US3018250A - Lubricating oil compositions containing nu-dialkylaminoalkyl alkenyl succinimides - Google Patents

Description

United States Patent Oflice LUBRICATING OIL COMPOSITIONS CONTAINING N-DIALKYLAMINOALKYL ALKENYL SUCCIN- IMIDES Robert G. Anderson, Novato, Frank A. Stuart, Orinda, and Alan Y. Drnmmond, Richmond, Calif., assignors to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Filed Aug. 24, 1959, Ser. No. 835,390

8 Claims. (Cl. 252-515) This invention pertains to lubricating oil compositions containing N-dialkylaminoalkyl alkenyl succinimides as detergents.

Alkenyl succinic anhydrides and numerous derivatives thereof are well known in the art. For example, alkenyl succinic anhydrides in which the alkenyl radical contains from to 20 carbon atoms are taught as corrosion in hibitors in lubricating compositions. Also, products obtained by reacting such alkenyl succinic anhydrides with monoamines are taught as ferrous corrosion inhibitors for lubricating oil compositions.

However, the above known alkenyl succinimides are not useful as detergents for lubricating oil compositions. In contrast thereto, the alkenyl succinimides described herein are useful as detergents in lubricating oil compositions.

Present clay internal combustion engines operate at high speeds and high compression ratios. When used in the so-called city stop-and-go driving, which includes the greater part of the driving condition for a large percentage of todays automobiles, the internal combustion engin es do not reach the most efficient operating temperature. Under. city driving conditions, large amounts of particle oxidation products are formed, and reach the crankcase of the engine by blowing past the piston rings. Most of these partial oxidation products are oil insoluble, tending to form deposits on the various operating parts of the engine, such as the pistons, piston rings, etc. For the purpose of preventing the deposition of these products on the various engine parts, it is necessary to incorporate detergents in the lubricating oil compositions, thus keeping these polymeric products highly dispersed in a condition unfavorable for deposition on metals.

For the most part, the various detergents which are fectiveness as detergents for dispersing the precursors of sludges and varnishes are metal organic compounds, particularly those compounds wherein the metal is linked to an organic group through an oxygen atom. Although these metal-containing organic compounds have some effectiveness as detergents for dispersing the precursors of deposits within the oil itself rather than permitting them to form added deposits on the engine parts, they have the disadvantage of forming ash deposits in the engine. These ash deposits lower engine performance by fouling the spark plugs and valves and contributing to preignition.

It is a particular object of this invention to set forth lubricting oil compositions containing new compounds which are particularly useful as metal-free detergents.

Therefore, in accordance with this invention, it has been discovered that lubricating oil compositions particularly useful for heavy duty service are obtained by intaining-these alkenyl succinimides, diesel and-gasoline engine parts remain remarkably free of deposits and varnish even under severe operating conditions.

The N-dialkylaminoalkyl monoalkenyl succinimides wherein the alkenyl radical contains from 30 to 200 carbon atoms, and wherein said dialkylaminoalkyl radical contains a total of 3 to 10 carbon atoms, can be represented by the formula:

wherein R is an alkenyl radical containing from 30 to 200 carbon atoms, R is a divalent alkylene radical, and R and R are alkyl radicals. The sum of the carbon atoms in the R, R and R is from 3 to 10; that is, R,

R and R contain a total of no more than 10 carbon atoms.

It is particularly preferred that R is a polymer of an" olefin containing from 2 to 5 carbon atoms, wherein the polymer has a molecular weight from 400 to 3000, more particularly from about 900 to about 1200. Such olefins are exemplified by ethylene, propylene, l-buteue, 2-butene, isobutene, and mixtures thereof. Since the methods of polymerizing the olefins to form polymers thereof is immaterial in the formation of the new compound described herein, any of the numerous processes available can be used therefor.

R' alkylene radicals include the divalent ethylene radical, propylene radical, butylene radical, etc. R and R alkyl radicals include methyl, ethyl, propyl, etc. It is particularly preferred that R' contains 3 carbon atoms, and that R and R each contain 1 carbon atom.

