Basic Knowledge of Dyes: Reactive Dyes

Brief introduction of reactive dyes

As early as more than a century ago, people hoped to produce dyes that can form covalent bonds with fibers, thereby improving the washfastness of dyed fabrics. Until 1954, Raitee and Stephen of Bnemen Company found that dyes containing dichloro-s-triazine group can covalently bond with primary hydroxyl groups on cellulose under alkaline conditions Together, and then dyed firmly on the fiber, there is a class of reactive dyes that can form covalent bonds with the fiber through chemical reaction, also known as reactive dyes. The emergence of reactive dyes has opened a brand new page for the development history of dyes.

Since the advent of reactive dyes in 1956, its development has been in a leading position. At present, the annual output of reactive dyes for cellulose fibers in the world accounts for more than 20% of the annual output of all dyes. Reactive dyeing can develop rapidly because of the following characteristics:

1. The dye can react with the fiber to form a covalent bond. Under normal conditions, such a bond will not dissociate, so once the reactive dye is dyed on the fiber, it has good dyeing fastness, especially wet treatment . In addition, after dyeing the fiber, it will not suffer from light embrittlement like some vat dyes.

2. It has excellent leveling performance, bright color, good brightness, convenient use, complete chromatography, and low cost.

3. It can already be mass-produced in China and can fully meet the needs of the printing and dyeing industry; its wide range of use can be used not only for the dyeing of cellulose fibers, but also for the dyeing of protein fibers and some blended fabrics.

History of reactive dyes

Since the 1920s, Ciba has started research on cyanuric dyes, which have better performance than all direct dyes, especially Chloratine Fast Blue 8G. It is a combination of an inner molecule composed of a blue dye containing an amine group and a yellow dye with a cyanuric ring into a green tone, that is, the dye has an unsubstituted chlorine atom, and under certain conditions, it can The element reaction formed a covalent bond, but it was not recognized at the time.

In 1923, Ciba found that acid monochlorotriazine dyes dyed wool, which can obtain high wet fastness, so in 1953 invented Cibalan Brill type dye. At the same time, in 1952, Hearst also produced Remalan, a reactive dye for wool, on the basis of studying vinyl sulfone groups. But these two types of dyes were not very successful at the time. In 1956 Bu Neimen finally produced the first commercial reactive dye for cotton, called Procion, which is now the dichloro-triazine dye.

In 1957, Benemen developed another monochlorotriazine reactive dye, called Procion H.

In 1958, Hearst Corporation successfully used vinyl sulfone-based reactive dyes for dyeing cellulose fibers, known as Remazol dyes.

In 1959, Sandoz and Cargill officially produced another reactive group dye, namely trichloropyrimidine. In 1971, on this basis, a better performance of difluorochloropyrimidine reactive dyes was developed. In 1966, Ciba developed a reactive dye based on a-bromoacrylamide, which has good performance in wool dyeing, which laid the foundation for the use of high-fastness dyes on wool in the future.

In 1972 in Baidu, Benemen developed a dye with dual reactive groups, namely Procion HE, on the basis of monochlorotriazine type reactive dye. This type of dye has further improved in terms of its reactivity with cotton fibers, fixation rate and other properties.

In 1976, Buneimen produced a class of dyes with phosphonic acid groups as the active group. It can form a covalent bond with cellulose fibers under non-alkali conditions, especially suitable for dyeing with disperse dyes in the same bath The same paste printing, the trade name is Pushian T. In 1980, based on the vinyl sulfone Sumifix dye, Sumitomo Corporation of Japan developed vinyl sulfone and monochlorotriazine double reactive group dyes.

In 1984, Nippon Kayaku Corporation developed a reactive dye called Kayasalon, which added a nicotinic acid substituent to the triazine ring. It can covalently react with cellulose fibers under high temperature and neutral conditions, so it is especially suitable for dyeing polyester / cotton blended fabrics with high temperature and high pressure one bath dyeing method for disperse / reactive dyes.

Reactive Dyeing

Structure of reactive dyes

Reactive dyeing supplier believes that the biggest difference between reactive dyes and other types of dyes is that their molecules contain reactive groups that can covalently bond with certain groups of fiber (hydroxyl, amino) through chemical reaction Called reactive group). The structure of reactive dyes can be expressed by the following general formula: S－D－B－Re

In the formula: S-water-soluble group, such as sulfonic acid group;

D——Dye matrix;

B——The linking group between the parent dye and the active group;

Re-active group.

In general, the application of reactive dyes on textile fibers should have at least the following conditions:

High water solubility, high storage stability, not easy to hydrolyze;

It has high reactivity to fiber and high fixing rate;

The chemical bond between the dye and the fiber has high chemical stability, that is, the bond is not easy to fade during use;

Good diffusibility, good level dyeing and good dye penetration;

Various dyeing fastness, such as sunlight, climate, washing, rubbing, chlorine bleaching resistance, etc. are good;

Unreacted dyes and hydrolyzed dyes are easy to wash off after dyeing, without staining;

Dyeing is good, it can be dyed deep and dark;

The above conditions are closely related to reactive groups, dye precursors, water-soluble groups, etc. Among them, reactive groups are the core of reactive dyes, which reflect the main categories and properties of reactive dyes.