US2113811A - Sulphurized oils - Google Patents

Description

Patented Apr. 12, 1938 UNITED STATES SULPHURIZED OILS aware No Drawing. Application December 23, 1936, Serial No. 117,901

4 Claims.

Our invention relates to sulphurized oils and more particularly to lubricants containing a specific class of sulphur containing compounds. This application is a continuation in part of our 5 copending application, Serial No. 1l,588, filed March'18,1935.

In our copending application, we have disclosed an improved type of sulphurized oil prepared by adding to a hydrocarbon oil a dihydric '10 or monohydric ester of an unsaturated organic acid which ester has been sulphurized. In said application, the value of a 'sulphurized oil made in accordance with our application for use in cutting lubricants, extreme pressure lubricants and crank case lubricants was pointed out. Sulphurized oils made by adding sulphurized glycerides. or sulphurized vegetable or animal oils to lubricants have long been known but these oils do not possess the advantages of oils compounded by the use of sulphurized dihydric and monohydric esters. The dvantage of oils compounded with monohydric or dihydric esters arises from the fact that no derivatives of glycerine are present, which derivatives will break down during use, liberating glycerine and therefore will cause gumming and sludging which is deleterious, especially in case of internal combustion engines where high' temperatures and'pressures are involved, which will readily facilitate gumming and 30. sludging. v

' Lubricating oils prepared with monohydric and dihydric esters have the further advantage of being less viscous than those prepared by sulphurized glycerides. Moreover, the viscosity does not increase as rapidly on long time heating with sulphurized monohydric and dihydric ester. This is very. important in commercial lubricants.

Higher speeds and greater bearing pressures in modern internal combustion engines have made #9 it necessary for automotive engineers to develop improved bearings. Modern bearings which have resulted from this improvement are of three general types, namely those comprising the cadmium alloys, those comprising the mixtures of copper and lead together with small amounts of other metals, and alloys containing a high perce'ntage of lead. While these new bearing materials are capable of withstanding higher pressures and greater speeds than the old Babbitt bearings,- they are more susceptible to corrosion resulting from the action of oxidation products of the lubri- One object of our invention is to provide a sul- 'ssphurized lubricant which ,will inhibit corrosion with respect to the new type of soft metal bearmgs.

Another object of our invention is to provide a lubricant containing a small amount of sulphurized monohydricor dihydric esters, which 5 lubricant will not be corrosive to bearing metals of the so-called soft metal alloy class but which will nevertheless be sufflcienty chemically active to precipitate objectionable compounds of such metals as sulphides.

Another object of our invention is to provide a lubricant possessing a high degree of oiliness.

Another object of our invention is to provide a lubricant which will possess a decreased rate of oxidation. i

Another object of our invention is to provide a lubricant of decreased sludging characteristics.

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

We have pointed out in our copending application, Serial No. 11,588 that the monohydric and dihydric esters of unsaturated fatty acids, when sulphurized, will yield products which may be added to hydrocarbon oils to obtain improved lubricants. 2

We have discovered that certain of the monohydric and dihydric esters, when prepared in a certain manner, are superior corrosion inhibitors and are therefore especially desirable for use with" the new type soft" metal bearings. Certain of these compounds falling within the generic class and prepared in accordance with our invention, have the furtheradvantage that they are oxidation and sludging inhibitors.

We do not know the theory of the new eifects produced. We believe, however, that the corrosion inhibiting and antioxidation effects of v these monohydric and dihydric esters, prepared in a certain manner, may be explained. Most metals tend to act as catalysts increasing the 40 rate of oxidation. For example, whena hydrocarbon oil is heated in contact with air in the presence of copper, a sludge comprising hydrocarbon oxidation products will form much more rapidly than if the oil is heated to the same temperature in a glass container out of contact with copper. This oxidation increasing effect of metals is true to various degrees for other metals, Soaps and oxides of such metals as cadmium and iron are catalysts in oxidation reactions for pe troleum derivatives and are used, for example,

in the preparation of fatty acids and other oxidatlon products from hydrocarbonsYThe sulpuhurized esters of our invention are strongly polar compounds and we believe they tend to form a protective layer over metallic parts serving to insulate the metal from the main body of oil, thus inhibiting the catalytic effect of the metal toward oxidation. We believe, further, that traces 05; such metallic salts as do form, such as iron. soaps, copper soaps, lead soaps and cadmium soaps, which result from the reaction of the oxidized hydrocarbons with the metals, are precipitated by the sulphur in our sulphuretted esters. The sulphides are insoluble in. hydrocarbon oil and are much poorer oxidation catalysts than the soaps and the metals themselves. By the formation of sulphides and their precipitation, the catalytic efiect is decreased and the oxidation is minimized.

