The development history of dye processing technology
There are many varieties of dyes, but the physical form of their products is In other words, it can be divided into solid, liquid and slurry. It can also be further divided into:
Solid dyes – powder, granular, dust-free powder, block, flake, short column;
Liquid dyes—water-soluble liquids and dispersions;
Slurry dyes—solid/liquid mixtures.
Dye is an organic compound that often completes chemical reactions in the presence of liquid. For this reason, the world’s first synthetic dye was first sold in liquid form. Of course, initially The quality of the dye is far from what it is now, and it can only be considered the original form of today’s liquid dye. At that time, about 20% of the products were in liquid form, and these liquid dyes were mainly vat dyes and mordant dyes.
By 1923, the British first added selected additives to the original dyes and crushed them to form a dispersion of an aqueous solution of insoluble disperse dyes. By 1910, most dyes were processed into fine powders of a certain size after the water was removed.
According to literature in 1924, about 80% of dyes were processed into fine powder at that time, and vat dyes had been made into powders with a wide particle size distribution, from extremely fine to 50um. dye products. However, the original powder dyes had the disadvantages of serious dust flying and poor wetting properties.
After 1930, dyes in dispersion form have been further developed, but they still have the disadvantages of easy precipitation of dyes and poor storage stability.
The various properties of today’s liquid dyes have been significantly improved after optimizing the processing formula. The storage time can be more than half a year without deterioration. Liquid dyes are obtained with low processing costs and easy use. Growing.
Since 1950, the emergence of sand mills has promoted the development of post-processing technology. Using sand mills for wet grinding can obtain particles with finer particle size and narrower distribution. . The processing formula has been improved to make the basic particles of the dye reach about 1um. The quality of products produced using new processes and new equipment has been significantly improved, and the processing of non-water-soluble dyes has made great progress.
With the advancement of chemical machinery and equipment, granular dyes began to appear. The apparent particle size of granular dyes is 100~300um. There are hollow particles and solid particles. Its fluidity, wettability and dispersion are better than those of powdered dyes. At the same time, it overcomes the shortcomings of powdered dyes flying dust. This As soon as this dosage form appeared, it was immediately welcomed by the production and application departments. Now many dyes are processed into granular products.
Dye processing
The research content of dye processing technology mainly includes Determination and treatment of raw dyes, research on the performance of processing aids, design and selection of processing equipment and research on processing technology.
If post-processing technology is complex, it is mainly because its regularity is not strong, it has many individualities and few commonalities, and it is difficult to summarize quantitative rules. So people say that dye processing technology is a combination of science, technology and experience.
1. Dye processing has the following characteristics
① Processed varieties Many, because dyes are fine chemical products. Generally, the production tonnage is not large, there are many varieties, and the processing methods are different, so the process and equipment are quite complex;
②Dye factory needs Adjusting dosage forms or changing varieties according to market conditions requires that processing equipment should have certain adaptability, and production equipment should be multi-functional and have strong mobility;
③High technical content, Post-processing treatment includes many aspects and involves many professional knowledge. During the processing process, there are both physical changes and chemical changes, and many factors are both interconnected and mutually restrictive;
④ Product quality requirements are high. Commercial dyes have a number of economic and technical indicators, and some have formulated national standards. The production conditions are harsh and require stable operation. Operators should have high quality and a strong sense of responsibility.
2. Dye processing involves several aspects
2.1 Analysis of raw dyes
The analysis of raw dyes mentioned here refers to testing and analyzing the physical and chemical properties of raw dyes for the needs of dye processing. After years of research, it has been discovered that post-processing is by no means a simple physical process. Before dye processing, it is necessary to first analyze the intensity, color, hydrophilicity, crystal form, energy level, impurity content and many other indicators of the original dye. In order to determine Provide basic data for developing reasonable processing technology.
After the dye is synthesized, the raw dye filter cake is provided to the post-processing workshop through liquid-solid separation. After receiving the filter cake, the post-processing workshop first tests the raw dye.
Different dye varieties, different synthesis processes, and 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 A comprehensive measurement must be carried out, and only in this way can a correct processing method be formulated.
2.2 Processing aids
The so-called dye processing aids are During the post-processing process of dyes, the additives added can help improve the performance of specific dye commercial formulations (such as dispersion, thermal stability, dustproofness, anti-agglomeration, solubilization, etc.) or can help improve given properties (such as leveling, dyeing, etc.) Substances that promote dyeing, deepening, etc.) and the properties of dyeing on fibers (such as color fixation, softness, etc.), enhance heat resistance, maintain or improveA substance that stabilizes the dispersion, prevents dye aggregation, and helps improve dyeing levelness.
Commercial processing is inseparable from additives. Without understanding the performance of processing additives, it is impossible to optimize the processing formula. Correct use of additives can improve dye quality, reduce production costs, and increase the added value of dyes.
In recent years, the number of auxiliaries used in dye processing has grown to hundreds, with the largest dosage, and the number of dispersants that play an important role in the processing results is increasing year by year. , physical and chemical indicators and economic indicators are also different. For example, lignin dispersants can already produce multiple series of varieties with different molecular weights and different degrees of sulfonation. You can choose the most suitable variety according to your needs.
For the processing of water-insoluble (disperse, vat) dyes, a large number of additives need to be added to adjust the strength and other properties. There are many types of additives used in different dyes. The properties displayed are also different, and the additive performance and physical and chemical indicators determine its scope of use. Only by understanding the performance can we use it correctly. Studying the compatibility of additives so that they can play their best role in the formula is one of the contents of post-processing technology research.
2.3 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 successfully completing post-processing operations. It can be said that the development of post-processing technology is inseparable from the advancement 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 water-soluble dyes and improving purity. The development and application of ultra-fine grinding equipment can reduce the dye particle size to about 1μm. Drying technology and equipment are also widely used. Currently, there are many professional drying equipment manufacturers conducting research and development on dye drying equipment, and an independent industrial sector has been formed. Domestic drying equipment can basically meet the needs of dye drying.
In some literature, processing equipment is often classified into the category of chemical equipment and is regarded as a general equipment of chemical equipment. From the dye professional point of view, it should also be regarded as special equipment. Due to the characteristics of dye production and commercialization in dye processing and post-processing, these factors are very closely related. General equipment has no special effects when used. The quality of goods is highly dependent on equipment to some extent. Only Targeted design can bring out the maximum potential of equipment.
2.4 Processing technology
Processing technology It is a comprehensive application method of the above three parts. Practice has proved that the same raw dyes, auxiliaries and equipment can produce 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 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 interrelated and restrictive, and each one is indispensable. It can be considered that the comprehensive application effect of the above four factors is a concrete reflection of the level of post-processing technology.
</p
