US2900339A

US2900339A - Process for preparing lubricant compositions and concentrates therefor

Info

Publication number: US2900339A
Application number: US721127A
Authority: US
Inventors: Lowe Warren
Original assignee: California Research LLC
Current assignee: California Research LLC
Priority date: 1958-03-13
Filing date: 1958-03-13
Publication date: 1959-08-18
Anticipated expiration: 1976-08-18

Description

Aug. 18, 1959 w. LOWE PROCESS FOR PREPARING LUBRICANT COMPOSITIONS AND CONCENTRATES THEREFOR Filed March 13, 1958 R V. \V o E /l T N qwm NN R mm WM 0 T 53.5w R T 5 68 E UI\ M A 5300mm I ww Y km \mw m t o ozEGEEj E vw miow 2 9u uj zti 10.55. E f uz 2 2? t 3 3 States PROCESS FUR PREPARING LUBRICANT CUMPU- SITIUNS AND CONCENTRATES THEREFOR Application March 13, 1958, Serial No. 721,127 Claims. arm-33.4

The present invention relates to a superior new process for preparing lubricant compositions and concentrates therefor. More particularly, the invention is concerned with a novel method of producing additive type lubricating oil compositions and concentrates for preparing them which contain greatly increased amounts of the effective additive in stable combination.

Lubricating oil compositions are subject to deterioration by oxidation which results in the formation of corrosive products, particularly in modern internal combustion engines where stringent operating conditions are encountered. These corrosive products attack the bearings and other metal surfaces in the engine, and additives are ordinarily employed to inhibit their corrosivity. In order for the additives to perfonn effectively during the service of the lubricating oil composition, it is important that adequate amounts of the additive be present at all times in stable combination with the lubricating oil base. Still larger proportions of additives are required, of course, in the concentrates with which the corrosion inhibited lubricating oil compositions are prepared.

Unusually effective corrosion inhibited lubricating oil compositions comprising lubricating oil and a phthalic acid have been described in application Serial No. 478,517, Lowe and Stewart and application Serial No. 478,838, Stewart and Lowe, both filed December 29, 1954, and now both abandoned. Although the compositions described in these applications have very greatly improved corrosion inhibiting properties compared to previously known lubricant compositions containing conventional corrosion inhibitor additives, the phthalic acids are so slightly soluble in lubricating oils that there is a limit to the amount that can be stably dispersed by simply adding them to the base oil. The desirability of a process whereby larger amounts of the phthalic acids can be combined in stable form with an oil of lubricating viscosity is, therefore, even greater in the case of these very important types of corrosion inhibited lubricating oil compositions and concentrates from which they are prepared.

It has now been found that stable dispersions of phthalic acids in oils of lubricating viscosity can be prepared by a process which comprises reacting a phthalic acid with a tertiary amine, combining the reaction mixture thus obtained with an oil of lubricating viscosity, heating the combined oil and reaction mixture to liberate the tertiary amine and separating the tertiary amine and the resulting dispersion of phthalic acid in oil of lubricating. viscosity.

In the superior new process of this invention as described above, there is provided a remarkably straightforward means for the production of lubricating oil compositions and concentrates for preparing them which contain substantially larger amounts of phthalic acid than have heretofore been possible. Particularly in the case of lubricating oil concentrates, the outstanding advantages of the present process are most appreciated, since it is of the utmost importance for practical reasons that 2,900,339 Patented Aug. 18, .1959

a pressure and the separations are made by the use of conventional procedures.

Still another outstanding advantage of the process of the invention lies in the fact that the tertiary amine may be recovered and recycled for further use. Although the tertiary amine is not an unusually expensive reagent, this provides more effective use of it, contributing to overall efiiciency, and gives a definite economic advantage to the process.

In the practice of the invention, the phthalic acid is first reacted with the tertiary amine, as already mentioned. The acid is thus converted to its tertiary amine salt. Although the tertiary amine may be employed in any amount sufficient to neutralize the acid, a stoichiometric excess is preferred. This insures complete reaction, and any excess tertiary amine is readily recovered in accordance with the process of the invention. Usually proportions of at least 20 to 40 moles of tertiary amine per mole of phthalic acid will provide a very suitable reaction mixture for dispersion in the lubricating oil. In a preferred embodiment the amount of tertiary amine employed is suflicient to dissolve all of the phthalic acid tertiary amine salt. amine has been found to act as a cosolvent for both the phthalic acid tertiary amine salt and the oil of lubricating viscosity with which it is combined. More thorough dispersion of the tertiary amine salt in the oil is thus possible.

