US2367435A - Compounded oil and process of preparing the same - Google Patents

Description

Patented Jan. 16, 1945 COMPOUNDED OIL AND PROCESS OF PREPARING THE SAME Paul M. Ruedrich, Berkeley, Calif., assignor to Tide Water Associated Oil Company,- San Francisco, Calif., acorporation of Delaware No Drawing. Application January 9, 1943,

Serial No. 471,894

23 Claims.

This invention relates to improvements in lubricating oils and has for a principal object the provision of a lubricating oil having superior non-sludging characteristics when employed under the conditions of high temperature and pressure met in internal combustion engines.

Another object of the invention is to provide a lubricant which is non-corrosiveto the metal surfaces of an engine, especially to alloy bearmgs.

A further object is the purification of sulphonic acids and sulphonic soaps to render the same more suitable for use as additives to lubricating oils. Q

Other objects of the invention will be apparent in the following disclosure.

In the lubrication of high speed Diesel engines problems relative to adequate oiliness, carbon formation, prevention of ring-sticking, and wear are multitudinous. Modern aircraft engines offer similar problems to a great extent, although such problems are present at least to some extent in most internal combustion engines. solution of these problems it has become more or less common practice to incorporate metal soaps in the lubricating oil supplied to the crankcase of these engines. Among the soaps commonly employed alkaline earth sulphonates have been found particularly adapted to overcome.

most of the problems involved. However, these sulphonates, unless specially treated, cause undue corrosion to metal parts of the engine, es-

' pecially to bearings of the copper-lead alloy type. It is an object of this invention to produce al-- kaline earth sulphonates which, when added to lubricating oil in suitable amounts, will render the same highly resistant to such bearing corrosion and, to a great extent, free from ring-sticking, sludging, lacquer formation, and other unfailvorable characteristics common to lubricating o s.

In accordance with the invention it has been found that sulphonic acids derived from petroleum oils by treatment with concentrated sulphuric acid contain certain impurities which are the chief source of the corrosiveness generally experienced when their soaps are compounded with lubricating oils. If these impurities are removed or converted to non-corrosive compounds, the major portion'of the sulphonic acids produce alkaline earth soaps especially adapted for use in lubricating oils and oils blended with alkaline In the earth soaps of such purified sulphonic acids have vproven to be effective to a very high degree.

The liquid lubricant comprises a body of petroleum lubricating oil which contains dissolved alkaline earth metal soaps of the more stable constituents of petroleum sulfonic acids and alkaline earth metal soaps of the oxidation products of less stable constituents of petroleum sulfonic acids.

In the preparation and purification of the sulphonic acids, according to the invention, crude sulphonic acids derived from mineral oils are treated with potassium permanganate, preferably in an acidified aqueous solution, for a sumcient time to oxidize the more unstable compounds in the acids. For this purpose potassium permanganate in an amount equal'to approxi mately 0.01 to 0.5 equivalent weight per molecule of sulphonic acid is used, but in most cases best results are obtained when using from about, 0.1 to 0.2 equivalent weight. For example, since the equivalent weight of potassium permanganate is 31.6, a batch of 400 pounds of sulphonic acids having an average molecular weight of 400 (i. e., one pound-mole of sulphonic acids) may be treated with as little as 0.3 pound of potassium permanganate with noticeable effect, or the batch may be treated with as much as about 16 pounds of potassium permanganate without obtaining any considerable amount of deleterious reactions with the excess permanganate. Depending upon the nature of the sulphonic acids, best results usually will be obtained by treating such a batch of sulphonic acids with from about 3 to about 6 pounds of potassium permanganate. It is the purpose of the treatment, with permanganate to oxidize the more unstable components of the crude sulphonic acids and the exact quantity of permanganate for best results in each individual case may readily be determined by a skilled chemist by simple tests. For carrying out the treatment, an ordinary glazed or lead lined a itator equipped with means for mechanical or air agitation is suitable. However, various types of batch or continuous contacting apparatus may be used.

