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What is alkaline dyeing with disperse dyes?

Date:Mar 22, 2021

Dyeing polyester with disperse dyes is generally carried out under acidic conditions. The selected disperse dyes that can be dyed in alkaline conditions have the following advantages and disadvantages:



1. The appearance of alkaline dyeing with disperse dyes:


When dyeing conventional polyester with disperse dyes, the dyeing bath is generally controlled to be acidic (pH 5-6). Because of dyeing under acidic conditions, most of the disperse dyes have the purest shade and higher dye uptake. However, polyester simulated silk fabrics must be treated with alkali weight reduction to produce cavities on the fiber surface, which can further improve the feel, gloss and drape. However, the fabric after alkali weight reduction is neutralized and washed with water. It is still unavoidable that it is alkaline, so the disperse dye alkaline dyeing method appears. The disperse dyes that can be dyed in the alkaline bath are called disperse dyes for alkaline dyeing.



2. The advantages of disperse dye alkaline dyeing:


The alkaline dyeing method has the advantages of effectively removing oligomers, shortening the dyeing time, stabilizing the color and saving energy and so on.


1. It can further improve the refining effect:

Because there are more oils on synthetic fibers, it is difficult to completely remove the remaining oils, slurries, etc. with the existing scouring method, so it is easy to cause uneven dyeing and even color stains, and the dye bath is alkaline in alkaline dyeing. , At the same time, add alkaline leveling agent, which has degreasing and desizing effect, can effectively improve the problem of insufficient washing in the pre-treatment process, and is beneficial to the rationality and simplification of the dyeing process.


2. It can prevent the reattachment of the residue of the alkali weight reduction dispersion:

For synthetic fabrics to have a soft feel and high quality, intermittent alkali weight reduction is an ideal method, but its decomposition products and caustic soda are difficult to be completely cleaned, resulting in an increasing concentration of dispersion residues in the working fluid. The higher is, if dyeing in an acid bath, the residue of the dispersion will easily re-stain and cause stains. When dyeing in an alkaline bath, the residue of the decomposition product can be dissolved in the dyeing bath, which can prevent the alkali from reducing the residue of the dispersion. The re-attachment.


3. It can prevent the agglomeration of oligomers:

There are some cyclic linear oligomers in polyester. During dyeing, these oligomers transfer to the surface of the fiber, fall off into the dyeing bath, and are easy to agglomerate and adhere to the fabric or cylinder. In the alkaline dyeing bath, due to low The polymer is soluble in alkaline solution and will not cause dyeing quality problems.


4. It can improve the quality of dyeing products and the reproducibility of dyeing:

When dyeing under acidic conditions, the surface of polyester fabric has a rough feel, while under alkaline conditions it has a sense of lubricity. Therefore, when dyeing in an alkaline bath, it can reduce the wrinkles that are easy to appear in the acid dyeing bath. Problems such as scratches, scratches, etc., and can also give the dyed fabric a soft touch, thereby improving the quality of the dyed product. At the same time, the application of alkaline leveling agent has an excellent buffering capacity for the pH value in the dye bath, so that the dyeing After the pH value is basically the same, it is helpful to reduce the tank difference and improve the reproducibility of dyeing.