Amine reactants for the formation of N-dialkylaminoalkyl alkenyl succinimidesinclhded dimethylarninomethylamine, dimethylaminoethylamine, dimethylaminopropylamine, dimethylaminobutylamine, dimethylaminoheptylamine, diethylaminomethylamine, diethylaminopropylamine, diethylaminoamylamine, dipropylaminopropylamine, methylpropylaminoamylamine, propylbutylaminoethylamine, etc.

The preparation of the monoalkenyl succinimides herein can be described generally by the following equations, wherein a polyolefin is reacted with maleic anhydride to form a monoalkenyl succinic anhydride, which, in turn, is then reacted with a dialkylaminoalkylamine to form an N-dialkylaminoalkyl monoalkenyl succinimide. Using a polymer of isobutene as an example of the alkenyl radical, and dimethylaminopropylamine to exemplify the dialkylaminoalkylamine, these equations are as follows:

Patented Jan. 23, 1962 Y The above reaction between a polyolefin and maleic anhydride is an uncatalyzed addition reaction which should not be confused with a copolymerization reaction such as that obtained with a vinyl monomer and maleic anhydride. While the general reaction of an olefin and maleic anhydride is well known for olefins of low molecular weight (e.g., olefins of 18 carbon atoms), no previous work has been done with maleic anhydride and the high molecular weight olefins as described herein.

In the second step of the reaction as exemplified in Equation 11 hereinabove, the reactants are used in such proportions and the reaction conditions are such that an imide is formed, not a diamide.

The reaction set forth and described by Equation I hereinabove can proceed in a mol ratio of the polyolefin to the 'maleic anhydride of 1:1 to 1:10; preferably from 1:1 to 1:5. The reaction temperature can vary from 300 F. to 450 F. Because of the greater yield obtained thereby, it is preferred to use the higher temperature range (e.g., 375 F. to 450 F.).

In the second step of the reaction as exemplified by Equation H hereinabove, the yield of the imide is extremely high even though the reactants are used in equal molar ratios.

The reaction described by Equation 11 hereinabove can be made at 220 F. to 500 F., preferably from 300 F. to 400 F. The alkenyl succinic anhydride and the polyamine are reacted in about equal molar quantities. An excess of amine can be used, and the unreacted amine removed by distillation.

Since the reaction between the polyolefin and maleic anhydride may not go to completion, the resulting alkenyl succinic anhydride may contain some unreactedpolyolefin. As it may not be desirable to separate out this unreacted polyolefin at this stage, the resulting imide formed by reaction of the alkenyl succinic anhydride and the diamine will contain this polyolefin as an impurity which can be a diluent in the formation of lubricating oil compositions. However, if it is so desired, this unreacted polyolefin can be removed by precipitation, for example, by aceton or methanol from a hydrocarbon solution.

The preparation of N-dialkylaminoalkyl monoalkenyl succinimides is illustrated in the following examples.

Example I.-Preparatin of polybutenyl succinic anhydride A mixture of 1000 grams (1 mol) of a polybutene having a molecular weight of about 1000 and 98 grams (1 mol) of maleic anhydride was heatedat 410 F. in a nitrogen atmosphere with agitation for a period of 24 hours. The reaction mixture was cooled to 150 F., and 700 cc. of hexane added; after which the mixture was filtered under vacuum. After vacuum distillation to remove the hexane from the filtrate, the product was maintained at 350 F. at an absolute pressure of mm. Hg for one hour to remove traces of maleic anhydride. The crude polybutenyl succinic anhydride thus prepared had a saponification number of 79.

Example II.-Preparation of N-dimethylaminopmpyl polybutenyl succinimide A mixture of 21.3 grams (0.21 mol) of dimethyl- CH: C H! H CH --CH:CH:C CH3 NCHICH CHPN Hr-C I aminopropylamine and 150 grams (0.09 mol) of the polybutenyl succinic anhydride of Example I hereinabove, was blended with agitation in a nitrogen atmosphere, and the mixture was heated at 500 F. for a period of one hour, after which the absolute pressure was reduced to about 200 mm. Hg at this temperature during a period of 30 minutes to facilitate the removal of water and excess amine. The reaction mixture was then allowed to reach room temperature at this reduced pressure. The reaction product contained 1.7% nitrogen (theory: 1.8%). The identity of the N-dimethylaminopropylalkenyl succinimide was established by means of infrared spectroscopy.

