Additive composition for lubricating oil, method for producing additive composition for lubricating oil, lubricating oil composition, and method for producing lubricating oil composition

Abstract

To provide an additive composition for lubricating oil which exhibits a superior viscosity index improvement effect.SOLUTION: An additive composition for lubricating oil is obtained by blending a copolymer (X) having an alkyl group with 1 to 40 carbon atoms in a side chain and containing a phosphate group, with a copolymer (Y) having an alkyl group with 1 to 40 carbon atoms in a side chain and containing an amine group, wherein the copolymer (X) and the copolymer (Y) preferably include, as structural units independently contained therein, a structural unit (a1) derived from a monomer (A1) represented by the general formula (a-1). It is also preferable that the copolymer (X) includes, as a structural unit, a structural unit (b1) derived from a phosphorus-containing monomer (B1) represented by the general formula (b-1). It is further preferable that the copolymer (Y) includes, as a structural unit, a structural unit (c1) derived from an amine-containing monomer (C1) represented by the general formula (c-1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a lubricating oil additive composition, a method for producing a lubricating oil additive composition, a lubricating oil composition, and a method for producing a lubricating oil composition. [Background technology]

[0002] In recent years, lubricating oil compositions used as drive system oils such as automatic transmission fluids (ATFs), continuously variable transmission fluids (CVTFs), and shock absorber fluids (SAFs), as well as oils for internal combustion engines and equipment oils such as hydraulic oils, are required to have various properties depending on their respective applications. For example, in order to improve the fuel economy of automobiles, it is important to improve the automobile itself, such as by reducing the weight of the automobile and improving the engine, as well as to improve the lubricating oil, such as by reducing the viscosity of the lubricating oil composition to reduce viscous resistance and by adding various lubricating oil additives. However, since lubricating oil compositions are used over a wide temperature range, simply lowering the viscosity will result in a thinner oil film at the lubricated parts under high temperature conditions, which will cause problems such as increased wear and seizure due to contact between components. Therefore, it is desirable for the viscosity of the lubricating oil composition to remain as constant as possible over a wide temperature range. In other words, it is desirable for the lubricating oil composition to have a high viscosity index. Therefore, for lubricating oil compositions to be used over a wide temperature range from high to low temperatures, a method is generally used in which viscosity-adjusting additives such as viscosity index improvers and pour point depressants are added to improve the temperature dependency of viscosity.

[0003] For example, Patent Document 1 discloses a lubricating oil composition containing a composition (lubricating oil additive composition) in which a copolymer containing a diol group and a compound containing a boronic acid ester functional group are mixed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2017-508055 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the lubricating oil additive composition described in Patent Document 1 does not have a sufficient viscosity index improving effect, and there is room for further improvement.

[0006] Therefore, an object of the present invention is to provide a lubricating oil additive composition that has an excellent viscosity index improving effect, a method for producing the lubricating oil additive composition, and a lubricating oil composition containing the lubricating oil additive composition and a method for producing the lubricating oil composition. [Means for solving the problem]

[0007] According to the present invention, the following [1] to [4] are provided. [1] A copolymer (X) having an alkyl group having 1 to 40 carbon atoms in a side chain and containing a phosphate group; and a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in the side chain and containing an amine group. [2] A lubricating oil composition comprising the lubricating oil additive composition according to [1] above and a lubricating oil base oil. [3] A copolymer (X) having an alkyl group having 1 to 40 carbon atoms in a side chain and containing a phosphate group; a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing an amine group; [4] a lubricating base oil; a copolymer (X) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing a phosphate group; a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing an amine group; [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a lubricating oil additive composition that has an excellent viscosity index improving effect, a method for producing the lubricating oil additive composition, and a lubricating oil composition containing the lubricating oil additive composition, and a method for producing the lubricating oil composition. [Brief explanation of the drawings]

[0009] [Figure 1] 3 shows the 31P-NMR spectrum at each temperature when the temperature of the lubricating oil composition of Example 3 is increased in the order of 40°C, 60°C, 80°C, and 100°C. [Figure 2] For the lubricating oil composition of Example 3, the temperature was lowered in the order of 100°C, 80°C, 60°C, and 40°C after the measurement in Figure 1, and the 31P-NMR spectrum was obtained at each temperature. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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. The term "(meth)acrylate" means acrylate or methacrylate, and similar terms have similar meanings. For example, "poly(meth)acrylate" means polyacrylate or polymethacrylate.

[0011] [Embodiments of lubricating oil additive composition] The lubricating oil additive composition of this embodiment comprises a copolymer (X) having an alkyl group with 1 to 40 carbon atoms in the side chain and containing a phosphate group, and a copolymer (Y) having an alkyl group with 1 to 40 carbon atoms in the side chain and containing an amine group.

[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) having an alkyl group with 1 to 40 carbon atoms in its side chain and containing a phosphate group, and a copolymer (Y) having an alkyl group with 1 to 40 carbon atoms in its side chain and containing an amine group, has an excellent viscosity index improving effect. The reasons why the lubricating oil additive composition of this embodiment has an excellent viscosity index improving effect are presumed to be as follows (i) to (iii). (i) The viscosity of lubricating base oils tends to decrease as the temperature increases, and it is preferable that the rate of change in viscosity with temperature change be as small as possible. Here, the morphology of the polymer in the lubricating oil composition is also affected by temperature. At low temperatures, the polymer tends to take on an aggregated form, which reduces resistance to flow, thereby reducing the thickening effect of the polymer. On the other hand, when the lubricating oil composition is heated, the polymer aggregates are relaxed and tend to expand, increasing resistance to flow and enhancing the thickening effect of the polymer. Therefore, in a lubricating oil composition containing a polymer, the viscosity decrease of the base oil due to an increase in temperature can be compensated for by the thickening effect of the polymer, and the rate of viscosity decrease due to an increase in temperature in the entire lubricating oil composition can be reduced. (ii) The lubricating oil additive composition of this embodiment comprises a copolymer (X) having an alkyl group with 1 to 40 carbon atoms in the side chain and containing a phosphate group, and a copolymer (Y) having an alkyl group with 1 to 40 carbon atoms in the side chain and containing an amine group. At low temperatures, copolymer (X) and copolymer (Y) each take on an aggregated form, and therefore the phosphate group tends to be hidden in copolymer (X) and the amine group tends to be hidden in copolymer (Y), making it difficult for the functional groups to react, and the copolymers tend to remain mixed together. On the other hand, when the lubricating oil composition is heated, the aggregation of each polymer is relaxed and the polymer spreads, making it easier for functional groups to be exposed from the polymer. Therefore, the phosphate group in copolymer (X) and the amine group in copolymer (Y) are more likely to associate (ionic bond), making it easier to form a polymer complex. As a result, the formed polymer complex has a larger molecular weight than copolymer (X) and copolymer (Y) individually, making it easier for the viscosity to increase. Furthermore, when the temperature returns to low, the copolymers tend to aggregate again, which dissociates the ionic bonds in the polymer complex, making it easier for the copolymers to return to a mixed state and resulting in a low viscosity state. The present inventors have found that at low temperatures, copolymer (X) and copolymer (Y) tend to form separate, independent morphologies, while at high temperatures they tend to form a polymer complex, and that this morphology returns when the temperature is further reduced. In other words, the present inventors have found that the copolymers exhibit viscosity control effects even when subjected to repeated temperature changes. Based on this finding, the present inventors have found that the lubricating oil additive composition of this embodiment functions as a dynamic ionic polymer that exhibits reversible dynamic interactions (bonding-dissociation) in response to temperature changes. (iii) The lubricating oil additive composition of this embodiment exhibits an excellent viscosity index improving effect due to the combination of the above-mentioned (i) "effect due to the polymer form" and the above-mentioned (ii) "effect due to the ionic bond (association) between the phosphate group and the amine group."

[0013] In this embodiment, the term "a lubricating oil additive composition comprising a blend of copolymer (X) and copolymer (Y)" also encompasses the following aspects. "A lubricating oil additive composition comprising a copolymer (X) and a copolymer (Y)" "A lubricating oil additive composition comprising, instead of at least one of the components of copolymer (X) and copolymer (Y), a modified product of said component" "A lubricating oil additive composition containing a reaction product (complex) obtained by reacting copolymer (X) with copolymer (Y)"

[0014] The copolymer (X) and the copolymer (Y) will be described in detail below.

[0015] <Copolymer (X)> The copolymer (X) is a copolymer having an alkyl group having 1 to 40 carbon atoms in the side chain and containing a phosphate group. The copolymer (X) is a copolymer of a monomer having an alkyl group having 1 to 40 carbon atoms and a monomer containing a phosphate group.

[0016] The monomer having an alkyl group having 1 to 40 carbon atoms has a polymerizable functional group. Examples of the polymerizable functional group include one or more selected from an acryloyl group, a methacryloyl group, a styryl group, and an ethylenically unsaturated group. Among these, an acryloyl group and a methacryloyl group are preferred.

