What are Glycol ethers?
The glycol ethers family
Glycol ethers form a varied family of more than 30 solvents. All these glycol ethers have different properties – and are therefore fit for different uses. They are an invaluable solution for industries but are also part of everyday life. Uses range from pharmaceuticals and micro-electronics to domestic cleaning, personal care and printing. We demand high standards from products today – from the purity of penicillin to the performance of paint – none of which would be possible without solvents.
Traditionally, a distinction is made between two main groups of glycol ethers: E series and P series, depending on whether they are made from ethylene or propylene. In each group, different derivatives have been developed to provide the properties of solubility, volatility, compatibility and inflammability required for the applications.
Commercial E-series glycol ethers consist mainly of methyl, ethyl and butyl glycol ethers. Depending on the number of ethylene oxide repetitive units there are mono-, di- and triethylene glycol ethers. The ethylene oxide building block provides a high compatibility with water to these compounds. Their use in water-based coatings is an example how this property can be used.
These substances act as solvents and as coalescing aids and coupling solvents in paint formulations. Their coalescing aid property is essential for high quality film formation in water-based paints, while the solvents power of the materials is needed e.g. in cleaning applications.
The higher molecular weight E-series glycol ethers (triethylene glycol ethers or higher homologues) are also used in hydraulic brake fluids.
E-series glycol ethers are also used as intermediates and undergo further chemical reactions e.g. to esters.
Propylene Glycol Ethers are high-performance industrial solvents. P-series glycol ethers are based on reacting propylene oxide with varying chain alcohols.
They are used for paints and coatings, cleaners, inks, and a variety of other applications. In coating applications P-series glycol ethers provide good solvency for a wide variety of resins including acrylic, epoxies, alkyds, polyesters, nitrocellulose and polyurethanes. For cleaners they provide low toxicity, surface tension reduction, and provides good solvency for polar and nonpolar materials. As a chemical intermediate, P-series glycol ethers can be used in combination with other glycol ethers or solvents to custom tailor properties to meet the full requirements of the formulation. In the electronics industry, P-series glycol ethers are also used in conjunction with other solvents in the manufacture of laminates and in semiconductor processes which are used to make circuit boards. Other significant applications are agricultural, cosmetic, ink, textile and adhesives products.