Some colored organic compounds in nature can dye fiber materials, paper, leather and other substances into various beautiful and strong colors with proper methods. And some organic compounds with quite bright colors cannot be used as dyes because they have poor affinity to fiber materials, cannot be dyed by appropriate methods or have poor color fastness. Soluble in water or solvents. Or it can be transformed into a solution, or processed into a dispersed state, and has an affinity for the dyed substrate, can be adsorbed or dissolved in the substrate, and finally can make the dyed matter have a uniform color. The colored substance is called a dye. Therefore, dyes are organic compounds that can make the dyed object obtain a bright and firm color.
Different from this, the water-insoluble colored substance that can be coated on the surface of the material after preparation is called a pigment. Pigments are small particles of insoluble colored substances. The pigment is not adsorbed by the matrix like the dye, it is usually dispersed and suspended in the polymer material with binding ability, and the colored mixture of the metal complex dye can be adsorbed by the matrix. If the coloring process strictly requires that the colorant must be insoluble, pigments should be used, such as printing inks. If dyes are used, a bleeding ring will be formed on the border of the printing screen. Pigments should also have great opacity, hiding power and resistance to heat. This can be used for coloring paints and plastics. This chapter will focus on dyes without specifically introducing pigments.
Use of dye
Dyes are mainly used in the dyeing of various fibers (such as cotton, linen, wool, silk, leather and synthetic fibers, etc.), and are widely used in rubber, plastic, Ink, paper, food and photographic materials and other industries.
(1) Medical dyes are mainly used as cell dyeing substances.
(2) Biological dyes are used to elucidate protein structures and explore enzyme activity.
(3) Photosensitive dye In 1978, the silver consumption of photosensitive materials in various countries in the world was about 12,000, especially the silver content of X-ray film was higher. The use of cyanine dyes, the development of color photography has greatly improved the sensitivity and reduced consumption.
(4) Laser dyes Due to the wide spectral range of dyes, there are broad bands from near ultraviolet to near infrared, so that dyes can be applied to laser technology.
(5) Optical disc recording material, which records light and sound information on the optical disc material through the action of laser, and then displays the signal on the TV screen under the action of laser, Compared with the current magnetic tape video performance is more excellent. The dyes used in optical disc materials can also be used in solar cells.
(6) Liquid crystal dye development of electronic color display technology, especially liquid crystal color display, can lead TV technology to the direction of low energy consumption, miniaturization or super large screen , which requires liquid crystal dyes.
(7) Semiconductor dyes are used in photoresistors and spectrally sensitive detectors as components of electrophotographic recording materials.
From the above, it can be seen that dyes not only serve the material and cultural needs of the people in dyeing, but also play a role in the interpenetrating development of modern science and technology.
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