Advantage
Reactive dyes are composed of parent dyes, linking groups and reactive groups, which enable them to form a firm covalent bond with fibers during use, and have a series of incomparable characteristics with other cellulose fiber dyes, establishing their use as fibers The key status of the development and use of dyestuffs for plain fibers is prominently embodied in the following four aspects:
(1) Reactive dyes are one of the best choices to replace prohibited dyes and other types of cellulose dyes such as sulfur dyes, ice dyes and vat dyes.
(2) Reactive dyes can use economical dyeing technology and simple dyeing operations to obtain high levels of various fastness properties, especially wet fastness.
(3) Reactive dyes have wide chromatograms, bright colors, excellent performance and strong applicability, and their hue and performance are basically in line with the market's requirements for fibers and clothing.
(4) Reactive dyes are suitable for printing and dyeing of new cellulosic fiber products such as Lyocell fiber.
Disadvantage
But the main technical problems of reactive dyes are as follows:
(1) The utilization rate is not high enough, generally 60%~70%, which produces a large amount of colored sewage, the chroma of which exceeds several thousand times, the COD value is generally 8,000 to 30,000 ppm, and the COD value of concentrated wastewater exceeds 50,000 ppm. .
(2) In order to suppress the charge on the surface of the fiber, a considerable amount of electrolyte is consumed when using reactive dyes, which not only increases labor intensity, but also causes the chloride ion concentration in the wastewater to reach more than 100,000 ppm, which greatly increases the treatment of reactive dyes. Difficulty of wastewater.
(3) Certain color fastnesses cannot meet market requirements, such as light fastness to perspiration, wet rubbing fastness, and light fastness of azo red dyes and azo blue dyes in light colors.
(4) There are fewer dark varieties that can replace vulcanizates and vat dyes.