The reaction of the phthalic acid with the tertiary amine in the present process is conveniently carried out at ordinary temperatures and under ordinary pressures. Room temperatures of about 77 F. are particularly suitable, since they require no heating or cooling of the reactants. Higher temperatures can be employed to accelerate the reaction and facilitate the dissolving of the tertiary amine salt. However, temperatures in excess of 600 F. are preferably avoided, since the phthalic acids tend to sublime when overheated. For similar reasons it is also desirable'that the reaction temperature not exceed the boiling point of the tertiary amine at the particular pressure employed during the reaction. Usually temperatures of from about F. to 500 F. are suitable. Where solvents such as benzene and toluene are employed, it is particularly convenient to allow the reaction mixture to reflux, thus maintaining temperatures at the boiling points of, the respective solvents.

The pressure at which the reaction is carried out may be either atmospheric, subatmospheric or superatmosphen'c. However, atmospheric pressures are preferred, since the need for pressure equipment or vacuum equipment is thus avoided.

The phthalic acid of the process may be either phthalic acid, isophthalic acid or terephthalic acid. These acids are commercially available and require .no detailed description here. For present purposes, the nonanhydrideforming benzene dicarboxylic acids such as isophthalic acid and terephthalic acid and their nuclear substituted analogues such as hexahydrometaphthalic acid, hexahydroparaphthalic acid and S-tertbutylisophthalic acid are preferred. The most suitable acids are the isophthalic acid and terephthalic acid, more particularly the latter, since they give lubricant compositions which are-unusually effective corrosion inhibitors.

The tertiary amine with which the phthalic acid is reacted may be any basic tertiary amine capable of forming thermally unstable. salts of the, phthalic acid. Such In such a case the excess tertiary tertiary amines maybe any of the well-known, commonly available types having the general formula in which R R and R may be the same or diflerent aliphatic, aryl, aryl aliphthatic or hydroxy aliphatic groups. Either two or all three of the valence bonds to these groups may be combined to form a single group as in the case of cycloaliphatic or heterocyclic tertiary amines. Preferably, the tertiary amines boil below about 600 F., the temperature which the phthalic acids tend to sublime. More particularly the preferred tertiary amines are those having the above formula in which R R and R contain a total of from 5 to 15 carbon atoms. Illustrative tertiary amines include triethylamine, N,N-dimethyl-N-benzylamine, N,N-dimethylaniline, N-methylpiperidine, pyridine, picoline, triethanolamine and the like. For present purposes, pyridine, picoline and triethylamine are preferred in the order mentioned for their particularly suitable physical characteristics and general availability. These tertiary amines illustrate the more suitable class of tertiary hydrocarbon amines containing a total of from 5 to 15 carbon atoms although the alkyl, hydroxyalkyl and heterocyclic aromatic tertiary amines of the abovementioned illustrative types are generally satisfactory.

As mentioned above, solvents may be employed in the reaction of the phthalic acid with the tertiary amine. This facilitates the handling of the reactants and can be I used to provide automatic temperature controls, if desired,

