dye

Dyes are organic substances that enable the coloring of materials such as fibers. There are many kinds of dyes, which can be classified into natural dyes (such as vegetable dyes, animal dyes and mineral dyes) and synthetic dyes (or artificial dyes) depending on the source. According to the molecular structure, it can be classified into an azo dye, an anthraquinone dye, a phthalocyanine dye, an arylmethane dye, a nitro dye, and the like. According to the application method, it is divided into acid dye, basic dye, sulfur dye, reactive dye, disperse dye, direct dye and so on. The dye has a color, but the colored material is not necessarily a dye. The dye must have a chromophore and a chromophore. The dye in the ink should also have a water-soluble group such as a sulfonic acid group. Natural dyes are dyes obtained from animals, plants and minerals. According to the source can be divided into: 1 plant dyes, dyes extracted from the roots, stems, leaves and fruits of certain plants, such as indigo (blue) extracted from eucalyptus leaves, curcumin extracted from turmeric (yellow ), alizarin (red) extracted from alfalfa, etc. 2 animal dyes, dyes extracted from animal bodies, such as carmine extracted from cochineal. 3 mineral dyes, dyes extracted from mineral colored inorganic materials, such as chrome yellow, ultramarine blue, manganese brown and so on. Because natural dyes have many disadvantages compared with artificial dyes, such as incomplete chromatogram, inconvenient application, poor fastness, etc., most of them are eliminated except for a few. Synthetic dyes, also known as "artificial dyes". It is mainly processed by chemical processing of coal tar (or petroleum processing) fractionated products (such as benzene, naphthalene, anthracene, carbazole, etc.), sometimes called coal tar dye. Since several of the earliest synthetic dyes are made from aniline, they are also called "aniline dyes". Compared with natural dyes, there are many types of synthetic dyes, complete chromatograms, most of them are bright, washable and light-resistant, and can be produced in large quantities. So the current so-called dyes almost all refer to synthetic dyes. Its dyed products are one of the common judicial identification materials. There are two classification methods for dyes: The first one is a chromophore-based chemical classification method, which divides many dyes into azo dyes, sulfur dyes, anthraquinone dyes, steroid dyes, heterocyclic dyes, and phthalocyanines. There are 10 types of dyes and the like. The second type is based on the dye or fiber properties, dyeing dyes into acid dyes, neutral dyes, ice dyes, basic dyes, cationic dyes, direct dyes, reactive dyes, sulphur dyes, vat dyes and There are 14 other dyes and the like. There are many kinds of dyes, different in nature and widely used. However, most of the dyes used as physical evidence are fixed on textile fibers or paper, or as a tissue component of ink, ink, ball pen oil, and ink. Generally, after leaching, the comparison test is carried out by microchemical method, thin layer chromatography, liquid chromatography, ultraviolet-visible absorption spectroscopy and fluorescence spectroscopy. The world's dyes developed rapidly in the 1970s. Since the 1990s, new varieties and quality have been developed, and the annual output has remained at 1 million tons. Chinese dyes developed rapidly in the 1980s. In the 1990s, they also focused on improving quality. The output still maintained a certain growth rate, which was around 300,000 tons per year and 315,600 tons in 2000. Dyes are used for textile dyeing up to 85%, and the rest are used for coloring leather, plastics, paper, paints, etc.