CA1190216A - Succinimide lubricating oil dispersant - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
There is disclosed an improved lubricating oil dispersant suitable for both gasoline engine and diesel engine lubricating oil, the dispersant being prepared in a sequential process whereby a polyolefin succinic an-hydride is reacted first with an alkylene polyamine and subsequently with maleic anhydride, succinic anhydride, or a C1-C18 alkenyl or alkyl succinic anhydride to provide a diimide dispersant having a final mole ratio of 2.3 to 3.0 moles of anhydride per mole of polyamine.

Description

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1 lnis invention relates to lubricating oil

2 dispersants which exhibit highly efective dispersant

3 potency in both gasoline and diesel engines. More parti-

4 cularly, the invention rela~es to lubricating oil com-positions for use both in gasoline and diesel engine 6 formulations which meet current performance requirements 7 ~or both types o~ engines, the formulations being character-8 ized as containing novel dispersants prepared in a parti-9 cular reaction sequence.
A current objective in the i~dustry is to 11 provide lubricating oil compositions which meet or exceed 12 engine qualification standards of dispersancy for both 13 gasoline and diesel or compression ignition engines.
14 ~eretofore, dispersants have been developed which meet one or the other of these requirements, but development 16 of a dispersant which satisfies the highest service 17 classification requirements of the relevant enqine quali-18 fication tests for both types of oils has not been entirely 19 successful. It is an object of the present invention to provide lubrica~ing oil compositions containing novel 21 dispersants which meet these goals.
22 The present invention is within the broad 23 field of improved polyolefin, particularly polyisobutenyl, 24 succinic acid or anhydride-polyamine reaction product dispersants, and such dispersants are disclosed generally, 26 for example, in U.S. Patent 3,172,892 issued March 9, 27 1965 to LeSuer et al.
28 U.S. Patent 3,216,936 issued November 9, 1965 to 29 LeSuer shows lubricating oil additives prepared by acyla tion of an alkylene amine with both a polyolefin succinic 31 anhydride and an aliphatic monocarboxylic acid, preferably 32 a mono acid having more than 12 carbon atoms such as 33 stearic or oleic acid. The products can be prepared by 3~ reacting both acidic compounds simultaneously with a polyamine or by first reacting the polyolefin succinic 36 acid with polyamine and subsequently with monocarboxylic 37 acid. The products so formed are said to be particularly 2~i 1 useful in improving the thermal stability of lubricating 2 compositions which contain metal phosphorodithioates.
3 British Patent 1,018,982 (1966) discloses 4 lubricating oil additives which are the reaction products of three components: alkenyl succinic anhydrides, poly-6 amines and ca~boxylic acids and the products are said to 7 have improved sludge dispersant properties. The alkenyl 8 succinic anhydrides are those similar to the materials g of the present invention, i.e., preferably polyisobutenyl succinic anhydrides and the polyamines are also similar, 11 i.e., the alkylene polyamines. The carboxylic acids of 12 this reference are disclosed as being mono- or di~ car-13 boxylic acids having 1 to 30, preferably 1 to 18 carbon 14 atoms, with acetic acid being preferred since it forms an imidazoline or pyrimidine with a minimum of carbon 16 atoms. This reference also states that lower molecular 17 weight carboxylic acids are more effective in promoting the sludge dispersing activity of ~he final product.
18 The preparative method disclosed in British Patent 19 1,018,9B2 comprises either ~irst reacting the carboxylic acid and the polyamine in what is described as an imida-21 zoline or pyrimidine forming reaction with subsequent 22 reaction with alkenyl succinic anhydride or by reacting 23 the three materials simultaneously.
24 U.~. Patent 3,415,750 issued December 10, 1968 to Anzenberger discloses lubricant additives categorized 26 as imida201ines which are prepared by reacting a poly-27 ethylene polyamine with a mono-carboxylic acid or a di-28 carboxylic acid to form a heterocyclic imidazoline 29 intermediate which is subsequently reacted with a poly-alkenyl succinic anhydride to provide a bis-imidazoline 31 which is said to have improved detergency and dispersancy 32 in lubricating oil formulations.
33 U.S. Patent 3,374,174 issued March 19, 1968 to 34 LeSuer discloses lubricant additives prepared by reacting amines, including alkylene polyamines, with both a high 1 molecular weight saturated monocarboxylic acid and a 2 dicarboxylic acid or anhydride, preEerably those having 3 up to 12 carbons. The paterlt discloses the simultaneous 4 reaction of all three materials or a sequential process whereby there is first formed an acylated amine inter-6 mediate with the amine and high molecular weigh~ carboxy-7 lic acid which is subsequently reacted with the dicarboxy-8 lic acid reactant.
9 U.S. 4,173,540 discloses the reaction of poly-isobutenyl succinic anhydride with polyamines in a molar 11 ratio of 2.0 to 2.5 moles of anhydride per mole of poly-12 amine to provide a diimide dispersant, however, such 13 products will not meet the requirements for both gasoline 14 and diesel engine formulations.
U.S. 3,401,118 discloses reacting tetraethylene 16 pentamine first with polyisobutenyl succinic anhydride 17 (PIBSA) derived from 850-1200 ~n polyisobutylene and then 18 reacting this intermediate with PIBSA derived from poly-19 isobutylene of 400-750 ~n; the 400 ~n corresponding to 29 carbon atoms.
21 The present invention distinguishes from these 22 references in requiring a particular reaction sequence 23 characterized by the use of a dicarboxylic acid anhydride 24 in the final step and an overall mole ratio of anhydride to polyamine within a relatively narrow and critically defined 26 range. These parameters have been found essential to pro-27 vide lubricating oil compositions which give demonstrated 28 performance values in engine tests required to qualify for 29 the highest grade service classifications for both gasoline and diesel engine lubricating oils. The reaction sequence 31 is particularly critical; thus products prepared in a 32 simultaneous reaction technique will not meet the objectives 33 of this invention.
