US3896038A - Lubricating oil containing a polyamide pour point depressant - Google Patents

Abstract

A lubricating oil composition having improved pour point and dispersancy characteristics comprises a major amount of a lubricating oil and a small amount of a polyamide of a mixture of secondary and tertiary monocarboxylic acids having 19 to 31 carbon atoms in the molecule and a polyalkylene polyamine containing about 2 to about 6 alkylene units, there being from 2 to 4 carbon atoms in each alkylene group, said polyamide containing about 1 to about 3 amine groups in addition to amide groups.

Description

United States Patent Hartle 1 LUBRICATING OIL CONTAINING A POLYAMIDE POUR POINT DEPRESSANT [75] Inventor: Robert J. Hartle, Gibsonia, Pa.

[73] Assignee: Gulf Research 8: Development Company, Pittsburgh, Pa.

[22] Filed: June 5, 1973 [21] App1.No.: 367,179

[ July 22, 1975 3,405,064 10/1968 Mi11er 44/58 X 1448.048 6/1969 Le Sucr ct a1. 252/515 A 3.483.125 12/1969 Clough 7. 252/515 A Primary ExaminerDelbert E. Gantz Assistant Examiner-Andrew H. Metz [571 ABSTRACT A lubricating oil composition having improved pour point and dispcrsancy characteristics comprises a major amount of a lubricating oil and a small amount of a polyamide of a mixture of secondary and tertiary monocarboxylic acids having 19 to 31 carbon atoms in the mo1ecu1e and a polyalkylene polyamine containing about 2 to about 6 alkylene units, there being from 2 to 4 carbon atoms in each alkylene group. said polyamide containing about 1 to about 3 amine groups in addition to amide groups.

11 Claims, N0 Drawings LUBRICATING OIL CONTAINING A POLYAMIDE POUR POINT DEPRESSANT This invention relates to a novel lubricating oil composition and more particularly to a lubricating composition having improved pour point, dispersancy and detergency characteristics.

Lubricants for many present-day internal combustion engines are required not only to lubricate and to cool engine parts, but also to maintain the engine parts contacted by the lubricant in clean condition. Uncompounded lubricating oils are frequently found to be less than fully satisfactory with respect to the last mentioned function, especially under severe operating conditions, in that they permit the buildup of carbonaceous deposits that result not only from deterioration of the oil itself but also from engine fuel blow-by" contamination. These deposits interfere with proper engine functioning.

In order to improve the ability of oils to maintain an engine in clean condition. a wide variety of metalorganic compounds (principally alkaline earth metal salts), such as the calcium, barium, strontium and zinc salts of substituted phenols and petroleum sulfonic acids, salicylates and thiophosphoric acids have been proposed as detergents and dispersants. Although these metallic salt detergents and/or dispersants have been very useful in maintaining sludge and varnish suspended in the oil, they have the disadvantage of being themselves subject to breakdown and deterioration resulting in the formation of metallic ash which accumulates in the crankcase and, in some instances, in the combustion chamber of the engine.

In two-cycle engines, lubrication of the engine is accomplished by admixing the lubricating oil with the gasoline to form an oil-gasoline mixture which functions not only as a lubricant but also as a fuel for the engine. Inasmuch as the lubricating oil is admixed with the gasoline to form an oil-gasoline mixture which is consumed in the engine, the lubricating oil must be one which when burned in the engine does not adversely affect the operation of the engine. Thus, for example, the oil-gasoline mixture should give prolonged performance without giving rise to spark plug fouling, ring sticking, excessive combustion chamber deposits, piston or cylinder wall scuffing, scuffing or spalling of bearings, rusting or corrosion of engine parts, preignition and the like. Metallic detergents and/or dispersants in lubricating oil compositions for two-cycle engines are thus undesirable since such detergents and/or dispersants upon combustion form a metallic ash which acts as an abrasive and thus increases the wear of engine parts.

Many metallic detergents and/or dispersants have a further disadvantage in that they lack sufficient basicity to effectively counteract the deleterious acidic materials which are formed in lubricating oils upon prolonged use under oxidizing conditions. Still further, the metallic detergents and/or dispersants do not as a general rule enhance the pour point characteristics of the lubricating oil to which they are added. The pour point" of an oil is defined as the lowest temperature at which an oil will pour or flow when chilled without disturbance under specified conditions.

Various pour point depressors have been described in the literature. It is already known that certain unsaturated esters, for example, acrylate and methacrylate esters of higher aliphatic alcohols, can be polymerized to make high molecular weight products which are soluble in lubricating oils and are capable of reducing the pour point of such oils. It is also known that certain polyamides of mixtures of straightand branched-chain fatty acids and polyalkylene polyamides are capable of reducing the pour point of lubricating oils.

