US2179061A - Manufacture of lubricating compositions - Google Patents

Description

Patented Nov. r, 1939 TES PATENT OFFICE MANUFACTURE OF LUBRICATING COMPO- SITIONS No Drawing. Application January 22, 1936, Serial No. 60,357

12 Claims.

This invention relates to the manufacture of lubricants and it comprises improved methods of making compounded lubricants useful in lubricating metal surfaces either under ordinary or 5 high pressure, particularly the latter, wherein mono-esters of fatty acids are first sulfurized to form substantially neutral organic sulfur compounds and then the sulfurized fatty esters so obtained are compounded with suitable lubril cating compositions such as mineral lubricating oils, etc., in suflicient amount to give a compounded lubricant having the desired properties, and it also comprises the improved lubricants so obtained, the compounded lubricant be- 15 ing stable in storage and in use and being substantially non-corrosive to metal; all as more fully hereinafter set forth and as claimed.

Mixtures of mineral oil with sulfurized oils are well known, such mixtures having been used as cutting oils, etc. sulfurized fatty oils, obtained by adding sulfur to a fatty oil such as lard oil, etc., and heating the mixture for several hours, have been frequently used in making such cutting oils. Likewise it is well known that the addition of sulfurized oil to mineral oils, im-

25 parts extreme pressure characteristics to them. There being a demand for lubricants which in the form of thin films are capable of. withstanding high pressures, such as occur in the gear and transmission combination of modern automobiles and other machines, it has been proposed to use mixtures of mineral oil and sulfurized fatty oil for lubricating such machines. However, it has been found that the usual mixtures are not sufficiently stable in storage or in use or both and that they are more corrosive than is permissible.

The ordinary fatty oils or esters heretofore employed for said purposes are glycerides; they being triesters of glycerine in which the glycerine is esterified with three mols of fatty acid.

40 I have found that it is somewhat difficult to control the sulfurization of such tri-esters and that many of the sulfurized products obtained from them are not suitable for blending with lubrieating compositions for several reasons. For one thing, they frequently lack suiiicient solubility for blending with many of the usual lubricating bases. Again, when sufficiently soluble to permit blending with mineral oil under some conditions, they are insufliciently miscible over a range 50 of conditions to permit the production of. good stable compounded lubricants. Further, many of the miscible'mixtures of sulfurized tri-esters of fatty acids and mineral oils are often quite 55 corrosive to various metals, particularly certain alloys. In many cases this corrosiveness, while not apparent in the freshly prepared compounded lubricant, develops during storage or in use.

I have found that the unsaturated mono-esters of fatty acids can be readily sulfurized to obtain 5 substantially neutral organic sulfur compounds. Those sulfurized mono-esters have many properties which render them advantageous as an ingredient in compounded lubricants. I have further found that stable, non-corrosive lubricants having the requisite commercial properties can be obtained by compounding minor amounts of the said sulfurized mono-esters of fatty acids, with the usual lubricating compositions such as the usual mineral oils, etc., with or without additional ingredients. In this way, I obtain superior compounded lubricants. By varying the amount of the sulfurized mono-ester and the particular mineral oil used, a wide range of commercial lubricants can be obtained.

Generally, the lubricating compositions of the present inventions comprise a major proportion of lubricating oil and a minor amount of a sulfurized mono-ester of a fatty acid, say from 0.1 to 30.0 per cent of the sulfurized ester. If desired, other ingredients may be present, such as the usual bodying agents, solid lubricants, etc., necessary in greases and other special types of compositions for particular purposes. My new lubricating compositions containing the said sulfurized mono-ester are particularly useful as extreme pressure lubricants. That is, they are satisfactory for lubricating metal parts and the like which are subjected to relatively high pressures and bearing speeds. Also they are advantageous in lubricating various metals and alloys which are attacked by many of the ordinary lubricating oils such as those obtained from highly refined stocks of the parafilnic type or thelike. That is, the sulfurized mono-esters of fatty acids have an inhibiting action when compounded with such oils. My new compounded lubricants also have other advantageous properties arising from the inherent characteristics of the sulfurized mono-esters here employed.

