Zinc-free lubricating composition and method 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 developed to improve fuel efficiency without sacrificing performance or durability. Traditionally, gasoline was injected through port fuel injection (PFI), meaning it was injected through the intake port and flowed into the combustion chamber via the intake valve. Direct gasoline injection (GDI) involves the direct injection of gasoline into the combustion chamber.

[0002] Under certain circumstances, internal combustion engines may exhibit abnormal combustion. In spark-start internal combustion engines, abnormal combustion can be understood as an uncontrolled explosion occurring in the combustion chamber as a result of ignition of combustible elements in the combustion chamber by a cause other than the igniter.

[0003] Premature ignition can be understood as an abnormal combustion pattern that occurs when the air-fuel mixture ignites before the igniter. Premature ignition can be understood whenever the air-fuel mixture in the combustion chamber ignites before the igniter.

[0004] Currently, zinc-containing anti-wear agents such as ZDDP are known to reduce and / or mitigate LSPI in direct injection engines. However, zinc-containing anti-wear agents contribute to sulfated ash in lubrication compositions. They also contribute to particulate matter in lubrication compositions, which can affect cleanliness, deposit formation, fuel economy, and emission quality. Furthermore, zinc anti-wear agents are subject to environmental investigations. Therefore, it is desirable to reduce or eliminate zinc anti-wear agents using zinc-free alternatives that achieve the desired performance results.

[0005] Therefore, there remains a need to develop lubricant compositions that achieve desired performance targets by reducing and / or eliminating zinc using ashless substitutes.

[0006] The lubricant compositions of this disclosure address one or more of the aforementioned concerns, including reducing or mitigating LSPI, by using a lubricant composition having at least a phosphorus-free wear inhibitor. [Overview of the project] [Means for solving the problem]

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

[0008] The present disclosure further includes a lubricating composition comprising a base oil of lubricating viscosity, an alkyl phosphate amine salt anti-wear agent having at least 30 mole percent of phosphorus atoms in its pyrophosphate structure and in an amount that brings 500 ppm to 900 ppm of phosphorus into the lubricating composition, a selected alkaline earth metal detergent comprising a calcium sulfonate detergent and a magnesium sulfonate detergent, an ashless antioxidant comprising alkylated diarylamine and sulfurized olefin, and an ashless dispersant comprising a polyisobutylene succinimide dispersant and a polyisobutylene succinimide borate dispersant, wherein the lubricating composition is substantially zinc-free.

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

[0010] The present disclosure further relates to a method for reducing LSPI in a spark-ignition direct injection internal combustion engine operating under a load having a net mean effective pressure (BMEP) of 10 bar or more at a speed of 3,000 rpm or less, by supplying the engine with a lubricating composition comprising a base oil of lubricating viscosity and an alkyl phosphate amine salt anti-wear agent having at least 30 mole percent of phosphorus atoms in its pyrophosphate structure and contributing 500 ppm to 900 ppm of phosphorus to the lubricating composition, wherein the selected alkaline earth metal detergent comprises calcium sulfonate detergent and magnesium sulfonate detergent, the ashless antioxidant comprises alkylated diarylamine and sulfurized olefin, the ashless dispersant comprises polyisobutylene succinimide dispersant and polyisobutylene succinimide boroate dispersant, and the lubricating composition is substantially zinc-free.

[0011] The disclosure further relates to the use of a lubricating composition comprising a base oil of lubricating viscosity, an ashless phosphorus-containing anti-wear agent, an alkaline earth metal detergent, an ashless antioxidant, and an ashless dispersant, wherein the lubricating composition is further defined as being substantially zinc-free in order to reduce LSPI in a spark-ignition direct-injection internal combustion engine operated under a load having a net mean effective pressure (BMEP) of 10 bar or more 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 anti-wear agent having at least 30 mole percent of phosphorus atoms in its pyrophosphate structure and in an amount that brings 500 ppm to 900 ppm of phosphorus into the lubricating composition, a selected alkaline earth metal detergent including a calcium sulfonate detergent and a magnesium sulfonate detergent, an ashless antioxidant including alkylated diarylamines and sulfurized olefins, and an ashless dispersant including a polyisobutylene succinimide dispersant and a polyisobutylene succinimide borate dispersant, wherein the lubricating composition is substantially zinc-free for use in a spark-ignition direct injection internal combustion engine operating under a load having a net mean effective pressure (BMEP) of 10 bar or more at a speed of 3,000 rpm or less. [Modes for carrying out the invention]

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

[0014] Lubricating viscosity of oil One component of the compositions of this disclosure is a lubricating viscosity oil. As used herein, a lubricating viscosity oil may include natural oils and synthetic oils, oils derived from hydrocracking, hydroturing and hydrofinishing, unrefined oils, refined oils, refined oils, or mixtures thereof. A more detailed description of unrefined oils, refined oils and refined oils is provided in paragraphs

[0054] to

[0056] of International Publication 2008 / 147704 (similar disclosures are provided in U.S. Patent Application 2010 / 197536, see

[0072] to

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

[0058] to

[0059] of International Publication 2008 / 147704, respectively (similar disclosures are provided in U.S. Patent Application 2010 / 197536, see

[0075] to

[0076] ). The citations from both references are incorporated herein. Synthetic oils may also be produced by the Fischer-Tropsch reaction, which is typically a hydrogenated Fischer-Tropsch hydrocarbon or wax. In one embodiment, the oil may be prepared by the Fischer-Tropsch gas liquefaction synthesis procedure, as well as by other gas liquefaction oils.

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

[0016] Lubricating viscosity oils may also be defined as specified in Section 1.3, subheading 1.3, of the April 2008 edition of "Appendix E-API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils." 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 lubricating viscosity oil may be mineral oil, ester or synthetic oil of API Groups I to IV, or a mixture thereof. In another embodiment, the lubricating viscosity oil may be mineral oil, ester or synthetic oil of API Groups II, III, or IV, or a mixture thereof.

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

[0019] In this disclosure, the lubricating oil has a kinematic viscosity of 2.4 m when measured at 100°C. 2 / s~6.4m 2may be / s. In some embodiments, the kinematic viscosity is 4.0 m 2 / s to 5.0 m 2 / s, or 5.2 m 2 / s to 5.8 m 2 / s, or 6.0 m 2 / s to 6.5 m 2 / s. In other embodiments, the kinematic viscosity is 6.2 m 2 / s, or 5.6 m 2 / s, or 4.6 m 2 / s.

[0020] The lubricating composition claimed herein may be in the form of a concentrate and / or a fully formulated lubricant. Where the lubricating composition is in the form of a concentrate (which may be combined with additional oil to form a finished lubricant, in whole or in part), 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 antiwear 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 organophosphorus 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 contains no or substantially no sulfur. In one embodiment, when present, the sulfur content of the phosphorus-containing antiwear agent is an amount such that the weight ratio of sulfur to phosphorus is less than 2:1, or less than 1.75:1.

[0022] In one embodiment, the abrasion-resistant agent containing ashless phosphorus is a phosphite. Suitable phosphites include those having at least one hydrocarbyl group with 3 or more, 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. A phosphite may be represented by the following formula: [ka] In the formula, at least one R may be a hydrocarbyl group containing at least three carbon atoms, and the other R group may 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 may be linear or branched, typically linear, and saturated or unsaturated, typically saturated. In one embodiment, the phosphite is a phosphite according to formula I, where R is C 18 Hydrocarbyl, phenyl portion, C 14 ~C 18 Alkyl or a combination thereof is selected.

[0023] In one embodiment, the abrasion-resistant agent containing no ash phosphorus is C 12~22 It may be a hydrocarbyl phosphite or a mixture thereof, that is, each R may independently be a hydrogen atom or a hydrocarbyl group having 12 to 24 or 14 to 20 carbon atoms, typically 16 to 18 carbon atoms. Typically, C 12~22 Hydrocarbyl phosphite is C 16~18 Contains hydrocarbyl phosphite. 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. In another embodiment, the phosphite is C 3~8 It may be a hydrocarbyl phosphite or a mixture thereof, that is, each R may independently be a hydrogen atom 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 phosphites.

[0024] The phosphites used herein may further contain phosphite esters. The phosphite esters include the reaction product of (a) monomer phosphite or an ester thereof and (b) a first alkylenediol (i) having at least two alkylenediols, i.e., two hydroxyl groups in a 1,4, 1,5, or 1,6 relationship, and a second alkylenediol (ii) which is an alkyl-substituted 1,3-propylenediol, wherein one or more of its 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-propylenediol is 5 or 6 to 12, wherein the relative molar amounts of monomer phosphite or an ester thereof (a) and alkylenediol (b) are in a ratio of 0.9:1.1 to 1.1:0.9, and the relative molar amounts of the first alkylenediol (i) and alkyl-substituted 1,3-propylenediol (ii) are in a ratio of 30:70 to 65:35.

