Antifoaming agent, lubricating oil composition containing antifoaming agent, and machine using the lubricating oil composition

Abstract

To provide an antifoaming agent that exhibits excellent antifoaming properties even in a high-temperature environment. -Si[OSi(R)3] n [R’] 3-n An antifoaming agent which is a polymer having at least a polymerizable monomer (1) having a functional group represented by (n is an integer in the range of 1 to 3. Each R is independently an alkyl group having 1 to 3 carbon atoms. Each R’ is independently an alkyl group having 1 to 3 carbon atoms) and having one polymerizable unsaturated group, and a polymerizable monomer (2) having two or more polymerizable unsaturated groups as polymerization components.

Description

Technical Field

[0001] The present invention relates to an antifoaming agent, a lubricating oil composition containing the antifoaming agent, and a machine using the lubricating oil composition.

Background Art

[0002] In recent years, reduction of carbon dioxide emissions has become an important theme in the industrial world. Among them, the carbon dioxide emissions of transportation equipment including automobiles account for nearly 20% of the total. As one of the countermeasures to reduce this, switching from gasoline vehicles to electric vehicles (EVs) has been adopted as the policy of each country.

[0003] The most important issue in EVs is improvement of fuel efficiency. For this purpose, studies such as downsizing of the vehicle body and high-efficiency of the drive system are being advanced at a rapid pace. One of the issues of high-efficiency of the drive system is foaming of the lubricating oil. The lubricating oil is being made lower in viscosity to reduce frictional resistance, but this lower viscosity makes it easier to foam.

[0004] When high-load operation and high-speed driving are continuously performed, foaming increases in the low-viscosity lubricating oil, and the lubricating performance and cooling efficiency decrease due to foaming; wear and seizure occur due to breakage of the oil film at the friction part; problems such as acceleration of deterioration of the lubricating oil due to an increase in the oil temperature may occur.

[0005] For this reason, a lubricating oil having high antifoaming properties is required so that foaming can be suppressed from the initial stage of operation to a long term, and the lubricating oil contains an antifoaming agent for preventing foaming. As the antifoaming agent, polysiloxane-based antifoaming agents are known, and various polysiloxane-based antifoaming agents have been proposed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] Conventional polysiloxane-based defoaming agents have the problem that their defoaming properties decrease significantly as the temperature rises. For example, there has been a problem in that sufficient defoaming properties cannot be obtained in automotive applications where defoaming properties at high temperatures are required.

[0008] The problem to be solved by the present invention is to provide a defoaming agent that exhibits excellent defoaming properties even in a high-temperature environment. Another problem to be solved by the present invention is to provide a lubricating oil composition that can exhibit excellent lubricating performance even in a high-temperature environment. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above problems and have found that a polymer containing, as polymerization components, a polymerizable monomer having a specific silicone functional group and one polymerizable unsaturated group, and a polymerizable monomer having two or more polymerizable unsaturated groups is an antifoaming agent that exhibits excellent antifoaming properties even in high-temperature environments, thereby completing the present invention.

[0010] That is, the present invention relates to the following defoaming agents, etc. 1.-Si[OSi(R)3] n [R'] 3-n (n is an integer ranging from 1 to 3; each R is independently an alkyl group having 1 to 3 carbon atoms; each R' is independently an alkyl group having 1 to 3 carbon atoms), and containing a polymer having as polymerization components at least a polymerizable monomer (1) having one polymerizable unsaturated group and a polymerizable monomer (2) having two or more polymerizable unsaturated groups. 2. The defoaming agent according to 1, wherein the polymerizable monomer (1) is a compound represented by the following general formula (1-1): [ka] (In the general formula (1-1), Each R is independently an alkyl group having 1 to 3 carbon atoms. Each R' is independently an alkyl group having 1 to 3 carbon atoms. L 11 is a divalent organic group or a single bond. n is an integer ranging from 1 to 3. P is a polymerizable group represented by general formula (P-1), a polymerizable group represented by general formula (P-2), or a polymerizable group represented by general formula (P-3). In the general formula (P-1), the general formula (P-2) and the general formula (P-3), R 11 is a hydrogen atom or a methyl group. R 12 is a hydrogen atom or an organic group. R 13 is a hydrogen atom or a methyl group. * is L 11 ) 3. The defoaming agent according to 1 or 2, wherein the content of the polymerizable monomer (1) in the polymerization components is in the range of 10% by mass or more. 4. The defoaming agent according to any one of 1 to 3, wherein the polymerizable monomer (2) is a compound represented by the following general formula (2-1): [ka] (In the general formula (2-1), R 21 is a hydrogen atom or a methyl group. x is an integer equal to or greater than 2, L 21 is an x-valent organic group. 5. The defoaming agent according to any one of 1 to 4, wherein the content of the polymerizable monomer (2) in the polymerization components is in the range of 1 to 75 mass %. 6. The defoaming agent according to any one of 1 to 5, wherein the polymerization component comprises a polymerizable monomer (3) having one or more selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an aromatic group having 6 to 18 carbon atoms, a group containing a polyoxyalkylene chain, and a group containing a polyester chain. 7. The defoaming agent according to 6, wherein the polymerizable monomer (3) is at least one selected from the group consisting of a compound represented by the following general formula (3-1), a compound represented by the following general formula (3-2), a compound represented by the following general formula (3-3), a compound represented by the following general formula (3-4), and a compound represented by the following general formula (3-5).

Chemical formula

Advantages of the Invention

[0011] According to the present invention, a defoaming agent showing excellent defoaming properties even under a high-temperature environment can be provided. According to the present invention, a lubricating oil composition capable of showing excellent lubricating performance even under a high-temperature environment can be provided.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, an embodiment of the present invention will be described. The present invention is not limited to the following embodiments and can be implemented with appropriate modifications without impairing the effects of the present invention. In the present specification, “(meth)acrylate” means one or both of acrylate and methacrylate.

[0013] [Defoaming Agent] The defoaming agent of the present invention is -Si[OSi(R)3] n [R’] 3-n(n is an integer from 1 to 3. Each R is independently an alkyl group having 1 to 3 carbon atoms. Each R’ is independently an alkyl group having 1 to 3 carbon atoms), and contains a polymer having as at least polymerization components a polymerizable monomer (1) having a functional group represented thereby and having one polymerizable unsaturated group, and a polymerizable monomer (2) having two or more polymerizable unsaturated groups. Here, the “polymerization component” means a component constituting the polymer, and does not include a solvent, a polymerization initiator, etc. that do not constitute the polymer.

[0014] In the present invention, the “polymerizable monomer” means a compound having a polymerizable unsaturated group. Examples of the polymerizable unsaturated groups of the polymerizable monomer (1) and the polymerizable monomer (2) include (meth)acryloyl group, (meth)acryloyloxy group, (meth)acrylamide group, vinyl ether group, allyl group, styryl group, (meth)acrylamino group, maleimide group, etc.

[0015] The polymer having as at least polymerization components the polymerizable monomer (1) and the polymerizable monomer (2) which are the antifoaming agents of the present invention may be referred to as the “polymer of the present invention”. Hereinafter, each component constituting the polymer of the present invention will be described below.

[0016] The functional group represented by -Si[OSi(R)3] n [R’] 3-n is preferably a functional group represented by -Si[OSi(R)3]3, and more preferably -Si[OSi(CH3)3]3.

[0017] The polymerizable monomer (1) is preferably a compound represented by the following general formula (1-1).

[0018] TIFF0007715302000004.tif100130 (In the above general formula (1-1), each R is independently an alkyl group having 1 to 3 carbon atoms each R’ is independently an alkyl group having 1 to 3 carbon atoms. L 11is a divalent organic group or a single bond. n is an integer in the range of 1 to 3. P is a polymerizable group represented by the general formula (P-1), a polymerizable group represented by the general formula (P-2), or a polymerizable group represented by the general formula (P-3). In the general formula (P-1), the general formula (P-2), and the general formula (P-3), R 11 is a hydrogen atom or a methyl group. R 12 is a hydrogen atom or an organic group. R 13 is a hydrogen atom or a methyl group. * is a bond that binds to L 11 (.)

