Most synthetic esters are produced by combining carboxylic acids and alcohols, and perfectly combine biodegradability, performance and superior lubricating properties. 

Esters can be used both as a base stock and an additive in lubricants and boast characteristics suited to even the most demanding environments. Their versatility makes them ideal for varied industrial applications, thanks to characteristics including good lubricity, oxidation stability, low volatility, high temperature resistance, and reduced flammability. 

Given their superior functionality, these API Group V base oils are often used in greases, hydraulic fluids, compressor oils and gear and chain lubricants in aviation, refrigeration, metalworking and the automotive sector. 

The esters market is forecast to grow by a compound annual rate of 5.5% through to 2035, according to a report published by research firm Future Market Insights Inc. The recent study noted that high-performance esters are seeing a “tremendous rise in the aerospace, automotive and heavy machinery industries, especially for high-temperature lubricants, fire-resistant fluids and advanced plasticizers.”

Matthias Hof, global business manager of biolube esters at Emery Oleochemicals, noted that esters remain a relatively niche market but said it is packed with potential. 

Despite gaining traction in recent years, esters have struggled to capture significant market share from the more established and more affordable petrochemical oils and components. Current demand for esters is best described as steady and stable with a growth rate slightly higher than the lubricant market, he said. 

“The original thinking of using more renewable and environmentally benign esters is still there, but not to the extent that their volumes in the lubricant space have experienced the big boost in demand that had been expected,” said Hof.

“You also have to factor in that the current economic climate is not positive for higher priced technologies such as esters,” he added. “Key drivers such as sustainability are not necessarily as dominant either.”

“Right now, companies are thinking more about cost optimization; they’re trying to consolidate their supply chain and that, of course, is putting pressure on the industry,” continued Hof. “The versatility of esters is still there, the advantages of ester technology are still there, but the consciousness about the costs has not changed.”

This slower than anticipated growth for esters can also be attributed to improvements in lubricant formulation technology and the development of higher quality, better performing products, according to consultancy Kline & Co. in its four quarter 2023 report, “Industrial Esters: Market Analysis and Opportunities.”

Kline’s report highlighted that acrylic esters, carboxylic acid esters, fatty acid esters and carbonic acid esters currently represent around 90 percent of global esters demand. 

There are noticeable regional differences for ester uptake, it added. The Indian and Southeast Asian markets are seeing strong growth, and China continues to dominate. However, the more mature U.S. and European markets are expected to see markedly slower growth in the coming years.

The study pointed to numerous factors affecting esters demand: environmental regulation, inflation, the weakening construction sector in China, increasing volumes of lithium-ion batteries for electric vehicles and the ongoing tensions in Ukraine and the Middle East. As a result of these prevailing issues and trends, Kline has forecast a 3% CAGR by 2027 for the esters market.

According to Hof, innovation is being somewhat stymied due to reliance on “known technologies.” The development of new, more customized products has been relatively slow, he said, partially due to the associated costs and the many and numerous hurdles posed by regulation.

“The introduction of new chemistries will, in my opinion, only be best triggered by new applications coming to the market and changing demands coming from areas such as electromobility,” he added.

“A lot of ester companies are investing their resources into this area to see how their technology can be implemented in this changing landscape. They’re looking at what the benefits are compared to more established technologies and whether those needs can be met with existing assets or if new products are needed.

“But the move towards electromobility is still not really progressing as quickly as everybody had thought. Changes in the hardware technology in thermal management, for example, and the switch from indirect to direct and immersion cooling is not happening as fast as anticipated, which means the adoption of esters is slower too.” Hof noted that the customization of componentry for end users has proved challenging due to the listing and regulation requirements. 

“The performance benefits are still there, but esters’ growth has not been realized to the extent it has been projected,” he continued. “In the end, it’s cost performance that will be decisive; you have to show how the higher price for these esters is justified.” 

Esters clearly have innumerable attributes and vast potential. For now, however, their widespread adoption is still somewhat limited. Moving forward, a lot will depend on the availability of raw materials, environmental policy, regional demand – and importantly, affordability. But with a growing appetite for high-performance formulations and more sustainable options, esters will likely have an increasingly important role to play in the years ahead.

