Lubricating oil additive composition and lubricating oil composition

Abstract

To provide an ash-free lubricant additive composition having excellent friction-wear properties and a lubricant composition containing the lubricant additive composition.SOLUTION: A lubricant additive composition contains one or more dicarboxylic acid ester compounds (A) selected from the group consisting of maleic acid ester compounds (A1) having a specific structure and succinic acid ester compounds (A2) having a specific structure. A lubricating oil composition contains the lubricating oil additive composition and a lubricating oil base oil.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a lubricating oil additive composition and a lubricating oil composition containing the lubricating oil additive composition. [Background technology]

[0002] One of the typical lubricating oil additives is a friction modifier, such as a molybdenum-based friction modifier such as molybdenum dithiocarbamate (MoDTC). In recent years, metal-free ashless friction modifiers have also been studied in consideration of adverse environmental effects, etc. For example, Patent Document 1 proposes a lubricating oil composition containing glycerol monooleate as an ashless friction modifier. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 5,114,603 Summary of the Invention [Problem to be solved by the invention]

[0004] However, glycerol monooleate does not have sufficient friction-reducing properties and anti-wear properties (hereinafter, these are also collectively referred to as "friction and wear properties"). Therefore, there is a demand for the development of an ashless lubricating oil additive composition that has better friction and wear properties.

[0005] An object of the present invention is to provide an ashless lubricating oil additive composition having excellent friction and wear properties, and a lubricating oil composition containing the lubricating oil additive composition. [Means for solving the problem]

[0006] According to the present invention, the following [1] to [3] are provided. [1] A lubricating oil additive composition comprising one or more dicarboxylic acid ester compounds (A) selected from the group consisting of maleic acid ester compounds (A1) represented by the following general formula (I) and succinic acid ester compounds (A2) represented by the following general formula (II): [ka] [In the general formula (I), R 1 and R 2 each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. 1 and R 2 At least one of R is not a hydrogen atom. 3 and R 4 each independently represents an alkylene group having 2 to 4 carbon atoms; and a and b each independently represent an integer of 0 to 6. [ka] [In the general formula (II), R 11 and R 12 each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. 11 and R 12 At least one of R is not a hydrogen atom. 13 and R 14 each independently represents an alkylene group having 2 to 4 carbon atoms; c and d each independently represents an integer of 0 to 6; G represents a substituent; and m is 1 or 2.] [2] A method for using the lubricating oil additive composition according to [1] above as a friction modifier. [3] A lubricating oil composition comprising the lubricating oil additive composition according to [1] above and a lubricating oil base oil. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an ashless lubricating oil additive composition having excellent friction and wear properties, and a lubricating oil composition containing the lubricating oil additive composition. DETAILED DESCRIPTION OF THE INVENTION

[0008] The upper and lower limits of the ranges described herein can be combined in any way. For example, when the ranges are "A to B" and "C to D," the ranges "A to D" and "C to B" are also included in the scope of the present invention. Furthermore, unless otherwise specified, the numerical range "lower limit to upper limit" described in this specification means that the range is equal to or greater than the lower limit and equal to or less than the upper limit. In this specification, the numerical values ​​in the examples are numerical values ​​that can be used as upper or lower limit values.

[0009] [Embodiments of lubricating oil additive composition] The lubricating oil additive composition of this embodiment contains one or more dicarboxylic acid ester compounds (A) selected from the group consisting of maleic acid ester compounds (A1) represented by the following general formula (I) and succinic acid ester compounds (A2) represented by the following general formula (II): [ka] [In the general formula (I), R 1 and R 2 each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. 1 and R 2 At least one of R is not a hydrogen atom. 3 and R 4 each independently represents an alkylene group having 2 to 4 carbon atoms; and a and b each independently represent an integer of 0 to 6. [ka] [In the general formula (II), R 11 and R 12each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. 11 and R 12 At least one of R is not a hydrogen atom. 13 and R 14 each independently represents an alkylene group having 2 to 4 carbon atoms; c and d each independently represents an integer of 0 to 6; G represents a substituent; and m is 1 or 2.]

[0010] The present inventors have conducted extensive research to solve the above problems, and as a result have found that one or more dicarboxylic acid ester compounds (A) selected from the group consisting of maleic acid ester compounds (A1) represented by the above general formula (I) and succinic acid ester compounds (A2) represented by the above general formula (II) have excellent friction and wear properties, and have also found that these compounds can be suitably used as additive compositions for lubricating oils (particularly as friction modifiers). The reason why one or more dicarboxylic acid ester compounds (A) selected from the group consisting of maleic acid ester compounds (A1) represented by the above general formula (I) and succinic acid ester compounds (A2) represented by the above general formula (II) have excellent friction and wear properties is not clear, but it is presumed that this is due to, for example, the formation of a lipid bilayer on the sliding surface.

[0011] In the following description, the "dicarboxylic acid ester compound (A)," the "maleic acid ester compound (A1)," and the "succinic acid ester compound (A2)" may be abbreviated as "compound (A)," "compound (A1)," and "compound (A2)," respectively.

[0012] The maleate-based compound (A1) and the succinate-based compound (A2) will be described in detail below.