for the reaction. a

Any of the well-known types of oils of lubricating viscosity are suitably employed in the preparation of the lubricant compositions and lubricating oil concentrates in accordance with the process of the invention. They include hydrocarbon or mineral lubricating oils or naphthenic, paraftinic, and mixed naphthenic and paraffinic types. They may be refined by any of the conventional methods such as solvent refining and acid refining. Synthetic hydrocarbon oils of the alkylene polymer type or those derived from coal and shale may also be employed. Alkylene oxide polymers and their derivatives such as the propylene oxide polymers and their ethyl esters and acetyl derivatives in which the terminal hydroxyl groups have been modified are also suitable Synthetic oils of the dicarboxylic acid ester type including dibutyl adipate, di-Z-ethylhexyl sebacate, di-nhexyl fumaric polymer, di-lauryl azelate and the like may be used. Alkyl benzene types of synthetic oils such as tetradecyl benzene, etc., are also included. Liquid esters of acids of phosphorus including tricresyl phosphate, diethyl esters of decane phosphonic acid, and the like may also be employed. Also suitable are the polysiloxane oils of the type of polyalkyl-, polyaryl-, polyalkoxyand polyaryloxy siloxanes such as polymethyl siloxane, polymcthylphenyl siloxane and polymethoxyphenoxy siloxane and silicate ester oils such as tetraalkyland tetraaryl silicates of the tetra-Z-ethylhexyl silicate and tetra-p-tert.-butylphenyl silicate types. The process of the invention is particularly adapted to the preparationof stable dispersions in mineral lubricating oils and such oils are preferred accordingly. i The lubricating oil of the lubricant compositions prepared in accordance with the process of this invention may be employed in amounts of from about 100 to 100,000 times, on a weight basis, the amount of phthalic acid in the reaction mixture. This means that the final lubricant composition will contain from about 0.001 to about 1.0% by weight of phthalic acid based on the total composition. The ratio of phthalic acid in the reaction mixture to the lubricating oil is preferably such that the final lubricant composition contains from about 0.001 to about 0.5% by Weight of the phthalic acid. The present process is particularly suitable for producing stable dispersions of more than 0.15% by weight of phthalic acid in mineral lubricating oil whereas the usual direct methods of adding phthalic acid to lubricating oil do not give more than about 0.15% of acid in stable dispersion. In the production of lubricating oil concentrates for blending with oils of lubricating viscosity in the preparation of corrosion inhibited lubricant compositions, the phthalic acid reaction mixture may be combined with amounts of lubricating oil such that the concentrate contains up to 10% by weight or more of the phthalic acid. The most suitable concentrates, however, from the standpoint of stability and resistance to precipitation of the additive under storage conditions and the like are those containing from about 3 to 8% by weight of phthalic acid based on the total composition and the proportions of lubricating oil to phthalic acid are regulated accordingly.

The reaction mixture of phthalic acid and tertiary amine may be combined with the oil of lubricating viscosity by various means. Agitation of the two components is desirable to insure uniform distribution. This may be done by blowing with an inert gas such as nitrogen 'or stirring with mechanical stirrers. The operation may be carried out at ordinary temperatures, but slightly higher temperatures of from about to about F. may be advantageously employed to facilitate mixing of the "phthalic acid and tertiary amine reaction mixture with the lubricating oil.

The combined oil and reaction mixture are heated to liberate the tertiary amine. The temperature at which the tertiary amine salts of phthalic acid will decompose and permit the tertiary amine to be driven off is approxi mately the boiling point of the .tertiary amine. Preferably, this temperature should not exceed 600 F., the temperature at which the phthalic acids tend to sublime.

The tertiary amines produced by the decomposition of the tertiary amine salts and the excess tertiary amine in the reaction mixture are conveniently separated from the dispersion of phthalic acid in lubricating oil by simple distillation at temperatures equal to the boiling point of the tertiary amine. The tertiary amine thus separated may be recovered by condensation for further use.

Any excess phthalic acid which will not remain in stable dispersion in the oil of lubricating viscosity is separated from the stable dispersion of phthalic acid in oil by conventional methods for separating solids and liquids such as decantation, filtration and the like.

' The lubricating oil compositions and concentrates for preparing them derived by the process of this invention may also contain conventional lubricating oil additives which are known to the art. In a preferred embodiment of the invention the lubricating oils and concentrates therefor will contain lubricating oil detergents to aid the oil in carrying off insoluble decomposition products which are normally formed during ordinary service. 'These detergents are selected from the better known classes such as the metal salts of naphthenic acids, for example, aluminum naphthenate; metal salts of fatty acids and substituted fatty acids, for example, calcium stearate, calcium phenyl stearate, basic calcium phenyl stearate and calcium dichlorostearate; metal salts of aromatic acids and substituted aromatic acids, for example, calcium octyl salicylate; metal salts of petroleum sulfonic acids, for example, calcium sulfonate and basic calcium sulfonate; metal salts of alkyl phenol sulfides, for example, barium amyl phenol sulfide; metal salts of alkyl phenols, for example, aluminum dicetyl phenate and calcium dicetyl phenate; metal salts of thiophosphoric acid esters, for example, the zinc salt of the p-tert.amylphenyl ester of dithiophosphoric acid; and metal salts of wax substituted phenol derivatives, for example, the wax substituted metal phenatcs. Nonmetallic lubricating oil detergent additives which are also suitable include macromolecular copolymers characterized by oil solubilizing .monomer groups and polar type monomer groups such as the copolymers of methacrylic acid and lauryl methacrylate. Dispersants, as illustrated by the phosphatides such as animal lecithin and the partial or complete esters of long chain carboxylic acids with polyhydric alcohols such as pentaerythritol mono-oleate and glycerol sorbitan laurate may also be present. Still other additives such as pour depressants, viscosity index 'iriiprover's, wear inhibitors and the like which are commonly employed in lubricant compositions can be included when desired.

