US3273981A - Anti-wear oil additives - Google Patents

Description

United States Patent 3,273,981 ANTI-WEAR OIL ADDITIVES Michael J. Furey, Berkeley Heights, N.J., assignor to Esso Research and Engineering Company, a corporation of Delaware N0 Drawing. Filed July 16, 1963, Ser. No. 295,546 7 Claims. (Cl. 44-66) The present application is a continuation-in-part of Serial No. 263,425, filed March 7, 1963, entitled Oil Compositions Containing Anti-Wear Additives, now Patent No. 3,180,832, inventor, Michael I. Furey, which, in turn, is a continuation-in-part of Serial No. 816,704, filed May 29, 1959, entitled Oil Compositions Containing Anti-Wear Additives, now abandoned, inventor, Michael J. Furey.

The present invention is generally concerned with a novel class of lubricity additive mixtures, additive concentrates, and oleophilic liquid compositions containing these additive mixtures. The invention is more specifically concerned with improving the lubricity of hydrocarbon liquids such as gasolines, aviation turbo fuel, kerosene, diesel fuel, lubricating oil and mineral lubricating oils. Other base fluids include liquid carbohydrates and esters such as dioctyl sebacate and didecyl adipate. The present invention also contemplates the use of the lubricity additive mixtures in solid products such as paraffin wax, lubricating grease and Carbowax. The invention in one specific aspect relates to improving the lubricity of middle distillates, particularly jet fuels. The lubricity additive mixtures of the present invention comprise a dicarboxylic acid and a partial ester of a polyhydric alcohol.

The lubricity additive mixtures of the present invention preferably comprise a partial ester of a polyhydric alcohol, and dicarboxylic acids that are obtained by the polymerization of dienoic or trienoic monocarboxylic acids. Thus, the invention is concerned with a novel class of lubricity additive mixtures which are specifically adapted for use in conjunction with oleophilic liquids such as hydrocarbon lubricants and jet fuels. In accordance with a specific adaptation of the present invention, middle distillate compositions such as jet fuels are improved with respect to their lubricity by incorporating therein an effective amount of a mixture of a partial ester of a polyhydric alcohol, and a dimer of linoleic acid.

Many oil compositions are designed for lubricating under boundary conditions (e.g. crankcase oils, aviation oils and gear oils) where the prevention of wear of the metal surfaces under heavy loading is a serious problem. One common example of such heavy loading occurs in the operation of the valve lifter mechanism of gasoline engines. Here, pressures of 50,000 to 100,000 p.s.i. can occur between the valve lifter and its actuating cam, and metal Wear is accordingly high. It has now been found that metal wear can be significantly reduced by adding to an oleophilic liquid such as a mineral oil lubricant, a mixture of a dicarboxylic acid and a partial ester of a polyhydric alcohol. It is preferred that the dicarboxylic acid be characterized by having at least 9 carbon atoms, preferably 12 to 42 carbon atoms, between the respective carboxylic groups. A particularly desirable mixture is a dimer acid such as linoleic dimer and sorbitan monooleate.

Other additives, of course, may be added to the oil compositions of the present invention to form a finished oil. Such additives include oxidation inhibitors such as phenot-hiazine or phenyl a-naphthylamine; rust inhibitors such as lecithin or petroleum sulfonates; detergents such as the barium salt of isononyl phenol sulfide; pour point depressants such as copolymers of vinyl acetate with fumaric acid esters of coconut oil alcohols; viscosity index imnrovers such as polymethacrylates; etc.

3,2 73,981 Patented Sept. 20, 1966 ICC The preferred dicarboxylic acids from which the esters are made are those acids which contain at least 9 carbon atoms between the respective carboxylic groups. It is very desirable that the number of carbon atoms between the carboxylic groups be in the range from about 12 to 42. Specific examples of these acids are the dimer of linoleic acid, dodecanedioic acid, and dicyclopentadiene dioic acid. While the foregoing acids are preferred, similar dicarboxylic acids such as VR-l described in US. 2,833,713 and D-SO described in U.S. 2,470,849 may be used. The dienoic or trienoic monocarboxylic acid, that is polymerized to give the dicarboxylic polymer, can have from 12 to 30 carbon atoms and must have at least two double bonds in its longest carbon chain, the bonds being separated by 3 carbon atoms, e.g. 9,12-octadecadienoic acid and 9,12,lS-octa-decatrienoic acid.

