By 1923, the British first added the selected auxiliary to the original dye and pulverized it to make a dispersion of an insoluble disperse dye aqueous solution. By 1910, most dyes were processed into fine powder with certain specifications after removing water.
According to the literature in 1924, about 80% of the dyes were processed into fine powder at that time, and the vat dyes had been made into powdered dye products with a wide particle size distribution, ranging from extremely fine to 50um. However, the original powdery dyes had the disadvantages of serious dust flying and poor wetting performance.
After 1930, dispersion-type dyes have been further developed, but there are still disadvantages such as easy dye precipitation and poor storage stability.
The current performance of liquid dyes has been significantly improved after optimized processing formulas. The storage time can be maintained for more than six months without deterioration. Liquid dyes have been developed with low processing costs and convenient use.
After 1950, the emergence of sand mills has promoted the development of post-treatment technology. Wet grinding with sand mills can obtain particles with finer size and narrower distribution. And improved the processing formula, so that the basic particles of the dye reached about 1um, the quality of products produced by the new process 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 have begun 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 powdery dyes, and it also overcomes the shortcomings of powdery dyes flying. This formulation was immediately welcomed by the production and application departments, and many dyes are now processed into granular commodities.