Compositions – Preservative agents – Anti-oxidants or chemical change inhibitants
Patent
1994-05-09
1997-10-28
Gibson, Sharon
Compositions
Preservative agents
Anti-oxidants or chemical change inhibitants
252407, 508465, 508476, 508496, 508486, 508495, 508500, 508506, 508508, 508510, 508512, 508513, 508262, 508279, 508280, C23F 1114, C23F 1112
Patent
active
056815069
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/GB93/02218 filed Oct. 28, 1993.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a corrosion inhibiting lubricant composition.
2. Discussion of the Prior Art
Corrosion can be a serious problem in the operation and storage of aircraft gas turbine engines, particularly those which are operated in a maritime environment. The effects of corrosion in such gas turbine engines as well as other types of engine, are very costly in terms of servicing, replacement of parts, engine downtime and man/woman hours. In consequence, there is a demand for a lubricant which will substantially reduce corrosion in gas turbine engines and therefore the consequential serious effects thereof as mentioned above.
The United States Navy has recently revised their Military Specification MIL-L-23699D, the revised version of which is designated XAS-L-5724, which specifies the requirements to be met by a lubricating oil for gas turbine engines in order to achieve a higher standard in anti-corrosion properties which is seen as an important goal in view of the serious problems referred to above.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide a corrosion inhibiting lubricant which meets the corrosion protection test designated as ARP 4249 (specified in XAS-L-5724) and DERD Method 18 (specified in DERD 2458).
This objective has been achieved by the compositions of the present invention.
According to the present invention there is provided a corrosion inhibiting lubricating composition comprising R.sup.1 is a tolyl, phenyl, xylyl, alkyl or cycloalkyl group, the alkyl or cycloalkyl group having up to 10 carbon atoms; ##STR4## wherein x+y+z is an integer in the range-from 2 to 22 inclusive and where at least one of the groups R.sub.1 to R.sub.5 is a carboxylic acid group and the remaining groups R.sub.1 to R.sub.5 are selected from alkyl, hydroxy, carbonyl, nitro, amino, carboxyl, hydrogen, or alkyl derivatives thereof, where alkyl is a short chain of up to 5 carbon atoms; or a dicarboxylic acid of one of the three formulae ##STR5## wherein R'.sub.1 is --COOH alkyl, hydroxy, carbonyl nitro, amino, hydrogen, or alkyl derivatives thereof; R'.sub.2 is --COOH; and n is an integer from 1 to 4 inclusive; acid which is optionally sulphurised in an amount which may be up to 35% by weight; or an ester of such an acid; and ##STR6## where R".sub.1 is --COOH or alkyl derivatives thereof, or short chain alkyl of up to 5 carbon atoms; n is zero or an integer between 1 and 3 inclusive; and R".sub.2 is hydrogen, morpholino, alkyl, amido, amino, hydroxy or alkyl or aryl substituted derivatives thereof; or a triazole selected from 1,2,4 triazole, 1,2,3 triazole, 5-anilo-1,2,3,4-thiatriazole, 3-amino-1,2,4 triazole, 1-H-benzotriazole-1-yl-methylisocyanide, methylene-bis-benzotriazole and naphthotriazole.
In component (d) above the bicyclic structural formula is intended to indicate that the group(s) R.sub.2 may be attached to either or both aromatic rings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The neutral liquid polyolester which forms the base stock of the lubricating composition of the present invention may be made from C.sub.5 to C.sub.12 monocarboxylic acids esterified with polyols or polyol ethers, such as neopentylglycol, dimethylolpropane, trimethylolpropane, pentaerythritol or dipentaerythritol. These are conventional synthetic ester base stocks. Preferred esters are those which are described in U.S. Pat. No. 4,826,633.
The aromatic amine antioxidant which forms component (b) of the composition may be present in a range of 0.5 to 5% by weight of the composition. Preferably up to three aromatic amine antioxidants are included, more preferably two, and the antioxidants are more preferably included in the range of 1 to 3% of the weight of the composition. The aromatic amine antioxidants which are employed in the present compositions are those conventionally included in lubricant compositions. Suitable examples are mono-octylphenylalphanaphthylam
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"Qualified Products List of Military Specification MIL-L-23699 Lubricating Oil, Aircraft Turbine Engines, Synthetic Base Nato Code Number 0-156": QPL-23699-17, Jun. 30, 1995.
"Mitary Specification, Lubricating Oil, Aircraft Turbine Engine, Synthetic Base, Nato Code Number 0-156": MIL-L-23699E 25 Aug. 1994.
"Military Specification XAS-L-5724 Lubricating Oil, Aircraft Turbine Engine, Corrosion Inhibiting, Synthetic Base": X45-L-5724, Mar. 20, 1992.
Edwards Mark Anthony
Markson Andrew Jonathan
Pragnell John William Anthony
Castrol Limited
Fee Valerie
Gibson Sharon
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