Greases

Lubricating base oils for greases 

The base fluid component of grease must be able to perform many functions. For example, the grease is required to have excellent lubricating properties and good solubility characteristics, enabling it to solubilise performance enhancing additives. The base oil should be matched to the thickener system to avoid detrimental effects through solubilisation.

A lubricating base fluid may also be required to have the following attributes:

• Highly biodegradable/renewable
• Able to withstand extreme temperatures
• Suitable to meet food contact criteria.

The base oil component of the grease must be able to perform many functions. For example, the grease is required to have excellent lubricating properties and good solubility characteristics to enable it to solubilise performance enhancing additives. The base oil should be matched to the thickener system to avoid detrimental effects through solubilisation.

We offer base oil suitable for: 

• High temperature applications
• Low temperature applications
• Food contact applications
• Biodegradable applications.

Base oil thickeners (metallic soaps)

We provide fatty acids for manufacture of standard and complex soaps. Our range includes Priolene™ 6907 (Oleic acid), Prisorine™ 3501 (Isostearic acid) as well as Crodacid™ DC 1195 (azelaic acid).

What are grease thickeners? 

Grease thickeners are substances that form the basis of a grease when combined with a suitable base oil and act to increase the consistency. Greases are solid to semi-solid lubricants that offer unique physical properties compared to oils.  

A typical grease viscosity is measured by consistency in a standard numbering system created by the National Lubricant Grease Institute (NLGI) and range from a NLGI 000 semi-fluid grease to a firm block NLGI 6 grease. Grease thickeners give greases their useful, viscous properties by creating the lattice structure and are conventionally metallic soaps with long chain fatty acid, creating a solid or semi-solid end product. Soaps are typically fibrous and will vary in thickness and oil solubility and these variations are exhibited in the final properties of the grease.

What are the main types of soaps available? 

Standard soaps 

Soaps are salts formed in the reaction between a strong base and a fatty acid. A commonly used example is lithium stearate, which is created by the reaction of lithium hydroxide with stearic acid. Metallic soaps impart the physical characteristics needed for the grease, including:

• High viscosity (to prevent drip and to convey staying power) 
• Physical stability (high viscosity, even at high shear rates)
• Temperature stability.  

The base oil is blended through the soap and the soap fibres act like sponges, holding the base oil in place, allowing it to be released during use.  

Complex soaps 

Instead of just reacting lithium hydroxide with stearic acid to create lithium stearate, additional positive properties of a grease thickening soap can be created by utilising 12-hydroxystearic acid with the addition of a complexing agent during soap manufacturing. Under high shear stress and loading, the complexed molecule helps to maintain the grease structures as well as maintaining consistency at high temperature stability. 

Surface repair additives with REWITEC™ 

REWITEC, a Croda subsidiary, are experts in surface friction and wear. REWITEC has developed a series of lubricant oil and grease additives using their patented silicate technology. Using REWITEC GR400 grease in extreme applications, like wind turbine bearings, can repair existing damage and prevent new damage from occurring.