Propylene glycol

Propylene glycol is used as antifreeze in breweries and diaries, in the manufacture of resins, as a solvent, and as an emulsifier in food. It was present as an occupational sensitizer in the color-film developer Flexicolor.

Propylene glycol has a slight, characteristic taste. It is practically odorless. It absorbs moisture when exposed to moist air.

Propylene glycol is a colorless, odorless, syrupy liquid.

An alcohol in which the hydroxyl groups are attached to a carbon atom of a branched or straight-chain aliphatic hydrocarbon.

Thick odorless colorless liquid. Mixes with water.

Propylene glycol is used for similar applications as other glycols.Propylene glycol is an important raw material for unsaturated polyester, epoxy resin, and polyurethane resin. The use amount in this area accounts for about 45% of the total consumption of propylene glycol. Such unsaturated polyester is used extensively for reinforced plastics and surface coatings. Propylene glycol is excellent in viscosity and hygroscopicity and is non-toxic, and thus is widely used as hygroscopic agent, antifreeze, lubricants and solvents in the food, pharmaceutical and cosmetic industry. In the food industry, propylene glycol reacts with fatty acid to give propylene ester of fatty acids, and is mainly used as food emulsifier; Propylene glycol is a good solvent for flavorings and pigments. Propylene glycol is commonly used as solvents, softeners and excipients, etc. in the pharmaceutical industry for the manufacture of various types of ointments and salves. Propylene glycol is also used as a solvent and a softener for cosmetic since it has good mutual solubility with various spices. Propylene glycol is also used as tobacco moisturizing agents, antifungal agents, food processing equipment lubricants and solvents for food marking ink. Aqueous solution of propylene glycol is an effective anti-freeze agent.

Propylene Glycol is a humectant and flavor solvent that is a polyhy- dric alcohol (polyol). it is a clear, viscous liquid with complete solu- bility in water at 20°c and good oil solvency. it functions as a humectant, as do glycerol and sorbitol, in maintaining the desired moisture content and texture in foods such as shredded coconut and icings. it functions as a solvent for flavors and colors that are insoluble in water. it is also used in beverages and candy.

Used as a solvent.

Next to water, propylene glycol is the most common moisturecarrying vehicle used in cosmetic formulations. It has better skin permeation than glycerin, and it also gives a pleasant feel with less greasiness than glycerin. Propylene glycol is used as a humectant because it absorbs water from the air. It also serves as a solvent for anti-oxidants and preservatives. In addition, it has preservative properties against bacteria and fungi when used in concentrations of 16 percent or higher. There is a concern that propylene glycol is an irritant at high concentrations, though it appears to be quite safe at usage levels under 5 percent.

Propylene glycol generally is synthesized commercially by starting with propylene, converting to the chlorohydrin, and hydrolyzing to propylene oxide, which is then hydrolyzed to propylene glycol. It can also be prepared by other methods.