Zinc-free lubricating compositions and methods of use thereof

Abstract

The present disclosure generally relates to a lubricating composition having an oil of lubricating viscosity, an ashless phosphorus-containing antiwear agent, an alkaline earth metal detergent, an ashless antioxidant, and an ashless dispersant, and is substantially free of zinc, and a method of lubricating an engine with such a lubricating composition. The lubricating composition is useful as an alternative lubricating composition that reduces and / or eliminates zinc to achieve desired performance goals of the lubricating composition. The present disclosure relates to a substantially zinc-free lubricating composition and a method of using the same. The lubricating composition includes a base oil of lubricating viscosity, an ashless phosphorus-containing antiwear agent, an alkaline earth metal detergent, an ashless antioxidant, and an ashless dispersant. The lubricating composition is substantially free of zinc. The present disclosure further includes a method of using the lubricating composition to reduce low speed pre-ignition ("LSPI") in an engine operating under conditions favorable to LSPI events.

Description

[Background technology]

[0001] Modern engine designs are being developed to improve fuel economy without sacrificing performance or durability. Traditionally, gasoline is injected through the intake port using port fuel injection (PFI), which allows it to enter the combustion chamber via the intake valve. Gasoline Direct Injection (GDI) involves the direct injection of gasoline into the combustion chamber.

[0002] In certain circumstances, an internal combustion engine may exhibit abnormal combustion, which in a spark-started internal combustion engine may be understood as an uncontrolled explosion occurring within the combustion chamber as a result of ignition of combustible elements therein by a source other than the igniter.

[0003] Pre-ignition can be understood as an abnormal combustion form caused by the ignition of the air-fuel mixture before the ignition by the igniter. Pre-ignition can be understood whenever the air-fuel mixture in the combustion chamber is ignited before the igniter is ignited.

[0004] It is now known that zinc-containing antiwear agents, such as ZDDP, have been shown to reduce and / or mitigate LSPI in direct injection engines. However, zinc-containing antiwear agents contribute to sulfated ash in lubricating compositions. Zinc-containing antiwear agents also contribute to particulate matter in lubricating compositions, which can affect cleanliness, deposit formation, fuel economy, and emission quality. Furthermore, zinc antiwear agents are subject to environmental scrutiny. Therefore, it is desirable to reduce or eliminate zinc antiwear agents with zinc-free alternatives that have the desired performance results.

[0005] Therefore, there is a continuing need to develop lubricant compositions that reduce and / or eliminate zinc using ashless substitutes to achieve desired lubricant performance goals.

[0006] The lubricant compositions of the present disclosure address one or more of the aforementioned concerns, including reducing or mitigating LSPI, by using a lubricant composition having at least an ashless, phosphorus-containing antiwear agent. Summary of the Invention [Means for solving the problem]

[0007] The present disclosure relates to a lubricating composition and a method of lubricating an engine with said lubricating composition. The lubricating composition comprises a base oil of lubricating viscosity, an ashless phosphorus-containing antiwear agent, an alkaline earth metal detergent, an ashless antioxidant, and an ashless dispersant. The lubricating composition is further defined by being substantially free of zinc. The ashless phosphorus-containing antiwear agent described in the above composition may comprise an alkyl phosphate amine salt.

[0008] The present disclosure further includes a lubricating composition having a base oil of lubricating viscosity, an alkyl phosphate amine salt antiwear agent in an amount having at least 30 mole percent of phosphorus atoms in the pyrophosphate structure and providing 500 ppm to 900 ppm of phosphorus to the lubricating composition, selected alkaline earth metal detergents including calcium sulfonate detergents and magnesium sulfonate detergents, ashless antioxidants including alkylated diarylamine and sulfurized olefins, and ashless dispersants including polyisobutylene succinimide dispersants and borated polyisobutylene succinimide dispersants, the lubricating composition being substantially free of zinc.

[0009] The disclosure further relates to a method of reducing low speed pre-ignition ("LSPI") in a spark ignition, direct injection internal combustion engine operating under a load having a brake mean effective pressure (BMEP) of 10 bar or greater at a speed of 3,000 rpm or less by supplying to the engine a lubricating composition comprising a base oil of lubricating viscosity, an ashless, phosphorus-containing antiwear agent, an alkaline earth metal detergent, an ashless antioxidant, and an ashless dispersant, the lubricating composition being further defined by being substantially free of zinc.

[0010] The disclosure further relates to a method of reducing LSPI in a spark ignition, direct injection internal combustion engine operating at a speed of 3,000 rpm or less and under a load having a brake mean effective pressure (BMEP) of 10 bar or greater by supplying to the engine a lubricating composition having a base oil of lubricating viscosity and an alkyl phosphate amine salt antiwear agent in an amount having at least 30 mole percent of phosphorus atoms in the pyrophosphate structure and providing 500 ppm to 900 ppm of phosphorus to the lubricating composition, wherein the selected alkaline earth metal detergents include calcium sulfonate detergents and magnesium sulfonate detergents, the ashless antioxidants include alkylated diarylamine and sulfurized olefins, the ashless dispersants include polyisobutylene succinimide dispersants and borated polyisobutylene succinimide dispersants, and the lubricating composition is substantially free of zinc.

[0011] The disclosure further relates to the use of a lubricating composition comprising a base oil of lubricating viscosity, an ashless phosphorus-containing antiwear agent, an alkaline earth metal detergent, an ashless antioxidant, and an ashless dispersant, the lubricating composition being further defined by being substantially free of zinc, to reduce LSPI in a spark ignition, direct injection internal combustion engine operating under a load having a brake mean effective pressure (BMEP) of 10 bar or greater at a speed of 3,000 rpm or less.

[0012] The disclosure further relates to the use of a lubricating composition comprising a base oil of lubricating viscosity, an alkyl phosphate amine salt antiwear agent in an amount having at least 30 mole percent of phosphorus atoms in the pyrophosphate structure and providing 500 ppm to 900 ppm of phosphorus to the lubricating composition, selected alkaline earth metal detergents including calcium sulfonate detergents and magnesium sulfonate detergents, ashless antioxidants including alkylated diarylamines and sulfurized olefins, and ashless dispersants including polyisobutylene succinimide dispersants and borated polyisobutylene succinimide dispersants, wherein the lubricating composition is substantially free of zinc, for reducing LSPI in a spark ignition, direct injection internal combustion engine operating under a load having a brake mean effective pressure (BMEP) of 10 bar or greater at a speed of 3,000 rpm or less. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present disclosure relates to a substantially zinc-free lubricating composition and a method of using the same. The lubricating composition includes a base oil of lubricating viscosity, an ashless phosphorus-containing antiwear agent, an alkaline earth metal detergent, an ashless antioxidant, and an ashless dispersant. The lubricating composition is substantially zinc-free. The disclosure further includes a method of using the lubricating composition to reduce low speed pre-ignition ("LSPI") in an engine operating under conditions favorable to LSPI events.

[0014] Oil of lubricating viscosity One component of the composition of the present disclosure is an oil of lubricating viscosity. As used herein, oil of lubricating viscosity can include natural oils and synthetic oils, oils derived from hydrocracking, hydroprocessing and hydrofinishing, unrefined oils, refined oils, rerefined oils or mixtures thereof. A more detailed description of unrefined oils, refined oils and rerefined oils is provided in paragraphs

[0054] to

[0056] of WO 2008 / 147704 (a similar disclosure is provided in U.S. Patent Application No. 2010 / 197536, see

[0072] to

[0073] ). A more detailed description of natural oils and synthetic lubricating oils is provided in paragraphs

[0058] to

[0059] of WO 2008 / 147704, respectively (a similar disclosure is provided in U.S. Patent Application No. 2010 / 197536, see

[0075] to

[0076] ). The cited portions of both references are incorporated herein. Synthetic oils may also be produced by Fischer-Tropsch reactions and typically may be hydroisomerized Fischer-Tropsch hydrocarbons or waxes. In one embodiment, the oils may be prepared by Fischer-Tropsch gas-to-liquid synthesis procedures, as well as other gas-to-liquid oils.

[0015] Suitable oils may be produced from biological, i.e., natural, sources or by biotechnological methods, including both natural oils such as vegetable oils and triglyceride oils, which may be further refined or purified by standard processes, and oils that may be derived from the direct biological conversion of natural chemicals to oils or the biological formation of building block precursor molecules that may be further converted to oils by known processes.

[0016] Oils of lubricating viscosity may also be defined as set forth in the April 2008 edition of "Appendix E-API Base Oil Interchangeability Guidelines for Passenger Car motor Oils and Diesel Engine Oils," Section 1.3, Subheading 1.3. They may also be defined as specified in "Base Stock Categories." The API guidelines are also summarized in U.S. Patent No. 7,285,516 (see column 11, line 64 to column 12, line 10), which are incorporated herein by reference.

[0017] In one embodiment, the oil of lubricating viscosity can be a mineral oil, ester or synthetic oil of API Groups I-IV, or mixtures thereof. In one embodiment, the oil of lubricating viscosity can be a mineral oil, ester or synthetic oil of API Groups II, III, IV, or mixtures thereof.

[0018] The amount of oil of lubricating viscosity present is typically the remainder after subtracting the combined amount of the dispersant additive package and additional additives (if any) according to the present disclosure from 100% by weight. In some embodiments, the oil of lubricating viscosity may be 80-95% by weight of the lubricating composition. In other embodiments, the oil of lubricating viscosity may be 80-90% by weight of the lubricating composition.

[0019] For purposes of this disclosure, an oil of lubricating viscosity is an oil having a kinematic viscosity of 2.4 mS / g measured at 100° C. 2 / s~6.4m 2In some embodiments, the kinematic viscosity may be 4.0 m / s. 2 / s~5.0m 2 / s, or 5.2m 2 / s~5.8m 2 / s, or 6.0m 2 / s~6.5m 2 In another embodiment, the kinematic viscosity is 6.2 m 2 / s, or 5.6m 2 / s, or 4.6m 2 / s.

[0020] The lubricating compositions claimed herein may be in the form of concentrates and / or fully formulated lubricants. When the lubricating composition is in the form of a concentrate (which may be combined with additional oil to form, in whole or in part, a finished lubricant), the ratio of the components disclosed herein to oil of lubricating viscosity and / or to diluent oil includes ranges from 1:99 to 99:1 by weight, or from 80:20 to 10:90 by weight.

[0021] Ashless phosphorus-containing anti-wear agent The lubricating composition disclosed herein further comprises an ashless phosphorus-containing antiwear agent. In one embodiment, the ashless phosphorus-containing antiwear agent is an organic phosphorus compound. Suitable ashless phosphorus-containing antiwear agents include phosphites, (thio)phosphates, (thio)phosphate amine salts, and combinations thereof. In some embodiments, the ashless phosphorus-containing antiwear agent may also contain sulfur atoms. In other embodiments, the phosphorus-containing antiwear agent is free or substantially free of sulfur. In one embodiment, if present, the sulfur content of the phosphorus-containing antiwear agent is such that the weight ratio of sulfur to phosphorus is less than 2 to 1, or less than 1.75 to 1.

[0022] In one embodiment, the ashless phosphorus-containing antiwear agent is a phosphite. Suitable phosphites include those having at least one hydrocarbyl group with 3 or more, or 8 or more, or 12 or more carbon atoms. The phosphite may be a monohydrocarbyl-substituted phosphite, a dihydrocarbyl-substituted phosphite, or a trihydrocarbyl-substituted phosphite. The phosphite may be represented by the following formula: [ka] wherein at least one R can be a hydrocarbyl group containing at least three carbon atoms and the other R group can be hydrogen. In one embodiment, two of the R groups are hydrocarbyl groups and the third is hydrogen. In one embodiment, each R group is a hydrocarbyl group, i.e., the phosphite is a trihydrocarbyl-substituted phosphite. The hydrocarbyl groups may be alkyl, cycloalkyl, aryl, acyclic or mixtures thereof. The R hydrocarbyl groups can be linear or branched, typically linear, and saturated or unsaturated, typically saturated. In one embodiment, the phosphite is a phosphite according to formula I, wherein R is C 18 Hydrocarbyl, phenyl moiety, C 14 ~C 18 alkyl, or a combination thereof.