Although the reaction of the potassium permanganate with the unstable components may be. carried out; in various media, or even with dry permanganate by far the most satisfactory method is by contacting the sulphonic acids with the peracidified with a small amount of strong acid such as, for example, sulphuric acid. Care should be taken, of course, not to bring the permanganate into contact with concentrated strong acid, especially concentrated sulphuric acid, due to the danger of forming explosive mixtures. With efficient contacting the reaction of the potassium permanganate with the crude sulphonic acids takes place quite rapidly and, at ordinary temperatures, the reaction is nearly complete in several minutes. However, the reaction may be speeded up by applying a moderate degree of heat. For this purpose excellent results have been obtained using temperatures from 100 F. to 200 F., although temperatures somewhat higher or lower may be used. Also, in order to insure complete reaction it is well to continue the contacting for approximately one hour. After this treatment it will be found that the sulphonic acids are emulsified to a greater or less extent with the water present. They may be separated therefrom by the addition of some solvent such as alcohol or gasoline, the former uniting with the water of the emulsion and the latter uniting with the sulphonic acids. In either case two layers are formed, the non-aqueous layer containing the sulphonic acids. The sulphonic acids are then freed from any solvent and converted to calcium or other alkaline earth soaps by treatment withlime or with the hydroxide of magnesium, strontium, or barium, or in any other desired manner, such as for example, first forming the sodium soaps and converting these to the alkaline earth soaps by treatment with suitable alkaline earth metal salt. Alternately, the emulsion of purified sulphonic acids and water may be treated with lime or other alkaline earth metal hydroxide or water-soluble alkaline earth metal salt, such as for example calcium chloride, to form soaps of the sulphonic acid present and the resulting soaps are then separated from the water and inorganic salts by the use of alcohol or other diluent or. by the use of a solvent for the soaps.

Generally, it will be found that sulphonic acids prepared as the above, and the soaps made therefrom, will contain a small percentage of'manganese in chemical combination therewith. However, this is not to be regarded as due to the formation of manganese soaps with the sulphonic radicals present in the original acids. Rather, it is in general the result of the addition of manganese to the more reactive molecules at the point of oxidation. If desired, the purified sulphonic acids may be freed from the manganese by repeated extractions with an aqueous solution of a strong acid. However, the removal of the manganese is not necessary as its presence improves to an appreciable extent the stability of the alkaline earth'soaps made therefrom.

Petroleum sulphonic acids which may be used advantageously to produce the purified alkaline earth sulphonates of this invention are preferably of the oil-soluble type which are obtained, for example, in the treatment of relatively heavy mineral oils, preferably so-called naphthenic oils such as California gas oils or lubricating oils, with concentrated or preferably fuming sulphuric acid. In this kind of treatment two types of sulphonic acids are produced, namely, so-called green sulphonic acids which are substantially oilinsoluble and mahogany acids which are oil-soluble The mahogany acids are preferred, although the green acids may also yield certain oil-soluble soaps which are applicable to the purposes of the invention Other oil-soluble hydrocarbon sulphonic acids suitable for the'invention may be produced by the sulphonation of variou hydrocarbons provided the number of carbon atoms is sufllcient to render the resulting alkaline earth soaps soluble in the lubricating oil.

To form the oils of this invention alkaline earth sulphonates prepared as above, preferably without removing the combined manganese, are added to lubricating oils of suitable viscosity in the proportion of from 0.1% to 5%, the proportion of 1% to 5% being preferred. A very convenient method of preparing the oil of the desired percentage of soap is to prepare a stock solution of .oil containing more than 5% and preferably as much as 20% or more of soap and use this stock solution for making blends of any desired viscosity by blending the stock solution in proper amounts with oil of required viscosity.

An alternate procedure of preparing oils according to the invention is to start with the crude sulphonic acids or sulphonate soaps dissolved in the desired lubricating oil. The oil containing the crude acids or soaps is then treated with acidified potassium permanganate. After agitation for a suflicient length of time the oil is freed from water and inorganic salts. The oil thus treated will contain purified sulphonic acids, any soap present having been decomposed by the mineral acid used. After separation of the acid and excess permanganate, suflicient lime or other-alkaline earth hydroxide is added to combine with the sulphonic acids present. Excess lime is removed by settling, filtering, or centrifuging. The finished oil will have substantially all the desired properties of oil prepared by treating the acids separately with permanganate and adding soaps of the treated acids to the oil as described above.

