Dye
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and may require a mordant to improve the fastness of the dye on the fiber.[2]
The majority of natural dyes are derived from non-animal sources such as roots, berries, bark, leaves, wood, fungi and lichens.[3] However, due to large-scale demand and technological improvements, most dyes used in the modern world are synthetically produced from substances such as petrochemicals.[4] Some are extracted from insects and/or minerals.[5]
Synthetic dyes are produced from various chemicals. The great majority of dyes are obtained in this way because of their superior cost, optical properties (color), and resilience (fastness, mordancy).[2] Both dyes and pigments are colored, because they absorb only some wavelengths of visible light. Dyes are usually soluble in some solvent, whereas pigments are insoluble. Some dyes can be rendered insoluble with the addition of salt to produce a lake pigment.
History
Dyed
Early industrialization was conducted by
The discovery of mauve also led to developments within
Chemistry
The color of a dye is dependent upon the ability of the substance to absorb light within the visible region of the electromagnetic spectrum (380-750 nm). An earlier theory known as Witt theory stated that a colored dye had two components, a
Types
Dyes are classified according to their solubility and chemical properties.[2]
Basic dyes are water-soluble
Direct or
Disperse dyes were originally developed for the dyeing of cellulose acetate, and are water-insoluble. The dyes are finely ground in the presence of a dispersing agent and sold as a paste, or spray-dried and sold as a powder. Their main use is to dye polyester, but they can also be used to dye nylon, cellulose triacetate, and acrylic fibers. In some cases, a dyeing temperature of 130 °C (266 °F) is required, and a pressurized dyebath is used. The very fine particle size gives a large surface area that aids dissolution to allow uptake by the fiber. The dyeing rate can be significantly influenced by the choice of dispersing agent used during the grinding.
Azoic dyeing is a technique in which an insoluble Azo dye is produced directly onto or within the fiber. This is achieved by treating a fiber with both diazoic and coupling components. With suitable adjustment of dyebath conditions the two components react to produce the required insoluble azo dye. This technique of dyeing is unique, in that the final color is controlled by the choice of the diazoic and coupling components. This method of dyeing cotton is declining in importance due to the toxic nature of the chemicals used.
Sulfur dyes are inexpensive dyes used to dye cotton with dark colors. Dyeing is effected by heating the fabric in a solution of an organic compound, typically a nitrophenol derivative, and sulfide or polysulfide. The organic compound reacts with the sulfide source to form dark colors that adhere to the fabric. Sulfur Black 1, the largest selling dye by volume, does not have a well defined chemical structure.
Some dyes commonly used in Staining:
Basic Dyes | Acidic Dyes |
---|---|
Safranin | Eosin |
Basic fuchsin | Acid fuchsin |
Crystal violet | Congo red |
Methylene blue |
Food dyes
One other class that describes the role of dyes, rather than their mode of use, is the food dye. Because food dyes are classed as food additives, they are manufactured to a higher standard than some industrial dyes. Food dyes can be direct, mordant and vat dyes, and their use is strictly controlled by legislation. Many are azo dyes, although anthraquinone and triphenylmethane compounds are used for colors such as green and blue. Some naturally occurring dyes are also used.[20]
Other important dyes
A number of other classes have also been established, including:
- Oxidation bases, for mainly hair and fur
- Laser dyes: rhodamine 6G and coumarin dyes.[21]
- Leather dyes, for leather
- Fluorescent brighteners, for textile fibres and paper
- Solvent dyes, for wood staining and producing colored lacquers, solvent inks, coloring oils, waxes.
- Contrast dyes, injected for magnetic resonance imaging, are essentially the same as clothing dye except they are coupled to an agent that has strong paramagnetic properties.[22]
- Mayhems dye, used in water cooling for looks, often rebranded RIT dye
Chromophoric dyes
By the nature of their chromophore, dyes are divided into:[23]
- Category:Acridine dyes, derivates of acridine
- Category:Anthraquinone dyes, derivates of anthraquinone
- Arylmethane dyes
- Category:Diarylmethane dyes, based on diphenyl methane
- Category:Triarylmethane dyes, derivates of triphenylmethane
- Category:Azo dyes, based on -N=N- azo structure
- Phthalocyanine dyes, derivatives of phthalocyanine
- Quinone-imine dyes, derivatives of quinone
- Category:Azin dyes
- Category:Eurhodin dyes
- Category:Safranih
- dyes, derivates of safranin
- Indamins
- Category:Indophenol dyes, derivates of indophenol
- Category:Oxazin dyes, derivates of oxazin
- Oxazone dyes, derivates of oxazone
- Category:Thiazine dyes
- Category:Azin dyes
- Category:Thiazole dyes
- Category:Safranin dyes
- Xanthene dyes
- Fluorene dyes, derivatives of fluorene
- Pyronin dyes
- Category:Fluorone dyes, based on fluorone
- Category:Rhodamine dyes, derivatives of rhodamine
- Fluorene dyes, derivatives of fluorene
Pollution
Dyes produced by the textile, printing and paper industries are a source of pollution of rivers and waterways.[24] An estimated 700,000 tons of dyestuffs are produced annually (1990 data). The disposal of that material has received much attention, using chemical and biological means.[25]
Vital dyes
A “vital dye” or stain is a dye capable of penetrating living cells or tissues without causing immediate visible degenerative changes.[26] Such dyes are useful in medical and pathological fields in order to selectively color certain structures (such as cells) in order to distinguish them from surrounding tissue and thus make them more visible for study (for instance, under a microscope). As the visibility is meant to allow study of the cells or tissues, it is usually important that the dye not have other effects on the structure or function of the tissue that might impair objective observation.
