Friction modifier system

Abstract

The present disclosure describes a lubricant additive. The additive is a friction modifier, and the friction modifier comprises a molybdenum-containing compound and a tertiary amine-containing composition having the following structure (I): wherein each R 1 and R 5 are each independently a straight-chain or branched-chain monovalent hydrocarbon group having from one to about twenty carbon atoms, wherein each R 2 、R 3 and R 4 are each independently hydrogen, a straight-chain or branched-chain monovalent hydrocarbon group having from one to about twenty carbon atoms, each m is independently from 0 to 4, each p is independently from 0 to 4, for each cyclic moiety, m + p is from 2 to 4, and each n is independently from 1 to 6.

Description

Technical Field

[0001] The present disclosure relates to lubricating oil additives and lubricating oil compositions containing the lubricating oil additives. More specifically, the present disclosure describes friction modifier compositions that can improve fuel efficiency. Background Art

[0002] To reduce energy losses due to friction, lubricant additives such as friction modifiers, anti-wear agents, and antioxidants (the latter often extend the action of the additives mentioned above) can be blended into engine oils.

[0003] In addition, to reduce hydrodynamic friction in the pistons / cylinders of an engine, the viscosity of the engine oil is reduced. This increases the importance of friction modifiers counteracting the new boundary layer regime. Therefore, to improve fuel economy, the interaction between oil viscosity and various friction modifiers has been closely studied. Summary of the Invention

[0004] In one aspect, there is provided a lubricating oil composition comprising: a) a major amount of a base oil; and b) a minor amount of a synergistic friction modifier composition, the synergistic friction modifier composition comprising: i) a molybdenum-containing compound; and ii) a tertiary amine-containing compound having the following structure:

[0005]

[0006] wherein each R 1 and R 5 are each independently a straight-chain or branched-chain monovalent hydrocarbon group having from one to about twenty carbon atoms, wherein each R 2 , R 3 and R 4 are each independently hydrogen, a straight-chain or branched-chain monovalent hydrocarbon group having from one to about twenty carbon atoms, each m is independently from 0 to 4, each p is independently from 0 to 4, for each cyclic moiety, m + p is from 2 to 4, and each n is independently 1 and 6.

[0007] The number of carbon atoms in the hydrocarbon group can have a great influence on the oil solubility of the molecule. Therefore, the number of carbon atoms in the hydrocarbon group should be a number sufficient to render the friction modifier oil-soluble.

[0008] In another aspect, there is provided a method of improving friction, the method comprising lubricating an engine with a lubricating oil comprising: a) a major amount of a base oil; and b) a minor amount of a synergistic friction modifier composition, the synergistic friction modifier composition comprising: i) a molybdenum-containing compound; and ii) a tertiary amine-containing compound having the following structure:

[0009]

[0010] Wherein each R 1 and R 5 is independently a straight-chain or branched-chain monovalent hydrocarbyl group having from one to about twenty carbon atoms, wherein each R 2 , R 3 and R 4 is independently hydrogen, a straight-chain or branched-chain monovalent hydrocarbyl group having from one to about twenty carbon atoms, each m is independently from 0 to 4, each p is independently from 0 to 4, for each cyclic moiety, m + p is from 2 to 4, and each n is independently from 1 to 6.

[0011] In yet another aspect, there is provided a lubricating oil composition comprising: a) a major amount of a base oil; b) a molybdenum-containing compound; and c) a product of the reaction comprising: i) a hydrocarbyl-substituted succinic anhydride represented by the following structure:

[0012]

[0013] wherein R 6 is a straight-chain or branched-chain monovalent hydrocarbyl group having from one to about twenty carbon atoms; and ii) a cyclic polyamine represented by the following structure:

[0014]

[0015] wherein R 7 is hydrogen or a straight-chain or branched-chain monovalent hydrocarbyl group having from one to about twenty carbon atoms, m is from 0 to 4, p is from 0 to 4, m + p is from 2 to 4, and n is from 1 to 6; and

[0016] wherein the ratio of the hydrocarbyl-substituted succinic anhydride to the cyclic polyamine is from about 1.5:1 to about 1.6:1. Detailed Description

[0017] Definition

[0018] The term "hydrocarbyl" refers to a chemical group or moiety derived from a hydrocarbon (including saturated and unsaturated hydrocarbons). Examples of hydrocarbyl groups include alkenyl, alkyl, polyalkenyl, polyalkyl, phenyl, and the like.

[0019] As used herein, the terms 'oil-soluble' or 'oil-dispersible' do not necessarily mean that a compound or additive is soluble, dissolvable, miscible, or capable of being suspended in oil in all proportions. However, these do mean, for example, that they are soluble in or stably dispersible in oil to an extent sufficient to perform their intended function in the environment in which the oil is used. Additionally, if desired, the incorporation of additional additives may also permit the incorporation of higher levels of a particular additive.

[0020] It should be understood that when combinations, subsets, groups, etc. of elements are disclosed (e.g., combinations of components in a composition, or combinations of steps in a method), each and every individual and collective combination and permutation of these elements is specifically contemplated and described herein, even though specific mention of each may not be explicitly disclosed.