[0025] The phosphites used herein may further contain sulfur-containing phosphites. A suitable sulfur-containing phosphite is given by formula: [ka] Examples of things that can be represented are: In the formula, R 1 and R 2Each of these is independently either a hydrocarbyl group with 3 to approximately 12 carbon atoms, or 6 to 8 carbon atoms, or [ka] It is a base represented by, Alternatively, in the formula, R 1 and R 2 It, together with adjacent O and P atoms, forms a ring containing 2 to 6 carbon atoms, R 3 R is a hydrogen or methyl group, 4 R is an alkylene group with 2 to 6 carbon atoms, 5 n is either hydrogen or a hydrocarbyl group with 1 to approximately 12 carbon atoms, and n is 1 or 2.

[0026] In another embodiment, the ashless phosphorus-containing abrasion resistant 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. Therefore, for example, "(thio)phosphate" includes both phosphate compounds and thiophosphate compounds.

[0027] In one embodiment, the (thio)phosphate is a dithiophosphate ester. A suitable dithiophosphate ester can be formed by the reaction of dithiophosphate, 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 its esters, methacrylic acid or its esters, itaconic acid or its esters, fumaric acid or its esters, and maleic acid, its anhydride or its esters.

[0028] Examples of (thio)phosphates include phosphorus-containing amide esters, which can be prepared by the reaction of phosphoric acid (e.g., dithiophosphate) with an unsaturated amide. Examples of unsaturated amides include acrylamide, N,N'-methylenebisacrylamide, methacrylamide, and crotonamide. The reaction product of the phosphate and the unsaturated amide may be further reacted with a binding or coupling compound such as formaldehyde or paraformaldehyde. Phosphorus-containing amides are known in the art and are disclosed in U.S. Patents 4,670,169, 4,770,807, and 4,876,374, which are incorporated by reference to the disclosures of phosphorus amides and their preparations.

[0029] In another embodiment, the ashless phosphorus-containing abrasion resistant agent may be a (thio)phosphate amine salt. In one embodiment, the (thio)phosphate amine salt is an amine alkylthiophosphate, where the alkylthiophosphate reacts with an epoxide or a polyhydric alcohol (e.g., glycerol). The reaction product may be used alone or further reacted with a phosphate, anhydride, or lower ester. The epoxide is generally an aliphatic epoxide or a styrene oxide. Examples of useful epoxides include ethylene oxide, propylene oxide, butene oxide, octen oxide, dodecene oxide, and styrene oxide, with ethylene oxide and propylene oxide being preferred. The polyhydric alcohol may be an aliphatic glycol having 1 to about 12, about 2 to about 6, or 2 or 3 carbon atoms. The glycol includes ethylene glycol and propylene glycol. Alkylthiophosphates, glycols, epoxides, inorganic phosphorus reagents, and methods for reacting them are described in U.S. Patents No. 3,197,405 and No. 3,544,465, which are incorporated herein by reference.

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

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

[0032] Substantially sulfur-free alkylphosphateamine salts that exist in pyrophosphate form (sometimes called POP structure) are partially of the following formulas (I) and / or (II): [ka] It is represented as follows. Formula (V) represents a partially neutralized phosphorus salt, and formula (VI) represents a fully neutralized salt. Both of the two hydroxyhydrogen atoms in the initially formed phosphate structure are acidic enough to be neutralized by the amine, and as a result, formula (VI) may prevail if a stoichiometrically sufficient amount of amine is present. The actual degree of neutralization, i.e., the degree of salting out of the -OH group 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 can be determined or calculated based on the amount of amine added to the phosphate ester mixture. Variants of these substances may exist, such as variants of formula (V) or formula (VI), where the -OH group in formula (V) is replaced by another -OR 1 Replaced by the base, or one or more -OR 1 The group is replaced by an -OH group, or R 1 The group is a phosphorus-containing group (i.e., terminal R 1 It is replaced by a third phosphorus structure (instead of the base). Exemplary variants may include the following: [ka]

[0033] The structures of formulas (V) and (VI) are shown as completely sulfur-free species, in that the phosphorus atom is bonded to oxygen rather than a sulfur atom. However, the 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 following general structure: [ka] It can be distinguished from orthopyrrophosphate, This can also exist in the above quantities, at will.

[0035] In equations (V) and (VI), each R 1These are, independently, alkyl groups having 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, alkyl groups may 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 having 6, 7, 8, 9, 10, 11, or 12 carbon atoms and their isomers. In some embodiments, alkyl groups may have a methyl branch at the α-position of the group, one example being the 4-methyl-2-pentyl (also known as 4-methylpentyl-2-yl) group.

[0036] Such alkyl (including cycloalkyl) groups are typically produced by the reaction of the corresponding alcohol or multiple alcohols with phosphorus pentoxide (referred to as P2O5 herein, but a more likely structure is P4O 10 (It is recognized that this can be expressed as follows). Typically, 2 to 3.1 moles of alcohol are produced per mole of P2O5, resulting in a mixture of partial esters such as mono and diesters with orthophosphate structures and diesters with pyrophosphate structures. [ka]

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

[0038] The reaction conditions and reactants can be selected to be favorable to the formation of pyrophosphate esters and relatively unfavorable to the formation of orthophosphate monoesters and orthophosphate diesters. The use of secondary alcohols rather than primary alcohols has been found to be favorable to the formation of pyrophosphate structures. Preferred synthesis temperatures include 30–60°C, 35–50°C, 40–50°C, 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 the initial mixing of the components may be desirable. Especially when the temperature is above 60°C, it may be desirable to avoid overheating the reaction mixture or to stop heating when 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, 61°C, or 60°C. Preferred conditions may also include the removal of water from the outside. The progress of the reaction and the relative amounts of various phosphorus species can be determined by infrared spectroscopy and 31 P or 1 It can be measured by spectroscopic methods known to those skilled in the art, such as 1H NMR spectroscopy.

[0039] Pyrophosphate esters can be isolated from orthoesters as needed, but it is also possible, and commercially preferable, to use the reaction mixture without separating the components.

[0040] Pyrophosphate phosphate esters or mixtures of phosphate esters react with amines to form amine salts. The amine is R 2 It can be expressed as 3N, where each R 2 R is independently a hydrogen atom, a hydrocarbyl group, an ester-containing group, or an ether-containing group, provided that at least one R 2 The group is a hydrocarbyl group, an ester-containing group, or an ether-containing group (i.e., not NH3). Suitable hydrocarbylamines include primary amines having 1 to 18 carbon atoms or 3 to 12 or 4 to 10 carbon atoms (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 dodecylamines and 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 Products available from Chemicals, Chicago, Ill (such as Armeen® C, Armeen® O, Armeen® OL, Armeen® T, Armeen® HT, Armeen® S, and Armeen® SD), where the letter designations relate to aliphatic groups such as coco, oleyl, talo, or stearyl groups.

[0041] Examples of secondary amines that can be used include dimethylamine, diethylamine, dipropylamine, dibutylamine, diamylamine, dihexylamine, diheptylamine, methylethylamine, ethylbutylamine, bis-2-ethylhexylamine, N-methyl-1-aminocyclohexane, Armeen® 2C, and ethylamylamine. Secondary amines may also 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 also be used.

[0043] Examples of amine mixtures 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 is "Primene® 81R" or "Primene® JMT". Primene® 81R and Primene® JMT (both manufactured and sold by Rohm & Haas) are, respectively, C 11 ~C 14 A mixture of tertiary alkyl and primary amines and C 18 ~C 22 It may be a mixture of tertiary alkyl and 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 oxygen atoms of the ester group may be replaced by sulfur, but typically the sulfur atoms may not be present. N-substituted γ-aminoesters are [ka] It can be represented by, Furthermore, N-substituted δ-aminoesters are [ka] It can be represented by [this].

[0045] One or more further 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 therefore, in a particular embodiment, the formula [ka] This brings forth a group of substances represented by R and R 4 X is defined as follows, where X is O or S (in one embodiment, O), and R 5 is hydrogen, a hydrocarbyl group, or -C(=O)-R 6 It may also be a group represented by, where R 6 is hydrogen, alkyl group, or -X'-R 7 In the formula, X' is either O or S, and R 7 This is a hydrocarbyl group with 1 to 30 carbon atoms. That is, the substituent at the β position of the chain may include an ester, thioester, carbonyl, or hydrocarbyl group. 5 -C(=O)-R 6 In that case, the structure is, [ka] It can be represented by [this]. It is understood that this includes similar structures for δ-aminoesters, for example, [ka] It is possible. R 6 ga-X'-R 7 In that case, it will be clear that the substance is a substituted succinate ester or thioester. In one embodiment, specifically, the substance may be a methyl succinate diester having an amine substitution on the methyl group. 4 Base and R 7 The bases may be the same or different. In certain embodiments, they may be independent of R 4 It may have 1 to 30 or 1 to 18 carbon atoms, as described below. In certain embodiments, this material may have [ka] It can be represented by its structure. In certain embodiments, the substance is or comprises 2-((hydrocarbyl)-aminomethylsuccinate dihydrocarbyl ester (which may also be referred to as dihydrocarbyl 2-((hydrocarbyl)aminomethylsuccinate).