[0023] In one embodiment, the ashless phosphorus-containing antiwear agent is 12~22 It may be a hydrocarbyl phosphite or mixtures thereof, i.e., each R may independently be hydrogen or a hydrocarbyl group having 12 to 24, or 14 to 20, carbon atoms, typically 16 to 18 carbon atoms. 12~22 Hydrocarbyl phosphite is C 16~18 Contains hydrocarbyl phosphites. 3 , R 4 , and R 5Examples of alkyl groups include octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, octadecenyl, nonadecyl, eicosyl, or mixtures thereof. 3~8 It may be a hydrocarbyl phosphite or mixtures thereof, i.e., each R may independently be hydrogen or a hydrocarbyl group having 3 to 8, or 4 to 6 carbon atoms, typically 4 carbon atoms. Typically, C 3~8 Hydrocarbyl phosphites include dibutyl phosphite.

[0024] The phosphite used herein may further comprise a phosphite ester, which comprises the reaction product of (a) monomeric phosphorous acid or an ester thereof with (b) at least two alkylene diols, i.e., a first alkylene diol (i) having two hydroxyl groups in a 1,4 or 1,5 or 1,6 relationship, and a second alkylene diol (ii) which is an alkyl-substituted 1,3-propylene diol, one or more of whose alkyl substituents are on one or more carbon atoms of a propylene unit, and the total number of carbon atoms in the alkyl-substituted 1,3-propylene diol is 5 or 6 to 12, wherein the relative molar amount of the monomeric phosphorous acid or an ester thereof (a) to the sum of the alkylene diols (b) is in a ratio of 0.9:1.1 to 1.1:0.9, and the relative molar amount of the first alkylene diol (i) to the alkyl-substituted 1,3-propylene diol (ii) is in a ratio of 30:70 to 65:35.

[0025] The phosphites used herein may further comprise a sulfur-containing phosphite. Suitable sulfur-containing phosphites include those having the formula: [ka] Examples of the above are represented by the following formula: In the formula, R 1 and R 2are each independently a hydrocarbyl group of 3 to about 12 carbon atoms, or 6 to 8 carbon atoms, [ka] is a group represented by Or, in the formula, R 1 and R 2 forms a ring containing 2 to 6 carbon atoms together with the adjacent O and P atoms; R 3 is hydrogen or a methyl group, R 4 is an alkylene group having 2 to 6 carbon atoms, R 5 is hydrogen or a hydrocarbyl group having 1 to about 12 carbon atoms; and n is 1 or 2.

[0026] In another embodiment, the ashless phosphorus-containing antiwear agent may be a (thio)phosphate. When the term "thio" is in parentheses before a chemical identifier, it is understood that the thio group is optional. Thus, for example, "(thio)phosphate" includes both phosphate and thiophosphate compounds.

[0027] In one embodiment, the (thio)phosphate is a dithiophosphate ester. A suitable dithiophosphate ester can be formed by reacting a dithiophosphoric acid represented by (RO)2PSSH with an unsaturated compound. In one embodiment, the unsaturated compound is an unsaturated carboxylic acid or ester. Examples of unsaturated carboxylic acids or anhydrides include acrylic acid or esters thereof, methacrylic acid or esters thereof, itaconic acid or esters thereof, fumaric acid or esters thereof, and maleic acid, its anhydride or esters thereof.

[0028] Examples of (thio)phosphates include phosphorus-containing amide esters, which can be prepared by the reaction of phosphorus acids (e.g., dithiophosphoric acids) with unsaturated amides. Examples of unsaturated amides include acrylamide, N,N'-methylenebisacrylamide, methacrylamide, crotonamide, and the like. The reaction product of the phosphate with the unsaturated amide may be further reacted with a linking or coupling compound, such as formaldehyde or paraformaldehyde. Phosphorus-containing amides are known in the art and are disclosed in U.S. Patent Nos. 4,670,169, 4,770,807, and 4,876,374, which are incorporated by reference for their disclosure of phosphorus amides and their preparation.

[0029] In another embodiment, the ashless phosphorus-containing antiwear agent may be a (thio)phosphate amine salt. In one embodiment, the (thio)phosphate amine salt is an amine alkylthiophosphate, where the alkylthiophosphate is reacted with an epoxide or a polyhydric alcohol (e.g., glycerol). The reaction product may be used alone or may be further reacted with a phosphate, anhydride, or lower ester. The epoxide is generally an aliphatic epoxide or styrene oxide. Examples of useful epoxides include ethylene oxide, propylene oxide, butene oxide, octene oxide, dodecene oxide, styrene oxide, and the like, with ethylene oxide and propylene oxide being preferred. The polyhydric alcohol may be an aliphatic glycol having 1 to about 12, or about 2 to about 6, or 2 or 3 carbon atoms. Glycols include ethylene glycol, propylene glycol, and the like. Alkylthiophosphates, glycols, epoxides, inorganic phosphorus reagents and methods of reacting them are described in US Pat. Nos. 3,197,405 and 3,544,465, which are incorporated herein by reference.

[0030] In another embodiment, the (thio)phosphate amine salts include amine salts of phosphoric acid hydrocarbyl esters prepared by reacting phosphorus pentoxide with an alcohol (having 4 to 28 carbon atoms) followed by reaction with a primary amine (e.g., 2-ethylhexylamine), a secondary amine (e.g., dimethylamine) or a tertiary amine (e.g., dimethyloleylamine) to form the amine salt of the phosphoric acid hydrocarbyl ester. Suitable alcohols include those containing up to 30 or 24, or up to 12 carbon atoms, including primary or secondary alcohols such as isopropyl alcohol, butyl alcohol, amyl alcohol, sec-amyl alcohol, 2-ethylhexyl alcohol, hexyl alcohol, cyclohexyl alcohol, octyl alcohol, decyl alcohol and oleyl alcohol, as well as any of the various commercially available alcohol mixtures having, for example, 8 to 10, 12 to 18, or 18 to 28 carbon atoms.

[0031] In another embodiment, the (thio)phosphate amine salt comprises a substantially sulfur-free alkyl phosphate amine salt. The alkyl phosphate amine salt has at least 30 mole percent of the phosphorus atoms in an alkyl pyrophosphate structure as opposed to an orthophosphate (or monomeric phosphate) structure. The percentage of phosphorus atoms in the pyrophosphate structure may be 30-100 mole %, or 40-90%, or 50-80%, or 55-70%, or 55-65%. The remaining amount of phosphorus atoms may be in an orthophosphate structure or may consist partially of unreacted phosphate or other phosphorus species. In one embodiment, up to 60 or up to 50 mole percent of the phosphorus atoms are in a mono- or di-alkyl-orthophosphate salt structure.

[0032] The substantially sulfur-free alkyl phosphate amine salts present in the pyrophosphate form (sometimes referred to as POP structures) are represented in part by the following formula (I) and / or (II): [ka] It is expressed as: Formula (V) represents a semi-neutralized phosphorus salt, and formula (VI) represents a fully neutralized salt. It is believed that both of the two hydroxy hydrogen atoms of the initially formed phosphate structure are sufficiently acidic to be neutralized by the amine, so that formula (VI) may prevail when a stoichiometrically sufficient amount of amine is present. The actual degree of neutralization, i.e., the degree of salting out of the -OH groups of the phosphorus ester, may be 50% to 100%, or 80% to 99%, or 90% to 98%, or 93% to 97%, or about 95%, which may be determined or calculated based on the amount of amine charged to the phosphate ester mixture. Variations of these materials may exist, such as variants of formula (V) or formula (VI), where the -OH group in formula (V) is replaced by another -OR. 1 or one or more -OR groups. 1 The group is replaced with an -OH group or R 1 The group may be a phosphorus-containing group (i.e., a terminal R 1 In place of the aryl group, a tertiary phosphorus structure is substituted. Exemplary variant structures may include: [ka]

[0033] The structures of formulas (V) and (VI) are shown as completely sulfur-free species in that the phosphorus atoms are bonded to oxygen rather than sulfur atoms, however, it is possible that a small mole fraction of O atoms may be replaced by S atoms, such as 0-5 percent, or 0.1-4 percent, or 0.2-3 percent, or 0.5-2 percent.

[0034] These pyrophosphates have the general structure: [ka] can be distinguished from the ortho-pyrophosphate salt of It may optionally also be present in the amounts described above.

[0035] In formulas (V) and (VI), each R 1are independently alkyl groups of 3 to 12 carbon atoms. In certain embodiments, at least 80 mole percent, or at least 85, 90, 95, or 99 percent of the alkyl groups are secondary alkyl groups. In some embodiments, the alkyl groups can have 4 to 12 carbon atoms, or 5 to 10, or 6 to 8 carbon atoms. Such groups include 2-butyl, 2-pentyl, 3-pentyl, 3-methyl-2-butyl, 2-hexyl, 3-hexyl, cyclohexyl, 4-methyl-2-pentyl, and other such secondary groups and isomers thereof having 6, 7, 8, 9, 10, 11, or 12 carbon atoms. In some embodiments, the alkyl groups can have a methyl branch at the α-position of the group, an example of which is the 4-methyl-2-pentyl (also referred to as 4-methylpent-2-yl) group.

[0036] Such alkyl (including cycloalkyl) groups are typically produced by reaction of the corresponding alcohol or alcohols with phosphorus pentoxide (herein referred to as P2O5, although the more likely structure is P4O5). 10 Typically, 2-3.1 moles of alcohol are produced per mole of P2O5, resulting in a mixture of partial esters, such as mono- and diesters of orthophosphate structure and diesters of pyrophosphate structure. [ka]

[0037] In certain embodiments, 2.5 to 3 moles of alcohol may be provided per mole of P2O5, or 2.2 to 2.8 moles per mole, or even 2.2 to 2.4 moles per mole. 2.5 to 3 (or 2.2 to 2.8 or 2.2 to 2.4) moles of alcohol may typically be made available (i.e., included in the reaction mixture) to react with P2O5, but the actual reaction usually consumes less than 3 moles / mole. Thus, alkyl phosphate amine salts may be prepared by reacting phosphorus pentoxide with a secondary alcohol having 4 to 12 carbon atoms, and reacting the product with an amine, as described in more detail below.

[0038] The reaction conditions and reactants may be selected to favor the formation of esters of pyrophosphate structures and relatively disfavor the formation of orthophosphate monoesters and orthophosphate diesters. The use of secondary alcohols rather than primary alcohols has been found to favor the formation of pyrophosphate structures. Preferred synthesis temperatures include 30-60°C or 35-50°C or 40-50°C or 30-40°C or about 35°C, and in some embodiments the reaction temperature may be 50-60°C. Subsequent heating at 60-80°C or about 70°C after initial mixing of the components may be desirable. It may be desirable to avoid overheating the reaction mixture, especially if the temperature is 60°C or higher, or to discontinue heating once the reaction is substantially complete. This will be apparent to those skilled in the art. In certain embodiments, the reaction temperature does not exceed 62°C or 61°C or 60°C. Preferred conditions may also include the exclusion of water from the outside. The progress of the reaction and the relative amounts of the various phosphorus species may be monitored by infrared spectroscopy and 31 P or 1 This can be measured by spectroscopic means known to those skilled in the art, such as 1 H NMR spectroscopy.

[0039] The pyrophosphate esters can be isolated from the orthoesters if desired, although it is possible, and may be commercially preferable, to use the reaction mixture without separating the components.