[0021] The present invention relates to an additive composition useful as a friction modifier in lubricating oils. The friction modifier of the present invention comprises at least two synergistic components. The first component comprises one or more products resulting from the reaction of a hydrocarbyl-substituted succinic anhydride and a cyclic polyamine. The product is a tertiary amine-containing compound. The second component is a molybdenum-containing compound.

[0022] Tertiary amine compound

[0023] The first component of the friction modifier composition can be prepared by any known compatible method, such as those described in, for example, U.S. Patent Publication No. 20180034635 and U.S. Patent No. 7,091,306, which U.S. Patent Publication and U.S. Patent are hereby incorporated by reference.

[0024] The reaction can be carried out under various conditions. Generally, the hydrocarbyl-substituted succinic anhydride is reacted with the cyclic polyamine at a temperature of about 130 °C to 220 °C (e.g., 140 °C to 200 °C, 145 °C to 175 °C, etc.). More preferably, the temperature can be in the range of about 160 °C to 215 °C. Generally, the imidization step can be carried out at a lower temperature (e.g., 150 °C to 170 °C), while a higher temperature (e.g., 200 °C to 220 °C) may be required to complete the amidation step.

[0025] The reaction can be carried out under an inert atmosphere, such as nitrogen or argon. Generally, a suitable molar feed of the hydrocarbyl-substituted succinic anhydride to the cyclic polyamine is about 1.4:1 to about 1.7:1, more preferably about 1.5:1 to about 1.6:1. In some embodiments, it may be desirable for the charge mole ratio (CMR) of the hydrocarbyl-substituted succinic anhydride to the cyclic polyamine to be about 1.55:1 or slightly higher in order to react with any unreacted secondary amine. It is believed that secondary amines are more aggressive towards seals. The feed molar ratio is important because too much hydrocarbyl-substituted succinic anhydride can produce a monoamide / acid structure, while too little can produce a mono-succinimide product containing secondary amine. In some embodiments, the reaction can be carried out with a mixture of hydrocarbyl-substituted succinic anhydrides having different hydrocarbyl groups.

[0026] In some embodiments, the reaction can be carried out in multiple steps, where the total CMR of the hydrocarbyl-substituted succinic anhydride and the cyclic polyamine or cyclic polyamine product is from about 1.4:1 to about 1.7:1, more preferably from about 1.5:1 to about 1.6:1. For example, the first step may involve reacting the hydrocarbyl-substituted succinic anhydride with the cyclic polyamine in a feed molar ratio of 1:1 to form an imide structure. In the second step, the imide structure is reacted with the hydrocarbyl-substituted succinic anhydride in a feed molar ratio of about 0.5 (succinic anhydride:imide product). The total CMR of the two steps is 1.5:1. The hydrocarbyl-substituted succinic anhydride in the first step and the hydrocarbyl-substituted succinic anhydride in the second step may be the same or different in the hydrocarbyl group.

[0027] According to one embodiment, the hydrocarbyl-substituted succinic anhydride is given by Structure I:

[0028]

[0029] where R 6 is a straight-chain or branched-chain monovalent hydrocarbyl group having from one to about twenty carbon atoms, such as from ten to twenty carbon atoms, from twelve to twenty carbon atoms, and from fourteen to twenty carbon atoms. In some embodiments, the average carbon number is about 14 or higher. R 6 can be cyclic or acyclic. In some embodiments, R 6 is saturated. In other embodiments, R 6 is unsaturated.

[0030] The exact structure of the hydrocarbyl group can depend on many factors. Solubility in oil is an important consideration. Generally, longer hydrocarbyl groups have greater solubility in oil.

[0031] Hydrocarbyl-substituted succinic anhydrides are readily commercially available. For example, alkenyl succinic anhydrides are widely used in paper sizing. In contrast, the hydrocarbyl-substituted succinic anhydrides of the present invention can be synthesized by well-established methods. One conventional synthesis involves reacting maleic anhydride with an olefin at an elevated temperature (about 200 °C).

[0032] According to one embodiment, the cyclic polyamine is represented by Structure II:

[0033]

[0034] where R 7 is hydrogen or a straight-chain or branched-chain monovalent hydrocarbyl group having from one to about twenty carbon atoms, m is 0 to 4, p is 0 to 4, where m + p is 2 to 4, and n is 1 to 6. R 7 can be cyclic or acyclic. In some embodiments, R 7 is saturated. In other embodiments, R 7is unsaturated. The cyclic polyamine serves as a source of basic tertiary amines.

[0035] Many of the polyamines suitable for use in the present invention are commercially available, and other polyamines can be prepared by methods well known in the art. For example, methods for preparing amines and their reactions are detailed in Sidgewick's “The Organic Chemistry of Nitrogen”, Clarendon Press, Oxford, 1966; Noller's “Chemistry of Organic Compounds”, Saunders, Philadelphia, 2nd Edition, 1957; and Kirk - Othmer's “Encyclopedia of Chemical Technology”, 2nd Edition, particularly Volume 2, pages 99 - 116.

[0036] Suitable examples of cyclic polyamines include, for example, aminoethylpiperazine, aminopropylpiperazine, aminobutylpiperazine, aminoethyldiazepane, aminoethyldiazocane, their suitable derivatives, and the like.

