US2433853A - Sulfurized oils - Google Patents

Description

Patented Jan. 6, 1948 UNITED STATES PATENT DFFiCE SULFURIZED OILS No Drawing. Application November 23, 1944, Serial N0. 564,898

Claims. 1

This invention relates, as indicated, to lubrieating compositions and more particularly to compositions for use in connection with the lubrication of the working parts of internal combustion engines, motor vehicles,- etc. And it is among the objects of the invention to provide compositions obviating the disadvantages of the usual petroleum oils.

It has long been known that sulphur compounds when added to lubricating oils impart certain properties to the mixtures which are of greater value when these mixtures are used as lubricants for very heavy duty such as is encountered in the lubrication of automotive gears of the hypoid and spiral bevel types and other power transmission gears and for the lubrication of cutting tools such as are used in cutting and threading steel pipe. The exact manner in which these compounds, with respect to the cutting lubricants, act to produce these results is not known with any degree of certainty. It is much more than a matter of increased film strength which such compounds impart to lubricating oils, since, for each sulphur compound that may be added to a lubricating oil to increase its film strength, there is an optimum percentage above which there is no tendency to obtain further increase with greater percentages of the addition agent. On the other hand, there seems to be no limit to the improvement of a cutting oil that can be obtained by increasing its sulphur content, at least as far as the smoothness of the metal cut obtained with it is concerned.

Not all sulphur compounds have this beneficial effect on lubricants to the same degree for the same amount of sulphur as will be brought out in the examples given herein below; and to most of those now in use there are certain definite objections'. The most common sulphur compounds used for blending with lubricating oils are the sulfuretted glycerides of the unsaturated fatty acids and these usually contain about 12% sulphur. Sulfuretted lard oil is a typical example. These compounds are not entirely satisfactory for blending purposes for several reasons. The sulfuretted glycerides are very viscous, hard to handle, raise the pour point of the oil with which they are blended, have a very strong odor of hydrogen sulphide, and are irritating to the skin of the operators working with them, are not as stable as desired when in use and do not give a good cut when used in a cutting lubricant, do not give a very high film strength when used in an extreme using a large percentage of these sulphur base oils, cutting lubricants are obtained which are rather inefficient such as for example the cutting qualities concerned are objectionable on account of odor, are irritating to the skin of the operators and in case Of slight cuts on the hand cause sores difiicult to heal, are very viscous when cold, are not stable to high temperatures when in use, and break down and release Has. An extreme pressure lubricant for gears which is made from the conventional sulfuretted glycerides such as lard oil has many defects. In the first place, this type of sulphur base blend is not as stable as is desired to the copper strip corrosion test which some automobile manufacturers now require for sulphur base lubricants. Secondly, the film strength is not very high; and last, the pour point of the lubricants is raised 5 to 25 F., depending upon the type of petroleum base oil used.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

Broadly stated this invention is concerned with the blending in a hydrocarbon oil of a minor proportion of a halogenated sulphurized (or sulfuretted) monohydric or dihydric alcohol ester of an organic acid, and more particularly with the phenolic esters of organic acids for the preparation of superior cutting oils, gear lubricants. crankcase lubricants, and the like.

The advantages of utilizing a compound containing both halogen and sulphur in a mono or dihydric alcohol ester of an organic acid are many. First, we combine the desirable properties of several addition agents commonly used in complicated proportions into one additive. Secondly, the diiiiculties encountered with conventional sulphur additives, i. e., odor, toxicity, increased pour point, stability, solubility, and etc., are entirely.

group much more stable to heat than the sulfuretted glycerides and consequently do not break down and release H23 in service as readily. When the glyceride breaks down, glycerine is released which forms gum and is generally objectionable.

When used in a cutting oil these halogenated sulphurized monohydric or dihydric alcohol esters of organic acids do not irritate the sinner the operators. They are cheaper because about twice as much sulphur may be added to this type of compound as can be added to the glycerides, and thus they give a more concentrated base.