[0046] In the above structure, the hydrocarbyl substituent R on the amine nitrogen may include a hydrocarbyl group of at least three carbon atoms that has branching at the 1st or 2nd (i.e., α or β) position of the hydrocarbyl chain (which should not be confused with the α or β position of the ester group). Such a branched hydrocarbyl group R is a partial formula [ka] It can be represented by, In the formula, the bond on the right represents the bond to the nitrogen atom. In this substructure, n is 0 or 1, and R 1 R is a hydrogen or hydrocarbyl group, 2 and R3 The groups may be hydrocarbyl groups independently, or together they may form a carboxylic acid structure. The hydrocarbyl groups may be aliphatic, alicyclic, aromatic, or a mixture thereof. When n is 0, the branching is at the 1st or αth position of the group. When n is 1, the branching is at the 2nd or βth position. The above R 4 If n is methyl, then n may be 0 in some embodiments. [ka] Of course, branching can occur at both the first and second positions. Connection to a cyclic structure can be considered branching. [ka] (Types of 1- or α branching)

[0047] Therefore, the branched hydrocarbyl substituent R on the amine nitrogen may include groups such as isopropyl, cyclopropyl, sec-butyl, isobutyl, t-butyl, 1-ethyl-propyl, 1,2-dimethylpropyl, neopentyl, cyclohexyl, 4-heptyl, 2-ethyl-1-hexyl (commonly called 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 is R 4 It 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 may 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, which is a hydrocarbyl substituent on nitrogen, may often have branching at position 1. In other embodiments, R 4The group may be an ether-containing group. For example, it may be an ether-containing group or a polyether-containing group that may contain, for example, 2 to 120 carbon atoms along with an oxygen atom representing an ether functional group.

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

[0050] In one embodiment, the amine is structure [ka] It can be expressed as, In the formula, R 6 and R 7 R is an alkyl group with 1 to approximately 6 carbon atoms, 8 and R 9 These are alkyl groups with 1 to approximately 12 carbon atoms, independently of each other.

[0051] The N-hydrocarbyl-substituted γ-aminoester or γ-aminothioester materials disclosed herein can typically be prepared by Michael addition of a primary amine having the branched hydrocarbyl group described above to an ethylenically unsaturated ester or thioester of the same type as described above. In this example, the ethylenically unsaturated portion is between the β-carbon and γ-carbon atoms of the ester. Therefore, this reaction can be performed, for example, [ka] This could happen, In the formula, X and the R group 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 R can be hydrogen or a hydrocarbyl group, 2 and R 3 The groups can be independently hydrocarbyl groups or together form a carbocyclic structure, where X is O or S, and R 4 It can be a hydrocarbyl group with 1 to 30 carbon atoms, and R 5 is hydrogen, hydrocarbyl group, or -C(=O)-R 6 It can be a group represented by, where R 6 is hydrogen, alkyl group, or -X'-R 7 And in the formula, X' is either O or S, and R 7 n is a hydrocarbyl group with 1 to 30 carbon atoms. In one embodiment, the amine reactant is a tertiary hydrocarbyl (e.g., t-alkyl) rather than a primary amine, i.e., n is not 0, but R 1 , R 2 , and R 3 These are each hydrocarbyl groups.

[0052] The amine capable of reacting to form the above-mentioned Michael addition product may be a primary amine, and the resulting product is a secondary amine having the above-mentioned branched R substituent and with nitrogen bonded to the remainder of the molecule.

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

[0054] Details of N-substituted γ-aminoesters and their synthesis can be found in International Publication No. 2014 / 074335, Lubrizol, May 15, 2014. Details of N-substituted δ-aminoesters 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] Any type of amine reacts to neutralize the acidic groups on the phosphate ester components, including the pyrophosphate esters and any orthophosphate esters that may be present.

[0056] In one embodiment, the phosphate-free abrasion resistant agent is an alkyl phosphate amine salt. Amine phosphates can be derived from mono- or dihydrocarbyl phosphates (typically alkyl phosphates), or mixtures thereof. The alkyl of mono- or dihydrocarbyl phosphates may include linear or branched alkyl groups with 3 to 36 carbon atoms. The hydrocarbyl group of linear or branched hydrocarbyl phosphates may contain 4 to 30 or 8 to 20 carbon atoms. Examples of suitable hydrocarbyl groups for hydrocarbyl phosphates 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) phosphates.

[0057] Suitable examples of primary amines include ethylamine, propylamine, butylamine, 2-ethylhexylamine, octylamine, and dodecylamine, as well as aliphatic amines such as n-octylamine, n-decylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, and oleyamine. 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 designations relate to aliphatic groups such as coco, oleyl, tallow, or stearyl groups.

[0058] The compositions disclosed herein may also contain amine dialkyldithiophosphates. Examples of suitable amine (or ammonium) dialkyldithiophosphates include those of formula: [ka] Salt is one example, In the formula, R 8 and R 9 These are independently hydrocarbyl groups containing 3 to 30 or 3 to 20, 3 to 16, or 3 to 14 carbon atoms, and are formed by the reaction of phosphorus pentasulfide (P2S5) with an alcohol or phenol, according to formula: [ka] It can be easily obtained by forming the corresponding O,O-dihydrocarbyl phosphorodithio acid.

[0059] This reaction involves mixing 4 moles of alcohol or phenol with 1 mole of phosphorus pentasulfide at a temperature of 20°C to 200°C. Hydrogen sulfide is liberated in this reaction. This acid is then reacted with a basic amine (or ammonium) compound to form a salt.

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

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

[0062] Such amine salts are often called amine dialkyldithiophosphates or simply amine dithiophosphates. They are well known and readily available to those skilled in the art of lubricant formulations. Further 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 contain primary zinc dialkyldithiophosphates. In some embodiments, the compositions of the present invention contain secondary zinc dialkyldithiophosphates. In some embodiments, the compositions of the present invention contain 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 (by weight) of primary and secondary dialkyldithiophosphates is at least 1:1, or at least 1:1.2, or at least 1:1.5, 1:2, or 1:10. In some embodiments, the amine phosphate is a mixture of a primary dialkyldithiophosphate and a secondary dialkyldithiophosphate, wherein the secondary dialkyldithiophosphate makes up at least 50% by weight basis of the primary, or more specifically, at least 60, 70, 80%, or even 90% by weight basis of the primary.

[0063] In one embodiment, the alkyl phosphate amine salt is an alkyl dithiophosphate amine salt. Zinc dialkyldithiophosphate is known in the art. The amine dithiophosphate may include a linear or branched alkyl group containing 3 to 20 carbon atoms, 3 to 12 carbon atoms, or 4 to 8 carbon atoms.

[0064] Examples of dithiophosphates that may be amine salts include isopropylmethylamyl 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 anti-wear agent may be present in the lubricating composition in an amount of 0.1 to 1.5% by weight. In another embodiment, the ashless phosphorus-containing anti-wear agent may be present in the lubricating composition in an amount of 0.3 to 1.2% by weight. In yet another embodiment, the ashless phosphorus-containing anti-wear agent may be present in the lubricating composition in an amount of 0.5 to 1.1% by weight. In yet another embodiment, the ashless phosphorus-containing anti-wear agent may be present in the lubricating composition in an amount of 0.6 to 0.9% by weight.

[0066] In certain embodiments, the amount of ashless phosphorus-containing anti-wear agent is defined by the amount of phosphorus that can be introduced into the lubricating composition. In such embodiments, the ashless phosphorus-containing anti-wear agent is present in an amount that introduces 500 to 900 ppm of phosphorus into the lubricating composition. In other embodiments, the ashless phosphorus-containing anti-wear agent is present in an amount that introduces 550 to 850 ppm of phosphorus into the lubricating composition. In other embodiments, the ashless phosphorus-containing anti-wear agent is present in an amount that introduces 600 to 825 ppm of phosphorus into the lubricating composition. In other embodiments, the ashless phosphorus-containing anti-wear agent is present in an amount that introduces 650 to 800 ppm of phosphorus into the lubricating composition. In other embodiments, the ashless phosphorus-containing anti-wear agent is present in an amount that introduces 700 to 800 ppm of phosphorus into the lubricating composition.

[0067] Alkaline earth metal cleaner The lubricating compositions disclosed herein further comprise an alkaline earth metal detergent. Suitable alkaline earth metal detergents include metal perbasic detergents.

