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Why use Substitute alkali in reactive dyeing?

Views: 2     Author: Site Editor     Publish Time: 2022-08-30      Origin: Site


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Reactive dyes have been leading the way since their inception in 1956.

Reactive dyes have the advantages of easy to use, complete chromatogram, bright color, excellent fastness, level dyeing and good penetration.

In the past fifteen years, with the development of dyeing technology and fiber products, new requirements for reactive dyes have been put forward, and the research and development of reactive dyes has developed rapidly.

In particular, there have been great changes in varieties and application properties, and it has become the most important dye for cellulose fiber dyeing and printing.

As the world's largest printing and dyeing country, China has the highest total amount of textiles dyed with reactive dyes.

The dyeing process of reactive dyes includes two stages: dyeing and alkali-fixing.

In order to overcome the electrical barrier during dyeing, a sufficient amount of positively charged ions is required to promote dyeing, and an alkaline agent with sufficient buffering capacity is required to form a covalent bond between the dye and the fiber during color fixing.

The traditional fixation method of reactive dyes is to add a large amount of alkali after dyeing the fibers, so that the dyes can be covalently combined with the hydroxyl groups on the cellulose fibers under alkaline conditions.

The substitute alkali is a new type of environmental protection product developed for the high cost of fixing color with soda ash and trisodium phosphate in reactive dyeing and dyeing.

Substitute alkali is a mixed alkali, a buffer system composed of a variety of alkali agents and buffering agents. At present, there are two kinds of substitute alkalis on the market: solid and liquid.

Most of the manufacturers who have used the substitute alkali generally report that the solid is better, it is more stable, the difference between large and small samples is small, and the reproducibility of large products is good.

The general solid substitute base is the compound of inorganic base and organic base, such as sodium carbonate, sodium bicarbonate and sodium acetate, sodium formate.

Many manufacturers choose solid substitute alkali after trying several products, and use more substitute alkali buffer products with better effect among the solid substitute alkali.

The main raw material of general liquid substitute alkali is the product of chemical reaction between NaOH and organic fiber when people produce viscose silk.

The molecular structure of the organic base of the substitute alkali is different due to the different degree of reaction, which leads to the instability of the raw material, and the product also has a certain degree of instability.

Substituting alkali to replace soda ash for color fixing often has the following advantages:

The system is stable; good solubility, easy to dissolve in cold water, not easy to block the pipeline, shorten the fixing time, easy to wash and remove the residual alkali, and reduce the washing water.

It can effectively control the synchronous dyeing of color-blocking reactive dyes, and the dyeing fastness of the dyed products is equal to or even surpasses that of the soda ash dyeing products.

In recent years, domestic and foreign researchers have done a lot of research work on alternative alkalis, and have achieved great results.

Until today, Chinese researchers and domestic researchers are still in the stage of continuous adjustment and development of liquid mixed alkalis, in order to obtain liquid substitute alkalis with better application effects and environmental friendliness.

Let us look forward to the increasing use of alternative bases in reactive dyes in the future.

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