Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic phosphorus compound – wherein the phosphorus is...
Patent
1998-01-23
1998-10-20
Johnson, Jerry D.
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic phosphorus compound, wherein the phosphorus is...
C10M13704, C10M13712
Patent
active
058246282
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This application is a Rule 371 of PCT/GB96/01173 filed May 16, 1996.
This invention relates to compositions suitable for use as lubricants, more particularly for use as slideway lubricants.
2. Description of Related Art
Machine tools are frequently required to manufacture articles to very fine tolerances, for example the tolerance in the manufacture of a cam shaft may be only about one micron. For this purpose the machine tool must be accurately positioned. Slideway lubricants are the lubricants that are used to lubricate the surface on which the machine tool is mounted to facilitate the accurate positioning required.
Esters of phosphoric acid have been previously proposed for use as friction reducing agents in slideway lubricating compositions, for example the mono and di amyl esters of phosphoric acid have been described in combination with fatty materials such as sulphurised esters.
Previously, it has been necessary for these fatty materials to be present in significant amounts, typically 1% to 5% by weight and the esters of phosphoric acid to be present in amount from 0.05 to 1% by weight of the lubricating composition. It is desirable to be able to reduce the amounts of additives, not only for economic reasons, but because they can contaminate the metal working fluid.
SUMMARY OF THE INVENTION
The present invention provides a solution to this problem by providing a composition containing a phosphonate ester and an acid ester phosphate which enables the required low friction properties to be achieved at lower levels of additive than previously. According to the present invention there is provided a lubricating composition comprising:
(a) a base oil,
(b) from about 0.05, preferably from about 0.1, to 0.6% by total weight of (a), (b) and (c) of an acid ester of phosphoric acid of formula: ##STR2## where R.sub.1 is a monovalent organic group containing from 3 to 30 carbon atoms and R.sub.2 is hydrogen or a monovalent organic group containing from 3 to 30 carbon atoms and
(c) from 0.1, preferably from 0.25, to 0.7% by total weight of (a), (b) and (c) of a phosphonate ester of formula: ##STR3## where R.sub.3 and R.sub.4 are independently monovalent organic groups containing from 1 to 10 carbon atoms and R.sub.5 is a monovalent organic group containing from 4 to 30, preferably 10 to 24 carbon atoms.
The base oil can be any lubricating oil whether natural or synthetic. The natural oils include paraffinic, naphthenic and aromatic oils or mixtures thereof. Among the synthetic oils are polyalphaolefin fluids, polyoxyalkylenes, polyacetals, polysiloxanes and esters.
The esters are those made from polyhydric alcohols and monocarboxylic acids such as from pentaerythritol or neopentyl glycol and its homologs and aliphatic monocarboxylic acids having from 4 to 9 carbon atoms. Also useful are those esters made from dicarboxylic acids eg sebacic acid and monohydric alcohols eg 2-ethylhexanol. In the acid esters of the above formula R.sub.1 and R.sub.2 (when not hydrogen) are preferably an aliphatic group, for example, an alkyl or alkenyl group which is preferably straight chain and preferably contains from 5 to 20 carbon atoms. R.sub.1 is conveniently the same as R.sub.2.
Both the mono and diesters are suitable and mixtures of the two may be used. A particularly convenient ester is a mixture of the two forms in approximately equimolar proportions eg from 40:60 to 60:40 for example a mixture of the di and mono n-heptyl acid phosphates. In the phosphonates of the above formula preferably R.sub.3 and R.sub.4 are each an aliphatic group, for example containing from 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms. R.sub.5 preferably contains more carbon atoms than R.sub.3 or R.sub.4 and is also preferably an aliphatic group and conveniently contains from 12 to 24 carbon atoms, more preferably 15 to 20 carbon atoms.
Preferably R.sub.5 contains no aromatic substitution and is most preferably an alkyl group which is desirably straight chain. Some braching can b
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Coates David
Gelder Andrew
Castrol Limited
Johnson Jerry D.
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