A distinction is drawn between dyes that are meant to be used on cells that have been removed from the organism prior to study (supravital staining) and dyes that are used within a living body - administered by injection or other means (intravital staining) - as the latter is (for instance) subject to higher safety standards, and must typically be a chemical known to avoid causing adverse effects on any biochemistry (until cleared from the tissue), not just to the tissue being studied, or in the short term.
The term "vital stain" is occasionally used interchangeably with both intravital and supravital stains, the underlying concept in either case being that the cells examined are still alive. In a stricter sense, the term "vital staining" means the polar opposite of "supravital staining." If living cells absorb the stain during supravital staining, they exclude it during "vital staining"; for example, they color negatively while only dead cells color positively, and thus viability can be determined by counting the percentage of total cells that stain negatively. Because the dye determines whether the staining is supravital or intravital, a combination of supravital and vital dyes can be used to more accurately classify cells into various groups (e.g., viable, dead, dying).[27]
See also
- Biological pigment, any colored substance in organisms
- Blue Wool Scale
- Hair coloring
- Industrial dye degradation
- J-aggregate
- Laser dyes
- List of dyes
- Oxidant
- Phototendering
- Stain
- Natural dyes
- Pigments
References
- ISBN 3527306730.
- ^ ISBN 3527306730.
- ISBN 9781579654252. Retrieved 8 November 2017 – via Google Books.
- ^ "dye - Synthetic dyes | Britannica". www.britannica.com. Retrieved 2022-06-20.
- ISBN 978-0-7613-2112-5.
- ISBN 9780203882085. Retrieved 8 November 2017 – via Google Books.
- ISBN 9780486226880. Retrieved 8 November 2017 – via Google Books.
- PMID 19745126.
- ^ John Pullar (1803–1878) - The Courier & Advertiser, 7 June 2016
- .
- S2CID 112031120.
- ^ Eiland, Murray (1999). "Problems Associated with the Dissemination of Synthetic Dyes in the Oriental Carpet Industry". Journal of the International Committee for the History of Technology. 5: 138–59 – via academia.edu.
- ^ Hunger, K., ed. (2003). Industrial Dyes. Chemistry, Properties, Applications. Weinheim: Wiley-VCH.
- ^ Zollinger, H. (2003). Color Chemistry. Synthesis, Properties and Applications of Organic Dyes and Pigments, 3rd ed. Weinheim: Wiley-VCH.
- ISBN 9783906390239.
- ISBN 978-0-19-927789-6. Retrieved February 26, 2021.
- ISSN 1181-8700.
- ISBN 9781139855570. Retrieved 8 November 2017 – via Google Books.
- S2CID 93008250.
- ^ Duarte, F. J.; Hillman, L. W., eds. (1990). Dye Laser Principles. New York.
{{cite book}}
: CS1 maint: location missing publisher (link) - ^ "patentstorm.us". Patentstorm.us. Archived from the original on 12 June 2011. Retrieved 8 November 2017.
- ^ Llewellyn, Bryan D. "Stainsfile - Dye index". Stainsfile.info. Archived from the original on 16 April 2008. Retrieved 8 November 2017.
- ^ Brindley, Lewis (July 2009). "New solution for dye wastewater pollution". Chemistry World. Retrieved 2018-07-08.
- PMID 15488921.
- ^ https://www.merriam-webster.com/medical/vital%20dye
- ^ https://www.intechopen.com/online-first/78967 This article incorporates text available under the CC BY 3.0 license.
Further reading
- Abelshauser, Werner. German History and Global Enterprise: BASF: The History of a Company (2004) covers 1865 to 2000
- Beer, John J. The Emergence of the German Dye Industry (1959)
- Eiland, Murray (1999). "Problems Associated with the Dissemination of Synthetic Dyes in the Oriental Carpet Industry". Journal of the International Committee for the History of Technology. 5: 138–59 – via academia.edu.
- "Synthetic Dye - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-11-18.