[0017] Examples of alkyl groups having 1 to 40 carbon atoms include chain alkyl groups such as methyl, ethyl, propyl, butyl, n-pentyl, n-hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl groups. These may be linear or branched. The alkyl group preferably has 2 to 30 carbon atoms, more preferably 4 to 20 carbon atoms, and even more preferably 8 to 16 carbon atoms, from the viewpoint that the fewer the carbon atoms, the more flexible the main chain becomes and the easier it is to improve the viscosity index.

[0018] Examples of the monomer having an alkyl group having 1 to 40 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-dodecyl (meth)acrylate, etc. Among these, n-dodecyl acrylate is preferred.

[0019] The monomer containing a phosphate group has a polymerizable functional group. Examples of the polymerizable functional group include one or more selected from an acryloyl group, a methacryloyl group, a styryl group, and an ethylenically unsaturated group. Among these, an acryloyl group and a methacryloyl group are preferred.

[0020] Examples of the phosphate group include a monovalent group obtained by removing one R from an alkoxy group (OR group) of a (neutral) phosphate ester. Examples of the phosphate group also include a monovalent group obtained by removing one hydrogen atom from a hydroxy group (OH group) of an acidic phosphate ester, and a monovalent group obtained by removing one R from an alkoxy group (OR group) of an acidic phosphate ester. Examples of the phosphate ester include triphenyl phosphate, tricresyl phosphate, benzyl diphenyl phosphate, ethyl diphenyl phosphate, tributyl phosphate, ethyl dibutyl phosphate, tert-butylphenyl diphenyl phosphate, di-tert-butylphenyl monophenyl phosphate, cresyl diphenyl phosphate, dicresyl monophenyl phosphate, ethylphenyl diphenyl phosphate, diethylphenyl monophenyl phosphate, triethylphenyl phosphate, trihexyl phosphate, tri(2-ethylhexyl) phosphate, tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tripalmityl phosphate, tristearyl phosphate, and trioleyl phosphate. Examples of the acidic phosphate ester include mono(di)ethyl acid phosphate, mono(di)n-propyl acid phosphate, mono(di)2-ethylhexyl acid phosphate, mono(di)butyl acid phosphate, mono(di)oleyl acid phosphate, mono(di)isodecyl acid phosphate, mono(di)isotridecyl acid phosphate, mono(di)lauryl acid phosphate, mono(di)stearyl acid phosphate, and mono(di)isostearyl acid phosphate.

[0021] (Structural unit (a1)) The copolymer (X) preferably contains a structural unit (a1) derived from a monomer (A1) represented by the following general formula (a-1), as a monomer having an alkyl group having 1 to 40 carbon atoms. [ka] [In the general formula (a-1), R a1 represents a hydrogen atom or a methyl group. a2 represents an alkyl group having 1 to 40 carbon atoms.]

[0022] When the copolymer (X) contains the structural unit (a1), the proportion of hydrophobic groups increases, which makes it possible to increase the solubility of the copolymer (X) in the base oil of the lubricating oil composition. R a1 Monomers in which R is a hydrogen atom or a methyl group are readily available and have high reactivity, so that they can be easily polymerized. Therefore, from the viewpoint of easily adjusting the molecular weight of the copolymer (X), a1 is preferably a hydrogen atom. That is, the monomer (A1) preferably has an acryloyl group as the polymerizable functional group. R a2 The fewer the carbon atoms, the more flexible the main chain becomes, and from the viewpoint of facilitating an improvement in viscosity index, the number of carbon atoms is preferably 2 to 30, more preferably 4 to 20, and even more preferably 8 to 16. These may be linear or branched. Specific alkyl groups are as described above.

[0023] The monomer (A1) may be used alone or in combination of two or more.

[0024] 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%.

[0025] (Structural unit (b1)) The copolymer (X) preferably contains a structural unit (b1) derived from a phosphorus-containing monomer (B1) represented by the following general formula (b-1). [ka] [In the general formula (b-1), R b1 is a hydrogen atom or a methyl group. b2 represents a linear or branched alkylene group having 2 to 4 carbon atoms. m1 represents an integer of 1 to 6. When m1 is an integer of 2 or more, multiple R b2 may be the same or different. n represents an integer of 1 or 2. When n=1, a plurality of R b3 At least one of R represents a hydrogen atom, and the remaining R b3 represents a hydrogen atom, a methyl group, or an ethyl group. When n=2, R b3 is a hydrogen atom.]

[0026] Preferred embodiments of each symbol in general formula (b-1) are shown below. R b1 is preferably a hydrogen atom from the viewpoint of improving the effects of the present invention. R b2 From the viewpoint of dynamic interactivity, examples of the linear or branched alkylene group having 2 to 4 carbon atoms that can be selected as include an ethylene group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, and a butane-2,2-diyl group. Among these, an ethylene group and a propane-1,2-diyl group are preferred. m1 is preferably 1 to 4, more preferably 1 to 2, from the viewpoint of improving the effects of the present invention. From the viewpoint of improving the effects of the present invention, n is preferably 1. When n=1, a plurality of R b3 At least one of R represents a hydrogen atom, and the remaining R b3 A hydrogen atom is also preferred. In addition, -(OR b2 ) m1 The bonding between the moieties represented by -O- may be random bonding or block bonding.

[0027] The monomer containing a phosphate group is not particularly limited, but examples thereof include compounds in which a polymerizable functional group and a phosphate group are bonded. Among these, (meth)acryloyloxyethyl acid phosphate is preferred.

[0028] The content of phosphorus atoms (P) in the copolymer (X) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, based on the total amount of the copolymer (X).

[0029] (Content of Structural Unit (a1) in Copolymer (X)) When copolymer (X) contains structural unit (a1), the content of structural unit (a1) derived from monomer (A1) is, in order to more easily enhance the viscosity index improving effect, preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on all structural units (100% by mass) of copolymer (X), and is preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 94% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the content is preferably 75% by mass to 98% by mass, more preferably 80% by mass to 96% by mass, and even more preferably 85% by mass to 94% by mass. Furthermore, when the copolymer (X) contains the structural unit (a1), the content of the structural unit (a1) derived from the monomer (A1) is, from the viewpoint of further enhancing the viscosity index improving effect, preferably 70 mol% or more, more preferably 75 mol% or more, and even more preferably 80 mol% or more, based on all structural units (100 mol%) of the copolymer (X). Also, it is preferably 98 mol% or less, more preferably 96 mol% or less, and even more preferably 93 mol% or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 70 mol % to 98 mol %, more preferably 75 mol % to 96 mol %, and even more preferably 80 mol % to 93 mol %.

[0030] (Content of Structural Unit (b1) in Copolymer (X)) When the copolymer (X) contains the structural unit (b1), the content of the structural unit (b1) derived from the phosphoric acid-containing monomer (B1) is, from the viewpoint of further enhancing the viscosity index improving effect, preferably 2% by mass or more, more preferably 4% by mass or more, and even more preferably 6% by mass or more, based on all structural units (100% by mass) of the copolymer (X). Also, it is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the content is preferably 2 to 25% by mass, more preferably 4 to 20% by mass, and even more preferably 6 to 15% by mass.

[0031] (Ratio of the structural unit (b1) to the structural unit (a1) in the copolymer (X) [(b1) / (a1)]) When copolymer (X) contains structural units (a1) and (b1), the content ratio of the structural unit (b1) derived from the phosphoric acid-containing monomer (B1) to the structural unit (a1) derived from the monomer (A1) [(b1) / (a1)] is, in terms of a mass ratio, preferably from 2 / 98 to 25 / 75, more preferably from 4 / 96 to 20 / 80, and even more preferably from 6 / 94 to 15 / 85, from the viewpoint of making it easier to enhance the viscosity index improving effect and from the viewpoint of making it easier to increase the solubility of copolymer (X) in the base oil. When copolymer (X) contains structural units (a1) and (b1), the content ratio of the structural unit (b1) derived from the phosphoric acid-containing monomer (B1) to the structural unit (a1) derived from the monomer (A1) [(b1) / (a1)] is, in terms of a molar ratio, preferably from 2 / 98 to 30 / 70, more preferably from 4 / 96 to 25 / 75, and even more preferably from 7 / 93 to 18 / 82, from the viewpoint of making it easier to enhance the viscosity index improving effect and to make it easier to improve the solubility of copolymer (X) in the base oil.

[0032] (Other structural units in copolymer (X)) In addition to the structural units (a1) and (b1), 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 (A1) and (B1). However, from the viewpoint of making it easier to exert the effects of the present invention, the total content of the structural units (a1) and (b1) in the copolymer (X) is preferably 80% by mass to 100% by mass, more preferably 90% by mass to 100% by mass, and even more preferably 95% by mass to 100% by mass, based on the total amount of the copolymer (X).

[0033] (Physical properties of copolymer (X)) The mass average molecular weight (Mw) of the copolymer (X) is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 15,000 or more, from the viewpoint of more easily enhancing the viscosity index improving effect, and is preferably 70,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less, from the viewpoint of more easily improving the shear stability of the copolymer (X). The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 5,000 to 70,000, more preferably 10,000 to 60,000, and even more preferably 15,000 to 50,000.

[0034] The molecular weight distribution (Mw / Mn) of the copolymer (X) is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The lower limit of the molecular weight distribution (Mw / Mn) of the copolymer (X) is not particularly limited, but is usually 1.01 or more.

