Functional dyes are a type of dyes with special functionality or special expertise. This special function is usually related to the light, electricity, heat, chemistry, biochemistry and other properties associated with modern high and new technology fields. This type of dye absorbs very little energy and can produce certain special functions. Therefore, it is used in small quantities and at a high price, and has significant economic benefits.
Currently, functional dyes have been widely used in liquid crystal displays, heat-sensitive pressure-sensitive Recording, optical disc recording, photochemical catalysis, photochemical therapy and other high-tech fields. All major dye companies in Japan regard the production of functional dyes as the focus of their respective development. In addition to photography, electrostatic copying, copying and other varieties, domestic functional dyes have almost no applications in other fields, or are still in the trial production stage, and have not attracted enough attention. In particular, the application of functional dyes in dyeing and finishing has only just begun to take shape, and its research, manufacturing, application, and management levels are still far behind those of advanced countries. It should be said that functional dyes are a valuable tool for dye workers and dyeing and finishing workers. Strive to explore new areas.
1 Classification and development approaches of functional dyes
1.1 Functionality Classification of dyes
Functional dyes are in a stage of rapid development, and their classification is not yet unified. They can be classified as follows according to their functions.
Color-changing isomeric dyes: photochromic, thermochromic, electrochromic, wet-chromic, pressure-sensitive (pressure-sensitive) color-changing dyes Energy conversion dyes: luminescence, solar energy conversion, laser, organic Dyes for nonlinear optical materials, etc.
Functional dyes
Dyes for information and display recording: liquid crystals, color filters, optical information recording, electronic copying, Dyes for inkjet printing (printing), etc.
Biochemical and medical dyes: for biological coloring, medical dyes, etc.
For chemical reactions Dyes: dyes for catalysis, chain termination, etc.
1.2 Development approaches of functional dyes
There are two main ways to develop functional dyes: one is to screen original dyes and utilize certain potential properties of traditional dyes and pigments. The second is to change the color system of traditional dyes to give them new functions.
2 Application of functional dyes in textile dyeing and finishing
Currently , Photochromic dyes, fluorescent dyes, infrared absorption and camouflage dyes, thermochromic dyes, moisture-sensitive (heat-sensitive) coatings, electrochromic dyes, special colored polymers, metal ions, solvent-chromic dyes, far-infrared thermal insulation coatings and other functional dyes It has entered the practical stage in textile dyeing and finishing or has shown its potential application prospects.
2.1 Photochromic dyes and pigments
Have “photochromic properties” (i.e. the color of a substance changes with light)” compounds are called “photochromic dyes (pigments)”.
There are not many photochromic dyes used directly in textiles. The main reason is that the light fastness of these dyes is not ideal, the price is relatively expensive, and their affinity for fibers is not high. It is difficult to process through conventional dyeing and printing processes. However, the author predicts that with the development of textile dyeing and finishing processing technology and photochromic dyes, photochromic textiles will gradually mature.
2.2 Fluorescent dyes and pigments
The definition of fluorescent dyes has not yet been Generally speaking, dyes that can strongly absorb and radiate fluorescence in the visible light range are called fluorescent dyes. Fluorescent pigments are essentially resin solid solutions of very fine-particle fluorescent dyes.
Rhodamine and its derivatives are the earliest fluorescent dyes used in textiles. They can dye silk, polyester, nylon and other natural or synthetic fibers to obtain eye-catching colors and effects. , Fluorescent yellow tennis balls are made of fluorescent yellow dye dyed on the surface fiber material of tennis balls.
Fluorescent pigments are mainly used for printing or coating processing on textiles, and are used for clothing or textile products that require bright colors, such as travel supplies, sportswear and children’s clothing. At present, this type of pigment has become increasingly popular.