[0037] One class of reaction products can be represented by Structure III:

[0038]

[0039] where each R 1 and R 5 are each independently a straight - chain or branched - chain monovalent hydrocarbon group having from one to about twenty carbon atoms, where each R 2 、R 3 and R 4 are each independently hydrogen, a straight - chain or branched - chain monovalent hydrocarbon group having from one to about twenty carbon atoms, each m is independently from 0 to 4, each p is independently from 0 to 4, for each cyclic moiety, m + p is from 2 to 4, and each n is independently from 1 to 6.

[0040] Molybdenum compound

[0041] The molybdenum - containing compound is an organomolybdenum compound containing molybdenum, carbon, and hydrogen atoms, but may also contain sulfur, phosphorus, nitrogen, and / or oxygen atoms. Suitable organomolybdenum compounds include molybdenum dithiocarbamate, molybdenum dithiophosphate, and various organomolybdenum complexes (such as molybdenum carboxylates, molybdenum esters, molybdenum amines, molybdenum amides), which can be obtained by reacting molybdenum oxide or ammonium molybdate with fats, glycerol esters, or fatty acids or fatty acid derivatives (e.g., esters, amines, amides). The term “fat” means a carbon chain having 8 to 22 carbon atoms, usually a straight carbon chain.

[0042] Suitable molybdenum dithiocarbamates include any molybdenum dithiocarbamate that can be used as an additive in lubricating oils. One class of molybdenum dithiocarbamates for use herein is represented by Structure IV:

[0043]

[0044]

[0045] wherein R 8 、R 9 、R 10 and R 11 are each independently hydrogen or a hydrocarbyl group, including, for example, alkyl, alkenyl, aryl, cycloalkyl, and cycloalkenyl, and X 1 、X 2 、X 3 and X 4 are each independently sulfur or oxygen. In some embodiments, each R 8 、R 9 、R 10 and R 11 independently contains 6 to 18 carbon atoms.

[0046] Suitable alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, tert-pentyl, hexyl, sec-hexyl, heptyl, sec-heptyl, octyl, 2-ethylhexyl, sec-octyl, nonyl, sec-nonyl, decyl, sec-decyl, undecyl, sec-undecyl, dodecyl, sec-dodecyl, tridecyl, isotridecyl, sec-tridecyl, tetradecyl, sec-tetradecyl, hexadecyl, sec-hexadecyl, stearyl, eicosyl, docosyl, tetracosyl, triacontyl, 2-butyloctyl, 2-butyl decyl, 2-hexyloctyl, 2-hexyldecyl, 2-octyldecyl, 2-hexyldodecyl, 2-octyldodecyl, 2-decyltetradecyl, 2-dodecylhexadecyl, 2-hexadecylvinyloctadecyl, 2-tetradecylvinyloctadecyl, monomethyl-branched isostearyl, and the like.

[0047] Suitable alkenyl groups include, but are not limited to, vinyl, allyl, propenyl, butenyl, isobutenyl, pentenyl, isopentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, oleyl, and the like.

[0048] Suitable aryl groups include, but are not limited to, phenyl, tolyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, diphenylmethyl, triphenylmethyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, biphenyl, benzylphenyl, styrenated phenyl, p-cumylphenyl, α-naphthyl, β-naphthyl, and the like.

[0049] Suitable cycloalkyl and cycloalkenyl groups include, but are not limited to, cyclopentyl, cyclohexyl, cycloheptyl, methylcyclopentyl, methylcyclohexyl, methylcycloheptyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, methylcyclopentenyl, methylcyclohexenyl, methylcycloheptenyl, and the like.

[0050] In Structure IV, X 1 to X 4 are independently selected from a sulfur or oxygen atom, and X 1 to X 4 can all be sulfur atoms or oxygen atoms, or a mixture of sulfur atoms and oxygen atoms. Considering the balance between friction reduction effect and corrosiveness, the molar ratio (number ratio) of one or more sulfur atoms to one or more oxygen atoms should be particularly preferably in the range of about 1 / 3 to about 3 / 1.

[0051] Some of the oil-soluble or oil-dispersible and oil-stable molybdenum compounds having Structure IV are commercially available. For example, a product in which X 1 and X 2 are O, X 3 and X 4 are S and in which R 8 to R 11 are C 13 H 27 aliphatic hydrocarbon groups and in which molybdenum is in the oxidation state V is sold by R.T. Vanderbilt Company Inc. (Norwalk, Conn., USA) under the trademarks 807 and 822 as antioxidants and friction reduction additives. These molybdenum compounds can be prepared by the method described in U.S. Patent No. 3,356,702, in which the n MoO3 is converted to a soluble molybdate by dissolving MoO3 in an alkali metal hydroxide solution and neutralized by adding an acid and then adding a secondary amine and carbon disulfide. In another aspect, molybdenum compounds of Structure IV in which X 1 to X 4 are O or S can be prepared by a variety of methods known in the art, such as, for example, those described in U.S. Patent Nos. 4,098,705 and 5,631,213.