[0013] <Maleic acid ester compound (A1)> The maleate compound (A1) is represented by the following general formula (I). [ka]

[0014] The maleate compound (A1) loses its effect when its skeleton is changed to an unsubstituted succinic acid skeleton. Therefore, it is believed that the presence of a maleic acid skeleton (having a C=C double bond that is not present in a succinic acid skeleton) plays an important role in achieving the effect of the present invention.

[0015] In the above general formula (I), R 1 and R 2 each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. 1 and R 2 At least one of the groups is not a hydrogen atom. R 1 and R 2 If both of these are hydrogen atoms, the solubility in the lubricating base oil cannot be ensured, and the effects of the present invention cannot be achieved. Furthermore, when the number of carbon atoms in the alkyl group and alkenyl group is less than 8 or more than 24, the solubility in the lubricating base oil cannot be ensured, and the effects of the present invention cannot be achieved.

[0016] R 1 and R 2 Examples of the alkyl group having 8 to 24 carbon atoms that can be selected as aryl include an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an icosyl group, a heneicosyl group, a docosyl group, a tricosyl group, and a tetracosyl group. These may be straight-chain, branched-chain, or cyclic, but are preferably straight-chain or branched-chain, and more preferably straight-chain. Furthermore, from the viewpoint of improving the effects of the present invention, the alkyl group preferably has 10 to 20 carbon atoms, more preferably 10 to 18 carbon atoms, and even more preferably 10 to 16 carbon atoms.

[0017] R 1and R 2 Examples of alkenyl groups having 8 to 24 carbon atoms that can be selected as include an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, an octadecenyl group, an oleyl group, a nonadecenyl group, an icosenyl group, a henicosenyl group, a docosenyl group, a tricosenyl group, and a tetracosenyl group. These may be straight-chain, branched-chain, or cyclic, but are preferably straight-chain or branched-chain, and more preferably straight-chain. In order to improve the effects of the present invention, the alkenyl group preferably has 10 to 20 carbon atoms, more preferably 10 to 18 carbon atoms, and even more preferably 10 to 16 carbon atoms.

[0018] where R 1 and R 2 The groups that can be selected as R are selected from the viewpoints of improving the effects of the present invention and facilitating the synthesis of the maleic acid ester compound (A1). 1 and R 2 are each independently a linear alkyl group having 8 to 24 carbon atoms or a linear alkenyl group having 8 to 24 carbon atoms, and more preferably a linear alkyl group having 8 to 24 carbon atoms. In this case, the preferred carbon numbers of the linear alkyl group and linear alkenyl group are the same as those described above.

[0019] In the above general formula (I), R 3 and R 4 each independently represents an alkylene group having 2 to 4 carbon atoms, and a and b each independently represent an integer of 0 to 6. When a and b are 2 or more, if the alkylene group has 1 or more than 4 carbon atoms, it becomes difficult to synthesize the maleate ester compound (A1). If a and b are greater than 6, the solubility in the lubricating base oil cannot be ensured, and the effects of the present invention cannot be achieved.

[0020] R 3 and R 4Specific examples of alkylene groups having 2 to 4 carbon atoms that can be selected for include -CH2CH2-, -CH2CH(CH3)-, -CH2CH(CH2CH3)-, and CH2CH(CH3)CH2-, etc. Among these, -CH2CH2- and -CH2CH(CH3)- are preferred, with -CH2CH2- being more preferred.

[0021] a and b are preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, from the viewpoint of ease of synthesis of the maleic acid ester compound (A1) and improvement of the effects of the present invention.

[0022] The maleic acid ester-based compound (A1) may be used alone or in combination of two or more.

[0023] <Method for synthesizing maleic acid ester compound (A1)> The method for synthesizing the maleic acid ester compound (A1) is not particularly limited, but it can be synthesized, for example, by an esterification reaction between maleic acid (or maleic anhydride) and an alcohol. Specifically, the esterification reaction of maleic acid (or maleic anhydride) with alcohol is carried out at atmospheric pressure at a reaction temperature of 50°C to 200°C. The reaction temperature is preferably 100°C to 150°C. Examples of solvents that can be used for the esterification include aliphatic hydrocarbon solvents such as dimethyl sulfoxide, hexane, heptane, and cyclohexane, and aromatic hydrocarbon solvents such as toluene, xylene, cumene, and dichlorobenzene. The esterification reaction may also be carried out in the presence of a solvent that forms an azeotrope with water, such as hexane, heptane, cyclohexane, toluene, xylene, cumene, and dichlorobenzene. The catalyst for the esterification reaction is an acid, which can be selected from inorganic acids such as sulfuric acid, sulfonic acid, phosphoric acid, p-toluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, and dodecylsulfonic acid derivatives. The reaction can be carried out in a homogeneous single-phase medium. Alternatively, the catalyst can be supported on a solid polymer or an acidic ion-exchange resin. In this case, the reaction can be carried out in a heterogeneous two-phase medium. As the catalyst, p-toluenesulfonic acid is preferably used.