Another important advantage of these synthetic esters, is that they are more soluble in petroleum lubricants than their. corresponding sulfuretted glycerides. The latter have a marked bottom of the container in which a blend of this type in a petroleum lubricant has stood for some time. The reason for this phenomenon is that glycerides tend to polymerize on sulfuretting and form oil-soluble polymers whereas their corresponding synthetic halogenated monhydric esters show little or'no tendency to polymerize on sulfuretting or sulphurizing. The pour point of blends made with a petroleum lubricant is higher, by to 25 F. (depending upon the type of tendency to showing sludge-like deposits on the lubricant) when sulfuretted glyceride is used than;

when the corresponding sulfuretted or sulphur ized halogenated synthetic monohydric alcohol ester is used. The latter compounds do not effect the emulsion characteristics and decrease the 4 temperatures and longer times of sulphurizing are employed as described below.

Some examples of the esters we may sulphurize are given below, and it is to be understood that any of the phenolic components mentioned may be combined with any of the acid radicals mentioned to obtain further examples of esters we may sulphurize. It is also to be understood that the following esters when sulphurized and blended with "mineral oil are to be considered as examples of our invention.

It is further to be understood that the time of introduction of the halogen into the molecule is of little importance. Halogen may be present before esterification in either the acid or alcohol reactant. It may be introduced following the process of esteriflcation, or the products'of our application Serial No. 312,408, now Patent No. 2,357,211, dated August 29, 1944, may be halogenated in any manner conventional or otherwise.

Throughout the. foregoing description of our invention, reference has been had uniformly to the halogens" generically. It is to be understood that the preferred halogen is chlorine, and next I in order of importance are fluorine, bromine, and iodine. The chlorinated species are generally preferable on account of their lower cost and ease of preparation. The fluorine species are of advantage, however, in that they are generally more stable than other halogens, and accordingly those compounds which have a tendency toberelatively sludge forming tendencies of the bas oil with which they are blended. 0n the other hand, the sulfuretted glycerides cause emulsion trouble and increased sludge formation.

Th viscosity of the sulfuretted glyceride blends is very much higher for the same amount of added sulphur at the same temperatures of 0 to 50 F. than similar blends where the halogenated sulfuretted or sulphurized synthetic monohydric aldifiicult to obtain a good flow of the cutting oil from the sump of the machines on cold mornunstable will preferably be combined with fluorine rather than any other 'of the halogens.

Chlorophenol esters of corn oil acids Iod oresorcinol esters of soy bean oil acids Guaiacol esters of chlorinated wool fat acids Esters of B-hydroxyquinoline with brominated beeswax acids 1 Chlorocatechol esters of wool fat acids Chlorothymol esters of beeswax acids Phloroglucinol esters of chlorinated corn oil acids o-Cresol esters of chlorinated beeswax acids Iodophenol esters of sperm oil acids ings in a shop that is not too well heated. Under these conditions, the machines do poor work, and the cutting tools are dulled. The disadvantages of a high pour test and a high viscosity at cold weather temperatures in the case of gear lubricants are responsible for excess loss of power in' overcoming the internal friction of the lubricant as well as difficulty in shifting of gears in the case of automobile transmissions.

We have found more particularly that certainl synthetic esters of mono and dihydric phenols with organic acids are especially suited to su1- phurization and use when blended in mineral oils for lubricating purposes, and in more particular refinements of our invention we prefer to use the halogenated species of the above described compounds. The mono and dihydric phenols which we may use may be monoor bior polycyclic and may contain various substituents and/or side chains in addition to the one or two hydroxyl groups.

cluding the acids (free or combined) occurring in The organic acids which we may use to esterify such phenols are of various types, in-

natural fats, waxes and saponifiable oils, as well as synthetic acids.

prefer the unsaturated type because their esters are easier to sulphurize than the saturated type. The latter may be satisfactorily used if higher Of these acids, however, we