[0052] Generally, molybdenum sulfide dithiocarbamate represented by Structure IV can be prepared by reacting molybdenum trioxide or molybdate with an alkali metal sulfide or an alkali metal hydrosulfide and then adding carbon disulfide and a secondary amine to the reaction mixture and reacting the resulting mixture at an appropriate temperature. To prepare an asymmetric molybdenum sulfide dithiocarbamate, it is sufficient to use a secondary amine having different hydrocarbon groups or two or more different secondary amines in the above process. Symmetric molybdenum sulfide dithiocarbamate can also be prepared in a similar manner, but only one secondary amine is used.

[0053] Examples of suitable molybdenum dithiocarbamate compounds include, but are not limited to, molybdenum sulfide diethyldithiocarbamate, molybdenum sulfide dipropyldithiocarbamate, molybdenum sulfide dibutyldithiocarbamate, molybdenum sulfide dipentyldithiocarbamate, molybdenum sulfide dihexyldithiocarbamate, molybdenum sulfide dioctyldithiocarbamate, molybdenum sulfide didecyldithiocarbamate, molybdenum sulfide bis-dodecyldithiocarbamate, molybdenum sulfide bis-tridecyldithiocarbamate, molybdenum sulfide bis-(butylphenyl)dithiocarbamate, molybdenum sulfide bis-(nonylphenyl)dithiocarbamate, molybdenum sulfoxide diethyldithiocarbamate, molybdenum sulfoxide dipropyldithiocarbamate, molybdenum sulfoxide dibutyldithiocarbamate, molybdenum sulfoxide dipentyldithiocarbamate, molybdenum sulfoxide dihexyldithiocarbamate, molybdenum sulfoxide dioctyldithiocarbamate, molybdenum sulfoxide didecyldithiocarbamate, molybdenum sulfoxide bis-dodecyldithiocarbamate, molybdenum sulfoxide bis-tridecyldithiocarbamate, molybdenum sulfoxide bis-(butylphenyl)dithiocarbamate, molybdenum sulfoxide bis-(nonylphenyl)dithiocarbamate, wherein all alkyl groups can be straight-chain or branched, etc., and mixtures thereof.

[0054] Trinuclear dialkyldithiocarbamate molybdenum compounds are also known in the art, as taught by U.S. Patent Nos. 5,888,945 and 6,010,987, which are incorporated herein by reference. There are trinuclear molybdenum compounds, preferably those having the formulas Mo3S4(dtc)4 and Mo3S7(dtc)4 and mixtures thereof (where dtc represents a diorganodithiocarbamate ligand independently selected containing an independently selected organic group, and wherein the ligand has a sufficient number of carbon atoms in all organic groups of the ligands of the compound) such that the compound is soluble or dispersible in a lubricating oil.

[0055] Molybdate esters prepared by the methods disclosed in US 4,889,647 and US 6,806,241 B2. A commercial example is Additive 855, which is manufactured by R.T.Vanderbilt Company, Inc.

[0056] Molybdenum dithiophosphate (MoDTP) is an organomolybdenum compound represented by the following structure V:

[0057]

[0058] wherein R 12 、R 13 、R 14 and R 15 are each independently a straight-chain or branched alkyl group having 4 to 18 carbon atoms (e.g., 8 to 13 carbon atoms).

[0059] Molybdenum carboxylates are described in U.S. Patent RE 38,929 and U.S. Patent No. 6,174,842 and are hereby incorporated by reference. Molybdenum carboxylates can be derived from any oil-soluble carboxylic acid. Typical carboxylic acids include naphthenic acid, 2-ethylhexanoic acid, and linolenic acid. Suitable examples of molybdenum compounds include commercial materials sold under trade names such as 822, M A, 2000, 807, and 855T from R.T. Vanderbilt Co., Ltd. and Sakura-Lube TM S-165, S-200, S-300, S-310G, S-525, S-600, S-700, and S-710 available from Adeka Corporation, as well as mixtures thereof. Suitable molybdenum components are described in U.S. Patent Nos. 5,650,381, RE 37,363 E1, RE 38,929 E1, and RE 40,595 E1, which are hereby incorporated by reference in their entirety.

[0060] Ammonium molybdate is prepared by an acid-base reaction of an acidic molybdenum source such as molybdenum trioxide, molybdic acid, and ammonium molybdate and ammonium thiomolybdate with an oil-soluble amine and optionally in the presence of a sulfur source such as sulfur, inorganic sulfides and polysulfides, and carbon disulfide. Preferred amine compounds are polyamine dispersants, which are commonly used in engine oil compositions. Examples of such dispersants are succinimides and Mannich type. References for these preparations are U.S. Patent Nos. 4,259,194, 4,259,195, 4,265,773, 4,265,843, 4,727,387, 4,283,295, and 4,285,822.

[0061] In one embodiment, the molybdenum amine is a molybdenum-succinimide complex. Suitable molybdenum-succinimide complexes are described, for example, in U.S. Patent No. 8,076,275. These complexes are prepared by a process that includes reacting an acidic molybdenum compound with an alkyl or alkenyl succinimide of a polyamine of Structure VI or VII or a mixture thereof:

[0062]

[0063]

[0064] wherein R is C 24 to C 350 (e.g., C 70 to C 128 ) alkyl or alkenyl; R' is a straight or branched chain alkylene having 2 to 3 carbon atoms; x is 1 to 11; and y is 1 to 10.

