Basic knowledge of dyes: Classification of various dyes

2021/04/16

Guide:

1. Classified by chemical structure

2. Classified by application performance

3. Introduction to various dyes

4. Classification of disperse dyes





Basic knowledge of dyes: Classification of various dyes
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Basic knowledge of dyes: Classification of various dyes

 

#1. Classified by chemical structure

 

Divided into: azo dyes, anthraquinone dyes, arylmethane dyes, indigo dyes, sulfur dyes, phthalocyanine dyes, nitro and nitroso dyes, in addition to other structural types of dyes, such as methyl and polymethine dyes , Stilbene dyes and various heterocyclic dyes, etc.

 

#2. Classification by application performance

 

Divided into: direct dyes, acid dyes, cationic dyes, reactive dyes, insoluble azo dyes, disperse dyes, vat dyes, sulfur dyes, polycondensation dyes, fluorescent brighteners, in addition, there are oxidation dyes used in textiles (such as aniline black ), solvent dyes, polypropylene dyes and food colorings for food.

 

#3. Introduction to various dyes

 

Dye name

Structural properties

Dyeing objects and methods

Direct dye

Direct dyes are a type of water-soluble anionic dyes. Most of the dye molecules contain sulfonic acid groups, and some have carboxyl groups. The dye molecules and cellulose molecules are combined by van der Waals forces and hydrogen bonds.

Direct dyes are mainly used for dyeing cellulose fibers, but also for dyeing silk, paper, and leather. During dyeing, the dye is directly dyed on the fiber in the dye liquor, and is adsorbed on the fiber through van der Waals force and hydrogen bond.

Acid Dyestuff

Acid dyes are a type of water-soluble anionic dyes. The dye molecule contains acidic groups such as sulfonic acid group and carboxyl group, which usually exists in the form of sodium salt. In the acid dye bath, it can bond with the amino group in the protein fiber molecule by ionic bond, so it is called acid dye.

It is commonly used for dyeing silk, wool and polyamide fibers and leather. Acid dyes dye fibers through their own affinity and bind to fibers with ionic bonds; acid mordant dyes have similar dyeing conditions to acid dyes, but they need to form a chelate compound on the fiber through the action of certain metal salts to obtain good results. Washing resistance; acid mordant dyes, some acid dyes have chelated metal ions in their molecules, have low hydrolysis tendency and good dye fastness.

 

Cationic dyes

Cationic dyes are soluble in water and are in a cationic state. Early dyes contained basic groups such as amino groups in their molecules, often in the form of acid salts.

It is mainly used for the dyeing of polyacrylonitrile fibers, which can be combined with the carboxyl anions in the molecules of protein fibers such as silk in the form of salt bonds.

 

Reactive dyes

Reactive dyes are also called reactive dyes. The molecular structure of this type of dye contains active groups, which can covalently bond with the hydroxyl and amino groups in the fiber molecule during dyeing to firmly dye the fiber.

Reactive dyes are mainly used for dyeing and printing of cellulose fiber textiles, as well as for dyeing wool and nylon fibers. The dye dyes the fiber through its own affinity, and then firmly binds to the fiber through a covalent bond under the action of the alkali agent.

 

Insoluble azo dyes

In the dyeing process, the diazo component (color base) and the coupling component (chromanol) directly react on the fiber to produce insoluble lake and dye. This kind of dye is called insoluble azo dye.

This type of dye is mainly used for dyeing and printing of cellulose fibers. The color base is first diazotized, and then dyed to the fiber fabric backed by naphthol through affinity, and then coupled to form an insoluble lake to be firmly stored on the fabric.

Disperse Dyes

Disperse dyes are a kind of non-ionic dyes with simple structure and extremely low water solubility. They mainly exist as dispersions of tiny particles in the dye bath. The chemical structure of disperse dyes is mainly based on azo and anthraquinones, and there are also heterocyclic disperse dyes.

Disperse dyes are mainly used for dyeing and printing of polyester fibers, as well as for dyeing acetate fibers and polyamide fibers. When dyeing, the dye must be evenly dispersed in the dye liquor with the help of a dispersant, and then various synthetic fibers are dyed.

 Vat Dyes

Vat dyes are mostly polycyclic aromatic compounds, and their molecular structure does not contain water-soluble groups such as sulfonic acid groups and carboxylic acid groups. Their basic feature is that they contain two or more carbonyl groups in the conjugated double bond system of the molecule, so they can reduce the carbonyl group to a hydroxyl group under the action of sodium hydroxide, and become a soluble hidden in the alkaline aqueous solution. Sodium salt of chromosome.

 

Vat dyes are mainly used for dyeing cellulose fibers. During dyeing, they are reduced to water-soluble leuco sodium salt in an alkaline solution containing a reducing agent (such as Na2S2O4, sodium dithionite, commonly known as sodium sulfite) and dye the fiber, and then become an insoluble dye again after being oxidized. Fix to the fiber.

 

Sulfur Dyes

Sulfur dyes are a type of water-insoluble dyes, which are generally prepared by mixing aromatic amines or phenolic compounds with sulfur or sodium polysulfide by heating. This process is called vulcanization.

Sulfur dyes are mainly used for dyeing cellulose fibers. During dyeing, they are reduced to a soluble state in the alkali sulfide solution. After dyeing the fiber, it becomes insoluble and fixed on the fiber after oxidation.