[0024] <Succinate ester compounds (A2)> The succinate compound (A2) is represented by the following general formula (II). [ka]

[0025] As described above, when the skeleton of the maleate ester compound (A1) is changed to an unsubstituted succinic acid skeleton, the effects of the present invention are no longer exhibited. However, even if the skeleton is a succinic acid skeleton, the effects of the present invention can be exhibited by having the substituent G.

[0026] In the above general formula (II), R 11 and R 12 each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. 11 and R 12 At least one of the groups is not a hydrogen atom. R 11 and R 12 If both of these are hydrogen atoms, the solubility in the lubricating base oil cannot be ensured, and the effects of the present invention cannot be achieved. Furthermore, when the number of carbon atoms in the alkyl group and alkenyl group is less than 8 or more than 24, the solubility in the lubricating base oil cannot be ensured, and the effects of the present invention cannot be achieved.

[0027] R 11 and R 12 The alkyl group having 8 to 24 carbon atoms that can be selected as R 1 and R 2 Examples include the following. The alkyl group may be linear, branched, or cyclic, but is preferably linear or branched, and more preferably linear. Furthermore, from the viewpoint of improving the effects of the present invention, the alkyl group preferably has 10 to 20 carbon atoms, more preferably 10 to 18 carbon atoms, and even more preferably 10 to 16 carbon atoms.

[0028] R 11 and R 12 The alkenyl group having 8 to 24 carbon atoms that can be selected as R 1 and R 2 Examples include the following. The alkenyl group may be linear, branched, or cyclic, but is preferably linear or branched, and more preferably linear. In order to improve the effects of the present invention, the alkenyl group preferably has 10 to 20 carbon atoms, more preferably 10 to 18 carbon atoms, and even more preferably 10 to 16 carbon atoms.

[0029] where R 11 and R 12 The groups that can be selected as R are selected from the viewpoints of improving the effects of the present invention and facilitating the synthesis of the succinate ester compound (A2). 11 and R 12 are each independently a linear alkyl group having 8 to 24 carbon atoms or a linear alkenyl group having 8 to 24 carbon atoms, and more preferably a linear alkyl group having 8 to 24 carbon atoms. In this case, the preferred carbon numbers of the linear alkyl group and linear alkenyl group are the same as those described above.

[0030] In the above general formula (II), R 13 and R 14 each independently represents an alkylene group having 2 to 4 carbon atoms, and c and d each independently represents an integer of 0 to 6. When c and d are 2 or more, if the alkylene group has 1 or more than 4 carbon atoms, it becomes difficult to synthesize the succinate ester compound (A2). If c and d are greater than 6, the solubility in the lubricating base oil cannot be ensured, and the effects of the present invention cannot be achieved.

[0031] R 13 and R 14 The alkylene group having 2 to 4 carbon atoms that can be selected as R 3 and R 4Among these, -CH2CH2- and -CH2CH(CH3)- are preferred, and -CH2CH2- is more preferred.

[0032] c and d are preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, from the viewpoint of ease of synthesis of the succinate ester compound (A2) and improvement of the effects of the present invention.

[0033] In the above general formula (II), G represents a substituent, and m is 1 or 2. m is preferably 1 from the viewpoint of ease of synthesis of the succinate ester compound (A2) and from the viewpoint of improving the effects of the present invention.

[0034] Here, from the viewpoint of improving the effects of the present invention, G is preferably a monovalent group containing one or more heteroatoms selected from the group consisting of sulfur atoms, oxygen atoms, nitrogen atoms, and phosphorus atoms. Specific examples of such groups include the groups exemplified below. In the following groups, each R is independently a hydrogen atom or a hydrocarbon group (preferably a hydrogen atom or a chain alkyl group having 1 to 8 carbon atoms), and each n is independently an integer of 0 to 20 (preferably 0 to 10, more preferably 0 to 8). -OR -O-(CH2) n -CH3 -O-(CH2) n -NH2 -O-(CH2) n -C(=O)-OR -O-(CH2) n -SO3R -OC(=O)-R -OC(=O)-NH-R -OC(=O)-NR-R -OC(=O)-NH-CH(R)-C(=O)-OR -OC(=O)-NH-(CH2) n -SO3R -OC(=O)-NH-(CH2) n -C(=O)-OR -O-C(=O)-OR -O-C(=O)-SR -O-SO2-OR -O-PO2-OR -(OCH2CH2) n -R -(OCH2CH2CH2) n -R -C(=O)-OR -C(=O)-NH-R -C(=O)-NR-R -SO3R -SO2-R -C(=O)-NH-CH(R)-C(=O)-OR -C(=O)-NH-(CH2) n -SO3R -NR2 -NH-R -NH-(CH2) n -NH2 -NH-CH(R)-C(=O)-OR -NH-(CH2) n -SO3R -NH-(CH2) n -SO3R -NH-C(=O)-OR -NH-C(=O)-NH2、 -NH-C(=O)-NH-CH(R)-C(=O)-OR -NH-C(=O)-NH-(CH2) n -SO3R -NH-C(=O)-NH-(CH2) n -C(=O)-OR -O-C(=O)-(CH2) n -NH2 -SR -S-(CH2) n -C(=O)-OR -S-(CH2) n -CH(NH2)-C(=O)-OR -S-S-(CH2) n -CH(NH2)-C(=O)-OR -PO3R -S-P(=S)-(OR)2 -SP(=O)-(OR)2 -OP(=O)-(OR)2 -OP(=S)-(OR)2

[0035] Furthermore, from the viewpoint of improving the effects of the present invention, G is more preferably a group selected from the groups represented by the following general formulas (III) and (IV) among monovalent groups containing one or more heteroatoms selected from the group consisting of sulfur atoms, oxygen atoms, nitrogen atoms, and phosphorus atoms. [ka] [ka]

[0036] In the above general formula (III), X 1 is an oxygen atom, a nitrogen atom, a sulfur atom, or a methylene group. Here, from the viewpoint of improving the effect of the present invention, X 1 is preferably an oxygen atom or a sulfur atom, more preferably a sulfur atom.