-We have discovered that certain types of sulphurized esters are superior to others and that these could be most advantageously prepared in certain ways. This type consists of monoand dihyciric esters prepared from fatty oils in which the linolenic or similar two double-bonded fatty acid content ranges from 10 to 60% and in which the linolenic or similar three or more doubleboiided fatty acid is present in quantities less than 5 per cent.

The instant application relates more particularly to the monohydric alcohol esters and particularly the methyl esters of those fatty acids, the glycerides of which are normally present in corn oil. Those particular fatty acids, when sul phurized, produce a very superior corrosion inhibitor having marked antioxidation and antisludging properties as well as the property of increasing oiliness.

The superiority of these monohydric or di hydric esters of corn oil fatty acids over other similar esters of other fatty acids is due in part to the fact that, when prepared to contain more than one atom of sulphur to the molecule (12 to 18 per cent sulphur), they givea solution in refined mineral oil which does not become cloudy.

The other high sulphur content esters, when blended with mineral oil, develop a cloud on standing for a week or more. While this cloud has no harmful effect upon the oil, it detracts from its appearance and increases sales resistance.

The inhibiting effect on corrosion of an oil comprising a hydrocarbon oil containing a sul-' .phurized monohydric or dihydric ester of corn oil fatty acids was made with the Underwood apparatus which was developed by the General Motors Research department. It consists of a chamber in which the soft metal bearing inserts are positioned and subjected to jets of oil under a pressure. of 10 pounds per square inch. The oil is held at 350 F. and the test is run for a five hourv period. 3 quarts of oil are charged to the apparatus and circulated. The oil becomes oxidized during the test by contact with the air which is free to circulate in and about the ap-.

paratus. In order to speed up the corrosive eife'ct of the oil, a soluble lead soap (usually lead naphthenate) is added. In testing our inhibitor, we used a highly refined hydrocarbon (J as the base and added lead naphthenate to the extent of .05 of one per cent (calculated as lead oxide). The mineral oil containing the lead naphthenate occasioned a loss of 450 mg. on a copper lead alloy bearing insert and 1810 grams on a cadmium alloy bearing insert. The mineral oil containing the .05 of one per cent of lead naphthenate was blended with .1 of one per cent of sulphuretted methyl ester ofcorn oil acids containing 18 per cent of sulphur. Testing this .insert was 10 mg.

blend, the loss on a copper lead insert was only 10 mg. and the loss upon a cadmium alloy or maize oil. These esters may be prepared in ly by stirring at any temperature below 390 F. and preferably be ween 360 and 370 The sulphur compound should be refined by means of any suitable method which will re-' move free and unstably bound sulphur and also improve its color. Among methods that are satisfactory is contacting the sulphur compound with activated clays or carbons at temperatures of approximately 300 F.

A sulphurized ester containing about 18 per cent of sulphur may be thus prepared, which will not darken copper when blended with oil and has a powerful inhibiting eifect upon corrosion as hereinbefore pointed out.

As little as 5 to 10 per cent of suphur may be incorporated in the ester in preparing our inhibitor. Less than 10 per cent however is not recommended as the effectiveness of the inhibitor increases with increase in sulphur con tent. More than 20 per cent of sulphur is not advisable since the sulphurized esters 'will .be too dark and will tend to be insoluble in hydrocarbon oils- The quantity of-inhibitor to be used when blending with'a hydrocarbon oil depends largely upon the characteristics of the crude oil from which the lubricant is made and the degree of refining as well as conditions of use. From .01 of one per cent to 5 per cent by weight of sulphurized ester with respect to the hydrocarbon oil is usually sufiicient to accomplish the desired results. v

While we have described our sulphurized ester for addition to a hydrocarbon oil, it is to be understood that it may be employed with a hydrocarbon oil, thickened with a soap, that is, a grease or greaselike lubricant as well as lubricating oils, properly so-called.

It. will be understood that certain features and subcombinations are of utility and may be employed 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 details within the scope of our claims withinvention, what ganic acids. the glycerldes of which are normany present in corn oil.

4. A lubricant including in combination a major proportion of hydrocarbon oil and a. minor proportion of a sulphurized monohydrlc or dihydrlc ester of fatty acids, the glycerides of which are normally present in corn oil, said ester containing from 10 to 20 per cent of sulphur.

- BER-T H. LINCOLN.

WALDO L. BTEINER-