The mixture of high molecular weight unsaturated fatty acids comprises monomers, dimers, trimers and higher polymers in the ratio of from about 45 to about 55% of a monomers and dimers fraction having a molecular weight in the range of from about 300 to 600, and from about 45% to about 55% of a trimers and higher polymer fractions having a molecular weight in excess of 600. The fatty acid polymers result in part from a thermal polymerization of fatty acid type constituents of the castor oil, and in part from other reactions, such as the intermolecular esterification, of such acid to form high molecular weight products. The acid mixture, which is mainly a mixture of polymeric long chain polybasic carboxylic acids, is further characterized by the following specifications:

Acid No -164- Saponification No. -186 Free fatty acids "percent" 75 to 82 Iodine value 40 to 55 Nonsaponifiables percent 2.5 to 5 A fatty acid mixture such as above described is marketed by the W. C. Hardesty Company under the trade name D-SO Acids, and as VR-l Acids by Rohm & Haas Company.

Thus, as pointed out, a particularly desirable dicarboxylic acid to be used in forming the reaction product of the present invention is a dimer of linoleic acid.

The formation of this dimer acid may be illustrated as follows:

In general, the dimer acid of linoleic acid with which the present invention is concerned is a C dimer acid and is described in US. Patent 2,424,5 88 issued July 29, 1947, and entitled Lubricant Composition; inventors, W. J. Sparks et al. It is to be understood that the dimer acid a is not necessarily 100% dimer acid. For example, the following compositions may be used:

Composition, Wt. Percent Thus, in essence, the presence invention uses a mixture of A-t-B in an oleophilic fluid to improve anti-scuffing properties where A is a polybasic acid, or a polybasic acid ester made preferably by reacting the acid with C C monohydric alcohols; while B is a partial ester of a polyhydric alcohol and a fatty acid.

Specific examples of the foregoing category A compounds are: dimer acids (e g. dilinoleic acid); straight chain aliphatic dibasic acids, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioic acid; benzene polycarboxylic acids, such as phthalic acid, isophthalic acid, terephthalic acid, hemimellitic acid, trimellitic acid, trimesic acid, prehnitic acid, mellophanic acid, pyromellitic acid, benzene pentacarboxylic acid and mellitic acid; and others such as diphenic acid, diglycolic acid, d-tartaric acid and cis-4-cyclohexene acid.

Examples of alcohols (C C which may be used to .esterify these polybasic acids if desired are methanol,

ethanol, propanol, isopropanol, butanol, isobutanol, and pentanol. Other alcohols are benzyl alcohol and cyclohexanol. These esters may also be mixed esters such as monomethyl monopropyl ester of the dimer of a dicarboxylic acid such as the dimer of linoleic acid.

Compounds in category B include the C to C fatty acid partial esters of aliphatic polyhydric alcohols having about 3 to 12, preferably 3 to 8, carbon atoms and about 2 to 8, e.g. 3 to 6 hydroxy .groups per molecule. Preferred materials are the monoand diesters of C to C alcohols having 3 to 6 hydroxyl groups and prepared from C to C fatty acids. The above type of partial esters include the partial esters of the mono-dehydrated aliphatic polyhydric alcohols as well as partial esters of non-dehydrated aliphatic polyhydric alcohols. Examples of these partial esters are: sorbitan monoleate, glyceryl monooleate, pentaerythritol monooleate, the dioleates of sorbitan, mannitan, pentaerythritol and related polyhydric alcohols, the corresponding partial stearic and palmitic acid esters of these alcohols, and partial esters of these alcohols made from mixtures of these fatty acids. Agents of this type are well known in the art, e.g. U.S. 2,434,490 and 2,716,611.

It is important that at least two hydroxy groups and preferably more be on the carboxylic acid ester. Thus, partial esters of the following compounds could be used: mannitol, sorbitol, dulcitol, inositol, glucose, fructose, pentaerythritol and glycerol. Furthermore, partial esters of some of the above polyols in partly dehydrated form (e.g. sorbitan) could also be used. The preferred acid is oleic and more particularly the monooleate ester is preferred. This achieves oil solubility while leaving the maximum number of free hydroxyl groups left. Of course, other fatty acids (e.g. 830 carbon atoms) and diesters (e.g. sorbitol dioleate) may also be used.