The above additives may be present in amounts up to 20% by weight of the final lubricant composition. In the preparation of concentrates, amounts up to 50% by weight or more may be employed. For present purposes, however, very superior lubricant compositions are provided by the present process when the additive is eniployed in amounts of from 0.1 to by Weight of the composition.

In a preferred embodiment of the process according to the present invention .stable'dispersions of more than 0.15% by weight of terephthalic acid are prepared in a mineral lubricating oil containing calcium petroleum sulfonate which oil analyzes at least 0.20 percent by weight calcium. The process is particularly adaptable to the preparation of stable dispersions in the form of lubricating oil concentrates of more than 0.25 percent by weight of terephthalic acid in a mineral lubricating oil analyzing at least about 4.0 percent by weight calcium attributable to calcium petroleum sulfonate.

The following examples are oifered in further illustration of the invention and show simplified procedures for producing lubricating oil compositions and concentrates therefor containing substantially greater amounts of phthalic acid than possible by means employed heretofore. Unless otherwise specified, the proportions are on a weight basis.

Example I In this example, the preparation of a stable dispersion of terephthalic acid in mineral oil containing a conventional lubricating oil detergent and an oil stabilizing agent is illustrated, both for the production of lubricating oil concentrates and lubricating oil compositions for internal combustion engines.

400 gm. of a lubricating oil detergent concentrate of calcium petroleum sulfonate and a solvent refined mineral lubricating oil base analyzing 1.71% by weight calcium and 308 gm. of a concentrate of a sulfurized calcium alkyl phenate sludge inhibitor or stabilizer in a solvent refined mineral lubricating oil base analyzing 4.43% by weight calcium are charged to a reaction vessel equipped with stirrer, thermometer, addition funnel, distillation column and heating means. 500 ml. of benzene is then added. The mixture is stirred at 150 F. for about 20 minutes.

In a separate vessel, 42.7 gm. of terephthalic acid is dissolved in 1000 ml. of pyridine with stirring at room temperature. The resulting reaction mixture of pyridine terephthalate dissolved in pyridine is then combined in the reaction vessel with the mineral lubricating oil concentrate of detergent and stabilizing agent mentioned above. Benzene and pyridine are continuously distilled off under a reduced pressure equal to about 20 mm. mercury, while the terephthalic acid and reaction mixture is-being added. Benzene is occasionally added to dilute the mixture until a total volume of 500 ml. is used.

The combined mineral lubricating oil concentrate and terephthalic acid pyridine reaction mixture are heated to about 250 F. This decomposes the pyridine terephthalate to liberate the pyridine. The pyridine and residual benzene are separated by stripping the contents of the reaction vessel to 350 F. at 2 mm. mercury pressure.

The mineral lubricating oil concentrate obtained by the procedure outlined above analyzes 2.75% by weight calcium in the form of calcium petroleum sulfonate and ,20 1nm./kg. sulfurized calcium cetyl phenate and 0.25%

by weight terephthalic acid. In a standard L4 engine test this lubricant composition gave a bearing weight loss of only 57 mg. and an engine cleanliness of 9.8 compared to a bearing weight loss of more than 500 mg. and

a cleanliness of 3.5 obtained with a similar lubricant composition containing no terephthalic acid.

Example 11 In this example, there is employed the same general method as the preceding example illustrating the process of the present invention. The base oil is another variety of compounded mineral lubricating oil for internal combustion engines.

The reaction flask is charged with 277 gm. of a calcium petroleum sulfonate concentrate in a solvent refined mineral lubricating oil base which analyzes 4.19% by weight calcium. 17.5 gm. of terephthalic acid in 1000 m1. of pyridine is then added. The mixture is heated and stirred as above. The pyridine is distilled off by heating to 350 F. at 2 mm. mercury pressure.