[0037] In the above general formula (III), n is an integer of 0-6. Here, n is preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, from the viewpoint of improving the effects of the present invention.

[0038] In the above general formula (III), R 21 is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Here, from the viewpoint of improving the effect of the present invention, R 21 is preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and even more preferably a hydrogen atom.

[0039] In the above general formula (IV), X 2 is an oxygen atom, a nitrogen atom, a sulfur atom, or a methylene group. Here, from the viewpoint of improving the effect of the present invention, X 2 is preferably an oxygen atom or a sulfur atom, more preferably a sulfur atom.

[0040] In the above general formula (IV), R 31 and R 32 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Here, from the viewpoint of improving the effect of the present invention, R 31 and R 32 are each independently preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, and even more preferably an alkyl group having 1 to 2 carbon atoms.

[0041] The succinate ester-based compounds (A2) may be used singly or in combination of two or more.

[0042] <Method for synthesizing succinic acid ester compound (A2)> The method for synthesizing the succinate compound (A2) is not particularly limited, but for example, it can be synthesized by adding a desired substituent G to the maleate compound (A1). Examples of methods for adding a substituent G to a maleate compound (A1) include a Michael addition reaction of a compound capable of forming the substituent G (e.g., mercaptoacetic acid or O,O-diethyldithiophosphate) in the presence of a basic catalyst. This produces a succinate compound (A2). The reaction temperature is preferably −70°C to 100°C. Solvents that can be used in the addition reaction include aliphatic hydrocarbon solvents such as dimethyl sulfoxide, hexane, heptane, and cyclohexane, and aromatic hydrocarbon solvents such as toluene, xylene, cumene, and dichlorobenzene. The basic catalyst can be selected from triethylamine, diisopropylmethylamine, alumina, triethylborane, and 9-BBN (9-borabicyclo[3.3.1]nonane). Triethylamine is preferred.

[0043] <Preferred Embodiments of Dicarboxylic Acid Ester Compound (A)> From the viewpoint of improving the effects of the present invention, the dicarboxylic acid ester compound (A) is preferably at least one selected from the group consisting of maleic acid ester compounds (A1) and succinic acid ester compounds (A2) in which G is a group represented by the above general formula (III). Among these, from the viewpoint of further improving the abrasion resistance, it is preferable to contain a maleate ester-based compound (A1), and from the viewpoint of reducing the coefficient of friction under high loads (particularly 150 N or more), it is preferable to contain a succinate ester-based compound (A2) in which G is a group represented by the above general formula (III).

[0044] <Content of dicarboxylic acid ester compound (A) in lubricating oil additive composition> In order to more easily achieve the effects of the present invention when added to a lubricating base oil, the lubricating oil additive composition of this embodiment contains the dicarboxylic acid ester compound (A) in an amount of preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total amount of the lubricating oil additive composition. In addition, taking into account the purity of the maleic acid ester compound (A1) and the succinic acid ester compound (A2), the content of the dicarboxylic acid ester compound (A) is usually less than 99% by mass, based on the total amount of the lubricating oil additive composition. The lubricating oil additive composition of this embodiment may be diluted with a diluting solvent from the viewpoint of solubility in the lubricating base oil and ease of handling. The content of the dicarboxylic acid ester compound (A) in the lubricating oil additive composition means the content based on the total amount of the active ingredients in the lubricating oil additive composition excluding the diluting solvent.

[0045] <Uses of lubricating oil additive composition> The lubricating oil additive composition of this embodiment has excellent friction and wear properties and is therefore useful as a friction modifier. Therefore, in this embodiment, there is provided a method for using the lubricating oil additive composition, in which the lubricating oil additive composition is used as a friction modifier.

[0046] [Lubricating oil composition] The lubricating oil composition of this embodiment contains the lubricating oil additive composition and a lubricating base oil. The content of the lubricating oil additive composition is adjusted to preferably 0.05 mass % to 10 mass %, more preferably 0.10 mass % to 5.0 mass %, and even more preferably 0.30 mass % to 2.0 mass %, based on the total amount of the lubricating oil composition, from the viewpoint of ensuring that the additive effect of the lubricating oil additive composition is satisfactorily exhibited.

