Reconstituted dyes are organic compounds that are insoluble in water, although they have different chemical structures and colors but they have the same property, that is, they all contain ketone groups in the molecule and have The general form is: R = C = O. When dissolved, this insoluble form will change back to an acidic form, which is insoluble in water but soluble in alkali and transformed into a basic contaminant. Due to its great affinity for fiber and water solubility, it is strongly adsorbed on cellulosic fibers, on the other hand, it is easily hydrolyzed and oxidized to its original insoluble form. The whole process is as follows:
Because of its affinity for cellulosic fibers, the basic infusion compound begins to strongly attach to the fibers, and then, when washed off the alkaline, it is easy to hydrolyze to the non-communicable form of acid and oxidize with the oxygen of the air to the original insoluble form.
Dyes of all colors, bright colors, high color fastness with wet processing of light and atmosphere; Only color fastness to friction is not very high. They have a high color fastness with many indicators on one hand because when they are on the fiber in insoluble form, on the other hand, because their molecule is rich in aroma, it is able to generate strong bonding.
Reconstituted dyes are mainly used for dyeing cellulosic preparations or cellulosic components in blended fabrics. They are not used to dye wool and silk because the dyeing process must be conducted in an alkaline environment, these fibers will be destroyed. A few reconstituted dyes are also used as disperse dyes (finely soluble forms) to dye synthetic fibers or to make flower-printing pigment.
The technological process is difficult, complicated, difficult to uniformly color, in order to achieve a high uniformity, control over many specifications is required.
Conventional dyes come in 3 groups:
220.127.116.11 Indigoite reconstituted dye:
• Plant Indigo:
To dye the dark blue from centuries ago, it was known to use plant indigo separated from indigo and some plants of this family.
The main constituent of the pigment contained in indigo species is Indican, which is a glucoside derivative of indoxin. To separate indigo from stems and leaves of indigo, it is often used microbiological method in the form of composting for fermentation. When annealed under the effect of yeast, indican will be hydrolyzed to form indoxine and glucosane. Under the effect of air oxygen, indoxin will turn into indigo as follows
+ H2O + C6H11O5
• Indigo synthesizes and its derivatives:
After finding the chemical formula of indigo, it has been synthesized by many different methods, but because indigo has only one dark blue, to expand the gamut, they have synthesized indigo derivatives or called indigoit. By introducing different substituents into the indigo molecule, different colors are obtained. Indigo T is greenish blue, bromindigo is purple red.
All reconstituted dyes that are derivatives of indigo have a common property that is more easily reduced than multidiscipline dyes. Their dye solutions also require lower alkalinity concentrations than the polycyclic dye.
18.104.22.168 Multi-cyclic dye:
Polycyclic reconstitution is a complex molecular structure dye containing many aromatic nuclei, many cyclic groups, most of which are antra quinone derivatives.
In contrast to the reconstituted dye, which is a derivative of indigo, dyes of this subgroup require stronger reducing conditions, dyeing in a more alkaline environment and less stable leucobazo solution, prone to hydrolysis and oxidation. to a more insoluble form.
Multi-cycle reconstituted drug has all colors, fresh color, high color fastness with wet and light processing, particularly color fastness to friction is not very high. According to the chemical structure of cyclic reconstituted medicine divided into groups:
• The dye is a derivative of oxylaminoantraquinon.
The color of this dye ranges from yellow to purple. When used, it should be noted that at high temperatures and alkalinity, the acetyl group may be saponified, causing the dye to degenerate.
• Dyes are derivatives of antrimit (antraquinonimin)
These dyes in their molecule contain two or more young antra-radicals, linked together by imin group (- NH-). Algol bocdo RT is one of the typical dyes of this group, having the following formula:
Because the molecule contains two chlorine atoms, its color is deeper and more durable to light than chlorine-free derivatives.
• Reconstituted dyes are derivatives of inantron:
This group of dyes contains antraquinone nuclei linked together through two imim groups to form a closed loop, typically the RSN blue reconstituted formula in two forms:
This dye is bright blue, but it is easy to get rid of it, so when you prepare the dye, you need to remove the following amount of reducing agent so that only two groups of ketones are reduced and converted to the form of disodium salt in the solution.
• Reconstituted dyes are derivatives of antantron:
Some antantron derivatives are used as vat dyes, their molecules can be thought of as two assembled antraquinone nuclei. Most of them are precious dyes, yes