The concentrate contains 6.2% by weight terephthalic acid in completely stable form as evidenced by its bright, clear appearance. It remains stable on standing for several days at room temperature without noticeable formation of haze or precipitates.

4.075% by weight of the concentrate in a 60 VI solvent refined SAE 40 mineral lubricating oil base gives a superior lubricant composition containing 40 mm./kg. calcium petroleum sulfonate and 0.25% by Weight terephthalic acid. Such a composition is. capable of outstanding performance in internal combustion engines,

both from a standpoint of detergency and corrosion inhibition, as shown by its performance in tests described in the previously mentioned patent applications on phthalic acid corrosion inhibited lubricating oils.

Additional examples of preparations of stable dispersions of terephthalic acid in mineral lubricating oil in accordance with the process of this invention were carried out using the procedure of the foregoing examples. The mineral lubricating oil was a solvent-refined SAE 30 oil and the sulfonate, as indicated by the percent by weight calcium, was a calcium petroleum sulfonate. The data from these examples are given in the following table.

The outstanding advantages of the novel process of this invention in producing superior lubricant compositions and concentrates therefor is plainly evident from the above examples. By previous methods of adding terephthalic acid to lubricating oil compositions, it is not possible ordinarily to incorporate more than about 0.15 to 0.25% by weight of terephthalic acid if stable dispersions are to be obtained. By way of contrast, the process of the present invention permits the incorporation of terephthalic acid in amounts of more than 0.15% ranging up to 5.7% by weight or more, as shown by the above examples, to give remarkably stable dispersions.

As an additional example providing a more graphic illustration of the process of the present invention, attention is invited to the accompanying drawing which shows a simplified flow diagram of still another embodiment of the invention.

Referring to the drawing, a tertiary amine of the type described above is introduced via line 11 to reaction vessel 12. The phthalic acid of the aforementioned type is added to the reaction vessel through conveyor 13. .A stoichiometric excess of tertiary amine is preferably employed. The reactionvessel is equipped with mechanical TABLE Sulfonate, Terephthalic Mole Ratio of Appearance of Fin- Percent bv Acid, Tertiary ished Oil Containing Example N o. Tertiary Amine Wt. Cal- Percent by Amine to Terephthalic Acid i cium in Wt. in Oil Tcrephthalic After Standing Acid One Week Pyridine 0. 42 1. 0 100:1 No Precipitate.

do 0. 21 0. 25 400:1 D0. Triethylamine 0. 84 0. 2 300:1 Do. do 0.42 0.2 300:]. Do. do 0. 21 0.2 300:1 D0. Pimline O. 84 O. 2 420:1 Do. do 0. 21 0.2 420:1 D0. Triethanolamine 0. 84 0. 2 345:1 Do. rlo 0.21 0.2 345:]. D0.

N 0.42 0.1 White Precipitate.

do 0. 42 0.05 D0.

stirrer 14 and heating coils 16 as means for facilitating reaction of the tertiary amine and phthalic acid and solution of the resulting tertiary amine salt of phthalic acid in the excess tertiary amine. Any volatilizcd tertiary amine occurring during the preparation of the tertiary amine and phthalic acid reaction mixture is vented through line 17.

The reaction mixture of tertiary amine and phthalic acid is withdrawn via line 18 to disperser 19 which is provided with stirrer 21 and heating coils 22. Lubricating oil, which may contain other conventional lubricating oil additives, is added to the disperser via line 23. If desired for convenient handling, a solvent may be introduced through line 24. The lubricating oil and tertiary aminephthalic acid reaction mixture are combined with stirring and heating to give a dispersion of the tertiary aminephthalic acid reaction mixture in lubricating oil. Volatilized solvent and tertiary amine occurring at this stage of the operation are vented through line 26.

The combined oil and tertiary amine-phthalic acid reaction mixture are removed from disperser 19 and carried through line 27 to heater 28. Here the oil and reaction mixture are heated to decompose the tertiary amine salt of the phthalic acid and liberate the tertiary amine. During the decomposition, the mixture of oil, phthalic acid and tertiary amine are agitated by stirring means 29.

From heater 28, the tertiary amine and dispersion of phthalic acid in oil are conveyed via line 31 to separator 32 equipped with heating means 33. The tertiary amine and the dispersion of phthalic acid in oil are separated by distilling off the tertiary amine via line 34.