In making the new compounded lubricants the said mono-esters may be sulfurized in any suitable manner and the sulfurized mono-ester incorporated with the selected lubricating base in any appropriate manner. As the said monoesters are readily sulfurized and the sulfurized mono-ester obtained are readily soluble and miscible with mineral oils and like lubricants, various procedures may be employed in each of 10 paraflin waxes in that they contain an ester group. Such unsaturated mono-esters may be represented by the following general formula:

.wherein R. represents an aliphatic group, at least one of said aliphatic groups being unsaturated.

In practicing this invention, pure mono-esters or mixtures thereof may be employed. The esters or mixtures which are liquid at room temperature and which have a boiling point substantially above 370 F. are advantageous. To produce high grade sulfurized products, for the present purposes, I find it advantageous to use, as the starting material, ester materials having the following properties:

Specific gravity, 60/60 F (1878-0384 Viscosity: S. U. V., 100 F 95-110 Flash, 0. C., F., minimum 490 Pour, F., maximum +40 Color, N. P. A. not darker than 1.5 Neutralization number, maximum--- 0.5 Oleic acid eq., percent, maximum-" 0.25 Saponification number 125-135 Iodine number 30-90 Good grade sperm oils having such properties are readily available and are generally used in the commercial practice of this invention.

It is known that sperm oil is a mixture of monoesters of the general type given ante; the esters thereof being mono-esters of unsaturated fatty acids of the oleic series and of monohydric alcohols of the ethylene series. Thus in the general practice of the invention one or more of the monoesters present in sperm oil may be used. Likewise, other unsaturated mono-esters can be employed; for instance, the mono-esters of simple alcohols, such as methyl, ethyl, etc., may be used when the aliphatic chain of the unsaturated acid is sufliciently long to give the ester the desired physical properties. That is, with esters of the higher fatty acids, the aliphatic group of the alcohol may be a relatively short chain; the total length of the whole ester chain being important in securing the results here obtained. However, with the higher alcohols, the esters are more balanced in relation to the ester group and this is advantageous for many purposes. Likewise, it is advantageous to employ esters in which there is unsaturation in the aliphatic group of the alcohol component. With the esters of such alcohols, the aliphatic group of the acid component may be saturated or may have a shorter chain or both.

The various major types of mono-esters here used may be represented by the following formulae:

wherein both R2 and R3 are olefinic aliphatic chains; the R2 and R3 being advantageously chains having the formula CnH2n 1. When n is at least 3 and each chain has a terminal CH3 group, good sulfurized products are readily obtained; the sulfurized esters being quite miscible with mineral oils.

wherein R3 is an olefinic aliphatic chain and R4 is a saturated aliphatic group. The statements made ante, as to the advantageous types of olefinic aliphatic groups, are also applicable to this class of mono-ester.

wherein R5 is a saturated aliphatic group and R2 is an olefinic aliphatic chain. Advantageously, the R2 may be a chain containing a terminal CH3 group and having the formula -CnH2n-1, with n being at least 3.

The unsaturated mono-esters of Classes 11 and III, ante, may be represented by the following generic formula wherein R and R1 represent straight chain aliphatic groups, one of said groups being saturated and the other being unsaturated. In my companion application Ser. No. 108,305, which is a continuation-in-part of both the present application and my Ser. No. 715,551, I describe and claim the manufacture of substantially neutral organic sulfides from this class of unsaturated mono-esters by reacting sulfur with such esters to form addition products; both the method of sulfurizing and the products so obtained being there claimed. The sulfurized mono-esters there claimed are readily soluble in mineral oils and are advantageous in the practice of the present invention as they improve the lubricating properties of such oils when dissolved therein.

In another copending application Ser. No. 108,306, which is also a continuation-in-part of my Ser. No. 715,551 and of the present appication, as well as a continuation-in-part of my companion application Ser. No. 60,355, I describe and claim the sulfurized esters obtained from the mono-esters of Class I ante, in addition to specifically claiming sulfurized sperm oils and methods of sulfurizing the same.