[0035] The mass average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the copolymer (X) are values ​​measured by the method described in the examples below.

[0036] (Polymerization mode of copolymer (X)) The polymerization mode of the copolymer (X) is not particularly limited, and may be any of block copolymerization, random copolymerization, and block / random copolymerization, with random copolymerization being preferred.

[0037] <Copolymer (Y)> The copolymer (Y) is a copolymer having an alkyl group having 1 to 40 carbon atoms in the side chain and containing an amine group. The copolymer (Y) is a copolymer of a monomer having an alkyl group having 1 to 40 carbon atoms and a monomer containing an amine group.

[0038] The monomer having an alkyl group having 1 to 40 carbon atoms has a polymerizable functional group. Examples of the polymerizable functional group include one or more selected from an acryloyl group, a methacryloyl group, a styryl group, and an ethylenically unsaturated group. Among these, an acryloyl group and a methacryloyl group are preferred.

[0039] Examples of alkyl groups having 1 to 40 carbon atoms include chain alkyl groups such as methyl, ethyl, propyl, butyl, n-pentyl, n-hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosyl groups. These may be linear or branched. The alkyl group preferably has 2 to 30 carbon atoms, more preferably 4 to 20 carbon atoms, and even more preferably 8 to 16 carbon atoms, from the viewpoint that the fewer the carbon atoms, the more flexible the main chain becomes and the easier it is to improve the viscosity index.

[0040] Examples of the monomer having an alkyl group having 1 to 40 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-dodecyl (meth)acrylate, etc. Among these, n-dodecyl acrylate is preferred.

[0041] The amine group-containing monomer has a polymerizable functional group. Examples of the polymerizable functional group include one or more selected from an acryloyl group, a methacryloyl group, a styryl group, and an ethylenically unsaturated group. Among these, an acryloyl group and a methacryloyl group are preferred.

[0042] In this embodiment, examples of the amine group include ammonia, primary amines, and monovalent functional groups (-NH2, -NHR, -NRR') in which one hydrogen atom has been removed from a secondary amine. In the above-mentioned —NHR, R represents an alkyl group having 1 to 4 carbon atoms. In addition, in the above-mentioned -NRR', R and R' each independently represent an alkyl group having 1 to 4 carbon atoms.

[0043] The amine group may be any of -NH2, -NHR, and -NRR', but from the viewpoint of improving the effects of the lubricating oil composition of the present invention, the amine group possessed by the monomer is preferably either -NHR or -NRR', and more preferably -NRR'.

[0044] (Structural unit (a1)) The copolymer (Y) preferably contains a structural unit (a1) derived from a monomer (A1) represented by the following general formula (a-1), as a monomer having an alkyl group having 1 to 40 carbon atoms. [ka] [In the general formula (a-1), R a1 represents a hydrogen atom or a methyl group. a2 represents an alkyl group having 1 to 40 carbon atoms.]

[0045] When the copolymer (Y) contains the structural unit (a1), the proportion of hydrophobic groups increases, which makes it possible to increase the solubility of the copolymer (Y) in the base oil of the lubricating oil composition. R a1 Monomers in which R is a hydrogen atom or a methyl group are readily available and have high reactivity, so that they can be easily polymerized. Therefore, from the viewpoint of easily adjusting the molecular weight of the copolymer (X), a1 is preferably a hydrogen atom. That is, the monomer (A1) preferably has an acryloyl group as the polymerizable functional group. R a2 The fewer the carbon atoms, the more flexible the main chain becomes, and from the viewpoint of facilitating an improvement in viscosity index, the number of carbon atoms is preferably 2 to 30, more preferably 4 to 20, and even more preferably 8 to 16. These may be linear or branched. Specific alkyl groups are as described above.

[0046] The monomer (A1) may be used alone or in combination of two or more.

[0047] 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%.

[0048] The structural unit (a1) contained in the copolymer (Y) can be the same as the structural unit (a1) contained in the copolymer (X). From the viewpoint of making it easier to improve the solubility of the lubricating oil additive composition of this embodiment in the base oil, it is preferable that both the copolymer (X) and the copolymer (Y) contain the structural unit (a1). Furthermore, when both the copolymer (X) and the copolymer (Y) contain the structural unit (a1), the structural units (a1) contained in the copolymer (X) and the copolymer (Y) may be the same or different.

[0049] (structural unit (c1)) The copolymer (Y) preferably contains a structural unit (c1) derived from an amine-containing monomer (C1) represented by the following general formula (c-1). [ka] [In the general formula (c-1), R c11 is a hydrogen atom or a methyl group. c12 represents a linear or branched alkylene group having 2 to 4 carbon atoms. m2 represents an integer of 1 to 10. When m2 is an integer of 2 or more, multiple R c12 may be the same or different. c13 and R c14 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.]

[0050] Preferred embodiments of each symbol in general formula (c-1) are shown below. R c11 is preferably a hydrogen atom from the viewpoint of improving the effects of the present invention. R c12 From the viewpoint of the balance between oil solubility and polarity, examples of the linear or branched alkylene group having 2 to 4 carbon atoms that can be selected as the alkylene group include an ethylene group, a propane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, and a butane-2,2-diyl group. Of these, an ethylene group and a propane-1,2-diyl group are preferred. m2 is preferably 1 to 4, more preferably 1 to 2, from the viewpoint of dynamic interactivity. Rc13 and R c14 From the viewpoint of dynamic interactivity, is preferably a methyl group or an ethyl group, more preferably a methyl group. In addition, -(OR c12 ) m2 The bonding between the moieties represented by - may be either random bonding or block bonding, but from the viewpoint of ease of polymerization, random bonding is preferred.

[0051] The amine group-containing monomer is not particularly limited, but examples thereof include compounds in which a polymerizable functional group and an amine acid group are bonded. Of these, 2-dimethylaminoethyl acrylate is preferred.

[0052] The content of nitrogen atoms (N) in the copolymer (Y) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.6% by mass or more, based on the total amount of the copolymer (Y).

[0053] (Content of Structural Unit (a1) in Copolymer (Y)) When copolymer (Y) contains structural unit (a1), the content of structural unit (a1) derived from monomer (A1) is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on all structural units (100% by mass) of copolymer (Y), from the viewpoint of more easily enhancing the viscosity index improving effect and more easily improving the solubility of copolymer (Y) in base oil. Also, it is preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 94% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the content is preferably 75% by mass to 98% by mass, more preferably 80% by mass to 96% by mass, and even more preferably 85% by mass to 94% by mass. Furthermore, when copolymer (Y) contains structural unit (a1), the content of structural unit (a1) derived from monomer (A1) is, from the viewpoint of further enhancing the viscosity index improving effect, preferably 64 mol% or more, more preferably 70 mol% or more, and even more preferably 77 mol% or more, based on all structural units (100 mol%) of copolymer (Y). Also, it is preferably 97 mol% or less, more preferably 93 mol% or less, and even more preferably 90 mol% or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 64 mol % to 97 mol %, more preferably 70 mol % to 93 mol %, and even more preferably 77 mol % to 90 mol %.

[0054] (Content of Structural Unit (c1) in Copolymer (Y)) When copolymer (Y) contains structural unit (c1), the content of structural unit (c1) derived from amine-containing monomer (C1) is preferably 2% by mass or more, more preferably 4% by mass or more, and even more preferably 6% by mass or more, based on all structural units (100% by mass) of copolymer (Y), from the viewpoint of further enhancing the viscosity index improving effect, and is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the content is preferably 2 to 25% by mass, more preferably 4 to 20% by mass, and even more preferably 6 to 15% by mass. Furthermore, when copolymer (Y) contains structural unit (c1), the content of structural unit (c1) derived from amine-containing monomer (C1) is, from the viewpoint of further enhancing the viscosity index improving effect, preferably 3 mol% or more, more preferably 7 mol% or more, and even more preferably 10 mol% or more, based on all structural units (100 mol%) of copolymer (Y). Also, it is preferably 36 mol% or less, more preferably 30 mol% or less, and even more preferably 23 mol% or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 3 mol % to 36 mol %, more preferably 7 mol % to 30 mol %, and even more preferably 10 mol % to 23 mol %.

[0055] (Ratio of the structural unit (c1) to the structural unit (a1) in the copolymer (Y) [(c1) / (a1)]) When copolymer (Y) contains structural units (a1) and (c1), the content ratio of the structural unit (c1) derived from the amine-containing monomer (C1) to the structural unit (a1) derived from the monomer (A1) [(c1) / (a1)] is, in terms of a mass ratio, preferably from 2 / 98 to 25 / 75, more preferably from 4 / 96 to 20 / 80, and even more preferably from 6 / 94 to 15 / 85, from the viewpoint of making it easier to enhance the viscosity index improving effect and to make it easier to improve the solubility of copolymer (Y) in the base oil. When copolymer (Y) contains structural units (a1) and (c1), the content ratio of the structural unit (c1) derived from the amine-containing monomer (C1) to the structural unit (a1) derived from the monomer (A1) [(c1) / (a1)] is, in terms of a molar ratio, preferably from 3 / 97 to 36 / 64, more preferably from 7 / 93 to 30 / 70, and even more preferably from 10 / 90 to 23 / 77, from the viewpoint of making it easier to enhance the viscosity index improving effect and to make it easier to improve the solubility of copolymer (Y) in the base oil.

