298 94 307/02 Untersuchungen zum Stand der Umsetzung des ...

Teil 3 Seite 10-3
After purification, transesterification takes place. Alcohol types with different chain
lengths are to be utilised systematically here. Initially, the utilisation of methanol, ethanol,
iso-propanol, iso-butanol and 2-ethyllhexanol is planned. These types of alcohol represent
an influencing quantity in terms of both product properties (e.g. viscosity), as well as proc-
essing costs. Subsequent market prices can be influenced on this basis.
Additionally, the possibility of determining how the range of products can be extended
exists through transesterification with other long chain types of alcohol or also polyols. As
a result of the expected higher viscosity of these esters, it should be possible also to pro-
vide hydraulic or bed track oils for production machinery.
In order to separate undesired unsaturated fatty acid esters, distillation is to be carried
out subsequently. This is necessary, since these substances can negatively influence the
oxidation stability and therefore the life-span of the cooling lubricant. In this context, it
must additionally be tested to what extent hydration can improve the quality of the ester.
Economics
Despite these technological advantages, these substances are not yet accepted in prac-
tice to the extent desired. The main reason for this is the high price of these substances in
comparison to mineral oil. These high input costs during the refilling of a cooling lubricant
plant are currently not yet sufficiently compensated for by expected savings potential, e.g.
through extended tool life. This is particularly apparent from Figure 10-2. Here, the costs
relating to refilling, the savings potential, as well as the resultant replacement investment
in dependence on ester costs are illustrated using a practical example.