US2218132A - Sulphur containing lubricant - Google Patents

Description

Patented Oct. 15, 1940 UNITED STATES PATENT OFFICE Bert E. Lincoln, Waldo L. Steiner,

Byrkit, Ponca City, Okla tinental Oil Company,

poration of Delaware and Gordon D. assignors to Con- Ponca City, Okla, a cor- No Drawing. Application May 2, 1938,

Serial No. 205,531

3 Claims.

Our invention relates to sulphur containing lubricants and more particularly to a lubricant containing a sulphur bearing additional agent, substantially non-corrosive to the newer types of 5 bearing metals now used in present day automotive vehicles.

Automotive engineers are using bearings containing cadmium and copper-lead mixtures as well as high lead content compositions. These 30 new bearing compositions, while possessing cer-' tain mechanical advantages over the old tinbabbitt bearings, are more susceptible to corrosion. Oxidation and decomposition products of the lubricant react with these bearings and often cause failure through corrosion.

One object of our invention is to provide a lubricant containing a new type of sulphur compound which will impart increased film strength to the lubricant while being substantially noncorrosive to the new type bearing metals.

Another object of our invention is to provide a sulphur containing addition agent which is at once a film strength improver and a corrosion inhibitor.

Another object of our invention is to provide a lubricating oil containing a sulphur bearing addition agent which will reduce oxidation, with the resultant sludge and acid formation. I

Another object of our invention is to provide a lubricant having increased oiliness characteristics and color stability.

Other and further objects 'of our inventionwill appear from the following description.

In general, our invention comprises the addition of small quantities of sulphurized olefins of high molecular weight to hydrocarbon oils. As little as .05 of one percent of our new'sulphur compound, added to a lubricant, appreciably increases its resistance to oxidation and corrosive- 40 ness. As much as 20 percent of the compound may be added to a lubricant with beneficial results with respect to its film strength and'oillness properties, although it is seldom that more than 2 percent need be used for a crank case lubricant.

A lubricant containing from 2 to 20 percent makes an admirable cutting oil or an extreme pressure lubricant.

To obtain our sulphurized olefins of high molecular weight we start with a substantially oilfree paraflin wax. By way of examplebut not by way of limitation, we will describe the method of obtaining our'addition agent from a low melting point wax of from 18 to 24 carbon atoms. The

wax is halogenated to a halogen content of from 8 to 12 percent. The crude halogenation mixture will comprise some unchlorinated wax, mostly monochlor wax and some more highly chlorinated waxes. Chlorination of wax lowers its melting point stepwise inversely as the degree of chlorination. A monochlor wax will melt lower than the like unchlorinated wax. A dichlorinated wax will have a lower melting point than the monochloro wax. The unchlorinated wax may be separated readily from the crude chlorination mixture by melting point diflferences, using sweating, or selective solvent extraction at various temperatures.

A solution of the crude chlorination mixture may be formed with acetone. At about F. the chlorinated waxes will be in solution, while the unchlorinated wax will not dissolve and may be separated by settling, centrifuging or filtering.

,The solution may be chilled to precipitate the monochloro wax. Thus the monochloro wax may be separated from the polychloro wax employing the same methods as these outlined for separating unchlorinated wax from the chlorinated wax mixture. The monochlor wax thus obtained is substantially free of unchlorinated waxes or more highly chlorinated waxes and may be converted to the corresponding olefin by removing the chlorine as hydrogen chloride thus producing a double bond. To prepare the olefin, the monochlor wax may be heated for a period of one minute or less to five hours, with one tenth of its weight or more of lime, at temperatures between 200 F. and 500 F. The olefin may be formed by removing the hydrogen chloride by heating alone, although the color of the resulting olefin is darker than when lime is used. After dehalogenation, the lime or other dehalogenating agent is removed from the resulting olefin by the usual means such as by filtering.

The theoretical iodine value for an olefinic hydrocarbon having the formula C25H50 is 72.6. The-iodine value of the olefin prepared as described is about 72. I

It should be pointed out that olefin made as described is a definite type of compound having the structure RC=CR When prepared from a parafiin wax R is an aliphatic group containing 1 to about 20 or more carbon atoms. The slun of the two Rs should be between 10 and 60 carbon atoms. When the olefin is prepared from a wax, a high boiling mineral oil, or mixture of wax and mineral oil, a specific type of structure is always obtained. In sulphurizing this type of compound the sulphur adds on to the double bond and none is substituted for hydrogen, as is proved by the fact that in the sulphurization practically no B23 is formed. This fact makes it possible to prepare a definite type of sulphur compound in contrast to the heterogeneous mixture which is obtained when a cracked petroleum derivative containing many types of unsaturates is sulphurized. The advantages of the former due to its relative purity are obvious.