[0068] Metal overbase detergents, also called overbase detergents, metal-containing overbase detergents, or superbase salts, are characterized by a metal content exceeding the amount required for stoichiometric neutralization of the metal and certain acidic organic compounds (i.e., substrates that react with the metal). Overbase detergents may contain one or more of the following: non-sulfur-containing phenates, sulfur-containing phenates, sulfonates, salicylates, and mixtures thereof.

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

[0070] Metal-containing detergents may further include a “hybrid” detergent formed by a mixed surfactant system containing phenate and / or sulfonate components, such as phenate-salicylate, sulfonate-phenate, sulfonate-salicylate, or sulfonate-phenate-salicylate, as described in, for example, U.S. Patents 6,429,178, 6,429,179, 6,153,565, and 6,281,179. For example, when using a hybrid sulfonate / phenate detergent, the amount of this hybrid detergent is considered equivalent to the amounts of separate phenate and sulfonate detergents introducing similar amounts of phenate soap and sulfonate soap, respectively. Overbasic phenates and salicylates typically have a total base number of 180 to 450 TBN. Overbasic sulfonates typically have a total base number of 250 to 600, or 300 to 500. Over-basic cleaning agents are known in this field.

[0071] Alkylphenols are often used as components in and / or as building blocks of overbasic detergents. Alkylphenols can be used to prepare phenates, salicylates, salixalates, or saligenin detergents or mixtures thereof. Suitable alkylphenols include para-substituted hydrocarbylphenols. The hydrocarbyl group can be a linear or branched aliphatic group with 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 overbasic detergent is prepared from alkylphenols or mixtures thereof that do not contain or substantially contain p-dodecylphenol (i.e., contain less than 0.1% by weight). In one embodiment, the lubricating composition of the present invention contains less than 0.3% by weight of alkylphenol, less than 0.1% by weight of alkylphenol, or less than 0.05% by weight of alkylphenol.

[0072] The overbasic metal-containing detergent may be an alkali metal salt or an alkaline earth metal salt. In one embodiment, the overbasic detergent may be a sodium salt, calcium salt, magnesium salt of phenate, sulfur-containing phenate, sulfonate, salixalate, and salicylate, or a mixture thereof. In one embodiment, the overbasic detergent is a calcium detergent, a magnesium detergent, or a mixture thereof. In one embodiment, the overbasic calcium detergent may be present in an amount that brings to the lubricating composition at least 500 ppm by weight of calcium and 3000 ppm by weight or less of calcium, or at least 1000 ppm by weight of calcium, or at least 2000 ppm by weight of calcium, or 2500 ppm by weight or less of calcium. In one embodiment, the overbasic detergent may be present in an amount that brings to the lubricating composition 500 ppm by weight or less, or 330 ppm by weight or less, or 125 ppm by weight or less, or 45 ppm by weight or less of magnesium. In one embodiment, the lubricating composition is essentially magnesium-free (i.e., contains less than 10 ppm of magnesium) from the overbasic detergent. In one embodiment, the overbasic detergent may be present in an amount that results in at least 200 ppm by weight of magnesium, or at least 450 ppm by weight of magnesium, or at least 700 ppm by weight of magnesium in the lubricating composition. In one embodiment, both a calcium-containing detergent and a magnesium-containing detergent may be present in the lubricating composition. The calcium detergent and the magnesium detergent 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 overbasic detergent is sodium-free or substantially sodium-free.

[0073] In one embodiment, the sulfonate detergent may be a linear alkylbenzene sulfonate detergent having a metal ratio of at least 8, as described in paragraphs

[0026] to

[0037] of U.S. Patent Publication No. 2005 / 065045 (and granted as U.S. Patent No. 7,407,919). Linear alkylbenzene sulfonate detergents may be particularly useful in helping to improve fuel economy. The linear alkyl group may be bonded to the benzene ring at any position along the linear chain of the alkyl group, but is often bonded at the 2nd, 3rd, or 4th position of the linear chain, and in some cases mainly at the 2nd position, resulting in a linear alkylbenzene sulfonate detergent.

[0074] Salicylate detergents and overbasic salicylate detergents can be prepared in at least two different ways. Carbonylation (also called carboxylation) of p-alkylphenols is described in many references, including U.S. Patent No. 8,399,388. Overbasication after carbonylation can form overbasic salicylate detergents. Suitable p-alkylphenols include those having linear and / or branched hydrocarbyl groups of 1 to 60 carbon atoms. Salicylate detergents may further be prepared by alkylation of salicylic acid followed by overbasication, as described in U.S. Patent No. 7,009,072. Salicylate detergents thus prepared 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 overbasic detergent of the present invention is a salicylate detergent. In one embodiment, the salicylate detergent of the present invention does not contain unreacted p-alkylphenol (i.e., it 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 cleaner is selected from calcium, magnesium, or a mixture thereof. In one embodiment, the alkaline earth metal cleaner is a calcium sulfonate cleaner. In another embodiment, the alkaline earth metal cleaner is a magnesium sulfonate cleaner. In one embodiment, the alkaline earth metal cleaner is a mixture of two or more alkaline earth metal cleaners. In embodiments where the alkaline earth metal cleaner is a mixture, the mixture may also contain a calcium sulfonate cleaner and a magnesium sulfonate cleaner.

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

[0077] Ash-free antioxidant The lubricating compositions disclosed herein further comprise ashless antioxidants. Examples of ashless antioxidants include 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 bonded to the amine nitrogen. Examples of arylamines include N-alkylnaphthylamines, which may have one or two N-alkyl groups, i.e., the nitrogen group is monosubstituted or disubstituted. In one embodiment, the nitrogen group is mainly monosubstituted. The N-alkyl group may be acyclic, cyclic, or alicyclic. The acyclic alkyl group may be branched.

[0079] Diarylamines or alkylated diarylamines may be phenyl-α-naphthylamine (PANA), alkylated diphenylamine, alkylated phenylnaphthylamine, or mixtures thereof. Examples of alkylated diphenylamines include di-nonylated diphenylamine, nonyldiphenylamine, octyldiphenylamine, di-octylated diphenylamine, di-decylated diphenylamine, decyldiphenylamine, and mixtures thereof. In one embodiment, the diphenylamine may include nonyldiphenylamine, dinonyldiphenylamine, octyldiphenylamine, dioctyldiphenylamine, or mixtures thereof. In one embodiment, the alkylated diphenylamine may include nonyldiphenylamine or dinonyldiphenylamine. Examples of alkylated diarylamines include octyl, dioctyl, nonyl, dinonyl, decyl, or didecylphenylnaphthylamine.

[0080] The diarylamine of the present invention also has the following formula: [ka] It can be represented by, In the formula, R1 and R2 are parts that bond together with the carbon atoms to which they are bonded to form a 5-membered, 6-membered, or 7-membered ring (such as a carbocyclic ring or a cyclic hydrocarbyl ring); R3 and R4 are independently hydrogen, a hydrocarbyl group, or parts that bond together with the carbon atoms to which they are bonded to form a 5-membered, 6-membered, or 7-membered ring (such as a carbocyclic ring or a cyclic hydrocarbyl ring); R5 and R6 are independently hydrogen, a hydrocarbyl group, or parts that bond together with the carbon atoms to which they are bonded to form a ring, or parts that represent zero carbon or direct inter-ring bonds (typically hydrocarbyl parts); 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 is given by formula: [ka] It can be expressed as, In the formula, R3 and R4 are defined as described above.

[0083] In another embodiment, the diarylamine compound is given by the general formula: [ka] Including those that have, In the formula, R7 is defined as above, R5 and R6 may independently be hydrogen, a hydrocarbyl group, or together form a ring such as dihydroacridane, n=1 or 2, and Y and Z independently represent carbon or heteroatoms such as N, O and S.

[0084] In a particular embodiment, the diarylamine compound is of the formula: [ka] This includes those.

[0085] In one embodiment, the diarylamine is given by formula: [ka] It is a dihydroacridan derivative, In the formula, 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 direct (or zero-carbon) linkages between aryl rings. The result is given by formula: [ka] It is carbazole, In the formula, R1, R2, R3, and R4 are defined as described above.

[0087] Diarylamine antioxidants may be present in the lubricating composition in amounts of 0.1% to 10% by weight, 0.35% to 5% by weight, or even 0.5% to 2% by weight, or 0.1 to 2.1% by weight or 0.2 to 1.8% by weight, based on the total weight of the lubricating composition.

[0088] The phenolic antioxidant may be a simple alkylphenol, a hindered phenol, or a conjugated phenol compound.