In other words, I have found that in lieu of natural mixtures of esters, such as sperm oil, etc., the esters of Class I are likewise advantageous. They are representative of the characteristic esters of sperm oil. That is, the ester is unsaturated (contains double bonds) in both the acid and alcohol components thereof. Generally, the esters of oleic acid and other monocarboxylic acids of the oleic series with unsaturated monohydric wax alcohols may be employed. For instance, the mono-esters having the following formula:

II II (a) H H wherein a: is from 1 to 7, have various properties both in the original and sulfurized state. that are desirable in these methods. The oleates are satisfactory and are ordinarily employed. The neutral stable sulfide of the oleate of oleic alcohol may be represented by the following formula:

s HQC-CHn-(CH:)5CHa-C-CCHr(CH1)r-CHrC-H s H The oleate of oleic acid is typical of the balanced esters wherein the acid is esterified with the corresponding alcohol; such esters having the formula wherein R. is the like olefinic aliphatic groups. However, the alcohol component of the ester does not necessarily have to correspond with the acid component thereof. The oleates of any of the olefinic alcohols present in sperm oil may be used.

The following specific esters are typical and illustrative of the general Class I:

Allyl oleate Decylene oleate Dodecylene oleate Pentadecylene oleate The esters of Class II are similar to those of Class I except that the alcohol component is a saturated aliphatic compound. Here again, the oleates are satisfactory and are ordinarily used.

' Generally, for most purposes, satisfactory results are obtained with the esters having the following formula:

wherein m and a: are at least I; particularly those in which a: is 1 to '7 and m is l to 20.

However, any of the unsaturated mono-esters of the monohydric alcohols having the formula HO-CHz-(CH2)nCH3 wherein n is 4 to 16 are advantageous for many purposes. The oleate of dodecanol is illustrative of such esters.

Again, the methyl, ethyl, propyl or butyl esters of olefinic monocarboxylic acids such as oleic acid may be used.

The following specific esters are typical and illustrative of the general Class II:

Methyl oleate Iso-propyl oleate Hexyl oleate Lauryl oleate Cetyl oleate On the other hand, the mono-esters of Class III are similar to those of Class I, except that they contain a saturated fatty acid component. The esters of the olefinic monohydric alcohols of s'perm'oil, with appropriate fatty acids may be employed. In using this class of mono-esters, those containing the same alcohol component as shown in Class I, are employed. The monoesters of this class which have the following formula:

wherein m and a: are at least 1, are advantageous. They are high-molecular weight mono-esters of saturated fatty acids with alcohols of. the ethylene series. The fatty acid component thereof may be any of those having an aliphatic chain within the range indicated which will produce the desired physical properties and boiling ranges.

The following specific esters are typical and illustrative of Class III:

Allyl palmitate Decylene laurate Dodecylene caprylate Oleyl butyrate Any of the above mono-esters may be readily sulfurized to obtain neutral organic sulfur compounds useful for the present purposes. Generally, esters of Classes II and III require less sulfur to form the neutral compounds than do the esters of Class I; they only having unsaturation (double bonds) on one side of the ester group.

In the broad practice of this invention any mono-ester, within the scope of the following formulae, may be used to advantage in making sulfurized esters capable of improving one or more of the lubricating qualities of mineral oils and like lubricants:

wherein R is an aliphatic group and a: is at least 1.

H H H wherein R is an aliphatic group and a: is at least 1.

The above Formula d is sub-generic to the major Classes I and II, whereas Formula 6 is subgeneric to Classes I and III.

In preparing the sulfurized esters, the said unsaturated fatty mono-esters may be sulfurized by any method which yields substantially neutral organic sulfur compounds recoverable as such, in a form that is sufficiently free of corrosive and insoluble bodies. Advantageously the mono-ester may be reacted with suitable amounts of sulfur at a temperature between 300 and 380 F.; the reaction being continued until the sulfur is combined in the form of neutral organic sulfur compounds. Usually from to 20 parts of sulfur to 100 parts of ester are employed. Generally I employ substantially the amount of sulfur that is necessary to saturate the double bond of the ester used. The degree of the unsaturation of the ester can be readily determined by means of its iodine value or number.

In one method of controlling the sulfurization, the mono-ester is first preheated to about the lower reaction temperature (300 F.) and then the required amount of sulfur is gradually added to the preheated ester, the rate of addition being adjusted so that the temperature of the reaction mixture is gradually and quietly increased to just below the upper limit (380 F.) After all the sulfur has been added, the temperature tends to drop slightly and then the reaction mixture is maintained at about 340 F. until the reaction is complete. The course of the reaction may be easily followed by withdrawing test samples and determining the change in viscosity. After the proper viscosity has been obtained the end point can easily be determined by diluting the sulfurized oil with a standard amount of mineral oil and determining its corrosive action upon a cop- Cir per strip. When the copper strip remains unattacked or shows only a slight stain, the reaction is complete. Then the sulfurized ester is cooled to room temperature. It can be stored in metal drums and other suitable containers.