[0019] L 11 The "single bond" of L means the case where O and Si are directly bonded. L 11 The divalent organic group of L is preferably an alkylene group having 1 to 50 carbon atoms or an alkyleneoxy group having 1 to 50 carbon atoms.

[0020] L 11 Examples of the alkylene group having 1 to 5 carbon atoms of L include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-nonylene group, an n-decylene group, an n-dodecylene group, an isopropylene group, a 2-methylpropylene group, a 2-methylhexylene group, a tetramethylethylene group, and the like.

[0021] L 11 The alkylene group having 1 to 50 carbon atoms of L is preferably an alkylene group having 1 to 15 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms, and still more preferably a methylene group, an ethylene group, an n-propylene group, or an isopropylene group.

[0022] L 11 The alkyleneoxy group having 1 to 50 carbon atoms of L is, for example, a group in which one or more -CH2- in the alkylene group are replaced by -O-. L 11 The alkyleneoxy group having 1 to 50 carbon atoms is preferably an alkyleneoxy group having 1 to 15 carbon atoms, more preferably an alkyleneoxy group having 1 to 8 carbon atoms, and even more preferably a methyleneoxy group, an ethyleneoxy group, a propyleneoxy group, an oxytrimethylene group, a butyleneoxy group, an oxytetramethylene group, a pentyleneoxy group, a heptyleneoxy group, or an octyleneoxy group.

[0023] L 11 When the divalent organic group is an alkylene group having 1 to 50 carbon atoms or an alkyleneoxy group having 1 to 50 carbon atoms, some of the -CH2- groups in these divalent organic groups may be replaced by a carbonyl group (-C(=O)-), a phenylene group, an amide bond, or a urethane bond (-NHC(=O)-).

[0024] L 11 When the divalent organic group is an alkylene group having 1 to 50 carbon atoms or an alkyleneoxy group having 1 to 50 carbon atoms, the carbon atoms of these groups may further be substituted with a substituent such as a hydroxyl group.

[0025] R 12 The organic group may be, for example, an alkyl group having 1 to 18 carbon atoms. R 12 Examples of the alkylene group having 1 to 18 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-dodecyl group, an isopropyl group, a 2-methylpropyl group, a 2-methylhexyl group, and a tetramethylethyl group.

[0026] n is preferably 2 or 3, and more preferably 3. The compound represented by the general formula (1-1) is preferably a compound represented by the following general formula (1-2) (n=3) or a compound represented by the following general formula (1-3) (n=2), and more preferably a compound represented by the following general formula (1-2).

[0027] [Chemical formula] (In the general formulas (1-2) and (1-3), P, R', R 11 , and L 11 are the same as P, R', R 11 and L 11 in the general formula (1-1).)

[0028] The polymerizable monomer (1) as a polymerization component may be used alone or may be two or more polymerizable monomers (1) having different structures from each other.

[0029] The polymerizable monomer (1) can be produced by a known method, and a commercially available product may be used. As a commercially available product of the polymerizable monomer (1), for example, 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane is commercially available.

[0030] As the polymerizable monomer (1), in addition to the above 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane, for example, the following compounds can also be used.

[0031] [Chemical formula]

[0032] In the polymer of the present invention, the lower limit of the content ratio of the polymerizable monomer (1) is, for example, 10% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, or 35% by mass or more with respect to the total amount of the polymerization components of the polymer. The upper limit of the content ratio of the polymerizable monomer (1) is not particularly limited, but is, for example, 99% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass or less with respect to the total amount of the polymerization components of the polymer. The combination of the upper and lower limits of the content of the polymerizable monomer (1) is, for example, in the range of 10% by mass to 99% by mass of the total amount of the polymerizable components of the polymer, and preferably in the range of 25% by mass to 80% by mass of the total amount of the polymerizable components of the polymer. The content of the polymerizable monomer (1) can be adjusted by the raw material charge ratio of the polymerizable monomer (1) when producing the polymer of the present invention.

[0033] The polymerizable monomer (2) is a polymerizable monomer having two or more polymerizable unsaturated groups, and may have two or more of one type of polymerizable unsaturated group, or may have two or more of two or more types of polymerizable unsaturated groups. The polymerizable monomer (2) is preferably a polymerizable monomer having two or more (meth)acryloyl groups or a polymerizable monomer having two or more (meth)acryloyloxy groups.

[0034] The polymerizable monomer (2) is preferably a compound represented by the following general formula (2-1).

[0035] [ka] (In the general formula (2-1), R 21 is a hydrogen atom or a methyl group. n2 is an integer equal to or greater than 2, L 21 is an n2-valent organic group.

[0036] n2 may be any integer of 2 or greater, for example, an integer in the range of 2 to 12, preferably an integer in the range of 2 to 8, more preferably an integer in the range of 2 to 6, and even more preferably an integer in the range of 2 to 4.

[0037] L 21 The n2-valent organic group is an organic group having a valence corresponding to the value of n2. For example, when n2 is 2, it is a divalent organic group, and when n2 is 6, it is a hexavalent organic group.

[0038] L 21is preferably an alkylene group having 1 to 50 carbon atoms or an alkyleneoxy group having 1 to 50 carbon atoms, and is an organic group in which a hydrogen atom bonded to a carbon atom of the alkylene group and the alkyleneoxy group is replaced with a bond so as to have a valence corresponding to the value of n2. Therefore, when L 21 is a divalent organic group, L 21 is preferably an alkylene group having 1 to 50 carbon atoms or an alkyleneoxy group having 1 to 50 carbon atoms.

[0039] L 21 Examples of the alkylene group having 1 to 50 carbon atoms of L include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-pentylene group, an n-hexylene group, an n-heptylene group, an n-octylene group, an n-nonylene group, an n-decylene group, an n-dodecylene group, an isopropylene group, a 2-methylpropylene group, a 2-methylhexylene group, a tetramethylethylene group, and the like.

[0040] L 21 The alkylene group having 1 to 50 carbon atoms of L is preferably an alkylene group having 1 to 15 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms, and still more preferably a methylene group, an ethylene group, an n-propylene group or an isopropylene group.

[0041] L 21 The alkyleneoxy group having 1 to 50 carbon atoms of L is, for example, a group in which one or more —CH2— in the alkylene group are replaced with —O—. L 21 The alkyleneoxy group having 1 to 50 carbon atoms of L is preferably an alkyleneoxy group having 1 to 15 carbon atoms, more preferably an alkyleneoxy group having 1 to 8 carbon atoms, and still more preferably a methyleneoxy group, an ethyleneoxy group, a propyleneoxy group, an oxytrimethylene group, a butyleneoxy group, an oxytetramethylene group, a pentyleneoxy group, a heptyleneoxy group or an octyleneoxy group.

[0042] L 21When the divalent organic group is an alkylene group having 1 to 50 carbon atoms or an alkyleneoxy group having 1 to 50 carbon atoms, a part of -CH2- in these divalent organic groups may be replaced by a carbonyl group (-C(=O)-), a phenylene group, a sulfide bond (-S-), an amide bond or a urethane bond.

[0043] L 21 When the divalent organic group is an alkylene group having 1 to 50 carbon atoms or an alkyleneoxy group having 1 to 50 carbon atoms, a substituent such as a hydroxyl group may be further substituted on the carbon atoms of these groups.

[0044] Specific examples of the polymerizable monomer (2) include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 2-hydroxy-3-methacryloylpropyl acrylate, 2-hydroxy-1,3-dimethacryloxypropane, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris-(2-acryloxyethyl) isocyanurate, bis-(2-acryloxyethyl) isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polypentaerythritol poly(meth)acrylate, and the like.

[0045] The polymerizable monomer (2) which is a polymerizable component may be a single type alone, or may be two or more types of polymerizable monomers (2) having different structures from each other.

[0046] The polymerizable monomer (2) can be produced by a known method, and commercially available products may also be used.