By way of illustration of prior art practices, U.S. Pats. Nos. 3,l l0,673 and 3,l69,980 to George J. Benoit, Jr. describe the preparation of polyamides of certain fatty acid mixtures and polyalkylene polyamines which are shown to be useful as pour point depressants and detergents in lubricants and fuels. The polyamides which are shown to be useful as pour point depressants are prepared from a critical mixture of straight-chain and branched-chain acids and polyalkylene polyamines. In these patents, it is taught that to impart improved pour point characteristics to a lubricant, the polyamide must be prepared from a polyalkylene polyamine and a fatty acid mixture, said fatty acid mixture containing from about 5 to about 30 mole percent of straight-chain fatty acids and from about to about mole percent of branched-chain fatty acids, said fatty acids containing from about 12 to about 30 carbon atoms each and said polyalkylene polyamine containing from 2 to 6 alkylene amine units each, there being from 2 to 4 carbon atoms in each alkylene group, said polyamide containing from I to 3 amine groups in addition to amide groups. Specific polyamides shown to be useful include the polyamide of mixtures of straightand methyl branched-chain C fatty acids and tetraethylenepentamine, said mixtures of fatty acids containing from about 5 to about 30 mole percent of stearic acid and from about 70 to about 95 mole percent of methyl branched-chain saturated fatty acid of 18 carbon atoms. These patents show that the polyamide of a straight-chain fatty acid, i.e., stearic acid and tetraethylenepentamine does not improve the pour point of the base oil but instead results in a composition having a pour point which is higher than the pour point of the base oil. These patents show further that the polyamide of a branched-chain C saturated fatty acid, i.e., a saturated 18 carbon atom fatty acid having methyl chain branching and tetraethylenepentamine, neither increases nor decreases the pour point of the base oil. Thus. these patents teach that a critical mixture of straightand methyl branched-chain C fatty acids must be used in producing the polyamide if the resulting polyamide is to be useful as a lubricating oil pour point depressant.

In accordance with the present invention, I have found that the pour point and dispersancy characteristics of a lubricating oil can be improved by incorporating in the oil a small amount of a polyamide of a mixture of secondary and tertiary monocarboxylic acids having from 19 to 3l carbon atoms, preferably from 19 to 25 carbon atoms in the molecule and a polyalkylene polyamine containing about 2 to about 6 alkylene units, there being from 2 to 4 carbon atoms in each alkylene group, said polyamide containing about I to about 3 amine groups in addition to amide groups.

The improved lubricating oil composition of my invention, therefore, comprises a major amount of a lubricating oil and a small amount, sufficient to improve the pour point and dispersancy characteristics of the lubricating oil, of a polyamide of a mixture of secondary and tertiary monocarboxylic acids having 19 to 31 carbon atoms, preferably 19 to 25 carbon atoms in the 3 molecule and a polyalkylene polyamine containing about 2 to about 6 alkylene units, there being from 2 to 4 carbon atoms in each alkylene group, said polyamide containing about I to about 3 amine groups in addition to amide groups.

The present invention is based on the surprising discovery that lubricating oils containing polyamides derived from a polyalkylene polyamine and a mixture of secondary and tertiary monocarboxylic acids having [9 to 3 l carbon atoms in the molecule having unexpected superior properties over lubricating oils containing polyamides derived from a polyalkylene polyamine and a branched-chain saturated fatty acid having l8 carbon atoms in the molecule. For example, lubricating oils containing the polyamides derived from tetrae thylenepentamine and a mixture of secondary and tertiary monocarboxylic acids having 19 to 31 carbon atoms in the molecule not only have improved pour point. detergency and/or dispersancy properties but also have improved thermal and oxidative stability over lubricating oils containing the polyamide derived from tetraethylenepentamine and a branched-chain monocarboxylic acid having 18 carbon atoms in the molecule, e.g., isostearic acid.

The base oil employed in the lubricating oil composition of the invention is an oil of lubricating viscosity and can be a mineral oil or a synthetic oil. Synthetic oils which can be used are synthetic oils of lubricating viscosity including, for example, polyalkylene ethers, sili' cones, esters of phosphoric and silicic acids, highly fluorinated hydrocarbons, polyaryl ethers, aliphatic esters and the like. Mineral oils which can be used are advantageously highly refined paraffinic oils. By the term highly refined" I mean a petroleum lubricating oil which has been refined by one of the more drastic refining methods known in the art, for example, by conventional aluminum chloride refining or by solvent extraction adapted to remove all or substantially all of the unstable constituents of the oil. An aluminum chloride refined and/or a solvent extracted paraffinic base oil, such as Pennsylvania oil. provides an excellent base oil for a composition of the invention. However, drastically refined Mid-Continent and Gulf Coastal oils can be used. A mineral oil which has been treated with hy drogen, whether a hydrofinished or hydrotreated oil, can also be used alone or in admixture with other oils. The particular base oil which is used will depend to some extent upon the ultimate use of the lubricating oil composition.

In preparing a two-cycle engine lubricating composition having maximum lubricating characteristics, I preferably employ a blend of mineral oils as the lubricating base. A particularly effective lubricating oil base for use in two-cycle engine lubricants is a blend of oils consisting essentially of a major proportion of a paraffinic mineral oil distillate having a viscosity of about 400 to about 600 SUS at 100 F. (378C) and a minor proportion of a bright stock having a viscosity of about 2500 to about 4500 SUS at 100 F. (378 C.). The amounts of the paraffinic mineral oil distillate and the bright stock are adjusted so that the viscosity of the lubricating oil blend is about 650 to about 800 SUS at I F. (37.8 C.). In general, the blend comprises about 65 to about 85 percent by volume of the less viscous mineral oil distillate and about to about 35 percent by volume of the more viscous bright stock. Bright stock is obtained by dewaxing and clay treating the residue remaining after vacuum distilling a mineral oil. The amount of the lubricating oil base employed in accordance with the invention depends to some extent upon the ultimate use of the lubricating composition. In general, however, the lubricating oil base comprises about to about 99.9 percent by weight of the lubricating composition.