[0089] Hindered phenol antioxidants often contain secondary and / or tertiary butyl groups as sterically hindering groups. The phenol group may be further substituted with a hydrocarbyl group (typically a linear or branched alkyl group) and / or a crosslinking group bonded 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-hydroxylphenyl)propanoate. In one embodiment, the hindered phenol antioxidant may be an ester, for example, Irganox® L-135 from Ciba.

[0090] The bound phenol often contains two alkylphenols that combine with 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] The phenols of the present invention also include polyhydric aromatic compounds and their derivatives. Examples of suitable polyhydric aromatic 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 includes a hindered phenol. In another embodiment, the hindered phenol is derived from 2,6-di-tertbutylphenol.

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

[0094] Sulfide olefins are well-known commercial materials, and those that are substantially nitrogen-free, i.e., do not contain nitrogen functional groups, are readily available. The olefin compounds that can be sulfidized are actually quite diverse. They contain at least one olefin double bond, defined as a non-aromatic double bond, i.e., one that links two aliphatic carbon atoms. These materials generally have sulfide bonds containing 1 to 10, for example, 1 to 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 at least two antioxidants are present in an amount of at least 0.1 weight percent each, and the total amount of ashless antioxidants is 0.5 to 5 weight percent.

[0096] The ash-free antioxidant may be present in an amount of 0.1 to 2.1% by weight, or 0.2 to 1.8% by weight, 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 to 1.3% by weight of an alkylated diarylamine and 0.1 to 0.5% by weight of a 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 succinate ester, an amide, or an ester-amide, or a mixture thereof. In one embodiment, the dispersant may be a succinimide borate dispersant. In one embodiment, the dispersant may be a succinimide borate dispersant. In one embodiment, the dispersant may exist as a single dispersant. In another embodiment, the dispersant may exist as a mixture of two or three different dispersants.

[0099] The succinimide dispersant may be derived from aliphatic polyamines or mixtures thereof. The aliphatic polyamine may be an aliphatic polyamine such as ethylene polyamine, propylene polyamine, butylene polyamine, or a mixture 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 ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyamine distillation residue, 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), derivatives 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 polyetheramine or a derivative of a polyether polyamine. A typical polyetheramine compound will contain at least one ether unit and will be chain-terminated at at least one amine moiety. Polyether polyamines can be based on polymers derived from C2-C6 epoxides such as ethylene oxide, propylene oxide, and butylene oxide. An example of a polyether polyamine is marketed under the Jeffamine® brand and is commercially available from Huntsman Corporation.

[0102] The dispersant may be an N-substituted long-chain alkenyl succinimide. An example of an N-substituted long-chain alkenyl succinimide is polyisobutylene succinimide. Typically, the polyisobutylene derived from polyisobutylene succinic anhydride has a number average molecular weight of 350-5000, or 550-3000, or 750-2500. Succinimide dispersants and their preparations are described, for example, in U.S. Patents 3,172,892, 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170, and 3,467. This is disclosed in Patent Nos. 668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, Re26,433, 6,165,235, 7,238,650, and European Patent No. 0355895(B1).

[0103] Dispersants can also be post-treated by conventional methods involving reaction with a variety of agents. These include, among others, boron compounds, urea, thiourea, dimercaptothiadiazole, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydride, maleic anhydride, nitriles, epoxides, and phosphorus compounds.

[0104] The dispersant 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 borate. In one embodiment, the borooxidant is boric acid, which may be used alone or in combination with other borooxidants. Methods for preparing borated dispersants are known in the art. The borooxidant dispersant may be prepared to contain 0.1% to 2.5% by weight of boron, or 0.1% to 2.0% by weight of boron, or 0.2% to 1.5% by weight of boron, or 0.3% to 1.0% by weight of boron.

[0105] Suitable polyisobutylenes for use in succinimide dispersants may be those formed from polyisobutylene or highly reactive polyisobutylene having a terminal vinylidene content of at least about 50 mol%, particularly about 60 mol%, and especially about 70 mol% to about 90 mol%, or more than 90 mol%. Suitable polyisobutenes may include those prepared using a BF3 catalyst. In one embodiment, the borooxide 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 / can be obtained from the reaction of succinic anhydride by an "ene" reaction or a "thermal" reaction, by a process 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 succinimide having a carbocyclic ring present in less than 50 mol%, or 0-30 mol%, or 0-20 mol%, or 0 mol% of the dispersant molecule. The "ene" reaction may have a reaction temperature of 180°C-300°C, or 200°C-250°C, or 200°C-220°C.

[0107] Dispersants may also be obtained / obtainable from chlorine-assisted processes, often involving Diels-Alder chemistry, which lead to the formation of carbocyclic bonds. This process is known to those skilled in the art. Chlorine-assisted processes can produce dispersants that are polyisobutylene succinimides having carbocyclic bonds present in 50 mol% or more, or 60–100 mol%, of the dispersant molecules. Both thermal and chlorine-assisted processes are described in detail in U.S. Patent 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-borooxidizing or borooxidizing dispersants. When a mixture of dispersants is used, there may be two to five, two to three, or two dispersants.

[0109] The polyolefin dispersant may include a polyalphaolefin (PAO) containing a dispersant selected from the group consisting of polyalphaolefin succinimide, polyalphaolefin succinamide, polyalphaolefin acid ester, polyalphaolefin oxazoline, polyalphaolefin imidazoline, polyalphaolefin succinamide imidazoline, and combinations thereof.

[0110] Polyalphaolefins (PAOs), useful as raw materials for 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. In the commercial production of PAOs, typically, raw materials containing a mixture of two or more of the aforementioned monomers and other hydrocarbons are used. PAOs can take the form of dimers, trimers, tetramers, polymers, and other materials.

[0111] PAO can be reacted with maleic anhydride (MA) to form polyalphaolefin succinic anhydride (PAO-SA), and then the anhydride can be reacted with one or more of polyamines, amino alcohols, and alcohol / polyols to form polyalphaolefin succinimide, polyalphaolefin succinamide, polyalphaolefin succinic acid ester, polyalphaolefin oxazoline, polyalphaolefin imidazoline, polyalphaolefin-succinamide-imidazoline, and mixtures thereof.

[0112] Another class of ashless dispersants are Mannich bases. These 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. Patent No. 3,634,515.

[0113] Useful nitrogen-containing dispersants include the products of the 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 trisubstituted or disubstituted phenol. In some embodiments, the phenol may be a monosubstituted phenol. The substitution may be at the ortho, and / or meta, and / or para positions. To form the Mannich product, the molar ratio of the aldehyde to the 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, and more preferably 1:1-2:1. To form a 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, for example at least 1.8:1, and 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. Preferably it may be 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 polyisobutylene succinimide borate dispersant. In one embodiment, the ashless dispersant is present in the lubricating composition in an amount of 1 to 6% by weight, or 2 to 5% by weight, or 2.5 to 4.5% by weight. In one embodiment, the ashless dispersant comprises a mixture of 0.8 to 1.6% by weight of a boron-free polyisobutylene succinimide dispersant and 1.8 to 3.1% by weight of a polyisobutylene borate dispersant. In another embodiment, one or more of the boron-free polyisobutylene succinimide dispersant and the polyisobutylene succinimide borate dispersant are produced from a direct alkylation process.

[0115] The lubricating compositions disclosed herein are substantially zinc-free. As used herein, “substantially zinc-free” means that the lubricating compositions may contain small amounts of the described 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 composition is zinc-free, which means that the lubricating composition contains 0 ppm of zinc.

[0116] Other additives The lubricating compositions of this 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, foam inhibitors, demulsifiers, pour point depressants, seal swelling 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 contains a package of multiple performance-enhancing additives.

[0117] Suitable dispersant viscosity modifiers include functionalized polyolefins, such as ethylene-propylene copolymers functionalized with maleic anhydride and acylating agents such as amines, polymethacrylates functionalized with amines, or esterified styrene-maleic anhydride copolymers reacted with amines. A more detailed description of dispersant viscosity modifiers is disclosed in International Publication No. 2006 / 015130, or U.S. Patents No. 4,863,623, No. 6,107,257, No. 6,107,258, and No. 6,117,825. In one embodiment, dispersant viscosity modifiers may include those described in U.S. Patent No. 4,863,623 (see lines 15 to 52 in column 2) or International Publication No. 2006 / 015130 (page 2, paragraph

[0008] and examples of preparations 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 dialkyldithiophosphate, molybdenum dithiocarbamate, amine salts of molybdenum compounds, and mixtures thereof. The molybdenum compound can provide the lubricating composition with molybdenum in concentrations of 0 to 1000 ppm, 5 to 1000 ppm, 10 to 750 ppm, 5 ppm to 300 ppm, or 20 ppm to 250 ppm.

[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, for example, condensation products of carboxylic acids and polyalkylene-polyamines; amine salts of alkyl phosphates; fatty alkyl tartrates; fatty alkyl tartrate imides; or fatty alkyl tartramides. As used herein, the term "fatty" may mean having a linear alkyl group of C8-22.