[0065] The molybdenum compound used to prepare the molybdenum-succinimide complex is an acidic molybdenum compound or a salt of an acidic molybdenum compound. "Acidic" means that the molybdenum compound will react with a basic nitrogen compound, as measured by ASTM D664 or D2896. Generally, the acidic molybdenum compound is hexavalent. Representative examples of suitable molybdenum compounds include molybdenum trioxide, molybdic acid, ammonium molybdate, sodium molybdate, potassium molybdate, and other alkali metal molybdates and other molybdenum salts, such as hydrogen salts (e.g., sodium hydrogen molybdate), MoOCl4, MoO2Br2, Mo2O3Cl6, etc.

[0066] The succinimides that can be used to prepare the molybdenum-succinimide complex are disclosed in many references and are well known in the art. Certain basic types of succinimides and related materials covered by the term "succinimide" are taught in U.S. Patent Nos. 3,172,892, 3,219,666, and 3,272,746. The term "succinimide" is understood in the art to include many of the amide, imide, and amidine substances that may also form. However, the major product is the succinimide, and this term has been generally accepted to mean the product of the reaction of an alkyl or alkenyl substituted succinic acid or anhydride with a nitrogen-containing compound. Preferred succinimides are those prepared by reacting a polyisobutenyl succinic anhydride having about 70 to 128 carbon atoms with a polyalkylene polyamine selected from triethylenetetramine, tetraethylenepentamine, and mixtures thereof.

[0067] In one embodiment, the molybdenum-containing compound is sulfur-free.

[0068] The molybdenum-succinimide complex can be post-treated with a sulfur source at a suitable pressure and a temperature not exceeding 120 °C to provide a molybdenum sulfide-succinimide complex. The sulfidation step can be carried out for a period of about 0.5 to 5 hours (e.g., 0.5 to 2 hours). Suitable sulfur sources include elemental sulfur, hydrogen sulfide, phosphorus pentasulfide, organic polysulfides of the formula R2S x (wherein R is a hydrocarbon group (e.g., C1 to C 10 alkyl) and x is at least 3), C1 to C 10 thiols, inorganic sulfides and polysulfides, thioacetamide, and thiourea.

[0069] Lubricating oil

[0070] When used as a lubricant additive, the tertiary amine compound of the present invention is generally present in the lubricating oil composition at a concentration in the range of about 0.001 wt% to about 20 wt% (including but not limited to 0.01 wt% to 5 wt%, 0.2 wt% to 4 wt%, 0.5 wt% to 3 wt%, 1 wt% to 2 wt%, etc.) based on the total weight of the lubricating oil composition.

[0071] When used as a lubricant additive, the molybdenum-containing compound of the present invention is generally present in the lubricating oil composition at a concentration in the range of about 50 to about 1500 ppm (including but not limited to 200 to 1400 ppm, 250 to 1250 ppm, 500 to 1000 ppm, 500 to 750 ppm, etc.).

[0072] The oil used as the base oil will be selected or blended according to the desired end use and the additives in the finished oil to obtain a lubricating oil composition of the desired grade, such as a lubricating oil composition having an American Petroleum Institute (API) viscosity grade of 0W, 0W-8, 0W-12, 0W-16, 0W-20, 0W-30, 0W-40, 0W-50, 0W-60, 5W, 5W-20, 5W-30, 5W-40, 5W-50, 5W-60, 10W, 10W-20, 10W-30, 10W-40, 10W-50, 15W, 15W-20, 15W-30, or 15W-40.

[0073] An oil of lubricating viscosity (sometimes referred to as a "base stock" or "base oil") is the main liquid component of a lubricant, and additives and possibly other oils are blended into the main liquid component, e.g., to produce a final lubricant (or lubricant composition). Base oils that can be used to prepare concentrates and that can be used to prepare lubricating oil compositions therefrom can be selected from natural (vegetable, animal, or mineral) lubricating oils and synthetic lubricating oils and mixtures thereof.

[0074] The definitions of base stocks and base oils in this disclosure are the same as those in Appendix E of API Publication 1509 ("API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils," December 2016). Using the test methods specified in Table E-1, Group I base stocks contain less than 90% saturates and / or greater than 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120. Using the test methods specified in Table E-1, Group II base stocks contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120. Using the test methods specified in Table E-1, Group III base stocks contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 120. Group IV base stocks are polyalphaolefins (PAOs). Group V base stocks include all other base stocks not included in Group I, Group II, Group III, or Group IV.

[0075] Natural oils include animal oils, vegetable oils (such as castor oil and lard), and mineral oils. Animal and vegetable oils with good thermal oxidation stability can be used. Among natural oils, mineral oils are preferred. Mineral oils vary widely in their crude oil sources, for example, in whether they are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils derived from coal or shale are also useful. Natural oils also vary in the methods used for their production and purification, for example, in their distillation range and whether they are straight-run, cracked, hydrorefined, or solvent-extracted.

[0076] Synthetic oils include hydrocarbon oils. Hydrocarbon oils include oils such as polymerized and interpolymerized olefins (e.g., polybutene, polypropylene, propylene-isobutene copolymers, ethylene-olefin copolymers, and ethylene-alpha-olefin copolymers). Polyalphaolefin (PAO) oil base stocks are commonly used synthetic hydrocarbon oils. For example, PAOs derived from C8 to C 14 olefins (such as C8, C 10 , C 12 , C 14 olefins or mixtures thereof) can be used.