The mixture of secondary and tertiary monocarboxylic acids suitable for use in preparing the polyamides can be produced by the acid catalyzed carboxylation of an alpha olefin having l8 to 30 carbon atoms, preferably 18 to 24 carbon atoms in the molecule. These acids and a method by which they can be obtained are shown in application Ser. No. 367,l77, now US. Pat. No. 3,842,106, by Anatoli Onopchenko and Johann G. D. Schulz entitled COMPOSITION CONTAINING HIGHER FATTY ACIDS filed concurrently herewith. As described in said application Ser. No. 367,l77, now US. Pat. No. 3,842,106, the C to C alpha olefin, preferably a C to C alpha olefin is introduced into a reactor containing sulfuric acid under a carbon monoxide pressure. Water is added to the reaction mixture from which the desired mixture of carboxylic acids having one more carbon atom than the reactant olefin is recovered. The sulfuric acid which is utilized is substantially anhydrous, that is, from about 92 to about I00 percent, preferably 95 to about 98 percent. The molar ratio of sulfuric acid to olefin is from about 3:1 to about 20: l preferably from about Szl to about 10: l. The pressure can be in the range of about I00 to about 5000 pounds per square inch gauge (about 7 to about 352 kilograms per square centimeter), preferably in the range of about 500 to about 2000 pounds per square inch gauge (about 35.2 to about 140.8 kilograms per square centimeter), the temperature in the range of about -l5 C. to about 100 C.. preferably about 0 C. to about 40 C., and the reaction time about 0.01 to about 12 hours, preferably in the range of about 0.l to about 4 hours. The reaction mixture, after depressuring, is added to water and the mixture of carboxylic acids formed as a result thereof floats on the surface thereof. The mixture of acids can then be recovered by decantation. About half of the carboxylic acids obtained are secondary and about half are tertiary. The secondary and tertiary monocarboxylic acids thus obtained can be defined as falling within the following two general structures:

Secondary (Iso) Carboxylic Acids (CH l 2 wherein x is the number of carbon atoms in the reactant olefin, that is, from 18 to 30 carbon atoms, preferably from about 18 to 24, and n is the integer 2, 3, 4 up to x/2 for even integers between l8 and 30 and 2, 3, 4 up to (.x+l )/2 for odd integers between 18 and 30, and

Tertiary (Neo) Carboxylic Acids wherein .r is as defined above. and n is the integer 2. 3. 4 up to .r/2 for even integers between 18 and 30 and 2. 3, 4 up to (x+l )/2 for odd integers between 18 and 30.

The preparation of the mixed secondary and tertiary monocarboxylic acids useful in the preparation of the polyamides is illustrated by the following specific examples.

EXAMPLE 1 (Secondary and Tertiary C Monocarboxylic Acids) Into a l-liter. 316 stainless steel. magnetically-stirred autoclave containing 444 grams of 97 percent aqueous sulfuric acid and under a carbon monoxide pressure of 1350 pounds per square inch gauge (95.1 kilograms per square centimeter), there was introduced, with stirring, 224 grams of l-octadecene. The reaction was allowed to proceed for a period of 4.3 hours at a temperature of about 24 C. At the end of the reaction period the crude mixture in the autoclave was depressured into a vessel containing about I200 grams of wet ice and the organic layer that formed on standing was separated in a separatory funnel and washed several times with approximately an equal volume of a hot percent aqueous solution of sodium chloride until the final washings were neutral to litmus paper. On work-up by distillation there was obtained 199.2 grams (78 percent efficiency) of a fraction possessing the following physical properties:

Neutral equivalent 3l2 (Theoretical 299) Specific gravity. l5.5 C. 0.8820 Viscosity. Centistokes. 98.9 C. 7.09 1 35 C. 3.44 l48 C. 2.77 Titer test. C. 1.2 Boiling point. C. 200-205 at about 1.5 mm Hg Refractive index. 27.5 C. IASlZ covered fraction: 2-nonadecanoic acid. 3- nonadecanoic acid. 4-nonadecanoic acid. 5- nonadecanoic acid. 6-nonadecanoic acid, 7- nonadecanoic acid. S-nonadecanoic acid. 9-

nonadecanoic acid. 2-methyl-2-octadecanoic acid. 3- methyl-3-octadecanoic acid. 4-methyl-4-octadecanoic acid. S-methyl-S-octadecanoic acid. 6methyl-6- octadecanoic acid. 7-methyl-7-octadecanoic acid. 8-

lit

methyl-S-octadecanoic acid and 9-methyl-9- octadecanoic acid.

