Defoaming agent, lubricating oil composition comprising same, and machine using lubricating oil composition

Abstract

Provided is a defoaming agent which exhibits excellent defoaming properties even in a high-temperature environment. Specifically, the defoaming agent is a polymer having, as a polymerization component, at least a polymerizable monomer (A) having two or more groups represented by general formula (a) (R11 is independently a C1-6 alkyl group, a phenyl group, or a group represented by-OSi (R14) 3 (R14 is independently a C1-6 alkyl group or a phenyl group), R12 is independently a C1-6 alkyl group or a phenyl group, and R12 is independently a C1-6 alkyl group or a phenyl group. R13 represents an alkyl group or a phenyl group having 1-6 carbon atoms, and x represents the number of repetitions. ). # imgabs0 #

Description

Technical Field

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

[0002] In recent years, reducing carbon dioxide emissions has become an important theme in the industry. Among them, carbon dioxide emissions from transportation equipment including automobiles account for nearly 20% of total emissions. As one of the measures to reduce carbon dioxide emissions, various countries have proposed converting gasoline vehicles to electric vehicles (EVs) in their policies.

[0003] The most important issue in EV is to improve fuel consumption. To this end, research on miniaturization of vehicle bodies and efficient drive systems is being rapidly promoted. One of the issues in efficient drive systems is the foaming of lubricating oil. In order to reduce frictional resistance, the lubricating oil is being promoted to have a low viscosity, but the low viscosity makes it easy to foam. In addition, in EVs, due to the miniaturization of the drive system, the gap is reduced, and the tolerance for foaming is also reduced.

[0004] If high-load operation or high-speed driving is carried out continuously, the following problems may sometimes occur: the foaming in the low-viscosity lubricating oil increases, and the lubrication performance and cooling efficiency are reduced due to the foaming; wear and sintering occur due to the rupture of the oil film at the friction site; and the deterioration of the lubricating oil is accelerated due to the increase in oil temperature.

[0005] Therefore, lubricating oil with high defoaming property is required, and a defoaming agent is added to the lubricating oil to prevent foaming. As such defoaming agent, silicone defoaming agents are known, and various silicone defoaming agents have been proposed (for example, Patent Documents 1 to 4).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2014-62259

[0009] Patent Document 2: WO2015 / 087628

[0010] Patent Document 3: Japanese Patent Publication No. 2008-542462

[0011] Patent Document 4: Japanese Patent Publication No. 2008-542010 Summary of the invention

[0012] Problems to be solved by the invention

[0013] Conventional silicone-based defoamers have a problem that their defoaming properties significantly decrease as the temperature rises. For example, in automotive applications that require defoaming properties at high temperatures, there is a problem that sufficient defoaming properties cannot be obtained.

[0014] An object of the present invention is to provide a defoaming agent that exhibits excellent defoaming properties even in a high-temperature environment.

[0015] Another problem to be solved by the present invention is to provide a lubricating oil composition that can exhibit excellent lubrication performance even in a high-temperature environment.

[0016] Technical means of solving problems

[0017] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found that a polymer having at least two or more specific silicone chain-containing functional groups as a polymerization component is a defoaming agent that exhibits excellent defoaming properties even in a high-temperature environment, thereby completing the present invention.

[0018] That is, the present invention relates to a defoaming agent which is a polymer containing at least a polymerizable monomer (A) having two or more groups represented by the following general formula (a) as a polymerization component.

[0019] [Chemistry 1]

[0020]

[0021] (In the general formula (a),

[0022] R 11 are independently an alkyl group having 1 to 6 carbon atoms, a phenyl group or -OSi(R 14 )3 represented by the group (R 14 are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group),

[0023] R 12 are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group,

[0024] R 13 is an alkyl group having 1 to 6 carbon atoms or a phenyl group,

[0025] x represents the number of repetitions)

[0026] Effects of the Invention

[0027] According to the present invention, a defoaming agent that exhibits excellent defoaming properties even in a high-temperature environment can be provided.

[0028] According to the present invention, a lubricating oil composition that can exhibit excellent lubrication performance even in a high-temperature environment can be provided. DETAILED DESCRIPTION

[0029] Hereinafter, an embodiment of the present invention will be described. The present invention is not limited to the following embodiment, and can be implemented by appropriately adding changes within a range that does not impair the effects of the present invention.

[0030] [Defoaming agent]

[0031] The defoaming agent of the present invention is a polymer containing, as a polymerization component, a polymerizable monomer (A) having at least two groups represented by the following general formula (a).

[0032] [Chemistry 2]

[0033]

[0034] (In the general formula (a),

[0035] R 11 are independently an alkyl group having 1 to 6 carbon atoms, a phenyl group or -OSi(R 14 )3 represented by the group (R 14 are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group),

[0036] R 12 are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group,

[0037] R 13 is an alkyl group having 1 to 6 carbon atoms or a phenyl group,

[0038] x represents the number of repetitions)

[0039] In the defoamer of the present invention, one polymerizable monomer has two or more silicone chain-containing functional groups represented by the general formula (a), thereby increasing the density of the silicone chain-containing functional groups of the polymer. As a result, the surface tension reduction capability is improved, and the defoamer can easily and efficiently move to the air interface, thereby exhibiting high defoaming properties even in a high temperature environment.

[0040] In the present invention, the "polymerization component" refers to a component constituting a polymer, and does not include a solvent or a polymerization initiator that does not constitute a polymer.

[0041] In the present invention, the term "polymerizable monomer" refers to a compound having a polymerizable unsaturated group, and examples of the polymerizable unsaturated group possessed by the polymerizable monomer (A) include C=C-containing groups such as a (meth)acryloyl group, a (meth)acryloyloxy group, a (meth)acryloylamino group, a vinyl ether group, an allyl group, a styryl group, and a maleimide group. Among these, a (meth)acryloyl group and a (meth)acryloyloxy group are preferred in terms of easy availability of raw materials and good polymerization reactivity.

[0042] The number of polymerizable unsaturated groups contained in the polymerizable monomer may be one or two or more.

[0043] In the general formula (a), R 11 Preferably, methyl or trimethylsilyl is 12 and R 13 Preferred is methyl.

[0044] R 11 , R 12 , R 13 and R 14 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.

[0045] R 11 , R 12 , R 13 and R 14 The phenyl group may further have a substituent, and examples of the substituent include a hydroxyl group and an alkyl group.

[0046] In the general formula (a), x represents the number of repetitions, and for example, x may be an integer of 1 or more.

[0047] The number of x is, for example, in the range of 1 to 150, preferably in the range of 1 to 100, more preferably in the range of 1 to 45, and even more preferably in the range of 1 to 35 on average.

[0048] The number average value of x can be confirmed by measuring the number average molecular weight of the polymerizable monomer (A) by the method described in Examples.

[0049] In the general formula (a), a plurality of R 11 They may be the same or different from each other. 12 They may be the same as or different from each other.

[0050] The polymerizable monomer (A) is preferably a compound represented by the following general formula (a-1).

[0051] [Chemistry 3]

[0052]

[0053] (In the general formula (a-1),

[0054] R 11 , R 12 , R 13 and x are respectively the same as R 11 , R 12 , R 13 and x are the same,

[0055] R 15 is a hydrogen atom or a methyl group,

[0056] L 11 and L 13 are independently a divalent organic group or a single bond,

[0057] y is an integer in the range of 2 to 5,

[0058] L 12 is an organic group with a valence of y+1)

[0059] L 11 and L 13 It is preferably a single bond, an alkylene group having 1 to 50 carbon atoms, or an alkyleneoxy group having 1 to 50 carbon atoms.

