AP634A

AP634A - Lubricant.

Info

Publication number: AP634A
Application number: APAP/P/1996/000802A
Authority: AP
Inventors: Bonis Richardo Alberto De
Original assignee: Engen Petroleum Ltd
Priority date: 1995-04-13
Filing date: 1996-04-11
Publication date: 1998-04-01
Also published as: ZA962705B; AP9600802A0

Abstract

A lubricant composition is disclosed which comprises tall oil and a suitable amount of an

Description

FIELD OF THE INVENTION

This invention relates to lubricants. More particularly, the invention relates to a grease suitable for use in lubricating the moving parts of machines and devices used in confined spaces such as in underground mines and tunnels.

BACKGROUND TO THE INVENTION

A multitude of different lubricants, including greases, are known to the applicant. A lubricant is usually in the form of a composition of which the constituents are carefully selected to play a role in providing the right consistency, viscosity, protection against corrosion, extreme pressure, etc.

Because of the low cost and abundance thereof, mineral oils have been very popular in supplying the bulk of the components required for making lubricants. However, under certain circumstances such as in underground mines where people have to work under hot and humid conditions in confined spaces, toxicity has become an important consideration. In addition, biodegradability of lubricants, once they have been used, has become important in view of modern ore beneficiation technologies which increasingly rely on the use of flotation. The reason is that it has been found that even minor concentrations of lubricants in ore recovered from underground mines can poison flotation cells.

There accordingly exists a need for a lubricant composition which has a low toxicity and which is biodegradable.

AP/P/ 9 6 / 0 0 80 2

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a lubricant composition comprising tall oil and a suitable amount of an organophilic clay which is substantially uniformly dispersed therein.

The tall oil may be crude or distilled. If distilled, a suitable fraction of the tall oil, in terms of viscosity, may be used in the composition. Thus, in order to increase the viscosity of the composition, a tall oil fraction having a high viscosity, such as tall oil pitch, may be used.

Depending on whether whole or undistilled tall oil or only a fraction thereof is used, and furthermore depending on the physical properties of the fraction, in the event that a fraction is used, and in addition, depending on the application for which the lubricant composition is to be used, it may comprise from about 4% to about 12% of the organophilic clay.

It-has been found that high concentrations of organophilic clay within the aforementioned range will tend to yield a lubricant composition of thicker consistency, of which the penetration will be lower, whilst lower concentrations of organophilic clay within the aforementioned range will yield a lubricant composition which is of thinner consistency,

i.e. of which the penetration will be higher. Standard ASTM tests are available for testing properties of greases such as penetration, viscosity, etc.

AP/P/ 9 6 / 0 0 8 0 2

AP 00634

In order to achieve the thickening effect of the organophilic clay, a polar activator may be added to the lubricant composition. Suitable polar activators are propylene carbonate, ketones, alcohols, etc.

Depending upon the consistency required, the polar activator may be present in the composition at a concentration ranging from about 5% by mass to about 15% by mass of the organophilic clay.

In order to prolong the shelf life of the lubricant composition, it may comprise an anti-oxidant at a concentration of from about 0,4% by mass to about 0,8% by mass, based on the total mass of the composition.

Suitable anti-oxidants are strong reducing agents such phenyl- and diphenyl amines. Care should be taken not to add too much anti-oxidant, as this may result in the biodegradability of the lubricant composition, after use thereof, to be detrimentally affected. Thus, depending on the particular need which has to be addressed, a lubricant composition in accordance with the invention can be designed which is optimised both in terms of shelf life and biodegradability.

The lubricant composition in accordance with the invention may also comprise a corrosion inhibitor which may be present in the composition at a concentration of from about 0,4% to about 0,8% by mass, based on the mass of the total composition. The corrosion inhibitor may be selected to protect steel again rust. Alternatively, it could be selected so as to protect other metals against other types of corrosion, where the type of corrosion could vary depending upon the ambient conditions under which the lubricant composition is to be used, and the materials of construction of the specific devices or machines which have to be lubricated.

AP/P/ 9 6 / 0 0 8 0 2

Corrosion inhibitors which are suitable, are compounds such as N-acyl sarkosine, imidazoline derivatives, succinic acid esters, and the like.