The dispersion of phthalic acid in oil is withdrawn from separator 32 via line 36 throughcooler 37 and line 38 to settler 39. In settler 39 any phthalic acid not held in stable dispersion is settled out and withdrawn via line 41. The final product, which is a stable composition of phthalic acid and oil of lubricating viscosity, is withdrawn from settler 39 via line 42.

In a cyclic process, the undispersed phthalic acid from settler 39 is returned via conveyor 41 to conveyor 13 and where it is introduced again to the process described above. Tertiary amine vapors from reactor 12 and disperser 19 are conveyed via lines 17 and 26, respectively, to line 34,

where they are combined with the solvent and tertiary amine from separator 32. The tertiary amine and solvent are conveyed via line 34 to fractionator 43 where they are separated by conventional means, as for example, by fractional distillation. From fractionator 43 the tertiary amine fraction is returned via line 44 to line 11 where 'it is introduced again to the process, as outlined above.

The solvent fraction is returned to the process in the same fashion via lines 46 and 24. 4

In the above descriptions of the superior new process in accordance with this invention it will be noted that the invention also includes a remarkably effective new corrosion inhibited lubricant composition which contains the effective corrosion inhibitor, phthalic acid, in unusually large amounts of above 1.0% by weight or more and preferably by weight or more based on the total composition. These unusually large amounts of phthalic acid corrosion inhibitor, particularly isophthalic acid and terephthalic acid, provide unusually outstanding lubricant compositions, since the eifective ingredient is present in amounts suflicient to inhibit corrosion throughout prolonged periods of service. The novel lubricating oil additive concentrates prepared by the method of the invention which contain 10% by weight or more of the phthalic acid possess similar unusual advantages over previously known compositions. It would appear that none of these superior new compositions were capable of existing prior to the present process.

This application is a continuation-in-part of Warren Lowe patent application, Serial No. 506,449, filed May 6, 1955, and now abandoned.

I claim:

1. A process for producing stable dispersions of more than 0.15% by weight of terephthalic acid in a mineral lubricating oil which comprises reacting terephthalic acid with a tertiary amine selected from the group consisting of tertiary hydrocarbon amines and tertiary hydroxy alkyl amines containing a total of from 5 to 15 carbon atoms in proportions of at least 20 moles of tertiary amine per mole of terephthalic acid, combining the reaction mixture thus obtained with the mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes at least about 0.2% by weight calcium, heating the combined oil and reaction mixture to liberate the tertiary amine and separating the tertiary amine and the resulting dispersion of terephthalic acid in mineral lubricating oil.

2. A process for producing stable dispersions of more than 0.15% by weight of terephthalic acid in a mineral lubricating oil which comprises reacting terephthalic acid with a tertiary hydrocarbon amine containing a total of from 5 to 15 carbon atoms in proportions of at least 20 'moles of tertiary amine per mole of terephthalic acid, combining the reaction mixture thus obtained with the mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes at least about 0.2% by weight calcium, heating the combined oil and reaction mixture to liberate the tertiary amine and separating the tertiary amine and the resulting dispersion of terephthalic acid in mineral lubricating oil.

3 A process for producing stable dispersions of more than 0.15% by Weight of terephthalic acid in a mineral lubricating oil which comprises reacting terephthalic acid with pyridine in proportions of at least 20 moles of pyridine per mole of terephthalic acid, combining the reaction mixture thus obtained with the mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes at least about 0.2% by weight calcium, heating the combined oil and reaction mixture to liberate the pyridine and separating the pyridine and the resulting dispersion of terephthalic acid in mineral lubricating oil.

4. A process for producing stable dispersions of more than 0.25% of terephthalic acids in a mineral lubricatin; oil which comprises reacting terephthalic acid with pyridine in proportions of at least 2() mols of pyridine per mol of terephthalic acid, combining the reaction mix ture thus obtained with a mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes at least 4.19 percent by weight calcium, heating the combined oil and reaction mixture to liberate the pyridine and separating the pyridine and the resulting dispersion of terephthalic acid in mineral lubricating oil.

5. A process for producing stable dispersions of more than 0.25% of terephthalic acids in a mineral lubricating oil which comprises reacting terephthalic acid with pyridine in proportions of at least 20 mols of pyridine per mol of terephthalic acid, combining the reaction mixture thus obtained with a hydrocarbon solvent and a mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes at least 4.19 percent by weight calcium, heating the combined solvent, oil and reaction mixture to liberate the pyridine and separating the pyridine and the resulting dispersion of terephthalic acid in mineral lubricating oil.