[0060] As L 11 and L 13 The alkylene group having 1 to 50 carbon atoms includes methylene, ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, n-decylene, n-dodecylene, isopropylene, 2-methylpropylene, 2-methylhexylene, tetramethylethylene and the like.

[0061] L 11 and L 13 The alkylene group having 1 to 50 carbon atoms is preferably an alkylene group having 1 to 15 carbon atoms, more preferably an alkylene group having 1 to 5 carbon atoms, further preferably a methylene group, an ethylene group, an n-propylene group or an isopropylene group.

[0062] L 11 and L 13 The alkyleneoxy group having 1 to 50 carbon atoms is, for example, a group in which one -CH2- in the alkylene group is substituted with -O-.

[0063] L 11 and L 13 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, further 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.

[0064] In L 11 and L 13 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 part of the -CH2- of these divalent organic groups can be replaced by a carbonyl group (-C(=O)-), a phenylene group, a thioether bond (-S-), an amide bond or a carbamate bond, and further, a hydroxyl group etc. can be replaced by a carbon atom.

[0065] L 12 Examples of the y+1-valent organic group include a carbon atom and a benzene ring.

[0066] The polymerizable monomer (A) can be produced, for example, by reacting a polymerizable monomer having a silicone chain-containing functional group with an alcohol having two or more mercapto groups to synthesize a precursor having two or more silicone chain-containing functional groups and a hydroxyl group, and reacting the precursor with a polymerizable monomer having an isocyanate group.

[0067] The following chemical formula is an example of a synthetic route when carrying out the above-mentioned production method, and a compound represented by the general formula (a-1-1) can be produced as a polymerizable monomer (A).

[0068] [Chemistry 4]

[0069]

[0070] (Where R 16 is a hydrogen atom or a methyl group)

[0071] [Chemistry 5]

[0072]

[0073] (Where,

[0074] R 17 is a hydrogen atom or a methyl group,

[0075] L 14 is a divalent organic group or a single bond)

[0076] In the general formula (a-1-1), L 14 The divalent organic group includes L 11 The same group as the divalent organic group.

[0077] The polymerizable monomer (A) constituting the polymer as a defoaming agent of the present invention (hereinafter sometimes simply referred to as "polymer of the present invention") may be a single species or two or more species.

[0078] The weight average molecular weight of the polymerizable monomer (A) is preferably in the range of 100 to 4,000.

[0079] Here, the "weight average molecular weight" is a value measured by the method described in Examples.

[0080] In the polymer of the present invention, the lower limit of the content ratio of the polymerizable monomer (A) in the polymerization component (hereinafter referred to as "the content ratio of the polymerizable monomer (A)") is, for example, 5 mass % or more, and preferably 10 mass % or more, 15 mass % or more, 20 mass % or more, 30 mass % or more, and 40 mass % or more in this order.

[0081] The upper limit of the content of the polymerizable monomer (A) is not particularly limited, but is preferably 95 mass % or less, 90 mass % or less, 85 mass % or less, 80 mass % or less, 75 mass % or less, and 70 mass % or less, for example.

[0082] The content of the polymerizable monomer (A) can be adjusted by adjusting the charging ratio of the polymerizable monomer (A) when producing the polymer of the present invention.

[0083] The ratio of the polymerizable monomer (A) in the total amount of the polymerization components is preferably in the range of 20% by mass to 80% by mass.

[0084] The polymer of the present invention preferably further contains a polymerizable monomer (B) as a polymerization component, wherein the polymerizable monomer (B) has 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.

[0085] The alkyl group having 1 to 18 carbon atoms possessed by the polymerizable monomer (B) may be any of a linear alkyl group, a branched alkyl group and a cyclic alkyl group, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, an n-octyl group, and a hexadecyl group.

[0086] The alkyl group having 1 to 18 carbon atoms in the polymerizable monomer (B) is preferably an alkyl group having 1 to 6 carbon atoms.

[0087] Examples of the aromatic group having 6 to 18 carbon atoms which the polymerizable monomer (B) has include a phenyl group, a naphthyl group, anthracene-1-yl group, and a phenanthrene-1-yl group.

[0088] The group containing a (poly)oxyalkylene chain contained in the polymerizable monomer (B) is a monovalent group containing a repeating portion of an oxyalkylene group or a divalent linking group containing a repeating portion of an oxyalkylene group.

[0089] The group containing a polyester chain contained in the polymerizable monomer (B) 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.

[0090] The alkyl group having 1 to 18 carbon atoms in the polymerizable monomer (B) may further have a substituent, and examples of the substituent include a hydroxyl group and an aryl group.

[0091] The aromatic group having 6 to 18 carbon atoms in the polymerizable monomer (B) may further have a substituent, and examples of the substituent include a hydroxyl group and an alkyl group.

[0092] Examples of the polymerizable monomer (B) having an alkyl group having 1 to 18 carbon atoms and a (meth)acryloyl group as the polymerizable unsaturated group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. , alkyl esters of (meth)acrylic acid having 1 to 18 carbon atoms, such as decyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate; cross-linked cyclic alkyl esters of (meth)acrylic acid having 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, and dicyclopentenyl (meth)acrylate.

[0093] In addition, in this application, "(meth)acrylate" refers to both methacrylate and acrylate.

[0094] Examples of the polymerizable monomer (B) having a phenylalkyl group having 7 to 18 carbon atoms or a phenoxyalkyl group having 7 to 18 carbon atoms and in which the polymerizable unsaturated group is a (meth)acryloyl group include benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, and 2-phenoxyethyl (meth)acrylate.

[0095] Examples of the polymerizable monomer (B) having an alkyl group having 1 to 18 carbon atoms and in which the polymerizable unsaturated group is 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, and cyclohexyl vinyl ether; and cycloalkyl vinyl ethers.

[0096] Examples of the polymerizable monomer (B) having an aromatic group having 6 to 18 carbon atoms include styrene, α-methylstyrene, p-methylstyrene, and p-methoxystyrene.

[0097] Examples of the polymerizable monomer (B) having an alkyl group having 1 to 18 carbon atoms and a (meth)acryloylamino group as the polymerizable unsaturated group include N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, diacetoneacrylamide, and acryloylmorpholine.

[0098] Examples of the polymerizable monomer (B) having an alkyl group having 1 to 18 carbon atoms and a maleimide group as the polymerizable unsaturated group include methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, and cyclohexylmaleimide.

[0099] Examples of the polymerizable monomer (B) having a group containing a polyoxyalkylene chain and in which the polymerizable unsaturated group is 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-polypropylene glycol mono(meth)acrylate, Poly(propylene glycol-tetramethylene glycol) mono(meth)acrylate, poly(propylene glycol-tetramethylene glycol) mono(meth)acrylate, poly(propylene glycol-polytetramethylene glycol) mono(meth)acrylate, poly(propylene glycol-1,2-butylene glycol) mono(meth)acrylate, poly(propylene glycol-poly 1,2-butylene glycol) mono(meth)acrylate, poly(ethylene glycol-1,2-butylene glycol) mono(meth)acrylate, polyethylene glycol-poly 1,2-butylene glycol mono(meth)acrylate, poly(tetraethylene glycol-1,2-butylene glycol) mono(meth)acrylate acrylate, polytetraethylene glycol-poly 1,2-butylene glycol mono(meth)acrylate, poly 1,2-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 Methyl glycol mono(meth)acrylate, poly(1,2-butylene glycol-trimethylene glycol) mono(meth)acrylate, poly(1,2-butylene glycol-polytrimethylene 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.

