We have talked about some common quality question in the process of dyeing, and here let's see more dyeing problems, and better understand how to choose the right dyeing auxiliary in the dyeing process.
1. Color defect.
Color defect is the most common quality defect. The reason that cause it is as follows:
(1) the process and operation problem: the improper process and the wrong operation causes color defect.
(2) the equipment problem: the non-uniform temperature in the dry machine of the heat-set machine causes dolor defect. And the insufficient pump force of the rope dyeing machine also can cause color defect.
(3) Dye problem: if the dye concentrate and the solubility become bad, compatibility will become bad . It will become sensitive to the temperature and Ph value. and the color defect will occur. Such as, positive emerald blue HN-R is more likely to cause color defect.
(4) Poor water quality
The metal icon in the poor water will combine with the dye. And the impurity in the poor water will agglomerate with the dye. Both of them will cause color defect. The auxiliary related with the color defect is penetrating agent, leveling agent, chelating dispersant and PH value control agent. If the penetrating property is poor, the dyeing will not even. and the color defect will occur. Especially for the shattered cotton dyeing, cheese dyeing, heavy fabric dyeing, the penetrating agent is very important. Some manufactures only use JFC, but they fail to consider that the cloud point is among 38-42℃. If higher than 42 ℃,the penetrating ability will lose. And the quality problem will appear.
Leveling agent is classified into dacron-used, Cotton-used, wool-used, nylon-used,, acrylic-used and etc. And the quality is varied. Following items is need to be considered in the selection of leveling agent :the melting ability to dye, retarding and migration capacity, penetrating-helping property, complexional property to the metal ion in the water.
And the dyeing rate affected by PH value application, and bubble quantity. Leveling agent, no doubt, have the function of improving the color defect. Some manufactures choose non-icon surfactant, which will separated out above the cloud point and absorb the dye and form tarry material and stick on the fabric or equipment. And the quality problem will form. The quality of chelating dispersant have a import impact on the even dyeing. With the worse and worse water quality, the chelating dispersants impact on the even dyeing become more important. The controlling of PH value was not been concerned by most manufactures. For some manufactures, the ph value is different among different vat. and the using of some substitute acid makes uniform f value is difficult to reach. There are some plant using ph-shuffling agent to improve. But they do not know the relationship among temperature, time and Ph-shuffing agent. And the Ph-controlling is not act. So color defect continues to appear.
2. Color point (including white point)
The reason that cause color point is varied. For example,both no-dyeing immature cotton and solid sodium carbonate stuck on the fabric can caused white point. The reason that causes color point include:
(1) the wrong choice of dye. If the dye particle is larger or easy-to- agglomerate will form color point.
(2) the uncompleted melting of dye: the undissolved dye will stick on the fabric and causes color point.
(3) poor water: the poor water will cause dye agglomerate
(4) the unclean equipment. The tarry material of the dye vat drop on the fabric and causes color point.
(5) the wrong textile auxiliary: some additional auxiliary in the processing of dye causes dye agglomerate and the color point occurs. Too much bubble of the auxiliary will combine with dye and cause color point. Auxiliary separate out of the surface and combine with the dye, sticking on the equipment and fabric and cause color point.