sulphur dyes are dyes that are dissolved in alkali sulphur. They are mainly used for dyeing cotton fibers and can also be used for cotton/vitamin blended fabrics. The cost is low, the dye is generally able to wash and fast, but the color is not bright enough. Commonly used varieties are Sulphur Blue 7, Sulphur Red 14 Sulphur Black Bluishand so on. Soluble sulphur dyes are now available. A dye formed by the vulcanization reaction of amines, phenols, or nitro compounds of aromatic hydrocarbons with sulfur or sodium polysulphur,
peculiarity
sulphur dyes are insoluble in water, and sodium sulphur or other reducing agents are used to reduce the dyes to soluble leucochromes. It has affinity to the fiber and stains the fiber, and then restores its insoluble state by oxidation and fixation on the fiber. So sulphur dye is also a VAT dye. Vulcanized dyes can be used for dyeing cotton, hemp, viscose and other fibers, its manufacturing process is simple, low cost, can be dyed monochrome, but also can be mixed color, good fastness to sunlight, poor fastness to wear. Chromatographic lack of red, purple, darker color, suitable for dyeing strong color.
sort
According to the different dyeing conditions, sulfur dyes can be divided into sulfur dyes with sodium sulphur as reducing agent and sulfur VAT dyes with sodium disulfite as reducing agent. In order to use easily, the sulfonic acid group is substituted with sodium metabisulfite or sodium formaldehyde bisulfite (common name) to obtain water-soluble sulphur dye, which can be directly used for dyeing without reducing agent.
(1) sulfur dyes using sodium sulphur as a reducing agent;
(2) sulfur reduction dyes (also known as Haichang dyes) with insurance powder as a reducing agent;
(3) Liquid sulphur dye is a new type of sulphur dye developed and produced for convenient processing.
The use of such dyes is similar to soluble VAT dyes, which can be diluted directly with water in proportion to the configuration, without adding reducing agents, and some sodium sulphur should be added when only part of the color is light. This kind of dye chromatography is relatively broad, there are bright red, purple brown, Hu green.
Give birth to
There are two industrial production methods of sulfur dyes :① baking method, the raw material aromatic amines, phenols or nitro matter and sulfur or sodium polysulphur at high temperature baking, in order to produce yellow, orange, brown sulfur dyes. ② Boiling method, the amines, phenols or nitro substances of the raw aromatic hydrocarbons and sodium polysulphur are heated and boiled in water or organic solvents to obtain black, blue and green vulcanization dyeing.
nature
1, similar to direct dyes
(1) salt can be used to promote dyeing.
(2), cationic color fixing agent and metal salt color fixing agent to improve fastness.
2, similar to VAT dyes
(1), the dye needs to be reduced to leachite with a reducing agent to dye the fiber and oxidize on the fiber. Instead of a strong reducing agent, sodium sulphur is a weak reducing agent. However, the direct property of leaches to fibers after reduction is lower than that of VAT dyes, and the tendency of dye aggregation is greater.
(2) The reaction with acid can produce H2S gas, and the reaction with aluminum acetate can produce black aluminum sulphur precipitation.
3, higher temperature can be used to improve the diffusion rate of dyes and improve the degree of penetration.
Post time: Mar-01-2024