6. A process for producing stable dispersions of more than 0.25% of terephthalic acids in a mineral lubricating oil which comprises reacting terephthalic acid with pyridine in proportions of at least 20 mols of pyridine per mol of terephthalic acid combining the reaction mixture thus obtained with benzene and a mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes 4.19 percent by weight calcium, heating the combined benzene, oil and reaction mixtureto liberate the pyridine and separating the pyridine and the resulting dispersion of terephthalic acid in mineral lubricating oil.

7. A process for producing stable dispersions of more than 0.25% of terephthalic acids in a mineral lubricating oil which comprises reacting terephthalic acid with pyridine in proportions of at least 20 mols of pyridine per mol of terephthalic acid combining the reaction mixture thus obtained with benzene and a mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes 4.19 percent by weight calcium, heating the combined benzene, oil and reaction mixture to liberate the pyridine, separating the pyridine and the resulting dispersion of terephthalic acid in mineral lubricating oil and combining said dispersion with mineral lubricating oil to give a lubricant composition containing 40 mm./kg. calcium sulfonate and 0.25 percent by weight terephthalic acid.

8. A process for producing stable dispersions of more than 0.15 by weight of terephthalic acid in a mineral lubricating oil which comprises reacting terephthalic acid with triethylamine in proportions of at least 20 moles of triethylamine per mole of terephthalic acid, combining the reaction mixture thus obtained with the mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes at least about 0.2% by weight calcium, heating the combined oil and reaction mixture to liberate the triethylamine and separating the triethylamine and the resulting dispersion of telephthalic acid in mineral lubricating oil.

9. A process for producing stable dispersions of more than 0.15% by weight of terephthalic acid in a mineral lubricating oil which comprises reacting terephthalic acid with picoline in proportions of at least 20 moles of picoline per mole of terephthalic acid, combining the reaction mixture thus obtained with the mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes at least about 0.2% by weight calcium, heata ing the combined oil and reaction mixture to liberate the picoline and separating the picoline and the resulting dispersion of terephthalic acid in mineral lubricating oil.

10. A process for producing stable dispersions of more than 0.15% by weight of terephthalic acid in a mineral lubricating oil which comprises reacting terephthalic acid with triethanolamine in proportions of at least 20 moles of triethanolamine per mole of terephthalic acid, combining the reaction mixture thus obtained with the mineral lubricating oil containing calcium petroleum sulfonate, which oil analyzes at least about 0.2% by weight calcium, heating the combined oil and reaction mixture to liberate the triethanolamine and separating the triethanolamine and the resulting dispersion of terephthalic acid in mineral lubricating oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,134,736 Reuter Nov. 1, 1938 2,158,096 Werutz May 16, 1939 2,280,474 Byrkit Apr. 21, 1942 2,329,474 Lazar et al. Sept. 14, 1943

Claims

1. A PROCESS FOR PRODUCING STABLE DISPERSIONS OF MORE THAN 0.15% BY WEIGHT OF TEREPHTALIC ACID IN A MINERAL LUBRICATING OIL WHICH COMPRISES REACTING TEREPHTALIC ACID WITH A TERTIARY AMINE SELECTED FROM THE GROUP CONSISTING OF TERTIARY HYDROCARBON AMINES AND TERTIARY HYDROXY ALKYL AMINES CONTAINING A TOTAL OF FROM 5 TO 15 CARBON ATOMS IN PROPORTIONS OF AT LEAST 20 MOLES OF TERTIARY AMINE PER MOLE OF TEREPHTALIC ACID, COMBINING THE REACTION MIXTURE THUS OBTAINED WITH THE MINERAL LUBRICATING OIL CONTAINING CALCIUM PETROLEUM SULFONATE, WHICH OIL ANALYZES AT LEAST ABOUT 0.2% BY WEIGHT CALCIUM, HEATING THE COMBINED OIL AND REACTION MIXTURE TO LIBERATE THE TERTIARY AMINE AND SEPARATING THE TERTIARY AMINE AND THE RESULTING DISPERSION OF TEREPHTALIC ACID IN MINERAL LUBRICATING OIL.