EXAMPLE I] (Secondary and Tertiary C Monocarboxylic Acids) About 252 grams of l-eicosene and 576 grams of 97 percent aqueous sulfuric acid were reacted as in Example l for a period of 6 hours at a temperature of 30 C. and an initial carbon monoxide pressure of about 1000 pounds per square inch gauge (70.5 kilograms per square centimeter). On work-up by distillation there was obtained 248 grams (89 percent efficiency) of a liquid fraction possessing the following physical propertiesz Neutral equivalent 333 (theoretical 32b] Specific gravity, l5.5C. 0.8803 Boiling point. C. around 210 at [.2 mm Hg Refractive index. 275C. |.4528

heneicosanoic acid. 4-heneicosanoic acid. 5- heneicosanoic acid. 6-heneicosanoic acid. 7- heneicosanoic acid, S-heneicosanoic acid. 9-

heneicosanoic acid and l0-heneicosanoic acid.

EXAMPLE lll (Secondary and Tertiary Mixed C .,-C Monocarboxylic Acids) About 220 grams ofa normal C alpha olefin mixture and 445 grams of 97 percent aqueous sulfuric acid were reacted as in Example I for a period of 4 /2 hours at a temperature of 30 C. and an initial carbon monoxide pressure of about 1350 pounds per square inch gauge (95.1 kilograms per square centimeter). The alpha olefin feed had an average molecular weight of 295 and contained 3.3 weight percent of l-octadecene. 51 weight percent of l-eicosene. 37.9 weight percent of l-docosene and 7.8 weight percent of l-tetracosene. On work-up of product by distillation there was obtained 149 grams (71 weight percent efficiency) of a liquid fraction of C to C carboxylic acids possessing the following physical properties:

Neutral equivalent 356 Specific gravity, l5.5C. 0.8789 Viscosity. centistokes,

148C. 3.39 Titer test 0C. l2.9 Boiling point. "C. 220-230 at about Refractive index. 275C 1.4536 Iodine Number L4 The mixture obtained contains 76 isomers. l6 C carboxylic acids from the C olefin charge. 18 C carboxylic acids from the C olefin charge C carboxylic acids from the C olefin charge and 22 C carboxylic acids from the C olefin charge. with half of the isomers at an individual carbon number level being secondary and half being tertiary carboxylic acids.

The alpha olefins which are used in preparing the mixture of secondary and tertiary monocarboxylic acids for the purposes of this invention are available commercially so that neither the alpha olefins per se nor the method by which they are obtained constitutes any portion of the present invention. According to one method which is described in US. Pat. No. 2,699.45? which issued on Jan. 11, 1955, to Karl Ziegler and Hans-Georg Gellert. an alpha olefin is obtained by p0 lymerizing ethylene or a mixture of ethylene with other unsaturated hydrocarbons at a temperature of about 60 to about 250 C. in the presence of a metal polymerization activator comprising a metal selected from the group consisting of beryllium, aluminum, gallium and indium having the valence linkages thereof individually bound to members selected from the group consisting of hydrogen, monovalent saturated organic hydrocarbon radicals and monovalent aromatic organic hydrocarbon radicals.

The alpha olefins used in preparing the secondary and tertiary C C and mixed Cry-C25 monocarboxylic acids of Examples 1, I1 and Ill have the following typical characteristics.

e.g., Polyamine H, which comprises a mixture of cyclic, straightand branched-chain components are also acceptable reactants.

The polyalkylene polyamines are available commercially so that neither the polyalkylene polyamines per se nor their method of preparation constitutes any portion of the present invention. The polyalkylene polyamines, for example, can be prepared by reacting ammonia with an alkyl dihalide.

The polyamides suitable for use in preparing a lubrieating composition of the present invention can be prepared according to known methods. These polyamides and a method by which they can be obtained are shown in application Ser. No. 367,180 and now U.S. Pat. No. 3,864,368, by Robert .I. Hartle entitled A POLYAM- lDE OF A MIXTURE OF SECONDARY AND TER- TlARY MONOCARBOXYLIC ACIDS filed concurrently herewith. As described in said application Ser. No. 367.180 and now US. Pat. No. 3,864,368, the polyamides can be prepared by reacting the mixture of secondary and tertiary carboxylic acids and the polyalkylene polyamine at a temperature of about 250 to about 500 F. 121 to about 260 C.) until reaction is substantially complete. The reaction may require a pe riod of about 1 to about 24 hours. Inasmuch as water is formed in the reaction, completion of the reaction is aided by removal of the water substantially as fast as it is formed. Removal of the water is advantageously ef- Eicosenem) Ocladecene- 1 Octadecene-l to Tetracosene-l Mixture iil' u) Specific Gravity,

ASTM D1 298:

Open cup method The polyalkylene polyamines useful in preparing the polyamides for the purposes of this invention include those having the formula fected by heating the reaction mass at a reduced pressure, i.e., pressure less than atmospheric.

