The use of reactive dyes for cellulosic fibers

Reactive dyes, due to their use of matrix dyes, linking groups, and reactive groups, enable them to form a strong covalent bond with the fibers when used, and have a series of other cellulose fiber dyes that are incomparable, establishing their use as fibers. The importance of the development and use of dyes for prime fibers is highlighted in the following four aspects:

(1) Reactive dyes are one of the best alternatives to banned dyes and other types of cellulose dyes such as sulfur dyes, ice dyes, and vat dyes.

(2) Reactive dyes can obtain high levels of fastness, especially wet fastness, using economical dyeing processes and simple dyeing operations.

(3) Reactive dyes have a wide spectrum of color, bright color, excellent performance, and strong applicability, and their hue and performance are basically compatible with the requirements of the market for fiber and clothing.

(4) Reactive dyes are suitable for printing and dyeing of new cellulosic fiber products such as Lyocell fiber.

However, the main technical problems of reactive dyes are as follows:

(1) The utilization rate is not high enough, generally 60% to 70%, resulting in Dali colored wastewater with a chromaticity exceeding several thousand times, COD values ​​generally ranging from 0.8 million to 30,000 ppm, and the COD value of concentrated wastewater exceeding 50,000 ppm. .

(2) In order to suppress the charge on the surface of the fiber, a considerable amount of electrolyte is consumed when the reactive dye is used, which not only increases the labor intensity, but also causes the concentration of chlorine ions in the waste water to be as high as more than 100,000 ppm, greatly increasing the activity of dyeing for reactive dyes. The difficulty of wastewater.

(3) Some of the color fastnesses can not meet the market requirements, such as the light fastness, wet rubbing fastness, and the light fastness of azo red dyes and azo blue dyes in light colors.

(4) There are fewer dark-colored species that can replace sulfided sulfides and also reverted dyes.