[0047] In the polymer of the present invention, the content ratio of the polymerizable monomer (2) is, for example, in the range of 0.1 to 900 parts by mass with respect to 100 parts by mass of the polymerizable monomer (1), preferably in the range of 1 to 500 parts by mass with respect to 100 parts by mass of the polymerizable monomer (1), more preferably in the range of 3 to 300 parts by mass with respect to 100 parts by mass of the polymerizable monomer (1). Even more preferably, it is in the range of 5 to 200 parts by mass with respect to 100 parts by mass of the polymerizable monomer (1). The content ratio of the polymerizable monomer (2) can be adjusted by the raw material charging ratio of the polymerizable monomer (2) when producing the polymer of the present invention.

[0048] In the polymer of the present invention, the content ratio of the polymerizable monomer (2) is, for example, in the range of 0.1 to 90% by mass with respect to the total amount of the polymerizable components of the polymer, preferably in the range of 1 to 75% by mass, more preferably in the range of 3 to 60% by mass, and even more preferably in the range of 5 to 50% by mass.

[0049] The polymerizable components of the polymer of the present invention preferably further include, in addition to the polymerizable monomer (1) and the polymerizable monomer (2), a polymerizable monomer (3) having one or more selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an aromatic group having 6 to 18 carbon atoms, a group containing a polyoxyalkylene chain, and a group containing a polyester chain as a further polymerizable component. By further including the polymerizable monomer (3) as a polymerizable component, for example, when the antifoaming agent of the present invention is added to a lubricating oil composition, high compatibility of the antifoaming agent with the lubricating oil base oil can be ensured.

[0050] The alkyl group having 1 to 18 carbon atoms that the polymerizable monomer (3) has may be any of a linear alkyl group, a branched alkyl group, and a cyclic alkyl group. Specific examples include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an n-hexyl group, a cyclohexyl group, an n-octyl group, a hexadecyl group, and the like. The alkyl group having 1 to 18 carbon atoms that the polymerizable monomer (3) has is preferably an alkyl group having 1 to 6 carbon atoms.

[0051] Examples of the aromatic group having 6 to 18 carbon atoms that the polymerizable monomer (3) has include a phenyl group, a naphthyl group, an anthracen-1-yl group, a phenanthren-1-yl group, and the like.

[0052] The group containing a (poly)oxyalkylene chain that the polymerizable monomer (3) has is a monovalent group containing a repeating portion of oxyalkylene or a divalent linking group containing a repeating portion of oxyalkylene.

[0053] The group containing a polyester chain that the polymerizable monomer (3) has is a monovalent group containing a repeating portion of an ester bond or a divalent linking group containing a repeating portion of an ester bond.

[0054] The alkyl group having 1 to 18 carbon atoms that the polymerizable monomer (3) has may further have a substituent. Examples of the substituent include a hydroxyl group, an aryl group, and the like. The aromatic group having 6 to 18 carbon atoms that the polymerizable monomer (3) has may further have a substituent. Examples of the substituent include a hydroxyl group, an alkyl group, and the like.

[0055] Examples of the polymerizable monomer (3) having an alkyl group with 1 to 18 carbon atoms and a polymerizable unsaturated group being a (meth)acryloyl group include alkyl esters of (meth)acrylic acid with 1 to 18 carbon atoms such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate; and bridged cyclic alkyl esters of (meth)acrylic acid with 1 to 18 carbon atoms such as dicyclopentyloxyethyl (meth)acrylate, isobornyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dimethyladamantyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, etc. In the present application, “(meth)acrylate” means both methacrylate and acrylate.

[0056] Examples of the polymerizable monomer (3) having a phenylalkyl group with 7 to 18 carbon atoms or a phenoxyalkyl group with 7 to 18 carbon atoms and a polymerizable unsaturated group being a (meth)acryloyl group include benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, etc.

[0057] Examples of the polymerizable monomer (3) having an alkyl group with 1 to 18 carbon atoms and a polymerizable unsaturated group being a vinyl ether group include alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, n-dodecyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether; cycloalkyl vinyl ethers and the like.

[0058] Examples of the polymerizable monomer (3) having an aromatic group with 6 to 18 carbon atoms include styrene, α-methylstyrene, p-methylstyrene, p-methoxystyrene and the like.

[0059] Examples of the polymerizable monomer (3) having an alkyl group with 1 to 18 carbon atoms and a polymerizable unsaturated group being a (meth)acryloylamino group include N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, diacetoneacrylamide, acryloylmorpholine and the like.

[0060] Examples of the polymerizable monomer (B) having an alkyl group with 1 to 18 carbon atoms and a polymerizable unsaturated group being a maleimide group include methyl maleimide, ethyl maleimide, propyl maleimide, butyl maleimide, hexyl maleimide, octyl maleimide, dodecyl maleimide, stearyl maleimide, cyclohexyl maleimide and the like.

[0061] Examples of the polymerizable monomer (3) having a group containing a polyoxyalkylene chain and having a polymerizable unsaturated group being a (meth)acryloyl group include polypropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polytrimethylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, poly(ethylene glycol·propylene glycol) mono(meth)acrylate, polyethylene glycol·polypropylene glycol mono(meth)acrylate, poly(ethylene glycol·tetramethylene glycol) mono(meth)acrylate, polyethylene glycol·polytetramethylene glycol mono(meth)acrylate, poly(propylene glycol·tetramethylene glycol) mono(meth)acrylate, polypropylene glycol·polytetramethylene glycol mono(meth)acrylate, poly(propylene glycol·1,2-butylene glycol) mono(meth)acrylate, polypropylene glycol·poly1,2-butylene glycol mono(meth)acrylate, poly(ethylene glycol·1,2-butylene glycol) mono(meth)acrylate, polyethylene glycol·poly1,2-butylene glycol mono(meth)acrylate, poly(tetraethylene glycol·1,2-butylene glycol) mono(meth)acrylate, polytetraethylene glycol·poly1,2-butylene glycol mono(meth)acrylate, poly1,2-butylene glycol mono(meth)acrylate, poly(ethylene glycol·trimethylene glycol) mono(meth)acrylate, polyethylene glycol·polytrimethylene glycol mono(meth)acrylate, poly(propylene glycol·trimethylene glycol) mono(meth)acrylate, polypropylene glycol·polytrimethylene glycol mono(meth)acrylate, poly(trimethylene glycol·tetramethylene glycol) mono(meth)acrylate, polytrimethylene glycol·polytetramethylene glycol mono(meth)acrylate, poly(1,2-butylene glycol·trimethylene glycol) mono(meth)acrylate, poly1,2-Butylene glycol·polytetramethylene glycol mono(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, poly(1,2-butylene glycol·tetramethylene glycol) mono(meth)acrylate, poly 1,2-butylene glycol·polytetramethylene glycol mono(meth)acrylate, and the like can be mentioned., In addition, the above "poly(ethylene glycol·propylene glycol)" means a random copolymer of ethylene glycol and propylene glycol, and "polyethylene glycol·polypropylene glycol" means a block copolymer of ethylene glycol and propylene glycol.,

[0062] The polymerizable monomer (3) is preferably at least one selected from the group consisting of a compound represented by the following general formula (3-1), a compound represented by the following general formula (3-2), a compound represented by the following general formula (3-3), and a compound represented by the following general formula (3-4).

[0063] [Chemical formula] (In the general formulas (3-1), (3-2), (3-3), (3-4), and (3-5), R 31 is a hydrogen atom or a methyl group, R 32 is an alkyl group having 1 to 18 carbon atoms, R 33 is a hydrogen atom or a methyl group, R 34 is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, R 35 is a hydrogen atom or a methyl group, R 36 is an alkyl group having 1 to 18 carbon atoms, an alkyl group having an ether bond having 1 to 18 carbon atoms, or a hydrogen atom, R 37 is a hydrogen atom or a methyl group, R 38 is an alkyl group having 1 to 18 carbon atoms, an alkyl group having 1 to 18 carbon atoms and an ether bond, or a hydrogen atom, L 3 is a divalent organic group or a single bond, R 39 is a hydrogen atom or a methyl group, R 40 are each independently an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, n is an integer ranging from 1 to 4, m is the number of repetitions, the number average value of m is in the range of 1 to 200, p is an integer ranging from 1 to 10, q is the number of repetitions, the number average value of q is in the range of 1 to 100, and l is an integer ranging from 0 to 5.

