Defoaming agent and lubricating oil composition

Abstract

This antifoaming agent is obtained by polymerizing (A) at least one polymerizable monomer in (C) a solvent in which (B) at least one non-polymerizable polysiloxane is dissolved, wherein the component (A) contains less than 10 mass% of at least one monomer containing a Si atom with respect to the total amount of the component (A), or does not contain said at least one monomer.

Description

Technical Field

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

Background Art

[0002] In various mechanical devices, lubricating oil is used to improve the lubricity between members. Here, if the foaming of the lubricating oil deteriorates, there is a risk of causing lubrication failure, hydraulic control failure, reduction in cooling efficiency, etc., so the lubricating oil is required to suppress foaming.

[0003] For example, in automotive engines, transmissions, and axle units, in recent years, with the improvement of their performance and fuel efficiency, the conditions to which the lubricating oil is exposed have become more severe. When high-load operation and high-speed driving are continuously performed, foaming in engine oil, transmission oil, or axle unit oil increases. As a result, due to the entrainment of bubbles into the hydraulic flow path, hydraulic control failure occurs; foaming reduces lubrication performance and cooling efficiency; wear and seizure occur due to the rupture of the oil film at the friction point; and problems such as the promotion of the deterioration of the lubricating oil due to the increase in oil temperature occur. Therefore, engine oil, transmission oil, and axle unit oil that maintain high antifoaming properties are required so that foaming can be suppressed from the initial stage of operation over a long period.

[0004] Generally, lubricating oil contains a base oil and various additives added according to desired properties. Examples of additives include antifoaming agents for preventing foaming in lubricating oil. As antifoaming agents, polysiloxane-based antifoaming agents (silicone-based antifoaming agents) have been conventionally known. For example, in Patent Document 1, (a) polydimethylsiloxane having a kinematic viscosity at 25°C of 300,000 to 1,500,000 mm 2 / s, and (b) polydimethylsiloxane having a kinematic viscosity at 25°C of 500 to 9,000 mm 2There is described a lubricating oil composition containing a fluorinated polysiloxane of / s. Further, Patent Document 2 describes that a polydimethylsiloxane having a specific molecular weight distribution is blended in a lubricating oil in order to obtain an antifoaming effect against foams generated by high-speed stirring.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0006] Generally, an antifoaming agent exhibits antifoaming properties by being used in a finely dispersed state in a lubricating oil composition. However, in conventional lubricating oils containing a silicone-based antifoaming agent compound, sedimentation and uneven distribution of the silicone-based antifoaming agent tend to occur during long-term storage in a container or long-term use in a mechanical device, and the antifoaming property gradually disappears over time, resulting in a problem that the foaming of the lubricating oil deteriorates. For example, in a torque converter mounted on an automatic transmission or a pulley mounted on a metal belt continuously variable transmission, there are parts where a very large centrifugal force acts. When the lubricating oil is supplied to such parts, the silicone-based antifoaming agent compound used as the antifoaming agent is separated by the centrifugal force and accumulates at specific locations within the device, so that the concentration of the antifoaming agent in the lubricating oil circulating inside the device decreases, and the foaming of the lubricating oil deteriorates.

[0007] An object of the present invention is to provide an antifoaming agent capable of suppressing a decrease in antifoaming performance even during long-term storage and maintaining the antifoaming performance of a lubricating oil for a long period of time even in a lubricating environment where a high centrifugal force acts on the lubricating oil. Another object is to provide a lubricating oil composition containing the antifoaming agent.

Means for Solving the Problems

[0008] The present invention includes the following aspects [1] to

[10] . [1] An antifoaming agent obtained by polymerizing (A) one or more polymerizable monomers in a (C) solvent in which (B) one or more non-polymerizable polysiloxanes are dissolved, wherein the component (A) contains less than 10% by mass or does not contain one or more monomers containing a Si atom, based on the total amount of the component (A).

[0009] [2] The antifoaming agent according to [1], wherein the component (A) does not contain a monomer containing a Si atom.

[0010] [3] The antifoaming agent according to [1] or [2], wherein the component (A) contains one or more monomers represented by the following general formula (1).

[0011] [Chemical formula] (In general formula (1), Q 1 is a polymerizable functional group; Y 1 is a substituted or unsubstituted hydrocarbyl group having 1 to 40 carbon atoms; Z 1 is a linking group or a single bond that links Q 1 and Y 1 .)

