US3361673A - Lubricating oil compositions containing alkenyl succinimides of tetraethylene pentamine - Google Patents

Description

United States Patent LUBRICATING GIL COMPOSITIONS CONTAENING ALKENYL SUCCINIMIDES 0F TETRAETHYL- ENE PENTAMINE Frank A. Stuart, Oriuda, Robert G. Anderson, Novato, and Alan Y. Drumrnond, Richmond, Calitl, assignors to Chevron Research Company, a corporation of Delaware No Drawing. Filed Aug. 24, 1959, Ser. No. 835,437

6 Claims. (Cl. 252-515) This invention pertains to lubricating oil compositions having incorporated therein metal-free detergents. These particular metal-free detergents are N-substituted polyamine alkenyl succinimides.

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 inhibitors in lubricating oil compositions. Also, products obtained by reacting such alkenyl succinic acid anhydrides with monoamines are taught as ferrous corrosion inhibitors for lubricating oil compositions.

However, the above known alkenyl succinimides are not useful as detergents in lubricating oil compositions. In contrast thereto, the N-substituted polyamine alkenyl succinimides which are described herein are new compounds which are useful as detergents in lubricating oil compositions.

Present day 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 engines do not reach the most efficient operating temperature. Under city driving conditions, large amounts of partial 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 added to crankcase oils to reduce this formation of sludges and varnishes are metal organic compounds, particularly those compounds wherein the metal is linked to an or ganic group through an oxygen atom. Although these metal-containing organic compounds have some etfectiveness as detergents for dispersing the precursors of deposits within the oil itself rather than permitting Patented Jan. 2, 1968 lubricating oil compositions which are compounded with a metal-free detergent.

Therefore, in accordance with this invention, it has been discovered that lubricating oil compositions particularly useful for heavy duty service are obtained by incorporating N-substituted monoalkenyl succini-rnides derived from tetraethylene pentamine in oils of lubricating viscosity.

By the use of lubricating oil compositions containing the N-substituted alkenyl succinimides described herein, diesel and gasoline engine parts remain remarkably free of deposits and varnish, even under severe operating conditions.

These new compounds, which are monoalkenyl succinimides of tetraethylene pentamine, have the formula:

wherein R is a hydrocarbon radical having a molecular Weight from about 400 to about 3000; that is, R is a hydrocarbon radical containing about 30 to about 200 carbon atoms.

These alkenyl succinimides of tetraethylene pentamine can be prepared by reacting maleic anhydride with an olefinic hydrocarbon, followed by reacting the resulting alkenyl succinic anhydride with tetraethylene pentamine. The R radical of the above formula, that is, the alkenyl radical, is derived from an olefin containing from 2 to 5 carbon atoms. Thus, the alkenyl radical is obtained by polymerizing an olefin containing from 2 to 5 carbon atoms to form a hydrocarbon having a molecular weight ranging from about 400 to about 3000, more preferably, 900 to 1200. Such olefins are exemplified by ethylene, propylene, l-butene, Z-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.

The preparation of N-substituted monoalkenyl succinimides derived from tetraethylene pentamine can be described generally by the following equations, using a polymer of isobutene as an example of the alkenyl radical: I 0

them to form added deposits on the engine parts, I they have the disadvantage of forming ash deposits in the C 3 engine. These ash deposits lower engine performance by CH:C fouling plugs and valves, and contributing to preignition. 11

CH3 CH3 CH3 0 l I CH3CCH2-OH?' CH=CCH2OHC\ GEM-CH2 CHa n /O NH:C2H4N /NH 011 -0 CH2-CH2 CH3 CH3 CH 0 I I GHaCCHz-CHCIJ OH=CCHCHC\ CHPCHQ CH3 /n /NCH2CH2N /NH CHz-O CHa-CH:

It is a particular object of this invention to provide wherein n has a value of about 7 to about 50.

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.

