Bio-Based Propylene Glycol: An Organic Compound with Multiple Uses

Propylene glycol is used as a humectant in food additives, as well as pharmaceutical and industrial products. Expansion of the aftermarket and growing consumer awareness about the use of propylene glycol as a food additive are set to drive the market growth.

Propylene glycol is a synthetic liquid substance that absorbs water. It is a type of synthetic organic compound with the chemical formula C₃H₈O₂ and can be used to make polyester compounds, and as a base for de-icing solutions. 

Propylene glycol is a syrupy liquid at room temperature and is clear and colorless. It exists in air in the form of vapor, although it must be heated or briskly shaken to produce vapor. Propylene glycol is practically odorless and tasteless. Propylene Glycol is obtained by refining oil and natural gas processing. It is also found naturally as a byproduct of fermentation.

Propylene glycol is hygroscopic in nature. This makes it miscible in water, chloroform, and acetone. It is also used to reduce the freezing point of chemicals. Propylene glycol can be segmented into bio-based propylene glycol and petroleum-based propylene glycol. The production of petrochemical-based products releases toxic pollutants. As people become more aware of the harmful effects of petroleum to the environment, the demand for bio-based propylene glycol will grow exponentially. 

Several industries use propylene glycol in the form of monopropylene glycol and dipropylene glycol. Monopropylene glycol is colorless, viscous, and odorless liquid. It has high capability of attracting water, esters, ketones, and amines. The most important application of this substance is that it is used in the production of unsaturated polyester resin. Dipropylene glycol is same as monopropylene glycol. The only difference is, it can be used in various other applications such as unsaturated polyester resins, plasticizers, alkyd resins, cosmetics and urethane polyols.

Propylene glycol is used as a solvent in the pharmaceutical industry. In cosmetics, it helps stabilize products, protecting them from freezing at lower temperatures and melting at higher temperatures. In food, it helps to preserve moisture and dissolve flavors and colors. As shown in the above graph, propylene glycol is majorly used in seasonings and flavorings of food. Some of the foods that contain propylene glycol but are generally not listed on the ingredient labels include soft drinks, frozen meals, artificial sweeteners, foods with natural flavorings, spices, marinades and dressings, cake mixes, frosting, food colorings, and baked goods.

Unsaturated polyester resins are made by condensation of unsaturated acids and diols with/without diacids. These resins form extremely durable structures and coatings when cross-linked with a vinyl reactive monomer.

Unsaturated polyesters resins are used commercially in vast quantities. They were initially used as the coating in wire insulation and later followed by the rapid development of glass reinforced resins, using a matched metal die molding, and hand layup technique. 

According to the graph above, unsaturated polyester resin is likely to grow in the upcoming years due to many new applications. According to IndustryArc Expert Insights, propylene glycol market revenue with respect to unsaturated polyester resin was $1,227.88 million in 2017 and is expected to reach $1,514.39 million by 2023. For instance, the construction market and wind energy sector have displayed high growth in the previous years, which is expected to continue in the next few years, thus offering revenue generation opportunities for unsaturated polyester resins manufacturers.

The economic outlook for the Asia-Pacific region is favorable, owing to the major economic development in China and other developing countries. All the major players of the propylene glycol market have established their operations in this region. China and India hold the maximum share of the propylene glycol market in the APAC region. The factors that led to the growth in this region are rapid industrialization and a humungous amount of construction. Economic development, followed by significant investments in transportation and construction is responsible for the growth of the propylene glycol production in the region.  According to the International Monetary Fund, the economic growth in the APAC region is estimated to be around 5.5%-6% during the period 2017–2020. 

There has been controversy regarding propylene glycol as some researchers believe that propylene glycol can be harmful to the human body and others say that it is harmless. There are several health concerns associated with propylene glycol, it can retain the growth in infants and affect pregnant women, cause liver and kidney failure, allergies, cardiovascular, and neurological symptoms. These issues can be addressed with bio-based propylene glycol in the near future. Governments along with various organizations has developed regulations and guidelines for the usage propylene glycol. These regulations are designed to protect the public from potential adverse health and effects. The Food and Drug Administration has classified propylene glycol as safe, which means it can be used in flavoring drugs, in cosmetics, and as a direct food additive. According to the Department of Health and Human Services, propylene glycol breaks down at the same rate as ethylene glycol, although it does not form harmful crystals during the process. The market is growing and the glycol suppliers are evolving, to meet the challenges of regulations, rising consumer demands, and increased emphasis on sustainable products, globalization, cost pressures, and more.