Formation of the polyamides is believed to involve at least a two-step reaction between the carboxylic acid mixture and the polyalkylene polyamine. The proportions of the carboxylic acid mixture and the polyalkylene polyamine may be such that the moles of carboxylic acid are equal to the molar equivalents of amine groups in the polyalkylene polyamine. However, it is preferred to employ from about 1 to about 3 moles less acid than the number of available amino groups in the polyamine. The product of the reaction is theoretically a polyamide which contains an average of three amido groups and two free amino groups per molecule. The acyl groups may be attached to any of the nitrogen atoms in a manner such that there is an overall statistical average of 3 acyl groups per polyamide molecule. The reaction between the carboxylic acid and the polyalkylene polyamine is believed to proceed in accor- 9 dance with the following representative equations, it being understood that the acyl groups may be attached to any of the nitrogen atoms to give an overall average of 3 acyl groups per polyamide molecule.

tetraethylenepentamine (26.33 amine equivalents). The amine is heated to 125 C. with stirring in a nitrogen atmosphere. The addition of a mixture of secondary and tertiary C monocarboxylic acids obtained by 5 the sulfuric acid catal zed carbox lation of a C alpha 3 RCOOH NH '(CH2CH2NHhH Amine Salt olefin as set forth in Example I is then started. A total of 5079 grams 16.28 equivalents of acid) is added in mine salt 4 a a slow stream over a period of 2.5 hours whilekeeping the temperature at l25l40 C. After addition of the RCONH (CH CH NHl CH CH NCH CH NHCOR 3H O l0 acid is complete, the reaction mixture is stirred at 150 C. for 1 hour. The temperature is then increased to 195 C. and held at this temperature for about 3 hours with rapid stirring while nitrogen is bubbled slowly The amount of the polyamide added to the lubricatthrough the mixture. At the end of the 3 hour period ing oil base in accordance with the present invention is about 50 percent of the total theoretical amount of that amount which is sufficient to improve the pour water is evolved. The nitrogen tube is then replaced by point and dispersancy characteristics of the lubricant. a fine capillary and water aspirator vacuum is applied The minimum and optimum effective proportions can to the system. Heating at 195 C. is continued at -30 vary somewhat depending upon the nature of the parmm Hg for 2.5 hours. Total water evolved at this time ticular polyamide and the ultimate use of the lubricat- 20 i b t 72% of theoretical. An oil-pump vacuum (5 ing composition. In general, the polyamide is incorpomm Hg) i then applied and heating is continued at rated in a lubricating oil base in an amount of about 0.1 [95 C. for about 7 hours. Total water Collected at the to about 15 percent by weight of the lubricating oil end of this seven hour period is 87 percent of theoreticomposition. Good pour point and dispersancy characcal. No evidence of further reaction is observed. The teristics have been obtained in lubricants containing Product 902 grams) sa leanthiekamber fluid havabout 1 to about 10 percent by weight of the polyaming the following analysis: ides of the C to C31 monocarboxylic acids and tetraethylenepentamine. I The polyamides described herein can be incorpo- 3 22 g ci z rated in a wide variety of lubricating oil bases, such as Niiro nfik B weigiu for example, lubricants for two-cycle outboard engines, 159 marine diesel engines, gasoline and diesel automotive Acid Number A51-M D664 engines, stationary internal combustion engines and the T0131 Base Number 105 like. Free Base, by titration to pH 3 2.03 meq/g Specific Gravlty. (AF/60F. The preparation of polyamides useful in the composi- (15.5/l5.5C.] 0.9226 tions of this invention is illustrated by the following specific examples. When the procedure of Example IV is repeated using a mixture of secondary and tertiary C monocarbox- EXAMPLE [V ylic acids from Example II and a mixture of secondary A 12 liter flask, equipped with stirrer, thermometer, and tertiary mixed C monocarboxylic acids from probe for temperature controller and recorder, nitro- Example lll, instead of a mixture of secondary and tergen inlet and take-off condenser, is flushed with dry nitiary C monocarboxylic acids, the polyamide product trogen and charged with 1107 grams of commercial analyses shown in Table l are obtained.

TABLE 1 Product Analysis Free Base Total Acid Molar Ratio Reaction Conditions Nitrogen, wt% meq/g No. Example No. Acid Reactant Acid/'I'IEPA Temp. 6C. Hours Total Basic (to pH3) ASTM D664 V Secondary and 3.28 205 7 5.46 3.15 1.74

Tertiary C2, monocarboxylic acids (Example II) VI Secondary and 3.23 9 4.80 2.72 1.48 55 Tertiary C -C monocarboxylic acids (Example I") VII Second and 2.00 195 [3 7.11 5.00 37 Tertiary .Cg

monocarboxylic acids (Example Ill] '"I'EPA tetraethylenepentamine "First two hours at atmospheric pressure. Remainder at 30 mm Hg or lower.

The herein described polyamides can be incorporated in the lubricating oil in any convenient way. Thus, the polyamide can be added directly to the lubricating oil by thoroughly blending the polyamide in the lubricating oil at the desired level of concentration. Alternatively. the polyamide can be blended with suitable solvents to form concentrates that can be readily dissolved in the appropriate lubricating oils at the desired concentrations. The concentrate should contain at least l percent by weight of the polyamide pour point depressant and preferably about 25 to about 65 percent by weight of the polyamide. The solvent in such a concentrate may be present in amounts of about 35 to about 90 percent by weight. The solvent preferably boils within the range of about 38 to about 37l C. depending upon the ultimate use of the lubricating oil composition. Suitable solvents which can be used for this purpose are naphtha, kerosene, benzene, xylene, toluene, hexane, light mineral oil. stoddard solvent and mixtures thereof. The particular solvent selected should, of course. be selected so as not to adversely affect the other desired properties of the ultimate lubricating oil composition, Thus, if the lubricating oil is to be used as a two-cycle engine lubricant, the solvent should preferably burn without leaving a residue and should be non corrosive with respect to metal. specifically ferrous metals.

