US2262019A - Lubricant - Google Patents

Description

Patented Nova 11, 194i 2,262,019 LUBRICANT Bert H. Lincoln and Gordon D. Byrkit, Ponca City,'0kla., assignors to Continental Oil Company, Ponca City, Okla, a corporation of Delaware No Drawing. Application May 26, 1939, Serial No. 275,910

5 Claims.

Our invention relates to lubricants, and more particularly to lubricants containing addition agents which greatly increase their resistance to oxidation and the formation of corrosive products during use.

Present-day mechanical devices require lubricating oils of high film strength and of high oiliness characteristics and of low tendency to oxidize during use. It has been found that the modern hydrocarbon lubricants of highest quality are deficient in these three very important characteristics. These three properties are of vital importance conditions of thin film lubrication where the lubricant has been squeezed from between the friction surfaces because of high pressure, slow speeds, exposure of large surfaces of oil to the action of atmospheric oxygen, and other causes. It will be obvious that the viscosity or the body of the lubricant plays no part in this type of lubrication and that the oil film must have a very highfilm strength and possess high oiliness value to prevent rupture of the lubricant film and to keep the coefficient of friction as low as possible. The oil must resist oxidation when these films are heated in the presence, of atmospheric oxygen as they are in use. Y

Mechanical devices are being designed for I higher pressure operation and the film strength of the best quality straight hydrocarbon lubricant has been found to be too low. It will be obvious that our invention which provides a means of improving the film strength of these lubricants is of great importance to the art of lubricant manufacture and to the designer and fabricator of mechanical devices.

Substantially all machines operate in part or at times totally under conditions of boundary or thin film lubrication, under which conditions the oiliness or unctuosity of the lubricant is the first and primary requisite of eiiicient operation. Those skilled in the art of lubricant manufacture or machine manufacture will readily appreciate the value of our invention which improves the oiliness of these otherwise high-quality lub icants. Furthermore, sludge and acid are especially deleterious under conditions of thin film lubrication. The sludge is not a lubricant in any sense of the word, and the soluble acid is particularly corrosive to bearing metals such as cadmium-silver, copper-lead, and the like.

In starting idle mechanical equipment which is lubricated by oil from a sump by pumping or circulating the lubricant, there is always a short period of time inwhich the rubbing surfaces operate under conditions of dry friction, if ordinary hydrocarbon lubricants are used. With dry friction, the wear on friction surfaces is extreme; and during cold weather when the lubri cant is sluggish or during periods when the lubricating system is not functioning properly, rubbing surfaces may not only sufler considerable wear but may be damaged to the point where they must be replaced. The product of our invention has the very important property of reacting with the metal surfaces, penetrating or being adsorbed thereon and leaving a film of lubricant of high oiliness character which remains on the metal surface irrespective of the length of time the machine has been idle.

This high oiliness film gives very even and smooth operation, which may be easily discerned by the experienced operator and lubricating engineer, and confirmed by known testing devices.

When the hydrocarbon lubricants are diluted with unburned fuel or with other light hydrocarbone, the small degree of oiliness of the original hydrocarbon lubricant is greatly decreased We have found that the addition of the products of our invention to hydrocarbon lubricants more than compensates for the loss in oiliness and load-carrying ability from dilution,

It is well known that, in order to obtain lubricants which are preeminently satisfactory from the standpoint of resistance to oxidation in use, it is necessary to refine the oil thoroughly and then to add an oxidation inhibitor. The thorough refining may consist of extensive and heavier acid treatment or solvent treating so as to remove a considerable part of the oil and leave only the most stable portion. Such drastic refining is necessary in order to obtain stability with respect to sludge formation, but the oil is then subjectto easy oxidation to form soluble acids and other corrosive materials. This can be prevented by the addition to the refined oil of small amounts of materials which either prevent the formation of these corrosive products or by some action render them inert.

Many of these addition agents are effective when added to poorly refined or even wholly unrefined lubricants. These agents may then be substituted in whole or in part for the usual refining processes.