Resorcinol esters of chlorinated acids of naturally occurringwaxes such .as camauba, candelilla, gondang, japan, montan, and bayberry waxes Chlorophenolic esters of the acids of naturally occurring waxes such as carnauba, candelilla, gondang, japan, montan, and bayberry waxes Chloroquinol esters of. brominated corn oil acids B, Esters of unsaturated organicacz'ds Xylenyl iodoethenate Chloroxylenyl alpha-chioronaphthyloleate .Chlorothymyl heptenate Thymyl chlorododecenate 'I'hymyl alpha-dichlorobenzyloleate Bromoguaiacol dilinoleate' Guaiacol alpha-chlorolaurylchlorocinnamate Dichloro-orcinyl hexenate a-Naphthalenyl alpha-chloromethylbenzylchlorobutenate Chloro-a-naphthalenyl alpha-chlorocresyllinoleate Bromoanthrenyl alpha hydrogallylbromocinnamate Anthrenyl dichloro-octenate Chloroquinyl di-alpha-thymylpentenate Quinyl chlorolinoleate Dichloro diphenyl butenate Diphenyl alpha chloroethylbenzylchlorolinoleate 4 Chlorolaurylphenyl heptenate Laurylphenyl alpha-chloromethylbenzyloleate Chlorobutylphenyl didodecenate Chlorodecylchlorohydroquisoneyl alpha-o-cresylchloroleate Chlorobenzyl-lauryl-chloro-resorcinol dodecenate Phenylbutylpyrogallyl alpha-chloropropylguaisylcinnamate Phenanthrenyl alpha-chlorodecylbenzylchlorolinoleate Chlorocatechylpropylchloroanthrenyl methylnaphthal-cyclo-oleate Dichlorostearylcatechyl octenate I Diiaromophenyl alpha-chlorostearylnaphthylmellsate Naturally occurring oils and waxes as such containing monohydric alcohol esters of organic acids have proved less satisfactory for use in this invention. The reason for this appears to be that these naturally occurring substances are a mixture of esters with naturally occurring impurities such as glycerides, high molecular weight alcohols, hydrocarbons, often nitrogen compounds, and other impurities. Some of the oils and waxes in this group are sperm oil and similar whale oils,wool fat, or wool grease, beeswax, carnauba wax, and candelilla wax. Sperm oil contains from 5 per cent to 25 per cent of glyceride, which makes it less satisfactory. It also contains an appreciable amount of free high molecular weight alcohols which are objectionable, since they also give relatively unstable derivatives of sulfurizing. The re-- moval of the monohydric or dihydric alcohol esters as such from the glycerides, free alcohol, and other impurities in the naturally occurring material is not presently commercially feasible.

When sperm oil is sulfurized, a product is ob tained which does not lend itself to refining as do the sulfurized relatively pure synthetic esters; consequently it cannot be used in a crankcase lubricant as an oiliness and film strength improver or as a sludge inhibitor because of its adverse effeet on color, emulsibility, and cloud test. The objectionable characteristics of the glycerides as described previously are in general also pertinent to the sulfurized and halogenated naturally occurring esters with only a few exceptions.

Wool fat or wool grease contains monohydric alcohol esters but is not entirely satisfactory for use in our invention because of naturally occurring impurities found therein. These consist of alphaalkali salts of fatty acids and free high molecular weight alcohols which yield relatively unstable sulfur derivatives. Sulfurized wool fat is not a desirable lubricating oil addition agent because it is not stable enough to allow refining, and when added to mineral oils, the resultant blend will not give a satisfactory emulsion or cloud test. Sulfurized wool fat darkens the color of the oil. It also breaks down at relatively low temperatures (compared with sulfurized synthetic esters) and releases HzS, which is objectionable. Hence wool fat would not give a satisfactory lubricating oil addition agent after suifurizing.

Beeswax contains 10 to per cent free fatty acid and 10 to 15 per cent hydrocarbons and is therefore unsuited for the production of a sulfurized addition agent for lubricating oils.