[0040] The pyrophosphate, phosphate ester or mixture of phosphate esters reacts with an amine to form an amine salt. The amine is represented by R 2 3N, where each R 2 are independently hydrogen or a hydrocarbyl group or an ester-containing group or an ether-containing group, provided that at least one R 2 The group is a hydrocarbyl group or an ester-containing group or an ether-containing group (i.e., not NH3). Suitable hydrocarbyl amines include primary amines having 1 to 18 carbon atoms or 3 to 12 or 4 to 10 carbon atoms, such as methylamine, ethylamine, propylamine, isopropylamine, butylamine and its isomers, pentylamine and its isomers, hexylamine and its isomers, heptylamine and its isomers, octylamine and its isomers, such as isooctylamine and 2-ethylhexylamine, and higher amines. Other primary amines include dodecylamine, fatty amines, such as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, and oleylamine. Other useful fatty amines include commercially available fatty amines ("Armeen®" amines) (Akzo and Armeen® SD), where the letter designation refers to the fatty acid, such as coco, oleyl, tallow, or stearyl group.

[0041] Secondary amines that may be used include dimethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine, bis-2-ethylhexylamine, N-methyl-1-amino-cyclohexane, Armeen® 2C, and ethylamylamine. The secondary amines may be cyclic amines such as piperidine, piperazine, and morpholine.

[0042] Suitable tertiary amines include tri-n-butylamine, tri-n-octylamine, tri-decylamine, tri-laurylamine, tri-hexadecylamine, and dimethyloleylamine (Armeen® DMOD). Triisodecylamine or tridecylamine and their isomers can be used.

[0043] Examples of mixtures of amines include (i) amines having 11 to 14 carbon atoms in the tertiary alkyl primary group, (ii) amines having 14 to 18 carbon atoms in the tertiary alkyl primary group, or (iii) amines having 18 to 22 carbon atoms in the tertiary alkyl primary group. Other examples of tertiary alkyl primary amines include tert-butylamine, tert-hexylamine, tert-octylamine (such as 1,1-dimethylhexylamine), tert-decylamine (such as 1,1-dimethyloctylamine), tert-dodecylamine, tert-tetradecylamine, tert-hexadecylamine, tert-octadecylamine, tert-tetracosanylamine, and tert-octacosanylamine. In one embodiment, a useful mixture of amines includes "Primene® 81R" or "Primene® JMT". Primene® 81R and Primene® JMT (both manufactured and sold by Rohm & Haas) are 11 ~C 14 Mixture of tertiary alkyl primary amines and C 18 ~C 22 It may be a mixture of tertiary alkyl primary amines.

[0044] In other embodiments, the amine may be an ester-containing amine, such as an N-hydrocarbyl substituted γ- or δ-amino(thio)ester, and is therefore a secondary amine. One or both of the O atoms of the ester group may be replaced with sulfur, although typically no sulfur atom is present. N-substituted γ-amino esters are [ka] It can be expressed by In addition, the N-substituted δ-amino ester is [ka] It can be expressed as:

[0045] One or more additional substituents or groups may also be present at the α, β, γ, or δ positions of the amino ester. In one embodiment, no such substituents are present. In another embodiment, a substituent is present at the β position, and thus in certain embodiments, [ka]

[0036] R and R 4 is as defined below, X is O or S (in one embodiment, O), and R 5 is hydrogen, a hydrocarbyl group, or -C(=O)-R 6 wherein R 6 is a hydrogen atom, an alkyl group, or -X'-R 7 where X' is O or S, and R 7 R is a hydrocarbyl group of 1 to 30 carbon atoms. That is, the substituents at the β-positions of the chain may include ester, thioester, carbonyl, or hydrocarbyl groups. 5 -C(=O)-R 6 Then the structure is [ka] It can be expressed as: It is understood that similar structures for δ-amino esters are included, such as, for example: [ka] It could be. R 6 -X'-R 7 It will be apparent that when R is a substituted succinate ester or thioester, in one embodiment the material may specifically be a methyl succinate diester with amine substitution on the methyl group. 4 Groups and R 7 The groups may be the same or different. In certain embodiments, they are independently selected from R 4 As described below for: [ka] It can be represented by the structure: In certain embodiments, the material is or includes 2-((hydrocarbyl)-amino-methylsuccinic acid dihydrocarbyl esters (which may also be referred to as dihydrocarbyl 2-((hydrocarbyl)aminomethyl succinates).

[0046] In the above structure, the hydrocarbyl substituent R on the amine nitrogen may comprise a hydrocarbyl group of at least 3 carbon atoms having a branch at the 1- or 2- (i.e., α- or β-) position of the hydrocarbyl chain (not to be confused with the α- or β-position of the ester group described above). Such branched hydrocarbyl groups R have the subformula [ka] It can be expressed by where the bond on the right represents the point of attachment to the nitrogen atom. In this substructure, n is 0 or 1, and R 1 is hydrogen or a hydrocarbyl group, R 2 and R3 may be independently hydrocarbyl groups or may be taken together to form a carboxylic acid structure. The hydrocarbyl groups may be aliphatic, alicyclic, or aromatic, or mixtures thereof. When n is 0, the branching is at the 1 or α position of the group. When n is 1, the branching is at the 2 or β position. The R 4 When is methyl, n can be 0 in some embodiments. [ka] Of course, it may be branched at both positions 1 and 2. Bonds to a cyclic structure are considered branched. [ka] (1- or alpha branch type)

[0047] Thus, the branched hydrocarbyl substituent R on the amine nitrogen can include groups such as isopropyl, cyclopropyl, sec-butyl, iso-butyl, t-butyl, 1-ethyl-propyl, 1,2-dimethylpropyl, neopentyl, cyclohexyl, 4-heptyl, 2-ethyl-1-hexyl (commonly referred to as 2-ethylhexyl), t-octyl (e.g., 1,1-dimethyl-1-hexyl), 4-heptyl, 2-propylheptyl, adamantyl, and α-methylbenzyl.

[0048] In the above structure, the alcohol residue portion R 4 may have 1 to 30, or 1 to 18, or 1 to 12, or 2 to 8 carbon atoms. It may be a hydrocarbyl group or a hydrocarbon group. It may be aliphatic, alicyclic, branched aliphatic, or aromatic. In certain embodiments, R 4 The group can be methyl, ethyl, propyl, isopropyl, n-butyl, iso-butyl, t-butyl, n-hexyl, cyclohexyl, iso-octyl, or 2-ethylhexyl. 4 When is methyl, the R group that is the hydrocarbyl substituent on the nitrogen can often have a branch at the 1 position. 4The group may be an ether-containing group, for example, it may be an ether-containing group or a polyether-containing group, which may contain, for example, from 2 to 120 carbon atoms, together with the oxygen atom representing the ether functionality.

[0049] In another embodiment, R 4 R may be a hydroxy- or polyhydroxy-containing alkyl group having 2-12 carbon atoms. Such materials may be based on a diol (e.g., ethylene glycol or propylene glycol), one of whose hydroxy groups may react to form an ester bond, leaving one unesterified alkyl group. Another example of a material may be glycerin, which may leave one or two hydroxy groups after condensation. Other polyhydroxy materials include pentaerythritol and trimethylolpropane. Optionally, one or more of the hydroxy groups may react to form an ester or thioester. In one embodiment, R 4 One or more of the hydroxy groups within may be condensed with or bonded to additional groups to form a crosslinked species.

[0050] In one embodiment, the amine has the structure [ka] It can be expressed as: In the formula, R 6 and R 7 are independently alkyl groups having from 1 to about 6 carbon atoms; R 8 and R 9 are independently an alkyl group having 1 to about 12 carbon atoms.

[0051] The N-hydrocarbyl substituted γ-amino ester or γ-amino thioester materials disclosed herein can typically be prepared by Michael addition of a primary amine having a branched hydrocarbyl group as described above with an ethylenically unsaturated ester or thioester of the type described above. The ethylenic unsaturation, in this example, is between the β and γ carbon atoms of the ester. Thus, the reaction can be carried out, for example, by [ka] It can happen like this: where the X and R groups are as defined above. In one embodiment, the ethylenically unsaturated ester may be an ester of itaconic acid. In this structure, n may be 0 or 1, and R 1 may be hydrogen or a hydrocarbyl group, R 2 and R 3 can be independently a hydrocarbyl group or can be taken together to form a carbocyclic structure, X is O or S, and R 4 can be a hydrocarbyl group of 1 to 30 carbon atoms, and R 5 is hydrogen, a hydrocarbyl group, or -C(=O)-R 6 In the formula, R 6 is hydrogen, an alkyl group, or -X'-R 7 where X' is O or S, and R 7 is a hydrocarbyl group of 1 to 30 carbon atoms. In one embodiment, the amine reactant is not a tertiary hydrocarbyl (e.g., t-alkyl) primary amine, i.e., n is not 0, but R 1 , R 2 , and R 3 are each a hydrocarbyl group.

[0052] The amines that can react to form the Michael addition products described above can be primary amines, such that the resulting products are secondary amines having the branched R substituents described above, with the nitrogen also attached to the remainder of the molecule.

[0053] The N-hydrocarbyl substituted δ-amino ester or δ-amino thioester materials disclosed herein can be prepared by reductive amination of esters of 5-oxy-substituted carboxylic acids or thiocarboxylic acids. They can also be prepared by amination of esters of 5-halogen-substituted carboxylic acids or thiocarboxylic acids, or by reductive amination of esters of 2-amino-substituted hexanedioic acids, or by alkylation of esters of 2-aminohexanedioic acids.

[0054] Details of N-substituted γ-amino esters and their synthesis can be found in International Publication No. WO 2014 / 074335, Lubrizol, May 15, 2014. Details of N-substituted δ-amino esters and their synthesis can be found in International Application No. US2015 / 027958 (Lubrizol, filed April 28, 2015) and U.S. Patent Application No. 61 / 989306 (filed May 6, 2015).

[0055] The amine, whatever type it may be, reacts to neutralize the acidic groups on the phosphorus ester component, including the pyrophosphate esters described above as well as any orthophosphate esters that may be present.

[0056] In one embodiment, the ashless phosphorus-containing antiwear agent is an alkyl phosphate amine salt. The amine phosphate may be derived from a mono- or dihydrocarbyl phosphate (typically an alkyl phosphate), or a mixture thereof. The alkyl of the mono- or dihydrocarbyl phosphate may include a linear or branched alkyl group of 3 to 36 carbon atoms. The hydrocarbyl group of the linear or branched hydrocarbyl phosphate may contain 4 to 30, or 8 to 20 carbon atoms. Examples of suitable hydrocarbyl groups of the hydrocarbyl phosphate may include isopropyl, n-butyl, sec-butyl, amyl, 4-methyl-2-pentyl (i.e., methylamyl), n-hexyl, n-heptyl, n-octyl, iso-octyl, 2-ethylhexyl, nonyl, 2-propylheptyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, oleyl, or combinations thereof. In one embodiment, the phosphate is a mixture of mono- and di-(2-ethylhexyl) phosphate.

[0057] Examples of suitable primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine, and dodecylamine, as well as fatty amines such as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, and oleamine. Other useful fatty amines include commercially available fatty amines such as "Armeen" amines (products available from Akzo Chemicals, Chicago, Ill.), such as Armeen C, Armeen O, Armeen OL, Armeen T, Armeen HT, Armeen S, and Armeen SD, where the letter designation refers to the aliphatic, such as coco, oleyl, tallow, or stearyl group.

[0058] The compositions disclosed herein may include an amine dialkyldithiophosphate. Examples of suitable amine (or ammonium) dialkyldithiophosphates include those having the formula: [ka] Examples of the salts include In the formula, R 8 and R 9 are independently hydrocarbyl groups containing 3 to 30, 3 to 20, 3 to 16, or 3 to 14 carbon atoms, and by reacting phosphorus pentasulfide (P2S5) with an alcohol or a phenol, a compound of the formula: [ka] can be readily obtained by forming the corresponding O,O-dihydrocarbyl phosphorodithioic acid.

[0059] The reaction involves mixing four moles of an alcohol or phenol with one mole of phosphorus pentasulfide at a temperature between 20°C and 200°C. Hydrogen sulfide is liberated in the reaction. This acid is then reacted with a basic amine (or ammonium) compound to form a salt.

