Colors family – Inks, Dyes and Pigments

Introduction

Color provides a significant glimpse to our world. Every day materials we tend to use different kinds of materials like — textiles, paints, plastics, paper, and foodstuffs. Colors make them most appealing. In summer there is a wild burst of colorful flowers and new leaves of various shades of green on trees.

However, in contrast autumn makes the beautiful impression with green leaves turn to brilliant shades of yellow, orange, and red. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors.

Dye is nothing but colored substance that has an affinity to the substrate to which it is being applied. The dye is applied in an aqueous solution, and needs a mordant to boost the fastness of the dye on the textile fiber.

Pigment may be a material that modifies the color of mirrored or transmitted light as the result of wavelength-selective absorption. Pigments are used for coloring paint, ink, plastic, fabric, cosmetics, food and other materials.

Both dyes and pigments appear to be colored as a result of absorption of some wavelengths of light more than others.

Ink may be a liquid or paste form contains pigments or dyes. Inks are used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, or quill.

Dyes

A dye is a colored substance that has an affinity to the substrate to which it is being applied. It is an ionizing and aromatic organic compound, with Chromophores as a major component. Their structures have Aryl rings that have delocalized electron systems. These structures are said to be responsible for the absorption of electromagnetic radiation that has varying wavelengths, based upon the energy of the electron clouds.

History of Dyes

Dyes usage was started in 2600 BC in china and followed by

  • 715 BC Wool dyeing established as craft in Rome
  • 55 BC Romans found painted people “picti”
  • 2ND and 3RD Centuries AD Roman graves found with madder and indigo dyed textiles
  • 1200's Rucellia, of Florence, rediscovered the ancient art of making purple dye from lichens
  • 1321 Brazilwood was first mentioned as a dye
  • 1507 France, Holland and Germany begin the cultivation of dye plants as an industry
  • 1630 Drebbel produced a new brilliant red dye from sources like cochineal and tin
  • 1774 Scheele discovered chlorine destroyed vegetable colors
  • 1774 Prussian Blue and Sulfuric acid are started available in commercial market
  • 1775 Bancroft introduced the use of quercitron bark as a natural dye
  • 1834 Runge, a German chemist developed aniline dyes
  • 1856 William Henry Perkin discovered the first synthetic dye “Mauve”
  • 1858–59 Verguin discovered Magenta (fuchsin) dye
  • 1861 Lauth discovered basic dye called Methyl violet
  • 1862 Martius and Lightfoot developed Bismarck Brown
  • 1863 Lightfoot developed Aniline Black
  • 1868 Graebe and Liebermann produced alizarin dye
  • 1872 Lauth and Baubigny developed Methyl Green
  • 1873 Groissant and Bretonniere produced Cachou de Laval sulphur dye
  • 1876 Methyl Blue discovered by Caro
  • 1877 Dobner & Fisher discovered Malachite Green discovered
  • 1878 Biebrich Scarlet invented red acid dye
  • 1878 von Baeyer synthesized synthetic indigo
  • 1880 Thomas and Holliday synthesized azo dye
  • 1884 Bottiger discovered Congo Red [cotton dye]
  • 1885 Duisberg produced Benzopurpurine direct dye
  • 1885 von Gallois and Ullrich discovered Para Red dye
  • 1901 Rene Bohn invented and patented Indanthrene Blue RS
  • 1901 Bohn Flanthrene vat dye
  • 1905 Freidlander discovered Thio-indigo Red
  • 1908 Cassella developed Hydron Blue
  • 1921 Bader developed soluble vat colors
  • 1924 Baeyer and Sunder companies produced Indigosol 0
  • 1951 Geigy introduced Irgalan dyes
  • 1956 Eastman Kodak introduced Verel
  • 1957 CIBA introduces Cibacrons reactive dyes

Dyeing process

Dyeing is the method of adding color to textile products like fibers, yarns, fabrics, leather, plastics, paint, printing and many others. Dyeing is normally done in a special solution containing dyes and particular chemical material.

Dyeing process of textiles

In textile dyeing process widely used chemicals like

Classification of dyes

Dyes are classified based on following factors

  • Chemical composition
  • Nature of nuclear structure
  • Various industrial uses
  • Sources of origin
  • Miscellaneous factors

Dyes which are classified based on chemical composition are

  • Acridine dyes
  • Anthraquinone dyes
  • Arylmethane dyes
  • Azo dyes
  • Cyanine dyes
  • Diazonium dyes
  • Nitro dyes
  • Nitroso dyes
  • Phthalocyanine dyes
  • Azin dyes
  • Eurhodin dyes
  • Safranin dyes
  • Xanthene dyes
  • Indophenol dyes
  • Oxazin dyes
  • Oxazone dyes
  • Thiazin dyes
  • Thiazole dyes
  • Fluorene dyes
  • Rhodamine dyes
  • Pyronin dyes