34 In accordance with this invention, there are provided lubricating oil compositions exhibiting improved 36 dispersancy in both gasoline and diesel engines comprising 37 a major amount of lubricating oil and an effective amount 1 of a polyalkenyl succinimide dispersant, said dispersant 2 being prepared in a two-step sequential process comprising 3 (a) ~irst reacting a polyalkenyl succinic anhydride, the 4 polyalkenyl being a polymer of a C3 or C4 olefin,and an alkylene polyamine of the formula H2N(CH2)n(NH(C~2)n)mNH2, 6 wherein n is 2 or 3 and m i9 0 to l0 in a molar ratio of 7 about l.0 to 2.2 moles of succinic anhydride per mole o~
8 polyamine, and (b) reacting the product of step (a) with 9 a di-carboxylic acid anhydride selected from the group consisting of maleic anhydride, succinic anhydride and 11 Cl-Cl8, preferably C8-Cl8,alkenyl or alkyl succinic 12 anhydrides in sufficient molar proportion to provide a 13 diimide dispersant having a total mole ratio of about 14 2.3 to 3.0 moles of anhydride per mole of polyamine.
The polyalkenyl succinic anhydrides useful in 16 the present invention ~enerally comprise those whecein 17 the polyalkenyl group has a ~n (number average molecular 18 weight~ of about 700 to 5,000, preferably 900 to 2,000.
19 The methods of preparation are well known in the art, i.e., reaction of maleic anhydride with either the poly-21 olefin itsel~ or with a chlorinated polyolefin which in 22 either case provides the desired polyalkenyl succinic 23 anhydride. Polyisobutylene is preferred but other polymers 24 of C3 or C4 olefins such as polybutene-l and polypropylene are suitable includinq mixtures of such polyolefins.
26 Suitable alkylene polyamines are also well 27 known represented by the formula NH2(CH~)n(NH(CH2)n)mNH2, 28 wherein n is 2 to 3 and m is 0 to l0. Illustrative are 29 ethylene diamine, diethylene triamine, triethylene tetra.mine, tetraethylene pentamine, pentaethylene hexamine, and the 31 like. Preferred for use is tetraethylene pentamine or a 32 mixture of ethylene polyamines which apptroxima~es tetra-33 ethylene pentamine such as "DOW E-l00" (~a commercial 34 mixture available from Dow Chemical Company, Midland, Michigan).
36 The terms polyalkenyl succinimide dispersant 37 or diimide dispersant as used herein is meant to encompass 1 the co~pleted reaction product of the sequential process 2 and is intended to encompass compounds wherein the product 3 may have amide, amidine or salt linkages in addition to 4 the Lmide linkage which results from the reaction of the primary amino group and the anhydride moiety.
6 The third reactant used to prepare the dis-7 persants of the present invention encompasses maleic 8 anhydride, succinic anhydride or an alkenyl or alkyl 9 succinic anhydride having up to about 18 carbon atoms and preferably at least 8 carbon atoms. Particularly 1 advantageous results in terms of engine performance data 12 have been obtained with dodecenyl succinic anhydride and 13 maleic anhydride and the use of these materials, and the 14 dispersants produced thereby, represent particularly preferred embodiments.
16 In the present invention, both the reaction 1l sequence and the overall final mole ratio of total succinic 18 anhydride groups to polyamine in the finished product 19 have been found to be essential to meet the objective of passing both engine qualification tests for gasoline and 21 diesel lubricating oil formulations. The reaction sequence 22 requires a first step in the preparation of a polyiso-23 butenyl succinic anhydride~polyamine reaction product.
24 These are reacted in a mole ratio of about 1.0 to 2.2 moles of polyisobutenyl succinic anhydride per mole of 26 polyamine. After this reaction is complete, suf~icient 27 maleic anhydride, succinic anhydride or alkenyl succinic 28 anhydride is then reacted to provide a final overall 29 mole ratio in the finished dispersant of about 2.3 to 3.0, preferably 2.3 to 2.5, moles of anhydride per 31 mole of polyamine.
32 These reactions are carried out at conventional 33 temperatures of about 80C to 200C, more preferably 34 140C to 165C, using a conventional solvent media, such as a mineral lubricating oil solvent so that the final 36 product is in a convenient solution in lubricating oil 37 which is entirely compatible with a lubricatin~ oil base 38 stock. Suitable solvent oils are the same as the oils 1 used as a lubricating oil base stock and these generally 2 include lubricating oils having a viscosity (ASTM D-445) 3 of about 2 to qO, preferably 5 to 20,centistokes at 4 99C, with the primarily paraffinic mineral oils being particularly preferred, such as Solvent 150 Neutral.
6 Lubricating oil compositions are prepared 7 containing the dispersant of the present invention to-8 gether with conventional amounts of other additives to g provide their normal attendant func~ions such as viscosity index improvers, rust inhibitors, metal detergent addi-11 tives, antioxidants, and zinc dialkyldithiophosphates 12 anti-wear additives and these compositions meet the 13 objective of passing engine qualification tests for both 14 gasoline and diesel engine usage. For gasoline engine lube oils to meet the current "SF" designation of the 16 American Petroleum Institute, lubricating oil for~ulations 17 must equal or exceed certain values in the MS Sequence VD
18 Engine Test (~STM Special Publication 315). For dispersancy, 19 the significant values in this test are a minimum of 9.4 sludge, 6.7 piston skirt varnish and 6.6 average varnish.
21 The Sequence VD uses a 1980 Ford 2.3 liter 4-cylinder 22 engine and is a 192-hour test comprising the cyclic 23 operation at varying engine speeds and temperatures to 24 simulate "stop and go" city driving and moderate turnpi~e operation. The test is an established industry standard.
26 For diesel performance the Caterpillar l-H/2 27 test is the current standard to evaluate the effects of 28 a crankcase oil on ring sticking and piston deposits.
29 The t~st simulates high speed, moderately supercharged engine operation~ This test is also Federal Test Method 31 791-346 and is used to meet military specifications such 32 as MIL-L-21260B and industry specifications such as 33 SAE 183 and General Motors GM6146M. For the 1~-2 Test 34 WTD (Weighted Total Demerits) is the principal value and for a 240-hour test, the target is a value within or 36 below the 90-100 range. This is derived fro~ the published 37 specification value of WTD 140 for a 480-hour test. WTD