[0060] In some embodiments, R 8 Groups and R 9 The groups are independently hydrocarbyl groups, typically free of acetylenic unsaturation, and usually free of ethylenic unsaturation. They are typically alkyl, cycloalkyl, aralkyl, or alkaryl groups, having from 3 to 20 carbon atoms, e.g., from 3 to 16 carbon atoms, or up to 13 carbon atoms, e.g., from 3 to 12 carbon atoms. 8 and R 9 The alcohol providing the radical may be a mixture of secondary and primary alcohols, for example, a mixture of 2-ethylhexanol and 2-propanol, or a mixture of secondary alcohols, for example, 2-propanol and 4-methyl-2-pentanol.

[0061] In certain embodiments, the dialkyldithiophosphate is selected to reduce the volatility of phosphorus from the lubricant, i.e., to increase the retention of phosphorus in the lubricant. 8 Groups and R 9 Suitable formulations for achieving good phosphorus retention in engines are disclosed, for example, in U.S. Patent Application Publication No. 2008-0015129, see, for example, the claims.

[0062] Such amine salts are often referred to as amine dialkyldithiophosphates or simply amine dithiophosphates. They are well known and readily available to those skilled in the art of lubricant formulation. The additional zinc dialkyldithiophosphates may be described as primary zinc dialkyldithiophosphates or secondary zinc dialkyldithiophosphates depending on the structure of the alcohol used in their preparation. In some embodiments, the compositions of the present invention include primary zinc dialkyldithiophosphates. In some embodiments, the compositions of the present invention include secondary zinc dialkyldithiophosphates. In some embodiments, the compositions of the present invention include a mixture of primary zinc dialkyldithiophosphates and secondary zinc dialkyldithiophosphates. In some embodiments, the amine salt is a mixture of primary and secondary dialkyldithiophosphates, where the ratio of primary dialkyldithiophosphates to secondary dialkyldithiophosphates (by weight) is at least 1:1, or at least 1:1.2, or at least 1:1.5, or 1:2, or 1:10. In some embodiments, the amine phosphate is a mixture of primary and secondary dialkyl dithiophosphates, where the secondary dialkyl dithiophosphate is at least 50% by weight of the primary, or even at least 60, 70, 80, or even 90% by weight of the primary.

[0063] In one embodiment, the alkyl phosphate amine salt is an alkyl dithiophosphate amine salt. Zinc dialkyl dithiophosphates are known in the art. The amine dithiophosphates can include linear or branched alkyl groups containing 3 to 20 carbon atoms, or 3 to 12 carbon atoms, or 4 to 8 carbon atoms.

[0064] Examples of dithiophosphates which may be amine salts include isopropyl methylamyl dithiophosphate, isopropyl isooctyl dithiophosphate, di(cyclohexyl)dithiophosphate, isobutyl 2-ethylhexyl dithiophosphate, isopropyl 2-ethylhexyl dithiophosphate, isobutyl isoamyl dithiophosphate, isopropyl n-butyl dithiophosphate, and combinations thereof.

[0065] The ashless, phosphorus-containing antiwear agent may be present in the lubricating composition in an amount of 0.1 to 1.5 wt.%. In another embodiment, the ashless, phosphorus-containing antiwear agent is present in the lubricating composition in an amount of 0.3 to 1.2 wt.%. In yet another embodiment, the ashless, phosphorus-containing antiwear agent is present in the lubricating composition in an amount of 0.5 to 1.1 wt.%. In another embodiment, the ashless, phosphorus-containing antiwear agent is present in the lubricating composition in an amount of 0.6 to 0.9 wt.%.

[0066] In certain embodiments, the amount of ashless phosphorus-containing antiwear agent is defined by the amount of phosphorus it can provide to the lubricating composition. In such embodiments, the ashless phosphorus-containing antiwear agent is present in an amount that provides 500-900 ppm of phosphorus to the lubricating composition. In another embodiment, the ashless phosphorus-containing antiwear agent is present in an amount that provides 550-850 ppm of phosphorus to the lubricating composition. In another embodiment, the ashless phosphorus-containing antiwear agent is present in an amount that provides 600-825 ppm of phosphorus to the lubricating composition. In another embodiment, the ashless phosphorus-containing antiwear agent is present in an amount that provides 650-800 ppm of phosphorus to the lubricating composition. In another embodiment, the ashless phosphorus-containing antiwear agent is present in an amount that provides 700-800 ppm of phosphorus to the lubricating composition.

[0067] Alkaline Earth Metal Detergents The lubricating compositions disclosed herein further comprise an alkaline earth metal detergent. Suitable alkaline earth metal detergents include metal overbased detergents.

[0068] Metal overbased detergents, also called overbased detergents, metal-containing overbased detergents or superbased salts, are characterized by a metal content in excess of that required for stoichiometric neutralization of the metal and the particular acidic organic compound (i.e., the substrate with which the metal reacts). Overbased detergents may include one or more of non-sulfur-containing phenates, sulfur-containing phenates, sulfonates, salicylates, and mixtures thereof.

[0069] The amount of excess metal is generally expressed as a substrate to metal ratio. The term "metal ratio" is used in the prior art and herein to define the ratio of the total chemical equivalents of metal in the overbased salt to the chemical equivalents of metal in the salt that would be expected to result from the reaction between the hydrocarbyl-substituted organic acid, i.e. the hydrocarbyl-substituted phenol or mixtures thereof to be overbased, and the basic metal compound according to the known chemical reactivity and stoichiometry of the two reactants. The hydrocarbyl-substituted phenol or mixtures thereof is overbased, and the basic metal compound according to the known chemical reactivity and stoichiometry of the two reactants. Thus, in normal or neutral salts (i.e. soaps), the metal ratio is 1, and in overbased salts, the metal ratio is greater than 1, especially greater than 1.3. The overbased detergent of the present invention may have a metal ratio of 5 to 30, or a metal ratio of 7 to 22, or a metal ratio of at least 11.

[0070] Metal-containing detergents may also include "hybrid" detergents formed with mixed surfactant systems containing phenate and / or sulfonate components, such as phenate-salicylate, sulfonate-phenate, sulfonate-salicylate, sulfonate-phenate-salicylate, as described, for example, in U.S. Pat. Nos. 6,429,178, 6,429,179, 6,153,565, and 6,281,179. For example, when a hybrid sulfonate / phenate detergent is used, the hybrid detergent is considered to be equivalent in amount to separate phenate and sulfonate detergents that incorporate similar amounts of phenate and sulfonate soaps, respectively. Overbased phenates and salicylates typically have a total base number of 180 to 450 TBN. Overbased sulfonates typically have a total base number of 250 to 600, or 300 to 500. Overbased detergents are known in the art.

[0071] Alkylphenols are often used as components in and / or as components of overbased detergents. Alkylphenols may be used to prepare phenate, salicylate, salixarate, or saligenin detergents or mixtures thereof. Suitable alkylphenols may include para-substituted hydrocarbylphenols. The hydrocarbyl group may be a straight or branched chain aliphatic group of 1 to 60 carbon atoms, 8 to 40 carbon atoms, 10 to 24 carbon atoms, 12 to 20 carbon atoms, or 16 to 24 carbon atoms. In one embodiment, the alkylphenol overbased detergent is prepared from an alkylphenol or mixture thereof that is free or substantially free (i.e., contains less than 0.1 weight percent) of p-dodecylphenol. In one embodiment, the lubricating composition of the present invention contains less than 0.3 weight percent alkylphenol, less than 0.1 weight percent alkylphenol, or less than 0.05 weight percent alkylphenol.

[0072] The overbased metal-containing detergent may be an alkali metal salt or an alkaline earth metal salt. In an embodiment, the overbased detergent may be a sodium, calcium, magnesium salt of phenates, sulfur-containing phenates, sulfonates, salixarates, and salicylates, or a mixture thereof. In an embodiment, the overbased detergent is a calcium detergent, a magnesium detergent, or a mixture thereof. In an embodiment, the overbased calcium detergent may be present in an amount that provides the lubricating composition with at least 500 ppm by weight of calcium and up to 3000 ppm by weight of calcium, or at least 1000 ppm by weight of calcium, or at least 2000 ppm by weight of calcium, or up to 2500 ppm by weight of calcium. In an embodiment, the overbased detergent may be present in an amount that provides the lubricating composition with up to 500 ppm by weight of magnesium, or up to 330 ppm by weight of magnesium, or up to 125 ppm by weight of magnesium, or up to 45 ppm by weight of magnesium. In one embodiment, the lubricating composition is essentially free of magnesium (i.e., less than 10 ppm magnesium) resulting from overbased detergents. In one embodiment, the overbased detergent may be present in an amount that provides the lubricating composition with at least 200 ppm magnesium by weight, or at least 450 ppm magnesium by weight, or at least 700 ppm magnesium by weight. In one embodiment, both calcium-containing detergents and magnesium-containing detergents may be present in the lubricating composition. The calcium detergents and magnesium detergents may be present such that the weight ratio of calcium to magnesium is 10:1 to 1:10, or 8:3 to 4:5, or 1:1 to 1:3. In one embodiment, the overbased detergent is free or substantially free of sodium.

[0073] In one embodiment, the sulfonate detergent may be primarily a linear alkylbenzene sulfonate detergent having a metal ratio of at least 8, as described in U.S. Patent Publication No. 2005 / 065045 (and issued as U.S. Patent No. 7,407,919), paragraphs

[0026] to

[0037] . The linear alkylbenzene sulfonate detergent may be particularly useful in helping to improve fuel economy. The linear alkyl group may be attached to the benzene ring at any position along the linear chain of the alkyl group, but is often attached at the 2-, 3- or 4-position of the linear chain, and in some cases is attached primarily at the 2-position, resulting in a linear alkylbenzene sulfonate detergent.

[0074] Salicylate detergents and overbased salicylate detergents may be prepared in at least two different ways. Carbonylation (also called carboxylation) of p-alkylphenols is described in many references, including U.S. Pat. No. 8,399,388. Carbonylation can be followed by overbasing to form overbased salicylate detergents. Suitable p-alkylphenols include those having linear and / or branched hydrocarbyl groups of 1 to 60 carbon atoms. Salicylate detergents may also be prepared by alkylation of salicylic acid followed by overbasing, as described in U.S. Pat. No. 7,009,072. Salicylate detergents prepared in this manner may be prepared from linear and / or branched alkylating agents (usually 1-olefins) containing 6 to 50 carbon atoms, 10 to 30 carbon atoms, or 14 to 24 carbon atoms. In one embodiment, the overbased detergent of the present invention is a salicylate detergent. In one embodiment, the salicylate detergent of the present invention is free of unreacted p-alkylphenol (i.e., contains less than 0.1% by weight).In one embodiment, the salicylate detergent of the present invention is prepared by alkylation of salicylic acid.

[0075] In some embodiments, the metal of the alkaline earth metal detergent is selected from calcium, magnesium, or mixtures thereof. In one embodiment, the alkaline earth metal detergent is a calcium sulfonate detergent. In another embodiment, the alkaline earth metal detergent is a magnesium sulfonate detergent. In one embodiment, the alkaline earth metal detergent is a mixture of two or more alkaline earth metal detergents. In embodiments where the alkaline earth metal detergent is a mixture, the mixture may include a calcium sulfonate detergent and a magnesium sulfonate detergent.

[0076] The alkaline earth metal detergent may be present in the lubricating composition in an amount of 0.3 to 2.5 wt %, based on the total weight of the lubricating composition. In one embodiment, the alkaline earth metal detergent may be present in the lubricating composition in an amount of 0.5 to 2.0 wt %, based on the total weight of the lubricating composition. In another embodiment, the alkaline earth metal detergent may be present in the lubricating composition in an amount of 0.6 to 1.8 wt %, based on the total weight of the lubricating composition. In an embodiment having a mixture of alkaline earth metal detergents, one detergent may be present in the lubricating composition in an amount of 0.4 to 0.8 wt %, and a second detergent may be present in an amount of 0.6 to 1.1 wt %. The total amount of the mixture of alkaline earth metal detergents in the lubricating composition may be about 0.8 to 2.0 wt %. In one embodiment, the alkaline earth metal detergents include a calcium sulfonate detergent present in the lubricating composition in an amount from 0.4 to 0.8 wt %, and a magnesium sulfonate detergent present in the lubricating composition in an amount from 0.6 to 1.1 wt %, based on the total weight of the lubricating composition.

