US3110673A

US3110673A - Lubricant composition

Info

Publication number: US3110673A
Application number: US99706A
Authority: US
Inventors: Jr George J Benoit
Original assignee: California Research LLC
Current assignee: California Research LLC
Priority date: 1961-03-31
Filing date: 1961-03-31
Publication date: 1963-11-12
Anticipated expiration: 1980-11-12

Description

3,110,673 LUBRICANT COMPGSITIQN George J. Benoit, in, San Anselmo, Calif., assign'or to Caiifornia Research Corporation, San Francisco, Calif,

a corporation of Delaware No Drawing. Filed Mar. 31, 1961, Ser. No. 99,706 6 Claims. (Cl. 252F515) This invention is directed to a novel lubricant composition. More particularly the invention is concerned with a superior new lubricant composition containing a pour point depressant ashless detergent for use in internal combustion engines.

Detergents are commonly added to lubricant compositions to prevent the deposit of solid materials on engine surfaces which come into contact with the lubricant compositions. The deposits interfere with proper circulation of the lubricant composition in the engine and also act as abrasives which aggravate the Wearing of engine parts.

Many detergents presently employed in lubricant compositions are found to contribute a substantial proportion of the deposits in modern engines. This is due to the fact that the detergents are commonly employed as metal salts and such metal salts form an ash deposit when the lubricant composition is consumed in the engine.

Lubricant compositions also contain pour point depressants to modify the flowing properties of the base oil so as to lower its pour point. The temperature at which a lubricant composition ceases to flow or pour is called its pour point and it is important that lubricant compositions be capable of flowing freely through oil lines and between moving engine parts at low temperatures in order to insure proper functioning of the lubricant composition in the engine.

In accordance with the present invention there is provided a superior new ashless detergent lubricant composition having pour point depressing properties in the lubricant composition comprising a major portion of an oil of lubricating viscosity and a minor portion sufficient to lower the pour point and enhance the detergent characteristics of the composition of polyamide of fatty acids and polyalkylene polyamine in which the fatty acids are mixtures of from about 5 to about 30 mole percent of straight-chain fatty acids and from about 70 to about 95 mole percent of branched-chain fatty acids, said fatty acids containing from about 12 to about 30 carbon atoms each and said polyalkylene polyamines containing from 2 to 6 alkylene amine units each, there being from 2 to 4 carbon atoms in each alkylene group, said polyamide containing frdm l to 3 amine groups in addition to amide groups.

IThe lubricant composition of this invention as described above is unusually effective in depressing the pour point of the base oil of lubricating viscosity. The characteristically mixed fatty acid groups of the polyamides provide pour points which are surprisingly lower than similar oils containing polyamides characterized by either of the fatty acid groups alone. I

In adition to the pour depressing properties as mentioned above, the lubricant composition of the invention acts to prevent engine deposits. Since there is no metal component in the additive it is also substantially free of ash-formingtendencies.

Thus is accordance with the present invention a single additive is found to give both outstanding pour depressing and detergent properties in combination. This eliminates the necessity for multiple use of dilferent additives which present problems of compatibility and tend to have an adverse effect on one another.

Detergent lubricating oil compositions containing the pour depressant ashless detergent in accordance with 3,110,673 Patented Nov. 12, 1963 the present invention are particularly satisfactory for use in 2-eycle gasoline engines. Such engines are becoming increasingly common in recent years and are found in chain saws, lawn mowers, outboard marine engines and small cars or motor scooters.

The polyamides of the present invention may be conveniently illustrated by the following structural formula:

in which the alkylene group R contains from 2 to 4 carbon atoms, the radical R is hydrogen or an acyl group Ra( iwhich is derived from a mixture of from about 5 to about 30 molepercent of straight-chain fatty acid and from about 70 to about 95 mole percent of branched-chain fatty acid, said fatty acids containing from about 12 to about 30 carbon atoms and n is an integer of from 1 to 5.

The polyamide of this invention is conveniently prepared according to known methods by reacting the polyamine and the mixed fatty acids at conventional temperatures for the usual period of time required to amidify the amino groups of the polyalkylene polyamine. For present purposes temperatures in the range from about 250 F. to about 500 F. are suitable. Usually the amiclification reaction requires from about 2 to 10 hours. Means for removing water of condensation is employed and reduced pressures are desirable to effect amidification at the lower reaction temperatures.