Table I hereinbelow presents further data concerning the preparation of N-dialkylaminoalkyl alkenyl succinimides. The polyamine was dimethylaminopropylamine, and the alkenyl radical on the alkenyl succinimide was a polybutene, the molecular weight of which is noted in Table 'I.

1 Polyisobutenyl succinic anhydride.

As lubricating oil additives, these alkenyl 'succinimides can be used in amounts'of 0.1% to by weight, preferably 0.25% to 5%, by weight.

Lubricating oils which can be used as base oils for lubricating oil compositions of such alkenyl succinimides include a wide variety of lubricating oils, such as naphthenic base, paraflin base, and mixed base lubricating oils, other hydrocarbon lubricants, e.g., lubricating oils derived from coal products, and synthetic oils, e.g., alkylene polymers (such as polymers of propylene, butylene, etc., and the mixtures thereof), alkylene oxide-type polymers (e.g., alkylene oxide polymers prepared by polymerizing the alkylene oxide, e.g., propylene oxide, etc., in the presence of water or alcohols, e.g., ethylene alcohol), dicarboxylic acid esters (e.g., those which are prepared by esterifying such dicarboxylic acids as adipic acid, azelaic acid, suberic acid, sebacic acid, alkanol succinic acid, fumaric acid, maleic acid, etc., with alcohols, such as butyl alcohol, hexyl alcohol, Z-ethylhexyl alcohol, dodecyl alcohol, etc.), liquid esters of acids of phosphorus, alkyl benzenes, polyphenyls-(e.g., biphenyls and terphenyls), alkyl biphenyl ethers, polymers-of silicon (e.g., tetraethyl silicate, tetraisopropyl silicates, tetra (4- methyl-Z-tetraethyl) silicate, hexyl (4-methyl-2-pentoxy) disiloxane,'poly(methyl) siloxane, and poly(methylphenyl) siloxane), etc.

The above base oils may be used individually or in combinations thereof, wherever miscible or wherever made so by the use of mutual solvents.

Table II hereinbelow sets forth data showing the dicetiveness of N-dialkylaminoalkyl monoalkenyl succinimides as lubricating oil additives.

The succinimide used was an N-dimethylaminopropyl alkenyl succinimide wherein the alkenyl radical had a molecular weight of approximately 1000, which alkenyl radical was a polymer of isobutene.

The base oil was an SAE 10 base oil.

The data were obtained in a Caterpillar L-l test under Mil-L-2104 conditions for 120 hours.

The PD Nos. refer to the piston discoloration rating. After the engine test, the three piston lands are examined visually. To a piston land which is completely black is assigned a PD number of 800; to one which is completely clean, a PD number of to those intermediate between completely black and completely clean are assigned PD numbers intermediate in proportion to the extent and degree of darkening.

The GD Nos. refer to the percentage deposits in the piston ring grooves; an 0 evaluation being a clean groove;

and a number of 100 being a groove full of deposits.

Table III hereinbelow presents data showing the efiectiveness of these alkenyl succinimides in inhibiting piston varnish formation. These tests were obtained in an FL-Z test, using a 6-cylinder Chevrolet engine operating at 2500 r.p.m. for a period of 40 hours. This test is fully described in a Coordinating Research Council Bulletin entitled Research Technique for the Determination of the Efiects of Fuels and Lubricants on the Formation of Deposits During Moderate Temperature Operation (1948).

The piston varnish rating is a visual observation of the amount of varnish on a piston skirt, with 10 being the rating of a clean piston and "0" the rating of a piston fully covered with black varnish. This piston varnish rating correlates with road performance.

The dithiophosphate was a zinc salt of a mixed dialkyl dithiophosphate wherein one of the alkyl radicals contained 4 carbon atoms and the other alkyl radical contained 5 carbon atoms. The dithiophosphate concentration is expressed as millimols per kilogram (i.e., mMJkg.)

of finished product.

TABLE III Additive C D E F G succinimide, Wt. percent 0. 0 1. 0 0.6 l l. 6 2. 0 Dithiophosphate, mMJkg 0. 0 0. 0 13 18 18 Test Results:

Piston Varnish Rating 2. 5 6.2 6. 9 7. 0 7.7

The alkenyl radical of the succinimide was an isobutene polymer having a molecular weight of about 700.