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1 is a cumulative rating based on observation of deposits 2 in the groove and land areas of the piston and lacquer 3 on piston skirts with all the specific evaluation being 4 rated accocding to their relative importance and the final WTD being calculated in accordance with the test 6 procedure.
7 The dispersants prepared according to the 8 invention can be incorporated in a wide variety of lubricants.
g They can be used in lubricating oil compositions, such as automotive crankcase lubricating oils, automatic 11 transmission fluids, etc. in effective amounts to provide 12 active ingredient concentrations in finished formulations 13 generally within the range of about 0.5 to 10 weight 14 percentr for example, 1 to 5 weight percent, preferably 1.5 to 3 weiqht percent, of the total composition. Con-16 ventionally, the dispersants are admixed with the lubricat-7 ing oils as dispersant solution concentrates which usually 18 contain up to about 50 percent weight of the active 19 ingredient additive compound dissolved in mineral oil, 20 preferably a mineral oil having an ASTM D-445 viscosity 21 of about 2 to 40, prefera~ly 5 ~o 20 centistokes at 22 99C. The lubricatinq oil includes not only hydrocarbon 23 oils of lubricating viscosity derived from petroleum but 24 also includes synthetic lubricating oils such as polyethylene 25 oils; alkyl esters of dicarboxylic acids, complex esters 26 of dicarboxylic acid, polyglycol and alcohol; alkyl 27 esters of carbonic or phosphoric acids; polysilicones;
28 fluorohydrocarbon oils; and mixtures or lubricating oils 29 and synthetic oils in any proportion, etc. The term "lubricating oil" for this disclosure includes all the 31 foregoing. The useful dispersan~ may be conveniently 32 dispersed as a concentrate of 10 to 80 weight percent, 33 preferably up to about 50 weight percent, of said dispersant 34 in 20 to 90 weight percent of mineral oil, e.g., Solvent lS0 35 Neutral oil with or without other additives being present 36 and such concentrates are a further embodiment of this 37 invention.