While the over-all objective of the present invention is to improve the anti-scuffing and anti-wear properties of fluids, one particular objective of the present invention is to improve the lubricity of distillate fuels boiling in the range from about 50 to 750 F. Thus, in accordance with the present invention, middle distillate compositions are improved with respect to their lubricity by incorporating therein an effective amount of a mixture of the present invention.

It is well known in the art to improve the quality of jet fuels by various refining techniques in order to remove from these fuels undesirable constituents such as polar compounds, sulfur compounds, and nitrogen compounds. These compounds are removed in order to improve engine performance and lengthen the hours the engine can be operated without major overhauling, but it has been found that when the viscosity of these fuels is relatively low and wherein certain impurities are removed to below a maximum, the finished pure fuel lacks lubricity, which is essential in order to keep the engine parts from excessive wear and a relatively short life. These engine parts among others comprise the fuel pumps, the gears, the bearings and any other parts wherein scuffing and wear is a problem.

Such fuels include aviation turbo-jet fuels, rocket fuels (MILR-25576B), kerosenes, diesel fuels and heating oils. Aviation turbo-jet fuels in which the mixture of the present invention may be used normally boil between about 50 and about 550 F. and are used in both military and civilian aircraft. Such fuels are more fully defined by U.S. Military Specifications MIL-F-5624F, MILF25656A, MIL-F-25554A, MILF25558B, and amendments thereto, and in ASTM D165562T. Kerosenes and heating oils will normally have boiling ranges between about 300 and about 750 F. and are more fully described in ASTM Specification D396-48T and supplements thereto, where they are referred to as No. 1 and No. 2 fuel oils. Diesel fuels in which the mixture of the present invention may be employed are described in detail in ASTM Specification D97535T and later versions of the same specification.

Particularly desirable base fuels wherein the present additive mixtures are most effective are those base fuels wherein the viscosity is below about 3 centistokes and which fuels are substantially free of polar compounds, sulfur compounds, and nitrogen compounds. In essence, the concentration of these compounds is less than about 0.01% by weight which is secured when the jet fuel is highly refined, such as by hydrofining.

The additives of the present invention may be employed in conjunction with a variety of other additives commonly used in fuels such as those set forth above. Typical of these additives are rust inhibitors, anti-emulsifying agents, corrosion inhibitors, anti-oxidants, dispersants, dyes, dye stabilizers, haze inhibitors, antistatic agents and the like. It will frequently be found convenient to prepare additive concentrates for use in the various types of fuels and thus add all of the additives simultaneously.

Thus, in accordance with the present invention, polybasic acids or esters of these acids, and a partial ester of a polyhydric alcohol comprise new valuable additive mixtures for jet fuels. A particularly desirable mixture comprises a dimer linoleic acid and sorbitan monooleate.

If the additive mixtures of the present invention are used as an additive concentrate, the concentrate may consist essentially of from about 25 to 75% of the addi tive mixture, the remainder being a satisfactory solvent such as kerosene, a Varsol, a naphtha and the like. The preferred concentrate contains about 50 to 60% of the additive mixture in the solvent.

When the additive mixture is used in conjunction with oleophilic liquid, the concentration may vary appreciably. For example, when the additive mixture is used in a fuel, the concentration is in the range from about 0.001 to 1.0% by weight, preferably in the range from about 0.01 to 0.5% by weight. On the other hand, if the additive mixture is used with a hydrocarbon lubricating oil, the concentration may vary in the range from about 0.001 to 4.9% by weight, preferably in the range from about 0.1 to 2.0% by weight. It is preferred that the mole ratios of a partial ester of a polyhydric alcohol and the dicarboxylic ester be about 1/1 although the ratios may vary from 0.5/1 to 1.5/1.

In ord r to further illustrate the invention, a number of tests were carried out using the additives of the present invention in base jet fuels and the load carrying capacity of the fuels determined.