[0056] (Other structural units in copolymer (Y)) In addition to the structural units (a1) and (c1), copolymer (Y) 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 monomers (A1) and (C1). However, from the viewpoint of making it easier to exert the effects of the present invention, the total content of the structural units (a1) and (c1) in copolymer (Y) is preferably 80% by mass to 100% by mass, more preferably 90% by mass to 100% by mass, and even more preferably 95% by mass to 100% by mass, based on the total amount of copolymer (Y).

[0057] (Physical properties of copolymer (Y)) The mass average molecular weight (Mw) of the copolymer (Y) is preferably 2,000 or more, more preferably 3,000 or more, and even more preferably 4,000 or more, from the viewpoint of more easily enhancing the viscosity index improving effect, and is preferably 50,000 or less, more preferably 30,000 or less, and even more preferably 10,000 or less, from the viewpoint of more easily improving the shear stability of the copolymer (X). The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the range is preferably 2,000 to 50,000, more preferably 3,000 to 30,000, and even more preferably 4,000 to 10,000.

[0058] The molecular weight distribution (Mw / Mn) of the copolymer (Y) is preferably 3.0 or less, more preferably 2.5 or less, even more preferably 2.0 or less, and even more preferably 1.8 or less. The lower limit of the molecular weight distribution (Mw / Mn) of the copolymer (Y) is not particularly limited, but is usually 1.01 or more.

[0059] The mass average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the copolymer (Y) are values ​​measured by the method described in the examples below.

[0060] (Polymerization mode of copolymer (Y)) The polymerization mode of the copolymer (Y) is not particularly limited, and may be any of block copolymerization, random copolymerization, and block / random copolymerization, but from the viewpoint of ease of polymerization, a random copolymer is preferred.

[0061] (Protected Copolymer (Y)) The protected copolymer (Y) may be a copolymer (Y) ionically bonded to an acidic phosphate ester. Since amine groups are easily oxidized, ionically bonding with an acidic phosphate ester makes the amine groups less susceptible to oxidation, thereby improving oxidation stability. Examples of acidic phosphate esters include mono(di)ethyl acid phosphate, mono(di)n-propyl acid phosphate, mono(di)2-ethylhexyl acid phosphate, mono(di)butyl acid phosphate, mono(di)oleyl acid phosphate, mono(di)isodecyl acid phosphate, mono(di)isotridecyl acid phosphate, mono(di)lauryl acid phosphate, mono(di)stearyl acid phosphate, and mono(di)isostearyl acid phosphate. The acidic phosphate ester preferably has the following structure: [ka] n represents an integer of 1 or 2.

[0062] <Total Content of Copolymer (X) and Copolymer (Y) in Lubricating Oil Additive Composition> The lubricating oil additive composition of the present embodiment may or may not contain a lubricating oil additive composition other than the copolymer (X) and the copolymer (Y), as long as the effects of the present invention are not significantly impaired. However, from the viewpoint of making it easier to exhibit the effects of the present invention when added to a lubricating base oil, the total content of copolymer (X) and copolymer (Y) is preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, still more preferably 80 mass% or more, even more preferably 90 mass% or more, and even more preferably 95 mass% or more, based on the total amount of the lubricating oil additive composition. In addition, taking into consideration the purity of the copolymer (X) and the copolymer (Y), the total content of the copolymer (X) and the copolymer (Y) is usually less than 100 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 ease of handling. The total content of copolymer (X) and copolymer (Y) in the lubricating oil additive composition means the content based on the total amount of the active ingredients (resin components) in the lubricating oil additive composition excluding the diluting solvent. As the dilution solvent, it is preferable to use the same solvent as the polymerization solvent described below.

[0063] <Content ratio of copolymer (X) and copolymer (Y) in the lubricating oil additive composition> In the lubricating oil additive composition of this embodiment, the blending ratio of the copolymer (X) to the copolymer (Y) [(X) / (Y)] is, in terms of mass ratio, preferably 1 / 7 to 7 / 1, more preferably 1 / 5 to 5 / 1, even more preferably 1 / 3 to 3 / 1, and still more preferably 1 / 2 to 2 / 1, from the viewpoint of facilitating an enhancement of the viscosity index improving effect.

[0064] The copolymer (X) contains phosphoric acid, and the copolymer (Y) contains an amine. The ratio of the content of phosphorus atoms (P) to the content of nitrogen atoms (N) [(P) / (N)] is preferably 1 / 7 to 7 / 1, more preferably 1 / 5 to 5 / 1, and even more preferably 1 / 3 to 3 / 1, in mass ratio.

[0065] <Method for producing copolymer (X) and copolymer (Y)> The copolymer (X) and the copolymer (Y) can be produced independently by polymerizing the above-mentioned monomers in a polymerization solvent. The method for producing (polymerizing) the copolymer (X) and the copolymer (Y) is not particularly limited, and they can be produced by any known method, such as emulsion polymerization, suspension polymerization, solution polymerization, etc. Among these, from the viewpoint of application as a lubricating oil additive composition, the solution polymerization method using a solvent that dissolves in the lubricating base oil as the solvent is preferred.

[0066] (solution polymerization method) When copolymer (X) and copolymer (Y) are each independently produced by solution polymerization, they can be obtained by polymerizing each of the above-mentioned monomers, and, if necessary, other monomers, in a polymerization solvent using a polymerization initiator. The solution polymerization method can be carried out, for example, by charging the monomers (A1), (B1), and (C1), 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° C. to 100° C. Monomers other than the monomers (A1), (B1), and (C1) may also be charged into the reactor.

[0067] Examples of solvents 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.

[0068] The polymerization initiator may be, for example, one or more selected from the group consisting of an azo initiator, a peroxide initiator, a redox initiator, and an organic halogen compound initiator. The polymerization initiator used for polymerizing the copolymer (X) and the copolymer (Y) is preferably one or more selected from an azo initiator and a peroxide initiator, more preferably one or more selected from an azo initiator and an organic peroxide, and even more preferably an azo initiator. Examples of the azo polymerization initiator include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid) and salts thereof (e.g., hydrochloride salts), dimethyl 2,2'-azobisisobutyrate, 2,2'-azobis(2-amidinopropane) hydrochloride, and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

[0069] Examples of peroxide initiators include inorganic peroxides and organic peroxides. Examples of inorganic peroxides include hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate. Examples of organic peroxides include benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide, succinic acid peroxide, di(2-ethoxyethyl)peroxydicarbonate, tert-butyl peroxypivalate, tert-hexyl peroxypivalate, tert-butyl peroxyneoheptanoate, tert-butyl peroxyneodecanoate, tert-butyl peroxy 2-ethylhexanoate, tert-butyl peroxyisobutyrate, tert-amyl peroxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate, dibutyl peroxytrimethyladipate, and lauryl peroxide.

[0070] Examples of redox initiators include those comprising a combination of a reducing agent such as an alkali metal sulfite or bisulfite (e.g., ammonium sulfite, ammonium bisulfite, etc.), ferrous chloride, ferrous sulfate, or ascorbic acid, and an oxidizing agent such as an alkali metal persulfate, ammonium persulfate, hydrogen peroxide, or an organic peroxide. Furthermore, as described above, when the conversion rate of the constituent monomers does not reach 98% during polymerization of the copolymer (X) and the copolymer (Y), the conversion rate can be increased to the above-mentioned conversion rate by, for example, further adding additional polymerization initiator to the polymerization system.

[0071] During the polymerization, a known chain transfer agent may be used as necessary for the purpose of adjusting the physical properties of the copolymer, such as the molecular weight. Examples of chain transfer agents include mercaptans, thiocarboxylic acids, secondary alcohols such as isopropanol, amines such as dibutylamine, hypophosphites such as sodium hypophosphite, chlorine-containing compounds, and alkylbenzene compounds. Examples of mercaptans include alkyl mercaptan compounds having an alkyl group having 2 to 20 carbon atoms, such as n-butyl mercaptan, isobutyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, sec-butyl mercaptan, tert-butyl mercaptan, and tert-dodecyl mercaptan; and hydroxyl group-containing mercaptan compounds, such as mercaptoethanol and mercaptopropanol. Examples of thiocarboxylic acids include thioglycolic acid and thiomalic acid. The amounts of the polymerization initiator and chain transfer agent used can be appropriately selected in consideration of the desired physical properties of the copolymer (for example, adjustment of the molecular weight, etc.).

[0072] The polymerization can be controlled by adiabatic polymerization or temperature-controlled polymerization. The reaction temperature during polymerization is preferably 30 to 140°C, more preferably 50 to 130°C, and even more preferably 70 to 120°C. In addition to the method of initiating polymerization by heat, it is also possible to employ a method of initiating polymerization by irradiation with radiation, electron beams, ultraviolet rays, etc. The preferred method is a temperature-controlled solution polymerization method. The copolymerization may be in the form of block copolymerization, random copolymerization, or block / random copolymerization, but from the viewpoint of ease of polymerization, a random copolymer is preferred.

