Dyes are compounds that, in certain media, can strongly color fibers or other substances. The dyes and pigments we introduce are limited to organic compounds. Ancient dyes take automatic plants. In 1856 Perkin invented the first synthetic dye, horsetail violet, which separated organic chemistry into a new discipline, dye chemistry. 1950s. Pattee and Stephen found that the dyes containing dichloro-s-triazine groups were bonded to the hydroxyl groups on the fibers under alkaline conditions, which marked that the dyes changed the color of the fibers from the physical process to the chemical process, creating a period of synthetic application of reactive dyes. . At present, dyes are not limited to the dyeing and printing of textiles. They are used in many sectors such as paint, plastics, paper, leather, optoelectronics, and food.
Classification of dyes There are three classification methods for dyes: by source (natural and synthetic dyes), by application performance, and by chemical structure. Commonly used after the two classification methods.
Dyes are classified into the following categories based on application performance:
1. direct dyes
The dyes and fiber molecules have a combination of van der Waals forces and hydrogen bonds. The molecules contain sulfonic acid groups and carboxyl groups and are soluble in water. They exist in water as anions and can dye fibers directly.
2. Acid dyes
In acidic media, the sulfonic acid groups, carboxyl groups contained in the dye molecules and the amino groups in the protein fiber molecules are ionically bonded and are mainly used for the dyeing of protein fibers (wool, silk, leather).
3. Disperse Dyes (disperse dyes) These types of dyes have a low water solubility and are dyed with a dispersant in a dispersed state to dye hydrophobic fibers (polyester, nylon, etc.).
4.Reaction dyes
There is a group in the dye molecule that can chemically react with the hydroxyl and amino groups of the fiber molecule. The fibers are colored by forming covalent bonds with the fibers. Also known as reactive dyes. It is mainly used for the dyeing of cotton, hemp, synthetic fibers, and also for the coloration of protein fibers.
5. vat dyes
There are two kinds of insoluble and soluble in water. Insoluble dyes are reduced to soluble in alkaline solutions, which are then oxidized to restore their insolubility on the fibers and color the fibers. Solubility eliminates the need for a reduction step. This type of dye is mainly used for the dyeing and printing of cellulose fibers.
6. The cationic dyes are named after being cationic in water. For the dyeing of acrylic fibers, it is often incorporated into basic dyes.
7. Azoic dyes
For insoluble azo dyes, dyeing is performed under freezing conditions (0-5°C), and diazo and dimeric components react directly on the fibers to form precipitates and stain.
8. Polycondesation dyes
When dyes of this type are dyed, water-soluble groups are dehydrated and macromolecular insoluble dyes are attached to fibers, which are called polycondensation dyeing.
In addition there are oxidation dyes, * dyes and so on.
Classified by chemical structure (mainly based on the structure of the conjugate system contained in the dye). Can be divided into: azo, phthalocyanine, anthraquinone, cyanine, steroids, aromatic methane, nitro and nitroso dyes. In some large categories, there are several subcategories.
In fact, it is difficult for some dyes to be categorized only by their structure and performance. The above two classification methods need to be further improved.
The dyes named dyes have complex molecular structures. Manufacturers often use a dye with multiple product names for their own benefit. System names and trade names are more complicated for dyes. All countries have their own unified nomenclature for dyes.
The nomenclature of dyes in our country, simply speaking, the dye name can be composed of three sections. The first paragraph is crowned and there are 31 species that indicate the method of dyeing and performance. The second paragraph is color, there are 30 color names that indicate the basic color of the dye. The third paragraph is the suffix, with the Latin letters or symbols representing the shade, morphology and special properties and uses of the dye. For example, reactive brilliant red X-3B dye: "activity" is the crown, "bright red" is the color scale, X-3B is the end of the word, X is the high concentration, and 3B is the blue color slightly darker than 2B. It is indicated that this dye is a highly concentrated brilliant red dye with blue light.
Chinese dye naming word
1 Crown is direct, direct light, direct copper blue, direct diazo, acidic, weakly acidic, acidic complex, acidic media, neutral, cation, activity, reduction, soluble reduction, dispersion, *, chromophore, color Phenol, color blue, soluble *, fast pigment, oxidation, polycondensation, blending and so on.
2 colors called yellow, yellow, golden, dark yellow, orange, red, red, pink, rose, magenta, red purple, red, purple, blue, blue, blue, dark blue, green, brilliant green, dark Green, yellow brown, red brown, brown, dark brown, olive green, grass green, gray, black and so on.
