Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic -co- compound
Patent
1997-03-04
1998-05-05
Medley, Margaret
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic -co- compound
508491, C10M14102
Patent
active
057474346
DESCRIPTION:
BRIEF SUMMARY
The objects of the present invention are a process for preparing a synthetic ester from a vegetable oil by means of lipase enzymes, and lubricants which contain a synthetic ester prepared by said process.
Natural fats and oils have been used as lubricants already for thousands of years. With industrialization mineral based lubricants came also to the market. The applications of lubricants and thus also the requirements set for them have changed and developed with the advance of technology. Various types of synthetic esters and lubricants containing the same have been developed to meet the new requirements.
The purpose of a lubricant is to minimize friction and wear of metals. Lubricants are developed according to the use and they consist of a base fluid and additives improving the lubricative properties. With the development of technology, lubricants are used under more and more severe conditions, such as at very low or very high temperatures (e.g. the turbine engines of aeroplanes). At the same time biodegradability, non-accumulation to the environment, non-toxicity and the use of renewable raw materials have emerged as new requirements. The use of biodegradable lubricants is of particular importance in the machines and devices used in the fields of agriculture, forestry and building, as the oil used may be left in the environment.
By the synthetic esters developed as lubricants are meant esters prepared from mono-, di- or trialcohols and mono- or dicarboxylic acids by known esterification and transesterification methods. The conventional chemical process comprises combining all the reactants and letting them react in one stage. The reaction may be carried out in the presence of catalysts, such as acids, bases or metal oxides. In addition to chemical agents, also lipase enzymes can act as catalysts of transesterification reactions.
Lipases (triacylglycerol acylhydrolase; EC 3.1.1.3) belong to the esterase enzyme group, and fats and oils are their natural substrates. Several microbes (yeasts, molds, bacteria) secrete in their growth media lipases by means of which lipids decompose into nutrients of the microbe. Lipases catalyze the hydrolysis reactions of oils and fats but under suitable conditions they also catalyze the synthesis and transesterification of tri-, di- and monoglyceride esters (Yamane et al., J. Am. Oil Chem. Soc. 64, 1987, 1657-1662).
On the basis of their specificity, lipases are divided into three groups, nonspecific, 1,3-specific and fatty acid specific lipases. Nonspecific lipases are produced by for instance the yeast Candida rugosa (ex. cylindracae) and the bacteria Corynebacterium acnes and Staphylococcus aureus. Nonspecific lipases release fatty acids from all three positions of a triglyceride. According to their name, 1,3-lipases release fatty acids from positions 1 and 3 of triglycerides. These lipases are produced by for instance the molds Aspergillus niger, Mucor javanicus, Mucor miehei and Rhizopus arrhizus as well as by the yeast Candida lipolytica. The fatty acid specific lipases release only certain fatty acids from triglycerides. Mucor miehei, for example, produces also a lipase which in addition to 1,3-specificity is also specific to fatty acids with 12 carbon atoms. However, the specificity is not absolute.
The structure of the synthetic ester used has a profound effect on the stability of the lubricant. Esters decompose by the effect of heat and/or oxygen. It is known to increase the thermal stability of synthetic esters by using in the preparation no beta hydrogen alcohols. Oxidative properties on the other hand can be improved by deuteration of esters.
Synthetic esters intended for a lubricative use are classified by structure as monocarboxylic acid, dicarboxylic acid, polyol and complex esters. Due to their low viscosity and high volatility monoesters are poorly suitable as lubricants. Polyol esters are chemically more stable than for example diesters, due to the structure of the polyols used in the preparation of said esters wherein no hydrogen atom is attached to th
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Patent Abstract of Japan, vol. 12, No. 191, C-501, Abstract of JP, A, 62-296884 (Chiyoda Chem. Eng. & Constr. Co. Ltd.), 24 Dec. 1987.
Lamsa Merja
Linko Pekka
Linko Yu-Yen
Uosukainen Esa
Medley Margaret
Raisio Yhtyma Oyj
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