Additive composition for lubricating oil and lubricating oil composition

Abstract

To provide an additive composition for lubricating oil that is suitable for use as a load-carrying additive and exhibits superior wear resistance and extreme pressure performance, and a lubricating oil composition comprising the additive composition for lubricating oil.SOLUTION: An additive composition for lubricating oil is obtained by blending a copolymer (X) comprising structural units (a), (b), and (c) with a phosphorus-containing compound (Y). Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group with 8 to 20 carbon atoms. Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxy group. Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group.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] Lubricating oils are blended with various lubricating oil additives for the purpose of imparting or supplementing the properties and performance required for lubricating oils. One of the typical lubricating oil additives is a load-bearing additive that imparts anti-wear and extreme pressure properties to the lubricating oil. As the load-bearing additive, for example, a low-molecular-weight phosphorus-based compound such as an amine phosphate is widely used (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-524930 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-124266 Summary of the Invention [Problem to be solved by the invention]

[0004] However, such low molecular weight phosphorus compounds often have insufficient wear resistance. Therefore, in recent years, various studies have been conducted on polymer-based compounds as load-bearing additives to replace low-molecular-weight phosphorus-based compounds (see, for example, Patent Document 2). However, polymer-based compounds that are being investigated as load-bearing additives often have insufficient extreme pressure properties compared to low-molecular-weight phosphorus-based compounds.

[0005] Therefore, an object of the present invention is to provide a lubricating oil additive composition that is suitable as a load-bearing additive and has excellent wear resistance and extreme pressure properties, and a lubricating oil composition containing the lubricating oil additive composition. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems. As a result, they discovered that a lubricating oil additive composition comprising a copolymer containing structural units derived from a plurality of specific monomers and a phosphorus-based compound can solve the above-mentioned problems. Based on the above findings, the present inventors have further conducted various studies and have completed the present invention.

[0007] According to the present invention, the following [1] to [4] are provided. [1] A copolymer (X) containing the following structural units (a), (b), and (c): A lubricating oil additive composition comprising a phosphorus-containing compound (Y). Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group [2] A lubricating oil composition comprising the lubricating oil additive composition according to [1] and a lubricating oil base oil. [3] A copolymer (X) containing the following structural units (a), (b), and (c): a phosphorus-containing compound (Y) and a lubricating oil additive composition. Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group [4] A copolymer (X) containing the following structural units (a), (b), and (c): A method for producing a lubricating oil composition, comprising the step of mixing a phosphorus-containing compound (Y) with a lubricating base oil. Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a lubricating oil additive composition that is suitable as a load-bearing additive and has excellent wear resistance and extreme pressure properties, and a lubricating oil composition containing the lubricating oil additive composition. DETAILED DESCRIPTION OF THE INVENTION

[0009] The upper and lower limits of the ranges described herein can be combined in any way. For example, if 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. In this specification, "(meth)acrylate" means acrylate or methacrylate, and other similar terms have the same meaning.

[0010] In the following description, the "copolymer (X)" and the "phosphorus-containing compound (Y)" will also be referred to as the "component (X)" and the "component (Y)", respectively.

[0011] [Embodiments of lubricating oil additive composition] The lubricating oil additive composition of this embodiment comprises a copolymer (X) containing the following structural units (a), (b), and (c) and a phosphorus-containing compound (Y). Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group In the present invention, for example, a composition defined as "a composition comprising a blend of component (X) and component (Y)" includes not only "a composition containing component (X) and component (Y)", but also "a composition containing, in place of at least one of component (X) and component (Y), a modified product of said component" and "a composition containing a reaction product obtained by reacting component (X) and component (Y)". The lubricating oil additive composition of the present invention may contain a diluent and other additives as long as the effects of the present invention are not significantly impaired.

[0012] The present inventors have conducted extensive research to solve the above problems, and as a result have found that a lubricating oil additive composition comprising a copolymer (X) containing a constituent unit (a) derived from the monomer (A), a constituent unit (b) derived from the monomer (B), and a constituent unit (c) derived from the monomer (C) and a phosphorus-containing compound (Y) has excellent wear resistance and extreme pressure properties. The reason why the lubricating oil additive composition of this embodiment has excellent wear resistance and extreme pressure properties is not clear, but is presumed to be due to the following mechanism. That is, it is presumed that the lubricating oil additive composition comprising the copolymer (X) and the phosphorus-containing compound (Y) has oil solubility (solubility in base oil (particularly mineral oil)) due to the inclusion of the structural unit (a), a multi-point adsorption polymer due to the inclusion of the structural unit (b), and a predetermined amount of "phosphorus" introduced into the side chain due to the inclusion of the structural unit (c) bonded to the phosphorus-containing compound (Y). More specifically, at the sliding part, the copolymer (X) is compressed, exposing the "phosphorus" introduced into the side chain, which reacts with the metal and facilitates the formation of a phosphorus film on the metal surface. Furthermore, since the lubricating oil additive composition of this embodiment allows the structural unit (c) and the phosphorus-containing compound (Y) to freely bond and dissociate, it is presumed that the phosphorus-containing compound (Y) dissociated from the structural unit (c) reacts with the metal surface, forming a denser phosphorus film and improving wear resistance and extreme pressure properties.

[0013] The monomer (A), the monomer (B), the monomer (C), and the phosphorus-containing compound (Y) will be described in detail below.

[0014] <Monomer (A)> The monomer (A) used in this embodiment has a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms. The structural unit (a) derived from the monomer (A) mainly functions to impart oil solubility (solubility in mineral oil) to the copolymer (X). The monomer (A) may be used alone or in combination of two or more types. Therefore, the copolymer (X) may contain either one type of structural unit (a) derived from the monomer (A) alone or two or more types.

[0015] The (meth)acryloyl group in the monomer (A) functions as a polymerizable functional group and may be either an acryloyl group or a methacryloyl group, but the (meth)acryloyl group in the monomer (A) is preferably an acryloyl group. When the (meth)acryloyl group in the monomer (A) is an acryloyl group, the flexibility of the copolymer (X) can be improved. Therefore, while introducing a large amount of the structural unit (b) containing a hydroxyl group to bring out multipoint adsorption, the hydroxyl groups can be oriented toward the inside of the copolymer (X), making it easier to exhibit oil solubility.

[0016] The monomer (A) also has an alkyl group having 8 to 20 carbon atoms. When the alkyl group has 8 to 20 carbon atoms, the oil solubility of the copolymer (X) can be easily ensured. Examples of alkyl groups having 8 to 20 carbon atoms include chain alkyl groups such as octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl groups, which may be linear or branched. Here, from the viewpoint of making it easier to ensure the oil solubility of the copolymer (X), the alkyl group preferably has 10 to 18 carbon atoms, more preferably 10 to 16 carbon atoms, and even more preferably 10 to 14 carbon atoms.

[0017] In this embodiment, from the viewpoint of improving the effects of the present invention, the monomer (A) preferably contains the monomer (A1) described below.

[0018] (Monomer (A1)) The monomer (A1) is a monomer represented by the following general formula (a-1). [ka]

[0019] The monomer (A1) may be used alone or in combination of two or more types. Therefore, the copolymer (X) may contain either one type of structural unit (a1) derived from the monomer (A1) alone or two or more types.

