Causes of Color Spots Caused by Reactive Dye Properties（2）

Medium temperature reactive dyes

Medium-temperature reactive dye exhaust dyeing basically adopts conventional dyeing process. In fact, the dyeing properties of commonly used medium-temperature reactive dyes are not exactly the same, and there are three types.

First type

The performance characteristics are that in a neutral salt bath (color absorption bath), it has greater affinity and a higher primary color absorption capacity; it is not too sensitive to alkali agents, and the secondary color absorption is relatively mild in the initial stage of alkali fixation, resulting in "sudden dyeing" The phenomenon is not very prominent.

This type of dyes are mainly dyes containing heterobi-reactive groups, such as domestic medium-temperature reactive dyes with ternary colors.

Because this type of dye absorbs a higher amount of color at one time during the color absorption stage in the neutral salt bath, the concentration of the dye solution can be significantly reduced. In the early stage of alkali fixation, the degree of dye aggregation is relatively small, and the sudden dyeing phenomenon of the dye is relatively mild. Therefore, when dyeing using conventional processes, the performance defects of the dye itself are not enough to cause harm to the dyeing quality.

Second type

The performance characteristics are weak affinity in neutral salt bath (color absorption bath) and low color absorption amount at one time. However, it is sensitive to alkali agents. In the early stage of alkali fixation, the dye aggregation and flash dyeing phenomena are very prominent. This type of dye is mainly vinyl sulfone dye.

This type of dye has weak affinity in the neutral salt bath (color absorption bath), low color absorption capacity at one time, and is sensitive to alkali agents. In the early stage of color fixation by adding alkali, the dye aggregation and flash dyeing phenomena are prominent. If the conventional dyeing process is used for dyeing, during the alkali fixation process, the degree of dye agglomeration and flash dyeing can easily cause damage to the dyeing quality.

Third type

This type of dye is mainly based on high concentration C.1.5 reactive black KN-B (also known as reactive blue B, reactive navy B-GD) 60 to 80%, C.1.82 reactive orange 10 to 20%, plus Reactive black is mixed with a small amount of medium-temperature reactive yellow or reactive red.

About 1/2 of commonly used medium-temperature reactive blacks belong to this category. Such as: reactive black KN-G2RC, reactive black GR, reactive black GWF, reactive black S-ED, reactive black N, reactive black A-ED, B-ED, reactive black A-GEF, B-GEF, reactive black TBR , TFN, reactive black DS. There are also Yongguang reactive black GR-GRN, DyStar reactive black A, A-X, Jiayou reactive black EX-F, Jingren reactive black HF-FGR, Lihe reactive black GR, Ciba reactive black W-HF, W, etc. .

This type of reactive black has serious differences in the structure of the two blended components. Among them, C.1.5# reactive black is a disazo matrix containing a bisethyl sulfone active group. It has outstanding mid-temperature characteristics and is most suitable for color absorption and solidification at 60 to 65°C. color. The C.1.82# active orange monoazo parent contains vinyl sulfone and monochloro-s-triazine isobi-active groups. Its low temperature characteristics are significant and it is most suitable for color absorption and color fixation at 30-40°C, so the compatibility between the two is extremely poor. . If this type of reactive black is used as a medium-temperature dye (dyed at 60°C), it will inevitably have two major consequences due to the incompatibility of the performance of the reactive orange component. First, the color absorption and color fixation of reactive orange are too rapid and the color is uneven, and color flowers are easy to appear. Second, the hydrolysis of active orange is too fast. Slight differences in process factors (temperature, time, pH) will cause significant color differences due to different amounts of hydrolysis (because C.1.5# active black is actually navy blue, not black, active orange Black can be formed only after adding, and the remaining colors of orange and blue have mutual achromatic effects). Therefore, the amount of reactive orange coloring and the quality of level dyeing have a decisive impact on the dyeing results of reactive black (shade, blackness, and uniformity).

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