As shown by the data below, the addition of 0.2% of the additive mixture increases the anti-scufiing properties of jet fuel as measured by the Ryder Gear Test (Ryder, E. A., ASTM Bulletin 184, 41 (1952)). The ratings represent the load in pounds/ inch of tooth width to produce a given amount (22 /2%) of gear scufiing.

EFFECT OF C DIMER ACID AND SORBITAN MONOOLATE ON RYDER GEAR PERFORM- ANCE OF JET FUEL Ryder rating Additive in jet fuel: 1 (lbs/in.)

None Ca. 400 01% C dimer acid-0.1% sorbitan monooleate 1790 0.1% C dimer acid 480 0.2% sorbitan monooleate 810 1 High isoparafiinlc fuel of 375500 F. boiling range, high thermal stability, W freezing point and low sulfur content.

As seen by the data in the above table, the addition of C dimer acid and sorbitan monooleate to jet fuel increased the Ryder scufii rating from about 400 lbs/in. to 1790 lbs/in. This is a substantial increase. Furthermore, it can also be seen that dimer acid alone has no significant eifect and that sorbitan monooleate by itself is rather mediocre.

The additive mixtures of the present invention, as pointed out heretofore, are also very effective in increasing the load carrying capacity of other fuels such as kerosene, and synthetic oils as well as mineral lubricating oils. The synthetic oils will include diester oils such as di(2-ethylhexyl) sebacate; complex ester oils and silicone oils; sulfide esters; organic carbonates; and other synthetic oils known to the art.

What is claimed is:

-1. A hydrocarbon middle distillate boiling in the range from to about 750 F. containing dissolved therein between about 0.001 and about 1.0 wt. percent of an additive mixture comprising a polycarboxylic acid of between about 9 and about 42 carbon atoms per molecule between the carboxylic acid groups and a partial ester of a polyhydric alcohol of between about 3 and about 8 carbon atoms per molecule and containing between about 3 and about 6 hydroxyl groups per molecule and a C to C fatty acid.

2. A hydrocarbon middle distillate as in claim 1 wherein the additive mixture is present in an amount between about 0.01 and about 0.5 wt. percent.

3. A hydrocarbon middle distillate as in claim 2 wherein the distillate is a jet fuel.

4. A hydrocarbon middle distillate as defined by claim 1 wherein said polycarboxylic acid is the dimer of linoleic acid.

5. A hydrocarbon middle distillate as defined by claim 1 wherein said polycarboxylic acid is dodecanedioic acid.

6. A hydrocarbon middle distillate as defined by claim 1 wherein said polycarboxylic acid is dodecanedioic dioic acid.

7. A hydrocarbon middle distillate as defined by claim 1 wherein said polycarboxylic acid is a dimer of linoleic acid and said partial ester is sorbitan monooleate.

References Cited by the Examiner UNITED STATES PATENTS 1,463,092 7/1923 Pelly 252-56 2,334,158 11/1943 Von Fuchs et a1 25256 2,394,909 2/1946 Gleason 252-56 2,424,588 7/1947 Sparks et al 25256 2,767,144 10/1956 Gottshall et a1. 44-66 2,833,713 5/1958 Lemmon et al. 252-32.7

DANIEL E. WYMAN, Primary Examiner.

J. E. DEMPSEY, P. KONOPKA, Assistant Examiners.

Claims (1)

1. A HYDROCARBON MIDDLE DISTILLATE BOILING IN THE RANGE FROM 50* TO ABOUT 750*F. CONTAINING DISSOLVED THEREIN BETWEEN ABOUT 0.001 AND ABOUT 1.0 WT. PERCENT OF AN ADDITIVE MIXTURE COMPRISING A POLYCARBOXYLIC ACID OF BETWEEN ABOUT 9 AND ABOUT 42 CARBON ATOMS PER MOLECULE BETWEEN THE CARBOXYLIC ACID GROUPS AND A PARTIAL ESTER OF A POLYHYDRIC ALCOHOL OF BETWEEN ABOUT 3 AND ABOUT 8 CARBON ATOMS PER MOLECULE AND CONTAINING BETWEEN ABOUT 3 AND ABOUT 6 HYDROXYL GROUPS PER MOLECULE AND A C12 TO C22 FATTY ACID.