A solvent dye is a type of color dye that dissolves in organic solvents, creating a solution. The ability to mix with solvents is due to the non-polar nature of the dye chemicals. This class of colorings is used in a range of products including ink, plastics, and resins. Within the class of solvent dyes, there are other types of dyes that relate to specific colors, such as red or yellow and green or blue.
Chemicals that can easily dissolve in other chemicals and form a solution are called solvents. They cannot, however, be dissolved in water. These dyes are completely soluble in organic solvents, which means they will not form a separate layer or residue. The ability of the dye to completely dissolve is important to achieve a consistent color.
Unlike other colorings, solvent dyes do not easily ionize. Ionization refers to a compound's ability to change polarity by gaining or losing an electron from another compound. This function is why solvent dyes do not dissolve in water, a highly polar substance. This dye class tends to be made of aromatic, colored compounds that easily dissolve. The naming system for these dyes use a color index, following a classification system: solvent + color + number; solvent blue 35. This system is based strictly on color, and not the chemicals used in each of the different dyes.
The chemical activity of these colorings are important as they can dissolve in non-polar chemicals. Common non-polar compounds are oils, fats and fuels. Solvent dyes are used extensively to color plastics. Other uses include coloring resins, wood stains and waxes. The color in pen inks, candles and printing ink are made of these colored dyes.
There are scientific uses for these dyes, as they are used in solutions that stain the different structures found in cells. These stains are used in research as well as medical diagnostics. Dyes can even be customized for specific processes.
Yellow and red colored solvent dyes are also known as azo dyes. These are synthetic and contain a nitrogen double bonded to another nitrogen. This is known as an azo group. As many as 70 percent of all textile and food dyes are azo colors.
Green and blue solvent dyes are commonly known as anthraquinone dyes. Anthraquinones are chemicals that have the molecular structure containing 14 carbons, eight hydrogens and two oxygens. By adding an amino group of hydroxyl group to the basic structure, a range of colors is created.