[0100] Furthermore, the “poly(ethylene glycol-propylene glycol)” refers to a random copolymer of ethylene glycol and propylene glycol, and the “polyethylene glycol-polypropylene glycol” refers to a block copolymer of ethylene glycol and propylene glycol.

[0101] The polymerizable monomer (B) is preferably one or more selected from the group consisting of a compound represented by the following general formula (b-1), a compound represented by the following general formula (b-2), a compound represented by the following general formula (b-3), a compound represented by the following general formula (b-4), and a compound represented by the following general formula (b-5).

[0102] [Chemistry 6]

[0103]

[0104] (In the general formula (b-1), general formula (b-2), general formula (b-3), general formula (b-4) and general formula (b-5),

[0105] R 21 is a hydrogen atom or a methyl group,

[0106] R 22 is an alkyl group having 1 to 18 carbon atoms or a phenyl group,

[0107] R 23 is a hydrogen atom or a methyl group,

[0108] R 24 is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or a phenyl group,

[0109] R 25 is a hydrogen atom or a methyl group,

[0110] R 26 is an alkyl group having 1 to 18 carbon atoms, or an alkyl group having 1 to 18 carbon atoms and having an ether bond,

[0111] R 27 is a hydrogen atom or a methyl group,

[0112] R 28 is an alkyl group having 1 to 18 carbon atoms or an alkyl group having 1 to 18 carbon atoms and having an ether bond,

[0113] R 29 is a hydrogen atom or a methyl group,

[0114] R 30 are each independently an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms,

[0115] L 2 is a divalent organic group or a single bond,

[0116] n is an integer ranging from 1 to 4,

[0117] m represents the number of repetitions,

[0118] p is an integer in the range of 1 to 10,

[0119] q represents the number of repetitions,

[0120] l is an integer in the range of 0 to 5)

[0121] In the general formula (b-2), the m n's in the brackets may be the same as or different from each other.

[0122] In the general formula (b-3), the q p's in the brackets may be the same as or different from each other.

[0123] In the general formula (b-4), the q p's in the brackets may be the same as or different from each other.

[0124] R 22 , R 24 , R 26 and R 28 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.

[0125] R 22 and R 24 The phenyl group may further have a substituent, and examples of the substituent include a hydroxyl group and an alkyl group.

[0126] R 26 and R 28 The alkyl group having 1 to 18 carbon atoms and having an ether bond may further have a substituent, and examples of the substituent include a hydroxyl group and an aryl group.

[0127] 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.

[0128] R 30 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.

[0129] L in the general formula (b-3) and the general formula (b-4) 2 The divalent organic group can be exemplified by L 1 The same group as the divalent organic group.

[0130] In the general formula (b-2), m represents the number of repetitions, and for example, m may be an integer greater than 1. The number of m is, for example, in the range of 1 to 200, preferably 1 to 150, and more preferably 1 to 100 on average.

[0131] The number average value of m can be confirmed by measuring the number average molecular weight of the polymerizable monomer (B) by the method described in Examples.

[0132] In the general formula (b-3) and the general formula (b-4), q represents the number of repetitions, and q may be an integer greater than 1. The number of q is, for example, in the range of 1 to 100, preferably 1 to 80, and more preferably 1 to 50 on average.

[0133] The number average value of q can be confirmed by measuring the number average molecular weight of the polymerizable monomer (B) by the method described in Examples.

[0134] The polymerizable monomer (B) preferably contains at least a compound represented by the general formula (b-2).

[0135] By using the compound represented by the general formula (b-2) as a polymerization component, excellent compatibility with the lubricating base oil described below can be obtained.

[0136] The polymerizable monomer (B) can be produced by a known method.

[0137] In addition, commercial products can be used for the polymerizable monomer (B). For example, as commercial products of the polymerizable monomer (B) having a group containing a polyoxyalkylene chain and a polymerizable unsaturated group being a (meth)acryloyl group, there can be mentioned "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-600" manufactured by NOF Corporation. 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", Placel F series manufactured by Daicel Co., Ltd., Viscoat series manufactured by Osaka Organic Chemical Industry Co., Ltd., etc.

[0138] The polymerizable monomer (B) constituting the polymer of the present invention may be a single species or two or more species.

[0139] The mass ratio of the polymerizable monomer (A) to the polymerizable monomer (B) in the defoaming agent of the present invention satisfies, for example, polymerizable monomer (A): polymerizable monomer (B) = 5:95 to 95:5, preferably polymerizable monomer (A): polymerizable monomer (B) = 20:80 to 90:10, more preferably polymerizable monomer (A): polymerizable monomer (B) = 30:70 to 80:20, and even more preferably polymerizable monomer (A): polymerizable monomer (B) = 30:70 to 70:30.

[0140] The polymer of the present invention preferably further contains a polymerizable monomer (C) having one group represented by the general formula (a) as a polymerization component.

[0141] By combining the polymerizable monomer (A) having two or more silicone chain-containing functional groups and the polymerizable monomer (C) having one silicone chain-containing functional group, the defoaming property of the defoaming agent can be further improved.

[0142] The polymerizable monomer (C) is preferably a compound represented by the following general formula (c-1).

[0143] [Chemistry 7]

[0144]

[0145] (In the general formula (c-1),

[0146] R 11 , R 12 , R 13 and x are respectively the same as R 11 , R 12 , R 13 and x are the same,

[0147] R 35 is a hydrogen atom or a methyl group,

[0148] L 3 is a divalent organic group or a single bond)

[0149] L 3 The divalent organic group and the L 11 and L 13 The divalent organic group is the same.

[0150] In the polymer of the present invention, the content of the polymerizable monomer (C) in the polymer component is, for example, in the range of 0 to 50 mass %, preferably 3 to 30 mass %, more preferably 5 to 20 mass %.

[0151] The content of the polymerizable monomer (C) can be adjusted by adjusting the raw material charging ratio of the polymerizable monomer (C) when producing the defoaming agent of the present invention.

[0152] The defoamer of the present invention may be a polymer having at least the polymerizable monomer (A) as a polymer component, and its polymerization form is not particularly limited. For example, when the defoamer of the present invention is a copolymer having at least the polymerizable monomer (A), the polymerizable monomer (B) and / or the polymerizable monomer (C) as polymer components, the copolymer may be a random copolymer or a block copolymer.

[0153] The polymer of the present invention may contain at least the polymerizable monomer (A), any polymerizable monomer (B), and any polymerizable monomer (C) as polymerization components, and may contain other polymerizable monomers other than the polymerizable monomer (A), the polymerizable monomer (B), and the polymerizable monomer (C) as polymerization components within a range not impairing the effects of the present invention.