[0077] Ashless antioxidant The lubricating compositions disclosed herein further comprise an ashless antioxidant, which includes arylamines, diarylamines, alkylated arylamines, alkylated diarylamines, phenols, hindered phenols, sulfurized olefins, and mixtures thereof.

[0078] Suitable arylamines include secondary or tertiary amines substituted with a single (optionally substituted) aryl group attached to the amine nitrogen. Examples of arylamines include N-alkylnaphthylamines, which can have one or two N-alkyl groups, i.e., the nitrogen group is mono- or di-substituted. In one embodiment, the nitrogen group is predominantly mono-substituted. The N-alkyl group may be acyclic, cyclic, or alicyclic. The acyclic alkyl group may be branched.

[0079] The diarylamine or alkylated diarylamine may be phenyl-α-naphthylamine (PANA), alkylated diphenylamine, or alkylated phenylnaphthylamine, or mixtures thereof. The alkylated diphenylamine may include di-nonylated diphenylamine, nonyl diphenylamine, octyl diphenylamine, di-octylated diphenylamine, di-decylated diphenylamine, decyl diphenylamine, and mixtures thereof. In an embodiment, the diphenylamine may include nonyl diphenylamine, dinonyl diphenylamine, octyl diphenylamine, dioctyl diphenylamine, or mixtures thereof. In an embodiment, the alkylated diphenylamine may include nonyl diphenylamine or dinonyl diphenylamine. The alkylated diarylamine may include octyl, dioctyl, nonyl, dinonyl, decyl, or didecyl phenylnaphthylamine.

[0080] The diarylamine of the present invention also has the formula: [ka] It can be expressed by wherein R1 and R2, together with the carbon atoms to which they are attached, are bonded together to form a 5-, 6-, or 7-membered ring (such as a carbocyclic ring or a cyclic hydrocarbylene ring); R3 and R4 are independently hydrogen, a hydrocarbyl group, or a moiety that, together with the carbon atoms to which they are attached, forms a 5-, 6-, or 7-membered ring (such as a carbocyclic ring or a cyclic hydrocarbylene ring); R5 and R6 are independently hydrogen, a hydrocarbyl group, or a moiety that, together with the carbon atoms to which they are attached, forms a ring or represents zero carbons or a direct bond between rings (typically a hydrocarbyl moiety); and R7 is hydrogen or a hydrocarbyl group.

[0081] In one embodiment, the diarylamine is N-phenyl-naphthylamine (PNA).

[0082] In another embodiment, the diarylamine has the formula: [ka] It can be expressed as wherein R3 and R4 are defined as above.

[0083] In another embodiment, the diarylamine compound has the general formula: [ka] Includes those having wherein R7 is defined as above, R5 and R6 are independently hydrogen, a hydrocarbyl group, or may be joined together to form a ring, such as a dihydroacridan, n=1 or 2, and Y and Z independently represent carbon or heteroatoms such as N, O, and S.

[0084] In certain embodiments, the diarylamine compound has the formula: [ka] Includes those listed below.

[0085] In one embodiment, the diarylamine has the formula: [ka] is a dihydroacridan derivative of wherein R1, R2, R3, and R4 are defined as above, and R8 and R9 are independently hydrogen or a hydrocarbyl group of 1 to 20 carbon atoms.

[0086] In one embodiment, the diarylamine is selected such that R5 and R6 represent a direct (or zero carbon) linkage between the aryl rings. The result is a diarylamine of the formula: [ka] is a carbazole of wherein R1, R2, R3, and R4 are defined as above.

[0087] The diarylamine antioxidant may be present in the lubricating composition from 0.1 wt % to 10 wt %, from 0.35 wt % to 5 wt %, or even from 0.5 wt % to 2 wt %, or from 0.1 to 2.1 wt %, or from 0.2 to 1.8 wt %, based on the total weight of the lubricating composition.

[0088] The phenolic antioxidants may be simple alkylphenols, hindered phenols, or bound phenolic compounds.

[0089] Hindered phenol antioxidants often contain secondary butyl and / or tertiary butyl groups as steric hindrance groups. The phenol group may be further substituted with a hydrocarbyl group (typically linear or branched alkyl) and / or a bridging group that connects to a second aromatic group. Examples of suitable hindered phenol antioxidants include 2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol or 4-butyl-2,6-di-tert-butylphenol, 4-dodecyl-2,6-di-tert-butylphenol, or butyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate. In one embodiment, the hindered phenol antioxidant may be an ester, such as Irganox™ L-135 from Ciba.

[0090] Bound phenols often contain two alkylphenols that are linked to an alkylene group to form a bisphenol compound. Examples of suitable bound phenol compounds include 4,4'-methylenebis-(2,6-di-tert-butylphenol), 4-methyl-2,6-di-tert-butylphenol, 2,2'-bis-(6-t-butyl-4-heptylphenol), 4,4'-bis(2,6-di-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), and 2,2'-methylenebis(4-ethyl-6-t-butylphenol).

[0091] Phenols of the present invention also include polyaromatic compounds and their derivatives. Examples of suitable polyaromatic compounds include gallic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 1,4-dihydroxy-2-naphthoic acid, 3,5-dihydroxynaphthoic acid, 3,7-dihydroxynaphthoic acid, and mixtures thereof.

[0092] In one embodiment, the phenolic antioxidant comprises a hindered phenol, hi another embodiment, the hindered phenol is derived from 2,6-di-tertbutylphenol.

[0093] In one embodiment, the lubricating composition of the present disclosure comprises a phenolic antioxidant in the range of 0.01% to 5%, or 0.1% to 4%, or 0.1 to 2.1%, or 0.2 to 1.8%, or 0.2% to 3%, or 0.5% to 2% by weight of the lubricating composition.

[0094] Sulfurized olefins are well-known commercial materials and are readily available that are substantially nitrogen-free, i.e., contain no nitrogen functionality. Olefinic compounds that can be sulfurized are diverse in nature. They contain at least one olefinic double bond, defined as a non-aromatic double bond, i.e., connecting two aliphatic carbon atoms. These materials generally have sulfide bonds containing 1-10, e.g., 1-4, or 1 or 2 sulfur atoms.

[0095] The ashless antioxidants of the present invention can be used separately or in combination, in one embodiment, two or more different antioxidants are used in combination such that each of the at least two antioxidants is present at least 0.1 weight percent, with the total amount of ashless antioxidant being 0.5 to 5 weight percent.

[0096] The ashless antioxidant may be present in an amount of from 0.1 to 2.1 wt %, or from 0.2 to 1.8 wt %, based on the total weight of the lubricating composition.

[0097] In one embodiment, the ashless antioxidant is an alkylated diarylamine. In another embodiment, the ashless antioxidant is a sulfurized olefin. In yet another embodiment, the ashless antioxidant is a mixture of ashless antioxidants comprising 0.8-1.3 wt.% alkylated diarylamine and 0.1-0.5 wt.% sulfurized olefin.

[0098] Ashless Dispersant The lubricating compositions disclosed herein further comprise an ashless dispersant. The dispersant may be a succinimide dispersant, a Mannich dispersant, a polyolefin succinic acid ester, amide, or ester-amide, or a mixture thereof. In one embodiment, the dispersant may be a borated succinimide dispersant. In one embodiment, the dispersant may be a borated succinimide dispersant. In one embodiment, the dispersant may be present as a single dispersant. In another embodiment, the dispersant may be present as a mixture of two or three different dispersants.

[0099] The succinimide dispersant may be derived from an aliphatic polyamine or mixtures thereof. The aliphatic polyamine may be an aliphatic polyamine such as ethylene polyamine, propylene polyamine, butylene polyamine, or mixtures thereof. In one embodiment, the aliphatic polyamine may be an ethylene polyamine. In one embodiment, the aliphatic polyamine may be selected from the group consisting of ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, polyamine distillation bottoms, and mixtures thereof.

[0100] The succinimide dispersant may be derived from an aromatic amine, an aromatic polyamine, or a mixture thereof. The aromatic amine may be 4-aminodiphenylamine (ADPA) (also known as N-phenylphenylenediamine), a derivative of ADPA (described in U.S. Patent Publications 2011 / 0306528 and 2010 / 0298185), nitroaniline, aminocarbazole, amino-indazolinone, aminopyrimidine, 4-(4-nitrophenylazo)aniline, or a combination thereof. In one embodiment, the dispersant is a derivative of an aromatic amine, the aromatic amine having at least three discontinuous aromatic rings.

[0101] The succinimide dispersant may be a derivative of a polyetheramine or polyetherpolyamine. A typical polyetheramine compound will contain at least one ether unit and be chain terminated with at least one amine moiety. The polyetherpolyamine may be based on polymers derived from C2-C6 epoxides such as ethylene oxide, propylene oxide, and butylene oxide. Examples of polyetherpolyamines are sold under the Jeffamine® brand and are commercially available from Huntsman Corporation.

[0102] The dispersant may be an N-substituted long chain alkenyl succinimide. Examples of N-substituted long chain alkenyl succinimides include polyisobutylene succinimides. Typically, the polyisobutylene from which the polyisobutylene succinic anhydride is derived has a number average molecular weight of 350 to 5000, or 550 to 3000, or 750 to 2500. Succinimide dispersants and their preparation are described, for example, in U.S. Pat. Nos. 3,172,892, 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170, 3,467, 668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, Re26,433, and 6,165,235, 7,238,650, as well as European Patent No. 0 355 895 (B1).

[0103] Dispersants may also be post-treated in conventional manner by reaction with any of a variety of agents, among them boron compounds, urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, maleic anhydride, nitriles, epoxides, and phosphorus compounds.

[0104] Dispersants may be borated using one or more of a variety of agents selected from the group consisting of various forms of boric acid (including metaboric acid, HBO2, orthoboric acid, H3BO3, and tetraboric acid, H2B4O7), boron oxide, boron trioxide, and alkyl borates. In one embodiment, the boration agent is boric acid, which may be used alone or in combination with other boration agents. Methods for preparing borated dispersants are known in the art. Borated dispersants can be prepared to contain 0.1% to 2.5% by weight boron, or 0.1% to 2.0% by weight boron, or 0.2% to 1.5% by weight boron, or 0.3% to 1.0% by weight boron.

[0105] Suitable polyisobutylenes for use in the succinimide dispersants may include those formed from polyisobutylenes or highly reactive polyisobutylenes having a terminal vinylidene content of at least about 50 mol%, such as about 60 mol%, and especially about 70 mol% to about 90 mol% or greater. Suitable polyisobutenes may include those prepared using BF3 catalysts. In one embodiment, the borated dispersant is derived from a polyolefin having a number average molecular weight of 350 to 3000 Daltons and a vinylidene content of at least 50 mol%, or at least 70 mol%, or at least 90 mol%.

[0106] Dispersants can be prepared / obtained / obtainable from the reaction of succinic anhydride by an "ene" reaction or a "thermal" reaction by what is called the "direct alkylation process". The "ene" reaction mechanism and general reaction conditions are summarized in "Maleic Anhydride", pp. 147-149, edited by BC Trivedi and BC Culbertson, published by Plenum Press (1982). Dispersants prepared by processes involving the "ene" reaction may be polyisobutylene succinimides with less than 50 mol%, or 0-30 mol%, or 0-20 mol%, or 0 mol% of carbon rings present in the dispersant molecules. The "ene" reaction may have a reaction temperature of less than 180°C to 300°C, or 200°C to 250°C, or 200°C to 220°C.

[0107] Dispersants may also be obtained / obtainable from a chlorine-assisted process, which often involves Diels-Alder chemistry and leads to the formation of carbon ring bonds. This process is known to those skilled in the art. The chlorine-assisted process may produce dispersants that are polyisobutylene succinimides with carbon rings present in 50 mole % or more, or 60-100 mole % of the dispersant molecules. Both the thermal process and the chlorine-assisted process are described in more detail in U.S. Pat. No. 7,615,521, columns 4-5, and preparation examples A and B.