[0064] In the formula (3-2), the m n's in the parentheses may be the same or different. In the formula (3-3), the q p's in the parentheses may be the same or different. In the formula (3-4), the q p's in the parentheses may be the same or different.

[0065] R 32 , R 34 , R 36 and R 38 The alkyl group having 1 to 18 carbon atoms may further have a substituent, and examples of the substituent include a hydroxyl group and an aryl group. R 36 and R 38 The alkyl group having 1 to 18 carbon atoms and an ether bond may further have a substituent, and examples of the substituent include a hydroxyl group and an aryl group. R 30 The alkyl group having 1 to 6 carbon atoms may further have a substituent, and examples of the substituent include a hydroxyl group and an aryl group. R 40 The alkoxy group having 1 to 6 carbon atoms may further have a substituent, and examples of the substituent include a hydroxyl group and an aryl group.

[0066] The divalent organic group L in the formulas (3-3) and (3-4) 3 is the same as the divalent organic group L 11 . Examples thereof include the same as the divalent organic group L

[0067] In the general formula (3-2), m represents the number of repetitions, and for example, m may be an integer of 1 or more. The number average of m is, for example, in the range of 1 to 200, preferably in the range of 1 to 100, and more preferably in the range of 1 to 50. The number average value of m can be confirmed by measuring the number average molecular weight of the polymerizable monomer (3) by the method described in the examples.

[0068] In the general formulas (3-3) and (3-4), q represents the number of repetitions, and for example, q may be an integer of 1 or more. The number average of q is, for example, in the range of 1 to 100, preferably in the range of 1 to 80, and more preferably in the range of 1 to 50.

[0069] The polymerizable monomer (3) preferably contains one or more selected from the group consisting of the compound represented by the formula (3-2), the compound represented by the formula (3-3), and the compound represented by the formula (3-4). When the polymerizable monomer (3) contains one or more selected from the group consisting of the compound represented by the formula (3-2), the compound represented by the formula (3-3), and the compound represented by the formula (3-4), the total amount of the compound represented by the formula (3-2), the compound represented by the formula (3-3), and the formula (3-4) is preferably 50% by mass or more based on the total amount of the polymerizable monomer (3).

[0070] The polymerizable monomer (3) as the polymerization component may be a single type or two or more types of polymerizable monomers (3) having different structures from each other.

[0071] The polymerizable monomer (3) can be produced by a known method. Alternatively, commercially available products may be used as the polymerizable monomer (3). For example, as commercially available products of the polymerizable monomer (3) having a group containing a polyoxyalkylene chain and a polymerizable unsaturated group being a (meth)acryloyl group, "NK Ester M-20G", "NK Ester M-40G", "NK Ester M-90G", "NK Ester M-230G", "NK Ester AM-90G", "NK Ester AMP-10G", "NK Ester AMP-20G", "NK Ester AMP-60G" manufactured by Shin-Nakamura Chemical Co., Ltd.; "Blemmer PE-90", "Blemmer PE-200", "Blemmer PE-350", "Blemmer PME-100", "Blemmer PME-200", "Blemmer PME-400", "Blemmer PME-4000", "Blemmer PP-1000", "Blemmer PP-500", "Blemmer PP-800", "Blemmer 70PEP-350B", "Blemmer 55PET-800", "Blemmer 50POEP-800B", "Blemmer 10PPB-500B", "Blemmer NKH-5050", "Blemmer AP-400", "Blemmer AE-350" manufactured by NOF Corporation; Placcel F series manufactured by Daicel Corporation; Biscote series manufactured by Osaka Organic Chemical Industry Co., Ltd., etc. can be mentioned.

[0072] When the polymerizable monomer (3) is included as a polymerization component, the content ratio of the polymerizable monomer (3) is, for example, in the range of 0 to 200 parts by mass with respect to 100 parts by mass of the polymerizable monomer (1), preferably in the range of 20 to 200 parts by mass with respect to 100 parts by mass of the polymerizable monomer (1), more preferably in the range of 40 to 150 parts by mass with respect to 100 parts by mass of the polymerizable monomer (1), and still more preferably in the range of 70 to 120 parts by mass with respect to 100 parts by mass of the polymerizable monomer (1). The content ratio of the polymerizable monomer (3) can be adjusted by the raw material charging ratio of the polymerizable monomer (3) when producing the polymer of the present invention.

[0073] In the polymer of the present invention, the content ratio of the polymerizable monomer (3) is, for example, in the range of 0 to 90% by mass, preferably in the range of 1 to 80% by mass, more preferably in the range of 3 to 75% by mass, and still more preferably in the range of 5 to 70% by mass with respect to the total amount of the polymerization components of the polymer.

[0074] The polymer of the present invention may be a polymer having the polymerizable monomer (1), the polymerizable monomer (2) and an optional polymerizable monomer (3) as polymerization components, and may contain other polymerizable monomers other than the polymerizable monomer (1), the polymerizable monomer (2) and the optional polymerizable monomer (3) as polymerization components as long as the effects of the present invention are not impaired. The polymer of the present invention is preferably a polymer substantially composed of the polymerizable monomer (1), the polymerizable monomer (2) and an optional polymerizable monomer (3), and more preferably a copolymer composed only of the polymerizable monomer (1), the polymerizable monomer (2) and an optional polymerizable monomer (3). Here, "substantially composed of" means a case where the total content ratio of the polymerizable monomer (1), the polymerizable monomer (2) and an optional polymerizable monomer (3) in the polymerization components of the polymer of the present invention is 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more.

[0075] The polymerization form of the polymer of the present invention is not particularly limited. The polymer of the present invention may be a random polymer of the polymerizable monomer (1), the polymerizable monomer (2) and an optional polymerizable monomer (3). Further, the polymer of the present invention may be a block polymer having one or more polymer blocks of the polymerizable monomer (1), the polymerizable monomer (2) and an optional polymerizable monomer (3).

[0076] Preferably, the polymer of the present invention does not contain a fluorine atom.

[0077] The number average molecular weight (Mn) of the polymer of the present invention is preferably in the range of 1,000 to 50,000, more preferably in the range of 1,000 to 30,000, and still more preferably in the range of 1,500 to 10,000. The weight average molecular weight (Mw) of the polymer of the present invention is preferably in the range of 1,000 to 300,000, more preferably in the range of 1,500 to 250,000, still more preferably in the range of 2,000 to 200,000, and particularly preferably in the range of 3,000 to 150,000.

[0078] In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values converted to polystyrene based on gel permeation chromatography (GPC) measurement. The values of the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the polymer of the present invention are measured by the method described in the examples.

[0079] The defoaming agent of the present invention may contain the polymer of the present invention, and may also contain a defoaming agent other than the polymer of the present invention. Further, the defoaming agent of the present invention may be the polymer of the present invention.

[0080] [Method for producing polymer] The method for producing the polymer of the present invention is not particularly limited, and it can be produced by a known method. The polymer of the present invention can be produced by a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, etc. based on a polymerization mechanism such as a radical polymerization method, a cationic polymerization method, or an anionic polymerization method. For example, in the case of a radical polymerization method, a polymerizable monomer mixture is charged into an organic solvent, and a general-purpose radical polymerization initiator is added to produce the polymer of the present invention.

[0081] As the polymerization initiator, various ones can be used. For example, peroxides such as t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, and diacyl peroxide, azo compounds such as azobisisobutyronitrile, dimethyl azobisisobutyrate, and phenylazotriphenylmethane, and metal chelate compounds such as Mn(acac)3 can be mentioned. Optionally, a chain transfer agent such as lauryl mercaptan, 2-mercaptoethanol, ethyl thioglycolic acid, octyl thioglycolic acid, or a thiol compound having a coupling group such as γ-mercaptopropyltrimethoxysilane may be used as an additive such as a chain transfer agent.