[0154] The polymer of the present invention is preferably a copolymer substantially composed of a polymerizable monomer (A), an arbitrary polymerizable monomer (B) and an arbitrary polymerizable monomer (C), and more preferably a copolymer consisting only of a polymerizable monomer (A), an arbitrary polymerizable monomer (B) and an arbitrary polymerizable monomer (C). Here, "substantially composed" means that the total content ratio of the polymerizable monomer (A), the arbitrary polymerizable monomer (B) and the arbitrary polymerizable monomer (C) in the polymer component is 75% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more.

[0155] The polymer of the present invention preferably contains no fluorine atoms.

[0156] 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.

[0157] 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, further preferably in the range of 2,000 to 200,000, particularly preferably in the range of 3,000 to 15,000.

[0158] In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values ​​measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0159] The values ​​of the number average molecular weight (Mn) and weight average molecular weight (Mw) of the polymer of the present invention are measured by the method described in Examples.

[0160] [Method for producing polymer]

[0161] The method for producing the polymer of the present invention is not particularly limited, and the polymer can be produced by a known method.

[0162] The polymer of the present invention can be produced by solution polymerization, bulk polymerization, emulsion polymerization, etc. based on polymerization mechanisms such as free radical polymerization, cationic polymerization, anionic polymerization, etc. For example, in the case of free radical polymerization, the polymer of the present invention can be produced by adding a polymerizable monomer mixture to an organic solvent and adding a general free radical polymerization initiator.

[0163] As the polymerization initiator, various polymerization initiators can be used, for example, peroxides such as tert-butyl peroxy-2-ethylhexanoate, benzoyl peroxide, diacyl peroxide; azo compounds such as azobisisobutyronitrile, dimethyl azobisisobutyrate, phenylazotriphenylmethane; metal chelate compounds such as Mn(acac)3, etc.

[0164] If necessary, a chain transfer agent such as lauryl mercaptan, 2-mercaptoethanol, ethylthioglycolic acid, octylthioglycolic 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.

[0165] Examples of the organic solvent include alcohols such as ethanol, isopropanol, n-butanol, isobutanol, and tert-butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone; esters such as methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, and 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, and butyl 2-methoxypropionate; dimethyl propionate; Polar solvents such as formamide, dimethyl sulfoxide, and N-methylpyrrolidone; ethers such as methyl cellosolve, cellosolve, butyl cellosolve, butyl carbitol, and ethyl cellosolve acetate; propylene glycols and esters thereof such as propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monobutyl ether acetate; halogen solvents such as 1,1,1-trichloroethane and chloroform; ethers such as tetrahydrofuran and dioxane; aromatics such as benzene, toluene, and xylene; and fluorinated inert liquids such as perfluorooctane and perfluorotri-n-butylamine.

[0166] These solvents may be used alone or in combination of two or more.

[0167] The polymer of the present invention can also be produced by living polymerization such as living radical polymerization and living anion polymerization.

[0168] In living radical polymerization, a dormant species protected by an atom or an atomic group at the active polymerization end can be reversibly generated to generate free radicals and react with a monomer, thereby performing a growth reaction. Even if the first monomer is consumed, the growth end will not lose activity, and reacts with the second monomer added successively to obtain a block polymer. Examples of such living radical polymerization include: atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT), nitroxide-mediated polymerization (NMP), and free radical polymerization using organic tellurium (TERP). Among these methods, there is no particular restriction on which method is used, but ATRP is preferred in terms of ease of control. ATRP is a polymerization initiator using an organic halide or a halogenated sulfonyl compound as a catalyst and a metal complex containing a transition metal compound and a ligand as a catalyst.

[0169] Specific examples of the polymerization initiator that can be used in ATRP include 1-phenylethyl chloride, 1-phenylethyl bromide, chloroform, carbon tetrachloride, 2-chloropropionitrile, α,α'-dichloroxylene, α,α'-dibromoxylene, hexa(α-bromomethyl)benzene, and alkyl esters of 2-halogenated carboxylic acids having 1 to 6 carbon atoms (e.g., 2-chloropropionic acid, 2-bromopropionic acid, 2-chloroisobutyric acid, 2-bromoisobutyric acid, etc.).

[0170] More specific examples of the C1-6 alkyl ester of a C1-6 2-halogenated carboxylic acid include methyl 2-chloropropionate, ethyl 2-chloropropionate, methyl 2-bromopropionate, and ethyl 2-bromoisobutyrate.

[0171] The transition metal compounds that can be used in ATRP are M n+ X n The compound represented.

[0172] As M n+ X n The transition metal M of the transition metal compound represented by n+ , free Cu + , Cu 2+ , Fe 2+ , Fe 3+ 、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+ Select from the group you want to form.

[0173] M n+ X n X of the transition metal compound represented by the present invention may be a halogen atom, an alkoxy group having 1 to 6 carbon atoms, (SO4) 1 / 2 、(PO4) 1 / 3 、(HPO4) 1 / 2 , (H2PO4), trifluoromethanesulfonate, hexafluorophosphate, methanesulfonate, arylsulfonate (preferably benzenesulfonate or toluenesulfonate), SeR 11 , CN and R 12 Here, R 11 represents an aryl group, a linear or branched alkyl group having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms), and R 12 It represents a hydrogen atom, and a linear or branched alkyl group having 1 to 6 carbon atoms (preferably a methyl group) which may be substituted 1 to 5 times by halogen (preferably substituted 1 to 3 times by fluorine or chlorine).

[0174] M n+ X n In the transition metal compound represented by FIG. 1 , n represents the formal charge on the metal and is an integer of 0 to 7.

[0175] As ligand compounds capable of coordinating and bonding with the transition metal of the transition metal compound, there can be listed: compounds having ligands containing one or more nitrogen atoms, oxygen atoms, phosphorus atoms or sulfur atoms that can coordinate with the transition metal via a σ bond, compounds having ligands containing two or more carbon atoms that can coordinate with the transition metal via a π bond, and compounds having ligands that can coordinate with the transition metal via a μ bond or an η bond.

[0176] The transition metal complex is not particularly limited. Preferred transition metal complexes include transition metal complexes of Group 7, Group 8, Group 9, Group 10, and Group 11. Further preferred transition metal complexes include complexes of 0-valent copper, 1-valent copper, 2-valent ruthenium, 2-valent iron, or 2-valent nickel.

[0177] As specific examples of catalysts that can be used in ATRP, when the central metal is copper, there can be listed: complexes of ligands with polyamines such as 2,2'-bipyridine and its derivatives, 1,10-phenoline and its derivatives, tetramethylethylenediamine, pentamethyldiethylenetriamine, and hexamethyltris(2-aminoethyl)amine. In addition, as divalent ruthenium complexes, there can be listed: dichlorotris(triphenylphosphine)ruthenium, dichlorotris(tributylphosphine)ruthenium, dichloro(cyclooctadiene)ruthenium, dichlorophenylruthenium, dichloro-p-isopropyltolueneruthenium, dichloro(norbornadiene)ruthenium, cis-dichlorobis(2,2'-bipyridine)ruthenium, dichlorotris(1,10-phenoline)ruthenium, carbonyl chloride hydride tris(triphenylphosphine)ruthenium, etc. Further, as divalent iron complexes, there can be listed bistriphenylphosphine complexes, triazacyclononane complexes, etc.

[0178] In the living radical polymerization, it is preferred to use a solvent.