[0108] Dispersants can be used alone or as part of a mixture of non-borated or borated dispersants. When a mixture of dispersants is used there can be 2 to 5, or 2 to 3, or 2 dispersants.

[0109] The polyolefin dispersant may comprise a polyalphaolefin (PAO) containing dispersant selected from the group consisting of polyalphaolefin succinimides, polyalphaolefin succinamides, polyalphaolefin acid esters, polyalphaolefin oxazolines, polyalphaolefin imidazolines, polyalphaolefin succinamide imidazolines, and combinations thereof.

[0110] Polyalphaolefins (PAOs) useful as feedstocks in forming PAO-containing dispersants are derived from the oligomerization or polymerization of ethylene, propylene, and α-olefins. Suitable α-olefins include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, and 1-octadecene. Commercial production of PAOs typically uses feedstocks containing mixtures of two or more of the aforementioned monomers and other hydrocarbons. PAOs can be in the form of dimers, trimers, tetramers, polymers, and the like.

[0111] PAOs can be reacted with maleic anhydride (MA) to form polyalphaolefin succinic anhydrides (PAO-SA), and the anhydrides can then be reacted with one or more of polyamines, aminoalcohols, and alcohols / polyols to form polyalphaolefin succinimides, polyalphaolefin succinamides, polyalphaolefin succinate esters, polyalphaolefin oxazolines, polyalphaolefin imidazolines, polyalphaolefin-succinamide-imidazolines, and mixtures thereof.

[0112] Another class of ashless dispersants are the Mannich bases, which are materials formed by the condensation of high molecular weight alkyl-substituted phenols, alkylene polyamines, and aldehydes such as formaldehyde, and are described in more detail in U.S. Pat. No. 3,634,515.

[0113] Useful nitrogen-containing dispersants include the product of a Mannich reaction between (a) an aldehyde, (b) a polyamine, and (c) an optionally substituted phenol. The phenol may be substituted such that the Mannich product has a molecular weight of less than 7500. Optionally, the molecular weight may be less than 2000, less than 1500, less than 1300, or, for example, less than 1200, less than 1100, less than 1000. In some embodiments, the Mannich product has a molecular weight of less than 900, less than 850, or less than 800, less than 500, or less than 400. The substituted phenol may be substituted with up to four groups on the aromatic ring. For example, it may be a tri- or di-substituted phenol. In some embodiments, the phenol may be a mono-substituted phenol. The substitutions may be in the ortho, meta, and / or para positions. To form the Mannich product, the molar ratio of aldehyde to amine is 4:1 to 1:1, or 2:1 to 1:1. The molar ratio of aldehyde to phenol may be at least 0.75:1, preferably 0.75 to 1-4:1, preferably 1:1-4:1, more preferably 1:1-2:1. To form the preferred Mannich product, the molar ratio of phenol to amine is preferably at least 1.5:1, more preferably at least 1.6:1, more preferably at least 1.7:1, such as at least 1.8:1, preferably at least 1.9:1. The molar ratio of phenol to amine may be up to 5:1, for example, it may be up to 4:1 or up to 3.5:1. Suitably, it is up to 3.25:1, up to 3:1, up to 2.5:1, up to 2.3:1 or up to 2.1:1.

[0114] In one embodiment the ashless dispersant is a polyisobutylene succinimide dispersant. In another embodiment the ashless dispersant is a borated polyisobutylene succinimide dispersant. In one embodiment the ashless dispersant is present in the lubricating composition in an amount of from 1 to 6 wt%, or from 2 to 5 wt%, or from 2.5 to 4.5 wt%. In one embodiment the ashless dispersant comprises a mixture of 0.8 to 1.6 wt% of a non-boron containing polyisobutylene succinimide dispersant and 1.8 to 3.1 wt% of a borated polyisobutylene succinimide dispersant. In another embodiment one or more of the boron free polyisobutylene succinimide dispersant and the borated polyisobutylene succinimide dispersant are produced from a direct alkylation process.

[0115] The lubricating compositions disclosed herein are substantially free of zinc. As used herein, "substantially free" means that the lubricating compositions may contain small amounts of the listed components as non-functional additives. In some embodiments, the lubricating compositions may contain less than 50 ppm, or less than 40 ppm, or less than 30 ppm, or less than 20 ppm, or less than 10 ppm, or less than 5 ppm of zinc. In one embodiment, the lubricating compositions are zinc-free, which means that the lubricating compositions contain 0 ppm of zinc.

[0116] Other Additives The lubricating compositions of the present disclosure may optionally contain one or more additional performance additives. These additional performance additives may include one or more metal deactivators, viscosity modifiers, friction modifiers, corrosion inhibitors, dispersant viscosity modifiers, extreme pressure agents, antifoam agents, demulsifiers, pour point depressants, seal swell agents, and any combination or mixture thereof. Typically, a fully formulated lubricating oil will contain one or more of these performance enhancing additives, and often will contain a package of multiple performance enhancing additives.

[0117] Suitable dispersant viscosity modifiers include functionalized polyolefins, such as ethylene-propylene copolymers functionalized with acylating agents such as maleic anhydride and amines, amine-functionalized polymethacrylates, or esterified styrene-maleic anhydride copolymers reacted with amines. More detailed descriptions of dispersant viscosity modifiers are disclosed in WO 2006 / 015130, or U.S. Pat. Nos. 4,863,623, 6,107,257, 6,107,258, and 6,117,825. In one embodiment, the dispersant viscosity modifier may include those described in U.S. Pat. No. 4,863,623 (see column 2, line 15 to column 3, line 52) or WO 2006 / 015130 (page 2, paragraph

[0008] and preparation examples are described in paragraphs

[0065] to

[0073] ).

[0118] In one embodiment, the present invention provides a lubricating composition further comprising a molybdenum compound. The molybdenum compound may be selected from the group consisting of molybdenum dialkyldithiophosphates, molybdenum dithiocarbamates, amine salts of molybdenum compounds, and mixtures thereof. The molybdenum compound may provide 0 to 1000 ppm, or 5 to 1000 ppm, or 10 to 750 ppm, or 5 ppm to 300 ppm, or 20 ppm to 250 ppm of molybdenum to the lubricating composition.

[0119] In one embodiment, the present invention provides a lubricating composition further comprising a friction modifier. Examples of friction modifiers include long chain fatty acid derivatives of amines, fatty esters or epoxides; fatty imidazolines, such as condensation products of carboxylic acids with polyalkylene-polyamines; amine salts of alkyl phosphates; fatty alkyl tartrates; fatty alkyl tartrate imides; or fatty alkyl tartramides. The term fatty as used herein may mean having a straight chain alkyl group of C8-22.

[0120] Friction modifiers may also include materials such as sulfurized fatty compounds and olefins, molybdenum dialkyldithiophosphates, molybdenum dithiocarbamates, sunflower oil, or monoesters of polyols and aliphatic carboxylic acids.

[0121] In one embodiment, the friction modifier may be selected from the group consisting of long chain fatty acid derivatives of amines, long chain fatty esters, or long chain fatty epoxides; fatty imidazolines; amine salts of alkyl phosphates; fatty alkyl tartrates; fatty alkyl tartrimides; and fatty alkyl tartramides. The friction modifier may be present at 0% to 6%, or 0.05% to 4%, or 0.1% to 2% by weight of the lubricating composition.

[0122] In one embodiment, the friction modifier may be a long chain fatty ester, in another embodiment the long chain fatty ester may be a monoester or diester, or mixtures thereof, and in another embodiment the long chain fatty ester may be a triglyceride.

[0123] Other performance enhancing additives such as corrosion inhibitors include those described in U.S. Application Serial No. 05 / 038319, published as WO 2006 / 047486, paragraphs 5-8, octyl octanamide, condensation products of dodecenyl succinic acid or anhydride and fatty acids such as oleic acid with polyamines. In one embodiment, the corrosion inhibitor includes Synalox (registered trademark of The Dow Chemical Company) corrosion inhibitor. Synalox® corrosion inhibitors can be homopolymers or copolymers of propylene oxide. Synalox® corrosion inhibitors are described in more detail in Form No. 118-01453-0702 AMS issued by The Dow Chemical Company. The product is titled "SYNALOX Lubricants, High-Performance Polyglycols for Demanding Applications."

[0124] The lubricating composition may further comprise metal deactivators such as derivatives of benzotriazole (typically tolyltriazole), dimercaptothiadiazole derivatives, 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole, or 2-alkyldithiobenzothiazole; foam inhibitors such as copolymers of ethyl acrylate and 2-ethylhexyl acrylate and copolymers of ethyl acrylate and 2-ethylhexyl acrylate and vinyl acetate; demulsifiers including trialkyl phosphates, polyethylene glycol, polyethylene oxide, polypropylene oxide, and (ethylene oxide-propylene oxide) polymers; and pour point depressants such as esters of maleic anhydride-styrene, polymethacrylates, polyacrylates, or polyacrylamides.

[0125] Pour point depressants which may be useful in the compositions of the present invention further include polyalphaolefins, esters of maleic anhydride-styrene, poly(meth)acrylates, polyacrylates, or polyacrylamides.

[0126] The lubricant composition for internal combustion engines may be suitable for any engine lubricant, regardless of sulfur, phosphorus, or sulfated ash (ASTM D-874) content. The sulfur content of the engine oil lubricant may be 1.1 wt% or less, or 0.9 wt% or less, or 0.5 wt% or less, or 0.3 wt% or less. In an embodiment, the sulfur content may range from 0.001 wt% to 0.5 wt%, or 0.01 wt% to 0.3 wt%, or 0.5 to 1.0 wt%. The phosphorus content may be 0.2 wt% or less, or 0.12 wt% or less, or 0.1 wt% or less, or 0.085 wt% or less, or 0.08 wt% or less, or even 0.06 wt% or less, 0.055 wt% or less, or 0.05 wt% or less. In one embodiment, the phosphorus content may be 100 ppm to 1000 ppm, or 200 ppm to 900 ppm, or 300 to 875, or 400 to 850, or 600 to 800. The total sulfated ash content may be 2 wt% or less, or 1.5 wt% or less, or 1.1 wt% or less, or 1 wt% or less, or 0.8 wt% or less, or 0.5 wt% or less, or 0.4 wt% or less. In one embodiment, the total sulfated ash content may range from 0.05 wt% to 0.9 wt%, or 0.1 wt% to 0.2 wt% or 0.45 wt%.

[0127] In one embodiment, the lubricating composition may be an engine oil, and the lubricating composition may be characterized as having at least one of: (i) a sulfur content of less than or equal to 0.5 wt. %, (ii) a phosphorus content of less than or equal to 0.1 wt. %, (iii) a sulfated ash content of less than or equal to 1.5 wt. %, or a combination thereof.

[0128] The lubricating compositions may be used to reduce or eliminate low speed pre-ignition ("LSPI") in an engine. In one embodiment, the lubricating compositions disclosed herein may be used in a method to reduce LSPI in a direct injection engine by supplying the lubricating composition to the engine. LSPI events may be catastrophic in nature. Thus, it is desirable to significantly reduce or even eliminate LSPI events during normal or sustained operation of a direct fuel injection engine.

[0129] When direct injection engines are operated at speeds below 3,000 rpm and loads above 10 bar brake mean effective pressure (BMEP), LSPI events can occur. An LSPI event can consist of one or more LSPI combustion cycles, and typically consists of multiple LSPI combustion cycles occurring consecutively or alternating with normal combustion cycles in between. Without being bound to a particular theory, LSPI may result from the combustion of oil droplets, or oil-fuel mixture droplets, or combinations thereof, that may accumulate in the piston top land clearance volume, or in the piston ring land and ring groove clearances. Lubricating oil may migrate from under the oil control ring to the piston top land area due to abnormal piston ring motion. At low speed, high load conditions, the in-cylinder pressure dynamics (compression and ignition pressures) may be significantly different from the in-cylinder pressures at low loads due to significantly delayed combustion phasing and high boost and peak compression pressures that may affect ring kinematics in particular.

