What are the differences between plastic colorant dyes and pigments? What are the features?

A substance that can change the color of an object, or that can color an otherwise colorless object, commonly referred to as a colorant. Colorants produce colors by selectively absorbing and reflecting some light from the colored light wave. Traditionally, plastic colorants can be divided into dyes and pigments in two categories
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., what is dye? What is pigment? What is the difference between dyes and pigments?are organic compounds that are soluble in most solvents and dyed media. It is characterized by good transparency in plastics, strong coloring force, relative density is small, generally suitable for transparent plastic coloring, but dye heat resistance, poor light resistance, color migration tendency. Pigments and dyes are different, pigments are insoluble in water, oil, resin and other media of colored substances, usually in a dispersed state in the plastic, so that these products show different colors.
instead of dyes, pigments can have no affinity with the material they are coloring, so for ideal coloring performance, it is necessary to distribute the pigment evenly among the plastics by mechanical means. Dyes are characterized by good transparency, high coloring strength and low density, generally suitable for transparent plastic coloring, organic pigments are the main pigment varieties, commonly used in vane (blue, green), acetic nitrogen (yellow, green, red, orange) and ketones (red, purple). Organic pigment color bright, has a good brightness, but the brightness is not as bright as dyes, heat resistance is better than dyes, its relative density is small, high oil absorption value. Inorganic pigments are usually natural or synthetic metal oxides, sulphides, and other salts calcined at high temperatures. It has relative density, low oil absorption value, cover, chemical resistance, heat resistance and light resistance.
Although there are obvious differences between dyes and pigments, it is not possible to give them a precise definition, the classification of pigments in plastic toners is not always completely clear, a small number of organic pigments can be dissolved in certain polymers, insoluble in most polymers; Pigments, and can provide bright red, however in polycarbonate when the temperature is above 330 degrees C (626 degrees F) it dissolves and provides fluorescent yellow, in polycarbonate pigment red 254 behaves like a dye. Pigments and dyes are different, but they can be used in certain situations. For example, some tantalum reduction dyes, they are insoluble dyes, but after pigmentation can also be used as pigments. Such as reducing blue 4 pigmentization is pigment blue 60.
dyes are structurally organic, but pigments can be organic or inorganic. The performance of these two types of pigments is very different from each other, inorganic pigments are metal oxides and metal salts, the same type of inorganic pigments have a lot in common. Inorganic pigments are insoluble in ordinary solvents and are better heat resistant than organic pigments. Organic pigments, on the other hand, generally have a higher coloring power than inorganic pigments.
, all kinds of colorant properties applied to plastics areApplied to plastic organic pigments bright colors, such as organic pigments benzene yellow G, Yonggu yellow 2GS, Yonggu yellow HR, pigment red 254, Yonggu orange G and so on, for plastic products, has a bright color, good migration resistance, product stability, easy dispersion, low filtration value characteristics, there are other pigments can not be replaced by superiority, non-machine pigment color spectrum is not wide, color resistance is low. Solvent dyes affected by migration cannot be used on polyolefin plastics, but only in amorphoine polymers (e.g. PS, ABS and other engineering plastics).
, the use of plastic environment is different, so we should fully consider the colorant chemical resistanceDue to the different environment in which plastics are used, full consideration should be given to the chemical resistance of colorants, such as PVC and other chlorine-containing polymerization easily decomposed to produce hydrogen chloride, the coloring effect of colorants and color-resistant fastness may have a greater impact, so PVC and other chlorine-containing polymer products must use acid-resistant colorants; Plastics such as PVC and polyethylene are widely used as insulation or sheaths for wire and cable, and these applications require colorants to have good electrical insulation properties, some of which, when added, can lead to a decrease in electrical insulation.
Generally caused by the reduction of electrical insulation performance is mainly due to the residual electrolyte of the pigment surface, but not the pigment itself, so some pigments containing soluble salts are not suitable for the coloration of plastic products such as wire and cable, usually carbon black, titanium white powder, chromium yellow, indistinct blue and other pigments have better electrical performance. Eco-friendly performance. With the increasingly strict environmental regulations at home and abroad, many products on the toxicity of plastic colorants put forward strict requirements, colorant toxicity has attracted more and more attention. Now the United States, the European Union and other countries have clearly restricted the use of heavy metals, including cadmium, lead, selenium colorants, Germany and other countries have also introduced regulations to limit the use of some aromatic amine dyes and organic pigments. At present, china still has a large number of toxic colorants in the production and use, to completely replace still face technical and cost challenges.