[0020] In the above general formula (a-1), R a1 is a hydrogen atom or a methyl group, that is, the monomer (A1) has an acryloyl group or a methacryloyl group as a polymerizable functional group. R a1 Monomers in which is a hydrogen atom and a methyl group are readily available, and since such monomers are highly reactive, they can also be easily polymerized. Here, in this embodiment, R a1 is preferably a hydrogen atom. That is, the monomer (A1) preferably has an acryloyl group as the polymerizable functional group. When the (meth)acryloyl group of the monomer (A1) is an acryloyl group, the flexibility of the copolymer (X) can be improved. Therefore, while introducing a large amount of the structural unit (b) containing a hydroxyl group to bring out multipoint adsorption, the hydroxyl groups can be oriented toward the inside of the copolymer (X), making it easier to exhibit oil solubility.

[0021] In the above general formula (a-1), R a2 represents an alkyl group having 8 to 20 carbon atoms. When the alkyl group has 8 to 20 carbon atoms, the oil solubility of the copolymer (X) can be easily ensured. R a2 Examples of the alkyl group having 8 to 20 carbon atoms that can be selected as the alkyl group for the monomer (A) include those mentioned above as the alkyl group constituting the monomer (A). These may be linear or branched. Here, from the viewpoint of making it easier to ensure the oil solubility of the copolymer (X), the alkyl group preferably has 10 to 18 carbon atoms, more preferably 10 to 16 carbon atoms, and even more preferably 10 to 14 carbon atoms.

[0022] In this embodiment, the content of the structural unit (a1) derived from the monomer (A1) is, based on all structural units (a) derived from the monomer (A), preferably 50 mol% to 100 mol%, more preferably 60 mol% to 100 mol%, even more preferably 70 mol% to 100 mol%, still more preferably 80 mol% to 100 mol%, and even more preferably 90 mol% to 100 mol%.

[0023] <Monomer (B)> The monomer (B) used in this embodiment has a (meth)acryloyl group and a hydroxyl group. The structural unit (b) derived from the monomer (B) functions to make the copolymer (X) a multi-point adsorption type copolymer, and is thought to contribute to improving the abrasion resistance. The monomer (B) may be used alone or in combination of two or more types. Therefore, the copolymer (X) may contain either one type of structural unit (b) derived from the monomer (B) alone or two or more types.

[0024] The (meth)acryloyl group of the monomer (B) functions as a polymerizable functional group and may be either an acryloyl group or a methacryloyl group, but the (meth)acryloyl group of the monomer (B) is preferably an acryloyl group. When the (meth)acryloyl group of the monomer (B) is an acryloyl group, the flexibility of the copolymer (X) can be improved. Therefore, while introducing a large amount of the structural unit (b) containing a hydroxyl group to bring out multipoint adsorption, the hydroxyl groups can be oriented toward the inside of the copolymer (X), making it easier to exhibit oil solubility.

[0025] In this embodiment, from the viewpoint of improving the effects of the present invention, the monomer (B) preferably contains the monomer (B1) described below.

[0026] (Monomer (B1)) The monomer (B1) is a monomer represented by the following general formula (b-1). [ka]

[0027] The monomer (B1) may be used alone or in combination of two or more types. Therefore, the copolymer (X) may contain either one type of structural unit (b-1) derived from the monomer (B1) alone or two or more types.

[0028] In the above general formula (b-1), R b1 is a hydrogen atom or a methyl group, that is, the monomer (B1) has an acryloyl group or a methacryloyl group as a polymerizable functional group. R b1 Monomers in which the substituent is other than a hydrogen atom or a methyl group are readily available, and since such monomers are highly reactive, they can also be easily polymerized. Here, in this embodiment, R b1 is preferably a hydrogen atom. That is, the monomer (B1) preferably has an acryloyl group as the polymerizable functional group. When the (meth)acryloyl group of the monomer (B1) is an acryloyl group, the flexibility of the copolymer (X) can be improved. Therefore, while introducing a large amount of the structural unit (b) containing a hydroxyl group can bring out multi-point adsorption, the hydroxyl groups can be oriented toward the inside of the copolymer (X), making it easier to exhibit oil solubility. In the above general formula (b-1), R b2 represents an alkylene group having 2 to 4 carbon atoms. When the alkylene group has 2 to 4 carbon atoms, the oil solubility and polarity of the copolymer (X) are well balanced, and the copolymer (X) can have both oil solubility and adsorbability to metals. Here, from the viewpoint of easily ensuring appropriate oil solubility and appropriate adsorption to metals, the alkylene group preferably has 2 to 3 carbon atoms, and more preferably 2 carbon atoms.

[0029] m represents an integer of 1 to 10. When m is an integer of 2 or more, a plurality of R b2 may be the same or different. b2 )m The bonding mode between the moieties represented by the formula (I) may be random bonding or block bonding, but from the viewpoint of ease of polymerization, random bonding is preferred. When m is 1 to 10, the monomer (B1) does not become a carboxylic acid, and -(OR b2 Since the polarity is not too high due to the influence of the )- moiety, the oil solubility of the copolymer (X) can be improved. Here, m is preferably 1 to 6, more preferably 1 to 4, even more preferably 1 to 2, and even more preferably 1, from the viewpoint of easily ensuring appropriate oil solubility.

[0030] In this embodiment, the content of the structural unit (b1) derived from the monomer (B1) is, based on all structural units of the structural unit (b) derived from the monomer (B), preferably 50 mol% to 100 mol%, more preferably 60 mol% to 100 mol%, even more preferably 70 mol% to 100 mol%, still more preferably 80 mol% to 100 mol%, and even more preferably 90 mol% to 100 mol%.

[0031] <Monomer (C)> The monomer (C) used in this embodiment has a (meth)acryloyl group and an amine group. The structural unit (c) derived from the monomer (C) functions to bond with and release from the phosphorus-containing compound (Y), and is thought to contribute to improving wear resistance and extreme pressure properties. The monomer (C) may be used alone or in combination of two or more types. Therefore, the copolymer (X) may contain either one type of structural unit (c) derived from the monomer (C) alone or two or more types.

[0032] The (meth)acryloyl group of the monomer (C) functions as a polymerizable functional group and may be either an acryloyl group or a methacryloyl group, but the (meth)acryloyl group of the monomer (C) is preferably an acryloyl group. When the (meth)acryloyl group of the monomer (C) is an acryloyl group, the flexibility of the copolymer (X) can be improved. Therefore, while introducing a large amount of the structural unit (b) containing a hydroxyl group to bring out multipoint adsorption, the hydroxyl groups can be oriented toward the inside of the copolymer (X), making it easier to exhibit oil solubility.

[0033] In this embodiment, the amine group refers to a monovalent functional group (-NH2, -NHR, -NRR') obtained by removing one hydrogen atom from ammonia, a primary amine, or a secondary amine. Here, R and R' each independently represent an alkyl group having 1 to 4 carbon atoms, and R and R' may be the same or different.

[0034] The amine group contained in the monomer (C) may be any of -NH2, -NHR, and -NRR'. However, from the viewpoint of improving the effects of the present invention, the amine group contained in the monomer (C) is preferably either -NHR or -NRR', and more preferably -NRR'.