[0082] Examples of the organic solvent include alcohols such as ethanol, isopropyl alcohol, n-butanol, iso-butanol, tert-butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, butyl lactate; monocarboxylic acid esters such as methyl 2-oxypropionate, ethyl 2-oxypropionate, propyl 2-oxypropionate, butyl 2-oxypropionate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, propyl 2-methoxypropionate, butyl 2-methoxypropionate; polar solvents such as dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone; ethers such as methyl cellosolve, cellosolve, butyl cellosolve, butyl carbitol, ethyl cellosolve acetate; propylene glycols and their esters such as propylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate; halogenated solvents such as 1,1,1-trichloroethane, chloroform; ethers such as tetrahydrofuran, dioxane; aromatics such as benzene, toluene, xylene; and fluorinated inert liquids such as perfluorooctane, perfluorotri-n-butylamine, etc. These solvents can be used alone or in combination of two or more.

[0083] The polymer of the present invention can also be produced by living polymerization such as living radical polymerization and living anionic polymerization.

[0084] Living radical polymerization is a process in which a dormant species with an active polymerization end protected by an atom or atomic group reversibly generates radicals and reacts with monomers to proceed with the growth reaction. Even when the first monomer is consumed, the growth end does not lose its activity and can react with a sequentially added second monomer to obtain a block polymer. Examples of such living radical polymerization include atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT), nitroxide-mediated radical polymerization (NMP), and radical polymerization using organic tellurium (TERP). Among these, there are no particular restrictions on which method to use, but ATRP is preferred due to its ease of control. ATRP is polymerized using an organic halide or a sulfonyl halide compound as a polymerization initiator and a metal complex composed of a transition metal compound and a ligand as a catalyst.

[0085] Specific examples of polymerization initiators that can be used in ATRP include 1-phenylethyl chloride, 1-phenylethyl bromide, chloroform, carbon tetrachloride, 2-chloropropionitrile, α,α'-dichloroxylene, α,α'-dibromoxylene, hexakis(α-bromomethyl)benzene, and alkyl esters of 2-halocarboxylic acids having 1 to 6 carbon atoms (such as methyl 2-chloropropionate, ethyl 2-chloropropionate, methyl 2-bromopropionate, ethyl 2-bromoisobutyrate, etc.). More specific examples of alkyl esters of 2-halocarboxylic acids having 1 to 6 carbon atoms include, for example, methyl 2-chloropropionate, ethyl 2-chloropropionate, methyl 2-bromopropionate, ethyl 2-bromoisobutyrate, etc.

[0086] The transition metal compounds that can be used in ATRP are those represented by M n+ X n wherein. M n+ X n For the transition metal M of the transition metal compound represented by n+ Cu + Cu 2+ Fe 2+ Fe3+ , Ru 2+ , Ru 3+ , Cr 2+ , Cr 3+ , Mo 0 , Mo + , Mo 2+ , Mo 3+ , W 2+ , W 3+ , Rh 3+ , Rh 4+ , Co + , Co 2+ ,Re 2+ ,Re 3+ , Ni 0 , Ni + , Mn 3+ , Mn 4+ , V 2+ , V 3+ , Zn + , Zn 2+ , Au + , Au 2+ , Ag + and Ag 2+ It can be selected from the group consisting of: M n+ X n X in the transition metal compound represented by the formula (I) is a halogen atom, an alkoxyl group having 1 to 6 carbon atoms, (SO4) 1 / 2 , (PO4) 1 / 3 , (HPO4) 1 / 2 , (H2PO4), triflate, hexafluorophosphate, methanesulfonate, arylsulfonate (preferably benzenesulfonate or toluenesulfonate), SeR 11 , CN and R 12 COO, where R 11 represents an aryl group or a linear or branched alkyl group having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), R 12 represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms (preferably a methyl group) which may be substituted 1 to 5 times with halogen (preferably 1 to 3 times with fluorine or chlorine). M n+ X n In the transition metal compound represented by the formula (I), n represents the formal charge on the metal and is an integer of 0 to 7.

[0087] Examples of the ligand compound capable of coordinating to the transition metal of the above transition metal compound include compounds having a ligand containing one or more nitrogen atoms, oxygen atoms, phosphorus atoms or sulfur atoms capable of coordinating to the transition metal via a σ bond, compounds having a ligand containing two or more carbon atoms capable of coordinating to the transition metal via a π bond, and compounds having a ligand capable of coordinating to the transition metal via a μ bond or an η bond.

[0088] The above transition metal complex is not particularly limited, but preferably, transition metal complexes of Groups 7, 8, 9, 10, and 11 are more preferably complexes of zero-valent copper, monovalent copper, divalent ruthenium, divalent iron or divalent nickel.

[0089] Specific examples of the catalyst that can be used in ATRP include, when the central metal is copper, complexes with ligands such as 2,2'-bipyridyl and its derivatives, 1,10-phenanthroline and its derivatives, tetramethylethylenediamine, pentamethyldiethylenetriamine, and polyamines such as hexamethyltris(2-aminoethyl)amine. Examples of the divalent ruthenium complex include dichlorotris(triphenylphosphine)ruthenium, dichlorotris(tributylphosphine)ruthenium, dichloro(cyclooctadiene)ruthenium, dichlorobenzeneruthenium, dichloro-p-cymeneruthenium, dichloro(norbornadiene)ruthenium, cis-dichlorobis(2,2'-bipyridine)ruthenium, dichlorotris(1,10-phenanthroline)ruthenium, carbonylchlorohydridotris(triphenylphosphine)ruthenium, etc. Further examples of the divalent iron complex include bis(triphenylphosphine) complex, triazacyclononane complex, etc.

[0090] In living radical polymerization, it is preferable to use a solvent. Examples of solvents used in living radical polymerization include ester-based solvents such as ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; ether-based solvents such as diisopropyl ether, dimethoxyethane, and diethylene glycol dimethyl ether; halogen-based solvents such as dichloromethane and dichloroethane; aromatic solvents such as toluene and xylene; ketone-based solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol-based solvents such as methanol, ethanol, and isopropanol; and aprotic polar solvents such as dimethylformamide and dimethyl sulfoxide. The above solvents may be used alone or in combination of two or more.

[0091] The polymerization temperature during the living radical polymerization is preferably in the range of room temperature to 120°C.

[0092] When the polymer of the present invention is produced by living radical polymerization, metals resulting from the transition metal compound used in the polymerization may remain in the resulting polymer. The metals remaining in the resulting polymer may be removed using activated alumina or the like after the polymerization is completed.

[0093] [Lubricating oil composition] The antifoaming agent of the present invention can be suitably used as an antifoaming agent for lubricating oil compositions, and the lubricating oil compositions of the present invention contain the antifoaming agent of the present invention.

[0094] The antifoaming agent of the present invention is a polymer having a crosslinked structure by using a polymerizable monomer (2) having two or more polymerizable unsaturated groups as a polymerization component, and can suppress molecular spreading of the antifoaming agent even in a high-temperature environment, thereby maintaining low solubility in the lubricating base oil, thereby allowing the antifoaming agent of the present invention to exhibit high antifoaming performance even in a high-temperature environment. Furthermore, in machines equipped with internal combustion engines or electric motors, high shearing forces are applied to the drive parts of the machines. However, the crosslinked structure of the defoaming agent of the present invention prevents the defoaming agent from being reduced in molecular weight, and therefore, the defoaming performance can be prevented from decreasing.

[0095] The defoaming agent of the present invention has high defoaming performance as described above, and can be used without limitation in lubricating oil compositions for drive system equipment such as automotive shock absorbers, transmissions, and power steering.

[0096] The content ratio of the defoaming agent of the present invention in the lubricating oil composition of the present invention is not particularly limited, and is, for example, in the range of 1 to 1,000 mass ppm of the total amount of the lubricating oil composition, preferably in the range of 5 to 700 mass ppm, and more preferably in the range of 10 to 400 mass ppm.

[0097] Known lubricating base oils can be used for the lubricating oil composition of the present invention, which may be mineral oils, synthetic oils, or mixed oils of mineral oils and synthetic oils.

