What aspects are involved in dye processing

1 Analysis of primary dyes

The original dye analysis mentioned here refers to the testing and analysis of the physical and chemical properties of the original dye for the needs of dye processing. After years of research, it is found that post-processing is by no means a simple physical process. Before processing the dye, it is necessary to analyze many indicators such as the intensity, shade, hydrophilicity, crystal form, energy level, and impurity content of the original dye. Provide basic data for a reasonable processing technology.

After the dye is synthesized, the original dye filter cake is provided to the post-processing workshop through liquid-solid separation. After the post-processing workshop receives the filter cake, the original dye is tested first.

Different dye varieties, different synthesis processes, even different manufacturers of the same variety, and different production batches of the same manufacturer may have some differences in product quality. Each batch of dyes must be fully measured, and only in this way can a set of correct processing method.

2 Processing aids

The so-called dye processing auxiliaries are added in the post-processing process of dyestuffs to help improve the performance of specific dye commodity formulations (such as dispersibility, thermal stability, dust resistance, anti-agglomeration, solubilization, etc.) Substances that fix properties (such as leveling, dyeing promotion, deepening, etc.) and the properties of dyeing on fibers (such as color fixing, softness, etc.), enhance heat resistance, maintain or improve dispersion stability, prevent dyes from agglomeration, and help Substances for improving the levelness of dyeing.

Commercial processing is inseparable from additives, and it is impossible to optimize the processing formula without understanding the performance of processing additives. Correct use of auxiliaries can improve the quality of dyestuffs, reduce production costs and increase the added value of dyestuffs.

In recent years, there have been hundreds of kinds of auxiliaries used in dye processing, with the largest amount, and the varieties of dispersants that play an important role in the processing results are increasing year by year, and the physical and chemical indicators and economic indicators are also different. For example, lignin dispersants have been able to produce several series of varieties with different molecular weights and different degrees of sulfonation, and the most suitable varieties can be selected according to needs.

For the processing of water-insoluble (dispersed, vat) dyes, it is necessary to add a large amount of additives to adjust the strength and other properties. There are many kinds of additives, and the properties shown in different dyes are also different. As well as physical and chemical indicators determine his scope of use. Only by understanding the performance can it be used correctly. Researching the compatibility of additives to make them play the best role in the formulation is one of the contents of post-processing technology research.

3 Processing equipment

Processing equipment (post-processing equipment) is an important means to complete post-processing operations. Reasonable design and selection of processing equipment are the primary conditions for successful post-processing operations. It can be said that the development of post-processing technology is inseparable from the progress of equipment.

In other words, the development of equipment is also promoting the continuous development of post-processing technology. In dye processing, the use of ultrafiltration and reverse osmosis membranes plays an important role in desalting and improving the purity of water-soluble dyes. The development and application of ultra-fine grinding equipment can reduce the particle size of dyes to about 1 μm. The application of drying technology and equipment is also very extensive. At present, there are many professional drying equipment manufacturers carrying out the development and research of dye drying equipment, and an independent industrial sector has been formed. The domestic drying equipment can basically meet the needs of dye drying.

In some literatures, processing equipment is often classified into the category of chemical equipment, and it is regarded as a general equipment of chemical equipment. From the professional point of view of dyestuffs, it should also be regarded as special equipment. In the post-processing of dyestuffs, due to the characteristics of dyestuff production and commercialization, the relationship between these factors is very close, the use of general equipment has no special effects, and the quality of goods has a strong dependence on the equipment to some extent, only Targeted design can bring out the maximum potential of the device.

4 Processing technology

The processing technology is a comprehensive application method of the above three parts. Practice has proved that the same original dyes, auxiliaries and equipment can obtain completely different results using different processing techniques, which shows the importance of process conditions. It is not difficult to see from the above introduction that these four aspects mark the technical level of post-processing.

Many large foreign companies have their own professionals engaged in research work in this area, and some even have more personnel engaged in post-processing technology development than synthesis personnel. If the post-processing process is reasonable, the purpose of reducing production costs, protecting the production environment and improving product quality can be achieved.

These four factors are both interrelated and mutually restrictive, and none of them is indispensable. It can be considered that the comprehensive application effect of the above four factors is the concrete embodiment of the post-processing technology level.