[0035] In this embodiment, from the viewpoint of improving the effects of the present invention, the monomer (C) preferably contains the monomer (C1) described below.

[0036] (Monomer (C1)) The monomer (C1) is a monomer represented by the following general formula (c-1). [ka]

[0037] The monomer (C1) may be used alone or in combination of two or more types. Therefore, the copolymer (X) may contain either one type of structural unit (c-1) derived from the monomer (C1) alone or two or more types.

[0038] In the above general formula (c-1), R c1 is a hydrogen atom or a methyl group, that is, the monomer (C1) has an acryloyl group or a methacryloyl group as a polymerizable functional group. R c1 Monomers in which the substituent is other than a hydrogen atom or a methyl group are readily available, and since such monomers are highly reactive, they can also be easily polymerized. Here, in this embodiment, R c1 is preferably a hydrogen atom. That is, the monomer (C1) preferably has an acryloyl group as the polymerizable functional group. When the (meth)acryloyl group of the monomer (C1) is an acryloyl group, the flexibility of the copolymer (X) can be improved. Therefore, while introducing a large amount of the structural unit (b) containing a hydroxyl group to bring out multipoint adsorption, the hydroxyl groups can be oriented toward the inside of the copolymer (X), making it easier to exhibit oil solubility.

[0039] In the above general formula (c-1), R c2 represents an alkylene group having 2 to 4 carbon atoms. When the alkylene group has 2 to 4 carbon atoms, the oil solubility and polarity of the copolymer (X) are well balanced, and the copolymer (X) can have both oil solubility and adsorbability to metals. Here, from the viewpoint of easily ensuring appropriate oil solubility and appropriate adsorption to metals, the alkylene group preferably has 2 to 3 carbon atoms, and more preferably 2 carbon atoms.

[0040] n represents an integer of 1 to 10. When n is an integer of 2 or more, a plurality of R c2 may be the same or different. c2 ) nThe bonding mode between the moieties represented by the formula (I) may be random bonding or block bonding, but from the viewpoint of ease of polymerization, random bonding is preferred. When n is 1 to 10, the monomer (C1) does not become an amide, and -(OR c2 Since the polarity is not too high due to the influence of the )- moiety, the oil solubility of the copolymer (X) can be improved. Here, n is preferably 1 to 6, more preferably 1 to 4, even more preferably 1 to 2, and even more preferably 1, from the viewpoint of easily ensuring appropriate oil solubility.

[0041] In the above general formula (c-1), R c3 and R c4 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. When the number of carbon atoms in the alkyl group is 4 or less, the copolymer (X) has appropriate adsorption to metals. In addition, from the viewpoint of improving the effects of the present invention, R c3 and R c4 At least one of the groups is preferably an alkyl group having 1 to 4 carbon atoms, and it is more preferable that both of the groups are alkyl groups having 1 to 4 carbon atoms. Furthermore, from the viewpoint of improving the effects of the present invention, the alkyl group preferably has 1 to 3 carbon atoms, more preferably 1 to 2 carbon atoms, and even more preferably 1 carbon atom. R c3 and R c4 may be the same or different, but from the viewpoint of improving wear resistance and oxidation stability, and taking into consideration easy availability, it is preferable that they are the same.

[0042] In this embodiment, the content of the structural unit (c1) derived from the monomer (C1) is, based on all structural units (c) derived from the monomer (C), preferably 50 mol% to 100 mol%, more preferably 60 mol% to 100 mol%, even more preferably 70 mol% to 100 mol%, still more preferably 80 mol% to 100 mol%, and even more preferably 90 mol% to 100 mol%.

[0043] <Other monomers> In addition to the structural units (a), (b), and (c), the copolymer (X) may contain structural units derived from other monomers, provided that the effects of the present invention are not significantly impaired. Examples of such other monomers include functional group-containing monomers other than the monomers (A), (B), and (C). Examples of such other functional group-containing monomers include functional group-containing (meth)acrylates other than the monomers (A), (B), and (C). However, from the viewpoint of making it easier to exert the effects of the present invention, the total content of the structural units (a), (b), and (c) in the copolymer (X) is preferably from more than 50% by mass to 100% by mass, more preferably from 60% by mass to 100% by mass, even more preferably from 70% by mass to 100% by mass, still more preferably from 80% by mass to 100% by mass, and even more preferably from 90% by mass to 100% by mass, based on all the structural units in the copolymer (X). Furthermore, from the viewpoint of making it easier to exert the effects of the present invention, the content of structural units derived from functional group-containing monomers other than the monomers (A), (B), and (C) in the copolymer (X) is preferably 50% by mass or less, more preferably less than 40% by mass, even more preferably less than 30% by mass, still more preferably less than 20% by mass, and even more preferably less than 10% by mass, based on all structural units.

[0044] <Content of structural unit (a)> From the viewpoint of ensuring oil solubility and improving the effects of the present invention, the content of the structural unit (a) in the copolymer (X) is preferably 60% by mass or more, more preferably 60% by mass to 90% by mass, even more preferably 65% ​​by mass to 90% by mass, and still more preferably 70% by mass to 90% by mass, based on the total amount of the copolymer (X). Furthermore, from the viewpoint of ensuring oil solubility and improving the effects of the present invention, the content of the structural unit (a) in the copolymer (X) is preferably 50 mol% or more, more preferably 50 mol% to 90 mol%, even more preferably 50 mol% to 85 mol%, and still more preferably 50 mol% to 80 mol%, based on the total amount of the copolymer (X).

[0045] <Content of structural unit (b)> From the viewpoint of improving the effects of the present invention, the content of the structural unit (b) in the copolymer (X) is preferably 5% by mass or more, more preferably 5% by mass to 50% by mass, even more preferably 5% by mass to 40% by mass, and still more preferably 5% by mass to 30% by mass, based on the total amount of the copolymer (X). Furthermore, from the viewpoint of improving the effects of the present invention, the content of the structural unit (b) in the copolymer (X) is preferably 10 mol% or more, more preferably 10 mol% to 50 mol%, even more preferably 10 mol% to 40 mol%, and still more preferably 15 mol% to 40 mol%, based on the total amount of the copolymer (X).

[0046] <Content of structural unit (c)> From the viewpoint of improving the effects of the present invention, the content of the structural unit (c) in the copolymer (X) is preferably 0.1 mass% or more, more preferably 0.1 mass% to 10 mass%, even more preferably 0.5 mass% to 5 mass%, and still more preferably 0.8 mass% to 3.0 mass%, based on the total amount of the copolymer (X). Furthermore, from the viewpoint of improving the effects of the present invention, the content of the structural unit (c) in the copolymer (X) is preferably 0.1 mol % or more, more preferably 0.1 mol % to 10 mol %, even more preferably 0.5 mol % to 5 mol %, and still more preferably 0.8 mol % to 3.0 mol %, based on the total amount of the copolymer (X).

