The similarities and differences between organic pigments and dyes, inorganic pigments briefly2016.03.17 10:43
As is known to all, colorants basic divided into organic pigments and dyes, inorganic pigments, organic pigments has been developing rapidly recently. With the other two kinds of colorants what are the similarities and differences?
The differences between organic pigment and dye
Organic pigment and dye are colored organic compounds, from the perspective of the chemical structure of organic pigments and dyes, both are very similar, even some organic compounds can be used as a dye and can be used as organic pigment, but organic pigment and dye is two different concepts, application performance difference between them is different. The traditional use of dye is to dyeing of textiles, and the traditional use of pigment is of textiles (such as ink, paint, coatings, plastics, rubber, etc.) staining. Textiles have an affinity for this is because the dye (or direct), can be fiber molecular adsorption, sessile; On all paint color objects are no affinity, mainly by resin, adhesives and other film forming material and color objects together. Dye in the process of using soluble in first commonly used medium, even disperse dye and VAT dye, also experienced a when dyeing from crystal soluble in water first become molecular state after dyeing on the fiber process. As a result, the color of the dye itself doesn't mean it in the color of the fabric. Pigments in use process, due to insoluble in working medium, so always exist in the original state of crystal. Therefore, the color of the paint itself represents its color in the substrate. Because of this, of a crystallization of the pigment for paints is very important, and of a crystallization of the dye is less important, or of a crystallization of the dye itself is not close relationship with its dyeing behavior.
Pigments and dyes are different concepts, but in certain cases, they can general again. For example some anthraquinones VAT dye, they are insoluble dyes, but after also can be used as a pigment. This kind of dye, called pigment dyes, pigment or dye.
The differences between organic pigments and inorganic pigments
Compared with inorganic pigments, organic pigments have many unique advantages. By changing the molecular structure of organic pigments can be prepared in a wide range of varieties, and have more vivid colors than inorganic pigment, more bright colors. Organic pigment also has a much higher than inorganic pigment tinting strength, can be prepared high tinting strength, high transparency of varieties, to meet the requirements of high-grade coatings and printing ink. Most of the varieties of organic pigment less toxicity, and most of the inorganic pigments containing heavy metals, such as chrome yellow, red lead, scarlet, etc all have certain toxicity. Low-grade varieties of organic pigment in sun fastness, weathering resistance, heat resistance and solvent resistance to various aspects, such as inferior to inorganic pigments, but some high-grade organic pigment varieties (such as: quetiapine acridone pigments, phthalocyanine pigment, etc.) are excellent sun fastness, weathering resistance, heat resistance and solvent resistance, and acid/alkali can also better than the inorganic pigment, because of some inorganic pigment acid/alkali can lower, such as: will get black, chrome yellow in the hydrogen sulfide in alkali will turn red; Ultramarine blue easily by acid decomposition. Organic pigments varieties, types, production and application range are growing and expanding, has become a kind of important fine chemical products.