[0098] Examples of mineral oils include mineral oils obtained by subjecting a lubricating oil fraction obtained by vacuum distillation of an atmospheric residue obtained by atmospheric distillation of crude oil to one or more treatments such as solvent dewaxing, solvent extraction, hydrocracking, solvent deoiling, catalytic deoiling, and hydrorefining, and paraffinic mineral oils, naphthenic mineral oils, etc. can be mentioned. In addition, mineral oils produced by isomerizing mineral oil-based waxes or waxes produced by the Fischer-Tropsch method (GTL waxes) are also included.

[0099] Examples of synthetic oils include polyolefins such as polybutene, α-olefin homopolymers and copolymers (e.g., ethylene-α-olefin copolymers), various esters such as polyol esters, dibasic acid esters, and phosphate esters, various ethers such as polyphenyl ethers, polyglycols, alkylbenzenes, alkylnaphthalenes, etc.

[0100] The lubricating base oil may be used alone or in combination of two or more.

[0101] The kinematic viscosity of the lubricating base oil at 100 °C is preferably in the range of 1 to 20 mm 2 / s, more preferably in the range of 2 to 15 mm 2in the range of / s, more preferably in the range of 2 to 10 mm 2 is in the range of / s. When the kinematic viscosity of the lubricating oil base oil at 100 °C is within the above range, the evaporation loss is small and the power loss due to viscous resistance is not too large, so the fuel consumption improvement effect is easily obtained.

[0102] The lubricating oil base oil preferably has a paraffin content (%Cp, sometimes described as such) of 70% or more by n-d-M ring analysis, more preferably 75% or more, and even more preferably 80% or more. When the paraffin content of the lubricating oil base oil is within the above range, the oxidation stability and the like are improved.

[0103] The content ratio of the lubricating oil base oil in the lubricating oil composition is, for example, in the range of 65 to 95% by mass of the total amount of the lubricating oil composition, preferably in the range of 70 to 95% by mass, and even more preferably in the range of 70 to 90% by mass.

[0104] The lubricating oil composition of the present invention may contain the defoaming agent and the lubricating oil base oil of the present invention, and may further contain other additives. As other additives, additives such as ashless detergents, ashless friction modifiers, antiwear agents, extreme pressure agents, viscosity index improvers, metal deactivators, pour point depressants, and rust inhibitors may be contained. These additives may be used alone or in combination of two or more.

[0105] The content of each of the other additives can be appropriately adjusted within a range that does not impair the effects of the present invention. Based on the total amount of the lubricating oil composition, it is usually 0.001 to 25% by mass, preferably 0.005 to 20% by mass, and more preferably 0.01 to 15% by mass. The total content of the other additives is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less based on the total amount of the lubricating oil composition.

[0106] Examples of the ashless detergent include alkenyl succinimide such as alkenyl succinic monoimide and alkenyl succinic bisimide, and boron-modified alkenyl succinimide.

[0107] Examples of the ashless friction modifier include aliphatic amines, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, etc., each having at least one alkyl group or alkenyl group having 6 to 30 carbon atoms in the molecule.

[0108] Examples of the antiwear agent or extreme pressure agent include sulfur-containing compounds such as zinc dithiophosphate; phosphorus-containing compounds such as phosphites, phosphates, phosphonates, and amine salts or metal salts thereof; sulfur- and phosphorus-containing antiwear agents such as thiophosphites, thiophosphates, thiophosphonates, and amine salts or metal salts thereof.

[0109] Examples of the viscosity index improver include polymethacrylate, dispersed polymethacrylate, olefin copolymers (e.g., ethylene-propylene copolymer, etc.), dispersed olefin copolymers, styrene copolymers (e.g., styrene-diene copolymer, styrene-isoprene copolymer, etc.).

[0110] Examples of the metal deactivator include benzotriazole-based compounds, tolyltriazole-based compounds, imidazole-based compounds, pyrimidine-based compounds, etc.

[0111] Examples of the pour point depressant include ethylene-vinyl acetate copolymer, condensate of chlorinated paraffin and naphthalene, condensate of chlorinated paraffin and phenol, polymethacrylate, polyalkylstyrene, etc.

[0112] Examples of the rust inhibitor include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic ester, polyhydric alcohol ester, etc.

[0113] The lubricating oil composition of the present invention is suitably used for lubricating the driving part of a machine equipped with an internal combustion engine or an electric motor. Regarding the lubrication of drive units, for example, in electric vehicles, the drive unit generally integrates a motor, inverter, and gearbox, and the drive unit can be lubricated by filling the gearbox with the lubricating oil composition of the present invention. Furthermore, in gasoline-powered vehicles, the drive unit of the internal combustion engine is lubricated by storing the lubricating oil composition of the present invention in an oil pan and supplying it into the cylinder via an oil pump, thereby lubricating the starting parts. The lubrication of the drive unit is not limited to these forms, and the drive unit can be lubricated by filling or supplying the lubricating oil composition of the present invention to parts where metals come into contact with each other.

[0114] The lubricating oil composition of the present invention can be used in any machine equipped with an internal combustion engine or an electric motor, including automobiles (gasoline-powered vehicles, electric vehicles), robots (industrial robots, entertainment robots), aircraft (airplanes, helicopters), ships, and various home appliances. [Example]

[0115] The present invention will be specifically described below with reference to examples and comparative examples. The present invention is not limited to the following examples.

[0116] In the examples and comparative examples, the weight average molecular weight (Mw) and number average molecular weight (Mn) are values measured by gel permeation chromatography (GPC) and converted into polystyrene equivalent values. The GPC measurement conditions are as follows:

[0117] [GPC measurement conditions] Measurement equipment: Tosoh Corporation's high-speed GPC equipment "HLC-8320GPC" Column: Tosoh Corporation "TSK GUARDCOLUMN SuperHZ-L" + Tosoh Corporation "TSK gel SuperHZM-N" + Tosoh Corporation "TSK gel SuperHZM-N" + Tosoh Corporation "TSK gel SuperHZM-N" + Tosoh Corporation "TSK gel SuperHZM-N" Detector: RI (Differential Refractometer) Data processing: "EcoSEC Data Analysis Version 1.07" manufactured by Tosoh Corporation Column temperature: 40 °C Developing solvent: Tetrahydrofuran Flow rate: 0.35 mL / min Measurement sample: A solution prepared by dissolving 7.5 mg of the sample in 10 mL of tetrahydrofuran and filtering the resulting solution through a microfilter was used as the measurement sample. Sample injection volume: 20 μL Standard sample: The following monodisperse polystyrenes with known molecular weights were used in accordance with the measurement manual of the "HLC-8320GPC".

[0118] (Monodisperse polystyrene) "A-300" manufactured by Tosoh Corporation "A-500" manufactured by Tosoh Corporation "A-1000" manufactured by Tosoh Corporation "A-2500" manufactured by Tosoh Corporation "A-5000" manufactured by Tosoh Corporation "F-1" manufactured by Tosoh Corporation "F-2" manufactured by Tosoh Corporation "F-4" manufactured by Tosoh Corporation "F-10" manufactured by Tosoh Corporation "F-20" manufactured by Tosoh Corporation "F-40" manufactured by Tosoh Corporation "F-80" manufactured by Tosoh Corporation "F-128" manufactured by Tosoh Corporation "F-288" manufactured by Tosoh Corporation

[0119] (Synthesis Example 1: Synthesis of Defoaming Agent (1)) 30 parts by mass of dipropylene glycol monomethyl ether acetate as a solvent was charged into a glass flask equipped with a stirrer, a thermometer, a condenser, and a dropping device, and the temperature was raised to 95 °C while stirring under a nitrogen stream. Next, a monomer solution prepared by dissolving 15 parts by mass of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane, 13.8 parts by mass of methoxypolyethylene glycol acrylate (with an ethylene oxide chain repeat number of about 9), and 4.5 parts by mass of polyethylene glycol dimethacrylate (with an ethylene oxide chain repeat number of about 4) in 37.7 parts by mass of dipropylene glycol monomethyl ether acetate, and a polymerization initiator solution prepared by dissolving 1 part by mass of t-butyl peroxy-2-ethylhexanoate as a radical polymerization initiator in 10 parts by mass of dipropylene glycol monomethyl ether acetate were set in different dropping devices respectively. While maintaining the inside of the flask at 95°C, the monomer solution and the polymerization initiator solution were simultaneously started to be dropped. The monomer solution was dropped over 2 hours, and the polymerization initiator solution was dropped over 2.5 hours. After the dropping of the polymerization initiator solution was completed, it was stirred at 95°C for 3 hours, then heated to 110°C and stirred for 1 hour to obtain a solution of defoamer (1).