[0073] <Complex> In the lubricating oil additive composition of this embodiment, the copolymer (X) and the copolymer (Y) react with each other to form a reaction product (polymer composite). In the lubricating oil additive composition of this embodiment, the phosphate group-containing copolymer (X) and the amine group-containing copolymer (Y) are in an aggregated form at low temperatures in the lubricating oil composition, with the phosphate group hidden in the copolymer (X) and the amine group hidden in the copolymer (Y). On the other hand, in the lubricating oil additive composition of this embodiment, when the lubricating oil composition is heated, the aggregation of each polymer is relaxed and spread, so that the phosphate group in copolymer (X) and the amine group in copolymer (Y) are exposed. Therefore, the phosphate group in copolymer (X) and the amine group in copolymer (Y) can associate (by ionic bond) with each other to form a polymer complex. The polymer composite has a larger molecular weight than each of the copolymer (X) and the copolymer (Y), and therefore can enhance the viscosity index improving effect.

[0074] Furthermore, in the lubricating oil additive composition of this embodiment, when the lubricating oil composition returns to a low temperature, the copolymers aggregate again, causing the ionic bonds in the polymer complex to dissociate, separating into copolymer (X) and copolymer (Y), and returning to a mixed state of copolymer (X) and copolymer (Y). Therefore, the viscosity of the lubricating oil composition can be made lower than when the polymer complex was formed.

[0075] The lubricating oil additive composition of this embodiment is in the state of copolymer (X) and copolymer (Y) at low temperatures, and forms a polymer complex at high temperatures. That is, the lubricating oil additive composition of this embodiment exhibits reversible dynamic interaction due to temperature changes, and becomes a dynamic ion-binding polymer that undergoes bonding and dissociation. In this embodiment, the polymer conjugate is formed by the formation of a phosphate-amine ionic bond. By using this polymer as a lubricating oil additive composition, the viscosity of the lubricating oil composition can be controlled by temperature, and the viscosity can be repeatedly controlled even when the temperature changes repeatedly.

[0076] (Method for confirming complex formation) In the lubricating oil additive composition of this embodiment, a method for confirming whether a polymer complex is formed or not can be performed, for example, by the method described in the examples below. 31 This can be confirmed by analyzing the P-NMR spectrum.

[0077] [Method of manufacturing lubricating oil additive composition] The method for producing the lubricating oil additive composition of this embodiment is not particularly limited, but preferably includes, for example, a step of blending a phosphoric acid-containing copolymer (X) having an alkyl group with 1 to 40 carbon atoms in its side chain with an amine-containing copolymer (Y) having an alkyl group with 1 to 40 carbon atoms in its side chain.

[0078] [Uses of lubricating oil additive composition] The lubricating oil additive composition of this embodiment is not particularly limited, and can be used, for example, as a viscosity index improver or a pour point depressant. Of these, it is preferably used as a viscosity index improver.

[0079] [Embodiments of Lubricating Oil Composition] The lubricating oil composition of this embodiment preferably contains the lubricating oil additive composition of this embodiment and a lubricating base oil.

[0080] In the lubricating oil composition of this embodiment, the total content of the lubricating oil additive composition and the lubricating base oil is, based on the total amount (100 mass%) of the lubricating oil composition, preferably 60 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, and even more preferably 90 mass% or more, and is usually 100 mass% or less, preferably less than 100 mass%, more preferably 99 mass% or less, and even more preferably 98 mass% or less.

[0081] The content of the lubricating oil additive composition (equivalent to the resin content) is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on the total amount (100% by mass) of the lubricating oil composition, from the viewpoint of more easily exerting the viscosity index improving effect. Also, from the viewpoint of lowering the viscosity of the lubricating oil composition, it is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 12% by mass or less. The upper and lower limits of these numerical ranges can be combined arbitrarily. Specifically, the content is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and even more preferably 3 to 12% by mass.

[0082] <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.

[0083] 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.

[0084] The kinematic viscosity of the lubricating base oil at 40°C is preferably 6mm 2 / s~100mm 2 / s, more preferably 8 mm 2 / s~80mm 2 / s, more preferably 10 mm 2 / s~60mm 2 / s. The kinematic viscosity of lubricating base oil at 100°C is 1mm 2 / s~50mm 2 / s is preferred, 2 mm 2 / s~30mm 2 / s is more preferable, 3mm 2 / s~20mm 2 / s is more preferred. 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.

[0085] When the lubricating base oil contains mineral oil, the content of the mineral oil in the lubricating base oil is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, and even more preferably 70% by mass to 100% by mass, based on the total amount of the lubricating base oil.

[0086] <Other additives> The lubricating oil composition of this embodiment may further contain one or more additives selected from the group consisting of metal detergents, antiwear agents, ashless dispersants, extreme pressure agents, antioxidants, pour point depressants, antifoaming agents, surfactants or demulsifiers, friction modifiers, oiliness improvers, rust inhibitors, and metal deactivators (hereinafter also referred to as "other additives"), to the extent that the effects of the lubricating oil additive composition of this embodiment are not impaired. The other additives may be provided, for example, as an additive package for the lubricating oil composition. When the lubricating oil composition of the present embodiment contains other additives, the content of each of the other additives is, for example, preferably 0.001 to 15 mass%, more preferably 0.005 to 10 mass%, and even more preferably 0.01 to 8 mass%, based on the total amount (100 mass%) of the lubricating oil composition. Furthermore, when the lubricating oil composition of this embodiment contains other additives, the total content of the other additives is preferably more than 0 mass% and not more than 30 mass%, more preferably 0.001 to 25 mass%, even more preferably 0.001 to 20 mass%, and still more preferably 0.001 to 15 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0087] (Metallic detergents) Examples of metal-based detergents include organic acid metal salt compounds containing a metal atom selected from alkali metals and alkaline earth metals. Specific examples include metal salicylates, metal phenates, and metal sulfonates, each containing a metal atom selected from alkali metals and alkaline earth metals. In this specification, the term "alkali metal" refers to lithium, sodium, potassium, rubidium, cesium, and francium. Additionally, the term "alkaline earth metal" refers to beryllium, magnesium, calcium, strontium, and barium. As the metal atom contained in the metallic detergent, sodium, calcium, magnesium or barium is preferred, and calcium is more preferred, from the viewpoint of improving detergency at high temperatures.

[0088] Among the metallic detergents, one or more selected from calcium salicylate, calcium phenate, and calcium sulfonate are preferred from the viewpoints of improving detergency at high temperatures and solubility in the base oil.

[0089] The metal detergent may be a neutral salt, a basic salt, an overbased salt, or a mixture thereof. The total base number of the metallic detergent is preferably 0 to 600 mgKOH / g. When the metallic detergent is a basic salt or an overbased salt, the total base number of the metallic detergent is preferably 10 to 600 mgKOH / g, more preferably 20 to 500 mgKOH / g. In this specification, the term "base number" refers to the base number measured by the perchloric acid method in accordance with 7. of JIS K2501:2003 "Petroleum products and lubricants - Test method for neutralization number."

[0090] When the lubricating oil composition of this embodiment contains a metallic detergent as another additive, the content of the metallic detergent is preferably 0.01 to 10 mass % based on the total amount (100 mass %) of the lubricating oil composition. The metallic detergents may be used alone or in combination of two or more.

[0091] (anti-wear agent) Examples of anti-wear agents include sulfur-containing compounds such as zinc dialkyldithiophosphate (ZnDTP), zinc phosphate, disulfides, sulfurized olefins, sulfurized fats and oils, sulfurized esters, thiocarbonates, thiocarbamates, and polysulfides; phosphorus-containing compounds such as phosphites, phosphate esters, phosphonate esters, and amine salts or metal salts thereof; and sulfur- and phosphorus-containing anti-wear agents such as thiophosphites, thiophosphate esters, thiophosphonate esters, and amine salts or metal salts thereof. Of these, zinc dialkyldithiophosphate (ZnDTP) is preferred. When the lubricating oil composition of this embodiment contains an anti-wear agent as another additive, the content of the anti-wear agent is preferably 0.05 to 5.0 mass % based on the total amount (100 mass %) of the lubricating oil composition. The anti-wear agents may be used singly or in combination of two or more.

[0092] (Ashless dispersant) Examples of ashless dispersants include succinimide, benzylamine, succinic acid esters, and boron-modified versions of these, with alkenyl succinimide and boron-modified alkenyl succinimide being preferred.

[0093] Examples of the alkenyl succinimide include alkenyl succinic acid monoimide represented by the following general formula (i) and alkenyl succinic acid bisimide represented by the following general formula (ii). The alkenyl succinimide may be a modified alkenyl succinimide obtained by reacting a compound represented by the following general formula (i) or (ii) with one or more compounds selected from the group consisting of alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds, and organic acids: Furthermore, examples of the boron-modified alkenyl succinimide include boron-modified compounds represented by the following general formula (i) or (ii).