[0130] At the aforementioned loads, LSPI can be accompanied by a subsequent detonation and / or severe engine knock, which can cause severe damage to the engine very quickly (often within 1-5 engine cycles). Given that multiple flames may be present after a normal spark is provided from the igniter, engine knock can occur with LSPI. The present invention aims to provide a method for suppressing or reducing LSPI events, comprising supplying an engine with a lubricant composition as disclosed herein.

[0131] Generally, lubricants are added to the lubrication system of an internal combustion engine to then deliver the lubricating composition to critical parts of the engine that require lubrication during operation. The engine components may have steel or aluminum surfaces (typically steel surfaces) and may be coated with, for example, a diamond-like carbon (DLC) coating.

[0132] The aluminum surface may be comprised of an aluminum alloy, which may be a eutectic or hypereutectic aluminum alloy (such as those derived from aluminum silicate, aluminum oxide, or other ceramic materials). The aluminum surface may be present on a cylinder bore, cylinder block, or piston ring having an aluminum alloy or aluminum composite.

[0133] The internal combustion engine may be fitted with an emission control system or a turbocharger. Examples of emission control systems include diesel particulate filters (DPFs), or systems that use selective catalytic reduction (SCR).

[0134] The internal combustion engine of the present invention is distinguished from a gas turbine, in which each individual combustion event is converted from a linear reciprocating force to a rotational torque via a rod and crankshaft. In contrast, in a gas turbine (sometimes called a jet engine), a continuous combustion process is not converted but instead produces a continuous rotational torque that can generate thrust at the exhaust. These differences in the operating conditions of a gas turbine and an internal combustion engine result in different operating environments and stresses.

[0135] In one embodiment of the invention, the engine operates at a speed between 500 rpm and 3000 rpm, or between 800 rpm and 2800 rpm, or even between 1000 rpm and 2600 rpm, or less than 3,000 rpm, or less than 2,500 rpm, or less than 2,000 rpm. Additionally, the engine may be operated at a mean effective pressure between 10 bar and 15 bar, or between 10 and 20 bar, or between 10 and 30 bar, or between 12 bar and 24 bar.

[0136] In one embodiment, the disclosure relates to a lubricant composition as disclosed herein, which is capable of reducing low speed pre-ignition events in a spark ignition, direct injection internal combustion engine operating under a load having a brake mean effective pressure (BMEP) of 10 bar or greater at a speed of 3,000 rpm or less.

[0137] In another embodiment, the disclosure relates to a method of reducing low speed pre-ignition by supplying a lubricant composition disclosed herein to a spark ignition, direct injection internal combustion engine, the method further comprising supplying any one of the lubricant compositions disclosed herein to a spark ignition, direct injection internal combustion engine operating at a speed of 3,000 rpm or less under a load having a mean effective pressure (BMEP) of 10 bar or greater.

[0138] In some embodiments, the engine may be fueled with a liquid hydrocarbon fuel, a liquid non-hydrocarbon fuel, or a mixture thereof.

[0139] The present disclosure further relates to the use of any one of the lubricant compositions disclosed herein for reducing low speed pre-ignition in a spark ignition direct injection internal combustion engine.

[0140] In different embodiments, the lubricating composition may have a composition as set forth in the table below. [Table 4] EXAMPLES

[0141] The present disclosure is further illustrated by the following examples which set forth particularly advantageous embodiments. The examples are provided to illustrate the invention and are not intended to limit the invention.

[0142] Ashless (i.e., metal-free) phosphorus compounds were evaluated for preventing and reducing wear and reducing low speed pre-ignition in low viscosity lubricating compositions. Several ashless compounds were prepared as detailed below and some were obtained from commercial sources summarized below (Table 1).

[0143] Preparation Example A (EXA) (Part i) 4-Methyl-2-pentanol (1250 g) is charged to a 3 L reaction vessel equipped with a high shear mixer and a screw feed powder addition funnel and heated to 60° C. Solid phosphorus pentoxide (752.5 g) is charged to the addition funnel and added over 1 hour 45 minutes with the high shear mixer operating at 6000 rpm. The reaction mixture is held at 60° C. for an additional 1.5 hours, after which the mixture is vacuum stripped for 30 minutes to give the intermediate alkyl phosphate (1958.5 g).

[0144] (Part ii) The alkyl phosphoric acid (12,030 g) from part (i) above (combined with a previous similar batch) is charged to a reaction vessel equipped with an overhead stirrer, thermocouple, and nitrogen inlet and heated to 60° C. (2-Ethylhexyl)amine (802.4 g) is added dropwise to the reaction vessel over 1.2 hours. After approximately half of the amine addition is complete, diluent oil (350 g) is added. The resulting orange liquid product is used without further purification (2,352.3 g).

[0145] Preparation Example B (EXB) (Part i) 2-Hydroxyethyl acrylate (97% purity, 797 g, 6.65 mol) warmed to 40° C. is added to a 5 L, 4-neck round bottom flask equipped with a nitrogen subsurface inlet, thermocouple, mechanical glass rod stirrer, and a Friedrichs cold water condenser connected to a 25% sodium hydroxide trap and a bleach trap. To this, O,O'-di(4-methyl-2-pentyl)dithiophosphoric acid (2500 g, 6.86 mol, based on total acid number by analysis) is added dropwise using a pressure equalizing addition funnel at a temperature between 55° C. and 65° C. over a period of 2 hours (may be 1 to 2.5 hours). After the addition is complete, the reaction temperature is set to 65° C. (may be 65° C. to 70° C.) and the reaction is stirred at this temperature for 7 hours (may be 3 to 5 hours or until the hydroxyethyl acrylate is consumed). The resulting intermediate is cooled to ambient temperature to give a liquid (3297 g) and stored under inert atmosphere.

[0146] (Part ii) To a similarly equipped 5 L 4-neck round bottom flask, add the intermediate from part i (2872 g, 8.00 moles, based on the amount of available OH groups by analysis). Add anhydrous sodium methoxide (1 g, 18.5 mmol) in one portion and stir the reaction for an additional 5 minutes. Add dimethyl phosphite (449 g, 4.08 moles) in one portion and slowly heat the reaction to 95°C while blowing nitrogen through a surface tube at about 28 L / hr (about 1.0 sfch). Hold the reaction mixture at 95°C (may be 90-100°C) for 8 hours and collect the distillate, which is removed via a Dean-Stark trap. Strip the reaction mixture under reduced pressure (2.7 kPa, 20 mmHg) at 95°C for 2 hours to obtain additional distillate. Add 30 g of filter aid, dried overnight in an oven set at 90°C, to the flask and stir for an additional 15 minutes. The filter cake is packed under vacuum into a Büchner funnel using 55 g of additional filter aid. The contents of the 5 L flask are then filtered through the cake to give the product as a pale yellowish-brown clear liquid (2802 g, 9.5 wt % phosphorus).

[0147] Preparation Example C (EXC) Dimethyl hydrogen phosphite (18.61 kg) is charged to a 2 L round bottom flask equipped with a Dean-Stark water jacketed condenser, mechanical stirrer, and nitrogen inlet. 2-Ethyl-2-butyl-1,3-propanediol (37.1 kg) is melted in a steam chest and added to the phosphite in one portion. The reaction mixture is heated to 135° C. under nitrogen with stirring at 300 rpm. After the distillation of methanol is complete (3.5 hours), 1,6-hexanediol (200 g) is added in one portion and the resulting mixture is stirred for an additional 2 hours. The resulting product mixture is vacuum stripped at 135° C. for 30 minutes to produce a clear, slightly yellow liquid (42.1 kg; 13.3% by weight phosphorus).

[0148] Preparation Example E (EXE) A 5 L round bottom flask equipped with a reflux condenser, mechanical stirrer, and nitrogen inlet is charged with mixed amyl / isobutyl dialkyl dithiophosphates (60:40 weight ratio of C4 / C5 alkyl groups) (1700 g) and heated to 62° C. Methyl acrylate (196.4 g) is added slowly to maintain the reaction temperature below 80° C. After the addition of the acrylate is complete, the reaction mixture is heated to 98° C. and held at that temperature for 4 hours. The mixture is cooled to 40° C. before propylene oxide (43.7 g) is added via a subsurface tube. The reaction mixture is then heated to 80° C., vacuum stripped, and filtered through a filter aid to produce a clear amber liquid (2020 g). [Table 1]

[0149] A series of 0W-20 lubricating compositions were prepared containing the ashless phosphorus compounds of the present invention, metal detergents, ashless dispersants, antioxidants, and other conventional additives such as polymeric viscosity index improvers, friction modifiers, corrosion inhibitors, pour point depressants, and antifoam agents (Table 1). [Table 2] 1.All treatment speeds are oil-free unless otherwise stated 2. Polyisobutene succinimide prepared from high vinylidene polyisobutene (PIB) (2000 Mn PIB, TBN 26 mg KOH / g) 3. Boronated polyisobutenyl succinimide (2000mn PIB, TBN 26mg KOH / g, 0.8wt% boron) 4. Overbased calcium alkylbenzene sulfonate (TBN 520 mg KOH / g, 20 wt% Ca) 5. Overbased calcium alkylbenzene sulfonate (TBN 690 mg KOH / g, 16 wt% Mg) 6. Other additives include friction modifiers, corrosion inhibitors, pour point depressants, and antifoam agents.

[0150] The lubricant examples were evaluated for their ability to reduce or eliminate pre-ignition events in a low-speed engine operating at high brake mean effective pressure (BMEP), as well as general lubricant performance such as wear reduction, oxidation protection, and detergency / deposit control (Table 3).

[0151] Low Speed ​​Pre-Ignition (LSPI) was evaluated in a Ford 2.0L EcoBoost engine, a turbocharged gasoline direct injection (GDI) engine. The Ford EcoBoost engine is operated at 1750 rpm and 17.0 bar BMEP. The engine is run at these conditions for a total of 175,000 combustion cycles and LSPI events are counted. The two phases are repeated four times and the number of pre-ignition events is recorded as an average. Table 2 below shows the average LSPI events over the four runs. An LSPI event is determined by monitoring the peak cylinder pressure (PP) and the mass fraction burned (MFB) of the fuel charge in the cylinder. An LSPI event is determined to have occurred if both criteria are met. The peak cylinder pressure threshold is typically 9,000-10,000 kPa. The MFB threshold is typically such that at least 2% of the fuel charge is burned late, i.e., before 5.5 degrees after top dead center (ATDC).

[0152] Wear resistance is evaluated in a High Frequency Reciprocating Rig (HFRR), available from PCS Instruments. The test conditions for evaluation were steel ball on hardened steel disk, 200 g load, 60 minutes duration, 20 Hertz frequency, and the temperature was held constant at 120°C.

[0153] Oxidation resistance and cleanability are evaluated with a series of standard bench tests including Komatsu Hot Tube (KHT), Differential Pressure Scanning Calorimetry (PDSC) (e.g., L85-99), MHT TEOST (ASTM D7097), and TEOST 33C (ASTM D6335). [Table 3]

[0154] It is known that some of the materials described above may interact in the final formulation, so that the components of the final formulation may differ from those initially added. The products formed herein, including the products formed upon using the lubricant composition of the present invention in its intended use, may not be easily described. Nevertheless, all such modifications and reaction products are included within the scope of the present invention. The present invention encompasses the lubricant composition prepared by mixing the above components.

[0155] Unless otherwise stated herein, references to treat rates or amounts of components present in the lubricating compositions disclosed herein are quoted on an oil-free basis, i.e., based on the amount of actives.

[0156] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having a predominantly hydrocarbon character, including one or more double bonds. Examples of hydrocarbyl groups include hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic, aliphatic, and alicyclic substituted aromatic substituents, as well as cyclic substituents in which the ring is completed through another part of the molecule (e.g., two substituents together form a ring); substituted hydrocarbon substituents, i.e., substituents containing non-hydrocarbon groups that do not change the predominantly hydrocarbon character of the substituent in the context of the present invention (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy); heterosubstituents, i.e., substituents that have a predominantly hydrocarbon character in the context of the present invention, but contain other than carbon in a ring or chain otherwise composed of carbon atoms, and include substituents as pyridyl, furyl, thienyl, and imidazolyl. Heteroatoms include sulfur, oxygen, and nitrogen. In general, no more than two, or no more than one non-hydrocarbon substituent will be present for every 10 carbon atoms in the hydrocarbyl group, or alternatively, there may be no non-hydrocarbon substituents in the hydrocarbyl group.