[0120] As a result of measuring the molecular weight of the obtained defoamer (1) by GPC, the weight average molecular weight (Mw) was 33,000.

[0121] (Synthesis Example 2: Synthesis of defoamer (2)) 30 parts by mass of dipropylene glycol monomethyl ether acetate as a solvent was charged into a glass flask equipped with a stirrer, a thermometer, a condenser, and a dropping device, and the temperature was raised to 100°C while stirring under a nitrogen stream. Next, a monomer solution prepared by dissolving 15 parts by mass of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane, 13.8 parts by mass of methoxypolyethylene glycol acrylate (with an ethylene oxide chain repeat number of about 9), and 4.5 parts by mass of trimethylolpropane triacrylate in 93.2 parts by mass of dipropylene glycol monomethyl ether acetate, and a polymerization initiator solution prepared by dissolving 1.67 parts by mass of t-butyl peroxy-2-ethylhexanoate as a radical polymerization initiator in 10 parts by mass of dipropylene glycol monomethyl ether acetate were set in different dropping devices respectively. While maintaining the inside of the flask at 100 °C, the monomer solution and the polymerization initiator solution were simultaneously started to be dropped, and the monomer solution was dropped over 2 hours and the polymerization initiator solution was dropped over 2.5 hours. After the dropping of the polymerization initiator solution was completed, a solution of the defoaming agent (2) was obtained by stirring at 100 °C for 4 hours.

[0122] As a result of measuring the molecular weight of the obtained defoaming agent (2) by GPC, the weight average molecular weight (Mw) was 20,000.

[0123] (Synthesis Example 3: Synthesis of defoaming agent (3)) 30 parts by mass of dipropylene glycol monomethyl ether acetate as a solvent was charged into a glass flask equipped with a stirrer, a thermometer, a condenser tube, and a dropping device, and the temperature was raised to 105 °C while stirring under a nitrogen stream. Next, a monomer solution prepared by dissolving 15 parts by mass of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane, 13.8 parts by mass of methoxypolyethylene glycol acrylate (the number of repeating units of the ethylene oxide chain is about 9), and 4.5 parts by mass of pentaerythritol tetraacrylate in 93.2 parts by mass of dipropylene glycol monomethyl ether acetate, and a polymerization initiator solution prepared by dissolving 1.67 parts by mass of t-butylperoxy-2-ethylhexanoate as a radical polymerization initiator in 10 parts by mass of dipropylene glycol monomethyl ether acetate were set in different dropping devices, respectively. While maintaining the inside of the flask at 105 °C, the monomer solution and the polymerization initiator solution were simultaneously started to be dropped, and the monomer solution was dropped over 2 hours and the polymerization initiator solution was dropped over 2.5 hours. After the dropping of the polymerization initiator solution was completed, a solution of the defoaming agent (3) was obtained by stirring at 105 °C for 4 hours.

[0124] As a result of measuring the molecular weight of the obtained defoaming agent (3) by GPC, the weight average molecular weight (Mw) was 26,000.

[0125] (Synthesis Example 4: Synthesis of defoaming agent (4)) A glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device was charged with 30 parts by mass of dipropylene glycol monomethyl ether acetate as a solvent, and the temperature was raised to 110 °C while stirring under a nitrogen stream. Next, a monomer solution in which 15 parts by mass of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane, 13.8 parts by mass of methoxypolyethylene glycol acrylate (the number of ethylene oxide chain repetitions is about 9), and 4.5 parts by mass of dipentaerythritol hexaacrylate were dissolved in 93.2 parts by mass of dipropylene glycol monomethyl ether acetate, and a polymerization initiator solution in which 6.66 parts by mass of t-butylperoxy-2-ethylhexanoate as a radical polymerization initiator was dissolved in 10 parts by mass of dipropylene glycol monomethyl ether acetate were set in different dropping devices, respectively. While maintaining the inside of the flask at 110 °C, the dropping of the monomer solution and the polymerization initiator solution was started simultaneously. The monomer solution was dropped over 2 hours, and the polymerization initiator solution was dropped over 2.5 hours. After the dropping of the polymerization initiator solution was completed, the solution of the antifoaming agent (4) was obtained by stirring at 110 °C for 4 hours.

[0126] As a result of measuring the molecular weight of the obtained antifoaming agent (4) by GPC, the weight average molecular weight (Mw) was 13,000.

[0127] (Synthesis Example 5: Synthesis of antifoaming agent (5)) A glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device was charged with 30 parts by mass of n-butyl acetate as a solvent, and the temperature was raised to 100 °C while stirring under a nitrogen stream. Next, two types of dropping liquids were placed in different dropping devices: a monomer solution prepared by dissolving 15 parts by mass of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane, 13.8 parts by mass of methoxypolyethylene glycol acrylate (the number of repeating ethylene oxide chains is approximately 9), and 4.5 parts by mass of tris(2-acryloyloxyethyl)isocyanurate in 78.1 parts by mass of n-butyl acetate; and a polymerization initiator solution prepared by dissolving 1.67 parts by mass of t-butylperoxy-2-ethylhexanoate as a radical polymerization initiator in 10 parts by mass of n-butyl acetate. While maintaining the temperature inside the flask at 100° C., the monomer solution and the polymerization initiator solution were simultaneously added dropwise, over 2 hours for the monomer solution and 2.5 hours for the polymerization initiator solution. After the addition of the polymerization initiator solution was completed, the mixture was stirred at 100° C. for 3 hours, then heated to 110° C. and stirred for an additional hour to obtain a solution of defoamer (5).

[0128] The molecular weight of the obtained antifoaming agent (5) was measured by GPC, and the weight average molecular weight (Mw) was found to be 14,000.

[0129] (Synthesis Example 6: Synthesis of antifoaming agent (6)) A glass flask equipped with a stirrer, a thermometer, a condenser, and a dropping device was charged with 30 parts by mass of dipropylene glycol monomethyl ether acetate as a solvent, and the temperature was raised to 110°C while stirring under a nitrogen stream. Next, two types of dropping liquids were placed in different dropping devices: a monomer solution prepared by dissolving 12.5 parts by mass of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane and 12.5 parts by mass of polyethylene glycol dimethacrylate (the number of repeating ethylene oxide chains is approximately 9) in 60 parts by mass of dipropylene glycol monomethyl ether acetate; and a polymerization initiator solution prepared by dissolving 7.5 parts by mass of t-butylperoxy-2-ethylhexanoate as a radical polymerization initiator in 10 parts by mass of dipropylene glycol monomethyl ether acetate. While maintaining the inside of the flask at 110 °C, the monomer solution and the polymerization initiator solution were simultaneously started to be dropped, and the monomer solution was dropped over 2 hours and the polymerization initiator solution was dropped over 2.5 hours. After the dropping of the polymerization initiator solution was completed, a solution of the antifoaming agent (5) was obtained by stirring at 110 °C for 2 hours.

[0130] As a result of measuring the molecular weight of the obtained antifoaming agent (5) by GPC, the weight average molecular weight (Mw) was 15,000.