The copper strip test here employed was devised by me in 1917 for determining the relative corrosiveness of lubricating oils. The procedure is as follows:

A mechanically polished copper strip half inch by 3 inches is immersed in 25 cc. of lubricant contained in a test tube which is placed in a boiling water bath, and held at the temperature of boiling water for 3 hours. At the end of this time the strip is removed and adhering oil washed off with a light naphtha and examined for evidence of corrosion. A negative test is one in which the strip shows only a slight stain or discoloration. The positive test is one where the strip shows considerable discoloration or tendency to scale, indicating presence of corrosive constituents in the lubricant.

In preparing the diluted sample for a test, I ordinarily use a standard mineral oil having the following properties:

Gravity, A. P. I 27.1 Specific gravity, 60/60 F 0.8922 Viscosity, S. U. V.:

210 F 89 Viscosity index 92 Flash, 0. 0., F 470 Fire, 0. 0., F 545 Pour, F +5 Color, N. P. A dil 4.25 Carbon residue, percent 0.44 Neutralization number 0.01

The sample of sulfurized ester is diluted with the above mineral oil in the ratio of :90 to obtain the sample used in determining the corrosion by the copper strip method The copper strip is removed from the heated oil sample after 3 hours, and then wiped dry and inspected in the usual manner. Sometimes, a test mixture the same as the desired compounded lubricant is used in the above test.

With the above mentioned controlled methods of sulfurization there is but little loss of sulfur; the percentage of combined sulfur in the sulfurized ester is approximately that in the reaction mixture. During the sulfurization very little hydrogen sulfide is formed. With careful operation, finely divided sulfur may be gradually added to the preheated ester by sifting, etc., with little or no mechanical loss of sulfur.

The viscosity of the ester increases as the sulfur is added and upon combination of most of the sulfur the viscosity tends to remain substantially constant as the heating is continued. While the reaction temperature should be sufiiciently high to obtain the best combination of the sulfur, exceedingly high temperatures should be avoided to prevent undesirable side reactions.

In such methods, all the sulfur is usually added within about 2 hours and ordinarily from 16 to 24 hours further heating at a temperature between 300 and 380 F. is required to combine the added sulfur. The sulfurized esters so obtained have a combination of properties rendering them particularly useful as an ingredient in compounded lubricants. Similar sulfurized esters may also be obtained by other methods wherein sulfurization is appropriately controlled.

Gravity, A. P. I 12.6-15.6 Viscosity, S. U. V., 210 F 100300 Pour, F (not greater than) +45 Sulfur, percent 6.016.0 Neutralization number 1.0-6.0

However, as set forth post, sulfurized esters having somewhat different properties may be used in special cases to produce particular types of lubricating compositions.

The sulfurized fatty mono-esters here employed are really soluble in the ordinary grades of lubricating oils. They are fully miscible and compatible with the high gravity oils such as paraffinic base oils (Pennsylvania, etc), and solvent refined oils, etc., over a wide range of conditions such as temperature, proportions, etc. When they are compounded with such mineral oils, improved compounded lubricants are obtained which are remarkably stable, as well as having viscosities, viscosity indexes, specific gravities, pour points, etc., capable of meeting the technical specifications for high grade commercial lubricants. Their lubricating qualities over a wide range of utilization are excellent.

' The various sulfurized fatty mono-esters may be incorporated with mineral oil or any of the ordinary mineral oil lubricants to obtain improved compounded lubricants. Of course, varying amounts of sulfurized mono-ester may be employed as stated ante, according to the compounded lubricant desired and the mineral oil base used. Various types and grades of mineral oil and the lubricating bases obtained from them may be so improved.