in order to illustrate the improved pour point charac teristics of a lubricating oil when compounded in accordance with the present invention, pour points (ASTM D97) were obtained on a lubricating oil base with and without the addition of the polyamides of the mixed secondary and tertiary C to C monocarboxylic acids produced in the acid catalyzed carboxylation of the C to C alpha olefins and tetraethylenepentamine as described in Examples IV, V and Vi. The base oil used in illustrating the invention is a blend of 86 percent by volume of a hydrofinished lubricating oil (600 SUS at 100 F. [378 C.] and 68.7 SUS at 2l0 F. [989 C.]) and I4 percent by volume of a bright stock (2572 SUS at 100 F. [37.8 C.] and 155 SUS at 2l0 F. [98.9" C.]). The base oil has the following typical characteristics:

Grin ity. API 28.2 Viscosity, SUS

at lOU F, (37.3 CJ 700 at 2 HP F. (939 C.) 74.6 Flash point, P-M, Cr H83 Fire point, CC. C. 296.| Pour point. +5 F. (-l5C.J

The test results are shown in the following Table II.

TABLE 11 Lubricating Composition As shown by the test results summarized in Table II. the polyamides of the mixed secondary and tertiary C (Example lV), C21 (Example V) and mixed C to C (Example VI) monocarboxylic acids produced by the acid catalyzed carboxylation of the C to C alpha olefins (Examples I, II and Ill) and tetraethylenepentamine impart improved pour point characteristics to a lubricating oil base, although optimum improvement is obtained at different concentration levels with the vari ous polyamides. While a maximum pour point improvement with the polyamide prepared from the secondary and tertiary C monocarboxylic acids requires 9 percent by weight of polyamide, maximum pour point improvement with the polyamide prepared from the mixed secondary and tertiary C and the mixed secondary and tertiary C to C monocarboxylic acids can be obtained with as little as 1 percent by weight of the polyamide. Thus, in accordance with the present invention, for economic reasons, the polyamides prepared from the mixed secondary and tertiary C acids and the mixed secondary and tertiary C to C monocarboxylic acids are preferred.

As indicated hereinabove. the lubricating oil composition of the invention can be utilized as a two-cycle engine lubricating oil composition. To illustrate this use. a lubricating oil composition was prepared by blending 60.6 percent by volume ofa hydrofinished neutral min' eral oil (600 SUS at F. [378 C.[ and 68.7 SUS at 2l0 F. [98.9" C.]), l0.0 percent by volume of a bright stock (2572 SUS at [00 F. [378 C.[ and l55 SUS at2l0 F. [989 C.]), 20.0 percent by volume of stoddard solvent and 9.4 percent by volume of the polyamide reaction product of Example lV. One volume of the lubricating oil composition thus obtained was blended with 50 volumes of leaded regular grade gasolines. The fuels thus obtained were employed in l00 horsepower and 50-horsepower outboard engines. The test procedure employed in the outboard engines was conducted, except for a change in ratio of gasoline to lubricant, in accordance with the Outboard Boating Club (O.B.C.) Outboard Test Procedure. The test procedure which was used was altered from that established by the O.B.C. in that l employed a gasoline to lubricant volume ratio of 50:l instead of 20:] as recommended by the O.B.C. According to the O.B.C. procedure. the engine is operated for 100 hours of cyclic opcration, each cycle consisting of 55 minutes at full throttle and 5 minutes at an idling speed. During the 5- minute idle. there are 5 rapid accelerations to wide TABLE III Lubricating Composition, 7r by Volume Neutral mineral oil (600 SUS at 100 F. [37.8" C. 1; 68.7 SUS at 2l0 F, I985? C. 606 Bright stock (2572 SUS at 100 F.

[37.8" C.[; SUS at 2l0 F.

[989 (.l] l().() Stoddard solvent 20.0 Polyamide product of Example IV 94 Inspection (iravil 'API 3 l .3

TABLE Ill-Continued ll) 71.9 light to medium Piston or Cylinder Wall Scuffing nil Number of instances of Preignition nil nil Condition of Bearings. pitting nil nil Spark Plug Failures I nil As shown by the data in Table III, the lubricating composition of the invention gives excellent engine cleanliness ratings and freedom from preignition even when used with a leaded gasoline in a two-cycle engine. The ring wear and combustion chamber deposits are also satisfactory. In addition, there is no evidence of piston or cylinder wall scuffing and no evidence of connecting rod or piston pin needle bearing pitting.