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1 As noted above, such lubricating oil compositions 2 containing the dispersants of the present invention will 3 also contain other well-known additives such as the zinc 4 dialkyl (C3-Cg)dithiPhsphate anti-wear inhibitors, generally present in amounts of about l to S weight 6 percent. Useful detergents include the oil-soluble 7 normal basic or over-based metal, e.g., calcium, magnesium, 8 barium, etc., salts of petroleum naphthenic acids, petrol-9 eum sulfonic acids, alkyl benzene sulfonic acids, oil-soluble fa~ty acids, alkyl salicylic acids, alkylene 11 bis-phenols and hydrolyzed phosphosulfurized polyolefins.
12 Typical amounts are from l to 7 weight percent with the 13 ~D or diesel oils usually containing slightly more of 14 this metal detergent additive. Preferred detergents are the calcium and magnesium normal or overbased phenates, 16 sulfurized phenates or sulfonates. Diesel lubricating 17 oils preferably contain 4-6 percent of this additive.
18 Oxidation inhibitors include hindered phenols, 19 e.g., 2.6-ditertbutyl-para-cresol, amines, sulfurized phenols and alkyl phenothiazines usually present in 21 amounts of from 0.001 to l weight percent.
2~ Pour point depressants which may be present in 23 amounts of from 0.0l to 1 weight percent include wax 24 alkylated aromatic hydrocarbons, olefin polymers and copolymers, acrylate and methacrylate polymers and copoly-26 mers-27 Viscosity index improvers which may vary from 28 about 1 to 15 weight percent depending on the viscosity 29 grade required include olefin polymers such as polybutene, ethylene-propylene copolymers, hydrogenated polymers and 31 copolymers and terpolymers of styrene with isoprene 32 and/or butadiene, polymers of alkyl acrylates or alkyl 33 methacrylates, copolymers of alkyl methacrylates with N-34 vinyl pyrrolidone or dimethylaminoalkyl methacryla~e, post-grafted polymers of ethylene propylene with an 36 active monomer such as maleic anhydride which may be 37 further reacted with an alcohol or an alkylene polyamine, 1 styrene/maleic anhydride polymers post-~reated with 2 alcohols and amines, etc.
3 Rust inhibition activity can be provided by 4 about 0.01 to 1 weight percent of the afore-mentioned metal dihydrocarbyl dithiophosphates and the corresponding 6 precursor esters,phosphosulfurized pinenes, sulfurized 7 olefins and hydrocarbons, sulfurized fatty esters and 8 sulfurized alkyl phenols. Preferred are the zinc dl-g hydrocarbyl dithiophosphates which are salts of dihydro-carbyl esters of dithiophosphoric acids.
11 Other additives include effective amounts of 12 the fuel economy additives or friction reducing additives 13 such as the dimer acid esters, as disclosed in U.S.
14 4,105,571 to Shaub et al, which are present in amounts of about 1 to 5 weight percent with esters of dimerized 16 linoleic acid and diethylene glycol being a preferred 17 material. Glycerol oleates are another example of fuel 18 economyadditives and these are usually present in very 19 small amounts,such as 0.0S to 0.2 weight percent based on the weight of the formulated oil.
21 This invention is further illustrated by the 22 following examples which are not to be considered as 23 limitative of its scope.
24 Example 1 1500 grams of PIBSA (polyisobutenyl succinic 28 anhydride,~n=1300, Sap. No. 103) and 170 grams of an 27 ethylene polyamine mixture ("Dow E-100", available from 28 Dow Chemical Company, which approximates tetraethylene 29 pentamine)were reacted in solution in 808 grams of Sol-vent 150 Neutral, a paraffinic mineral oil, at 160C for 31 3 hours. The mole ratio of succinic anhydride to poly-32 amine was 1.4:1. Thereafter was added 225 grams of 33 dodecenyl succinic anhydride which provided a final mole 34 ratio of 2.4 moles of anhydride per mole of polyamine and this was reacted for 2 ~ours at 16~C. Af';er filtra-36 tion, the product analyzed at 1.83 percent N.