[0047] <Lubricant base oil> The lubricating base oil may be any base oil commonly used in lubricating oil compositions without any particular limitations, and specifically may be one or more selected from the group consisting of mineral oils and synthetic oils. The kinematic viscosity of the lubricating base oil at 100°C is 1.0 mm 2 / s~50mm 2 / s, and preferably in the range of 1.5 mm 2 / s~30mm 2 / s, and more preferably in the range of 2.0 mm 2 / s~20mm 2 When the kinematic viscosity at 100°C of the lubricating base oil is in the above range, evaporation loss of the lubricating oil composition can be easily reduced, and power loss due to viscous resistance of the lubricating oil composition can be suppressed, making it easier to obtain fuel economy improvement effects, etc. The viscosity index of the lubricating base oil is preferably at least 80, more preferably at least 90, and even more preferably at least 100. When the viscosity index of the lubricating base oil is within the above range, the viscosity characteristics of the lubricating oil composition tend to be good. The kinematic viscosity and viscosity index of the lubricating base oil are values ​​measured or calculated in accordance with JIS K2283:2000.

[0048] Specific examples of lubricating base oils are listed below. Examples of mineral oils include distillate oils obtained by atmospheric and / or vacuum distillation of paraffin-based crude oils, intermediate-based crude oils, or naphthene-based crude oils; refined oils obtained by refining the distillate oils according to conventional methods; etc. Refining methods for obtaining refined oils include, for example, solvent dewaxing, hydroisomerization, hydrofinishing, clay treatment, etc. Examples of synthetic oils include hydrocarbon oils, aromatic oils, ester oils, ether oils, etc. Furthermore, as synthetic oils, GTL (Gas to Liquids) obtained by isomerizing wax (GTL wax, Gas to Liquids Wax) produced from natural gas by the Fischer-Tropsch process or the like may be used.

[0049] <Other additives> The lubricating oil composition of this embodiment may contain other additives such as antioxidants, oiliness agents, detergent-dispersants, viscosity index improvers, rust inhibitors, metal deactivators, and antifoaming agents, to the extent that the effects of the lubricating oil additive composition are not impaired. These may be used alone or in combination of two or more. In addition, in this embodiment, an additive package for a lubricating oil composition is also provided, which contains, together with the lubricating oil additive composition, one or more additives selected from antioxidants, oiliness agents, detergents and dispersants, viscosity index improvers, rust inhibitors, metal deactivators, antifoaming agents, etc. as additives other than the lubricating oil additive composition.

[0050] (antioxidant) As the antioxidant, amine-based antioxidants, phenol-based antioxidants, etc., which are used in conventional lubricating oil compositions, can be used. These antioxidants may be used alone or in combination of two or more. Examples of the amine antioxidant include monoalkyldiphenylamine compounds such as monooctyldiphenylamine and monononyldiphenylamine; dialkyldiphenylamine compounds such as 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, and 4,4'-dinonyldiphenylamine; polyalkyldiphenylamine compounds such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, and tetranonyldiphenylamine; and naphthylamine compounds such as α-naphthylamine, phenyl-α-naphthylamine, butylphenyl-α-naphthylamine, pentylphenyl-α-naphthylamine, hexylphenyl-α-naphthylamine, heptylphenyl-α-naphthylamine, octylphenyl-α-naphthylamine, and nonylphenyl-α-naphthylamine. Examples of phenolic antioxidants include monophenolic compounds such as 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butyl-4-ethylphenol; and bisphenolic compounds such as 4,4'-methylenebis(2,6-di-tert-butylphenol) and 2,2'-methylenebis(4-ethyl-6-tert-butylphenol). The antioxidant content may be the minimum amount necessary to maintain the oxidation stability of the lubricating oil composition, and specifically, for example, is preferably 0.01 to 1 mass % based on the total amount of the lubricating oil composition.

[0051] (oil-based agent) Examples of oily agents include fatty alcohols; fatty acid compounds such as fatty acids and fatty acid metal salts; ester compounds such as polyol esters, sorbitan esters, and glycerides; and amine compounds such as fatty amines. In terms of the effect of addition, the content of the oiliness agent is usually 0.1 to 20 mass %, preferably 0.5 to 10 mass %, based on the total amount of the lubricating oil composition.

[0052] (detergent dispersant) Detergent-dispersants include metal sulfonates, metal salicylates, metal phenates, and succinimides. In terms of the effect of addition, the content of the detergent-dispersant is usually 0.01 to 10 mass %, preferably 0.1 to 5 mass %, based on the total amount of the lubricating oil composition.

[0053] (viscosity index improver) Examples of viscosity index improvers include polymethacrylate, disperse polymethacrylate, olefin copolymers (e.g., ethylene-propylene copolymers), disperse olefin copolymers, and styrene copolymers (e.g., styrene-diene hydrogenated copolymers). The content of the viscosity index improver is preferably 0.3 to 5 mass % based on the total amount of the lubricating oil composition.

[0054] (rust inhibitor) Examples of the rust inhibitor include metal sulfonates, succinic acid esters, and alkanolamines such as alkylamines and monoisopropanolamine. In terms of the effect of addition, the content of the rust inhibitor is usually 0.01 to 5 mass %, and preferably 0.03 to 3 mass %, based on the total amount of the lubricating oil composition.

[0055] (metal deactivator) Examples of the metal deactivator include benzotriazole and thiadiazole. In terms of the effect of addition, the preferred content of the metal deactivator is usually 0.01 to 5 mass %, and preferably 0.01 to 1 mass %, based on the total amount of the lubricating oil composition.