In making compound lubricants, the desired amount of sulfurized fatty mono-ester is added to the selected mineral oil and the mixture heated and agitated until a uniform blend is obtained. By using temperatures between 70 and 200 F. for oils and often higher temperatures for greases, for this mixing, the sulfurized ester quickly blends with the oil or grease. Sometimes the oil or grease may be preheated to such temperatures before adding the sulfurized esters. Again, the sulfurized ester while hot, for instance, the hot product from the sulfurizing operation, may be run into unheated or preheated mineral oil, etc. However, the mixing may be effected at room temperature; it being sometimes advantageous to first dilute the sulfurized ester with a part of the mineral oil forming, so to speak, a master batch of the extreme pressure ingredient and the mineral oil. Such master batch can be prepared hot, and then mixed in the bulk of the mineral oil at a lower temperature; that is, the hot master batch may be cooled and the subsequent mixing of the final lubricant effected in the cold. In any event, thorough agitation is desirable to insure the production of uniform compounded lubricants. Suitable mechanical agitating devices may be used. Or a current of gas may be blown through the mixture to stir it. The gas in passing through the oil will remove any volatile component that may be dissolved therein. A current of air may be used for this purpose, but other inert gases,

such as carbon dioxide, nitrogen, etc., may be employed. If high temperatures are used during the mixing and blending, the gas employed should be inert under the given conditions. Generally, when the mixture is stirred and agitated mission units and the motors of automobiles may be produced. The lubricant may be either winter or summer grade. The two grades may be easily parts sulfur.

obtained by simply varying the mineral oil base employed; it being only necessary to select a standard grade of winter or summer mineral oil and add the amount of sulfurized ester required to impart the desired extreme pressure characteristics and improvement thereto. With most of the sulfurized esters here employed, usually they are blended with the mineral oil in ratios, by volume, between 10:90 and 14:86. The extreme pressure lubricants so produced are high grade, stable non-corrosive materials. They show a marked increase in the load carrying capacity over the oil base, as determined by either the Almen or Timken test for E. P. lubricants. Being stable they can also be used for ordinary lubrication wherein the usual pressures are encountered. V

The following examples are illustrative embodiments of the methods and products broadly set forth ante and are not limitive of the invention:

Example 1.-This example illustrates the sulfurization of an ester of Class I; a balanced ester being employed.

The oleate of oleic alcohol is sulfurized at temperatures between 32 5 and 360 F. with about 12 per cent of sulfur by weight on the said oleate, by reacting 500 parts of said oleate with 60 parts of sulfur. There is obtained a sulfurized monoester containing 10.7 per cent of sulfur and having a viscosity S. U. V. at 210 F. of approximately 200-350.

The oleate of dodecylene alcohol may be likewise sulfurized. This oleate requires 14.38 per cent sulfur to convert it into a substantially neutral sulfide containing 12.5 per cent combined sulfur. In practicea good product is obtained by sulfurizing 100 parts of this oleate with 14 Again the decylene acid ester of decylene alcohol may be employed. It requires 17.0 per cent of sulfur on the ester to convert it into a substantially neutral sulfide containing 14.9 per cent of combined sulfur.

Example 2.-This example illustrates the sulfurization of an ester of Class II; a simple alkyl ester of an unsaturated fatty acid being employed.

Ethyl oleate is sulfurized at temperatures between 300 and 360 F. with about 12 per cent of sulfur by weight on the said ethyl ester. There is obtained a sulfurized mono-ester having the following properties:

Gravity, A. P. I 15.4 Specific gravity, 60/60- F 0.9632 Viscosity, S. U. V.:

210 F 44 Pour, F +20 Sulfur (B), per cent 10.08 Neutralization number 5.5

In lieu of the ethyl oleate, the propyl oleate may be employed. This oleate requires about 11 per cent of sulfur to form the substantially neutral sulfide.