[0077] Other useful fluids used as base oils include unconventional or non-conventional base stocks that have been processed (preferably catalytically) or synthesized to provide high-performance characteristics.

[0078] Unconventional or non-conventional base oils include one or more of the following: a mixture of one or more base oils derived from one or more gas-to-liquid (GTL) materials, and one or more isomerized / isodewaxed base oils derived from the following: natural wax or waxy feedstock, mineral oil and / or non-mineral oil waxy raw materials such as slack wax, natural wax and waxy raw materials such as gas oil, waxy fuel hydrocracker bottoms residue, waxy residual liquid, hydrocracked products, thermal cracked products, or other minerals, mineral oils, or even non-petroleum-derived waxy materials (such as waxy materials obtained from coal liquefaction or shale oil), and mixtures of such base oils. Other base oils include coal-to-liquid (CTL) products and alkyl-naphthalenes.

[0079] The base oils for the lubricating oil compositions of the present disclosure are any of the types of oils corresponding to API Group I, Group II, Group III, Group IV, and Group V oils and mixtures thereof (preferably API Group II, Group III, Group IV, and Group V oils and mixtures thereof, more preferably Group III to Group V base oils) because they have excellent volatility, stability, viscosity, and cleanliness characteristics.

[0080] Typically, the base oil will have a kinematic viscosity in the range of 1.5 to 35 mm 2 / s (e.g., 1.5 to 25 mm 2 / s, 2.0 to 20 mm 2 / s or 2.0 to 15 mm 2 / s) at 100 °C (ASTM D445).

[0081] The lubricating oil compositions of the present invention may also contain conventional lubricant additives for imparting auxiliary functions to obtain a finished lubricating oil composition in which these additives are dispersed or dissolved. For example, the lubricating oil composition can be blended with antioxidants, ashless dispersants, antiwear agents, detergents (such as metal detergents), rust inhibitors, defogging agents, demulsifiers, friction improvers, metal deactivators, pour point depressants, viscosity improvers, antifoaming agents, co-solvents, package compatibilizers, corrosion inhibitors, dyes, extreme pressure agents, etc. and mixtures thereof. A variety of additives are known and commercially available. These additives or their similar compounds can be used to prepare the lubricating oil compositions of the present invention by common blending procedures.

[0082] Each of the foregoing additives is used in a functionally effective amount for imparting the desired properties to the lubricant. Thus, for example, if the additive is an ashless dispersant, the functionally effective amount of such ashless dispersant will be an amount sufficient to impart the desired dispersancy properties to the lubricant. Generally, unless otherwise stated, the concentration of each of these additives in use can be in the range of about 0.001 wt% to about 20 wt%, such as about 0.01 wt% to about 10 wt%.

[0083] The following non-limiting examples illustrate the present invention. A brief description of how the examples were prepared is provided.

[0084] Examples

[0085] Comparative Example A

[0086] Comparative Example A is a baseline 0W-16 lubricating oil containing a total of 14.1 wt% of succinimide dispersant, calcium detergent, secondary ZnDTP, phenolic antioxidant, foam inhibitor, and polymethacrylate-based viscosity improver. Comparative Example A also contains 700 ppm of molybdenum from MoDTC.

[0087] Comparative Example B

[0088] Comparative Example B contains the baseline 0W-16 lubricating oil of Comparative Example A and 0.3 wt% of glyceryl monooleate.

[0089] Comparative Example C

[0090] Comparative Example C contains the lubricating oil of Comparative Example A, 0.3 wt% of glyceryl monooleate, and 700 ppm of molybdenum from MoDTC.

[0091] Comparative Example D

[0092] Comparative Example D contains the baseline 0W-16 lubricating oil of Comparative Example A, 0.3 wt% of C16 / 18 1,2-hydroxyalkane friction modifier, and 700 ppm of molybdenum from MoDTC.

[0093] Comparative Example E

[0094] Comparative Example E contains the baseline 0W-16 lubricating oil of Comparative Example A, 0.3 wt% of alkyldiamine friction modifier, and 700 ppm of molybdenum from MoDTC.

[0095] Comparative Example F

[0096] Comparative Example F contains the baseline 0W-16 lubricating oil of Comparative Example A and 0.3 wt% of branched C18 Reaction product of succinic anhydride and aminoethyl piperazine. The feed molar ratio (CMR) of succinic anhydride to aminoethyl piperazine is 1.6:1.

[0097] Example 1

[0098] Example 1 contains the baseline 0W-16 lubricating oil of Comparative Example A, 0.3 wt% of branched C 18 Reaction product of succinic anhydride and aminoethyl piperazine (the feed molar ratio of succinic anhydride to aminoethyl piperazine is 1.6:1) and 700 ppm of molybdenum from MoDTC.

[0099] Example 2

[0100] Example 2 contains the baseline 0W-16 lubricating oil of Comparative Example A, 0.1 wt% of branched C 18 Reaction product of succinic anhydride and aminoethyl piperazine (CMR of succinic anhydride to aminoethyl piperazine is 1.6:1) and 700 ppm of molybdenum from MoDTC.