[0056] (Antifoaming agent) Examples of the antifoaming agent include methylsilicone oil, fluorosilicone oil, and polyacrylate. In view of the effect of addition, the content of the antifoaming agent is usually 0.0005 to 0.01 mass % based on the total amount of the lubricating oil composition.

[0057] [Physical properties of lubricating oil composition] <Kinematic viscosity, viscosity index> The lubricating oil composition of this embodiment preferably has a kinematic viscosity at 100°C of 1.0 mm 2 / s~50mm 2 / s, more preferably 1.5 mm 2 / s~30mm 2 / s, more preferably 2.0 mm 2 / s~20mm 2 / s. The viscosity index of the lubricating oil composition of this embodiment is preferably 90 or greater, more preferably 100 or greater, and even more preferably 110 or greater. The kinematic viscosity and viscosity index of the lubricating oil composition are values ​​measured or calculated in accordance with JIS K2283:2000.

[0058] <Coefficient of friction> The lubricating oil composition of this embodiment preferably has a friction coefficient in the following range in the friction and wear test described in the Examples below. That is, when the load is 50 N, the coefficient of friction is preferably 0.075 or less, more preferably 0.070 or less, even more preferably 0.065 or less, and even more preferably 0.60 or less. When the load is 100 N, the coefficient of friction is preferably 0.080 or less, more preferably 0.075 or less, even more preferably 0.070 or less, and even more preferably 0.65 or less. When the load is 150 N, the coefficient of friction is preferably 0.080 or less, more preferably 0.075 or less, even more preferably 0.070 or less, and still more preferably 0.64 or less. When the load is 200 N, the coefficient of friction is preferably 0.080 or less, more preferably 0.075 or less, even more preferably 0.070 or less, still more preferably 0.065 or less, and even more preferably 0.063 or less. The average value of the friction coefficient when the load is 50N to 200N is preferably 0.080 or less, more preferably 0.075 or less, even more preferably 0.070 or less, and even more preferably 0.065 or less. The lubricating oil composition of this embodiment contains the lubricating oil additive composition of this embodiment, and therefore has a low coefficient of friction, and is particularly effective in reducing the coefficient of friction even under a high load of 150 N or more.

[0059] <Wear resistance> The lubricating oil composition of this embodiment has a wear scar diameter in the friction and wear test described in the Examples below, of preferably 440 μm or less, more preferably 430 μm or less, even more preferably 425 μm or less, still more preferably 420 μm or less, even more preferably 415 μm or less, and even more preferably 410 μm or less.

[0060] [Method of manufacturing lubricating oil composition] The method for producing the lubricating oil composition of this embodiment is not particularly limited. For example, the method for producing the lubricating oil composition of this embodiment includes the step of mixing the lubricating oil additive composition with a lubricating base oil. The production method may further include a step of blending the above-mentioned other additives, if necessary. The method for mixing each component is not particularly limited, but for example, a method of blending each component with a lubricating base oil can be mentioned. Also, each component may be blended after adding a diluent oil or the like to form a solution (dispersion). After blending each component, it is preferable to stir and disperse it uniformly by a known method. The preferred embodiments of the lubricating oil additive composition and the lubricating base oil are as described above. The amount of the lubricating oil additive composition to be blended is preferably an amount corresponding to the above-mentioned preferred content of the lubricating oil additive composition.

[0061] [Uses of lubricating oil composition] The lubricating oil composition of this embodiment contains the lubricating oil additive composition of this embodiment, and therefore has excellent friction and wear properties. For this reason, the lubricating oil composition of the present embodiment can be suitably used in a variety of applications, including drive system oils such as gear oils (manual transmission oil, differential oil, etc.), automatic transmission oils (automatic transmission oil, etc.), continuously variable transmission oils (belt CVT oil, toroidal CVT oil, etc.), power steering oil, shock absorber oil, and electric motor oil; oils for internal combustion engines (engines) such as gasoline engines, diesel engines, and gas engines; hydraulic oils; turbine oils; compressor oils; fluid bearing oils; rolling bearing oils; and refrigeration oils, and can be suitably used as a lubricating oil composition that is filled into equipment used in each of these applications and lubricates the components of the equipment.

[0062] [Lubrication method using lubricating oil composition] A preferred lubrication method using the lubricating oil composition of this embodiment is a method in which the lubricating oil composition is filled into equipment used for each of the above-mentioned applications and lubricates the components of each of the equipment.

[0063] [Grease composition] The lubricating oil additive composition of this embodiment can also be used by blending it into a grease composition. That is, in this embodiment, it is also possible to provide a grease composition containing the lubricating oil additive composition, a thickener, and a lubricating base oil.

