Compositions – Electrolytes for electrical devices
Patent
1992-12-24
1995-01-31
Niebling, John
Compositions
Electrolytes for electrical devices
C10M14108
Patent
active
053856821
DESCRIPTION:
BRIEF SUMMARY
This invention relates to grease compositions, more especially to grease compositions exhibiting flame retardant properties.
Greases containing metal soap thickeners, for example lithium, calcium or sodium soaps, are well known for industrial and other applications. With increasing health and safety standards, there is a need to improve the flame retardant properties of these greases.
Accordingly, the present invention provides a grease composition comprising: mixture of two or more thereof: and additive comprising an oxide, carbonate, bicarbonate, hydrogen carbonate or sulphate of an alkali metal or alkaline earth metal, or a mixture of two or more thereof.
It has been found that by including the inorganic additive (c), the flame retardant properties of the grease can be significantly enhanced.
The alkali or alkaline earth metal employed in the additive (c) (hereafter the "flame retardant additive" may be for example, lithium, sodium, potassium, magnesium or calcium. Calcium or potassium is preferred.
The salt of the flame retardant additive is preferably an oxide, carbonate, hydrogen carbonate, or sulphate. Examples of preferred compounds include calcium oxide, potassium carbonate, potassium hydrogen carbonate and potassium sulphate.
Whilst the flame retardant properties of the grease can be improved by the addition of a single flame retardant additive, it has been found surprisingly that when a mixture of two or more of the additives are employed, the additives act synergistically and the flame retardant properties achieved are greater than those using the same amount of each additive individually. Thus in a preferred embodiment of the invention the grease composition contains a mixture of two or more, preferably two, of the above flame retardant additives.
This bicomponent flame retardant additive mixture is preferably a combination of calcium and potassium compounds, for example calcium oxide and potassium carbonate, calcium oxide and potassium hydrogen carbonate, or calcium oxide and potassium sulphate.
The amount of the flame retardant additive incorporated in the grease depends upon, for example, the intended purpose of the grease as well as the composition of the grease. In general, the higher the proportion of the additive the greater the flame retardant properties. However, an excessive amount of additive can cause wear, and so generally from 2 to 15%, preferably from 4 to 11%, is used by weight based on the total weight of the composition. Where the flame retardant additive is a bicomponent mixture, it usually comprises 1 to 7% by weight of each component.
The thickener (b) employed in the grease composition according to the invention may be a simple or a complex soap of lithium, calcium or sodium, preferably lithium or calcium. Most preferably the thickener is either a simple lithium soap, a complex lithium soap or a simple or complex calcium soap. The amount of thickener is generally from 2 to 30%, more preferably 5 to 20%, by weight based on the total weight of the composition.
Where the soap is a simple lithium soap, it is preferred that the soap comprises a lithium soap of C.sub.12 to C.sub.24 hydroxy fatty acid more preferably a C.sub.16 to C.sub.20 hydroxy fatty acid. A particularly preferred hydroxy fatty acid is hydroxystearic acid, for example 9-hydroxy-, 10-hydroxy-, or 12-hydroxystearic acid, more preferably the latter. Ricinoleic acid, which is an unsaturated form of 12-hydroxystearic acid having a double bond in the 9-10 position, can also be used. Other suitable hydroxy fatty acids include 12-hydroxybehenic acid and 10-hydroxypalmitic acid.
Where the soap is a complex lithium soap, it preferably comprises a lithium soap as defined above for the simple lithium soap and at least one other lithium compound. This other lithium compound is advantageously either a lithium soap of a C.sub.2 to C.sub.12 aliphatic dicarboxylic acid or a lithium salt of boric acid, or a mixture of both.
Where the other lithium-containing compound is an aliphatic dicarboxylic acid, the proportion of dicarbo
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Hutchings Timothy
Pilgrem Kathryn M.
Exxon Research & Engineering Co.
Niebling John
Takemoto James H.
Wong Edna
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