[0101] Example 3

[0102] Example 3 contains the baseline 0W-16 lubricating oil of Comparative Example A, 1.0 wt% of branched C 18 Reaction product of succinic anhydride and aminoethyl piperazine (CMR of succinic anhydride to aminoethyl piperazine is 1.6:1) and 700 ppm of molybdenum from MoDTC.

[0103] MTM Friction Test

[0104] A micro-traction machine (MTM) was used to evaluate the friction properties. The MTM is a ball-on-disc friction machine that can measure the friction properties of lubricants under a wide range of sliding-rolling conditions by independently controlling the sliding and rolling speeds. The test specimens are a 19.05 mm diameter ball and a 46 mm diameter disc, which are made of 52100 steel with a hardness of 720-780 VPN.

[0105] All friction coefficients were measured after two hours of friction at an entrainment speed of 100 mm / s, a temperature of 60 °C, a load of 37 N (maximum Hertzian contact pressure of 1.02 GPa), and a 50% SRR (slip-roll ratio).

[0106] After two hours of friction, the friction coefficient was measured at an applied load of 37 N and a 50% SRR (slip-roll ratio), where the entrainment speed for Stribeck measurement started from 3000 mm / s and decreased to 2 mm / s, consisting of 36 data points. The results are shown in Table 1.

[0107] The final boundary friction results are provided based on the cumulative area calculated between entrainment velocities of 2 and 10 mm / s using the following formula:

[0108] Boundary Friction =

[0109] Σ((CoFi + CoFi+1) / 2) x (Log(Entrainment Velocityi+1) - Log(Entrainment Velocityi))

[0110] Table 1

[0111]

[0112] All documents described herein are incorporated herein by reference, including any priority documents and / or test procedures, provided they are not inconsistent with the present disclosure. As will be apparent from the foregoing general description and specific embodiments, while the forms of the present disclosure have been illustrated and described, various modifications may be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby.

[0113] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges starting from any lower limit can be combined with any upper limit to enumerate ranges not explicitly enumerated, and ranges starting from any lower limit can be combined with any other lower limit to enumerate ranges not explicitly enumerated, in the same way, ranges starting from any upper limit can be combined with any other upper limit to enumerate ranges not explicitly enumerated. Additionally, every point or single value between the endpoints of a range is included within the range, even if not explicitly enumerated. Thus, each point or single value can serve as its own lower or upper limit to be combined with any other point or single value or any other lower or upper limit to enumerate ranges not explicitly enumerated.

[0114] Likewise, the term "comprising" is considered synonymous with the term "including". Likewise, whenever a composition, element, or group of elements is preceded by the transitional phrase "comprising", it should be understood that we also contemplate the said composition or group of elements preceded by the transitional phrases "consisting essentially of", "consisting of", "selected from the group consisting of", or "is", and vice versa.

[0115] As used herein, the terms "a" and "the" are to be understood to cover both the plural and the singular.

[0116] Various terms have been defined above. If a term used in a claim is not defined above, it should be given the broadest definition that persons in the relevant art have given to that term as reflected in at least one printed publication or issued patent. In addition, all patents, test procedures, and other documents cited in this application are hereby incorporated by reference in their entirety, provided that such disclosure is not inconsistent with this application and is applicable in all jurisdictions that permit such incorporation.

[0117] The foregoing description has illustrated and described the present disclosure. Additionally, the present disclosure has been shown and described only in its preferred embodiments, but as mentioned above, it should be understood that the present disclosure is capable of being used in various other combinations, modifications, and environments, and can be varied or modified within the scope of the concepts as expressed herein that are commensurate with the above teachings and / or the skill or knowledge in the relevant art. While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure can be devised without departing from the basic scope thereof, and the scope of the present disclosure is determined by the appended claims.

[0118] It should be understood that when combinations, subsets, groups, etc. of elements are disclosed (e.g., combinations of components in a composition, or combinations of steps in a method), each and every one of the various individual and collective combinations and permutations of these elements are specifically contemplated and described herein, even though specific mention of each may not be explicitly disclosed.

[0119] The embodiments described above are further intended to explain the best mode known for practicing it and to enable other persons skilled in the art to utilize the present disclosure in such or other embodiments and with the various modifications required for a particular application or use. Accordingly, this description is not intended to limit the invention to the forms disclosed herein. Additionally, the appended claims are intended to be construed to include alternative embodiments.

Claims

1. A lubricating oil composition, the lubricating oil composition comprising: a) A major amount of a base oil; and b) A minor amount of a synergistic friction improver composition, the synergistic friction improver composition comprising: i) A molybdenum-containing compound; and ii) A tertiary amine-containing compound having the following structure: where each R 1 and R 5 is independently a straight-chain or branched-chain monovalent hydrocarbyl group having from 1 to 20 carbon atoms, where each R 2 、R 3 and R 4 is independently hydrogen, a straight-chain or branched-chain monovalent hydrocarbyl group having from 1 to 20 carbon atoms, each m is independently from 0 to 4, each p is independently from 0 to 4, for each cyclic moiety, m + p is from 2 to 4, and each n is independently from 1 to 6.