The proportions of fatty acids mixture and polyalkylene polyamine may be such that the moles of the fatty acids are equal to the molar equivalents of amine groups in the polyalkylene polyamine. As already mentioned it is preferred that moles of fatty acid be on the average of from about 1 to about 3 moles less than the number of available amino groups in the polyamine.

The polyamide of the present invention which is formed by the reaction of fatty acid and polyalkylene polyamine is illustrated in the above structural formula as being in the nature of linear pol-yamide. Such linear polyamides undergo further condensation upon continued heating at higher temperatures with terminal amino groups to give either the monoor bis-imidazoline ring structure as illustrated by the following formula:

Suitable fatty acids for the preparation of the polyarnides of the present invention contain from- 12 to 30 carbon atoms as mentioned above and preferably from 16 to 20 carbon atoms. illustrative straight-chain acids include lauric acid, myristic acid, palmitic acid, stearic acid, eicosanoic acid, triacontanoic acid, etc.

Suitable branched-chain fatty acidsare those derived by synthesis such as oxidation of olefins and polyolefins. Acidsderived from the OX0 process are also suitable. Another source is polymerization of unsaturated acids followed by hydrogenation. For example, an unsaturated acid such as linoleic acid is dirnerized in accordance with typical polymerization techniques. 'During the reaction, part of the acid product is broken down to give an unsaturated mono acid lay-product having methyl chain branching. This product is hydrogenated resulting in a branched-chain saturated fatty acid of 18 carbon atoms.

For present purposes, it has been found that Emery Acid 3101 R is particularly useful. This is monocarboxyli c acid having an equivalent weight of 310 and is sold commercially by the Emery Industries of Cincinnati, Ohio. It is described as a saturated lit-carbon atom fatty acid having methyl chain branching.

The polyalkylene polya-mines of the invention as mentioned above contain from 2 to 6 alkylene amine units with from 2 to 4 carbon atoms in each alkylene group. Illustrative amines include diethylenetriamine, triethylenetetraamine, tetraethylenepentaamine, hexaethyleneheptaamine, heptaethyleneoctaamine, tetrapropylenepentaamine, hexabutyleneheptaamine and the like. For present purposes triethylenetetraamine and tetraethylpentaamine are preferred for availability and efiectiveness of the polyamides prepared from them.

The following examples are illustrative of typical methods for preparing the polyamide of the invention and of lubricant compositions containing it.

Example I In this example the polyamide of tetraethylenepentaamine and a 10:90 mixture of straight and branchedchain acids is prepared.

A reaction vessel is charged with a mixture of 3.7 parts by Weight of tetraethylenepentaamine and 0.0002 part by weight of silicone foam inhibitor. The mixture is blanketed with nitrogen gas and heated to about 250 F. A mixture of monocarboxylic acids amounting to about 18.2 parts by Weight is introduced to the reaction vessel. This mixture consists of 10 mole percent stearic acid and 90 mole percent Emery 3101 R acid. The mole ratio of tetraethylenepentaamine to total acid is about 1 to 3. The reaction mixture is heated to about 300 F. for a period of about 1 hour and water of reaction is removed. Following this the reaction temperature is raised to about 400 F. at attmospheric pressure for about one hour and then maintained at about 380 F. under a vacuum equivalent to 4 mm. of mercury pressure for a period of about 7 hours.

Example 11 This example illustrates the preparation of the polyamide of tetraethylenepentaamine and a 5:95 mixture of straight and branched-chain acids.

To a 2-liter, 3-neck flask equipped with stirrer thermometer, reflux condenser and means of heating, there is charged 189 g. of tetraethylenepentaamine (1.0 mole) and 0.01 g. of silicon foam inhibitor. The charge is heated under nitrogen to about 190 F. A mixture of 42 g. stcaric acid (0.15 mole) and 873 g. Emery 3101 R acid (2.85 moles) is then added. The contents of the flask are heated to 380 F. and then put under a vacuum equivalent to about 20 mm. of mercury pressure. The reaction mixture is held under these conditions for about six hours and then cooled. Then yield of product is quantitative.

Example III In this example the polyamide of tetraethylenepentaamine and a 20:80 mixture of straight and branched-chain acids is prepared.