[0131] (Synthesis Comparative Example 1: Synthesis of Antifoaming Agent (1’)) 52 parts by mass of n-butyl acetate as a solvent was charged into a glass flask equipped with a stirrer, a thermometer, a condenser, and a dropping device, and the temperature was raised to 85 °C while stirring under a nitrogen stream. Next, 30 parts by mass of 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane dissolved in 50 parts by mass of n-butyl acetate, 20 parts by mass of methoxypolyethylene glycol methacrylate (the number of repeating units of the ethylene oxide chain is about 9), and 3 parts by mass of t-butylperoxy-2-ethylhexanoate as a radical polymerization initiator dissolved in 15 parts by mass of n-butyl acetate were set as two types of dropping liquids in separate dropping devices, respectively. While maintaining the inside of the flask at 85 °C, the monomer solution and the polymerization initiator solution were simultaneously dropped over 2 hours. After the dropping was completed, the mixture was stirred at 85 °C for 4 hours, then the temperature was raised to 110 °C, and further stirred for 1 hour to obtain a solution of the antifoaming agent (1’).

[0132] As a result of measuring the molecular weight of the obtained antifoaming agent (1’) by GPC, the weight average molecular weight (Mw) was 40,000.

[0133] (Synthesis Comparative Example 2: Synthesis of Antifoaming Agent (2’)) A solution of the antifoaming agent (2’) was obtained in the same manner as in Synthesis Comparative Example 1, except that 30 parts by mass of the compound represented by the following formula (1’) was used instead of 3-methacryloyloxypropyltris(trimethylsiloxy)silane.

[0134]

Chemical formula

[0135] As a result of measuring the molecular weight of the obtained antifoaming agent (2’) by GPC, the weight average molecular weight (Mw) was 25,000.

[0136] (Comparative Example 3) A commercially available dimethyl silicone (manufactured by Shin-Etsu Silicone Co., Ltd., "KF-96-50000cs") represented by the following was separately prepared as an antifoaming agent (3’).

[0137] [Chemical formula]

[0138] Using the antifoaming agent manufactured above, the following foaming test was conducted to evaluate the antifoaming performance of the antifoaming agent. The results are shown in Table 1.

[0139] (Preparation of lubricating oil composition) To 100 parts by mass of a base lubricating oil mainly composed of a lubricating oil base oil (paraffin-based mineral oil) and containing a small amount of various additives (viscosity index improver, phosphite compound, thiadiazole compound, calcium-based detergent, metal deactivator, ashless dispersant, antioxidant, etc.), the antifoaming agent shown in Table 1 diluted with kerosene was added in the amount shown in Table 1 to obtain a lubricating oil composition.

[0140] The following foaming test was carried out on the obtained lubricating oil composition. The results are shown in Table 1. (Foaming test) The foaming test was carried out in accordance with the homogenizer method disclosed in JP-A-2008-120880. Using a homogenizer (T.K. Robomix manufactured by Primix Corporation) equipped with a generator shaft (Mini Mixer manufactured by Primix Corporation), the lubricating oil composition was stirred according to the following conditions. After the stirring was completed, the reading (mL) of the oil level before stirring was subtracted from the reading (mL) of the foaming surface 3 seconds after the stirring was completed, and the amount of foaming (mL) was obtained. The smaller the amount of foaming, the better the defoaming property. Rotation speed: 16,000 rpm Oil temperature: 80 °C or 120 °C Oil volume: 80 ml Container: 200 ml graduated cylinder (inner diameter φ36 mm) Stirring time: 1 minute

[0141]

Table 1

[0142] From the results in Table 1, it can be confirmed that the defoamers (1) to (6) can exhibit excellent defoaming properties in any temperature environment of 80 °C and 120 °C. On the other hand, for the defoamer (1’) that does not use the “polymerizable monomer (2) having two or more polymerizable unsaturated groups”, sufficient defoaming property has not been obtained. For the defoamer (2’), the defoaming property at 80 °C has been obtained by introducing a polysiloxane structure, but sufficient defoaming property has not been obtained at 120 °C.

Claims

1. -Si[OSi(R) ３ ｎ [R'] ３－ｎ (n is an integer in the range of 1 to 3. Each R is independently an alkyl group having 1 to 3 carbon atoms. Each R' is independently an alkyl group having 1 to 3 carbon atoms), and contains a polymer having at least a polymerizable monomer (1) having a functional group represented by and having one polymerizable unsaturated group and a polymerizable monomer (2) having two or more polymerizable unsaturated groups as polymerization components. An antifoaming agent.​

2. The defoaming agent according to claim 1, wherein the polymerizable monomer (1) is a compound represented by the following general formula (1-1). 【Chemical 1】 (In the general formula (1-1), each R is independently an alkyl group having 1 to 3 carbon atoms each R' is independently an alkyl group having 1 to 3 carbon atoms.) L １１ is a divalent organic group or a single bond. n is an integer in the range of 1 to 3.) P is a polymerizable group represented by the general formula (P-1), a polymerizable group represented by the general formula (P-2), or a polymerizable group represented by the general formula (P-3). In the general formula (P-1), the general formula (P-2), and the general formula (P-3), R １１ is a hydrogen atom or a methyl group. R １２ is a hydrogen atom or an organic group. R １３ is a hydrogen atom or a methyl group. * is a bonding hand that bonds to L １１ and is a bonding hand that bonds to it.)

3. The defoaming agent according to claim 1 or 2, wherein the content of the polymerizable monomer (1) is in the range of 10% by mass or more based on the total amount of the polymerization components of the polymer.

4. The defoaming agent according to claim 1 or 2, wherein the polymerizable monomer (2) is a compound represented by the following general formula (2-1). 【Chemical Formula 2】 (In the general formula (2-1), R ２１ is a hydrogen atom or a methyl group. x is an integer of 2 or more.) L ２１ is an organic group of x valence.)

5. The defoaming agent according to claim 1 or 2, wherein the content of the polymerizable monomer (2) is in the range of 1 to 75% by mass based on the total amount of the polymerization components of the polymer.

6. The defoaming agent according to claim 1 or 2, wherein the polymerization component contains at least one polymerizable monomer (3) selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an aromatic group having 6 to 18 carbon atoms, a group containing a polyoxyalkylene chain, and a group containing a polyester chain.

7. The defoaming agent according to claim 6, wherein the polymerizable monomer (3) is at least one selected from the group consisting of a compound represented by the following general formula (3-1), a compound represented by the following general formula (3-2), a compound represented by the following general formula (3-3), a compound represented by the following general formula (3-4), and a compound represented by the following general formula (3-5). 【Chemical Formula 3】 (In the general formulas (3-1), (3-2), (3-3), (3-4), and (3-5), R ３１ is a hydrogen atom or a methyl group, R ３２ is an alkyl group having 1 to 18 carbon atoms, R ３３ is a hydrogen atom or a methyl group, R ３４ is a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, R ３５ is a hydrogen atom or a methyl group, R ３６ is an alkyl group having 1 to 18 carbon atoms, an alkyl group having an ether bond with 1 to 18 carbon atoms, or a hydrogen atom, R ３７ is a hydrogen atom or a methyl group, R ３８ is an alkyl group having 1 to 18 carbon atoms, an alkyl group having an ether bond with 1 to 18 carbon atoms, or a hydrogen atom, L ３ is a divalent organic group or a single bond, R ３９ is a hydrogen atom or a methyl group, R ４０ is each independently an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, n is an integer in the range of 1 to 4, m represents the number of repetitions, the number average value of m is in the range of 1 to 200, p is an integer in the range of 1 to 10, q represents the number of repetitions, the number average value of q is in the range of 1 to 100, and l is an integer in the range of 0 to 5.)

8. The defoaming agent according to claim 7, wherein the polymerizable monomer (3) contains the compound represented by the general formula (3-2).

9. The defoaming agent according to claim 6, wherein the content of the polymerizable monomer (3) is in the range of 0 to 75% by mass based on the total amount of the polymerization components of the polymer.

10. The defoaming agent according to Claim 1 or 2, wherein the weight average molecular weight of the polymer is in the range of 2,000 to 200,000.

11. A lubricating oil composition containing a lubricating base oil and the defoaming agent according to Claim 1.

12. In a machine equipped with an internal combustion engine or an electric motor, the lubricating oil composition according to Claim 11, which is used for lubricating the driving part of the machine.

13. In an automobile equipped with an internal combustion engine or an electric motor, the lubricating oil composition according to Claim 11, which is used for lubricating the driving part of the automobile.

14. A machine using the lubricating oil composition according to Claim 11 for the driving part.

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