2. The lubricating oil composition according to claim 1, wherein the straight-chain or branched-chain monovalent hydrocarbon group is a branched C 12 to C 20 alkenyl.

3. The lubricating oil composition according to claim 1, wherein the straight-chain or branched-chain monovalent hydrocarbon group is a branched C 18 to C 20 alkenyl group.

4. The lubricating oil composition according to claim 1, wherein the tertiary amine-containing compound is present in an amount of 0.1% to 2% by weight based on the weight of the lubricating oil composition.

5. The lubricating oil composition according to claim 1, wherein the molybdenum-containing compound is molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum carboxylate, molybdenum ester, molybdenum amine or molybdenum amide.

6. The lubricating oil composition according to claim 5, wherein the molybdenum dithiocarbamate is given by the following structure: wherein R 8 , R 9 , R 10 and R 11 are each independently hydrogen or a hydrocarbon group, said hydrocarbon group including an alkyl group, an alkenyl group, an aryl group, a cycloalkyl group and a cycloalkenyl group, and X 1 , X 2 , X 3 and X 4 are each independently sulfur or oxygen.

7. The lubricating oil composition according to claim 1, wherein the molybdenum-containing compound is present in the lubricating oil composition at a concentration in the range of 50 to 1500 ppm.

8. A method of improving friction, the method comprising lubricating an engine with a lubricating oil, the lubricating oil comprising: a) A major amount of a base oil; and b) A minor amount of a synergistic friction improver composition, the synergistic friction improver composition comprising: i) A molybdenum-containing compound; and ii) A tertiary amine additive having the following structure: where each R 1 and R 5 is independently a straight-chain or branched-chain monovalent hydrocarbyl group having from 1 to 20 carbon atoms, where each R 2 , R 3 and R 4 is independently hydrogen, a straight-chain or branched-chain monovalent hydrocarbyl group having from 1 to 20 carbon atoms, each m is independently from 0 to 4, each p is independently from 0 to 4, for each cyclic moiety, m + p is from 2 to 4, and each n is independently from 1 to 6.

9. The method according to claim 8, wherein the linear or branched chain monovalent hydrocarbon group is a branched C 12 to C 20 alkenyl.

10. The method according to claim 8, wherein the straight-chain or branched-chain monovalent hydrocarbon group is a branched C 18 to C 20 alkenyl.

11. The method according to claim 8, wherein the tertiary amine additive is present in an amount of 0.1% to 2% by weight based on the weight of the lubricating oil composition.

12. The method according to claim 8, wherein the molybdenum-containing compound is molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum carboxylate, molybdenum ester, molybdenum amine or molybdenum amide.

13. The method according to claim 12, wherein the molybdenum dithiocarbamate is given by the following structure: wherein R 8 、R 9 、R 10 and R 11 are each independently hydrogen or a hydrocarbon group, said hydrocarbon group including alkyl, alkenyl, aryl, cycloalkyl and cycloalkenyl, and X 1 、X 2 、X 3 and X 4 are each independently sulfur or oxygen.

14. The method according to claim 8, wherein the molybdenum-containing compound is present in the lubricating oil composition at a concentration in the range of 50 to 1500 ppm.

15. A lubricating oil composition, the lubricating oil composition comprising: a) A major amount of a base oil; b) A molybdenum-containing compound; and c) The product of a reaction comprising: i) A hydrocarbyl-substituted succinic anhydride represented by the following structure: wherein R 6 is a straight-chain or branched-chain monovalent hydrocarbon group having from 1 to 20 carbon atoms; and ii) A cyclic polyamine represented by the following structure: wherein R 7 is hydrogen or a straight-chain or branched-chain monovalent hydrocarbon group having from 1 to 20 carbon atoms, m is from 0 to 4, p is from 0 to 4, m + p is from 2 to 4, and n is from 1 to 6; and wherein the molar ratio of the hydrocarbyl-substituted succinic anhydride to the cyclic polyamine is from 1.5:1 to 1.6:

1.

16. The lubricating oil composition according to claim 15, wherein the cyclic polyamine is aminoethyl piperazine, aminopropyl piperazine, aminobutyl piperazine, aminoethyl diazepane or aminoethyl diazocane.

17. The lubricating oil composition according to claim 15, wherein the molybdenum-containing compound is molybdenum dithiocarbamate, molybdenum dithiophosphate, molybdenum carboxylate, molybdenum ester, molybdenum amine or molybdenum amide.

18. The lubricating oil composition according to claim 17, wherein the molybdenum dithiocarbamate is given by the following structure: wherein R 8 , R 9 , R 10 and R 11 are each independently hydrogen or a hydrocarbon group, said hydrocarbon group including alkyl, alkenyl, aryl, cycloalkyl and cycloalkenyl, and X 1 , X 2 , X 3 and X 4 are each independently sulfur or oxygen.

19. The lubricating oil composition according to claim 15, wherein the molybdenum-containing compound is present in the lubricating oil composition at a concentration in the range of 50 to 1500 ppm.

20. The lubricating oil composition according to claim 18, wherein each R 8 , R 9 , R 10 and R 11 independently contains 6 to 18 carbon atoms.

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