[0157] The present disclosure is not limited with respect to the specific embodiments described in this application, but are intended as examples of various aspects. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from the spirit and scope of the present invention. In addition to those enumerated herein, functionally equivalent methods and components within the scope of the present disclosure will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure should be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that the present disclosure is not limited to specific methods, reagents, compounds, or compositions, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0158] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Nothing in this disclosure should be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by prior invention. As used herein, the term "including" means "including, but not limited to."

[0159] Although various compositions, methods, and devices are described in terms of "comprising" (which may be interpreted to mean "including, but not limited to") various components or steps, the compositions, methods, and devices may further "consist essentially of" or "consist of" the various components and steps, and such terminology should be interpreted to define essentially a set of occlusive elements.

[0160] With respect to the use of substantially any plural and / or singular terms herein, those of skill in the art may convert from plural to singular and / or from singular to plural as appropriate to the context and / or application. Various singular / plural conversions may be expressly set forth herein for clarity.

[0161] In general, it will be understood by those skilled in the art that the terms used herein, and particularly the terms used in the appended claims (e.g., the body of the appended claims), are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "including" should be interpreted as "including but not limited to," etc.). Where a specific number of claim recitations being introduced are intended, such intent will be expressly set forth in the claim, and in the absence of such recitation, it will be further understood by those skilled in the art that no such intent exists. For example, as an aid to understanding, the following appended claims may include the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be interpreted as implying that the introduction of a claim recitation with the indefinite article "a" or "an" limits any particular claim that includes such an introduced claim recitation to an embodiment that includes only one such recitation, even if the same claim includes the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should be interpreted to mean "at least one" or "one or more"). The same applies to the use of definite articles used to introduce claim recitations. In addition, even if a specific number of claim recitations being introduced is explicitly recited, one of ordinary skill in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., an express recitation of "two recitations" without other modifiers means at least two recitations, or more than two recitations). Furthermore, when a convention similar to "at least one of A, B, and C, etc." is used, such configurations are generally intended in the sense that one of ordinary skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" includes, but is not limited to, systems having only A, only B, only C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.).When a convention similar to "at least one of A, B, or C, etc." is used, generally such a configuration is intended in the sense that one of ordinary skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, systems having only A, only B, only C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by one of ordinary skill in the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms should be understood to contemplate the possibility of including one of the terms, either of the terms, or both terms, regardless of the specification, claims, or drawings. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0162] Additionally, where features or aspects of the disclosure may be described in terms of a Markush group, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual element or subgroup of elements of the Markush group.

[0163] As will be understood by those of skill in the art, for any and all purposes, including with respect to providing a written description, all ranges disclosed herein encompass any and all possible subranges and combinations thereof. Any recited range can be readily recognized as fully descriptive and allowing for the same range to be broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third, and upper third, etc. As will be understood by those of skill in the art, all phrases such as "up to," "at least," etc. refer to ranges that are inclusive of the recited numbers and can then be broken down into subranges, as discussed above. Finally, as will be understood by those of skill in the art, ranges include each individual element. Thus, for example, a group having 1-3% by weight refers to groups having 1, 2, or 3% by weight. Similarly, a group having 1-5% by weight refers to groups having 1, 2, 3, 4, or 5% by weight, etc., including all points in between.

[0164] Additionally, when stated ranges for treatment rates are provided, such ranges are intended to include the treatment rates for individual components and / or mixtures of components. Thus, for example, a range of 1-3% by weight contemplates that a given component may be present in the range of 1-3% by weight, or that a mixture of similar components may be present in the range of 1-3% by weight.

[0165] As used herein, the term "about" means that a given quantity value is within ±20% of the stated value. In other embodiments, values ​​are within ±15% of the stated value. In other embodiments, values ​​are within ±10% of the stated value. In other embodiments, values ​​are within ±5% of the stated value. In other embodiments, values ​​are within ±2.5% of the stated value. In other embodiments, values ​​are within ±1% of the stated value.

[0166] Unless otherwise specified, "wt. %" as used herein refers to weight percent based on the total weight of the lubricating composition on an oil-free basis.

Claims

1. 1. A lubricant composition comprising: a base oil of lubricating viscosity; an ashless phosphorus-containing antiwear agent; an alkaline earth metal detergent; An ashless antioxidant; an ashless dispersant; A lubricant composition that is substantially free of zinc.

2. The lubricant composition of claim 1, wherein the oil of lubricating viscosity comprises 80 to 95 weight percent of the lubricant composition.

3. The lubricant composition of claim 2, wherein the oil of lubricating viscosity comprises 80 to 90 weight percent of the lubricant composition.

4. 2. The lubricant composition of claim 1, wherein the ashless phosphorus-containing antiwear agent is an organophosphorus antiwear agent.

5. 2. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is selected from phosphites, (thio)phosphates, (thio)phosphate amine salts, and combinations thereof.

6. 6. The lubricant composition of claim 5, wherein the (thio)phosphate amine salt is an alkyl phosphate amine salt.

7. 7. The lubricant composition of claim 6, wherein at least 30 mole percent of the phosphorus atoms in the alkyl phosphate amine salt are of an alkyl pyrophosphate structure.

8. The amine alkyl pyrophosphate salt of claim 1, wherein the amine alkyl pyrophosphate salt is represented by formula (I) or (II): 【Chemistry 1】 [0033] In one embodiment, the species is represented by In the formula, each R １ is independently a primary alkyl group of from about 3 to about 12 carbon atoms; ２ are independently hydrogen or a hydrocarbyl group or an ester-containing group, and at least one R ２ The group is a hydrocarbyl group or an ester containing group, or the -OH group is -OR １ or is substituted with one or more -OR １ The group is substituted with an —OH group or R １ The lubricant composition of claim 7, wherein the group is substituted with a phosphorus-containing group.

9. The amine alkyl pyrophosphate salt of claim 1, wherein the amine alkyl pyrophosphate salt is represented by formula (I) or (II): 【Chemistry 2】 [0033] In one embodiment, the species is represented by In the formula, each R １ is independently a primary alkyl group of from about 3 to about 12 carbon atoms; ２ are independently hydrogen or a hydrocarbyl group or an ester-containing group, and at least one R ２ 9. The lubricant composition of claim 7 or 8, wherein the group is a hydrocarbyl group or an ester-containing group.

10. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in the lubricant composition in an amount of 0.1 to 1.5 weight percent.

11. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in the lubricant composition in an amount of 0.3 to 1.2 weight percent.

12. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in the lubricant composition in an amount of 0.5 to 1.1 weight percent.

13. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in the lubricant composition in an amount of 0.6 to 0.9 weight percent.

14. 10. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in an amount to provide 500 to 900 ppm phosphorus to the lubricant composition.

15. 2. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in an amount to provide 550 to 850 ppm phosphorus to the lubricant composition.

16. 2. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in an amount to provide 600 to 825 ppm phosphorus to the lubricant composition.

17. 2. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in an amount to provide 650 to 800 ppm phosphorus to the lubricant composition.

18. 10. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent is present in an amount to provide 700 to 800 ppm phosphorus to the lubricant composition.

19. 2. The lubricant composition of claim 1, wherein the alkaline earth metal detergent is selected from alkaline earth metal sulfonates, phenates, and salicylates.

20. 20. The lubricant composition of claim 19, wherein the metal of the alkaline earth metal detergent is selected from calcium and magnesium.

21. 21. The lubricant composition of claim 20, wherein the alkaline earth metal detergent is a calcium sulfonate detergent.

22. 21. The lubricant composition of claim 20, wherein the alkaline earth metal detergent is a magnesium sulfonate detergent.

23. The lubricant composition of claim 1, wherein the alkaline earth metal detergent is present in the lubricant composition in an amount of 0.3 to 2.5 weight percent.

24. The lubricant composition of claim 1, wherein the alkaline earth metal detergent is present in the lubricant composition in an amount of 0.5 to 2.0 weight percent.

25. The lubricant composition of claim 1, wherein the alkaline earth metal detergent is present in the lubricant composition in an amount of 0.6 to 1.8 wt %.

26. 2. The lubricant composition of claim 1, wherein the alkaline earth metal detergent comprises a mixture of alkaline earth metal detergents, the mixture being present in the lubricant composition in an amount of 0.8 to 2.0 wt %.

27. 27. The lubricant composition of claim 26, wherein the mixture of alkaline earth metal detergents comprises 0.4 to 0.8 wt % of a calcium sulfonate detergent and 0.6 to 1.1 wt % of a magnesium sulfonate detergent, based on the total weight of the lubricant composition.

28. 2. The lubricant composition of claim 1, wherein the ashless antioxidant is selected from arylamines, diarylamines, alkylated arylamines, alkylated diarylamines, phenols, hindered phenols, sulfurized olefins, and mixtures thereof.

29. 30. The lubricant composition of claim 28, wherein the antioxidant is an alkylated diarylamine.

30. 30. The lubricant composition of claim 28, wherein the antioxidant is a sulfurized olefin.

31. The lubricant composition of claim 1, wherein the antioxidant is present in the lubricant composition in an amount of 0.1 to 2.1 wt %.

32. The lubricant composition of claim 1, wherein the antioxidant is present in the lubricant composition in an amount of 0.2 to 1.8 wt %.

33. 33. The lubricant composition of any one of claims 28 to 32, wherein the antioxidant comprises 0.8 to 1.3 wt. % of an alkylated diarylamine and 0.1 to 0.5 wt. % of a sulfurized olefin.

34. 2. The lubricant composition of claim 1, wherein the ashless dispersant is a polyisobutylene succinimide dispersant.

35. 35. The lubricant composition of claim 34, wherein the polyisobutylene succinimide dispersant is borated.

36. The lubricant composition of claim 1, wherein the ashless dispersant is present in the lubricant composition in an amount from 1 to 6 wt %, or from 2 to 5 wt %, or from 2.5 to 4.5 wt %.

37. 2. The lubricant composition of claim 1, wherein the ashless dispersant comprises 0.8 to 1.6 weight percent of a non-boron containing polyisobutylene succinimide dispersant and 1.8 to 3.1 weight percent of a borated polyisobutylene dispersant.

38. 38. The lubricant composition of claim 37, wherein one or more of the non-boron containing polyisobutylene succinimide dispersant and the borated polyisobutylene succinimide dispersant are produced from a direct alkylation process.

39. 2. The lubricant composition of claim 1, wherein the ashless, phosphorus-containing antiwear agent contains sulfur and has a sulfur to phosphorus ratio of less than 2:1 or 1.75:

1.

40. 2. The lubricant composition of claim 1, wherein the lubricant composition is capable of reducing low speed pre-ignition events in a spark ignition, direct injection internal combustion engine operating under a load having a brake mean effective pressure (BMEP) of 10 bar or more at a speed of 3,000 rpm or less.

41. 13. A method for reducing low speed pre-ignition in a spark ignition, direct injection internal combustion engine comprising supplying the lubricant composition of claim 1 to the engine.

42. 42. The method of claim 41, wherein the engine is operated at a speed of less than or equal to 3,000 rpm under a load having a brake mean effective pressure (BMEP) of 10 bar or greater.

43. 43. A method according to claim 41 or 42, wherein the engine is fuelled with a liquid hydrocarbon fuel, a liquid non-hydrocarbon fuel, or a mixture thereof.

44. 10. Use of the lubricant composition of claim 1 for reducing low speed pre-ignition in a spark ignition, direct injection internal combustion engine.

45. 45. Use according to claim 44, wherein the engine is operated at a speed of not more than 3,000 rpm under a load having a brake mean effective pressure (BMEP) of not less than 10 bar.

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