3-color light
B - with blue or blue light; G - with yellow or green light; R - with red light
4 color light quality
F- indicates pure light; D- indicates dark or slightly dark; T- indicates dark
5 nature and use
C-chlorine resistant, cotton
I - the fastness of Shihlin vat dyes;
K-cold dye (Chinese reactive dye K represents thermal dyeing)
L-fastness or good dyeing
M-mixture;
N-new or standard;
P-applicable to printing;
X-high concentration (Chinese reactive dye X represents cold dyeing).
The dye crowns in various countries are basically the same, and the color names and suffixes are somewhat different, and often vary from manufacturer to manufacturer. China will adopt a unified nomenclature as needed.
Dye products synthesized by commercial dyes are generally not directly used for dyeing. After mixing and grinding, a certain amount of fillers and additives are added to process into commercial dyes. This standardization process calls the commercialization of dyes.
Different dyes have different requirements for appearance, fineness, moisture, pH, strength, shade, fastness, solubility, and diffusion properties, and their commercialization process is also different.
Dye particle size and uniformity, have a certain influence on the dyeing properties. In order to ensure the quality of printing and dyeing, some dyes should be sanded, and dispersants and wetting agents should be added during grinding to achieve a certain degree of dispersion.
Chromatic light is an important quality of the dye, and processing and mixing methods are adopted to eliminate the difference in color light of each batch of raw materials to obtain a stable color dye.
The amount of dye often depends on its strength. The dyestuffs have high intensity, high dyeing power and strong color. On the contrary, they have low dyeing power and light color. To obtain the same color, the amount of dye with high intensity is relatively less.
The commercialization of dyes is processed to achieve a certain dyeing effect. Often add some additives in the dye, such as diluents, wetting agents, diffusing agents, stabilizers, solubilizers, water softeners, etc.
Basic Properties of Domestic Reactive Dyes and Their Effects on Printing Properties--《Printing & Dying》1979年03期
<Positive> There are four types of domestic reactive dyes: X-type, K-type, M-type, and KN-type. They are widely used in the printing of cotton fabrics and polyester-cotton fabrics, and have accumulated a certain amount of application experience for many years. But generally use the bath printing process. The basic characteristics of domestic reactive dyes (such as directness, diffusibility, chemical reactivity, etc.), and the relationship between printing properties in particular, have not been systematically studied. In order to explore its internal relations, we systematically tested the basic characteristics of more than 30 reactive dyes made in China, as well as the printing performance of each dye (including alkalis, urea, and anti-stain salt S; 40 hours after the paste was stored). The effect of steaming and printing on the amount of color after steaming for 1 hour.) The name and meaning of the system's small sample dye are many. Each dye has a chemical name according to its chemical structure. However, most dyes are organic compounds with complex structures. If they are named according to their organic structures, the name is very complicated, and the color and application properties of dyes cannot be reflected at the same time. Therefore, the name of the chemical structure of dyes is not suitable for practical applications. It is best to give the appropriate name in combination with the application properties of the dye.
Domestically produced commercial dyes, the naming consists of three parts:
a The type of dye, b the color of the dye, and c indicate the color, properties, state, concentration, purity, etc. of the dye. For example, Acid Green B, "Acid" indicates the category to which the dye belongs, "Green" indicates the basic color of the dye, and "B" indicates that the dye has blue light.
Common symbols and their meanings are listed below:
B indicates blue light or blue light.
C indicates that it is suitable for dyeing cotton.
D is for dyeing.
E indicates that it is suitable for dip dyeing.
Ex indicates high concentration.
F indicates good dye fastness or fine dye particles.
G stands for yellow light or green light.
H indicates that it is suitable for the dyeing of cotton wool fabrics.
J means yellow light.
K is for cold dyeing (reducing dyes), or for thermosetting reactive dyes.
L indicates light or light resistance, or good solubility, or good levelness.
N means normal and standard meaning, or a new dye.
O means orange light or high concentration.
P indicates that it is suitable for printing or dyeing, or indicating powdered dyes.
R indicates red light.
S is water soluble or suitable for dyeing silk.
V stands for violet light.
W indicates that it is suitable for dyeing wool.
X means that the concentration is extremely high.
Y means with yellow light.
There are often percentages in the dye name. It is the strength of the dye, such as 100%, 200%, etc. The so-called dye strength means that the dye factory chooses a certain concentration of dye as the standard, and compares each batch of product with it. For example, 50% means that a certain dye's strength is half that of a standard dye. However, dye factories often add fillers such as accelerators, diffusing agents, co-solvents and other additives in the dyes, and care should be taken when using them.