The base oil to which the purified alkaline earth sulphonates may be added may be of the .so-called parafiinic, naphthenic, or mixed-base tage, important in some applications, of having a somewhat higher viscosity-temperature coefficient. By the use of the sulphonic soaps of the present invention the corrosiveness of the parafiinic oils is reduced to a minimum, and it is possible to retain any advantage of low viscositytemperature coefficient inherent in parafiinic oils without the attendant corrosiveness ordinarily experienced.

The alkaline earth sulphonates affect the viscosity of mineral oils but little when blended in proportions of 5% or less. Hence, the choice of the proper viscosity for the base oil depends upon the application intended for the finished oil. In the lubrication of the modern high speed Diesel engine oils having S. A. E. viscosity rating of 10, 20, and 30 are usually employed. For aircraft engines, oils of S. A; E. 40 and 50 and even higher are commonly used. However, due to the added oiliness imparted to the oil by the sulphonic soaps, greater ranges of viscosity are made Table I the soap is present in amount of 1.0% to 5.0%. 5. A lubricant according to claim 1 in which 031mm g of the soap is present in amount in excess of 5%, son 12:33 5 2 igg g g ggigf thus making the lubricant suitable for use as a p phonic wa with the 5 stock solution to be later diluted with additional Invention petroleum oil. Q 6. A liquid lubricant for internal combustion Engmetype 3L g g B lg g engines comprising a body of petroleum lubricatengine. engine. ing oil containing dissolved alkaline earth metal 'ggg fi-g 10 soaps of petroleum sulphonic acids, the normally Hours ,run m i more unstable components of said acids having para no, 138310011 naphthemm" mphthemc been oxidized and retained in the lubricant in %A.E%grade go go oxldlzed form.

er cen soap r Appearance oipiston Covered%with 100% clean after A l quid lubricant for internal combustion hard, black wiping. in engines comprising a body of petroleum lubricatac Hen Ring grooves Deep aymmgrd very little so" me Oll containing dissolved alkaline earth metal carbon behind carbon. soaps of mahogany sulphonic acids, the normally llnll'S.

Piston liner .Q Free from abra- Free from abramore mlsliable componepts sald aclds having sons. sions. been oxidized and retained in the lubricant in Oil filter Fairlyt heavlydde- N0 sludge. no oxidized form 1 posi 0 sn ge. Cu-Pb bearings, loss, mgs. 291... 64. 8. A liquid lubricant for internal combustion engines comprising a body of petroleum lubri- Table II Calcium soap or 7 Calcium soap oi sulphonic acids Soap used No additive untreated sultreated in acphonic acids cordance with invention Engine type 0m V-8 gigord V-8 zgiord V-8.

2,566IIIIIIIIIIII 2,500. so 5o 50. v

50% paraflinlc.-. 50% parafilnicm 50% parafllnic.

%% naphthenic. gg% naphthenic 33% naphthenic.

Percent soap crankcase temp., "F.

Oil change Cleanliness oi pistons Carbon deposits top of pistons, gms

Carbon deposits, bottom oi pistonsfi ms.

Viscosity of oil, before, S. U. 210

Viscosity of oil, after, B. U. 210 F.

Acidity of oil. before KOH/gm Acidity of oil, alter, lIOH/gm The above tabulations illustratethe freedom from bearing-corrosion obtained by oils prepared in accordance with the invention. Also, they demonstrate the superior properties with respect to freedom from sludging, carbon-formation, and ring-sticking.

An additional efiect noticeable in engines using fuels compounded with tetraethyl lead is the absence of lead-salt deposits customarily round in the crankcase and on the underside of the pistons wherethis type of fuel is used. Such deposits are at times particularly troublesome due to the abrasive action of the salts on the moving surfaces of the engine. Oils compounds with metallic soaps not prepared in accordance with the present invention have proven ineflective in preventing these deposits. It is, therefore, an ob- Ject of the invention to produce a lubricating oil which will effectively restrain the formation of lead-salt deposits in the crankcases of engines using leaded fuels.