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 of products obtained thereby, it is preferred to use the high range of temperatures (e.g., 375 F. to 450 F.). In the second step of the reaction as exemplified by Equation II hereinabove, the yield of the imide is extremely high even though the reactants are used in equal molar ratios. This is surprising, since under the conditions of the reaction there is an excess of secondary amino groups over primary amino groups, and any reaction with the secondary amino groups would lead to amide formation; thus, preventing imide formation.

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 tetraethylene pentamine are reacted in about equal molar quantities.

Since the reaction between the polyolefin and maleic anhydride may not go to completion, the resulting alkenyl succinic anhydride may contain some unreacted polyolefin. 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 acetone or methanol from a hydrocarbon solution.

Lubricating oils which can be used as base oils 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., propylene oxide polymers) and derivatives, including alkylene oxide polymers prepared by polymerizing the alkylene oxide in the presence of water or alcohols, e.g., ethyl alcohol, dicarboxylic acid esters (such as those which are prepared by esterifying such dicarboxylic acids as adipic acid, azelaic acid, suben'c acid, sebacic acid, salkanol succinic acid, fumaric acid, maleic acid, etc., with alohols such as butyl alcohol, hexyl alcohol, 2-ethyl hexyl alcohol, dodecyl alcohol, etc.), liquid esters of acids of phosphorus, alkyl benzenes (e.g., monoalkyl benzene such as dodecyl benzene, tetradecyl benzene, etc., and dialkyl benzenes (e.g., n-nonyl Z-ethyl hexyl benzene); polyphenyls (e.g., biphenyls and terphenyls), alkyl biphenyl ethers, polymers of silicon (e.g., tetraethyl silicate, tetraisopropyl silicates, tetra(4-methyl-2-tetraethyl) silicate, hexyl (4-methyl-2-pentoxy) disiloxane, poly(methyl) siloxane, poly(methylphenyl) siloxane, etc. Synthetic oils of the alkylene oxide-type polymers which may be used include those exemplified by the alkylene oxide polymers.

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

The alkenyl succinimides of tetraalkylene pentamine can be used in oils of lubricating viscosity in amounts of 0.1% to 80%, by weight, preferably 0.25% to 5%, by weight.

The preparation of the alkenyl succinimides of tetraalkylene pent-amine is illustrated in the following examples.

Example I.-Preparati0n 0f polybutenyl succinic anhydride A mixture of 1000 grams (1 mol) of polybutene having a molecular weight of about 1000 and 98 grams (1 mol) of maleic anhydride was heated at 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 10 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 I1.Preparati0n of tetraethylenepentamine derivative 0 the polybutenyl succinic anhydride of Example l hereinabove A mixture of 84 grams (0.45 mol) of tetraethylene pentamine and 702 grams (0.45 mol) of the polybutenyl succinic anhydride of Example I hereinabove, was blended with agitation at 125 F. in a nitrogen atmosphere. The temperature was increased to 400 F. during a period of one hour, after which the absolute pressure was reduced to about 200 mm. Hg during a period of 30 minutes to facilitate the removal of water. The reaction mixture was then allowed to reach room temperature at this reduced pressure. The reaction product contained 5.1% nitrogen (theory=5.4%). Infra-red analysis showed that the reaction product was an imide containing a polybutene side chain.

As detergents for lubricating oil compositions, the compounds of this invention are more efiective than alkenyl succinimides having fewer nitrogen atoms in the amine portion of the molecule, and succinimides having less than 30 carbon atoms in the alkenyl radical. The use of amyl amine, for example, in place of tetraethylene pentamine in the preparation of the succinimide, results in a product which is ineffective as a detergent in lubricating oil compositions.

Table I hereinbelow presents data obtained with lubricating oil compositions containing N-substituted monoalkenyl succinimides derived from tetraethylene pentamine.