[0120] The friction modifier may also encapsulate materials such as sulfurized fatty compounds and olefins, molybdenum dialkyl dithiophosphates, 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 tartramides; and fatty alkyl tartramides. The friction modifier may be present in the lubricating composition at a concentration of 0% to 6% by weight, or 0.05% to 4% by weight, or 0.1% to 2% by weight.

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

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

[0124] The lubricating composition may further contain metal deactivators such as derivatives of benzotriazole (typically toltriazole), dimercaptothiadiazole derivatives, 1,2,4-triazole, benzimidazole, 2-alkyldithiobenzimidazole, or 2-alkyldithiobenzothiazole; antifoaming agents such as copolymers of ethyl acrylate and 2-ethylhexyl acrylate, and copolymers of ethyl acrylate, 2-ethylhexyl acrylate, and vinyl acetate; deemulsifiers including trialkyl phosphate, polyethylene glycol, polyethylene oxide, polypropylene oxide, and (ethylene oxide-propylene oxide) polymers; and pour point depressants such as esters of maleic anhydride-styrene, polymethacrylate, polyacrylate, or polyacrylamide.

[0125] The pour point depressants that may be useful in the compositions of the present invention further include polyalphaolefin, maleic anhydride-styrene ester, poly(meth)acrylate, polyacrylate, or polyacrylamide.

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

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

[0128] This lubricating composition can be used to reduce or eliminate low-speed premature ignition ("LSPI") in an engine. In one embodiment, the lubricating composition disclosed herein can be used in a manner that reduces LSPI in a direct-injection engine by supplying the lubricating composition to the engine. LSPI events can be catastrophic. Therefore, a significant reduction, or even elimination, of LSPI events during normal or sustained operation of a direct-fuel injection engine is desirable.

[0129] LSPI events can occur when a direct injection engine is operated at a speed of 3,000 rpm or less and under a load of 10 bar or more with a net mean effective pressure (BMEP). An LSPI event can consist of one or more LSPI combustion cycles, generally occurring consecutively or alternating with normal combustion cycles in between. While not bound by any particular theory, LSPI may result from the combustion of oil droplets that may accumulate in the piston's upper land clearance volume, or in the piston's ring land and ring groove clearances, or droplets of an oil-fuel mixture, or a combination thereof. Due to abnormal piston ring movement, lubricating oil may move from below the oil control ring to the piston top land region. Under low-speed, high-load conditions, in-cylinder pressure dynamics (compression and ignition pressure) can differ significantly from in-cylinder pressure at low loads, due to significantly delayed combustion phasing and high boost and peak compression pressures, which can particularly affect ring dynamics.

[0130] Under the aforementioned loads, LSPI can be accompanied by subsequent detonation and / or severe engine knock, potentially causing serious engine damage very quickly (often within 1 to 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 mitigating an LSPI event, comprising supplying an engine with a lubricant composition disclosed herein.

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

[0132] The aluminum surface may be composed of an aluminum alloy that is eutectic or hypereutectic aluminum alloy (such as one 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] Internal combustion engines may be fitted with exhaust control systems or turbochargers. Examples of exhaust control systems include diesel particulate filters (DPFs) or systems using selective catalytic reduction (SCR).

[0134] The internal combustion engine of this invention is distinct from a gas turbine. In an internal combustion engine, individual combustion events are converted from linear reciprocating forces into rotational torque via rods and a crankshaft. In contrast, in a gas turbine (sometimes called a jet engine), the continuous combustion process generates rotational torque continuously without conversion, and can produce thrust at the exhaust port. These differences in operating conditions between gas turbines and internal combustion engines result in different operating environments and stresses.

[0135] In one embodiment of the present invention, the engine operates at a speed of 500 rpm to 3000 rpm, or 800 rpm to 2800 rpm, or further 1000 rpm to 2600 rpm, or less than 3,000 rpm, or less than 2,500 rpm, or less than 2,000 rpm. In addition, the engine may operate at an average effective pressure of 10 bar to 15 bar, or 10 to 20 bar, or 10 to 30 bar, or 12 bar to 24 bar.

[0136] In one embodiment, the present disclosure relates to a lubricant composition disclosed herein, which can reduce low-speed premature ignition events in a spark-ignition direct-injection internal combustion engine operating under a load having a net mean effective pressure (BMEP) of 10 bar or more at a speed of 3,000 rpm or less.

[0137] In another embodiment, the disclosure relates to a method for reducing low-speed premature ignition by supplying a lubricant composition disclosed herein to a spark-ignition direct-injection internal combustion engine. The method further comprises supplying 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 more.

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

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

[0140] In different embodiments, the lubricating composition may have the compositions listed in the following table. [Table 4] [Examples]

[0141] The present disclosure will be further illustrated by the following examples illustrating particularly advantageous embodiments. Examples are provided to illustrate the present invention, but are not intended to limit the invention.

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

[0143] Preparation Example A (EXA) (Part i) 1250 g of 4-methyl-2-pentanol is placed in a 3 L reaction vessel equipped with a high-shear mixer and a screw-feed powder addition funnel, and heated to 60°C. 752.5 g of solid phosphorus pentoxide is added to the addition funnel and added over 1 hour and 45 minutes while the high-shear mixer is operated at 6000 rpm. The reaction mixture is maintained at 60°C for a further 1.5 hours, after which the mixture is vacuum-stripped for 30 minutes to obtain the intermediate alkyl phosphoric acid (1958.5 g).

[0144] (Part ii) The alkyl phosphate (12030 g) obtained from Part (i) above (combined with the previous similar batch) is placed in 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 about half of the amine has been added, the diluent oil (350 g) is added. The resulting orange liquid product is used without further purification (2352.3 g).

[0145] Preparation Example B (EXB) (Part i) Add 2-hydroxyethyl acrylate (97% purity, 797 g, 6.65 mol) warmed to 40°C to a 5 L four-necked round-bottom flask equipped with a nitrogen subsurface inlet tube, thermocouple, mechanical glass rod stirrer, and a Friedrich cold water condenser connected to a 25% sodium hydroxide trap and a bleach trap. Add O,O'-di(4-methyl-2-pentyl)dithiophosphate (2500 g, 6.86 mol, based on the total acid value determined by analysis) dropwise over 2 hours (or 1 to 2.5 hours) at a temperature of 55°C to 65°C using a pressure-equalizing funnel. After the addition is complete, set the reaction temperature to 65°C (or 65°C to 70°C) and stir the reactants at this temperature for 7 hours (or 3 to 5 hours or until the hydroxyethyl acrylate is consumed). Cool the resulting intermediate to ambient temperature to obtain a liquid (3297 g) and store under an inert atmosphere.

[0146] (Part II) Add the intermediate from Part I (2872 g, 8.00 mol, based on the amount of available OH groups determined by analysis) to a 5 L four-necked round-bottom flask equipped in the same manner. Add anhydrous sodium methoxide (1 g, 18.5 mmol) all at once and stir the reaction for a further 5 minutes. Add dimethyl phosphite (449 g, 4.08 mol) all at once and slowly heat the reaction to 95°C while blowing nitrogen through a surface tube at approximately 28 L / hour (approximately 1.0 sfch). Hold the reaction mixture at 95°C (or 90-100°C) for 8 hours, collect the distillate and remove it 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 to 90°C, to the flask and stir for a further 15 minutes. Using an additional 55 g of filter aid, the filter cake is packed into a Buchner funnel under vacuum. The contents of a 5 L flask are then filtered through this cake to obtain the product as a clear, pale yellowish-brown liquid (2802 g, 9.5 wt% phosphorus).

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

[0148] Preparation Example E (EXE) In a 5 L round-bottom flask equipped with a reflux condenser, mechanical stirrer, and nitrogen inlet, 1700 g of mixed amyl / isobutyldialkyldithiophosphate (C4 / C5 alkyl group weight ratio 60:40) was added and heated to 62°C. Methyl acrylate (196.4 g) was slowly added while maintaining the reaction temperature below 80°C. After the addition of acrylate was complete, the reaction mixture was heated to 98°C and held at that temperature for 4 hours. After the mixture was cooled to 40°C, propylene oxide (43.7 g) was added via a subsurface tube. The reaction mixture was 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 compound of the present invention, a metal detergent, an ashless dispersant, an antioxidant, and other conventional additives such as polymer viscosity index improvers, friction modifiers, corrosion inhibitors, pour point depressants, and foam inhibitors (Table 1). [Table 2] 1. Unless otherwise specified, all processing speeds are oil-free. 2. Polyisobuenyl succinimide prepared from high-vinylidene PIB (2000Mn PIB, TBN 26 mg KOH / g) 3. Boronated polyisobutenyl succinimide (2000mn PIB, TBN 26mg KOH / g, 0.8 wt% boron) 4. Overbasic calcium alkylbenzene sulfonate (TBN 520 mg KOH / g, 20% by weight Ca) 5. Overbasic calcium alkylbenzene sulfonate (TBN 690 mg KOH / g, 16% Mg by weight) 6. Other additives include friction modifiers, corrosion inhibitors, pour point depressants, and foam inhibitors.