[0064] [One aspect of the present invention provided] In one aspect of the present invention, the following [1] to [6] are provided. [1] A lubricating oil additive composition comprising one or more dicarboxylic acid ester compounds (A) selected from the group consisting of maleic acid ester compounds (A1) represented by the following general formula (I) and succinic acid ester compounds (A2) represented by the following general formula (II): [ka] [In the general formula (I), R 1 and R 2each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. 1 and R 2 At least one of R is not a hydrogen atom. 3 and R 4 each independently represents an alkylene group having 2 to 4 carbon atoms; and a and b each independently represent an integer of 0 to 6. [ka] [In the general formula (II), R 11 and R 12 each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. 11 and R 12 At least one of R is not a hydrogen atom. 13 and R 14 each independently represents an alkylene group having 2 to 4 carbon atoms; c and d each independently represents an integer of 0 to 6; G represents a substituent; and m is 1 or 2.] [2] The lubricating oil additive composition according to [1] above, wherein in the general formula (II), G is a monovalent group containing one or more heteroatoms selected from the group consisting of sulfur atoms, oxygen atoms, nitrogen atoms, and phosphorus atoms. [3] The lubricating oil additive composition according to [1] or [2] above, wherein in the general formula (II), G is a group selected from groups represented by the following general formulas (III) and (IV): [ka] [In the general formula (III), X 1 is an oxygen atom, a nitrogen atom, a sulfur atom, or a methylene group. n is an integer of 0 to 6. R 21 is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.] [ka] [In the general formula (IV), X 2is an oxygen atom, a nitrogen atom, a sulfur atom, or a methylene group. 31 and R 32 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.] [4] The lubricating oil additive composition according to any one of the above [1] to [3], which is used as a friction modifier. [5] A method for using a lubricating oil additive composition according to any one of the above [1] to [3], which uses the lubricating oil additive composition as a friction modifier. [6] A lubricating oil composition comprising the lubricating oil additive composition according to any one of the above [1] to [4] and a lubricating oil base oil. [Example]

[0065] The present invention will be specifically described with reference to the following examples, although the present invention is not limited to the following examples.

[0066] [Manufacturing Examples 1 to 3] <Production Example 1: Synthesis of maleic acid ester compound (A1)-1> A 1-L flask was equipped with a Dean-Stark tube and a Dimroth condenser and charged with 19.6 g (0.200 mol) of maleic anhydride, 97.0 g (0.400 mol) of 1-hexadecanol, 1.90 g (0.010 mol) of p-toluenesulfonic acid monohydrate, and 200 mL of toluene. The mixture was then heated under reflux and stirred for 6 hours while removing water by azeotropic dehydration. After the reaction was complete, the mixture was cooled on ice, and the precipitated white crystals were collected by filtration and dried to obtain 84.9 g (75.1% yield) of bis(n-hexadecyl) maleate. The structural formula of the maleic acid ester compound (A1)-1 obtained in Production Example 1 is shown below. The maleate compound (A1)-1 is a compound represented by the general formula (I) above, 1 and R 2 is an n-tetradecyl group, and R 3 and R 4 is an ethylene group, and a and b are 1. [ka]

[0067] <Production Example 2: Synthesis of succinic acid ester compound (A2)-1> A four-neck flask equipped with a thermometer and a Dimroth condenser was charged with 22.6 g (0.040 mol) of bis(n-hexadecyl) maleate obtained in Production Example 1, 3.68 g (0.040 mol) of mercaptoacetic acid, and 50 mL of tetrahydrofuran. 4.05 g (0.040 mol) of triethylamine was added, and the mixture was stirred at 50°C for 10 hours. After the reaction, the solvent was distilled off using a rotary evaporator. Hexane was added to the resulting residue, and the precipitated white solid was collected by filtration and dried to obtain 23.18 g (yield 88.0%) of 2-((1,4-bis(n-hexadecyloxy)-1,4-dioxobutan-2-yl)thio)acetic acid. The structural formula of the succinate compound (A2)-1 obtained in Production Example 2 is shown below. The succinate ester compound (A2)-1 is a compound represented by the general formula (II) above, wherein R 11 and R 12 is an n-tetradecyl group, and R 13 and R 14 is an ethylene group, and c and d are 1. G is a group represented by the general formula (III) above, and m is 1. In the general formula (III), X 1 is a sulfur atom, and R 21 is a hydrogen atom and n is 1. [ka]

[0068] <Production Example 3: Synthesis of succinic acid ester compound (A2)-2> 16.95 g (0.03 mol) of bis(n-hexadecyl) maleate obtained in Production Example 1, 5.59 g (0.03 mol) of O,O-diethyldithiophosphate, and 50 mL of tetrahydrofuran were charged, and 3.04 g (0.03 mol) of triethylamine was added. The mixture was heated and stirred at a bath temperature of 60°C for 7 hours. After the reaction, the solvent was distilled off using a rotary evaporator. The resulting residue was purified by flash column chromatography (silica gel: hexane / ethyl acetate = 50:1 to 10:1) to obtain 2.82 g (yield 25.1%) of bis(n-hexadecyl)-2-((diethoxyphosphorothioyl)sulfanyl)succinate. The structural formula of the succinate compound (A2)-2 obtained in Production Example 3 is shown below. The succinate ester compound (A2)-2 is a compound represented by the general formula (II) above, wherein R 11 and R 12 is an n-tetradecyl group, and R 13 and R 14 is an ethylene group, and c and d are 1. G is a group represented by the general formula (IV) above, and m is 1. In the general formula (IV) above, X 2 is a sulfur atom, and R 31 and R 32 is an ethyl group. [ka]

[0069] [Examples 1 to 3 and Comparative Examples 1 to 4] Lubricant base oil (poly-α-olefin (PAO), kinematic viscosity at 100°C = 3.9 mm 2 The following compounds were added to and mixed with a lubricating oil composition (H2O3 / s, viscosity index = 120). The content of the following compounds in the lubricating oil composition was 0.5% by mass. The prepared lubricating oil composition was then subjected to the following evaluations. The 100°C kinematic viscosity and viscosity index of the lubricating base oil were measured or calculated in accordance with JIS K2283:2000.

