Mono propylene glycol (also known as propylene glycol, PG, propan1, 2diol and MPG) is a clear, colourless, and viscous liquid with a characteristic odour which has the formula C3H8O. It is soluble in water and has hygroscopic properties. MPG is used across a wide range of industries due to its low toxicity coupled with a depressed freezing point upon mixing with water.
Mono propylene glycol is produced mainly from propylene oxide. The most common process is the non-catalytic hydrolysis of propylene oxide in a high-temperature and high-pressure environment. The second method is the catalytic method where it can proceed at 150 °C, in the presence of ion exchange resin, or a small amount of sulfuric acid or alkali. Mono propylene glycol can also be produced from glycerol, a bio-diesel by-product.
Mono propylene glycol is used as a solvent for food colourings and flavourings. It is also classified as a humectant food additive.
In the personal care industry, it is used as moisturizer in make-up, shampoo, bubble bath and baby wipes etc.
Mono propylene glycol is used as a solvent in oral, injectable, and topical formulations.
Air Travel Industry
Mono propylene glycol also has a variety of uses in the air travel industry. The few main applications are antifreeze for aircraft wing and runway de-icer. This is due to the decreased freezing point of MPG upon mixing with water. Mono propylene glycol is also used in heat transfer liquids such as engine coolants.
Mono propylene glycol can be used as a chemical intermediate in the production of high performance unsaturated polyester resins used in paints and varnishes. It is also an excellent solvent that is often used in printing inks as well as manufacturing of non-ionic detergents used in petroleum, sugar-refining, and paper making industries. It can also be used in the cryonics industry and can be used as an additive in pipe tobacco as it prevents dehydration.