[0047] <Content ratio of each structural unit [(a) / (b)], [(a) / (c)], [(c) / ((a)+(b))]> In copolymer (X) of the present embodiment, from the viewpoint of improving the effects of the present invention and from the viewpoint of oil solubility, the content ratio of the structural unit (a) to the structural unit (b) [(a) / (b)], in mass ratio, is preferably 95 / 5 to 50 / 50, more preferably 95 / 5 to 60 / 40, and even more preferably 90 / 10 to 60 / 40. The content ratio of the structural unit (a) to the structural unit (c) [(a) / (c)], in mass ratio, is preferably 99.5 / 0.5 to 95 / 5, more preferably 99 / 1 to 95 / 5, and even more preferably 99 / 1 to 96 / 4. Furthermore, the content ratio of the structural unit (a), the structural unit (b), and the structural unit (c) [(c) / ((a)+(b))], in mass ratio, is preferably 0.5 / 99.5 to 5 / 95, more preferably 1 / 99 to 5 / 95, and even more preferably 1 / 99 to 4 / 96. Furthermore, in view of improving the effects of the present invention and oil solubility, the content ratio of the structural unit (a) to the structural unit (b) in the copolymer (X) of the present embodiment [(a) / (b)] is preferably 90 / 10 to 50 / 50, more preferably 80 / 20 to 50 / 50, and even more preferably 80 / 20 to 55 / 45, in molar ratio. The content ratio of the structural unit (a) to the structural unit (c) [(a) / (c)], in molar ratio, is preferably 99 / 1 to 94 / 6, more preferably 99 / 1 to 95 / 5, and even more preferably 98 / 2 to 95 / 5. Furthermore, the content ratio of the structural unit (a), the structural unit (b), and the structural unit (c) [(c) / ((a)+(b))], in molar ratio, is preferably 1 / 99 to 5 / 95, more preferably 1 / 99 to 4 / 96, and even more preferably 2 / 98 to 4 / 96.

[0048] <Amount of Copolymer (X)> The blending amount of copolymer (X) is adjusted so that the content of the resin component of copolymer (X) is preferably 20% by mass to 80% by mass, more preferably 30% by mass to 70% by mass, and even more preferably 40% by mass to 60% by mass, based on the total amount of the lubricating oil additive composition.

[0049] <Physical properties of copolymer (X)> (Mass average molecular weight (Mw), molecular weight distribution (Mw / Mn)) The mass average molecular weight (Mw) of the copolymer (X) of this embodiment is preferably 1,000 to 100,000, more preferably 3,000 to 50,000, and even more preferably 5,000 to 30,000, from the viewpoint of making it easier to exhibit the effects of the present invention and from the viewpoint of solubility in the base oil. From the viewpoint of more easily achieving the effects of the present invention, the molecular weight distribution (Mw / Mn) of the copolymer (X) of the present embodiment is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. The molecular weight distribution (Mw / Mn) of the copolymer (X) of the present embodiment may be 1.01 or more, 1.2 or more, or 1.3 or more. The mass average molecular weight (Mw) and molecular weight distribution (Mw / Mn) are values ​​measured or calculated by the method described in the examples below.

[0050] (Polymerization mode) The polymerization mode of the copolymer (X) of the present embodiment is not particularly limited, and may be any of block copolymerization, random copolymerization, and block / random copolymerization. Among these, random copolymerization is preferred from the viewpoint of ease of polymerization reaction.

[0051] <Phosphorus-containing compound (Y)> The lubricating oil additive composition of the present invention comprises a copolymer (X) and a phosphorus-containing compound (Y). By blending the copolymer (X) and the phosphorus-containing compound (Y), phosphorus atoms are introduced into the side chains of the copolymer (X), and the phosphorus-containing compound (Y) released from the copolymer (X) forms a dense phosphorus coating on the metal surface, thereby improving wear resistance and extreme pressure properties. The phosphorus-containing compound (Y) may be used alone or in combination of two or more.

[0052] In this embodiment, the phosphorus-containing compound (Y) preferably has at least one of a carboxyl group, a hydroxyl group, and a thiol group, from the viewpoint of facilitating bonding with the structural unit (c) in the copolymer (X). Examples of the phosphorus-containing compound (Y) used in this embodiment include phosphites, phosphates, phosphonates, and their amine salts or metal salts; thiophosphites, thiophosphates, thiophosphonates, and their amine salts or metal salts; and more specifically, phosphites, thiophosphites, phosphates, and thiophosphates, respectively, represented by the following general formula (y-1), and phosphonates and thiophosphonates, respectively, represented by the following general formula (y-2). Among these, the phosphorus-containing compound (Y) used in the present embodiment preferably contains one or more compounds selected from the group consisting of phosphate esters, thiophosphate esters, and thiophosphate esters having a terminal carboxyl group. The thiophosphate ester is more preferably a dithiophosphate ester containing two sulfur atoms. [ka]

[0053] In the above general formulas (y-1) and (y-2), R y11 , R y12 , and R y21 each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms; X 11 , X 12 , and X 21 each independently represents an oxygen atom or a sulfur atom, and y1 represents 2 or 3. In the above general formula (y-1), R y11 At least one of the R y2 At least one of the groups is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0054] R y11 , R y12 , and R y21From the viewpoint of improving wear resistance and oxidation stability, preferred examples of the monovalent hydrocarbon group include alkyl groups, alkenyl groups, cycloalkyl groups, and aryl groups. Aliphatic hydrocarbon groups such as alkyl groups, alkenyl groups, and cycloalkyl groups are more preferred, with alkyl groups and alkenyl groups being even more preferred, and alkyl groups being particularly preferred. When these monovalent hydrocarbon groups are alkyl groups or alkenyl groups, they may be either linear or branched. Furthermore, the cycloalkyl groups and aryl groups may be polycyclic groups such as decaryl groups, naphthyl groups, and groups having a bicyclo ring.

[0055] These monovalent hydrocarbon groups may have a substituent containing an oxygen atom, such as a hydroxyl group or a carboxyl group, or may be partially substituted with an oxygen atom, a halogen atom, or the like. When the monovalent hydrocarbon group is a cycloalkyl group or an aryl group, it may further have a substituent such as an alkyl group or an alkenyl group. R y11 , R y12 , and R y21 When there are a plurality of groups, they may all be hydrogen atoms, may be a combination of a hydrogen atom and a monovalent hydrocarbon group, or may all be hydrocarbon groups, and when there are a plurality of hydrocarbon groups, the hydrocarbon groups may be the same or different.

[0056] R y11 , R y12 , and R y21 When the monovalent hydrocarbon group is an alkyl group, the number of carbon atoms in the monovalent hydrocarbon group is preferably 1 or more, with the upper limit being preferably 12 or less, more preferably 6 or less, and even more preferably 4 or less, from the viewpoint of improving wear resistance and oxidation stability, and when the monovalent hydrocarbon group is an alkenyl group, the number of carbon atoms is preferably 2 or more, with the upper limit being preferably 12 or less, more preferably 6 or less, and even more preferably 4 or less. Furthermore, when the monovalent hydrocarbon group is a cycloalkyl group, the number of carbon atoms is preferably 5 or more and 20 or less, and when the monovalent hydrocarbon group is an aryl group, the number of carbon atoms is preferably 6 or more and 20 or less.

[0057] In this embodiment, from the viewpoint of improving the effects of the present invention, the phosphorus-containing compound (Y) preferably includes a phosphorus-containing compound (Y1) described below.