Candelilla wax contains, besides monohydric alcohol esters, about 10 per cent or more free fatty acid and about 50 per cent hydrocarbons. Carnauba wax contains some monohydric alcohol esters, but these are mixed with a complex variety of impurities such as free fatty acids, hydrocarbons, and free high molecular weight alcohols; and therefore neither candelilla nor carnauba wax is suitable for use as lubricating oil addition agents after being sulfurized.

However, the above-mentioned materials, namely naturally occurring wax containing saponifiable oils, sperm oil and similar whale oils, wool fat, wool grease, beeswax, carnauba wax, and candelilla wax do contain considerable quantities of high molecular weight acids (free and combined) which are suitable for use in our invention after saponification and separation of the acids and esterification with a monoor di-hydric phenol. This renders usable the valuable acids of the naturally occurring waxes and wax-containing saponifiable oils. We believe this is largely due to the decomposition of glycerides and removal of the glycerol present in some of these materials, but we do not wish to be bound by this supposition but only by the appended claims interpreted as broadly as the prior art permits.

The sulfurization of our phenolic esters may be accomplished by heating the synthetic ester with sulfur or a halide of sulfur in the presence or absence of a solvent. The temperature used depends on the particular synthetic ester. About 350 to 380 F. is used on esters derived from unsaturated acids and about 380 to 450 F. and higher may be used on saturated esters. Volatile hydrocarbons or relatively non-volatile neutral oils may be used as solvents for the ester in the sulfurizing step. The more volatile solvents of this type may be removed by distillation with steam or in a vacuum while the higher boiling neutral oils may be left in the sulfurized ester if they are taken into consideration when subsequent blends are made.

In sulfurizing our phenolic esters we may use elemental sulfur or various compounds of sulfur including sulfur monochloride, sulfur dichloride,

phosphorus pentasulflde, phosphorus trisulfide, polysulfides, and the like. Each of these reagents gives somewhat different products. Further-.

j er temperatures.

i ture within certain limits.

especially where bearing metals sensitive to corrosion are employed, our product containing only inactive sulfur is preferred.

Various factors must be considered in the preparation of our halogenated sulfurized phenolic esters containing active and inactive sulfur:

1. Reagents-In general for the preparation of halogenated sulfurized phenolic esters containing active sulfur, we prefer to use elemental sulfur combined with short times of heating and low- The sulfur compounds-such as chlorides of sulfur and sulfides of phosphorus are more likely to give products containing only inactive sulfur and are not so flexible with regard to product, other factors being constant. It is possible, however, at lower temperatures and with shorter periods of heating especially in solvents. to obtain active sulfur containing products using small amounts of sulfur. By controlling reagents and conditions we are able to obtain sulfur bearing derivatives with 2 to 20 per cent or more sulfur. tain products containing active sulfur or containing only inactive sulfur.

For any given sulfur content, we may ob- 3. Temperature.-Higher temperatures tend to fix .the sulfur in inactive combination and are used'when a stable halogenated sulfurized synthetic ester is desired. Use of lower temperatures with'the same reagents and otherwise the same conditions gives products containing active sulfur which are especially useful for cutting oils and extreme pressure gear lubricants when blended with hydrocarbon oils and other ingredients.

4. Time.-We heat our reactants for. a relatively short time to produce materials with active sulfur and for a relatively long time to obtain only inactive sulfur in our products. A short time at a high temperature may be selected which is the equivalent of a longer time at a lower tempera- There is, however, a most suitable range of temperature below which the time required is unreasonably long,

5. Solvcnts.-Inert solvents may be employed;

and, in general, they have the effect of limiting the highest temperature used in 'a particular sulfurization. If the solvent does not dissolve the sulfur or sulfur compound appreciably, the rate of reaction is slower and the formation of products containing active sulfur is favored. If the solvent dissolves the sulfur or sulfur compound,

, the reaction proceeds more rapidly; and products containing only inactive sulfur are more readily obtained.