, One object of our invention is to provide a lubricant containing improved inhibitors of oxi dation and corrosion.

Another object of our invention is to provide a lubricant containing film strength improving compounds.

Other and further objects of our invention will appear in the course of the following description.

In general, our invention contemplates the addition of hydrocarbon oils of small amounts of certain heterocyclic oxygen compounds containing in a heterocyclic ring at least one atom of oxygen and at least one other atom of an element of group .VI of the periodic table. Compounds answering this description usually provide a combination of advantages when blended in lubricating oils. The ring oxygen confers oiliness, the ring sulfur inhibition of oxidation and precipitation of metallic compounds and halogens when present confer film strength. Furthermore, there is an unexpected enhancement of these eflects due to the presence in the same ring of these elements one on the other. Thus oxygen and sulfur in the same heterocyclic ring are particularly advantageous. When halogen is attached to a carbon of the heterocyclic ring it' is more effective as afilm strength improver than when it is attached to a ring containing carbon only as ring members. The heterocyclic compounds containing two oxygen atoms in a ring are particularly advantageous when improved oiliness is desired. These compounds chlorinated are effective for improving film strength. When oxygen and sulfur are both present in the heterocyclic ring the compounds are especially useful as oxidation inhibitors.

Some of these heterocyclic compounds, containing in a ring at least two elements of group VI of the periodic table and including one or more oxygen atoms, which may be used in accordance with our invention are:

. Heptaldehyde glycol acetal.

. Heptaldehydepropylene glycol acetal.

. Propylene glycol carbonate.

. Chloralide (trichloroethylide lactate).

. Trichloroethylidene trichlorolactate.

. Chlorosafrol.

. Chloropiperonal.

Thiocarbonyl monothiopyrocatechol. 9. 1, 2-benzylidene glycerol.

10. 1,'2-benzylidene glycerol benzoate.

11. 1, 2-benzylidene glycerol o-chlorobenzoate.

12. Methylh'exylketone ethylene glycol acetal.

13. Hexachlorodioxane.

14. Tetrachlorodioxane.

15. Dichlorodioxane.

16. 1, 2-diethoxydioxane.

1'7. Dimethyldichlorodioxane.

18. 1, 3-benzy1idene glycerol.

19. 1, 3-benzylidene glycerol o-chlorobenzoate.

20. 2-octadecyl, 1, 3 benzylidene glycerol.

21. Chlorinated 2-pentacosyl 1, 3-benzylidene glycerol.

22. Diamylthloxane.

23. Chlorobenzyl thioxane.

24. Phenoxthin.

25. Di-pentacosyl phenoxthin.

26. Dichlorophenoxthin.

27. Safrol.

28. Piperonal.

29. Naphthodioxane. I

30. Tetrachloronaphthodioxane. Any of these compounds or other members of the classes represented or their derivatives within the limitations set forth may be used within the scope of our invention. Each of these compounds is to be considered an example of our invention when blended in an oil of lubricating viscosity.

It is to be understood that in practicing our invention, oil-soluble compounds of the type described are to be selected. Some of the examples described have only limited solubility in hydrocarbon oils. It is to be remembered, however, that, because of their great efliclency, extremely small amounts are often eifective. Thus we may use as little as 0.001 per cent of some of these compounds, and it will be seen that a fairly insoluble material may dissolve to a suflicient extent to be satisfactory for our purpose. In general, more than 0.001 per cent of our addition agents are used, and we may add one, two, or even five per cent or more. 4

Furthermore, it is'well known that different types of oils have different capabilities of dissolving a given material. For some purposes therefore, we prefer parafiinic. asphaltic, naphthenic or mixed base lubricants. Anothermethod of obtaining a satisfactory mixture of addition ag'ent.with the hydrocarbon oil is the use of a. mutualsolvent to bring the addition agent into solution. Alternatively, peptizing agents may be added to maintain the compounds in permanent suspension.