[0179] Examples of the solvent used in the living radical polymerization include ester solvents such as ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; ether solvents such as diisopropyl ether, dimethoxyethane, and diethylene glycol dimethyl ether; halogen solvents such as dichloromethane and dichloroethane; aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, and isopropanol; and aprotic polar solvents such as dimethylformamide and dimethyl sulfoxide.

[0180] The above solvents may be used alone or in combination of two or more.

[0181] The polymerization temperature during the living radical polymerization is preferably in the range of room temperature to 120°C.

[0182] When the polymer of the present invention is produced by living radical polymerization, metal derived from the transition metal compound used in the polymerization may remain in the obtained polymer. The metal remaining in the obtained polymer can be removed using activated alumina or the like after the polymerization is completed.

[0183] [Lubricating oil composition]

[0184] The defoaming agent of the present invention can be preferably used as a defoaming agent for a lubricating oil composition. The lubricating oil composition of the present invention contains the defoaming agent of the present invention.

[0185] The defoaming agent of the present invention has high defoaming performance and can be used without limitation in lubricating oil compositions for drive system equipment such as automobile shock absorbers, transmissions, and power steering.

[0186] The content 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 ppm by mass, preferably 5 to 700 ppm by mass, and more preferably 10 to 400 ppm by mass, based on the total amount of the lubricating oil composition.

[0187] The lubricating oil base oil of the lubricating oil composition of the present invention may be a well-known composition, and may be a mineral oil, a synthetic oil, or a mixed oil of a mineral oil and a synthetic oil.

[0188] Examples of mineral oils include mineral oils obtained by subjecting atmospheric residual oil obtained by atmospheric distillation of crude oil to reduced pressure distillation to obtain a lubricating oil fraction, and subjecting the obtained lubricating oil fraction to one or more of solvent removal, solvent extraction, hydrogenation cracking, solvent dewaxing, contact dewaxing, hydrogenation refining, etc., and examples thereof include paraffin-based mineral oils and cycloparaffin-based mineral oils.

[0189] In addition, mineral oils produced by isomerizing mineral oil wax or wax produced by the Fischer-Tropsch process or the like (GTL wax) may also be mentioned.

[0190] Examples of the synthetic oil include polyolefins such as polybutene, α-olefin homopolymers or copolymers (eg, ethylene-α-olefin copolymers); various esters such as polyol esters, dibasic acid esters, and phosphoric acid esters; various ethers such as polyphenyl ethers; polyglycols, alkylbenzenes, and alkylnaphthalenes.

[0191] The lubricating base oil may be used alone or in combination of two or more.

[0192] The dynamic viscosity of the lubricating base oil at 100°C is preferably 2 mm 2 / s~20mm 2 / s, more preferably 2mm 2 / s~15mm 2 / s, and preferably 3mm 2 / s~10mm 2 / s range.

[0193] When the dynamic viscosity of the lubricating 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 it is easy to obtain the effect of improving the fuel consumption rate.

[0194] The lubricating base oil preferably has a paraffin content (sometimes described as %Cp) of 70% or more, more preferably 75% or more, and even more preferably 80% or more, as determined by ndM ring analysis.

[0195] When the paraffin content of the lubricating base oil is within the above range, oxidation stability and the like are improved.

[0196] The content of the lubricating base oil in the lubricating oil composition is, for example, in the range of 65 to 95 mass %, preferably 70 to 95 mass %, and more preferably 70 to 90 mass % of the total mass of the lubricating oil composition.

[0197] The lubricating oil composition of the present invention may contain the defoaming agent of the present invention and the lubricating base oil, and may further contain other additives.

[0198] As other additives, the material may contain ashless detergents, ashless friction modifiers, anti-wear agents, extreme pressure agents, viscosity index improvers, metal deactivators, pour point depressants, rust inhibitors, etc. These additives may be used alone or in combination of two or more.

[0199] The content of each other additive can be appropriately adjusted within a range not impairing the effects of the present invention, and is usually 0.001 to 25% by mass, preferably 0.005 to 20% by mass, and more preferably 0.01 to 15% by mass, based on the total amount of the lubricating oil composition.

[0200] The total content of 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.

[0201] Examples of the ashless detergent include alkenyl succinimides such as alkenyl succinic monoimide and alkenyl succinic diimide, and boron-modified alkenyl succinimides.

[0202] Examples of the ashless friction modifier include aliphatic amines, fatty acid esters, fatty acid amides, fatty acids, aliphatic alcohols, and aliphatic ethers having at least one alkyl or alkenyl group having 6 to 30 carbon atoms in the molecule.

[0203] Examples of anti-wear agents or extreme pressure agents include sulfur-containing compounds such as zinc dithiophosphate; phosphorus-containing compounds such as phosphites, phosphates, sulfonates, and amine salts or metal salts thereof; and sulfur- and phosphorus-containing anti-wear agents such as thiophosphites, thiophosphates, thiosulfonates, and amine salts or metal salts thereof.

[0204] Examples of the viscosity index improver include polymethacrylate, dispersed polymethacrylate, olefin copolymers (eg, ethylene-propylene copolymers), dispersed olefin copolymers, styrene copolymers (eg, styrene-diene copolymers, styrene-isoprene copolymers), and the like.

[0205] Examples of the metal deactivator include benzotriazole compounds, tolyltriazole compounds, imidazole compounds, and pyrimidine compounds.

[0206] Examples of the pour point depressant include ethylene-vinyl acetate copolymers, condensates of chlorinated paraffin and naphthalene, condensates of chlorinated paraffin and phenol, polymethacrylates, and polyalkylstyrene.

[0207] Examples of the rust inhibitor include petroleum sulfonates, alkylbenzene sulfonates, dinonylnaphthalene sulfonates, alkenyl succinates, and polyol esters.

[0208] The lubricating oil composition of the present invention is preferably used in a machine including an internal combustion engine or an electric motor to lubricate a drive portion of the machine.

[0209] The lubricating oil composition of the present invention can be used for any machine including an internal combustion engine or an electric motor, such as automobiles (gasoline automobiles, electric automobiles), robots (industrial robots, entertainment robots), aircraft (airplanes, helicopters), and various home electrical appliances.

[0210] Example

[0211] Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples.

[0212] In addition, the present invention is not limited to the following examples.

[0213] In Examples and Comparative Examples, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values ​​measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

[0214] The measurement conditions of GPC are as follows.

[0215] [GPC measurement conditions]

[0216] Measuring device: High-speed GPC device "HLC-8320GPC" manufactured by Tosoh Corporation

[0217] Column: "TSK GUARDCOLUMN SuperHZ-L" manufactured by Tosoh Corporation + "TSK gel SuperHZM-N" manufactured by Tosoh Corporation + "TSK gel SuperHZM-N" manufactured by Tosoh Corporation + "TSK gel SuperHZM-N" manufactured by Tosoh Corporation + "TSK gelSuperHZM-N" manufactured by Tosoh Corporation

[0218] Detector: RI (differential refractometer)

[0219] Data processing: "EcoSEC Data Analysis Version 1.07" manufactured by Tosoh Corporation

[0220] Column temperature: 40℃

[0221] Development solvent: tetrahydrofuran

[0222] Flow rate: 0.35mL / min

[0223] Measurement sample: 7.5 mg of a sample was dissolved in 10 ml of tetrahydrofuran, and the resulting solution was filtered through a millipore filter to prepare a measurement sample.

