Innovations in Polyalkylene Glycol-Based Lubricants

So long as there is friction, there will be lubricants – this is a statement that could be the cornerstone of the lubricant industry. Emerging technologies in engine and powertrain technologies usually coincide with breakthroughs in lubricant technology, and consequently, advancements in lubricant technology represent an area of continuous improvement. Over the course of half a century, the world has seen automotive companies gradually switching from mineral oil-based lubricants to synthetic lubricants and that has also accelerated industry growth. By 2019, the global lubricants industry is expected to be a worth over USD162 billion, with Asia and the Middle East being the key drivers of industry growth.

The shift from mineral oil-based lubricants to synthetic lubricants is a strategic one and represents the industry’s focus on improved performance and environmentally responsible industry practices. As engines increase in complexity, synthetic lubricant chemistries have evolved from the use of simple diesters and neopentyl poly esters to silicone-based lubricants for brake fluids, poly-α-olefin as high-performance compressor and automotive lubricants, and fire-resistant phosphate esters for use in aircraft and ultra-high-performance engines.

Polyalkylene Glycol (PAG)-based lubricants have been in use for over fifty years, with fire-retardant properties and one of the wider temperature ranges among synthetic or oil-based lubricants. Their versatility has been a factor that has led to their use in food processing and in the automotive industry. PAG lubricants possess excellent solubility, viscosity, low volatility and do not produce significant residues or deposits on moving parts. Today, PAGs are the lubricants of choice in the automotive industry through several critical innovations that greatly improve the performance of lubricants.

Oil Solubility: Unlocking New Frontiers

A lubricant that offers good residue control, has a low volatility, sufficient viscosity, is further enhanced by being water-soluble. The water-solubility of PAGs ensures their easy cleanup and makes them the lubricant of choice for automotive air conditioning compressors, brake fluids and other key compressor-based applications. However, newer PAGs exhibit oil tolerance and oil solubility, two properties that expand the applications of these lubricants.

Researchers and industry experts claim that these new PAGs are a once-in-a-generation evolutionary leap in that their oil solubility means that they are miscible with mineral oils or some synthetic oils to act as cleaning agents without compromising the volatility, viscosity, and consequently, the performance of the lubricant or the moving parts. This also unlocks a plethora of possibilities in using new blends of oil and PAGs to reduce overall cost and improve performance.

Yet a third advantage of PAGs is their low chance of polymerization, in part, due to their relatively good pour point—the point at which a lubricant loses the property of flowing—and high viscosity index—a measure of how rapidly viscosity changes with the increase in temperature. The use of PAGs also results in a lower probability of varnishing, a phenomenon where lubricant degradation or polymerization cause deposits to form on the surface of moving parts. When the lubricating mix is composed purely of mineral oils with or without additives, over time, the breakdown of these oils leaves behind a highly viscous deposit that attracts dirt and other deposits that have a sandpaper-like effect, accelerating the wear of mechanical parts. Newer PAG chemistries help to prevent this phenomenon, greatly extending longevity and performance.

It is important to note that PAG formulations have some drawbacks. They are non-renewable lubricants and consequently, need safe disposal. Despite this property, PAGs are popular in an automotive application for their relatively low cost and better biodegradability when compared with mineral or poly-α-olefin lubricants. New PAG lubricants also offer better rust prevention, soot control, and sludge prevention than older formulations, making them ideal for a wide range of automotive applications. When combined with biosynthetic lubricants, these innovative lubricants are ideal for use in diesel engines, mobile hydraulic devices, marine engines and hydraulics, and heavy-duty industrial gear oils.