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1 Example 2 2 320 grams of the inital PIBSA/polyamine product 3 of Example 1 being the same but having a mole ratio of 4 2.1 mole of succinic anhydride per mole of polyamine was reacted with 6.0 grams of dodecenyl succinic anhydride 6 in Solvent 150 Neutral at 160C for 2 hours to provide a 7 product having a final mole ratio of 2.4 moles of anhydride 8 per mole of polyamine. The product analyzed for 1.50 g percent N.
Exam~le 3 11 Example 2 was repeated except that 2.2 grams 12 Of maleic anhydride was used to provide a product having 13 a final mole ratio of 2.4 moles of anhydride per mole of 14 polyamine. The product analyzed for 1.53 percent N.
Example 4 16 The product of Example 3 was included as the 17 dispersant at a concentration of 3.6 weight percent 18 active ingredient in a formulated SAE lOW40 lubricating 19 oil composition and subjected to the ASTM Sequence V-D
engine test for gasoline engines. The formulation also 21 contained conventional amounts of overbased sulfonate, 22 zinc dialkyl dithiophosphate, antioxidant, olefin copolymer 23 viscosity index improver, rust inhibitor and anti-foam 24 additive. The results were as follows:
Sludge = 9.51; piston skirt varnish = 7.06 26 varnish = 6.92. These results exceed the API "SF" minimum 27 values of 9.4 sludge; 6.7 piston skirt varnish and 6.6 28 varnish and therefore indicate the material is a commercial-29 ly useful dispersant.
Example 5 31 The products of Example 2 and Example 3 were 32 included in a lOW30 quali~y ~D (diesel) lubricating oil 33 formulations as the dispersant at 2.5 weight percent 34 active ingredient concentration and the oil was evaluated for diesel dispersancy performance in the Caterpillac 1-36 H/2 test. The formulation also contained olefin copolymer 37 V.I. improver to provide the lOW30 viscosity grade, 3.1 1 wt. ~ of a mixture of overbased and normal metal phenates, 2 1.5 weight percent of zinc dialkyl dithiophosphate anti-3 wear additive, and very small proportions of a~ti-oxidant 4 (0.3%) and anti-foamant (0.23).
The results for this diesel engine test are 6 given below:
7 240 Hour Caterpillar l-H/2 Test 8 ~ormulation TGF2 WTD3 g Data Basel 16.6 189.1 10 Example 3 14 66 t1 Example 2 11 98 12 Comparison4 1 183 13 lBase - These data are an average data base used for 14 comparison in evaluating new diesel oils and are an average of 25 engine tests of conventional formulations.
16 2TGF - Top groove fill, percent deposits in groove.
17 3WTD - Weighted total demerits.
18 4Comparison - The same formulation was tested using as 19 the dispersant a conventional polyisobutenyl succinic anhydride (Mn=900) - ethylene polyamine (DOW E-100) 21 reaction product dispersant where the anhydride to amine 22 mole ratio was 1.3 to 1.
23 Example 6 (Comparison) 24 The critical nature of the final ratio of anhydride to polyamine was further demonstrated with 2~ additional Caterpillar 1-~/2 tests. In 11 tests usinq 27 products similar to Examples 3 and 4 but having final 28 mole ratios varying between 1.3 and 2.0, an average WTD
29 value of 163 was obtained. Similarly, for an average of four engine tests were the final mole ratio was 2.1 to 31 2.2, an average value of 128 WTD was obtained.