[0094] [ka]

[0095] In the general formulas (i) and (ii), R A , R A1 and R A2 are each independently an alkenyl group having a mass average molecular weight (Mw) of 500 to 3,000 (preferably 1,000 to 3,000), and are preferably a polybutenyl group or a polyisobutenyl group. R B , R B1 and R B2 are each independently an alkylene group having 2 to 5 carbon atoms. x1 is an integer of 1 to 10, preferably an integer of 2 to 5, and more preferably 3 or 4. x2 is an integer of 0 to 10, preferably an integer of 1 to 4, and more preferably 2 or 3.

[0096] The ratio of boron atoms to nitrogen atoms [B / N] constituting the boron-modified alkenyl succinimide is preferably 0.5 or more, more preferably 0.6 or more, even more preferably 0.8 or more, and still more preferably 0.9 or more, from the viewpoint of improving detergency. When the lubricating oil composition of this embodiment contains an ashless dispersant as another additive, the content of the ashless dispersant is preferably 0.1 to 20 mass % based on the total amount (100 mass %) of the lubricating oil composition. The ashless dispersants may be used alone or in combination of two or more.

[0097] (extreme pressure agent) Examples of extreme pressure agents include sulfur-based extreme pressure agents such as sulfides, sulfoxides, sulfones, and thiophosphinates, halogen-based extreme pressure agents such as chlorinated hydrocarbons, organometallic extreme pressure agents, and phosphorus-based extreme pressure agents. Furthermore, among the above-mentioned antiwear agents, compounds that function as extreme pressure agents can also be used. When the lubricating oil composition of this embodiment contains an extreme pressure agent as another additive, the content of the extreme pressure agent is preferably 0.1 to 10 mass % based on the total amount (100 mass %) of the lubricating oil composition. The extreme pressure agents may be used alone or in combination of two or more.

[0098] (antioxidant) From the viewpoint of improving oxidation stability, the lubricating oil composition of this embodiment preferably contains an antioxidant as another additive. The antioxidant can be selected from known antioxidants that have conventionally been used as antioxidants for lubricating oils, and examples thereof include amine-based antioxidants and phenol-based antioxidants. Examples of the amine-based antioxidant include diphenylamine-based antioxidants such as diphenylamine and alkylated diphenylamines having an alkyl group with 3 to 20 carbon atoms; and naphthylamine-based antioxidants such as α-naphthylamine, phenyl-α-naphthylamine, and substituted phenyl-α-naphthylamines having an alkyl group with 3 to 20 carbon atoms. Examples of phenolic antioxidants include monophenolic antioxidants such as 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; diphenolic antioxidants such as 4,4′-methylenebis(2,6-di-tert-butylphenol) and 2,2′-methylenebis(4-ethyl-6-tert-butylphenol); and hindered phenolic antioxidants. In the present embodiment, these antioxidants may be contained alone or in any combination of two or more. When the lubricating oil composition of this embodiment contains an antioxidant as another additive, the content of the antioxidant is preferably 0.05 to 7 mass%, more preferably 0.10 to 5 mass%, and even more preferably 0.15 to 3 mass%, based on the total amount (100 mass%) of the lubricating oil composition.

[0099] (pour point depressants) Examples of pour point depressants include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates (PMAs; polyalkyl(meth)acrylates, etc.), polyvinyl acetate, polybutene, and polyalkylstyrenes, with polymethacrylates being preferred. When the lubricating oil composition of this embodiment contains a pour point depressant as another additive, the content of the pour point depressant is preferably 0.01% by mass to 10% by mass based on the total amount (100% by mass) of the lubricating oil composition. The pour point depressants may be used alone or in combination of two or more.

[0100] (Antifoaming agent) Examples of the antifoaming agent include silicone-based antifoaming agents such as dimethylpolysiloxane, fluorine-based antifoaming agents such as fluorosilicone oil and fluoroalkyl ether, and polyacrylate-based antifoaming agents. When the lubricating oil composition of this embodiment contains an antifoaming agent as another additive, the content of the antifoaming agent is preferably 0.05 to 5 mass % based on the total amount (100 mass %) of the lubricating oil composition. The antifoaming agents may be used alone or in combination of two or more.

[0101] (Surfactant or demulsifier) Examples of surfactants or demulsifiers include polyalkylene glycol-based nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and polyoxyethylene alkyl naphthyl ethers. When the lubricating oil composition of this embodiment contains a surfactant or a demulsifier as other additives, the content of the surfactant or the demulsifier is preferably 0.01% by mass to 3% by mass, each independently based on the total amount (100% by mass) of the lubricating oil composition. These surfactants or demulsifiers may be used alone or in combination of two or more.

[0102] (friction modifier) Examples of friction modifiers include molybdenum-based friction modifiers such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdenum acid; ashless friction modifiers such as aliphatic amines, fatty acid esters, fatty acid amides, fatty acids, fatty alcohols, and aliphatic ethers, each having at least one alkyl or alkenyl group having 6 to 30 carbon atoms in the molecule; oils and fats, amines, amides, sulfurized esters, phosphate esters, phosphites, and phosphate amine salts. When the lubricating oil composition of this embodiment contains a friction modifier as another additive, the content of the friction modifier is preferably 0.05 to 4 mass % based on the total amount (100 mass %) of the lubricating oil composition. The friction modifiers may be used alone or in combination of two or more.

[0103] (oil improver) Examples of oiliness improvers include saturated or unsaturated aliphatic monocarboxylic acids such as stearic acid and oleic acid; polymerized fatty acids such as dimer acid and hydrogenated dimer acid; hydroxy fatty acids such as ricinoleic acid and 12-hydroxystearic acid; saturated or unsaturated aliphatic monoalcohols such as lauryl alcohol and oleyl alcohol; saturated or unsaturated aliphatic monoamines such as stearylamine and oleylamine; saturated or unsaturated aliphatic monocarboxylic acid amides such as lauric acid amide and oleic acid amide; and partial esters of polyhydric alcohols such as glycerin and sorbitol with saturated or unsaturated aliphatic monocarboxylic acids. When the lubricating oil composition of this embodiment contains an oiliness improver as another additive, the content of the oiliness improver is preferably 0.01% by mass to 5% by mass based on the total amount (100% by mass) of the lubricating oil composition. The oiliness improver may be used alone or in combination of two or more.

[0104] (rust inhibitor) Examples of the rust inhibitor include fatty acids, alkenyl succinic acid half esters, fatty acid soaps, alkyl sulfonates, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, and alkyl polyoxyethylene ethers. When the lubricating oil composition of this embodiment contains a rust inhibitor as another additive, the content of the rust inhibitor is preferably 0.01% by mass to 3% by mass based on the total amount (100% by mass) of the lubricating oil composition. The rust inhibitors may be used alone or in combination of two or more.

[0105] (Metal deactivator) Examples of metal deactivators include benzotriazole-based compounds, tolyltriazole-based compounds, thiadiazole-based compounds, imidazole-based compounds, and pyrimidine-based compounds. When the lubricating oil composition of this embodiment contains a metal deactivator as another additive, the content of the metal deactivator is preferably 0.01% by mass to 5% by mass based on the total amount (100% by mass) of the lubricating oil composition. The metal deactivators may be used alone or in combination of two or more.

[0106] [Physical properties of lubricating oil composition] <Kinematic viscosity, viscosity index> The lubricating oil composition of this embodiment preferably has a kinematic viscosity at 40°C of 10mm 2 / s~100mm 2 / s, more preferably 8 mm 2 / s~80mm 2 / s, more preferably 6 mm 2 / s~60mm 2 / s. The lubricating oil composition of this embodiment 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 150 or greater, more preferably 160 or greater, and even more preferably 165 or greater. The kinematic viscosity and viscosity index of the lubricating oil composition are values ​​measured or calculated in accordance with JIS K2283:2000.

[0107] [Method of manufacturing lubricating oil composition] The method for producing the lubricating oil composition of this embodiment is not particularly limited, but may include, for example, a method for producing a lubricating oil composition comprising the step of blending a lubricating base oil, a phosphoric acid-containing copolymer (X) having an alkyl group with 1 to 40 carbon atoms on its side chain, and an amine-containing copolymer (Y) having an alkyl group with 1 to 40 carbon atoms on its side chain.

[0108] In the above step, the lubricating base oil, the copolymer (X), and the copolymer (Y) 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 copolymer (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 copolymer (Y) may be blended and mixed simultaneously with the lubricating base oil. When the copolymer (X) and the copolymer (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 copolymer (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 a polymerization solvent without removing the polymerization solvent used in the polymerization.

[0109] The method for producing the lubricating oil composition of the present embodiment may or may not further include a step of blending additives other than the lubricating oil additive composition of the present embodiment into the lubricating base oil, as described above. When the other additives are blended into the lubricating base oil, the other additives may be blended in the form of a solution (dispersion) by adding a diluent oil or the like. Alternatively, the lubricating oil additive composition of this embodiment may be blended with a lubricating base oil, and the lubricating oil additive composition of this embodiment and other additives other than the lubricating oil additive composition may be blended together. In the method for producing a lubricating oil composition of this embodiment, preferred embodiments of the lubricating base oil, copolymer (X) and copolymer (Y) are as described above.

[0110] [Uses of lubricating oil composition] The lubricating oil composition of this embodiment contains the lubricating oil additive composition of this embodiment, and therefore has an excellent viscosity index improving effect. Therefore, the lubricating oil composition of this 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; equipment oils such as hydraulic oil, turbine oil, and compressor oil; fluid bearing oils; rolling bearing oils; and refrigeration oils.