In accordance with the procedure outlined in Example II above, 189 g. of tetraethylenepentaamine, 1 6 8 g. of stearic acid (20 mole percent of total acid) and 744 g. of Emery 3101 R acid (80 mole percent of total acid) are reacted. A total of 3.0 moles of acid per mole of tetraethylenepentaamine is used. The yield of the product amounts to about 100% on the basis of the reactants.

In general, excellent detergent and pour depressant properties can be imparted to lubricating oils by dissolving therein a quantity of from about 0.1 to 10% y weight of the polyamide of the type described above, although a preferred range is from about 1 to 5% y Weight; On the other hand, since the polyamide of this invention is unusually compatible with mineral and other lubricating oils in substanti lly all proportions, as much a as of the present polyamide additives can be dissolved in a suitable lubricating oil for the purpose of preparing a concentrate capable of dilution with lubricating oils and the like to prepare the final lubricant composition. Such concentrates, which may also contain other additives in desired amounts, and which normally contain at least 1 0% of the polyanride, comprise a convenient method for handling the polyamide and may be used as a compounding agent for lubricants in general.

The polyamide additives of this invention can be used with good effect in the case of any one of a wide variety of oils of lubricating viscosity, or of blends of such oils. Thus, the base oil can be a refined Pennsylvania or other paraffin base oil, a refined naphthenic base oil, or a synthetic hydrocarbon or non-hydrocarbon oil of lubricating viscosity. As synthetic oils there can be mentioned alkylated waxes similar alkylated hydrocarbons of relatively high molecular Weight, hydrogenated polymers of hydrocarbons, and the condensation products of chlorinated alkyl hydrocarbons with aryl compounds. Other suitable oils are those which are obtained by polymerization of lower molecular weight alkylene oxides such as propylene and/ or ethylene oxide. Still other synthetic oils are obtained by etherification and/or esterification of the hydroxy groups in alkylene oxide polymers, such as, for example, the acetate of the 2-ethylhexaaol-initiated polymer of propylene oxide. Other important classes of synthetic oils include the various esters as, for example, di- -(2-ethylhexyl)sebacate, tricresyl phosphate and silicate esters. If desired, the oil can be a mixture of mineral and synthetic oils. For present purposes the polyamide of this invention finds its greatest utility in waxy mineral lubricating oils and such compositions are therefore preferred.

While satisfactory lubricant compositions can be obtained by adding to the base oil employed only one or more of the polyamide additives of the type described above, it also falls within the purview of this invention to provide lubricant compositions which containnot only such polyamides but also other additives such as oiliness, and extreme pressure agents, anti-oxidants, corrosion inhibiting agents, blooming agents, thickening agents and/ or compounds for enhancing the temperature-viscosity characteristics of the oil.

Illustrative lubricant compositions of the above type containing the polyamide additives of the invention in combination with other agents may include, for example, from about 0.1 to 10% by weight of alkaline earth metal higher alkylphenate detergent and Wear reducing agents 7 such as calcium alkyiphenates having an average of approximately 14 carbon atoms in the alkyl group as well as organic thiophosphate corrosion and high. temperature oxidation inhibitors such as the reaction product of pinene and P 8 and the bivalent metal dithiophosphate and zinc tetradecylphenyl dithiophosphate in amounts. of from about 0.1 to 10% by weight of the composition. Temperature-viscosity improving agents which may be em ployed in the compositions, usually in amounts of from about 1 to 10% by Weight, include by Way of example the homopolymers of alkyl methacrylates such as the dodecyl methacrylate polymers known to the trade as Acryloid 710 and Acryloid 763, products of Rohrn & Haas Company, and high molecular weight butene polymers such as Paratone ENl 15P, a product of the Enjay Corn pany.

The polyamide additives of the invention as described above are evaluated as pour depressants in lubricating oils in a number of tests. The base oil is a solvent-refined waxy SAE 30 mineral lubricating oil having a pour point of +10 F. The results of the tests are set out in the following table. For convenience a typical polyarnine, namely, tetraethylenepentaamine is selected and the illustrative acids chosen are stearic acid and Emery 3101 R acid. The pour point tests are performed in accordance with ASTM method D97. The sample is maintained at a temperature of 115 F. or lower for at least 24 hours prior to the test. The sample is then cooled systematically under quiescent conditions and observed at intervals of 5 F. The pour point is the lowest temperature at which the oil flows when the container is tilted.

Stean'c acid, mole percent: Pour point or" oil, F.

