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Alkaline Dyeing Of Disperse Dyes

Date:Oct 14, 2019

First, the appearance of disperse dye alkaline dyeing:


When the disperse dye is dyed with conventional polyester, the dye bath is generally controlled to be acidic (pH 5-6). Most of the disperse dyes have the purest color and higher dye uptake due to dyeing under acidic conditions. However, the polyester artificial silk fabric must be treated with alkali to reduce the surface of the fiber, so that the hand feels soft, luster, drape and the like are further improved, but the fabric after alkali reduction is neutralized and washed on the fabric. It is still inevitable to have alkalinity, so there is a disperse dye alkaline dyeing method, and a disperse dye which can be dyed in an alkaline bath is called a disperse dye for alkaline dyeing.


Second, the advantages of disperse dye alkaline dyeing:


Alkaline dyeing has the advantages of effectively removing oligomers, shortening dyeing time, stabilizing color and saving energy.


1, can further improve the refining effect:

Since the synthetic fiber has more oil agent, it is difficult to completely remove the residual oil agent, slurry, etc. by the existing scouring method, so that the dyeing unevenness or even the color flower is easily caused, and the dyeing bath is alkaline when the alkali dyeing is performed. At the same time, an alkaline leveling agent is added, and the leveling agent has the effect of removing oil and desizing, which can effectively improve the problem of insufficient washing in the pretreatment process, and is beneficial to the rationality and simplification of the dyeing process.


2, can prevent the re-adhesion of the residue of the alkali reduction dispersion:

In order to obtain a soft hand and a high quality, the synthetic alkali reduction is an ideal method, but the decomposition products, caustic soda, etc. are difficult to be completely washed, resulting in a concentration of the dispersion residue in the working fluid. The higher the dyeing is in the acid bath, the residue residue is easily smeared to cause tinge, and in the alkaline bath, the decomposition residue is soluble in the dyebath, thereby preventing the alkali-reduced dispersion residue. Re-attachment.


3, can prevent the condensation of oligomers:

There are some linear linear oligomers in the polyester. During the dyeing, these oligomers are transferred to the surface of the fiber, and fall into the dyebath, which is easy to aggregate and adhere to the fabric or the cylinder; in the alkaline dyebath, due to the low The polymer is soluble in an alkaline solution and does not cause quality problems in dyeing.


How to solve the problem of polyester oligomers perfectly?


4, can improve the quality of dyeing products and the reproducibility of dyeing:

When dyeing under acidic conditions, the polyester fabric has a rough feel on the surface and a lubricious feel under alkaline conditions, so when it is dyed in an alkaline bath, wrinkles that are prone to occur in an acid dye bath are reduced. Problems such as scratches, scratches, etc., and also give the dyed fabric a soft hand, thereby improving the quality of the dyed product. At the same time, the alkaline leveling agent is used to have an excellent buffering capacity for the pH value in the dyeing bath, so that the dyeing is dyed before dyeing. After the pH value is basically the same, it is beneficial to reduce the cylinder difference and improve the reproducibility of dyeing.


Third, the disadvantages of disperse dye alkaline dyeing:


Since the conventional disperse dye structure contains an ester group, an amide group, a cyano group or the like, the dye is easily hydrolyzed under neutral or alkaline conditions, resulting in color change of the dye and loss of dye strength. Therefore, alkaline dyeing requires screening of the dye.


4. Disperse dyes that can be screened for alkaline dyeing:


1. Dianix AC_I and Dianix UP-H dyes from DyStar, but the alkaline stabilizer JPH95 should be used in the use. The stabilizer has good cushioning ability and can make the dyeing bath always in the dyeing process. Maintaining a pH of 9.5±0.5, and having excellent chelating property and masking metal ionicity, it can effectively protect the dye from decomposition and dissolve oligomers in polyester.


2. Kayalon polyester yellow E-3GL, orange E-2GL, red E-2GL and blue E-BR of Nippon Chemical Pharmaceutical Co., Ltd. are suitable for dyeing light primary colors; Kayalon polyester yellow brown 3RL 200, Kayalon polyester red jade 3GL- S, Kayalon polyester blue 2R-SF, suitable for dyeing the three primary colors of dark.


3. Sumitaron Yellow SR, Red E-3BR, Blue ER and other three primary colors of Sumitomo Corporation of Japan and Miketon polyester MQ series of disperse dyes from Mitsui East Asia of Japan can also be used for alkaline dyeing. These dyes mainly include hydrazine and heterocyclic type. .


The above dyes were dyed in an alkaline bath and dyed in a weak acid bath for comparison. The K/S values of the above various dyes were all above 95%, and the color difference was 4 to 5.


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