Dyes which are classified based on industrial uses are

Acid dyes — water-soluble anionic dyes applied from acidic dye baths to nylon, silk, wool, modified acrylics

Azoic dyes – contains azo group

Basic dyes – water-soluble cationic dyes

Direct dyes — water-soluble anionic dyes applied to dyeing of cotton, regenerated cellulose, paper and leather

Disperse dyes — water-insoluble nonionic dyes

Reactive dyes – used in materials like cotton, rayon, nylons

Solvent dyes – water-insoluble, soluble in alcohols, chlorinated hydrocarbons, or liquid ammonia

Sulfur dyes — water-insoluble, low cost, good fastness dyes

Vat dyes — insoluble complex polycyclic molecules

Mordant dyes – used to improve the fastness of the dye against water

Dyes which are classified based on Sources of origin are

Dyes which are classified based on miscellaneous factors

  • Fluorescent Dyes
  • Oxidation Dyes
  • Fuel Dyes
  • Leather Dyes
  • Optical Brighteners
  • Leuco Dyes
  • Sublimation Dyes
  • Smoke Dyes
  • Inkjet Dyes
  • Solvent Dyes

Pigments

Pigments appear the colors they are because they selectively reflect and absorb certain wavelengths of visible light. The appearance of pigments is intimately connected to the color of the source light. Pigments are water-and oil-insoluble natural and synthetic products that impart color to materials.

History of Pigments

Pigments and paint grinding equipment believed to be between 350,000 and 400,000 years.

  • In 1200 BCE Phonecians produced Tyrian Purple
  • In 1453 CE Greeks and Romans also used pigments
  • In 1453 CE Greeks and Romans also used pigments
  • In 16the centaury Spain people used pigments
  • In 17th centaury Dutch master Johannes Vermeer used pigments for paintings
  • In 18th century Chrome Yellow, Cobalt Blue were came to usage
  • In 19th centaury Cadmium Red came into existence
  • In 20th centaury Hoechst company introduced the Hansa yellow pigment

Classification of Pigments

Biological pigments – used in biological process like Camouflage, Mimicry, Aposematism and Sexual selection.

Examples: chlorophyll; canthaxanthin; anthocyanin; rhodopsin; myoglobin

Organic pigments – Pigment Red 170; Indian Yellow; indigo; Alizarin; Alizarin Crimson

Inorganic pigments — carbon black; Cadmium Yellow; Cadmium Orange; Cadmium Red; Prussian Blue; Venetian red; Chrome Yellow; Naples Yellow; titanium white

Inks

Ink can be a complex medium, composed of solvents, pigments, dyes, resins, lubricants, solubilizers, surfactants, particulate matter, fluorescers, and other materials. Solvents or carriers enable inks to be applied in the liquid state.

History of inks

The history of Chinese inks can be traced back to the 23rd century BC

The India ink used in ancient India since at least the 4th century BC

1,600 years ago, a popular ink recipe was created

In the 15th century, a new type of ink had to be developed in Europe

Types of Printing inks

Pad printing inks

Screen printing inks

Pad printing inks have formulations comparable to screen printing inks. Pad printing inks are formulated for rapid solvent evaporation.

Screen printing inks are designed to resist rapid evaporation so that they don’t dry in the screen.

Inks can be distinguished according to the way curing takes place

  • Air-curing inks
  • Heat-curing inks
  • Two-component inks
  • UV-curing inks
  • Oxygen-curing inks
  • Sublimation inks

Air-curing inks — is designed not to be heat set and cure at normal air temperature after printing.

Heat-curing inks require elevated temperatures for curing. The use of these ink systems is limited by the high curing temperature that the plastic must be able to withstand.

Two-component inks have the big advantage that no volatile components evaporate during curing. Pot-life after mixing is however limited.

UV-curing inks are widely used for screen-printing. The curing process is fast and environmental problems are smaller than for solvent-based systems. Small changes in ambient conditions have little influence, which makes the printing process very stable.

UV-curing inks are widely used for screen-printing. The curing process is fast and environmental problems are smaller than for solvent-based systems. Small changes in ambient conditions have little influence, which makes the printing process very stable.

Sublimation inks are heated to a temperature of about 200ºC (392ºF) during the application process, so that dyes in the ink sublime and are absorbed by the polymer surface while they are in the gas state. Sublimation inks are in the solid state at ambient temperature, like a wax, and become fluid when raised to 80ºC (176ºF) in the ink reservoir

To contact the author mail: articles@worldofchemicals.com

© WOC Article

Originally published at www.worldofchemicals.com.

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