There are many kinds of dyestuffs, but in terms of the physical form of their commodities, they can be divided into solid, liquid and slurry. It can 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.
Dyes are organic compounds, which often complete chemical reactions in the presence of liquids. For this reason, the world's first synthetic dyes were first sold in liquid form. Of course, the quality of dyes at first was far from the current ratio, and can only be considered as The original form of liquid dyes today. At that time, about 20% of the commodities were liquid, and these liquid dyes were mainly vat dyes and mordant dyes.
By 1923, the British first added the selected auxiliary agent to the original dye and crushed it to make a dispersion of insoluble disperse dye aqueous solution. By 1910, most dyes were processed into fine powders of a certain size after removing the water.
According to the literature in 1924, about 80% of the dyes were processed into fine powder at that time, and vat dyes have been made into powdery dye products with a wide particle size distribution, ranging from extremely fine to 50um. However, the initial powdery dyes have the disadvantages of serious dust flying and poor wetting performance.
After 1930, dyes in dispersion form were further developed, but there were still the disadvantages of easy precipitation of dyes and poor storage stability.
The various properties of the current liquid dyes have been significantly improved after the optimized processing formula, and the storage time can reach more than half a year without deterioration. The liquid dyes have been continuously developed due to low processing costs and convenient use.
Since 1950, the appearance 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. And the processing formula has been improved, so that the basic particles of dyes can reach about 1um, the quality of products produced by new technology and new equipment has been significantly improved, and the processing of water-insoluble dyes has made great progress.
With the progress of chemical machinery and chemical equipment, granular dyes began to appear. The apparent particle size of granular dyes is 100~300um, and there are hollow particles and solid particles. Its fluidity, wettability and dispersibility are better than those of powdery dyes, and at the same time it overcomes the shortcomings of powdery dyes flying dust. The dosage form was immediately welcomed by the production and application sectors, and many dyes are now processed into granular commercial products.