Boasting both flexibility and high levels of performance, synthetic esters have seen intensified interest in recent years. Now, with environmental pressures growing and applications getting even more demanding, their popularity is increasing and use is widespread.
While esters still represent only a comparatively small proportion of the overall base oil market, their relevance and importance continues to grow.
Esters are a diverse product group offering differing levels of performance depending on the technology and raw materials that are used. They are polar molecules, derived either from crude oil products or from biobased sources. Synthetic esters are produced by combining carboxylic acids and alcohols, allowing for almost countless combinations and permutations-and can therefore be tailored to meet specific requirements.
An alternative to mineral oils, these API Group V base oils are hugely versatile and are recognized for their high levels of performance. They are particularly suited to severe operating conditions and sensitive environmental conditions where attributes such as hydrolytic stability, low toxicity, high temperature resistance, reduced flammability and good lubricity are needed. In fact, some of these attributes helped esters first gain prevalence during the development of jet fighter aircraft decades ago.
Compared with mineral oils, the use of esters is sometimes seen as cost prohibitive for some applications as they are often several times more expensive. However, their longevity and unique properties can help to offset this. Esters are also commonly used as a co-base fluid or additive in many formulations to bring performance benefits at a lower cost than a fully ester based product.
There are many types of esters that cater to different needs, thanks to their varied properties and characteristics. Each have their benefits and limitations. Fatty acid esters, for example, are made from animal or vegetable fats and oils and offer good oxidative stability. Diesters, meanwhile, (produced by reacting dibasic acid and alcohol) and polyol esters (based on monobasic acid and polyhydric alcohol) are suited for use at high temperatures but some suffer from poor hydrolytic stability. Phosphate esters (made from phosphoric acid and alcohol) are fire resistant and hard-wearing, but are not miscible with mineral oils. Complex polyol esters are a combination of diacids and polyol esters, which provide both thermal stability and good viscosity.
Esters are commonly used in myriad applications ranging from industrial lubricants, hydraulics, marine and automotive, to refrigeration, metalworking and wind turbines.
The global ester base stock market has enjoyed healthy levels of growth over the past few years and demand continues to climb. According to research from Global Market Insights (http://bit.ly/2ChRqXq), the synthetic lubricants marketis expected to achieve growth in excess of 4 percent from 2016 to 2023 and total over $5 billion in sales by 2023. Esters represent a fairly significant share of the market, the firm says, and will reach over $1.7 billion by the end of this period, stimulated by demand for reciprocating compressor oils.
Constantly Evolving
Regulations requiring lubricants to be environmentally acceptable, biodegradable and non-toxic have always affected the ester base stock market and will continue to be one of the major growth drivers moving forward, noted BASF.
With environmental pressures mounting and increasing awareness of these issues, end consumers and business-to-business customers are factoring sustainability criteria into their product selection, added the German chemicals producer. As a result, esters have become the most widely used lubricant category for environmentally sensitive applications because of their biodegradability, low toxicity, resource efficiency and renewable attributes.
Further, advancing technology requires higher levels of performance that cannot always be achieved with conventional products, said esters producer Lanxess.
Esters are viewed as a potential base stock for next-generation, ultra-low-viscosity engine oils, which BASF said can be efficiently and reliably supplied using widely available petrochemical raw materials at an attractive cost-performance ratio. Changing performance requirements and sustainability trends such as e-mobility and demand for better fuel economy may also affect their selection.
Lanxess pointed out that these ever-advancing performance requirements are indeed driving demand for synthetic lubricants in the automotive world. Its brand of polyol esters, for example, have been designed for use where extreme temperatures and severe conditions generate heavy stresses. They provide easier starts, longer drain intervals, reduced wear and better fuel economy, the company said. For industrial applications, these esters can increase up-time, reduce maintenance costs and extend thermal stability.
Past Performance, Future Potential
Emery Oleochemicals believes these are exciting times for the burgeoning esters market, particularly given that it expects to see steady demand growth in the coming years thanks to toughening industry requirements and the need for higher performing lubes.
Car manufacturers, for example, are pushing for greater efficiencies and higher gas mileage, while more demanding standards, such as the ILSAC GF-6 passenger car engine oil specification, will require higher performance additives. This will increase the uptake of esters moving forward, Emery predicted.
Biobased esters green credentials, versatility and high levels of performance have contributed to the perception that they are an expensive alternative to other base stocks. Emery noted that it is working hard to inform, evangelize and educate the market that natural-based esters, when compared to synthetic esters, are effective, environmentally friendly and cost competitive.
Italmatch Chemicals suggested there are no real limitations or downsides to esters and that there is plenty of scope for new applications in the future.
The market for esters is dynamic and, from our perspective, they are a great solution when it comes to performance, viability and longevity of your fluids, said David Millin, global vice president of sales and marketing for lubricant performance additives. Were seeing a global trend for higher performing, longer lasting and more environmentally friendly fluids.
Over the years there has been steady growth in the use of esters in lubrication, and we have continued to invest in manufacturing capacity to make these high-performance solutions, he said.
There seems to be significant potential for esters and considerable scope for new applications, particularly in more severe environments. As demand increases, cost should become less of a factor.
In this Spotlight, Emery Oleochemicals and Lanxess consider both the importance of esters and future opportunities.