In this issue’s Spotlight, LANXESS looks at the many benefits and advantages of ester base stocks.  

Lubricant Ester Base Stocks Offer a Sustainable Solution

As industries increasingly prioritize sustainability and performance, synthetic esters derived from polyols and oleic acid have gained significant attention as advanced lubricant base stocks. These esters offer a compelling combination of high thermal stability, excellent lubricity, and environmental compatibility, making them suitable for a wide range of industrial
applications.

Polyol esters are synthetic compounds formed through the esterification of polyhydric alcohols (polyols) with fatty acids. Common polyols include pentaerythritol, trimethylolpropane (TMP), and neopentyl glycol, each contributing to the molecular structure and performance characteristics of the final ester. When these polyols are reacted with oleic acid, a monounsaturated fatty acid typically sourced from vegetable oils, the result is a lubricant base stock with a unique balance of properties.

The molecular structure of polyol esters allows for multiple ester linkages, which enhances oxidative stability and thermal resistance. Oleic acid, with its long hydrocarbon chain and single double bond, contributes to excellent lubricity and biodegradability. This combination makes polyol oleate esters particularly attractive for applications where both performance and environmental safety are critical.

Esters are ideal for an ever-growing range of demanding applications thanks to their many key advantages:

• High thermal stability. By being able to withstand elevated temperatures without significant degradation, esters are ideal for high-load, high-speed machinery, and systems operating under continuous stress.

• Excellent lubricity. The inherent polarity of ester molecules allows them to form strong, stable films on metal surfaces, reducing friction and wear. This leads to improved energy efficiency and extended equipment life.

• Biodegradability. Polyol esters made from oleic acid are readily biodegradable and non-toxic, making them suitable for use in environmentally sensitive areas. They meet or exceed OECD biodegradability standards.

• Low volatility. Esters’ high molecular weight and strong intermolecular forces result in low evaporation rates, which helps maintain lubricant volume and performance over time, especially in high-temperature environments.

• High fire and flash points. Compared to mineral oils, polyol esters exhibit significantly higher fire and flash points. This makes them safer for use in applications where fire hazards are a concern, such as metalworking, foundries, and industrial processing.

• Additive compatibility. Esters blend well with a wide range of performance additives, allowing formulators to tailor lubricants for specific needs, including anti-wear, corrosion inhibition, and extreme pressure resistance. 

Polyol oleate esters are suited to a diverse array of lubricant formulations across multiple sectors. In biodegradable hydraulic fluids, they are perfect for use across forestry, agriculture, and marine operations – particularly in hydraulic systems where fluid leakage could pose an environmental risk. Their biodegradability and low ecotoxicity make them compliant with environmental regulations.

Another key outlet is metalworking fluids, where their lubricity and high flash points make them suitable for cutting, grinding, and forming operations. They help to reduce tool wear and improve surface finish quality.

As either a primary base stock or an additive, LANXESS’ Hatcol^® synthetic ester base stocks are relied upon for automotive, industrial, and food-grade applications thanks to their excellent levels of performance and versatility. 

The use of oleic acid from renewable plant sources supports the development of bio-based lubricants, reducing reliance on petroleum-derived products. This contributes to a lower carbon footprint and supports circular economy principles.

Moreover, many of these esters are eligible for inclusion in the European Ecolabel Lubricant Substance Classification (LuSC) list. This list identifies substances that meet the stringent environmental and technical criteria required for lubricants to carry the EU Ecolabel. Inclusion in the LuSC list confirms that these esters are readily biodegradable, non-toxic to aquatic life, derived from renewable raw materials, and compliant with strict oxidative and thermal stability standards.

This certification enables lubricant manufacturers to develop Environmentally Acceptable Lubricants (EALs) for use in sensitive ecosystems, helping industries meet regulatory requirements while advancing sustainability goals.

To find out more about LANXESS and how our range of Hatcol^® synthetic ester base stocks can meet the needs of your application, visit the website at https://lanxess.com/en/products-and-brands/brands/hatcol