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A lubricating oil composition exhibiting improved dispersancy in both gasoline and diesel engines comprising a major amount of lubricating oil and an effective amount of a dispersant, said dispersant being prepared in a sequential process comprising the steps of:
(a) in a first step reacting an oil-soluble polyolefin succinic anhydride, the olefin being a C3 or C4 olefin, with an alkylene polyamine of the formula H2N(CH2)n-(NH(CH2)n)mNH2 wherein n is 2 or 3 and m is 0 to 10, in a molar ratio of about 1.0 to 2.2 moles of polyolefin succinic an-hydride per mole of polyamine, and (b) reacting the product of step (a) with a dicarboxylic acid anhydride selected from the group consisting of maleic anhydride, succinic anhydride and C1-C18 alkenyl or alkyl succinic anhydride in sufficient molar proportions to provide a total mole ratio of about 2.3 to 3.0 moles of anhydride compounds per mole of polyamine.

2. The composition of claim 1 wherein the polyolefin is polyisobutylene of Mn 900 to 2,000.

3. The composition of claims 1 or 2 wherein the polyamine is an ethylene polyamine.

4. The composition of claims 1 or 2 wherein the dicarboxylic acid anhydride is maleic anhydride.

5. The composition of claims 1 or 2 wherein said dicarboxylic acid anhydride is dodecenyl succinic anhydride.

6. The composition of claims 1 or 2 wherein said total mole ratio is 2.3 to 2.5 to 1.

7. The composition of claims 1 or 2 wherein there is present 0.5 to 10 weight percent of the dispersant.

8. The composition of claims 1 or 2 further com-prising a metal detergent additive in an amount of from about 1 to 7 weight percent, a zinc dialkyl dithiophosphate anti-wear additive, 0.001 to 1 weight percent of an anti-oxidant, and 1 to 15 weight percent of a viscosity index improver.

9. The composition of claims 1 or 2 which is a diesel lubricating oil composition characterized by the presence of about 4 to 6 weight percent of normal or basic metal phenates, sulfurized phenate or sulfonate oil-soluble detergent additive or a mixture of said additives.

10. The composition of claim 1 which is in the form of a lubricating oil solution concentrate, said con-centrate containing 20 to 80 weight percent of said dis-persant.

11. A process for preparing a dispersant exhibiting improved dispersancy in both gasoline and diesel engine lubricating oil compositions, said dispersant being prepared in a sequential process comprising the steps of:
(a) in a first step reacting an oil-soluble polyolefin succinic anhydride, the olefin being a C3 or C4 olefin with an alkylene polyamine of the formula H2N(CH2)n-(NH(CH2)n)mNH2 wherein n is 2 or 3 and m is 0 to 10, in a molar ratio of about 1.0 to 2.2 moles of polyolefin succinic anhydride per mole of polyamine, and (b) reacting the product of step (a) with a dicarboxylic acid anhydride selected from the group consisting of maleic anhydride, succinic anhydride and C1-C18 alkenyl or alkyl succinic anhydride in sufficient molar proportions to provide a total mole ratio of about 2.3 to 3.0 moles of anhydride compounds per mole of polyamine.

12. The process of claim 11 wherein the poly-olefin is polyisobutylene of Mn 900 to 2,000, the polyamine is an ethylene polyamine, and the dicarboxylic acid anhydride is maleic anhydride.