The monoalkenyl succinimide used was an N-substituted succinimide derived from tetraethylene pentamine Wherein the alkenyl radical had a molecular weight of about 1000, which alkenyl radical was a polymer of isobutene.

The tests were made in a Caterpillar L-l engine according to Supplement I conditions for a period of 120 hours as described in the Coordinating Research Council Handbook, January, 1946.

The PD Nos. refer to the piston discoloration rating. After the engine test, the three piston lands are examined visually. To a piston skirt which is completely black is assigned a PD number of 800; to one which is completely clean, a PD number of 0; to those intermediate between completely black and completely clean are assigned PD numbers intermediate in proportion to the extent and degree of darkening.

The G.D. Nos. refer to the percentage deposits in the piston ring grooves; and 0 evaluation being a clean groove; and a number of 100 being a groove full of deposits.

The base oils were California SAE 30 base oils.

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 was present in the lubricating oil compositions in an amount of 18 millimols per kilogram (Le, 18 mm./kg.) of finished product, based on the metal content.

TABLE I A I B o D Additive:

Succiniuu'de, Wt. percent- 0.0 3. 2. 0 Dithiophosphate:

(1) ImJkg 0.0 0.0 18 18 (2) MIn./kg 0.0 0.0 Test Results:

G.D. No 2 39 4 21 1 P.D. N0 2 800, 800, 800 0, 0, O 600, 300, 200 40, 1, 5

1 An alkenyl succinimide of tetraethylene pentamine wherein the allrenyl radical has had a molecular weight of approximately 1,000, which alkenyl radical was a polymer of isooutene 2 These test results were obtained in a Caterpillar L-l test under the MIL-D2104 conditions. Thus, under the more severe supplement-l conditions, these G.D. N as. would be considerably higher.

The marked synergistic efiect obtained by the combina- T ABLE 1H tron of the N-substituted alkenyl succinimides of this invention and the dithiophosphates is particularly noted. I I l I K i L Table II hereinbelow presents data obtained in an FL-2 ti 0 Additive: test, usmg a 6 cylinder Chevrolet engine Opera 11,, fiat succinimide, Wt percent 3'0 3'0 3' 0 3 0 2500 r.p.m for a period of 40 hours, which test is in y Dithiopl1osphate,mm./kg 1s 18 18 18 described in a Coordmatmg Research Council. bulletm Test Results! -t it th Duration of Test (hours) 20 36 52 72 tled Research Technique for the Determination of e gearing Weight 133 133 206 240 Efiects of Fuels and Lubricants on the Formation of De- Plston Varnish Refine posits 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 maximum rating for a perfectly clean piston and a 0 being the rating of a piston fully covered with black varnish. This piston varnish rating correlates with road performance in automobiles.

The total rating is the overall deposit rating of the engine. The rating values range from 0, the poorest value, to 100, the top value. These figures indicate the percentage rating for the engine.

The base oil was an SAE base oil.

The succinimide and the dithiophosphate were the same as those described for Table I hereinabove.

It is readily seen from the data set forth hereinabove in Tables I and II that lubricating oil compositions containing the alkenyl succinimides of tetraethylene pentamine as described herein are superior as lubricating oil compositions for the lubricating of internal combustion engines.

Table 111 hereinbelow presents data obtained with lubricating oil compositions under L-4 test conditions. This L-4 engine test which is fully described in the CRC Handbook, 1946 edition, Coordinating Research Council, New York, New York, is designed to evaluate the bearing corrosion characteristics and high temperature detergency of lubricating oil compositions. The detergency characteristics are rated by the piston varnish rating on the same scale described above for the FL-2 test. The L-4 test was continued beyond the normal 36 hours. The number of hours is the hours at which the same specimens were evaluated then placed in the engine for further testing.

The dithiophosphate was a zinc salt of a dialkyl dithiophosphate wherein one of the alkyl radicals contained 4 carbon atoms and the other alkyl radical contained 5 carbon atoms.

