Hardness
It is generally believed that the hardness below 50ppm has no effect, and 20ppm is already very good water.
The quality of cheese dyeing water is no more than this, but the content of copper and iron ions in the water should be paid attention to.
Usually reactive dyeing is better when it is below 50ppm. The key is the content of metal ions, especially iron ions, which will cause changes in color and light. It is recommended to measure the conductivity of the water.
Wastewater that meets the standards is reused in bleaching and dyeing production. The main reason why products are prone to color stains is that the conductivity of the water is relatively high; when reusing bleaching and dyeing wastewater, attention should be paid to the conductivity of the wastewater. . Conventional sewage treatment methods cannot effectively remove metal ions that cause high conductivity of wastewater, and must be removed through reverse osmosis membrane treatment.
Water hardness that is too hard will form water stains on the boiler wall. The calcium and magnesium ions in the water can precipitate and stain soap. Unevenness, poor fabric feel, and yellowing of the fabric. Reduce the activity of desizing enzymes, reduce the solubility of sizing materials, and are incompatible with the chemical agents in the finishing formula.
As treatment method, you can use EDTA or sodium tripolyphosphate. Try the dosage of 2g/l. It is better to buy dedicatedMetal ion blocking agent; if the dyeing water is not softened, or the thick cloth often contains metal ions, it often causes uneven (undesirable) dyeing. Therefore, adding chelating dispersants during the dyeing process prevents the influence of metal ions and can promote the dyeing process. Remove the effect.
However, chelating and dispersing agents such as EDTA (ethylenediamine diacetic acid), DTPA, NTA, phosphate, gluconic acid, etc. may chelate out the metal ions in the dye, causing a decrease in light fastness and discoloration of the legs. .Therefore, some netizens recommend polyphosphates and polyol acids as chelating dispersants.
Example:
The water used for dyeing cotton in the on-site factory is groundwater, which has not been softened or filtered. A layer of dirt is clearly visible on the yarn dyed before. Now a small amount of bleaching powder is added to the water, which has slightly improved it. , but after the tube yarn is dyed The bottom layer in all cases feels astringent, and the color is light and dark. The forward and reverse adjustments have been made, and water softener has been added, but the effect is not obvious. After further verification, there is a layer difference in water hardness at the bottom of the pre-scouring process of about 130ppm.
Reason:
The water quality is too hard and the groundwater is used to dye the yarn. The water quality is too hard and there are too many impurities, which may cause the inner layer of yarn in your dyed yarn bobbin to become dirty. A good solution is to pump out the groundwater first. Let the water settle on the ground, soften the water, and then filter the water with a filter, so there will be no problem, but the investment will be larger.
Impurities and microorganisms
Cationic film working fluid is unstable in river water. It flocculates with microorganisms in the river water, producing yellow floc that sticks to the fabric. After drying and setting, yellow spots will be formed on the fabric. , so we can know why quality problems are particularly likely to occur in May and June when the temperature is more suitable for algae reproduction, but such situations rarely occur in autumn and winter.
The quality of the water has a great impact on the stability of the softening working fluid and the whiteness of the fabric after softening.Large impact, so printing and dyeing factories try to use treated water during production.
Some manufacturers use activated carbon filtered A similar situation will still occur when it comes to water quality. This is because the microorganisms are very small and the activated carbon cannot completely adsorb and filter. Therefore, adding cationic surfactants to the sedimentation tank before water treatment allows it to flocculate with microorganisms in the water, and then filtering through activated carbon can improve the effect of water treatment; in addition, activated carbon must be cleaned or replaced regularly.
If the above method is not feasible or cannot be eliminated For quality issues, it is recommended that the manufacturer use non-ionic or anionic film when algae reproduction is strong, or use non-ionic film combined with silicone oil to improve the feel.
In manufacturers that produce more macular spots, this has not happened when using amino silicone oil for finishing.
Winter is not a good sign for printing and dyeing factories, and the water quality is poor.
p H value
For reactive dyeing, when the pH value is 7~9, the color difference of the product is normal, indicating that this pH value range has little effect on the color difference of the product, and the presence of a small amount of alkali will not change or destroy the color base of the reactive dye molecules.
When the pH value is 8.5, the soaping color fastness and wet rubbing fastness of the fabric are level 3, which cannot meet customer requirements; when the pH value further increases, the color fastness becomes worse, which shows that the alkali in the water The increased color fastness will affect the color fastness of dyed products
The incoming water quality of sewage reuse plants generally requires a pH value <9 to ensure that the microbial growth of the treatment system is not harmed by alkalinity and can operate normally. The quality standards for reused water require a pH value below 85, preferably close to 7.
Salinity
The salt in the reuse system is mainly sodium sulfate, which comes from two sources:
(1) Added as a dye accelerator in the dyeing process;
(2) Blanching and color fixing process The added caustic soda and soda ash are converted into sodium sulfate after neutralization with sulfuric acid
The limit salinity in the reuse system is 924mg/L, which does not affect the dyeing quality of fabrics.
iron ion
Pre-treatment iron ions will cause hydrogen peroxide to gather and accelerate decomposition, resulting in holes on the cloth surface.
Iron ions will cause the dyed fabric surface to darken and color spots will easily appear. As for the removal method, it first depends on the content. Generally, if it is below 15ppm, it does not matter. If it is slightly higher, chelating agent can be added.
Chloride ion
Simple chloride ions have no effect on reactive dyeing, because some people use salt as a dye accelerator, but it has an impact on the body of the dye vat. It depends on the dye vat you use. Whether the steel is chlorine resistant.
If it is like tap water, it contains effective chlorine used for bleaching and sterilization, and if it exceeds a certain standard, it will affect the dye.
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