I claim: Y

1. A liquid lubrlcant'for internal combustionengines comprising a body of petroleum lubricateating oil containing dissolved alkaline earth metal soaps of the more stable constituents of petroleum sulphonic acids and alkaline earth metal soaps of the oxidation products of less stable constituents of petroleum sulphonic acids.

9. A lubricant according to claim 8, in which the alkaline earth metal is calcium.

10. A lubricant according to claim 8, in which the alkaline earth metal is calcium, and the soaps are present in an amount greater than 0.1%.

11. A lubricant according to claim 8 in which the soap contains'a small percentage of manganese in chemical combination therewith.

12. A liquid lubricant for internal combustion engines comprising a body of petroleum lubricating oil containing dissolved alkaline earth metal soaps of organic acids oi the composition obtained by treating petroleum sulphonic acids with from 0.01 to 0.5 equivalent or potassium permanganate and retaining in the acids the organically combined manganese.

13. A non-corrosive lubricating oil of superior non-sludging characteristics when employed under the conditions or high temperature and pressure met in internal combustion engines comprising a body of petroleum lubricating oil contain- 70 ing dissolved alkaline earth metal soaps oi the mote stable constituents of mahogany sulfonic acids-and alkaline earth metal soaps or the oxidation products or less stable constituents of mahogany sulfonic acids.

14. The method or preparing a lubricating oil having superior antisludsine' and anticorrosion properties which comprises; treating sulphonic acids with sufllcient potassium permanganate to oxidize the more unstable components of said acids, separating the treated sulphonic acids irom inorganic material, forming alkaline earth metal soapsoi the resulting acids, and dissolving said soaps in a petroleum lubricating 011.

15. The method of claim 14 in which the amount of potassium permanganate used is be- 7 tween 0.01 and 0.5 equivalent per molecule of sulphonic acid treated.

16. The method of claim 14 in which the amount or potassium permanganate used is be: tween about 9.1 and about 0.2 equivalent per molecule of sulphonic acid treated.

1'7. The method claim, 14 in which the alkaline'earth metal is calcium.

' 18. The method of preparing a lubricating oil vhavingsuperior antisludging and anticorrosion properties which comprises: treating petroleum sulphonic acids with suflicient potassium per- 'manganate to oxidize the more unstable components of said acids, separating the treated sulphonic acids from inorganic material, forming alkaline earth metal soaps of the resulting acids, and dissolving said soaps in a petroleum lubrieating oil.

19.- The method oi! preparing a lubricating oil having superior antisludging and anticorrosion acids with sumcient potassium permanganate in an acidified aqueous solution to oxidize the more unstable components of said aclds,.separating the treated sulphonic acids from the aqueous phase, forming alkaline earth metal soaps of the resultingacids, and dissolving said soaps in a petroleum lubricating 011.

. method 01' preparing alubricating oil having superior antisludging. and anticorrosion properties which comprises: treating a lubricating oil containing dissolved sulphonic acids with an acidified aqueous solution of potassium permanganate in suillcient amount to oxidize the more unstable components or said acids, separating the resulting oil irom'the aqueous phase, and then converting the acids contained in the oil to their corresponding alkaline earth metal soap.

21. The method of preparing a lubricating oil having superior antisludging and anticorrosion properties which comprises: treating sulphonic properties which comprises: treating sulphonic acids with suflicient potassium permanganate to oxidize the more unstable components 01 said acids, separating the treated sulphonic acids from inorganic material, extracting the thus treated sulphonic acids with a dilute strong mineral acid to remove combined manganese, forming alkaline earth metal soaps oi the resulting acids, and dissolving'said soaps in a petroleum lubricating'oil.

22. In a process wherein sulphonic acids are partially oxidized to improve their stability and the thus treated acids are converted into alkaline earth metal soaps which are dissolved in a petroleum lubricating oil, the combination oi,

PAUL M. nonunion.