[0224] Sample injection volume: 20μL

[0225] Standard sample: According to the measurement manual of the above-mentioned "HLC-8320GPC", the following monodisperse polystyrene having a known molecular weight was used.

[0226] (monodisperse polystyrene)

[0227] "A-300" manufactured by TOSOH Co., Ltd.

[0228] "A-500" manufactured by TOSOH Co., Ltd.

[0229] "A-1000" manufactured by TOSOH Co., Ltd.

[0230] "A-2500" manufactured by TOSOH Co., Ltd.

[0231] "A-5000" manufactured by TOSOH Co., Ltd.

[0232] "F-1" manufactured by Tosoh Corporation

[0233] "F-2" manufactured by Tosoh Corporation

[0234] "F-4" manufactured by Tosoh Corporation

[0235] The F-10 manufactured by Tosoh Corporation

[0236] "F-20" manufactured by Tosoh Corporation

[0237] "F-40" manufactured by Tosoh Corporation

[0238] "F-80" manufactured by Tosoh Corporation

[0239] The F-128 manufactured by Tosoh Corporation

[0240] "F-288" manufactured by Tosoh Corporation

[0241] (Synthesis Example 1: Synthesis of Defoaming Agent (1))

[0242] In a glass flask including a stirrer, a thermometer, a cooling tube, and a dropping device, 30 parts by mass of 1,3-dimercapto-2-propanol, 215 parts by mass of 3-methacryloxypropyltris(trimethylsiloxy)silane, 200 parts by mass of methyl ethyl ketone, and 0.1 parts by mass of NaH were added. Next, stirring was started under a nitrogen atmosphere, the temperature in the flask was raised to 60°C, and stirring was performed for 1.5 hours to obtain a double-chain silicone monomer precursor (aa1) by the following synthesis route.

[0243] [Chemistry 8]

[0244]

[0245] In a glass flask including a stirring device, a thermometer, a cooling tube, and a dropping device, 17.6 parts by mass of a double-chain silicone monomer precursor (aa1), 20 parts by mass of n-butyl acetate, and 0.02 parts by mass of stannous octoate were added. Next, stirring was started under an air flow, the temperature in the flask was raised to 75°C, and 3 parts by mass of 2-isocyanatoethyl methacrylate was added dropwise over 15 minutes. After the addition was completed, the temperature was raised to 80°C and stirred for 1 hour to react. As a result, the disappearance of the absorption peak of the isocyanate group was confirmed by IR spectroscopy. Thus, a double-chain silicone monomer (a1) represented by the following formula was obtained.

[0246] [Chemistry 9]

[0247]

[0248] In a glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device, 52 parts by mass of n-butyl acetate as a solvent was placed, and the temperature was raised to 85° C. while stirring under a nitrogen stream. Next, 30 parts by mass of a double-chain silicone monomer (a1) and 20 parts by mass of methoxypolyethylene glycol methacrylate (the number of repetitions of ethylene oxide chains was about 9) dissolved in 50 parts by mass of n-butyl acetate, and a polymerization initiator solution prepared by dissolving 3 parts by mass of tert-butyl peroxy-2-ethylhexanoate as a free radical polymerization initiator in 15 parts by mass of n-butyl acetate were placed in different dropping devices, and the flask was kept at 85° C. and dripped for 2 hours. After the completion of the dripping, the mixture was stirred at 85° C. for 4 hours, then heated to 110° C. and stirred for another hour, thereby obtaining a defoaming agent (1) which is a polymer having a double-chain silicone monomer and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0249] The molecular weight of the obtained defoaming agent (1) was measured by GPC, and the weight average molecular weight (Mw) was 30,400.

[0250] (Synthesis Example 2: Synthesis of Defoaming Agent (2))

[0251] In a glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device, 52 parts by mass of n-butyl acetate as a solvent was placed, and the temperature was raised to 85° C. while stirring under a nitrogen stream. Next, two dropping liquids, 25 parts by mass of a double-chain silicone monomer (a1), 25 parts by mass of methoxypolyethylene glycol methacrylate (the number of repetitions of ethylene oxide chains was about 9) and 5 parts by mass of methyl methacrylate dissolved in 50 parts by mass of n-butyl acetate, and a polymerization initiator solution prepared by dissolving 3 parts by mass of tert-butyl peroxy-2-ethylhexanoate as a radical polymerization initiator in 15 parts by mass of n-butyl acetate, were placed in separate dropping devices, and the flask was kept at 85° C. and dropped over 2 hours. After completion of the dropwise addition, the mixture was stirred at 85°C for 4 hours, then heated to 110°C and stirred for further 1 hour to obtain a defoaming agent (2) comprising a double-chain silicone monomer and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0252] The molecular weight of the obtained defoaming agent (2) was measured by GPC, and the weight average molecular weight (Mw) was 71,700.

[0253] (Synthesis Example 3: Synthesis of Defoaming Agent (3))

[0254] In a glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device, 52 parts by mass of n-butyl acetate as a solvent was placed, and the temperature was raised to 85° C. while stirring under a nitrogen stream. Next, 20 parts by mass of a double-chain silicone monomer (a1), 4 parts by mass of trimethacryloxypropyltris(trimethylsiloxy)silane, 22 parts by mass of methoxypolyethylene glycol methacrylate (the number of repetitions of ethylene oxide chains was about 9), and 4 parts by mass of methyl methacrylate dissolved in 50 parts by mass of n-butyl acetate, and a polymerization initiator solution prepared by dissolving 3 parts by mass of tert-butyl peroxy-2-ethylhexanoate as a radical polymerization initiator in 15 parts by mass of n-butyl acetate were placed in separate dropping devices, and the mixture was dropped over 2 hours while the inside of the flask was kept at 85° C. After the completion of the dropwise addition, the mixture was stirred at 85°C for 4 hours, then heated to 110°C and stirred for another hour, thereby obtaining a defoaming agent (3), which is a polymer having a double-chain silicone monomer, 3-methacryloxypropyltris(trimethylsiloxy)silane, methyl methacrylate, and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0255] The molecular weight of the obtained defoaming agent (3) was measured by GPC, and the weight average molecular weight (Mw) was 50,700.

[0256] (Synthesis Example 4: Synthesis of Defoaming Agent (4))

[0257] In a glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device, 52 parts by mass of n-butyl acetate as a solvent was placed, and the temperature was raised to 95° C. while stirring under a nitrogen stream. Next, 39 parts by mass of a double-chain silicone monomer (a1), 8.5 parts by mass of trimethacryloxypropyl tris(trimethylsiloxy)silane, 45 parts by mass of methoxypolyethylene glycol acrylate (the number of repetitions of ethylene oxide chains was about 9), and 16.7 parts by mass of benzyl methacrylate dissolved in 133 parts by mass of n-butyl acetate, and two kinds of dropping liquids, a polymerization initiator solution prepared by dissolving 11 parts by mass of tert-butyl peroxy-2-ethylhexanoate as a radical polymerization initiator in 30 parts by mass of n-butyl acetate, were placed in separate dropping devices, and the flask was kept at 95° C. and dropped over 2 hours. After the completion of the dropwise addition, the mixture was stirred at 95°C for 3 hours, then heated to 110°C and stirred for another hour, thereby obtaining a defoaming agent (4), which is a polymer having a double-chain silicone monomer, 3-methacryloxypropyltris(trimethylsiloxy)silane, methyl methacrylate, and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0258] The molecular weight of the obtained defoaming agent (4) was measured by GPC, and the weight average molecular weight (Mw) was 27,000.