[0058] The phosphorus-containing compound (Y1) is a phosphate or thiophosphate represented by the following general formula (y-3). [ka]

[0059] In the above general formula (y-3), R y31 represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and X 31 and X 32 Each independently represents an oxygen atom or a sulfur atom. y31 At least one of them is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0060] The alkyl group may be either linear or branched. The alkyl group preferably has 1 to 7 carbon atoms, more preferably 1 to 5 carbon atoms, and even more preferably 1 to 4 carbon atoms. In the present embodiment, the "number of carbon atoms XX to YY" in the expression "a substituted or unsubstituted ZZ group having a carbon number of XX to YY" represents the number of carbon atoms when the ZZ group is unsubstituted, and does not include the number of carbon atoms of the substituent when the ZZ group is substituted. These alkyl groups may have a substituent containing an oxygen atom, such as a hydroxyl group or a carboxyl group, or may be partially substituted with an oxygen atom, a halogen atom, or the like. R y31 When there are a plurality of alkyl groups, they may all be hydrogen atoms, may be a combination of hydrogen atoms and alkyl groups, or may all be alkyl groups, and when there are a plurality of alkyl groups, the alkyl groups may be the same or different.

[0061] In this embodiment, from the viewpoint of improving the effects of the present invention, when the phosphorus-containing compound (Y1) does not contain a hydroxyl group or a thiol group, it preferably contains a phosphorus-containing compound (Y11) having a carboxyl group at its terminal, which will be described below.

[0062] The phosphorus-containing compound (Y11) having a terminal carboxyl group is a phosphate or thiophosphate represented by the following general formula (y-4).

[0063] [ka]

[0064] In the above general formula (y-4), R y41 represents an unsubstituted alkyl group having 1 to 10 carbon atoms, L represents a linear or branched alkylene group having 1 to 8 carbon atoms, and X 41 , X 42 , and X 43 each independently represents an oxygen atom or a sulfur atom.

[0065] From the viewpoint of improving solubility in the base oil, L is preferably a linear or branched alkylene group having 1 to 8 carbon atoms, and more preferably a linear or branched alkylene group having 2 to 4 carbon atoms. Specifically, preferred examples include -CH2CH2-, -CH2CH(CH3)-, -CH2CH(CH2CH3)-, CH2CH(CH3)CH2-, and -CH2CH(CH2CH2CH3)-, with -CH2CH(CH3)- and -CH2CH(CH3)CH2- being more preferred, and -CH2CH(CH3)- being even more preferred.

[0066] The alkyl group may be either linear or branched. The alkyl group preferably has 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms. R y41 When there are multiple alkyl groups, the alkyl groups may be the same or different.

[0067] In this embodiment, the phosphorus-containing compound (Y11) having a terminal carboxyl group may be either a phosphate ester or a thiophosphate ester, but is preferably a thiophosphate ester from the viewpoint of improving the effects of the present invention.

[0068] <Amount of Phosphorus-Containing Compound (Y)> The blending amount of the phosphorus-containing compound (Y) is adjusted so that the content of the resin component of the phosphorus-containing compound (Y) is preferably 0.1 to 3.0 mass%, more preferably 0.3 to 2.6 mass%, and even more preferably 0.5 to 2.3 mass%, based on the total amount of the lubricating oil additive composition.

[0069] [Method of manufacturing lubricating oil additive composition] The method for producing the lubricating oil additive composition of this embodiment includes the step of mixing a copolymer (X) containing the following structural units (a), (b), and (c) with a phosphorus-containing compound (Y): Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group

[0070] <Step (S) of Producing Copolymer (X)> The method for producing the copolymer (X) (polymerization method) is not particularly limited, and the copolymer (X) can be produced by any known method, such as emulsion polymerization, suspension polymerization, or solution polymerization. Here, from the viewpoint of the use of the copolymer (X) of the present invention, i.e., its use as a lubricating oil additive composition, it is preferable to adopt a solution polymerization method in which a solvent that dissolves in a lubricating base oil is used as a solvent for producing the copolymer (X) (polymerization method).

[0071] (solution polymerization method) The solution polymerization method is carried out, for example, by charging the monomers (A), (B), and (C), a solvent, and an initiator into a reactor, replacing the atmosphere in the reactor with nitrogen, and then stirring and reacting for 2 to 10 hours at 60 to 100° C. Monomers other than the monomers (A), (B), and (C) may also be charged into the reactor as desired.

[0072] Examples of solvents used in solution polymerization methods include alcohols such as methanol, ethanol, propanol, 2-propanol, and butanol; hydrocarbons such as benzene, toluene, xylene, and hexane; esters such as ethyl acetate, butyl acetate, and isobutyl acetate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ethers such as methoxybutanol, ethoxybutanol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, and dioxane; mineral oil; and synthetic oils such as poly-α-olefins, ethylene-α-olefin copolymers, alkylbenzenes, alkylnaphthalenes, polyphenyl ethers, alkyl-substituted diphenyl ethers, polyol esters, dibasic acid esters, hindered esters, monoesters, and GTL base oils. These may be used alone or in combination of two or more.

[0073] Examples of initiators used in the solution polymerization method include azo initiators such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis-(N,N-dimethyleneisobutylamidine) dihydrochloride, and 1,1'-azobis(cyclohexyl-1-carbonitrile); hydrogen peroxide; organic peroxides such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, methyl ethyl ketone peroxide, and perbenzoic acid; persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; and hydrogen peroxide-Fe. 2+ redox initiators; and other existing radical initiators.

[0074] The molecular weight of the copolymer (X) can be controlled by known methods, such as by adjusting the reaction temperature, reaction time, amount of initiator, amount of each monomer, type of solvent, use of a chain transfer agent, etc.

[0075] <Contents of Copolymer (X) and Phosphorus-Containing Compound (Y) 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 copolymer (X) and the phosphorus-containing compound (Y) 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. Considering the purity of the copolymer (X) and the phosphorus-containing compound (Y), the amount of the copolymer (X) and the phosphorus-containing compound (Y) 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 contents of the copolymer (X) and the phosphorus-containing compound (Y) in the lubricating oil additive composition refer to the contents based on the total amount of the active ingredients in the lubricating oil additive composition excluding the diluting solvent.

[0076] <Phosphorus Atom Content in Lubricating Oil Additive Composition> From the viewpoint of making it easier to exhibit the effects of the present invention when added to a lubricating base oil, the lubricating oil additive composition of this embodiment preferably has a phosphorus atom content of 0.01 to 3.00 mass%, more preferably 0.02 to 2.00 mass%, even more preferably 0.05 to 1.00 mass%, and still more preferably 0.10 to 0.50 mass%, based on the total amount of the lubricating oil additive composition.

[0077] <Uses of lubricating oil additive composition> The lubricating oil additive composition of this embodiment has excellent anti-wear properties and extreme pressure properties, and is therefore useful as a load-bearing additive. Therefore, in this embodiment, there is provided a method of using the lubricating oil additive composition as a load-bearing additive.

