agent, the use of the metal chelating agent alone cannot prevent the dye from being reduced.
The use of an oxidizing agent can effectively prevent the effect of reduction, but the dosage is appropriate. When the content of Fe2+ in the dyebath is 500 ppm, 1 g/L of sodium chlorate may be added. If the amount is too large, the oxidizing property of sodium chlorate adversely affects the dye, so it is undesirable to use sodium chlorate. When the metal content is small, it is possible to prevent reduction by using m-nitrobenzenesulfonate (anti-staining salt S) or the like.
The acid dyebath is easy to cause the reduction of iron powder or Fe2+. To prevent the quality of dyeing caused by reduction, attention must be paid to the quality of dyeing water and the selection of dyeing auxiliaries. In addition, the oxygen in the air in the dyeing machine and the oxygen in the dyeing bath help to prevent reduction, and the seal press dyeing of the sealed dyeing machine is also very effective.