Likewise, the ester of higher saturated alcohols may be used. The oleate of dodecyl alcohol requires 8.8 per cent sulfur to form a neutral sulfide is Lorol, a trade product obtained by bydrogenating the fatty acids of cocoanut oil. The sulfurized mono-ester obtained from this oleate has the following properties:

Gravity, A. P. I 15.0 Specific gravity, 60/60 F 0.9659 Viscosity, S. U. V.,210F 94 Pour, F +25 4 Sulfur (B), per cent 6.5 Neutralization -1 2.0

Example 3.--This example illustrates the s'ulfurization of an ester of Class III; an unsaturated alcohol ester of a saturated fatty acid being employed.

v The decylene palmitate is sulfurized at tem peratures between 300 and 360 F. with about 10 per cent of sulfur by weight on said ester by reacting parts of. the said ester with 10 parts of sulfur in the manner described ante. There is obtained a sulfurized mono-ester having the following properties:

Gravity, A. P. I 14.8 Specific gravity, 60/60 F 0.9672 Viscosity, S. U. V., 210 F Pour, "F +25 Sulfur (B), per cent 8.3 Neutralization number 1.9

Any of the sulfurized mono-esters obtained in Examples 1, 2 and 3 may be employed in maldng excellent E. P. lubricants, by incorporating them in various grades and types of mineral lubricating oils. Generally sufficient sulfurized mono-ester is added to the mineral oil to form a composite E. P. lubricant containing at least 1.40 per cent of combined sulfur; substantially all the sulfur being combined in the form of non-corrosive organic sulfur compounds. In this way I can obtain commercial E. P. lubricants of excellent 1 quality such as those meeting the following specificationsz Winter Bummer General grade grade Gravity, A. P. I 23.0-26.5 24.6-26 5... 23.0-25.0. Viscosity, S. U. V.,210 F.. 60-210 60-100.--" 150-210. Flash, 0. C. F., (minimum 460 550. Pour,F +5 to +15. +5 +15. Sulfur, percent (minimum). 1.40 1.40. Corrosion test, 212 F., 3

hours Slight tarnish Same Same.

0!! y. Centrifuge test, 2 hours room temperature, percentseparated(maximum) 0.05 0.05 0.05. Load capacity:

Almen rating, 600 R. P. M. lever load,

Ounds, (minimum).. 16 1e 10. T mken rating, 800 R. P. M.l00-l35 F., 10 min., lever load, pounds, (minimum).. 40 40 40 In producing such E. P. lubricants I generally find it is advantageous to use sulfurized monoesters having the following properties:

Viscosity S. U. V., 210 F 200300 Sulfur, per cent 10.0-12.0

and compound them with a suitable mineral oil base; 5-20 volumes of such sulfurized monoesters to 95-80 volume of mineral oil base being an advantageous ratio.

Example 4.This example illustrates the manufacture of extreme pressure lubricants. A mineral oil (winter grade) was employed which had i the following properties:

Gravity, A. P. I 27.1

Specific gravity', sir/60 F 0.8922

To 88 gallons of the above mineral oil there was added 12 gallons of the sulfurized ethyl oleate obtained in Example 2. The mixture was warmed to 160 F. and a current of air blown through it until a uniform blend was obtained. This required about one hour. "The product was filtered but no significant amount of foreign mat- Carbon residue, per cent ter was found to be present. The compound lubricant so obtained is an excellent winter grade E. P. lubricant well within the specifications given ante.

To obtain a summer grade E. P. lubricant by the above procedure, in lieu of the winter grade oil, there is substituted a summer grade lubricating oil having the following properties:

Gravity, A. P. I 25.1 Specific gravity, 60/60 F 0.9036 Viscosity, S. U. V.:

100 F 4329 130 F 1513 210 PL 206 Viscosity index 94 Flash, 0. C., "F 580 Fire, 0. C., F; Pour, F Color, N. P. A dil +5 7.0 1.30 Neutralization number 0.01

Again, an excellent E. P. lubricant is obtained having properties meeting the specifications given ante.

' In the above examples the ratios and other details may be varied as indicated in the general description ante, to obtain various specific products. Two or more mineral oils may be mixed and blended to obtain suitable or special bases for making the E. P. lubricantif necessary or desired.

By the various methods shown I obtain a series of compound lubricants having properties meeting the specifications for superior E. P. lubricants, set forth ante.

The examples of mineral oil bases used are for purposes of illustration. Naphthenic oils, oils of mixed bases and, in fact, any commercial oil may be used.

The E. P. lubricating oils of the present invention may be further compounded with other ingredients, such as soaps, graphite, finely divided metals, bodied vegetable, animal and fish oils, etc., to obtain special products such as greases and the like.

A decided advantage of the sulfurized fatty mono-esters in a lubricant is that under normal lubricating conditions it is better than the usual oil and their presence in a lubricating composition makes it particularly useful when extreme pressure lubricants are needed.