[0078] [Lubricating oil composition] The lubricating oil composition of this embodiment contains a lubricating oil additive composition containing copolymer (X) and a lubricating base oil. From the viewpoint of ensuring that the additive effect of the lubricating oil additive composition is satisfactorily exhibited, the content of the resin component of the lubricating oil additive composition is adjusted to preferably 0.3 mass % to 10 mass %, more preferably 0.4 mass % to 5.0 mass %, and even more preferably 0.5 mass % to 3.0 mass %, based on the total amount of the lubricating oil composition. Furthermore, from the viewpoint of favorably exhibiting the additive effect of the lubricating oil additive composition, the content of phosphorus atoms derived from the lubricating oil additive composition is preferably 300 ppm by mass or less, more preferably 10 ppm by mass to 300 ppm by mass, even more preferably 20 ppm by mass to 200 ppm by mass, still more preferably 25 ppm by mass to 150 ppm by mass, and even more preferably 30 ppm by mass to 100 ppm by mass, based on the total amount of the lubricating oil composition.

[0079] <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 lubricating base oil at 100°C is 1mm 2 / s~50mm 2 / s, and preferably in the range of 2 mm 2 / s~30mm 2 / s, and more preferably in the range of 3 mm 2 / s~20mm 2 It is more preferable that the ratio is in the range of / s. The viscosity index of the lubricating base oil is preferably 80 or greater, more preferably 90 or greater, and even more preferably 100 or greater. The kinematic viscosity and viscosity index of the lubricating base oil are values ​​measured or calculated in accordance with JIS K2283:2000.

[0080] 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.

[0081] <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 significantly 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.

[0082] (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.

[0083] (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.

[0084] (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.

[0085] (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.

[0086] (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.

[0087] (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.

[0088] (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.

[0089] [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 2.0 mm 2 / s~30mm 2 / s, more preferably 3.0 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 105 or greater. In this specification, the kinematic viscosity and viscosity index of a lubricating oil composition refer to values ​​measured in accordance with JIS K2283:2000.

[0090] (wear resistance) The lubricating oil composition of this embodiment preferably has a wear scar diameter of 0.50 mm or less, more preferably 0.46 mm or less, and even more preferably 0.42 mm or less, as determined by the Shell wear test described in the Examples below.

[0091] (Extreme pressure) The lubricating oil composition (new oil) of this embodiment preferably has a maximum non-seizure load (LNL) of 785 N or more, more preferably 981 N or more, as determined by the Shell four-ball load carrying capacity (EP) test described in the Examples below. The welding load (WL) measured by the same test is preferably 1569 N or more.

[0092] (Phosphorus atom content) To further improve the effects of the present invention, the phosphorus atom content in the lubricating oil composition of this embodiment is preferably 10 ppm by mass or more, more preferably 20 ppm by mass or more, and even more preferably 40 ppm by mass or more, based on the total amount (100% by mass) of the lubricating oil composition, and is preferably 300 ppm by mass or less, more preferably 200 ppm by mass or less, and even more preferably 100 ppm by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 10 ppm by mass to 300 ppm by mass, more preferably 20 ppm by mass to 200 ppm by mass, and even more preferably 40 ppm by mass to 100 ppm by mass. The phosphorus atom content can be measured in accordance with JPI-5S-38-03.

[0093] [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 a step of mixing the lubricating oil additive composition with a lubricating base oil. The method for mixing the lubricating oil additive composition with the lubricating base oil is not particularly limited, but may include, for example, a method including a step of blending the lubricating oil additive composition with the lubricating base oil. At this time, the other additives may also be blended at the same time. In addition, each component may be blended after being made into a solution (dispersion) by adding a diluent oil or the like. After blending the components, it is preferable to stir them by a known method to uniformly disperse them.

[0094] Another method for producing a lubricating oil composition according to this embodiment includes the step of mixing a copolymer (X) containing the following structural units (a), (b), and (c), a phosphorus-containing compound (Y), and a lubricating base oil: Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group In the above process, the copolymer (X), the phosphorus-containing compound (Y), and the lubricating base oil are not limited to being blended all at once. The copolymer (X) may be blended and mixed with the lubricating base oil, and then the phosphorus-containing compound (Y) may be blended and mixed, or the copolymer (Y) may be blended and mixed with the lubricating base oil, and then the copolymer (X) may be blended and mixed. Of course, the copolymer (X) and the phosphorus-containing compound (Y) may be blended and mixed simultaneously with the lubricating base oil. When the copolymer (X) and the phosphorus-containing compound (Y) are blended and mixed simultaneously with the lubricating base oil, it is preferable to blend the lubricating base oil with the lubricating additive composition of this embodiment. The copolymer (X) and the phosphorus-containing compound (Y) may be blended in the form of a solution (dispersion) by adding a diluent oil or the like, or may be blended in the form of a dispersion in the polymerization solvent used in the polymerization without removing the polymerization solvent.

[0095] [Uses of lubricating oil composition] The lubricating oil composition of this embodiment contains the copolymer (X) and the phosphorus-containing compound (Y), and therefore has excellent wear resistance and extreme pressure 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.

[0096] [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.

[0097] [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.

[0098] [One aspect of the present invention provided] In one aspect of the present invention, the following [1] to

[14] are provided. [1] A copolymer (X) containing the following structural units (a), (b), and (c): A lubricating oil additive composition comprising a phosphorus-containing compound (Y). Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group [2] The lubricating oil additive composition according to [1] above, wherein the structural unit (a) comprises a structural unit (a1) derived from a monomer (A1) represented by the following general formula (a-1): [ka] [In the above general formula (a-1), R a1 represents a hydrogen atom or a methyl group. a2 represents an alkyl group having 8 to 20 carbon atoms.] [3] The lubricating oil additive composition according to [1] or [2], wherein the structural unit (b) comprises a structural unit (b1) derived from a monomer (B1) represented by the following general formula (b-1): [ka] [In the above general formula (b-1), R b1 is a hydrogen atom or a methyl group. b2 represents an alkylene group having 2 to 4 carbon atoms. m represents an integer of 1 to 10. When m is an integer of 2 or more, multiple R b2 may be the same or different.] [4] The lubricating oil additive composition according to any one of the above [1] to [3], wherein the structural unit (c) comprises a structural unit (c1) derived from a monomer (C1) represented by the following general formula (c-1): [ka] [In the above general formula (c-1), R c1 is a hydrogen atom or a methyl group. c2 represents an alkylene group having 2 to 4 carbon atoms. n represents an integer of 1 to 10. When n is an integer of 2 or more, multiple R c2 may be the same or different. c3 and R c4 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. [5] The lubricating oil additive composition according to any one of the above [1] to [4], wherein the phosphorus-containing compound (Y) has at least one of a carboxyl group, a hydroxyl group, and a thiol group. [6] The lubricating oil additive composition according to [5] above, wherein the phosphorus-containing compound (Y) contains one or more compounds selected from the group consisting of phosphate esters, thiophosphate esters, and thiophosphate esters having a terminal carboxyl group. [7] The lubricating oil additive composition according to any one of the above [1] to [6], wherein the copolymer (X) has a mass average molecular weight of 1,000 to 100,000. [8] The lubricating oil additive composition according to any one of [1] to [7], wherein the content of the structural unit (c) is 0.1 mass% or more based on all structural units of the copolymer (X). [9] The lubricating oil additive composition according to any one of [1] to [8], wherein the phosphorus atom content in the lubricating oil additive composition is 0.01 to 3.00 mass% based on the total amount of the lubricating oil additive composition.