[0259] (Synthesis Example 5: Synthesis of Defoaming Agent (5))

[0260] In a glass flask including a stirring device, a thermometer, a cooling tube, and a dropping device, 50 parts by mass of a double-chain silicone monomer precursor (aa1), 22 parts by mass of n-heptane, and 10.5 parts by mass of triethylamine were added. Next, stirring was started under air flow, the temperature in the flask was raised to 40°C, and 5.2 parts by mass of acryloyl chloride was added dropwise over 15 minutes. After the addition was completed, the reaction was stirred for 3 hours, and then the excess acryloyl chloride was deactivated by adding water. Then, extraction was performed using citric acid to obtain a double-chain silicone monomer (a2) represented by the following formula.

[0261] [Chemistry 10]

[0262]

[0263] In a glass flask equipped with a stirrer, a thermometer, a cooling tube, and a dropping device, 52 parts by mass of n-butyl acetate as a solvent was placed, and the temperature was raised to 95° C. while stirring under a nitrogen stream. Next, two dropping liquids, 20 parts by mass of a double-chain silicone monomer (a2), 4 parts by mass of trimethacryloxypropyltris(trimethylsiloxy)silane, 22 parts by mass of methoxypolyethylene glycol methacrylate (the number of repetitions of ethylene oxide chains was about 9), and 4 parts by mass of methyl methacrylate dissolved in 50 parts by mass of n-butyl acetate, and a polymerization initiator solution prepared by dissolving 3 parts by mass of tert-butyl peroxy-2-ethylhexanoate as a radical polymerization initiator in 15 parts by mass of n-butyl acetate, were placed in separate dropping devices, and the mixture was dropped over 2 hours while the inside of the flask was kept at 95° C. After the completion of the dropwise addition, the mixture was stirred at 85°C for 4 hours, then heated to 110°C and stirred for another hour, thereby obtaining a defoaming agent (5), which is a polymer having a double-chain silicone monomer, 3-methacryloxypropyltris(trimethylsiloxy)silane, methyl methacrylate, and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0264] The molecular weight of the obtained defoaming agent (5) was measured by GPC, and the weight average molecular weight (Mw) was 17,000.

[0265] (Synthesis Example 6: Synthesis of Defoaming Agent (6))

[0266] In a glass flask including a stirring device, a thermometer, a cooling tube, and a dropping device, 200 parts by mass of a commercially available silicone compound represented by the following formula, 100 parts by mass of n-butyl acetate as a solvent, and 0.05 parts by mass of stannous octoate as a catalyst were added. Next, stirring was started under air flow, the temperature in the flask was raised to 75° C., 30 parts by mass of 2-isocyanate ethyl acrylate was added dropwise over 30 minutes, and after the addition was completed, the temperature was raised to 80° C. and stirred for 3 hours to carry out the reaction.

[0267] The obtained reaction product was subjected to IR spectrum measurement, and its structure was confirmed by the disappearance of the absorption peak of the isocyanate group. Thus, a single-chain silicone monomer represented by the following formula was obtained.

[0268] [Chemistry 11]

[0269]

[0270] (In the formula, n represents the number of repetitions, and the average value of n is 10)

[0271] In a glass flask including a stirring device, a thermometer, a cooling tube, and a dropping device, 7.5 parts by mass of 1,3-dimercapto-2-propanol, 138 parts by mass of the obtained single-chain silicone monomer, 100 parts by mass of n-butyl acetate, and 2.0 parts by mass of triethylamine were added. Next, stirring was started under a nitrogen environment, the temperature in the flask was raised to 80° C., and stirring was performed for 10 hours to obtain a double-chain silicone monomer precursor (aa3) through the following synthesis route.

[0272] [Chemistry 12]

[0273]

[0274] In a glass flask including a stirring device, a thermometer, a cooling tube, and a dropping device, 60 parts by mass of a double-chain silicone monomer precursor (aa3), 40 parts by mass of n-butyl acetate, and 0.02 parts by mass of stannous octoate are added. Next, stirring is started under an air flow, the temperature in the flask is raised to 75°C, and 4.1 parts by mass of 2-isocyanatoethyl methacrylate is added dropwise over 15 minutes. After the addition is completed, the temperature is raised to 80°C and stirred for 3 hours, and the reaction is carried out, and the disappearance of the absorption peak of the isocyanate group is confirmed by IR spectroscopy. Thus, a double-chain silicone monomer (a3) ​​represented by the following formula is obtained.

[0275] [Chemistry 13]

[0276]

[0277] In a glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device, 34 parts by mass of n-butyl acetate as a solvent was placed, and the temperature was raised to 85° C. while stirring under a nitrogen stream. Next, 13 parts by mass of a double-chain silicone monomer (a3) ​​dissolved in 33 parts by mass of n-butyl acetate, 15 parts by mass of methoxypolyethylene glycol methacrylate (the number of repetitions of ethylene oxide chains was about 9), 3 parts by mass of methyl methacrylate and 3 parts by mass of 3-methacryloxypropyltris(trimethylsiloxy)silane, and a polymerization initiator solution prepared by dissolving 2 parts by mass of tert-butyl peroxy-2-ethylhexanoate as a radical polymerization initiator in 10 parts by mass of n-butyl acetate were placed in separate dropping devices, and the mixture was dropped over 2 hours while the inside of the flask was kept at 85° C. After completion of the dropwise addition, the mixture was stirred at 85°C for 4 hours, then heated to 110°C and stirred for further 1 hour, thereby obtaining a defoaming agent (6) which is a polymer containing a double-chain silicone monomer and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0278] The molecular weight of the obtained defoaming agent (6) was measured by GPC, and the weight average molecular weight (Mw) was 25,000.

[0279] (Synthesis Example 7: Synthesis of Defoaming Agent (7))

[0280] In a glass flask equipped with a stirring device, a thermometer, a cooling tube, and a dropping device, 52 parts by mass of n-butyl acetate as a solvent was placed, and the temperature was raised to 90° C. while stirring under a nitrogen stream. Next, 20 parts by mass of a commercially available three-chain silicone compound (a4) represented by the following formula (Mw 570-620), 4 parts by mass of tri-methacryloxypropyl tris(trimethylsiloxy)silane, 22 parts by mass of methoxypolyethylene glycol methacrylate (the number of repetitions of ethylene oxide chains was about 9), and 4 parts by mass of methyl methacrylate, which were dissolved in 50 parts by mass of n-butyl acetate, and a polymerization initiator solution prepared by dissolving 5 parts by mass of tert-butyl peroxy-2-ethylhexanoate as a radical polymerization initiator in 15 parts by mass of n-butyl acetate were placed in separate dropping devices, and the mixture was dropped over 2 hours while the inside of the flask was kept at 90° C. After the completion of the dropwise addition, the mixture was stirred at 90°C for 2 hours, then heated to 110°C and stirred for further 1.5 hours, thereby obtaining a defoaming agent (7), which is a polymer having a tri-chain silicone monomer, 3-methacryloxypropyltris(trimethylsiloxy)silane, methyl methacrylate, and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0281] [Chemistry 14]

[0282]

[0283] The molecular weight of the obtained defoaming agent (7) was measured by GPC, and the weight average molecular weight (Mw) was 44,200.