6. Unrefined products are more likely to contain active sulfur than refined products. We vary the quantities of refining reagents, for example, sulfuric acid and clay, and also their concentration, time, and temperature of contact, etc., to

8 obtain thorough refining when a very stable product is desired. The refining may be milder or even omitted when an active sulfur product is sought.

7. Pressure-Under superatmospheric pressure the sulfur is more stably fixed in the same time and under the otherwise same conditions, and this is useful modification of our process in order to obtain products containing only inactive sulfur.

While there is no specific limitation to th amount of added sulfur in the form of halogenated sulfurized phenolic esters that should be used in preparing different lubricants, usually 1 to 4 per cent or more may be used for cutting oils; and about .5 to 2.5 per cent or more will usually be sufiicient for gear and other extreme pressure lubricants. As little as .001 per cent or a little less and up to .25 per cent or more may be used in oils for use in automobile crankcases.

The above ratios of sulfur to the petroleum base oil for its different uses .are not intended to limit the scope of this invention, since smaller or larger que. \tities may be used in any case with results which are partially satisfactory. They are given because generally speaking the optimum results can be obtained. by using the ratios within the limits that are suggested.

The hydrocarbon oils which are used in blending with the halogenated sulfurized phenolic esters are not limitedto the hydrocarbon oils cited in the examples but are to include any oil of any type or viscosity such as may be required by the lubricant in question. These different types of oils may be unrefined mineral oil or oil refined by any method, such as by the use of acids, alkalis, or solvents, or any combination of said refining processes. Other types are synthetic oils made by polymerization of similar processes and hydrogenated oils.

Sulfur dioxide and carbon dioxide have been mentioned as agents for blowing halogenated sul-' furized synthetic esters and it is to be understood that the inventors are in no way limited to any particular refining process and that other gaseous or liquid refining agents as nitrogen or alkali solutions and acid solutions may be used in refining halogenated sulfurized phenolic esters of certain character and for certain purposes.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

We therefore particularly point out and distinctly claim as our invention:

1. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion, sufilcient to increase the film strength of the oil, of a halogen-bearing sulfurized ester of a phenol and an unsaturated organic acid, said ester being ulfurized with a phosphorus.

2. A lubricant comprising in combination a major proportion of an oil lubricating viscosity and a minor proportion, sufficient to increase the film strength of the oil, of a halogen-bearing sulfurized ester of a phenol and an unsaturated organic acid, said ester being sulfurized by phosphorus pentasulfide.

3. A lubricant comprising in combination a major proportion of an oil of lubricating viscosity and a minor proportion, sufficient to increase the film strength of the oil, of halogenated sulfurized phenyl oleate.

2,433,853 9 4. A lubricant comprising a combination a ma- REFERENCES CITED Jor proportion of an on of lubricating Viscosity The following references are of record in the and a minor proportion, sufficient to increase the me of this patent, film strength of the oil, of halogenated sulfurized phenyllinoleate. 5 UNITED STATES PATENTS 5. A lubricant comprising in combination a ma- Number Name Date jor proportion of an oil of lubricating viscosity 2 124 598 Turner July 26 1938 and a minor proportion, sufficient to increase the 2153496 Berger et aL Apr 1939 film strength of the oil, of halogenated sulfurized 2'179062 Smith 1939 phenyl esters of the acids naturally occurring in 10 2186646 'g' Jam 1940 sperm 2:217:764 Morway et al Oct. 15, 1940 BERT LINCOLN- 2,31s,o13 Prutton May 4, 1942 WALDO STEINER- 2,357,211 Lincoln et a1 Aug.29,1944

Certificate of Correction Patent No. 2,433,853. January 6, 1948.

t BERT H. LINCOLN ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 8, lines 62 and 63, claim 1, after the word phosphorus and before the period insert sulphide; line 65, claim 2, after oil insert of; column 9, line 1, claim 4, for a after comprising read in; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 30th day of March, A. D. 1948.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.