That is, my compounded oils utilizing the sulfurized fatty mono-esters as described are particularly useful in a number of relations, as for instance, as marine engine oils,,motor oils and in making locomotive driving journal compounds where special greases are needed.

This application is in part a continuation of my prior copending application Serial No. 715,- 551, filed March 14, 1934,now United States Patent'No. 2,065,247, patented December 22, 1936, and it is also related to my copending application Serial No. 60,356, filed January 22, 1936, now United States Patent No. 2,065,248, patented December 22, 1936. a

In steam cylinder lubricants where relatively high temperatures and rubbing speeds prevail, my compound has decided advantages over the usual rapeseed bodied oil compounds. Such compounds containing rapeseed oil and naphthenic or coastal ufacturers to use special bearing alloys, such as cadmium-silver alloys, cadrniummickel alloys, cQpper-lead alloys, and the like, there is a demand for certain grades of lubricants which will not have corrosive action on them. I have found that a small percentage (0.1 to 1.0 per cent) of sulfurized fatty mono-esters in motor oils having high viscosity index, such as Pennsylvania 'base oils and solvent refined oils, will eliminate their corrosive action on the special type of alloy bearings to which reference has been made.

In greases used for locomotive driving journals and the like the melting point must necessarily be rather high, with the result that the wetting power of the lubricating constituent is "somewhat limited. The addition of sulfurized fatty mono-esters to such compound imparts a decided oiliness or wetting power, even when as low as 1 to 2 per cent is used in greases of this type. In types of greases such as those used in automobile wheel bearings, high speed ball bearings and the like, where the lubricants fume-- tion under relatively mild bearing loads but high bearing speeds, from 2 to per cent of sulfurized fatty mono-ester can be used to decided advantage.

A typical good marine engine oil comprising sulfurized fatty mono-esters is shown in the following exam'ple: A

Example 5.In preparing a marine engine oil I employ the following oil:

and to '70 parts of such oil, I add 5 parts of sulurized methyl oleate and 25 parts of blown rapeseed oil.

Example 6.-In preparing a marine engineoil I employ the following coastal lubricating oil distillate of the following properties:

Gravity, A. P. I 20.7 Vis'cosity, S. U. V.:

210 F 89 Flash, 0. 0., F 470 Fire, 0. C., "F 545 Pour, F -5 Color, N. P. A 4.5 Carbon residue, per cent 0.3 Neutralization number 0.02

and to 70 parts of such oil I add 3 part of sulfurized iso-propyl oleate and 27 parts blown rapeseed oil.

Example 7.The following is illustrative of a typical motor oil:

and to 100 parts of this oil, I add.0.75 part by weight of sulfurized lauryl oleate.

Example "8.-The following is an illustration of a locomotive driving journal compound:

Make-up: per cent by weight:

to 150 dark filtered cylinder stock 42.9 Sodium-stearic acid soap 3.0 Sodium-tallow oil soap 49.5 sulfurized lauryl oleate 4.6 Oil of cassia 0.003

45 Inspection:

Penetration, A. S. T. M., 77 F., un-

worked 66 Example 9.-The following is a typically good steam cylinder lubricant:

Make-up: per cent by volume: Per cent 120 vis. 210 F. Mid-Continent Bright Stock 150 vis. 210 F. Mid-Continent Bright Stock 10 sulfurized ethyl oleate 5 Acidless tallow 5 Inspection:

Gravity, A. P. I 26.1 Viscosity, S. U. V., 210 F 115 Flash, 0. 0., F 510 Pour, "F +15 Example 10.The following is a typically good grease for automobile wheel bearings, high speed ball bearings and the like:

Make-up: per cent by weight:

300 red parafiin oil 79.5 sulfurized methyl oleate 4.8 Sodium tallow soap 13.9 Glycerine 1.4 Water 0.4 Oil of cassia 0.002

Inspection:

Melting point, F., Hawxhurst 158 Penetration, A. S. T. M., 77 F., un-

worked 317 The addition of sulfurized fatty mono-esters to lubricating compositions has several advantages. Its presence in the lubricating com positions renders the lubricant useful as an extreme pressure lubricant wherever desired. Further, the sulfurized fatty mono-esters also function as corrosion inhibitors and render the composition generally more stable. In compositions containing other ingredients in addition to the mineral oil, the sulfurized fatty mono-esters serve as blending agents increasing the uniformity of the mixture. Likewise it is useful in increasing the oiliness of the compounded lubricants. In other words, the sulfurized fatty mono-esters in the composition set forth ante has many and diverse effects and functions, all of which are advantageous.

