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Why does reactive turquoise blue easily produce color spots and color stains?

Views:5     Author:Site Editor     Publish Time: 2021-05-21      Origin:Site Inquire

Cause:

 When the medium-temperature reactive turquoise blue is dip dyed, it is easy to produce color spots and stains, because the reactive turquoise blue has the defects of poor salt resistance and alkali solubility stability.

The meso-temperature reactive turquoise blue has good salt dissolution stability at the normal electrolyte concentration (<80g/L). The degree of agglomeration of the dye is not enough to harm the dyeing quality. Under the conventional concentration of soda ash (<25g/L), the alkali resistance and solubility stability are good, and the aggregation of dyes is not obvious. However, in the fixing solution where salt and alkali coexist, its solubility stability will be greatly reduced. After testing, the mixed concentration of salt and alkali in the fixing bath, once it is >80g/L, the dye in the dyeing solution will not only undergo significant or serious "flocculation", but also form dye-containing floccules on the surface of the dyeing solution. A lot of bubbles. Once these foams adhere to the fabric, they will cause color spots and stains.

 

There are two reasons for the flocculation of reactive turquoise blue in the fixing bath:

① In the fixing bath, salt and alkali coexist (soda ash is also an electrolyte), which greatly increases the concentration of sodium ions (Na+) in the dye solution. Due to the influence of the same ion effect, the degree of ionization of the hydrophilic groups in the dye It becomes smaller, which leads to a decrease in the hydrophilicity of the dye.

D-SO3 Na←→D-SO3+Na

Weak hydrophilicity Strong hydrophilicity

On the other hand, due to the greater hydration capacity of Na+, it can adsorb a large number of polar water molecules in the form of a direct or indirect hydration layer, thereby causing a greater salting-out effect on the dissolved dyes.

 

②In the alkaline bath, the β-hydroxyethyl sulfone sulfate active group in the dye will undergo an elimination reaction, and the sulfate group will fall off and become a vinyl sulfone group. Thus, the originally hydrophilic group becomes a hydrophobic group, and the water solubility of the dye itself is significantly reduced.


The hydrophilicity of the dye suddenly decreases, and the repulsive force of the water increases suddenly, and the dyes in the water aggregate with each other in order to obtain stability.


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