It is readily seen from the data set forth hereinabove that lubricating oil compositions containing the succinimides described herein are markedly eifective for the lubricating of internal combustion engines.

In addition to the dithiophosphates described hereinabove, lubricating oil compositions containing the N-dialkylaminoalkyl alkenyl succinimides. of this invention may also contain other detergents, viscosity index improving agents, rust inhibitors, oiliness agents, grease thickening agents, etc.

What is claimed is:

1. A lubricating oil composition comprising a major proportion of an oil of lubricating viscosity, and, in an amount to impart detergency thereto, an N-dialkylaminoalkyl monoalkenyl succinimide, wherein said alkenyl radical contains from 30 to about 200 carbon atoms, and said dialkylaminoalkyl radical contains no more than 10 carbon atoms.

2. A lubricating oil composition comprising a major proportion of an oil of lubricating viscosity, and, in an amount to impart detergency thereto, an N-dialkylamino- 75 2,638,450

alkyl monoalkenyl succinimide, wherein said alkenyl radical is a polymer of an olefin containing from 2 to 5 carbon atoms, which polymer has a molecular weight from about 400 to about 3000, and said dialkylaminoalkyl radical contains from 3 to 10 carbon atoms.

3. A lubricating oil composition comprising a major proportion of an oil of lubricating viscosity, and, in an amount to impart detergency thereto, an N-dialkylaminoalkyl monoalkenyl succinimide, wherein said alkenyl radical is a polymer of an olefin containing from 2 to 5 carbon atoms, which polymer has a molecular weight from about 900 to about 1200, and said dialkylaminoalkyl radical containing from 3 to 10 carbon atoms.

4. A lubricating oil composition consisting essentially of an oil of lubricating viscosity and from 0.1% to by weight, of an N-dialkylarninoalkyl monoalkenyl succinimide wherein said alkenyl radical contains from 30 to about 200 carbon atoms, and said dialkylaminoalkyl radical contains from 3 to 10 carbon atoms.

5. A lubricatng oil composition comprising a major proportion of an oil of lubricating viscosity from 0.25%

to 5%, by weight, of an N-dialkylaminoalkyl monoalkenyl of an oil of lubricating viscosity, and from about 0.1% i

to about 80%, by weight, of an N-dialkylaminoalkyl monoalkenyl succinimide of the formula:

0 R-CHC R I wherein R is a hydrocarbon radical derived from a polymer of an olefin containing from 2 to 5 carbon atoms, said polymer having a molecular weight in the range of about 900 to about 1200, and R, R and R are aliphatic hydrocarbon radicals containing a sum total of 3 to 10 carbon atoms.

7. A lubricating oil composition comprising a major proportion of a petroleum lubricating oil, and from about 0.25% to about 5%, by weight, of an N-substituted monoalkenyl succinimide of the formula:

0 RCHC n \NR-N/ 52-0; R1

wherein R is a polymer of isobutene having a molecular weight of about 1000, and R, R and R are aliphatic GET-C CH3 0 wherein R is a polymer of an olefin containing 4 carbon atoms, said polymer having a molecular weight of about 1000.

References Cited in the file of this patent UNITED STATES PATENTS 2,490,744 Trigg et al Dec. 6, 1949 Rocchini July 22, 1952- White May 12, 1953 UNITED. STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 3,018,250 I Janua lfyw23 1962 I Robert G, Anderson et a1.

It '1: hereby certified that error appears in the above numbered atant requiring. correction and that the said Letters Patent should read as corrected below.

Column 1, line 45 strike out "fectiveness as detergents for dispersing the precursors" and insert instead add to crankcase oils to reduce this formation Signed and sealed this 5th day of June 1962;

(SEAL) Atteat:

ERNEST w. SWIDER L- LADD Atteating Officer Cominiaeioner of Patents

Claims (1)

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF AN OIL OF LUBRICATING VISCOSITY, AND, IN AN AMOUNT TO IMPART DETERGENCY THERETO, AN N-DIALKYLAMINOALKYL MONOALKENYL SUCCINIMIDE, WHEREIN SAID ALKENYL RADICAL CONTAINS FROM 30 TO ABOUT 200 CARBON ATOMS, AND SAID DIALKYLAMINOALKYL RADICAL CONTAINS NO MORE THAN 10 CARBON ATOMS.