As shown by the test results of the above table the polyamide additive of this invention imparts surprisingly improved pour point characteristics to lubricant compositions compared to similar compositions containing polyamides of conventional types.

It is further evident that the improved pour point characteristics of the polyamides of this invention are due to the particular proportions of straight-chain fatty acid and branched-chain fatty acid and that proportions Within the preferred ranges provide pour ponits which are unpredictably lower than mixtures of other proportions of acids.

I claim:

1. A lubricant composition comprising a major proportion of a waxy mineral lubricating oil and a minor proportion sufiicient to enhance the pour point characteristics of the composition of a polyamide of fatty acids and tetraethylenepentaamine in which the fatty acids are mixtures of from about 5 to about 30 mole percent of straight-chain fatty acids and of from about to about 95 mole percent of branched-chain fatty acids, said fatty acids containing from about 12 to about 30 carbon atoms each and said polyamide containing from about 1 to about 3 amine groups in addition to amide groups.

2. A lubricant composition comprising a major proportion of a waxy mineral lubricating oil and a minor proportion sufficient to enhance the pour point characteristics of the composition of a polyarnide of fatty acids and tetraethylenepentaamine in which the fatty acids are mixtures of from about 5 to about 30 mole percent of stearic acid and from about 70 to about '95 mole percent of methyl branched-chain fatty acid containing about 18 carbon atoms, said polyamides containing from 1 to 3 amine groups in addition to amide groups.

3. A lubricant composition comprising a major propotion of a Waxy mineral lubricating oil and from about 0.1 to about 10% by Weight of a polyamide of fatty acids and tetraethylenepentaamine in which the fatty acids are mixtures of from about 5 to about 30 mole percent of stearic acid and from about 70 to about 95 mole percent of methyl branched-chain fatty acid containing about 18 carbon atoms, said polyamide containing from 1 to 3 amine groups in addition to amide groups.

4. A lubricant composition comprising a major proportion of a waxy mineral lubricating oil and from about 0.1 to about 10% by weight of a polyamide of fatty acids and tetraethylenepentaamine in which the fatty acids are mixtures of from about 10 mole percent of stearic acid and from about mole percent of methyl branched-chain fatty acid acid containing about 18 carbon atoms, said polyamide containing from 1 to 3 amine groups in addition to amide groups.

5. A lubricant composition comprising a major proportion or" a waxy mineral lubricating oil and from about 0.1 to about 110% by weight of a polyamide of fatty acids and tetraethylenepentaamine in which the fatty acids are mixtures of from about 5 mole percent of stearic acid and from about mole percent of methyl branched-chain fatty acid containing about 18 carbon atoms, said polyamide containing from 1 to 3 amine groups in addition to amide groups.

6. A lubricant composition comprising a major proportion of a waxy mineral lubricating oil and from about 0.1 to about 10% by weight of a polyamide of fatty acids and tetraethylenepentaamine in which the fatty acids are mixtures of from about 20 mole percent of stearic acid and from about 80 mole percent of methyl branched-chain fatty acid containing about 18 carbon atoms, said polyamide containing from 1 to 3 m'ne groups in addition to amide groups.

References Cited in the file of this patent UNITED STATES PATENTS 2,622,067 White et al Dec. 16, 1952 2,693,468 Blair Nov. 2, 1954 2,713,583 Smith July 19, 1955 2,736,658 Pfohl et al. Feb. 28, 1956

Claims

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR PROPORTION OF A WAXY MINERAL LUBRICATING OIL AND A MINOR PROPORTION SUFFICIENT TO ENHANCE THE POUR POINT CHARACTERISTICS OF THE COMPOSITION OF A POLYAMIDE OF FATTY ACIDS AND TETRAETHYLENEPENTAAMINE IN WHICH THE FATTY ACIDS ARE MIXTURES OF FROM ABOUT 5 TO ABOUT 30 MOLE PERCENT OF STRAIGHT-CHAIN FATTY ACIDS AND OF FROM ABOUT 70 TO ABOUT 95 MOLE PERCENT OF BRANCHED-CHAIN FATTY ACIDS, SAID FATTY ACIDS CONTAINING FROM ABOUT 12 TO ABOUT 30 CARBON ATOMS EACH AND SAID POLYAMIDE CONTAINING FROM ABOUT 1 TO ABOUT 3 AMINE GROUPS IN ADDITION TO AMIDE GROUPS.