2.3 Infrared absorbing dyes and infrared camouflage dyes
Infrared absorbing dyes It refers to dyes that have strong absorption of infrared rays. Like ordinary dyes, these dyes also have a specific Л-electron common orbital system. The difference is that their first excitation energy is relatively low, and they absorb not visible light but longer wavelengths. of infrared rays. Infrared camouflage dyes (or pigments) refer to dyes with specific colors whose infrared absorption characteristics are similar to those of the natural environment. The difference from ordinary dyes is that their infrared absorption characteristics are similar to those of the natural environment. They can camouflage dyed objects and make them difficult to detect. Discovered by infrared observation.
In recent years, near-infrared absorbing dyes closely related to textile dyeing and finishing have been used for solar energy conversion and storage. Plastic films or textile clothing processed with this dye (or pigment) have good application prospects in industry, agriculture and clothing.
Infrared camouflage dyes (or pigments) are mainly used for camouflage of military equipment and combatants. Since infrared camouflage research is highly confidential in various countries, relevant technologies are rarely published. Information obtained from relevant patent documents shows that a small number of screened vat dyes not only have good infrared absorption properties, but also have various color fastness properties. The strength can also meet the requirements of military textiles.
Pigment transfer technology, commonly referred to as pigment transfer technology, is still very promising.
3.5 Functional dyes for biochemistry and medicine
Functional dyes in biology It has a long history of application in chemistry. Mainly used for cell coloring, sterilization, enzyme purification and analysis, etc. The antibacterial and antiseptic properties of dyes are of great significance to the processing of textiles with hygienic functions. Textiles dyed with such dyes can not only meet certain color requirements, but also have antibacterial and antiseptic functions. Therefore, textiles dyed with some functional dyes have medical and health care functions, and it is very meaningful to carry out research in this area.
3.6 Functional dyes for laser radiation
Laser is currently mainly used in In communications, medical care, spectroscopy, photochemistry, reaction kinetics research, isotope separation, trace analysis, and military industry, its processing and application in textile dyeing and finishing has also become a new trend, such as laser engraving, fiber laser modification , and functional dye printing with laser radiation, etc.
4 Conclusion
The types and functions of functional dyes vary with each Research in the field is constantly expanding. This article only introduces some dyes that have been or are being developed and applied. In addition to these, in fact many organic compound dyes with conductive, magnetic, catalytic and other properties belong to the category of functional dyes.
The author believes that the application of functional dyes will have broader prospects, and most of them are related to high technology and New product development is closely linked. The dyeing and finishing industry is the most important sector in the traditional application of dyes. In the past, the light and color properties of dyes were mainly used. In the future, although the fields of light and color will still be inseparable, in the process of developing new products, especially fiber products for industrial use, attention will be paid to the multi-faceted performance of dyes. Therefore, the application of functional dyes in the textile dyeing and finishing industry will be very potential.
References
〔1〕Duff J M, Hor A M, Loutfy R O, et al. Squaraine Chemistry of functional dyes. Proceedings of the Second International Symposium on Chemistry of Functional Dyes, Japan, 1992,2:564-571.
〔2〕 Zhang Daquan, Su Jianhua, Tian He, Chen Kongchang. Application of photochromic dyes in optical information materials. Dye Industry〔J〕. 1997,34(5): 18.
〔3〕Matsuoka Ken. Chemistry and application of pigments. Dainippon Books〔M〕.1994.
〔4〕Tian He. Optical and electrical functional organic dyes. Shanghai Dyes〔J〕.1998,26(3): 1-6.
Non-Impact Printing Technologies, Japan, 1992.284.
〔5〕Law K Y, Tarnawskyj T W, Popovic Z D. Azo pigments and their intermediates, a study of the structure-sensitivity relationship of photogenerating bisazo pigment in bilayer xerographic devices. J Imaging Sci Technol, 1994,38:118.
〔6〕Xie Lanjing. Application and industrialization of several functional dyes in Japan. Chemical Materials〔J〕.1992, (2): 34-37.
About the author Yu Jing, female, Han nationality, 24 years old, is a master’s student in the Textile Department of Xinjiang University. Subject major name: Textile Engineering. Research direction: Textile printing and dyeing process control. Contact number: 0991-4556976, 0991-8108106. E-mail:jingyu198049@163
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