 

Condensation Dyes

Condensation dyes are dyes that can covalently bond between molecules of the dye itself or with compounds other than fibers during or after dyeing, thereby increasing the molecules. The polycondensation dye molecule contains thiosulfuric acid group (-SSO3Na). Under the action of sodium sulfide, sodium polysulfide, etc., the sulfite group can be shed from the thiosulfuric acid group and form -S-S between the dye molecules. -Bond, which makes two or more dye molecules bind into an insoluble state and fixed on the fiber.

Polycondensation dyes are soluble in water, they can remove water-soluble groups on the fiber and undergo intermolecular polycondensation reaction, becoming insoluble dyes with relatively large molecular weight and fixed on the fiber. At present, such dyes are mainly used for dyeing and printing of cellulose fibers, and can also be used for dyeing of vinylon.

Fluorescent Brightener

Fluorescent brighteners can be regarded as a kind of colorless dyes. After they are dyed on fiber, paper and other substrates, they can absorb ultraviolet rays and emit blue light, thereby offsetting the yellowness caused by excessive yellow light reflection on the fabric. Visually produce white and dazzling effects.

Different types of fluorescent whitening agents can be used for the whitening treatment of various fibers. They are directly processed on the fabric and fixed on the fiber by their own affinity or cross-linking agent.

 

#4. the classification of disperse dyes

 

4.1 Classified by molecular structure:

 

According to the molecular structure, it can be divided into three types: azo type, anthraquinone type, and heterocyclic type. Among them, the azo type is the main type, and the azo type is further divided into single azo type and double azo type.

 

 

category

The proportion

Detailed

Monoazo

More than 50% of disperse dyes

The molecular weight is generally 350-500, the manufacturing process is simple, the cost is relatively low, the chromatogram is complete, the leveling property is excellent, the lifting power is high, and the color fastness varies greatly due to different structures. Light, medium and dark color series are available. Such as disperse blue H-GL (C.I.disperse blue 79), disperse red jade S-2GFL ((C.I.disperse Red 167), disperse red jade SE-GL((C.I.disperse Red 73)

Bisazo

About 10% of disperse dyes

The chromatogram is mainly in medium and dark colors, and the chromatogram is mainly in orange, yellow and dark blue. The manufacturing process is more complicated, the cost is relatively high, the dyeing performance is average, and the color fastness is average. Such as disperse yellow E-RGFL (C.I.disperse Yellow 23), disperse orange SE-GL (C.I.disperse Orange 29)

Anthraquinone

About 25% of disperse dyes

The color is bright, the color spectrum is mainly red, purple, blue, etc., with good levelling performance and excellent light fastness. The synthesis process is long, expensive, and excellent in dyeing performance, but generally the lifting power is not good, the color fastness is good on the whole, the structure is different, and the color fastness difference is also large. Such as Disperse Red E-3B (C.I.disperse Red 60), Disperse Blue 2BLN (C.I.disperse Blue 56), Disperse Turquoise Blue S-GL (C.I.disperse Blue 60)

Heterocycle

Less than 15% of disperse dyes

The chromatogram is relatively complete, the shade is brighter, some varieties are fluorescent, the color intensity is high, the manufacturing process is complicated, the cost is high, the dyeing performance is good, and the color fastness performance is better. Such as disperse yellow E-3G (C.I.disperse Yellow 54), disperse red CBN (C.I.disperse Red 356).

 

4.2 Classified by application performance

 

Dyestuff classification/characteristics

High temperature type S

Medium temperature type SE

Low temperature type E

Dye molecule size

Large

Medium

Small

Sublimation fastness

High

Medium

Medium or Low

Level dyeing

Poor

Medium

Good

Hot melt dyeing and fixing temperature

200-220℃

190-205 ℃

180-195℃

Carrier dyeing at 100℃

Generally not used

Available

Be applicable

Printing

Partially suitable

Partially suitable

Inappropriate

4.3 Other classification methods

 

There are also some foreign dye manufacturers according to the sublimation fastness of dyes into three types: H, M, and E, which correspond to the above-mentioned S, SE, and E types respectively. Such as disperse blue H-GL (C.I. disperse blue 79), disperse red H-2GL (C.I. disperse red 167), and disperse blue M-2R (C.I. disperse blue 183).

 

The Dispersol series of disperse dyes from the British Empire Chemical Company (ICI) are divided into five categories: Class A has low sublimation fastness, mainly acetate and polyamide fibers; Class B, C, and D are suitable for polyester fibers (equivalent to E, SE, respectively) , S three types), P type is dedicated to printing. Such as Dispersol Scarlet A-B, Dispersol Blue B-R, Dispersol Green C-6B, Dispersol Brilliant Scarlet D-SF, Dispersol Red P-4G.

 

The Kayalon Polyester series disperse dyes of Nippon Kayaku Co., Ltd. (KYK) are divided into four categories according to the sublimation fastness and dyeing performance of disperse dyes: S, SF, SE, E; according to the sublimation fastness and light fastness, they are divided into four categories. Divided into four categories: LS, L-SF, L-SE, LE. Such as Kayalon Polyester Orange R-SF, Kayalon Polyester pink RCL-E, Kayalon Polyester rubine BL-S, Kayalon Polyester Turquoise blue GL-S, Kayalon Polyester blue FBL-E, Kayalon Polyester yellow YL-SE, Kayalon Polyester red TL-SF .

 

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