Dyestuffsare a class of organic compounds that can give other substances bright and firm color. But colored substances are not necessarily dyes. The dye must be able to attach a certain color to the fiber, and it is not easy to fall off and change color.
Dyes are usually soluble in water, and some of the dyes require mordants to make the dyes adhere to the fiber. Dyes are generally composed of chromophore and auxiliary chromophore.
Pigment refers to the insoluble (insoluble in water, organic solvent, color developing agent and colored substance) that can make the substance colored.
Dyestuffs Categories
1. According to the properties and applications, they can be divided into direct dyes, acid dyes, cationic dyes, reactive dyes, insoluble azo dyes, disperse dyes, vat dyes, sulfide dyes, Polycondensation dyes, fluorescent brighteners, in addition, there are oxidation dyes for textiles (such as aniline black), solvent dyes, polypropylene dyes and edible pigment.
2. According to the dyeing method, dyes can be divided into direct dyes, acid dyes, basic dyes, acid mordant dyes, vat dyes, insoluble azo dyes, disperse dyes, reactive dyes, oxide dyes and so on.
3. According to the chemical structure or characteristic groups of dyes, dyes can be divided into azo dyes, anthraquinone dyes, arylmethane dyes, indigo dyes, sulfide dyes, phthalocyanine dyes, nitro and nitroso dyes, as well as other structural types of dyes, such as methylene and polymethylchuan dyes, stilbene dyes and various heterocyclic dyes.
4. According to the solubility, they can be divided into Acid dyes, Basic dyes, Mordant dyes, Vat dyes, Reactive dyes, disperse dyes, Sulfur dyes and son on.
5. They can also be divided into natural dyes and synthetic dyes.
Natural dyes are obtained from plants, animals or mineral resources, without artificial synthesis, with little or no chemical processing.
Synthetic dyes, also known as artificial dyes, are mainly fractionated from coal tar (or petroleum processing) through chemical processing, commonly known as "coal tar dyes". Synthetic dyes are sometimes called "aniline dyes" because they mainly use aniline as raw material in the early stage of development. And they are commonly used in the fields of textiles, paints and printing.
The difference between natural dyes and synthetic dyes is that synthetic dyes are chemically manufactured, while natural dyes are pure natural, and the price of natural dyes is much more expensive than synthetic dyes, so most of the dyes used in industry are synthetic dyes'.
Pigments Categories
Pigments exhibit a classification predicated on their chemical composition, segregating them into two categories: inorganic pigments and organic pigments. Moreover, their origin delineates a distinction between natural pigments and synthetic pigments.
Natural pigments are derived from botanical, faunal, or mineral sources and typically remain untampered by synthetic processes, retaining their essence in its unprocessed state. Contrariwise, synthetic pigments are meticulously engineered through chemical synthesis.
Within this spectrum, inorganic pigments such as titanium dioxide, zinc barium white, lead chrome yellow, and iron blue stand as exemplars. Likewise, organic pigments like red powder, even light yellow, phthalocyanine blue, and quinacridone resonate with this synthetic paradigm, reflective of their origin through synthetic routes.
Organic pigments have bright colors, bright tones, wide chromatographic range and many varieties. They have much higher coloring power or coloring strength than inorganic pigments, and some varieties also have high transparency. Suitable for fabric printing, plastics, rubber, ink and high-grade paint coloring.
Most of the colors of inorganic pigments are dark, not bright enough, the variety is too few, the chromatography is not complete, and many inorganic pigments are toxic. However, the production of inorganic pigments is relatively simple and cheap, so the current output of inorganic pigments is much higher than that of organic pigments.
Pigments are suitable for plastics, glass, ceramics, enamel, coatings and other industries. In addition to bright colors, in terms of physical properties, it also has good covering power, coloring power, dispersion, oil absorption, light resistance, etc.
Dyes and pigments, both delicate hued materials, present discernible disparities in their characteristics. Notably, dyes exhibit a vibrancy of color surpassing that of pigments. However, this heightened chromatic brilliance comes at a cost—dyes lack the tenacity in coloring prowess, coverage efficiency, and resilience against light and moisture that pigments inherently possess.
The process of pigmentation doesn't entail any form of chemical amalgamation between the molecules of dyes and those of pigments. Additionally, pigments are notably insoluble in water and other solvents, evading any form of dissolution. This contrasts vividly with dyes, where a chemical liaison forms between dye molecules and pigment molecules, inducing a selective tinting effect on objects. Furthermore, this interaction renders dyes soluble in water as well as organic solvents.
While dyes flourish in the realm of exuberance, pigments take the lead in endurance, versatility, and permanence, collectively contributing to the rich spectrum of color expression.
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