Biodegradable lubricating grease from ADDINOL

The general basic structure of a biodegradable lubricating grease does not differ fundamentally from the basic structure of conventional mineral oil-based lubricating greases and can be described as a combination of a base oil and a suitable thickener. Various additives (e.g. antioxidant base oils, corrosion inhibitors, anti-wear additives) can also be added for further functionalisation and performance enhancement. The main component of any lubricating grease is the base oil it contains, the proportion of which is typically in the range of 70% to 95%. In order to realise a sufficiently high biodegradability of a lubricating grease, native vegetable oils (e.g. rape seed oil) or synthetic esters are usually used as base oils.

The biodegradability of lubricants is tested in the laboratory in accordance with OECD Guideline 301, which defines six different test methods (A, B, C, D, E and F). The OECD 301 B, OECD 301 C and OECD 301 F test methods are suitable for testing water-insoluble products (such as the biodegradable lubricating greases discussed here). A tested lubricating grease may be considered biodegradable if at least 60% of the theoretically expected carbon dioxide is formed within 28 days under the specified test conditions, an oxygen consumption of at least 60% of the theoretical oxygen requirement is demonstrated or a decrease in dissolved organic carbon of at least 70% can be observed.

The complete biological degradation of a lubricant is carried out by microorganisms (fungi, yeasts, bacteria) in a sequence of several sub-steps. In a first step, fragments of the original starting material are produced, which in turn are metabolised further and further by microorganisms until, at the end of this process, only carbon dioxide, water, inorganic salts and the biomass attributable to the microorganisms remain.