One hundred parts of the olefin are chemically combined with 10 to 15 parts of elemental sulphur. This is accomplished by heating and stirring at temperatures from 300 F. to 360 F.

Amounts of sulphur and temperatures outside the given ranges may be used with less satisfactory results. The heating is continued until all of the sulphur has chemically combined. A copper strip test on a one percent blend in gasoline, for example, giving a good color will indicate when the reaction has been completed. Improved results are obtained by firstmixing the olefin with about an equal volume of refined mineral oil before sulphurizing. The sulphurized olefin thus prepared is now ready for use in a variety of lubricants such as gear lubricants, extreme pressure lubricants, and cutting oils. It is merely blended with a suitable base oil in proportions of 0.05 to 20 percent or more, depending on the amount of sulphur required in, the lubricant. These blends yield superior lubricants compared to the corresponding blends made from the wellknown sulphurized fatty oils in that they contain no glycerine either free or in combination. Glycerine compounds in a lubricant are prone to cause gumming of mechanical parts and are less stable than the sulphurized olefin lubricants. A further important superiority of the latter is the relatively low viscosity of the blends at low temperatures compared to the viscous blends that result when sulphurized fatty oils or glyoerides are used. We are aware of prior art which describes lubricants containing sulphurized unsaturated hydrocarbons from the cracking of mineral oil. In said art a conglomerate mixture of compounds containing some unsaturates are sulhpurized. It is unlikely that any high boiling olefins are present in this mixture, since it consists of a cracked product and most, if not all, of the unsaturates would therefore be cyclics. On sulphurizing these, some sulphur will enter into chemical combination by hydrogen substitution which is objectionable. The unsaturated, double bonds in a cracked product are not of equal chemical activity therefore there can not be an even distribution of sulphur throughout its mass which is very highly undesirable. In our invention, we sulphurize a relatively pure olefin and obtain a relatively pure compound having constant, definite, and predictable properties. Our product readily lends itself to refining. It does not contain any objectionable components after refining.

When the sulphurized olefin is to be used as i an inhibitor in a crankcase lubricant for protection of the new type bearings, it may be first refined. The sulphurized olefin should be treated to remove the usual traces of 1128 present. This may be done by blowing with an inert gas or other suitable means. (Unremoved HzS is oxidized in the subsequent acid treat to free sulphur and gives a product which will darken a copper strip.) The olefin (or blend of olefin in mineral oil) is contacted with .5 to 3 percent by weight of percent sulphuric acid for 5 to 30 minutes at to F. The sludge is allowed to thoroughly settle and the treated product is transferred to a clean container and neutralized with fuller's earth or the equivalent, such as activated carbon, bauxite, lime or caustic at temperatures between 200 and 275 F. for 5 to 10 minutes. The mixture is filtered to remove the neutralizing agent. The finished product has a color of about 3 A. S. T. M., is odorless, and when blended with a lubricating oil does not affect the color or the emulsion test as do the sulphurized glyoerides.

A. S. T. M. Herschel demulsteam emulsion sibility SAE 10 mineral 30 (perfect) 1620 (perfect). SAE 10 mineral plus .2 per- 30 (perfect) 16%) (perfect).

gent refined sulphurized ole- SAE 10 mineral plus .2 per- 90 (bad) 420 (bad).

cent refined sulphurized lardoil.

sion test and was developed by the General Motors Corporation and is fully described in the literature. It consists essentially of a sump in which the oil is heated to 325 F. The test pieces are half bearing inserts of the cadmium alloy and copper-lead types and are held in a rigid position in' a small chamber. Jets of the hot oil under 10 pounds pressure are impinged against these pieces. The test is allowed to run four hours or until corrosion starts. For a standard test, the mineral oil is blended with alead soap to the extent that the blend contains .05 percent lead oxide. The lead soap accelerates the corrosion rate. The following test shows the effeet of the addition of the sulphurized olefin on corrosion with respect to cadmium alloy and copper-lead bearings.