As disclosed hereinabove, lubricating oils containing polyamides derived from tetraethylenepentamine and a mixture of secondary and tertiary monocarboxylic acids having 19 to carbon atoms in the molecule not only have improved pour point. detergency and/or dispersancy properties but also have improved thermal and oxidation stability over lubricating oils containing the polyamide derived from tetraethylenepentamine and a branched-chain monocarboxylic acid having 18 carbon atoms in the molecule. e.g.. isostearic acid. In order to illustrate the thermal-oxidation and deposition characteristics of compositions of the invention containing polyamides derived from a polyalkylene polyamine and mixed secondary and tertiary monocarboxylic acids having l9 to 25 carbon atoms in the molecule in comparison with a polyamide derived from the same polyalkylene polyamine and a branched-chain monocarboxylic acid having l8 carbon atoms in the molecule, e.g.. isostearic acid. lubricating compositions containing the products of Examples IV and VII were compared in the Alcor Deposition Test with a lubricating composition containing the isostcaric acid triamide of tetraethylenepentamine. The Alcor Deposition Test unit is designed for service evaluation of fluid lubricant thermal-oxidation degradation and deposition characteristics. The Alcor Deposition Test comprises continuously circulating aerated test fluid through a filter and through the annular space between an electrically heated tube and a concentric housing. The entire test unit is enclosed in an electrically heated cabinet. In conducting the test. 250 ml of test oil is circulated con tinuously by a constant speed pump from a cooler/- sump through the annular space between an electricaIly heated tube and concentric housing and back to the cooler/sump. Air saturated with water is injected into the circulating oil just before it enters the heater tube annulus. On leaving the heater tube annulus. the air/oil mixture returns to the cooler/sump; excess air is vented and oil temperature is kept constant by air cooling. Cooler/sump oil level is maintained by automatic feed from a makeup reservoir. The cooler/sump base houses a mesh oil filter. The test conditions can be varied so long as they are constant for a given series of tests. The oil temperature can be varied to about 370 C. but is usually maintained at about C. The heater tube temperature can be varied to about 535 C., but is usually maintained within the range of about 150 to about 3 l5 C. The air injection can be varied to i000 ml per minute. The oil flow rate is fixed at 300 ml per minute. The cabinet temperature can be varied to about 315 Cv but is usually maintained about 40 C. below the oil temperature. The duration of the test can be varied. but is usually 24 or 48 hours. At the conclusion of the test, the deposits in the tube are weighed. A deposit rating is obtained by summing the products of each per inch of heater tube rating times the corresponding per inch heater tube deposit weight. then dividing by 10. Filter deposits are determined by noting the increase in filter weight after the test. This measurement provides a measure of sludge and the tendency of particulate matter to flake off the heater tube during testing. The overall rating is determined by summing the tube deposits, the deposit rating and filter deposits and then dividing by 2. This provides a single reference point for assessment of overall deposit characteristics. An overall rating that is low indicates lubricant stability and resistance to thermal and oxidative degradation and deposit formation. Relatively small changes in neutralization number and viscosity of the lubricant during the test is another indication of resistance to degradation. The make-up of the lubricating compositions evaluated in the Alcor Deposition Test and the results of the evaluations are summarized in Table IV.

TABLE IV Test Conditions: Lower Tube Temp., C. 260 Oil-in Temp, C. 150 Cabinet Temp. C. 93.3 Air Flow cc/min 1,000 Test Duration, Hours 24 Lubricating Composition. By Volume A B C Neutral mineral oil (600 SUS at l0OF. [37.8"C.]; 68.7 SUS at 210F.

l98.9C.l) 78.3 78.3 78.3 Bright Stock (2572 SUS at 100F. [318C]; I55 SUS at 2l0F. [98.9C.|) 12.7 12.7 l2.7 Polyamide product of Example IV 9.0 Polyamide product of Example VII 9.0 Polyamide of isostearic acid and tetraethylenepentamine" 9.0

TABLE IV Continued Test Conditions: Lower Tube Temp., C. 260 Oil-in Temp, C. 150 Cabinet Temp, C. 93.3 Air Flow cc/min 1.000 Test Duration. Hours 24 Lubricating Composition. By Volume A B C BL S L'L Critical Temp. "C. 285 30l .7 304.4 Deposits Rating 37.3 17.6 26.0 Tu e Deposits. mg. 26.5 20.3 [5.0 Filter Deposits. mg. 47.2 36.3 i967 Oil Consumption. ml. 40 20 30 Overall Rating (0 is clean) 55 37 1004 Viscosity. SUS at 100F. (378C). lnitial BlZ 802 854 24 hours 982 954 [058 "/r Increase 20.) I89 23.9

Total Acid No, initial 53 3.0 0.57 24 hours 6.0 4.5 2.80 change +0.7 +1.5 +2.23

'lsostean'c acid triarnide of tetraethylenepentamine 7c Nitrogen (Total. 6.30; Basic, 2.34)

As shown by the data in Table IV. the lubricating I claim:

compositions of the invention (Compositions A and B) have good resistance to degradation and deposit formation in comparison with a composition not within the scope of the invention (Composition C). It will be noted that Compositions A and B had filter deposits of 47.2 mg and 36.3 mg, respectively whereas Composition C had filter deposits of l967 mg. Furthermore, the overall rating of Compositions A and B were 55 and 37, respectively. whereas the overall rating of Composition C was 1004 The percentage increase in viscosity after 24 hours was greater for Composition C than for either Composition A or Composition B. Likewise. the change in total acid number for Composition C was greater than the change in total acid number for either Composition A or Composition B. In summation, the data show that lubricating compositions which contain the poly-amides of mixed secondary and tertiary monocarboxylic acids having 19 to 25 carbon atoms per molecule and tetraethylenepentamine are surprisingly more resistant to thermal and oxidative degradation and deposit formation than a lubricating composition which contains the polyamide of a branched-chain monocarboxylic acid having l8 carbon atoms in the molecule (isostearic acid) and tetraethylenepentamine.