In my copending application Serial No. 60,355 which is related to the present application, I have described and claimed the manufacture of improved lubricants wherein sulfurized sperm oil, etc., are added in minor amount to lubricating compositions in which the lubricating base is or contains a major amount of mineral oil. The specific embodiments there disclosed are a part of the present broad invention and may be used in the practice thereof.

While in the foregoing examples I have described direct sulfurization of the mono-esters, I at times find it advantageous to sulfurize them in the presence of a diluent oil, as for instance a petroleum hydrocarbon oil, which may well be the same as the oil used for the base for manufacturing the compound lubricant. That is, some of the mineral oil may be mixed with the monoester prior to the addition of the sulfur. The use of relatively high boiling diluents with the lower boiling mono-esters is advantageous, as in this way molten sulfur can be readily brought into contact with the ester. Also by employing diluent oil, the reaction mixture may be maintained in a freely mobile state, even with the esters of the greatest molar weight.

When a mixture of sulfurized esters is to be employed, I sometimes blend together two or more sulfurized products, instead of sulfurizing a mixture of esters. In this way a more direct control and adjustment of the properties of the sulfurized material, for addition to special lubricants, may be obtained.

What I claim is:

1. As an improved compound lubricant, a uniform blend of a mineral oil lubricating base and a minor amount of a sulfurized fatty mono-ester derived from an ester having the following formula wherein R and R1 represent aliphatic groups, at least one of said groups being unsaturated prior to sulfurization, said lubricant being stable both in storage and in use and being non-corrosive to metals.

2. The improved compound lubricant of claim 1, wherein said lubricant is an extreme pressure lubricant, the lubricating oil base is a solvent refined mineral oil having the following properties:

Gravity, A. P. I 23.026.5

Viscosity, S. U. V., 210 F 60-210 Flash, 0. C., F., minimum 460 Pour, F., maximum +15 Sulfur, per cent, minimum Corrosion test, 212 F., 3 hours Slight tarnish only Centrifuge test, 2 hours room temperature, per cent separated, maximum 0.05 Load capacity:

Almen rating- 600 R. P. M., lever load, 1b.,

minimum 16 Timken rating- 800 R. P. M., 100-135 F., 10

min., lever load, 1b., minimum 40 and the compound lubricant contains between wherein R2 and R3 are olefinic aliphatic groups.

5. The improved compound lubricant of claim 1,

wherein said sulfurized mono-ester is derived from an ester having the following formula wherein R is an alkyl group and a: is at least 1.

6. The improved compound lubricant of claim 1, wherein said ester is sulfurized ethyl oleate.

7. As a composition of matter, useful as a lubricant, a stable non-corrosive uniform composition comprising a mineral oil and a substantially neutral sulfurized fatty mono-ester derived from an ester having the following formula wherein R3 is an olefinic aliphatic group and R4 is a saturated aliphatic group.

8. The composition of claim 7 wherein said sulfurized mono-ester is one having the following formula wherein a: and m are at least 1, said composition being non-corrosive to metals.

9. The composition of claim '7 wherein said sulfurized mono-ester is an ester of a monohydric alcohol having the following formula wherein m is from 0 to 20.

10. As a composition of matter, useful as a lubricant, a stable non-corrosive uniform composition comprising a mineral oil and a substantially neutral sulfurized fatty mono-ester derived from an ester having the following formula R5 CO-R1 wherein R5 is a saturated aliphatic group and R2 is an olefinic aliphatic group.

11. The composition of claim 10 wherein said sulfurized mono-ester is one having the following formula HHC(CH2)--C=O i i I Had-C112-(cimroIh-owc-c112 om),-cnz-o-H wherein cc and m are at least 1.

12. The compound lubricant of claim 1, wherein said sulfurized fatty mono-ester is one derived from an ester having the following formula wherein R is an alkyl group and :c is at least 1.

HERSCHEL G. SMITH.