The manner in which this inhibitor stops corrosion is not known, but the following theory gives a fairly satisfactory explanation. It is a fact that some metallic oxides and soaps have a strong catalytic effect on the oxidation of mineral oil, which in turn gives rise to the formation of corrosive organic compounds. Furthermore, it is known that the metallic sulphides are insoluble in mineral oil. It is assumed, therefore, that as soon as any metals, such as iron from the engine and copper, lead, or other metals from the bearings, start to corrode, they form the relatively inert sulphides instead of the active oxides and soaps, thus slowing down the rate of oxidation of the lubricant. It is obvious then that a sulphur compound to be a good inhibitor must not be too stable or it cannot give up sulphur at a. rate equal to the lubricants tendency to form oxidation products and soaps. Furthermore, it must not be too unstable or it will give up too much sulphur and cause corrosion from the action of free sulphur which would first manifest itself in the darkening of copper parts. The sulphurized olefin of our invention has just the correct degree of stability since it inhibits corrosion but does not darken the copper-lead bearings.

The sulphurized olefin does not only stop corrosion of the new type bearings, but it also reduces the amount of oxidation of the oil. A Standard of Indiana oxidation test, which is fully described in the literature. was run on a base oil and on the same oil plus .2 percent of sulphurized olefin.

SAE 30 min- Hours required to produce-- a g fl 'g g olefin Hours Hours 10 mg. sludge 13. 5 17. 5 100 mg. sludge l. 29. 34. 0 0 neutralization number 7. 0 11. 8 1 0 neutralization number 12. 8 18. 4 1000 true color 7. 2 8.2 2000 true color 16. 2 18. 0

In practicing this invention, the relatively, pure mono-olefin which is obtained from the relatively pure monochlor wax is sulphurized as was stated previously; however, the olefins, diolefins and polyolefins resulting from the dehalogenation of dichlor and polychlor wax or mixtures thereof with each other and unchlorinated wax may be used with some degree of success in preparing a sulphur base for use in a cutting oil, gear lubricant, extreme pressure lubricant, etc., but they are not so satisfactory for crankcase lubricants because of the dimculty of refining them.

Our olefins are characterized by the fact that considerably more sulphur (a total of 20 percent or more) can be made to combine with them by using temperatures up to 450 F., than is obtained by saturating them at 300 to 360 F. with sulphur. This holds true for the mono-olefins as well as for the polyolefins. Prepared this way, they are able to hold in solution additional percentages of elemental sulphur. A sulphur base of this type is well suited for use in cutting oils 55 etc.

The sulphurized olefins described in this invention may be blended with any mineral, synthetic, animal, or vegetable oil to improve resistance to oxidation, with its attendant increase in sludge formation, and tendency to corrode metals.

It isto be understood that the examples hereinabove given are by way of illustration only and not by way of limitation and that the theories advanced with regard to the action of our sulphurized olefins are our conception of what takes place. We do not wish to be bound by the theories but base our claims upon the improved results which are obtained.

It will be understood that certain features and sub-combinations are of utility and may be em-.

ployed without reference to other features and sub-combinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in detailswithin the scope of our claims without departing from the spirit of our invention. It is,

therefore, to be understood that our invention is not to be limited to the specific details shown and described.

Having thus described our invention, we claim: 1. A lubricating oil consisting of a major pro 'portion of a hydrocarbon oil and from ...05 of one percent to 20' percent of a sulphurize d fsubstantially pure olefin, said olefin having the structure R-o=c-R I! t in which R. represents aliphatic groups the sum of the carbon atoms in the R. groups being between and 60, said product derived from petroleum wax by halogenation and dehalogenation.

2. A lubricant consisting of a major proportion of a lubricating base and a minor proportion of a sulphurized substantially pure olefinic hydrocarbon, said olefinic hydrocarbon prepared by dehalogenating a monochloro petroleum wax derivative of 10 to 60 carbon atoms by means of heating said monochloro derivatives with lime or other basic compounds to temperatures of 200 F. to 550 F.

3. A lubricant comprising in combination a major proportion of a hydrocarbon oil and a -minor proportion of an addition agent composed essentially of a sulfurized olefine derived from petroleum wax of'10 to 60 carbon atoms by halogenation, dehalogenation and sulfurization.

BERT H. LINCOIIZIN'. WALDO L. STEINER. GORDON D. BYRKIT.