[0150] The lubrication examples were evaluated for their ability to reduce or eliminate premature ignition events in low-speed engines operating at high net mean effective pressures (BMEP), as well as for general lubrication performance such as wear reduction, oxidation prevention, and cleanliness / deposit control (Table 3).

[0151] Low-speed premature ignition (LSPI) was evaluated in a Ford 2.0L EcoBoost turbocharged gasoline direct injection (GDI) engine. The Ford EcoBoost engine was operated at 1750 rpm and 17.0 bar BMEP. The engine was run for a total of 175,000 combustion cycles under these conditions, and LSPI events were counted. The two stages were repeated four times, and the number of premature ignition events was recorded as the average. Table 2 below shows the average LSPI events over the four runs. An LSPI event was determined by monitoring the peak cylinder pressure (PP) and the mass fraction combustion (MFB) of the fuel charge in the cylinder. If both criteria were met, an LSPI event was determined to have occurred. 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 delayed, i.e., burned more than 5.5 degrees after top dead center (ATDC).

[0152] Wear resistance is evaluated using a high-frequency reciprocating rig (HFRR). The HFRR is available from PCS Instruments. The test conditions for evaluation were a steel ball on a hardened steel disk, a 200g load, a duration of 60 minutes, and a frequency of 20 Hz, with the temperature kept constant at 120°C.

[0153] Oxidation resistance and cleanliness are evaluated using 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] Since some of the materials described above may interact in the final formulation, it is known that the components of the final formulation may differ from those initially added. Products formed herein, including those formed when using the lubricant compositions of the present invention in their 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 lubricant compositions prepared by mixing the above components.

[0155] Unless otherwise stated herein, references to the processing rate or amount of components present in the lubricating compositions disclosed herein are based on an oil-free standard, i.e., the amount of active substance.

[0156] As used herein, the terms “hydrocarbyl substituent” or “hydrocarbyl group” are used in their ordinary sense as is well known to those skilled in the art. Specifically, they refer to groups having carbon atoms directly bonded to the rest of the molecule and primarily possessing hydrocarbon properties, 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, as well as aromatic, aliphatic, and alicyclic substituted aromatic substituents, and cyclic substituents where the ring is completed via another part of the molecule (e.g., two substituents together form a ring); substituted hydrocarbon substituents, i.e., substituents in the context of the present invention that contain non-hydrocarbon groups that do not primarily alter the hydrocarbon properties of the substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy); and heterosubstituted substituents, i.e., substituents in the context of the present invention that primarily possess hydrocarbon properties but otherwise contain non-carbon groups in a ring or chain composed of carbon atoms, and include substituents as pyridyl, furyl, thienyl, and imidazolyl. Examples of heteroatoms include sulfur, oxygen, and nitrogen. Generally, there are two or fewer non-hydrocarbon substituents for every 10 carbon atoms in the hydrocarbyl group, or alternatively, there may be no non-hydrocarbon substituents in the hydrocarbyl group.

[0157] This disclosure is not limited to the specific embodiments described in this application, but is intended as an example of various embodiments. 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 invention. In addition to those enumerated herein, functionally equivalent methods and components within the scope of this 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. This disclosure should be limited only by the terminology of such claims, together with the entire scope of equivalents to which the appended claims are granted. This disclosure is not limited to specific methods, reagents, compounds, or compositions, which are, of course, subject to change. It should also be understood that the terminology used herein is intended solely to describe specific embodiments and is not intended to limit them.

[0158] Where used herein, the singular forms “a,” “an,” and “the” include plural references unless the context explicitly indicates otherwise. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art. Nothing in this disclosure should be construed as an acknowledgment that the embodiments described herein are not entitled to precede such disclosure by prior art. Where used herein, the term “including” means “including, but not limited to.”

[0159] Various compositions, methods, and devices are described in relation to various components or steps “including” (to be interpreted as “including, but not limited to”), but compositions, methods, and devices may further “essentially consist of” or “consist of” various components and steps, and such terminology should be interpreted as essentially defining a closed set of elements.

[0160] With regard to the use of substantially any plural and / or singular terms herein, those skilled in the art can convert from plural to singular and / or singular to plural as appropriate to the context and / or use. Various singular / plural conversions may be explicitly described herein for clarity.

[0161] In general, it will be understood by those skilled in the art that the terms used herein, in particular in the appended claims (e.g., the body of the appended claims), are generally intended as “open” terms (for example, the term “includes” should be interpreted as “includes but not limited to,” the term “has” should be interpreted as “has at least,” and the term “includes” should be interpreted as “includes but not limited to,” etc.). If a particular number of claims to be introduced is intended, such intention will be explicitly stated in the claims, and if such statement is not present, such intention will not be present, as will be understood by those skilled in the art. For example, for the sake of understanding, the following appended claims may include the use of the introductory phrases “at least one” and “one or more” to introduce the claims. However, the use of such phrases should not be interpreted as implying that the introduction of a claim description by the indefinite article "a" or "an" limits any particular claim containing such introduced claim description to only one embodiment containing such description, even if the same claim contains the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an" (for example, "a" and / or "an" should be interpreted as meaning "at least one" or "one or more"). The same applies to the use of definite articles used to introduce claim descriptions. In addition, even if a particular number of claims being introduced is explicitly stated, a person skilled in the art will recognize that such a statement should be interpreted as meaning at least the number stated (for example, the explicit statement "two descriptions" without other modifying phrases means at least two descriptions or two or more descriptions). Furthermore, where a clause similar to “at least one of A, B, and C, etc.” is used, such a configuration is generally intended in a sense that a person skilled in the art would understand the clause (for example, “a system having at least one of A, B, and C” includes, but is not limited to, a system having only A, only B, only C, both A and B, both A and C, both B and C, and / or a system having both A, B, and C).Where a clause similar to “at least one of A, B, or C” is used, such a construction is generally intended in a sense that a person skilled in the art would understand the clause to be (for example, “a system having at least one of A, B, or C” includes, but is not limited to, A only, B only, C only, A and B together, A and C together, B and C together, and / or a system having A, B, and C together). A person skilled in the art will further understand that substantially any disjunctive word and / or phrase presenting two or more alternative terms should be understood, whether in the specification, claims, or drawings, as intended to include the possibility of including one of the terms, either of the terms, or both of the terms. For example, the phrase “A or B” will be understood to include the possibility of “A” or “B” or “A and B”.

[0162] In addition, if any feature or aspect of the present disclosure can be described in relation to the Markush group, a person skilled in the art will recognize that the present disclosure also describes any individual element or subgroup of elements of the Markush group.

[0163] For all purposes, including providing written explanations, as will be understood by those skilled in the art, all scopes disclosed herein also encompass all possible sub-scopes and combinations thereof. Any enumerated scope can be readily recognized as fully explaining and enabling that the same scope can be decomposed into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each scope discussed herein can readily be decomposed into lower thirds, middle thirds, upper thirds, etc. As will be understood by those skilled in the art, all words such as “maximum,” “at least,” etc., refer to a scope that includes the number described above and can subsequently be decomposed into sub-scopes. Finally, as will be understood by those skilled in the art, a scope includes each individual element. Thus, for example, a group having 1–3% by weight refers to a group having 1, 2, or 3% by weight. Similarly, a group having 1–5% by weight refers to a group having 1, 2, 3, 4, or 5% by weight, etc., and includes all points in between.

[0164] Furthermore, if a range is provided for processing speed, such a range is intended to include the processing speed for individual components and / or mixtures of components. For example, a range of 1–3% by weight is intended to mean that a given component may exist in a range of 1–3% by weight, or that a mixture of similar components may exist in a range of 1–3% by weight.

[0165] As used herein, the term “approximately” means that the value of a given quantity is within ±20% of the stated value. In other embodiments, the value is within ±15% of the indicated value. In other embodiments, the value is within ±10% of the indicated value. In other embodiments, the value is within ±5% of the indicated value. In other embodiments, the value is within ±2.5% of the indicated value. In other embodiments, the value is within ±1% of the stated value.