The succinimide and the dithiophosphate were the same as those described hereinabove.

This performance is exceptionally good.

As is known, the use of a number of polymeric ashless detergents and V1. improvers in lubricating oil compositions results in the formation of lead deposits on many of the parts of gasoline engines. These deposits result from the lead halides formed from the tetraethyl lead and the scavengers used in commercial gasolines. Engine failures result from the formation of these deposits. As shown by the data of Table I hereinbelow, the addition of the N-substituted alkenyl succinimides of this invention markedly improves the performance of such oils.

These tests, which correlate with actual road performance, were made in a 6-cylinder Chevrolet engine run at 2500 r.p.m., with 50 brake horsepower, an oil sump temperature of F. for a period of 36 hours, using a commercial gasoline containing 3 cc. of TEL per gallon. The oil was changed after 24 hours.

The lead rating scale ranges from 10 for a clean engine, to zero for an engine containing heavy lead deposits. Similarly, in the same engine test, piston varnish ratings were obtained, a value of 10 for a clean piston, and a value of zero for a piston heavy with varnish.

The succinimide and the dithiophosphate were the same as that described in the tables hereinabove.

TABLE IV Additive: M Succinimide, weight percent 2 Dithiophosphate, mm./kg. 18 Test results:

Lead rating 9.4 Piston varnish rating 9.9 Total rating 99.1

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

We claim:

1. A lubricating oil composition comprising a major proportion of an oil of lubricating viscosity, and in an amount suficient to impart detergency characteristics thereto, a monoalkenyl succinimide of the formula:

7 wherein R is a hydrocarbon radical having a molecular weight of from about 900 to about 3000.

2. A lubricating oil composition consisting essentially of an oil of lubricating viscosity, and from about 0.1% to about 80%, by weight, of a monoalkenyl succinirnide of tetraethylene pentamine of the formula:

RGHi| J lTICH2CHz(NHCH2CH2)s-NH GHzC=-O wherein R is a hydrocarbon radical derived from a polymer of an olefin containing from 2 to carbon atoms, said polymer having a molecular weight in the range of about 900 to about 3000.

3. A lubricating oil composition consisting essentially of an oil of lubricating viscosity, and from about 0.1% to about 80%, by weight, of a monoalkenyl succinirnide of tetraethylene pentamine of the formula:

i RCH(3 NGHzCHz(NHCHzCHg)g-NH1 CH2C=O wherein R is a 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.

wherein R is a polymer of isobutene having a molecular Weight of about 1000.

5. 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:

in which structural formula R is a substantially aliphatic hydrocarbon radical of from to 200 carbon atoms, with an equal molar quantity of tetraethylene pentamine at a temperature in the range of 220 to 360 F.

References Cited UNITED STATES PATENTS 2,490,744 12/ 1949 Trigg et a1 252-392 X 2,604,451 7/ 1952 Rocchini 252-515 2,638,450 5/1953 White et a1. 252-515 DANIEL E. WYMAN, Primary Examiner.

PATRICK P. GARVIN, JULIUS GREENWALD,

Examiners.

G. O. ENOCKSON, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,361,673 January 2, 1968 Frank A. Stuart et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 57, "plugs" should read spark plugs Columns 1 and 2, formula II should appear as shown below:

iIH (II-I (fH /O CHgC-CH CH- -C CH=C-CH -CH:C I

CH n /O H NCH CH (NHCH CH -NH CH CH CH O 3 3 3 CH -C-CH CH -IC CH=C-CH CH CH n /NCH CH (NHCH CH -NH CH --C Column 3, line 46, (such as polymers of propylene)" should read (such as polymers of propylene, Column 4, line 6, "of polybutene" should read of a polybutene Column 6, line. 35, "I"-should read IV same column 6, lines 69 to 75, the

formula should appear as shown below:

Signed and sealed this 16th day of December 1969.

(SEAL) Attest:

Attesting Officer Commissioner of Patents