Many of the more difiicultly soluble materials are rendered more soluble by the introduction of alkylgroups, particularly those containing four or more carbon atoms. The isoamyl octyl, lauryl, and octadecyl radicals and radicals from parafiin wax greatly increase the solubility of organic compounds in oil. One or more of such groups may be introduced as required.

The selection of a particular compound or compounds to be used as an addition agent to the hydrocarbon oil is to be made considering the" use to which the blend is put. Thus, if water is likely to be present during use, a compound or combination of'compounds is selected which isnot aifecte'd by water. If a particular added compound proves too volatile for its application, a higher boiling compound should be used and the more volatile compound used for blending in a hydrocarbon oil intended for duty at lower temperature. ln f'general, for-crankcase lubricants, we prefer to use compounds having vapor pressures of less .than atmospheric at 250 F. Such details of practice will be apparent to any one skilled in the art. 7

By oil having lubricating viscosity, in the appended claims, we meanto include the so-called mineral oils and various hydrogenated, polymerized and otherwise synthetically treated oils, such as voltolized oils, aluminum chloride treated oils, and the like. Furthermore, the lubricating oil may consist in whole or in part of animal or vegetable oils such as castor'oil, lard oil, shale oil, corn oil, cottonseed oil, and the like.

It is sometimes advantageous tocombine more than one of these compounds in a blend to obtain particular properties. We accomplish this by mixing two or more of these compounds together and blending the mixture with the hy drocarbon -oil or by blending one in the hydrocarbon oil, blending the second into this mixture, and so on until the composition is complete.'

The various heterocyclic compounds usually improve both the film strength and oxidation characteristics of the hydrocarbon oil. For example, the sludging tendencies may be decreased y as li tle 8.5.0.001 per cent of our compounds. The oxidation characteristics of lubricants are very important, and these are markedly improved by our compounds. The ability to reduce friction is another feature contributed to lubricants by some of our compounds.

It may be desirable to include in one and the same blend based on a hydrocarbon oil, in addition to the addends here described, other addends for specific purposes. Thus, we may add a pour point depressor such as a naphthalenechlorwax condensation product and a viscosity index improver such as certain resins or polymerized hydrocarbons in addition to our compounds. We may add various sulfur or halogen compounds or compounds containing both of these elements. Halogenated oxygen-bearing ring or chain compounds such as chlorodiphenylene oxide, methyl dichloro stearate and the like;

. lic soaps.

Our addends are admirably adapted for use in lubricating oils of al1 types including those designed for use in automotive crankcases, Diesel oils, and any other oils of lubricating viscosity. Furthermore, our addends are advantageously blended in gasoline and other petroleum fuels either directly or after being blended first in a lubricating oil and then added to the fuel. Soapthickened lubricants of all types ranging from those showing only a slight increase in viscosity over that of the mineral oil alone to the semisolid and solid greases containing fifty per cent or more of soap are amenable to treatment according to our invention. In making these greases, the usual soaps such as sodium stearate, aluminum stearate, calcium soaps of lard oil and the like, may be used. Various other thickening ingredients or materials for other purposes such as dichlorostearic acid, yarn, hair, graphite, glycerol, water, lamp black, mica, zinc dust, litharge and the like, may be used,

It will be understood that certain features and subcombinations may be employed without reference to other features and combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in detail within the scope of our claims without departing from the spirit of our invention. It is, therefore, to be understoodthat our invention is not to be limited to the details described.

Having thus described'our invention, We claim:

1. A lubricant comprising in combination a major proportion of oil of lubricating viscosity and a minor proportion of a compound containing two oxygen atoms in a heterocyclic ring.

2. A lubricant comprising in combination a major proportion of oil of lubricating viscosity and a minor proportion of chlcralide.

3. A lubricant comprising in combination a major proportion of oil of lubricating viscosity and a. minor proportion of hexachlorodioxane.

4. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion of chlorosafrol.

5. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion of a halogenated compound containing two oxygen atoms in the heterocyclic ring.