[0166] Unless otherwise specified, "weight percent" as used herein refers to a weight percent based on the total weight of this oil-free base lubricating composition. The present invention provides, for example, the following items: (Item 1) A lubricant composition, Lubricating viscosity base oil, Abrasion-resistant agent containing ashless phosphorus, Alkaline earth metal cleaner, Ash-free antioxidant, It contains an ashless dispersant, A lubricant composition that is substantially zinc-free. (Item 2) The lubricant composition according to claim 1, wherein the oil having the aforementioned lubricating viscosity constitutes 80 to 95% by weight of the lubricant composition. (Item 3) The lubricant composition according to claim 2, wherein the oil having the aforementioned lubricating viscosity constitutes 80 to 90% by weight of the lubricant composition. (Item 4) The lubricant composition according to any one of claims 1 to 3, wherein the aforementioned ashless phosphorus-containing wear-resistant agent is an organophosphorus wear-resistant agent. (Item 5) The lubricant composition according to any one of claims 1 to 4, wherein the abrasion-resistant agent containing ashless phosphorus is selected from phosphite, (thio)phosphate, (thio)phosphate amine salt, and combinations thereof. (Item 6) The lubricant composition according to claim 5, wherein the (thio)phosphate amine salt is an alkylphosphate amine salt. (Item 7) The lubricant composition according to claim 6, wherein at least 30 mol% of the phosphorus atoms in the alkyl phosphate amine salt are alkyl pyrophosphate structures. (Item 8) The amine alkylpyrophosphate salt is of formula (I) or (II):

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Claims

1. A lubricant composition for reducing low-speed premature ignition in a spark-ignition direct-injection internal combustion engine, Lubricating viscosity base oil, A phosphorus-free abrasion-resistant agent, which is an amine alkylpyrophosphate or sulfur-containing phosphite, Alkaline earth metal cleaner, Ash-free antioxidant, It contains an ashless dispersant, Contains less than 50 ppm of zinc, The amine alkylpyrophosphate salt is of formula (I) or (II): 【Chemistry 27】 Includes species represented by In the formula, each R1 is independently a primary alkyl group having 3 to 12 carbon atoms, each R2 is independently a hydrogen group, a hydrocarbyl group, or an ester-containing group, at least one R2 group is a hydrocarbyl group or an ester-containing group, or an -OH group is substituted with an -OR1 group, or one or more -OR1 groups are substituted with an -OH group, or an R1 group is substituted with a phosphorus-containing group. The aforementioned sulfur-containing phosphite is 【Chemistry 28】 Represented by, In the formula, R1 and R2 are each independently a hydrocarbyl group having 3 to 12 carbon atoms or 6 to 8 carbon atoms, or 【Chemistry 29】 It is a base represented by, Alternatively, a lubricant composition in which R1 and R2, together with adjacent O and P atoms, form a ring containing 2 to 6 carbon atoms, R3 is hydrogen or a methyl group, R4 is an alkylene group having 2 to 6 carbon atoms, R5 is hydrogen or a hydrocarbyl group having 1 to 12 carbon atoms, and n is 1.

2. The lubricant composition according to claim 1, wherein the oil having the aforementioned lubricating viscosity constitutes 80 to 95% by weight of the lubricant composition.

3. The lubricant composition according to claim 2, wherein the oil having the aforementioned lubricating viscosity constitutes 80 to 90% by weight of the lubricant composition.

4. Amine alkylpyrrophosphates are of formula (I) or (II): 【Chemistry 1】 Includes species represented by In the formula, each R １ Each R is independently a primary alkyl group with 3 to 12 carbon atoms, ２ Each is independently a hydrogen atom, 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 Substituted with or one or more -OR １ The group is substituted with an -OH group, or R １ The lubricant composition according to claim 1, wherein the group is substituted with a phosphorus-containing group.

5. Amine alkylpyrrophosphates are of formula (I) or (II): 【Chemistry 2】 Includes species represented by In the formula, each R １ is independently a primary alkyl group having 3 to 12 carbon atoms, and each R ２ is independently hydrogen, a hydrocarbyl group or an ester-containing group, and at least one R ２ group is a hydrocarbyl group or an ester-containing group. The lubricant composition according to claim 1 or 4.

6. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in the lubricant composition in an amount of 0.1 to 1.5% by weight.

7. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in the lubricant composition in an amount of 0.3 to 1.2% by weight.

8. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in the lubricant composition in an amount of 0.5 to 1.1% by weight.

9. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in the lubricant composition in an amount of 0.6 to 0.9% by weight.

10. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in an amount that brings 500 to 900 ppm of phosphorus into the lubricant composition.

11. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in an amount that brings 550 to 850 ppm of phosphorus into the lubricant composition.

12. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in an amount that brings 600 to 825 ppm of phosphorus into the lubricant composition.

13. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in an amount that brings 650 to 800 ppm of phosphorus into the lubricant composition.

14. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent is present in an amount that brings 700 to 800 ppm of phosphorus into the lubricant composition.

15. The lubricant composition according to claim 1, wherein the alkaline earth metal cleaner is selected from alkaline earth metal sulfonates, phenates, and salicylates.

16. The lubricant composition according to claim 15, wherein the metal of the alkaline earth metal cleaner is selected from calcium and magnesium.

17. The lubricant composition according to claim 16, wherein the alkaline earth metal cleaner is a calcium sulfonate cleaner.

18. The lubricant composition according to claim 16, wherein the alkaline earth metal cleaner is a magnesium sulfonate cleaner.

19. The lubricant composition according to claim 1, wherein the alkaline earth metal cleaner is present in the lubricant composition in an amount of 0.3 to 2.5% by weight.

20. The lubricant composition according to claim 1, wherein the alkaline earth metal cleaner is present in the lubricant composition in an amount of 0.5 to 2.0% by weight.

21. The lubricant composition according to claim 1, wherein the alkaline earth metal cleaner is present in the lubricant composition in an amount of 0.6 to 1.8% by weight.

22. The lubricant composition according to claim 1, wherein the alkaline earth metal cleaner comprises a mixture of alkaline earth metal cleaners, and the mixture is present in the lubricant composition in an amount of 0.8 to 2.0% by weight.

23. The lubricant composition according to claim 22, wherein the mixture of alkaline earth metal detergents comprises, based on the total weight of the lubricant composition, 0.4 to 0.8% by weight of calcium sulfonate detergent and 0.6 to 1.1% by weight of magnesium sulfonate detergent.

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

25. The lubricant composition according to claim 24, wherein the antioxidant is an alkylated diarylamine.

26. The lubricant composition according to claim 24, wherein the antioxidant is an olefin sulfide.

27. The lubricant composition according to claim 1, wherein the antioxidant is present in the lubricant composition in an amount of 0.1 to 2.1% by weight.

28. The lubricant composition according to claim 1, wherein the antioxidant is present in the lubricant composition in an amount of 0.2 to 1.8% by weight.

29. The lubricant composition according to any one of claims 24 to 28, wherein the antioxidant comprises 0.8 to 1.3% by weight of an alkylated diarylamine and 0.1 to 0.5% by weight of a sulfurized olefin.

30. The lubricating composition according to claim 1, wherein the ashless dispersant is a polyisobutylene succinimide dispersant.

31. The lubricant composition according to claim 30, wherein the polyisobutylene succinimide dispersant is boro-oxidized.

32. The lubricant composition according to claim 1, wherein the ashless dispersant is present in the lubricant composition in an amount of 1 to 6% by weight.

33. The lubricant composition according to claim 1, wherein the ashless dispersant comprises 0.8 to 1.6% by weight of a boron-free polyisobutylene succinimide dispersant and 1.8 to 3.1% by weight of a polyisobutylene borooxide dispersant.

34. The lubricant composition according to claim 33, wherein one or more of the boron-free polyisobutylene succinimide dispersant and the borooxide polyisobutylene succinimide dispersant are produced by a direct alkylation process.

35. The lubricant composition according to claim 1, wherein the ashless phosphorus-containing wear-resistant agent contains sulfur, and the sulfur-to-phosphorus ratio is less than 2:

1.

36. The lubricant composition according to claim 1, wherein the lubricant composition can reduce low-speed premature ignition events in a spark-ignition direct-injection internal combustion engine operated under a load having a net mean effective pressure (BMEP) of 10 bar or more at a speed of 3,000 rpm or less.

37. A method for reducing low-speed premature ignition of an engine, comprising supplying the lubricant composition described in claim 1 to a spark-ignition direct-injection internal combustion engine.

38. The method according to claim 37, wherein the engine is operated at a speed of 3,000 rpm or less under a load having a net mean effective pressure (BMEP) of 10 bar or more.

39. The method according to claim 37 or 38, wherein the engine is supplied with a liquid hydrocarbon fuel, a liquid non-hydrocarbon fuel, or a mixture thereof.

40. Use of the lubricant composition according to claim 1 for reducing low-speed premature ignition in a spark-ignition direct-injection internal combustion engine.

41. The use according to claim 40, wherein the engine is operated at a speed of 3,000 rpm or less under a load having a net mean effective pressure (BMEP) of 10 bar or more.

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