[0070] The compounds added in Examples 1 to 3 and Comparative Examples 1 to 4 are as follows. Example 1: Maleic acid ester compound (A1)-1 obtained in Production Example 1 Example 2: Succinate ester compound (A2)-1 obtained in Production Example 2 Example 3: Succinate ester compound (A2)-2 obtained in Production Example 3 Comparative Example 1: Oleic Acid [ka] Comparative Example 2: Glycerol monooleate [ka] Comparative Example 3: Molybdenum dialkylthiocarbamate (a binuclear MoDTC in which the carbon numbers of the four alkyl groups are each independently 7 or 13. Abbreviated as "MoDTC" in Table 1.) Comparative Example 4: Bis(n-hexadecyl) succinate [ka]

[0071] <Evaluation 1: Friction and wear test> Using a ball-on-disc type high-speed reciprocating friction tester TE77 (manufactured by Phoenix Tribology), the lubricating oil composition was introduced between the test plate and the test ball, and the test was performed by moving the test ball under the conditions below, and the average friction coefficient at each load was measured. In addition, the wear scar diameters in the vertical and horizontal directions of the test ball after the test were measured, and the average wear scar diameter was calculated using the following formula. Test plate Material: SUJ2, Shape: Length 58mm x Width 38mm x Thickness 3.9mm Test ball: Material: SUJ2, diameter 10mm ·Lubricating conditions: oil bath, oil amount 3mL Load: 50N (300 seconds) → 100N (300 seconds) → 150N (300 seconds) → 200N (300 seconds) ·Temperature: 100℃ ·Amplitude: 10mm Frequency: 10Hz Average wear scar diameter = {(longitudinal wear scar diameter) + (lateral wear scar diameter)} / 2 The lower the friction coefficient, the better the friction-reducing performance of the lubricating oil composition. Furthermore, it can be said that the smaller the wear scar diameter, the more excellent the wear resistance of the lubricating oil composition.

[0072] The results are shown in Table 1.

[0073] [Table 1] The results shown in Table 1 reveal the following: The results shown in Examples 1 to 3 show that the lubricating oil compositions containing the maleate ester compound (A1)-1, the succinate ester compound (A2)-1, or the succinate ester compound (A2)-2 have excellent friction and wear properties. In other words, it can be seen that the maleate ester compound (A1)-1, the succinate ester compound (A2)-1, and the succinate ester compound (A2)-2 are lubricating oil additives with excellent friction and wear properties. In contrast, it is clear that the lubricating oil compositions shown in Comparative Examples 1 to 4 are inferior in friction and wear properties.

[0074] Regarding the lubricating oil compositions of Examples 1 to 3, after blending the maleic acid ester compound (A1)-1, the succinic acid ester compound (A2)-1, or the succinic acid ester compound (A2)-2, the appearance of the lubricating oil compositions was checked and it was confirmed that the lubricating oil compositions were transparent and had good solubility in the lubricating base oil.

Claims

1. A lubricating oil additive composition for use as an ashless friction modifier, comprising one or more dicarboxylic acid ester compounds (A) selected from the group consisting of maleic acid ester compounds (A1) represented by the following general formula (I) and succinic acid ester compounds (A2) represented by the following general formula (II): 【Chemistry 1】 [In the general formula (I), R １ and R ２ each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. １ and R ２ At least one of R is not a hydrogen atom. ３ and R ４ each independently represents an alkylene group having 2 to 4 carbon atoms; and a and b each independently represent an integer of 0 to 6. 【Chemistry 2】 [In the general formula (II), R １１ and R １２ each independently represents a hydrogen atom, an alkyl group having 8 to 24 carbon atoms, or an alkenyl group having 8 to 24 carbon atoms. １１ and R １２ At least one of R is not a hydrogen atom. １３ and R １４ each independently represents an alkylene group having 2 to 4 carbon atoms; c and d each independently represents an integer of 0 to 6; G represents a group selected from groups represented by the following general formulas (III) and (IV); and m is 1 or 2. 【Transformation 3】 [In the general formula (III), X 1 represents an oxygen atom, a nitrogen atom, a sulfur atom, or a methylene group; n represents an integer of 0 to 6; and R 21 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.] 【Chemistry 4】 [In the general formula (IV), X 2 represents an oxygen atom, a nitrogen atom, a sulfur atom, or a methylene group. R 31 and R 32 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.]

2. A method for using the lubricating oil additive composition according to claim 1 as a friction modifier.

3. A lubricating oil composition comprising the lubricating oil additive composition according to claim 1 and a lubricating base oil.

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