[0111] [Lubrication method using lubricating oil composition] A lubrication method using the lubricating oil composition of this embodiment includes filling the lubricating oil composition of this embodiment into equipment used for each of the above-mentioned applications and lubricating the components of each of the equipment.

[0112] [One aspect of the present invention provided] According to one aspect of the present invention, the following [1] to

[13] are provided. [1] A copolymer (X) having an alkyl group having 1 to 40 carbon atoms in a side chain and containing a phosphate group; and a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in the side chain and containing an amine group. [2] The lubricating oil additive composition according to [1] above, wherein at least one of the copolymer (X) and the copolymer (Y) contains a structural unit (a1) derived from a monomer (A1) represented by the following general formula (a-1) as a monomer having an alkyl group having 1 to 40 carbon atoms: [ka] [In the general formula (a-1), R a1 represents a hydrogen atom or a methyl group.a2 represents an alkyl group having 1 to 40 carbon atoms.] [3] The lubricating oil additive composition according to [1] or [2] above, wherein the copolymer (X) contains a structural unit (b1) derived from a phosphorus-containing monomer (B1) represented by the following general formula (b-1): [ka] [In the general formula (b-1), R b1 is a hydrogen atom or a methyl group. b2 represents a linear or branched alkylene group having 2 to 4 carbon atoms. m1 represents an integer of 1 to 6. When m1 is an integer of 2 or more, multiple R b2 may be the same or different. n represents an integer of 1 or 2. When n=1, a plurality of R b3 At least one of R represents a hydrogen atom, and the remaining R b3 represents a hydrogen atom, a methyl group, or an ethyl group. When n=2, R b3 is a hydrogen atom.] [4] The lubricating oil additive composition according to any one of the above [1] to [3], wherein the copolymer (Y) contains a structural unit (c1) derived from an amine-containing monomer (C1) represented by the following general formula (c-1): [ka] [In the general formula (c-1), R c11 is a hydrogen atom or a methyl group. c12 represents a linear or branched alkylene group having 2 to 4 carbon atoms. m2 represents an integer of 1 to 10. When m2 is an integer of 2 or more, multiple R c12 may be the same or different. c13 and R c14 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 [1] to [4], wherein the blending ratio of the copolymer (X) to the copolymer (Y) [(X) / (Y)] is 1 / 7 to 7 / 1 in mass ratio. [6] The lubricating oil additive composition according to any one of [1] to [5] above, wherein the content of phosphorus atoms (P) is 0.1 mass% or more based on the total amount of the copolymer (X). [7] The lubricating oil additive composition according to any one of [1] to [6] above, wherein the content of nitrogen atoms (N) is 0.1 mass% or more based on the total amount of the copolymer (Y). [8] The lubricating oil additive composition according to any one of the above [1] to [7], wherein the ratio of the content of phosphorus atoms (P) to the content of nitrogen atoms (N) [(P) / (N)] is 1 / 7 to 7 / 1 in mass ratio. [9] The lubricating oil additive composition according to any one of the above [1] to [8], which is used as a viscosity index improver.

[10] A lubricating oil composition comprising the lubricating oil additive composition according to any one of [1] to [9] above and a lubricating oil base oil.

[11] The lubricating oil composition according to

[10] , further comprising one or more additives selected from the group consisting of metal-based detergents, anti-wear agents, ashless dispersants, extreme pressure agents, antioxidants, pour point depressants, anti-foaming agents, surfactants or demulsifiers, friction modifiers, oiliness improvers, rust inhibitors, and metal deactivators.

[12] A copolymer (X) having an alkyl group having 1 to 40 carbon atoms in a side chain and containing a phosphate group; a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing an amine group;

[13] a lubricating base oil; a copolymer (X) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing a phosphate group; a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing an amine group; [Example]

[0113] The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0114] [Method of measuring 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.

[0115] (1) Kinematic viscosity and viscosity index The 40°C kinematic viscosity, 100°C kinematic viscosity and viscosity index of the base oil and lubricating oil composition were measured or calculated in accordance with JIS K2283:2000.

[0116] (2) Mass average molecular weight (Mw), molecular weight distribution (Mw / Mn) 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 values ​​were calculated in terms of standard polystyrene.

[0117] [Monomer preparation and synthesis] First, the compounds described below were prepared and synthesized as monomers.

[0118] <n-ドデシルアクリレート> n-Dodecyl acrylate is the following compound: n-Dodecyl acrylate is a compound represented by the general formula (a-1), R a1 is a hydrogen atom, and R a2 is a linear alkyl group having 12 carbon atoms, Monomer (A1). [ka]

[0119] The following n-dodecyl acrylate was used: Product name: Dodecyl acrylate (manufactured by Fujifilm Wako Chemical Co., Ltd.)

[0120] <Monomers containing phosphoric acid> The following compounds were used as the phosphoric acid-containing monomers. The monomer having phosphoric acid is represented by the general formula (b-1), R b1 is a hydrogen atom, and R b2 is a linear alkylene group having 2 carbon atoms, m1 is 1, n is 1, and two R b3 is a hydrogen atom. [ka]

[0121] The following phosphoric acid-containing monomers were used: Product name: Light Acrylate P-1A(N) (Kyoeisha Chemical Co., Ltd.)

[0122] <Monomers containing amines> The following compounds were used as amine-containing monomers. The amine-containing monomer is a monomer represented by the general formula (c-1), R c11 is a hydrogen atom, and R c12 is a linear alkylene group having 2 carbon atoms, m2 is 1, and R c13 and R c14 is an amine-containing monomer (C1), which is an alkyl group having one carbon atom. [ka]

[0123] The following amine-containing monomers were used: Product name: 2-(dimethylamino)ethyl acrylate (Tokyo Chemical Industry Co., Ltd.)

[0124] <Protected Monomer> The following compounds were used as monomers having an amine protected with an acidic phosphate ester. [ka] n represents an integer of 1 or 2.

[0125] The amine-containing monomers are the same as those described above. The acidic phosphate esters used were as follows: Product name: JP-518-O (manufactured by Johoku Chemical Industry Co., Ltd.)

[0126] [Production of Copolymer A, Copolymer B, and Copolymer C] Next, copolymers A, B, and C were produced according to Production Examples 1 to 3 described below.

[0127] <Production Example 1: Production of Copolymer A> Into a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a nitrogen inlet tube, 44.67 g (185.8 mmol) of n-dodecyl acrylate, 3.78 g (19.3 mmol) of a monomer having phosphoric acid, and 61 mL of 2-propanol as a solvent were placed. Next, the atmosphere in the reaction vessel was replaced with nitrogen, and 0.2 g (1.2 mmol) of 2,2'-azodiisobutyronitrile was added as an initiator. The temperature was then slowly raised with stirring, and the reaction was carried out at a temperature of 75 to 85°C for 4 hours. After the reaction was completed, 48.45 g of mineral oil was added, and the unreacted monomer was distilled off under reduced pressure to obtain copolymer A.

[0128] Copolymer A corresponds to copolymer (X). Copolymer A is a copolymer represented by the general formula (a-1) where R a1 is a hydrogen atom, and R a2 is a linear alkyl group having 12 carbon atoms. b1 is a hydrogen atom, and R b2 is a linear alkylene group having 2 carbon atoms, m1 is 1, n is 1, and two R b3 is a hydrogen atom. The structure of Copolymer A is shown below: The obtained Copolymer A had (Mw)=20,000 and (Mw / Mn)=2.01. [ka] l and m indicate the number of repetitions.

[0129] <Production Example 2: Production of Copolymer B> Into a reaction vessel equipped with a stirrer, a heating / cooling device, a thermometer, and a nitrogen inlet tube, 44.67 g (185.8 mmol) of n-dodecyl acrylate, 3.78 g (26.4 mmol) of an amine-containing monomer, and 61 mL of 2-propanol as a solvent were placed. Next, the atmosphere in the reaction vessel was replaced with nitrogen, and 0.2 g (1.2 mmol) of 2,2'-azodiisobutyronitrile was added as an initiator. The temperature was then slowly raised with stirring, and the reaction was carried out at a temperature of 75 to 85°C for 4 hours. After the reaction was completed, 48.45 g of mineral oil was added, and the unreacted monomer was distilled off under reduced pressure to obtain copolymer B.

[0130] Copolymer B corresponds to copolymer (Y). Copolymer B is a copolymer represented by the general formula (a-1) where R a1 is a hydrogen atom, and R a2 is a linear alkyl group having 12 carbon atoms. c11 is a hydrogen atom, and R c12 is a linear alkylene group having 2 carbon atoms, m2 is 1, and R c13 and R c14 contains a structural unit (c1) derived from an amine-containing monomer (C1), which is an alkyl group having one carbon atom. The structure of Copolymer B is shown below: The obtained Copolymer B had (Mw)=5,000 and (Mw / Mn)=1.26. [ka] l and m indicate the number of repetitions.

[0131] <Production Example 3: Production of Copolymer C> Copolymer C was obtained by mixing 96.9 g of copolymer B with 12.85 g (26.1 mmol) of an acidic phosphate ester (number of carbon atoms: 18).