[10] The lubricating oil additive composition according to any one of the above [1] to [9], which is used as a load-bearing additive.

[11] A lubricating oil composition comprising the lubricating oil additive composition according to any one of the above [1] to

[10] and a lubricating oil base oil.

[12] The lubricating oil composition according to

[11] above, wherein the phosphorus atom content is 300 ppm by mass or less based on the total amount of the lubricating oil composition.

[13] A copolymer (X) containing the following structural units (a), (b), and (c): a phosphorus-containing compound (Y) and a lubricating oil additive composition. Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group

[14] A copolymer (X) containing the following structural units (a), (b), and (c): A method for producing a lubricating oil composition, comprising the step of mixing a phosphorus-containing compound (Y) with a lubricating base oil. Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group [Example]

[0099] The present invention will be specifically described with reference to the following examples, although the present invention is not limited to the following examples.

[0100] [Methods for measuring various physical properties] The properties of the raw materials used in each Example and Comparative Example and the lubricating oil compositions of each Example and Comparative Example were measured according to the procedures shown below.

[0101] (1)Kinematic viscosity, viscosity index Measured or calculated in accordance with JIS K2283:2000. (2) Mass average molecular weight (Mw), molecular weight distribution (Mw / Mn) Measurements were performed in accordance with JIS K7252-1:2016. One Tosoh Corporation column, "TSKguardcolumn SuperHZ-L," and two Tosoh Corporation columns, "TSKSuperMultipore HZ-M," were attached to a Waters "1515 Isocratic HPLC Pump" and a "2414 Refractive Index (RI) Detector," in that order from the upstream side. Measurements were performed under the following conditions: measurement temperature: 40°C, mobile phase: tetrahydrofuran, flow rate: 0.35 ml / min, sample concentration: 1.0 mg / ml, and the results were calculated in terms of standard polystyrene. (3) Phosphorus atom content The phosphorus atom content was measured in accordance with JPI-5S-38-03.

[0102] [Examples 1 to 3, Comparative Examples 1 to 4] The lubricating oil compositions shown in Table 1 were prepared by mixing the components below, and the following evaluations were carried out. The components used in preparing the lubricating oil compositions shown in Table 1 are described in detail below.

[0103] <Lubricant base oil> Mineral oil (150N) classified as Group II in the API classification

[0104] <Lubricating oil additive composition> Lubricating oil additive composition 1: Produced by the method described in Production Example 1. Lubricating oil additive composition 2: Produced by the method described in Production Example 2. Lubricating oil additive composition 3: Produced by the method described in Production Example 3. Lubricating oil additive composition 4: Produced by the method described in Comparative Production Example 1. Lubricating oil additive composition 5: Produced by the method described in Comparative Production Example 2. Amine phosphate: a mixture of dodecylamine / monomethyl phosphate and dimethyl phosphate = approximately 60 / 40 (mass ratio)

[0105] (Monomers used in Production Examples 1 to 3 and Comparative Production Example 1) "Dodecyl acrylate": In the above general formula (a-1), R a1 is a hydrogen atom, and R a2 is a dodecyl group (an alkyl group with 12 carbon atoms). It was used as monomer (A). "2-hydroxyethyl acrylate": In the above general formula (b-1), R b1 is a hydrogen atom, and R b2 is an ethylene group (an alkylene group having 2 carbon atoms) and m=1. It was used as monomer (B). "2-Dimethylaminoethyl acrylate": In the above general formula (c-1), R c1 is a hydrogen atom, and R c2 is an ethylene group (an alkylene group having two carbon atoms), n=1, and R c3 and R c4 is a methyl group (an alkyl group with one carbon atom). It was used as monomer (C).

[0106] (Phosphorus-containing compound (Y) used in Production Examples 1 to 3) Phosphorus-containing compound (Y)-1: Mixture of monomethyl phosphate and dimethyl phosphate In the general formula (y-3), (R y31 X 31 ) is a combination of two hydroxyl groups and one methoxy group or one hydroxyl group and two methoxy groups, and X 32 is a compound in which the oxygen atom is Phosphorus-containing compound (Y)-2: 3-[(diisobutoxyphosphorothioyl)sulfanyl]-2-methylpropanoic acid In the above general formula (y-4), (Ry41 X 41 ) are both isobutoxy groups, and X 42 and X 43 is a sulfur atom and L is -CH2CH(CH3)-. Phosphorus-containing compound (Y)-3: O,O-diethyl dithiophosphate In the general formula (y-3), (R y31 X 31 ) is a combination of one thiol group and two ethoxy groups, and X 32 is a compound in which the sulfur atom is

[0107] (Production Example 1: Production of lubricating oil additive composition 1) A 200 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer was charged with 36 g (150 mmol) of dodecyl acrylate, 11.5 g (99 mmol) of 2-hydroxyethyl acrylate, 0.944 g (6.59 mmol) of 2-dimethylaminoethyl acrylate, and 61 mL of 2-propanol as a solvent. Next, the atmosphere in the flask was replaced with nitrogen, and 0.2 g of 2,2'-azobis(isobutyronitrile) was added as an initiator. The temperature was then slowly raised with stirring, and the mixture was allowed to react for 4 hours under reflux at a temperature of 75 to 85°C, yielding a solution containing copolymer (X)-1. The copolymer (X)-1 had a mass average molecular weight (Mw) of 7,000 and a molecular weight distribution (Mw / Mn) of 1.43. Next, 0.74 g of phosphorus-containing compound (Y)-1 and 48 g of mineral oil were added to a solution containing 48 g of copolymer (X)-1, and the mixture was stirred. After that, 2-propanol was distilled off under reduced pressure to obtain lubricating oil additive composition 1. The phosphorus content of lubricating oil additive composition 1 was 0.20 mass %.

[0108] (Production Example 2: Production of Lubricating Oil Additive Composition 2) Lubricating oil additive composition 2 was obtained by carrying out the same procedure as in Production Example 1, except that 2.07 g of phosphorus-containing compound (Y)-2 was used instead of phosphorus-containing compound 1. The copolymer (X)-2 had a mass average molecular weight (Mw) of 7,000 and a molecular weight distribution (Mw / Mn) of 1.43. The phosphorus content of lubricating oil additive composition 2 was 0.19 mass %.

[0109] (Production Example 3: Production of Lubricating Oil Additive Composition 3) Lubricating oil additive composition 3 was obtained in the same manner as in Production Example 1, except that 1.18 g of phosphorus-containing compound (Y)-3 was used. The copolymer (X)-3 had a mass average molecular weight (Mw) of 7,000 and a molecular weight distribution (Mw / Mn) of 1.42. The phosphorus content of lubricating oil additive composition 3 was 0.19 mass %.

[0110] (Comparative Production Example 1: Production of Lubricating Oil Additive Composition 4) A 200 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer was charged with 36 g (150 mmol) of dodecyl acrylate, 11.5 g (99 mmol) of 2-hydroxyethyl acrylate, 0.944 g (6.59 mmol) of 2-dimethylaminoethyl acrylate, and 61 mL of 2-propanol as a solvent. Next, the atmosphere in the flask was replaced with nitrogen, and 0.2 g of 2,2'-azobis(isobutyronitrile) was added as an initiator. The temperature was then slowly raised with stirring, and the mixture was allowed to react for 4 hours under reflux at a temperature of 75 to 85°C, yielding a solution containing copolymer (X)-4. The copolymer (X)-4 had a mass average molecular weight (Mw) of 9,000 and a molecular weight distribution (Mw / Mn) of 1.53. Next, mineral oil was added to the solution containing copolymer (X)-4 to dilute it so that the content of copolymer (X)-4 was 50 mass% based on the total amount of copolymer (X)-4 and mineral oil, and after stirring, 2-propanol was distilled off under reduced pressure to obtain lubricating oil additive composition 4.