[0284] (Comparative Synthesis Example 1: Synthesis of Defoaming Agent (1'))

[0285] A polymerization reaction was carried out in the same manner as in Synthesis Example 1, except that 20 parts by mass of 3-methacryloxypropyltris(trimethylsiloxy)silane represented by the following formula was used instead of the double-chain silicone monomer (a1), thereby obtaining a defoaming agent (1') which is a polymer having a single-chain silicone monomer and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0286] [Chemistry 15]

[0287]

[0288] The molecular weight of the obtained defoaming agent (1') was measured by GPC, and the weight average molecular weight (Mw) was 40,900.

[0289] (Comparative Synthesis Example 2: Synthesis of Defoaming Agent (2'))

[0290] A polymerization reaction was carried out in the same manner as in Synthesis Example 1 except that 20 parts by mass of a single-chain silicone monomer represented by the following formula was used instead of the double-chain silicone monomer (a1), thereby obtaining a defoaming agent (2') which is a polymer having a single-chain silicone monomer and a monomer having a group containing a polyoxyalkylene chain as polymerization components.

[0291] [Chemistry 16]

[0292]

[0293] (n represents the number of repetitions, and the average value of n is 10)

[0294] The molecular weight of the obtained defoaming agent (2') was measured by GPC, and the weight average molecular weight (Mw) was 24,500.

[0295] Separately, commercially available dimethyl silicone (“KF-96-60,000cs” manufactured by Shin-Etsu Silicone Co., Ltd.) shown below was prepared as a defoaming agent (3′).

[0296] [Chemistry 17]

[0297]

[0298] The defoaming agent produced as described above was used to carry out the following foaming test to evaluate the defoaming performance of the defoaming agent.

[0299] (Preparation of Lubricating Oil Composition)

[0300] To 100 parts by mass of a base lubricating oil having a lubricating base oil (paraffinic mineral oil) as a main component and containing a small amount of various additives (viscosity index improver, phosphite compound, thiadiazole compound, calcium detergent, metal deactivator, ashless dispersant, antioxidant, etc.), the defoaming agent shown in Table 1 was added in the amount shown in Table 1 using the diluting solvent shown in Table 1 to prepare lubricating oil compositions.

[0301] (Bubble Test)

[0302] The obtained lubricating oil composition was subjected to a foaming test at 80°C and 120°C according to the homogenizer method disclosed in Japanese Patent Laid-Open No. 2008-120880. Specifically, the lubricating oil composition was stirred under the following conditions using a homogenizer ("TK Labomix" manufactured by PRIMIX Co., Ltd.) equipped with an engine shaft ("Mini mixer" manufactured by PRIMIX Co., Ltd.), and the foaming amount (mL) was calculated by subtracting the reading (mL) of the oil surface before stirring from the reading (mL) of the foaming surface 3 seconds after the end of stirring. The smaller the foaming amount, the better the defoaming property.

[0303] [Foaming test measurement conditions]

[0304] Speed: 16,000rpm

[0305] Oil temperature: 80℃ and 120℃

[0306] Oil volume: 80ml

[0307] Container: 200ml measuring cylinder (inner diameter φ36mm)

[0308] Stirring time: 1 minute

[0309] [Table 1]

[0310]

[0311] The evaluation results in Table 1 show that the defoaming agent using a double-chain silicone monomer exhibits excellent defoaming properties even in a high temperature environment. On the other hand, it is known that the defoaming agent not using a double-chain silicone monomer (using a single-chain silicone monomer) cannot obtain sufficient defoaming properties in a high temperature environment.

Claims

1. A defoaming agent, which is a polymer having at least a polymerizable monomer (A) having two or more groups represented by the following general formula (a) as a polymer component, [Chemistry 1] (In the general formula (a), R 11 are independently an alkyl group having 1 to 6 carbon atoms, a phenyl group or -OSi(R 14 )3 represented by the group (R 14 are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group), R 12 are each independently an alkyl group having 1 to 6 carbon atoms or a phenyl group, R 13 is an alkyl group having 1 to 6 carbon atoms or a phenyl group, x represents the number of repetitions).

2. The defoaming agent according to claim 1, wherein the polymerizable monomer (A) is a compound represented by the following general formula (a-1): [Chemistry 2] (In the general formula (a-1), R 11 , R 12 , R 13 and x are respectively the same as R 11 , R 12 , R 13 and x are the same, R 15 is a hydrogen atom or a methyl group, L 11 and L 13 are independently a divalent organic group or a single bond, y is an integer in the range of 2 to 5, L 12 is an organic group having a valence of y+1).

3. The defoaming agent according to claim 1 or 2, wherein the polymer component comprises a polymerizable monomer (B), and the polymerizable monomer (B) has 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 comprising a polyoxyalkylene chain, and a group comprising a polyester chain.

4. The defoaming agent according to claim 3, wherein the polymerizable monomer (B) is one or more selected from the group consisting of a compound represented by the following general formula (b-1), a compound represented by the following general formula (b-2), a compound represented by the following general formula (b-3), and a compound represented by the following general formula (b-4), [Chemistry 3] (In the general formula (b-1), general formula (b-2), general formula (b-3), and general formula (b-4), R 21 is a hydrogen atom or a methyl group, R 22 is an alkyl group having 1 to 18 carbon atoms or a phenyl group, R 23 is a hydrogen atom or a methyl group, R 24 is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or a phenyl group, R 25 is a hydrogen atom or a methyl group, R 26 is an alkyl group having 1 to 18 carbon atoms, or an alkyl group having 1 to 18 carbon atoms and having an ether bond, R 27 is a hydrogen atom or a methyl group, R 28 is an alkyl group having 1 to 18 carbon atoms or an alkyl group having 1 to 18 carbon atoms and having an ether bond, L 2 is a divalent organic group or a single bond, n is an integer ranging from 1 to 4, m represents the number of repetitions, p is an integer in the range of 1 to 10, q represents the number of repetitions). 5 . The defoaming agent according to claim 1 , wherein the polymer component comprises a polymerizable monomer (C) having one group represented by the general formula (a).

6. The defoaming agent according to claim 5, wherein the polymerizable monomer (C) is a compound represented by the following general formula (c-1): [Chemistry 4] (In the general formula (c-1), R 11 , R 12 , R 13 and x are respectively the same as R 11 , R 12 , R 13 and x are the same, R 35 is a hydrogen atom or a methyl group, L 3 is a divalent organic group or a single bond). 7 . The defoaming agent according to claim 1 , wherein the ratio of the polymerizable monomer (A) in the total amount of the polymerizable components is in the range of 20% by mass to 80% by mass.

8. The defoaming agent according to claim 1 or 2, wherein the weight average molecular weight is in the range of 3,000 to 150,000.

9. A lubricating oil composition comprising a lubricating base oil and the defoaming agent according to claim 1 or 2.

10. The lubricating oil composition according to claim 9, which is used in a machine including an internal combustion engine or an electric motor to lubricate a drive part of the machine.

11. The lubricating oil composition according to claim 9, which is used in an automobile including an internal combustion engine or an electric motor for lubricating a driving part of the automobile.

12. A machine using the lubricating oil composition according to claim 9 in a driving part.

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