[0132] Copolymer C corresponds to copolymer (Y). Copolymer C is also a copolymer represented by the general formula (a-1) where R a1 is a hydrogen atom, and R a2 is a linear alkyl group having 12 carbon atoms. c11 is a hydrogen atom, and R c12 is a linear alkylene group having 2 carbon atoms, m2 is 1, and R c13 and R c14 contains a structural unit (c1) derived from an amine-containing monomer (C1), which is an alkyl group having one carbon atom. Also included is an acidic phosphate ester having 18 carbon atoms. The structure of Copolymer C is shown below: The obtained Copolymer C had (Mw)=4,900 and (Mw / Mn)=1.18. [ka] l and m indicate the number of repetitions.

[0133] [Examples 1 to 9, Comparative Examples 1 to 11] The lubricating oil base oil, other additives, and each lubricating oil additive composition produced in Production Examples 1 to 3 were blended and thoroughly mixed in the proportions shown in Tables 1 and 2 to prepare the lubricating oil compositions of Examples 1 to 9 and Comparative Examples 1 to 11, respectively. In Example 7, the same lubricating oil composition as in Example 6 was used, and the kinematic viscosity was measured by increasing the temperature from 40°C to 100°C and then decreasing the temperature from 100°C to 40°C, which was repeated twice. In Example 8, the kinematic viscosity was measured by repeating the temperature step three times in the same manner as in Example 7.

[0134] <Lubricant base oil> ·Mineral oil (40℃ kinematic viscosity: 31mm 2 / s, 100℃ kinematic viscosity: 5.38mm 2 / s, Viscosity Index: 107, API Classification: Group III)

[0135] <Other additives> Antioxidant: Phenolic antioxidant

[0136] The results are shown in Tables 1 and 2. The blending amounts of the lubricating oil additive compositions in Tables 1 and 2 include the blending amount of the diluent (50% by mass diluted with mineral oil).

[0137] [Table 1]

[0138] [Table 2]

[0139] As shown in Tables 1 to 2, it was found that the lubricating oil compositions of Examples 1 to 6 and 9 had higher viscosity indexes than the lubricating oil compositions of Comparative Examples 1 to 11. Therefore, from the results shown in Tables 1 and 2, it was found that the lubricating oil additive composition containing copolymer A and at least one of copolymer B and copolymer C has the effect of improving the viscosity index. Furthermore, the lubricating oil compositions of Examples 7 and 8 showed almost no difference in 40°C kinematic viscosity, 100°C kinematic viscosity, or viscosity index compared to the lubricating oil composition of Example 6. This demonstrates that the viscosity properties are maintained even when viscosity measurements are repeated.

[0140] [Confirmation of polymer complex formation] Next, for the lubricating oil composition of Example 3, the temperature was increased in the order of 40°C, 60°C, 80°C, and 100°C. 31 P-NMR was measured. After that, the temperature was lowered in the order of 100°C, 80°C, 60°C, and 40°C. 31P-NMR was measured. Figure 1 shows the results at each temperature when the temperature is increased in the order of 40℃, 60℃, 80℃, and 100℃. 31 The P-NMR spectrum is shown in Figure 2. After the measurement in Figure 1, the temperature was lowered in the order of 100°C, 80°C, 60°C, and 40°C. 31 The P-NMR spectrum is shown. In addition, 31 The P-NMR measurement conditions were as follows: No measurement solvent was used to ignore the interaction between the sample and the solvent. - 31 P-NMR measurement conditions: Equipment: Manufactured by JEOL Ltd. Frequency: 160MHz

[0141] In Figure 1, at 40°C, only the peak (A) derived from the phosphate group was observed. Next, at 60°C, a peak began to appear at position (B), which was shifted 1-2 ppm higher than the peak derived from the phosphate group. At 100°C, a peak derived from the phosphate-amine clearly appeared at position B, confirming that an ionic bond between the phosphate and amine had formed, resulting in the formation of a polymer complex. Furthermore, Figure 2 shows that a polymer complex having an ionic bond between phosphoric acid and amine was formed at 100°C, but the peaks derived from the phosphoric acid and amine disappeared as the temperature was lowered in increments of 20°C. This indicates that the polymer complex having an ionic bond between phosphoric acid and amine dissociated as the temperature decreased. Furthermore, the same procedure was repeated three times and the same results were obtained.

[0142] [Evaluation of oxidation stability] In the lubricating oil compositions of Examples 3 and 9, the phosphate group-containing polymer, the amine-containing polymer, and the polymer composite were each evaluated for oxidation stability by measuring the acid value before and after a hot tube test. First, the acid value of the lubricating oil composition before the hot tube test was measured by potentiometric titration in accordance with JIS K2501:2003-7. Next, a hot tube test was carried out in accordance with JPI-5S-55-99. Specifically, the lubricating oil compositions of Examples 3 and 9 were flowed into a glass tube having an inner diameter of 2 mm at a rate of 0.3 mL / hour and air at a rate of 10 mL / minute for 16 hours while the temperature of the glass tube was maintained at 200°C. After the hot tube test, the lubricating oil composition was recovered and its acid number was measured by potentiometric titration in accordance with JIS K2501:2003, paragraph 7. The lower the acid number, the better the oxidation stability.

[0143] [Table 3]

[0144] Since amine groups are easily oxidized, the acid values ​​of copolymer B and the polymer composite after the hot tube test were much higher than the acid values ​​before the test in the lubricating oil composition of Example 3. In contrast, the lubricating oil composition of Example 9 used copolymer C in which the amine groups were protected with phosphoric acid, and further contained an antioxidant, which prevented the increase in acid value and improved oxidation stability.

Claims

1. a copolymer (X) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing a phosphate group; and a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in the side chain and containing an amine group.

2. The lubricating oil additive composition according to claim 1, wherein at least one of the copolymer (X) and the copolymer (Y) contains a structural unit (a1) derived from a monomer (A1) represented by the following general formula (a-1) as a monomer having an alkyl group having 1 to 40 carbon atoms: 【Chemical 1】 [In the general formula (a-1), R ａ１ represents a hydrogen atom or a methyl group. ａ２ represents an alkyl group having 1 to 40 carbon atoms.

3. The lubricating oil additive composition according to claim 1 or 2, wherein the copolymer (X) comprises a structural unit (b1) derived from a phosphorus-containing monomer (B1) represented by the following general formula (b-1): 【Chemistry 2】 [In the general formula (b-1), R ｂ１ is a hydrogen atom or a methyl group. ｂ２ represents a linear or branched alkylene group having 2 to 4 carbon atoms. m1 represents an integer of 1 to 6. When m1 is an integer of 2 or more, a plurality of R ｂ２ may be the same or different. n represents an integer of 1 or 2. When n=1, a plurality of R ｂ３ At least one of R represents a hydrogen atom, and the remaining R ｂ３ represents a hydrogen atom, a methyl group, or an ethyl group. When n=2, R ｂ３ is a hydrogen atom.]

4. The lubricating oil additive composition according to any one of claims 1 to 3, wherein the copolymer (Y) comprises a structural unit (c1) derived from an amine-containing monomer (C1) represented by the following general formula (c-1): 【Chemistry 3】 [In the general formula (c-1), R ｃ１１ is a hydrogen atom or a methyl group. ｃ１２ represents a linear or branched alkylene group having 2 to 4 carbon atoms. m2 represents an integer of 1 to 10. When m2 is an integer of 2 or more, a plurality of R ｃ１２ may be the same or different. ｃ１３ and R ｃ１４ 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 claims 1 to 4, wherein the blending ratio [(X) / (Y)] of the copolymer (X) to the copolymer (Y) is 1 / 7 to 7 / 1 in mass ratio.

6. The lubricating oil additive composition according to any one of claims 1 to 5, wherein the content of phosphorus atoms (P) is 0.1 mass% or more based on the total amount of the copolymer (X).

7. The lubricating oil additive composition according to any one of claims 1 to 6, wherein the content of nitrogen atoms (N) is 0.1 mass% or more based on the total amount of the copolymer (Y).

8. 8. The lubricating oil additive composition according to claim 1, wherein the ratio of the content of phosphorus atoms (P) to the content of nitrogen atoms (N) [(P) / (N)] is, in mass ratio, 1 / 7 to 7 / 1.

9. The lubricating oil additive composition according to any one of claims 1 to 8, which is used as a viscosity index improver.

10. A lubricating oil composition comprising the lubricating oil additive composition according to any one of claims 1 to 9 and a lubricating base oil.

11. 11. The lubricating oil composition of claim 10, further comprising one or more additives selected from the group consisting of metal-based detergents, antiwear agents, ashless dispersants, extreme pressure agents, antioxidants, pour point depressants, antifoam agents, surfactants or demulsifiers, friction modifiers, oiliness improvers, rust inhibitors, and metal deactivators.

12. a copolymer (X) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing a phosphate group; a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing an amine group;

13. a lubricating base oil; a copolymer (X) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing a phosphate group; a copolymer (Y) having an alkyl group having 1 to 40 carbon atoms in its side chain and containing an amine group;

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