In order to improve the extreme pressure characteristics of the lubricant composition in accordance with the invention, it may also comprise an extreme pressure additive. Suitable extreme pressure additives are bismuth carboxylate and lead naphthenate (although the latter has been found to be unacceptable under conditions where low toxicity is of overriding concern).

In a preferred embodiment of the invention, a lubricant composition which is suitable for use as a rock drill grease, comprises:

% Mass / Mass

Organically modified smectite clay (available from

AP/P/ 9 6 / 0 0 8 0 2

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RHEOX under Code Name EA-2356):

from 4,0% to 8,0%

Tall oil pitch from 5% to 50%

Anti-oxidant from 0,4% to 0,8%

Corrosion inhibitor from 0,4% to 0.8%

Extreme pressure additive from 0,5% to 1,0%

Polar activator

10% of the mass of the organophilic clay.

AP 00634

The balance of this composition may be a suitable distilled fraction of tall oil or, alternatively, crude tall oil or a mixture thereof with one or more fractions thereof.

This composition has been found to give good results in lubricating the moving parts of a rock drill machine, yet it is still comparatively inexpensive. It is also biodegradable and non-toxic.

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Claims

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1. A lubricant composition comprising tall oil and a suitable amount of an organophilic clay which is substantially uniformly dispersed therein.

2. A lubricant composition as claimed in claim 1, wherein the tall oil is crude or undistilled.

3. A lubricant composition as claimed in claim 1, wherein the tall oil is a suitable distilled fraction.

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4. A lubricant composition as claimed in claim 3, in which the tall oil fraction is tall oil pitch.

5. A lubricant composition as claimed in any one of the preceding claims, wherein the organic clay concentration varies from 4% to 12% of the mass of the lubricant composition.

r-6. A lubricant composition as claimed in any one of the preceding claims, comprising a polar activator.

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AP 00634

7. A lubricant composition as claimed in claim 6, in which the polar activator is selected from a propylene carbonate, a ketone, an alcohol, or a mixture thereof.

8. A lubricant composition as claimed in claim 6 or claim 7, in which the polar activator is present in the composition at a concentration ranging from 5% by mass to 15% by mass of the organic clay.

9. A lubricant composition as claimed in any one of the preceding claims, comprising an anti-oxidant at a concentration of from 0,4% by mass to 0,8% by mass, based on the total mass of the composition.

10. A lubricant composition as claimed in claim 9, in which the anti-oxidant is a strong reducing agent selected from phenyl- and diphenyl amines, or a combination thereof.

11. A lubricant composition as claimed in claim 9 or claim 10, in which the anti-oxidant concentration is selected such as to optimise the lubricant composition in terms of shelf life and biodegradability.

12. A lubricant composition as claimed in any one of the preceding claims, comprising a corrosion inhibitor which is present in the composition at a concentration of from 0,4% to 0,8% by mass, based on the mass of the total composition.

13. A lubricant composition as claimed in claim 12, wherein the corrosion inhibitor is selected such as to protect steel against rust.

14. A lubricant composition as claimed in claim 13, wherein the corrosion inhibitor is selected from N-acyl sarkosine, an imidazol derivative, a succinic acid ester, or a combination thereof.

15. A lubricant composition as claimed in any one of the preceding claims, comprising an extreme pressure additive.

16. A lubricant composition as claimed in claim 15, in which the extreme pressure additive is selected from bismuth carboxylate and lead naphtenate.

AP/P/ 96/00802

17. A lubricant composition which is suitable for use as rock drill grease, comprising: an organically modified smectite clay in a concentration of from 4% to 8% by mass, tall oil pitch in a concentration of form 5% to 50% by mass, an anti-oxidant in a concentration of from 0,4% to 0,8% by mass, a corrosion inhibitor in a concentration of from 0,4% to 0,8% by mass, an extreme pressure additive in a concentration of from 0,5% to 1% by mass and a polar activator in a concentration of approximately 10% of the mass of the organophilic clay.

18. A lubricant composition as claimed in claim 17, comprising in addition, a tall oil component selected from a suitable distilled fraction of tall oil, a crude tall oil, or a mixture thereof with one or more fractions thereof.