The lubricating composition of this invention can contain conventional lubricant additives, if desired, to improve other specific properties of the lubricant without departing from the scope of the invention. Thus. the lubricating composition can contain a corrosion and rust inhibitor. an extreme pressure agent, an antioxidant. an antifoamant, a metal deactivator, a viscosity index improver, a sludge inhibitor. a thickener, a dye and the like. Whether or not such additives are employed and the amounts thereof depend to a large extent upon the severity of the conditions to which the composition is subjected and upon the stability of the lubricating oil base in the first instance. When such conventional additives are employed they are generally added in amounts between about 0.01 and 5 percent by weight based on the Weight of the total composition.

While my invention has been described with reference to various specific examples and embodiments. it will be understood that the invention is not limited to such examples and embodiments and may be variously practiced within the scope of the claims hereinafter made.

l. A lubricating composition comprising a major amount of a lubricating oil and a small amount, sufficient to improve the pour point and detergencydispersancy characteristics of the lubricating oil. of a polyamide of a mixture of about equal amounts of secondary and tertiary monocarboxylic acids and a polyalkylene polyamine containing about 2 to about 6 alkylene units, there being from 2 to 4 carbon atoms in each alkylene group, said mixture of secondary and tertiary monocarboxylic acids falling within each of the following general structures Cil ii-C-COOl-l wherein x is a number from 18 to 30 and n is the integer 2, 3. 4 up to x/2 for even integers between 18 and 30 and 2, 3, 4 up to (.r-i-l )/2 for odd integers between 18 and 30. said polyamide containing about I to about 3 amine groups in addition to amide groups and being the product obtained by reacting said polyalkylene polyamine and said mixture of secondary and tertiary monocarboxylic acids at a temperature of about 250 F. (121 C.) to about 500 F. (260 C.) until the rear. tion is substantially complete. the proportion of said carboxylic acid mixture and the polyalkylene polyamine being such that there are from about i to about 3 moles less acid than the number of available amino groups in the polyamine.

2. A lubricating composition according to claim 1 wherein said polyamide comprises about Oil to about percent by weight of the lubricating oil composition.

3. A lubricating composition according to claim 1 wherein said polyalkylene polyamine is tetraethylenepentaminei 4. A lubricating composition according to claim 3 wherein x is a number from 18 to 24.

5. A lubricating composition according to claim 4 wherein said polyamide comprises about 1 to about it) percent by weight of the lubricating oil composition.

6. A lubricating composition according to claim 3 wherein x is 18.

7. A lubricating composition according to claim 6 wherein said polyamide comprises about 1 to about It) percent by weight of the lubricating oil composition.

8. A lubricating composition according to claim 3 wherein x is 20.

9. A lubricating composition according to claim 8 wherein said polyamide comprises about 1 to about 10 percent by weight of the lubricating oil composition.

10. A lubricating composition according to claim 3 wherein .r is a mixture of even numbers from 18 to 24.

11. A lubricating composition according to claim 10 wherein said polyamide comprises about 1 to about [0 percent by weight of the lubricating oil composition.

Claims (11)

1. A LUBRICATING COMPOSTION COMPRISING A MAJOR AMOUNT OF A LUBRICATING OIL AND A SMALL AMOUNT, SUFFICIENT TO IMPROVE THE POUR POINT AND DETERGENCY-DISPERSANCY CHARACTERISTICS OF THE LUBRICATING OIL, OF A POLYAMIDE OF A MIXTURE OF ABOUT EQUAL AMOUNTS OF SECOND ARY AND TERTIARY MONOCARBOXYLIC ACIDS AND A POLYALKYLENE POLYAMINE CONTAINING ABOUT 2 TO ABOUT 6 ALKYLENE UNITS, THERE BEING FROM 2 TO 4 CARBON ATOMS IN EACH ALKYLENE GROUP, SAID MIXTURE OF SECONDARY AND TERTIARY MONOCARBOXYLIX ACIDS FALLING WITHIN EACH OF THE FOLLOWING GENERAL STRUCTURES

2. A lubricating composition according to claim 1 wherein said polyamide comprises about 0.1 to about 15 percent by weight of the lubricating oil composition.

3. A lubricating composition according to claim 1 wherein said polyalkylene polyamine is tetraethylenepentamine.

4. A lubricating composition according to claim 3 wherein x is a number from 18 to 24.

5. A lubricating composition according to claim 4 wherein said polyamide comprises about 1 to about 10 percent by weight of the lubricating oil composition.

6. A lubricating composition according to claim 3 wherein x is 18.

7. A lubricating composition according to claim 6 wherein said polyamide comprises about 1 to about 10 percent by weight of the lubricating oil composition.

8. A lubricating composition according to claim 3 wherein x is 20.

9. A lubricating comPosition according to claim 8 wherein said polyamide comprises about 1 to about 10 percent by weight of the lubricating oil composition.

10. A lubricating composition according to claim 3 wherein x is a mixture of even numbers from 18 to 24.

11. A lubricating composition according to claim 10 wherein said polyamide comprises about 1 to about 10 percent by weight of the lubricating oil composition.