Grease is a semi-solid lubricant. It typically comprises soap blended with either mineral or vegetable oil. At times, soft solid or high viscosity liquid materials used as lubricants are described as greases. However, they lack the property of shear-thinning, which is a characteristic of grease. For instance, petroleum jellies (such as Vaseline) are not generally categorized as greases.
Mechanisms in which the lubricating oil remains mobile and which can sustain infrequent lubrications employ greases. Greases can also be used as sealants to avoid contamination with water and incompressible materials. Mechanisms which are lubricated with greases exhibit high frictional characteristics because of their high viscosity.
There are different types of greases which can be classified based on their application requirement and the additives they contain. Grease additives are added to complement the properties of greases according to the requirements of industries, applications, and end-users. For instance, additives used in food applications have been registered with the NSF with an HX-1 approval.
Gear greases comprise rosin oil (containing lime and mineral oil) and water up to some percentage. Greases that can withstand extreme pressure are categorized as EP greases. Normal greases, when put under high pressure or shock loading, can get compressed and can cause physical contact between the greased parts, resulting in friction and wear of the parts. Special-purpose greases contain sorbitan esters and glycerol. They can be used in low temperatures.
Graphite and/or molybdenum disulfide is typically added to solid EP greases for protection under heavy loadings. The metal-to-metal contact and the subsequent friction caused due to thinning of the lubricant film can be avoided when the solid lubricants bond with the metal surface.
Greases with additives such as ceramic powder and copper are employed in high temperature and/or high pressure applications. This helps in preventing corrosion which can create problems during the dis-assembly of the components. These solid additives work as release agents. However, not all types of solid additives can be used in bearings, as they can result in reinforced wear of the bearings.
Oxidation inhibitors offer protection against rust and corrosion, primarily in applications that include water contamination and/or high temperature conditions. Pressure additives offer resistance against extreme heat and pressure. Temperature additives can modify the characteristics of base oil in order to enhance its performance in applications in inconstant temperatures.
Metal wear is reduced by anti-wear agents. It acts by binding itself to the metal surface to form a coating. Metal deactivators protect surfaces from degradation by reducing metal reactivity.
Based on functionality, the grease additives market can be segmented into oxidation inhibitors, pressure additives, temperature additives, anti-wear agents, metal deactivators, and other additives. Based on the type of soap used in grease production (thickeners), the grease additives market can be divided into soap-based (including aluminum soap, calcium soap, lithium soap, sodium soap, and others) and non-soap-based (including polyuria and other complexes). Based on end-user industry, the grease additives market can be classified into automotive, aerospace, food, marine, machine working, mining, and others.
The need for R&D and technological upgrades is constant regarding grease additives. Regulatory institutes are in-charge of performance and emission standards that are set for fuels and lubricants (greases are classified among them). Manufacturers are required to adhere to these standards. Rapid and constant technological advancements in the automotive and machine working industries result in subsequent need for development of high performance and environmental-friendly greases as well as grease additives.
The grease additives market can be divided based on geography as North America, Latin America, Europe, Asia Pacific, and Middle East & Africa. Asia Pacific is the leader of the market in terms of production, with China being the dominant player in the world.
Some of the key players in grease additives market are Afton Chemical, BASF SE, Clariant, Lubrizol, and Innospec.