[0111] (Comparative Production Example 2: Production of Lubricating Oil Additive Composition 5) A 200 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer was charged with 36 g (150 mmol) of dodecyl acrylate, 11.5 g (99 mmol) of 2-hydroxyethyl acrylate, and 61 mL of 2-propanol as a solvent. Next, the atmosphere in the flask was replaced with nitrogen, and 0.2 g of 2,2'-azobis(isobutyronitrile) was added as an initiator. The temperature was then slowly raised with stirring, and the mixture was refluxed at 75-85°C for 4 hours to produce a solution containing copolymer (X')-1. The copolymer (X')-1 had a mass average molecular weight (Mw) of 13,000 and a molecular weight distribution (Mw / Mn) of 1.54. Next, mineral oil was added to the solution containing copolymer (X')-1 to dilute it so that the content of copolymer (X')-1 was 50 mass% based on the total amount of copolymer (X')-1 and mineral oil, and after stirring, 2-propanol was distilled off under reduced pressure to obtain lubricating oil additive composition 5.

[0112] [Evaluation method] The tests described below were carried out to evaluate the wear resistance and extreme pressure properties.

[0113] <Shell four-ball abrasion resistance test> The wear resistance of the lubricating oil compositions was evaluated using a Shell four-ball friction tester in accordance with ASTM D 4172 under test conditions of 294 N load, 1,200 rpm, 80°C temperature, and 30 minutes. The results were expressed as the wear scar diameter (mm) of the test ball. In this test, if the wear scar diameter was 0.42 mm or less, it was determined that the wear resistance was good.

[0114] <Shell four-ball load-bearing capacity (EP) test> The maximum non-seizure load (LNL) and weld load (WL) were measured using a high-speed four-ball friction tester at a rotation speed of 1,800 rpm and an oil temperature (room temperature: 25±5°C) in accordance with ASTM D 2783. The higher these values, the better the extreme pressure properties. In this test, if the maximum non-seizure load (LNL) was 981 N or more and the weld load (WL) was 1569 N or more, the extreme pressure properties were judged to be good.

[0115] The properties and evaluation results of each lubricating oil composition are shown in Table 1. [Table 1]

[0116] <Evaluation results> From Table 1, we can see the following: The results shown in Examples 1 to 3 show that the lubricating oil composition containing the lubricating oil additive composition obtained by blending the copolymer (X) and the phosphorus-containing compound (Y) has excellent wear resistance and extreme pressure properties. In contrast, the results shown in Comparative Example 1 reveal that the lubricating oil composition containing only the copolymer (X') that does not contain the structural unit (c) has insufficient extreme pressure properties. Furthermore, the results shown in Comparative Example 2 reveal that the lubricating oil composition containing only the phosphorus-containing compound (Y) has insufficient wear resistance. Furthermore, the results shown in Comparative Example 3 reveal that the lubricating oil composition containing the copolymer (X') not containing the structural unit (c) and the phosphorus-containing compound (Y) has insufficient wear resistance and extreme pressure properties. Furthermore, the results shown in Comparative Example 4 reveal that the lubricating oil composition containing only the copolymer (X) has insufficient extreme pressure properties.

Claims

1. A copolymer (X) containing the following structural units (a), (b), and (c); A lubricating oil additive composition comprising a phosphorus-containing compound (Y). Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group

2. The lubricating oil additive composition according to claim 1, wherein the structural unit (a) comprises a structural unit (a1) derived from a monomer (A1) represented by the following general formula (a-1): 【Chemical 1】 [In the above general formula (a-1), R ａ１ represents a hydrogen atom or a methyl group. ａ２ represents an alkyl group having 8 to 20 carbon atoms.

3. The lubricating oil additive composition according to claim 1 or 2, wherein the structural unit (b) comprises a structural unit (b1) derived from a monomer (B1) represented by the following general formula (b-1): 【Chemistry 2】 [In the above general formula (b-1), R ｂ１ is a hydrogen atom or a methyl group. ｂ２ represents an alkylene group having 2 to 4 carbon atoms. m represents an integer of 1 to 10. When m is an integer of 2 or more, a plurality of R ｂ２ may be the same or different.

4. The lubricating oil additive composition according to any one of claims 1 to 3, wherein the structural unit (c) comprises a structural unit (c1) derived from a monomer (C1) represented by the following general formula (c-1): 【Chemistry 3】 [In the above general formula (c-1), R ｃ１ is a hydrogen atom or a methyl group. ｃ２ represents an alkylene group having 2 to 4 carbon atoms. n represents an integer of 1 to 10. When n is an integer of 2 or more, a plurality of R ｃ２ may be the same or different. ｃ３ and R ｃ４ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

5. 5. The lubricating oil additive composition according to claim 1, wherein the phosphorus-containing compound (Y) has at least one of a carboxyl group, a hydroxyl group, and a thiol group.

6. 6. The lubricating oil additive composition according to claim 5, wherein the phosphorus-containing compound (Y) comprises at least one compound selected from the group consisting of a phosphate ester, a thiophosphate ester, and a thiophosphate ester having a terminal carboxyl group.

7. The lubricating oil additive composition according to any one of claims 1 to 6, wherein the copolymer (X) has a mass average molecular weight of 1,000 to 100,000.

8. The lubricating oil additive composition according to any one of claims 1 to 7, wherein the content of the structural unit (c) is 0.1 mass% or more based on all structural units of the copolymer (X).

9. The lubricating oil additive composition according to any one of claims 1 to 8, wherein the phosphorus atom content in the lubricating oil additive composition is 0.01 to 3.00 mass% based on the total amount of the lubricating oil additive composition.

10. The lubricating oil additive composition according to any one of claims 1 to 9, which is used as a load-bearing additive.

11. A lubricating oil composition comprising the lubricating oil additive composition according to any one of claims 1 to 10 and a lubricating base oil.

12. 12. The lubricating oil composition according to claim 11, wherein the phosphorus atom content is 300 ppm by mass or less, based on the total amount of the lubricating oil composition.

13. A copolymer (X) containing the following structural units (a), (b), and (c); a phosphorus-containing compound (Y) and a lubricating oil additive composition. Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group

14. A copolymer (X) containing the following structural units (a), (b), and (c); A method for producing a lubricating oil composition, comprising the step of mixing a phosphorus-containing compound (Y) with a lubricating base oil. Structural unit (a): a structural unit derived from a monomer (A) having a (meth)acryloyl group and an alkyl group having 8 to 20 carbon atoms Structural unit (b): a structural unit derived from a monomer (B) having a (meth)acryloyl group and a hydroxyl group Structural unit (c): a structural unit derived from a monomer (C) having a (meth)acryloyl group and an amine group

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