[0012] [4] The defoaming agent according to any one of [1] to [3], wherein the component (A) contains one or more monomers selected from (meth)acrylate, α-olefin, and styrene.

[0013] [5] The defoaming agent according to any one of [1] to [4], wherein the component (A) further contains one or more polyfunctional monomers having two or more polymerizable functional groups in one molecule.

[0014] [6] The defoaming agent according to any one of [1] to [5], wherein the component (B) contains one or more polysiloxanes represented by the following general formula (2).

[0015] [Chemical formula] (In general formula (2), the order of the polysiloxane repeating units is arbitrary; R 1 and R 2 are each independently a non-polymerizable organic group having 1 to 18 carbon atoms and not containing a fluorine atom; R 3 and R 4 are each independently a non-polymerizable organic group containing a fluorine atom or a non-polymerizable organic group having 1 to 18 carbon atoms and not containing a fluorine atom, and at least one of R 3 and R 4 is a non-polymerizable organic group containing 3 or more fluorine atoms; R 5 , R 6 , R 7 , R 8 , R 9 , and R10 each independently represents a non-polymerizable organic group having 1 to 18 carbon atoms; n and m each independently represent an integer of 0 or greater; n+m is greater than or equal to 1; The ratio m / (n+m) is between 0 and 1.

[0016] [7] In the general formula (2), R 1 and R 2 each independently represents a saturated hydrocarbon group having 1 to 6 carbon atoms and containing no fluorine atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms and containing no fluorine atoms, which may have one or more alkyl substituents; R 3 and R 4 are each independently a non-polymerizable organic group containing a fluorine atom, a saturated hydrocarbon group containing 1 to 6 carbon atoms and not containing a fluorine atom, or an aromatic hydrocarbon group containing 6 to 10 carbon atoms and not containing a fluorine atom, which may have one or more alkyl substituents; R 3 and R 4 at least one of the groups is a non-polymerizable organic group containing three or more fluorine atoms; R 5 , R 6 , R 7 , R 8 , R 9 , and R 10 and each independently represent a saturated hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms and containing no fluorine atoms, which may have one or more alkyl substituents.

[0017] [8] In the general formula (2), R 1 and R 2 each independently represents a fluorine-free alkyl group having 1 to 3 carbon atoms or a phenyl group; R 3 and R 4 are each independently a non-polymerizable organic group containing a fluorine atom, an alkyl group having 1 to 3 carbon atoms and not containing a fluorine atom, or a phenyl group, and R 3 and R 4At least one of them is a non-polymerizable organic group containing three or more fluorine atoms; R 5 、R 6 、R 7 、R 8 、R 9 、and R 10 is each independently an alkyl group having 1 to 3 carbon atoms or a phenyl group, the defoaming agent according to [6] or [7].

[0018] [9] The defoaming agent according to any one of [1] to [8], wherein the weight average molecular weight of the component (B) is 5,000 to 500,000.

[0019]

[10] A lubricating oil base oil and [1] to [9] any one of the described defoaming agent and containing, a lubricating oil composition.

Effect of the Invention

[0020] The defoaming agent and the lubricating oil composition of the present invention can suppress a decrease in defoaming performance even during long-term storage, and can maintain the defoaming performance of the lubricating oil over a long period of time even in a lubricating environment where a high centrifugal action acts on the lubricating oil.

Brief Description of the Drawings

[0021]

Figure 1

Embodiments for Carrying Out the Invention

[0022] Hereinafter, the present invention will be described in detail. In this specification, unless otherwise specified, the notation "A to B" for numerical values A and B means "A or more and B or less". When a unit is attached only to the numerical value B in such notation, the said unit shall also be applicable to the numerical value A. Also, the words "or" and "or" mean logical sum unless otherwise specified. In this specification, the notation "E1 and / or E2" for elements E1 and E2 means "E1 or E2, or a combination thereof", and for elements E1, …, E N (where N is an integer of 3 or more) "E1, …, E N-1 , and / or E N " means "E1, …, E N-1 , or E N , or a combination thereof". Also, for an organic group, the notation "C i-j " (i and j are positive integers, i < j) means that the number of carbon atoms is i or more and j or less.

[0023] In this specification, "(meth) acrylate" means "acrylate and / or methacrylate", and "(meth) acrylic" means "acrylic and / or methacrylic".

[0024] <1. Antifoaming agent> The first aspect of the present invention is an antifoaming agent obtained by polymerizing (A) one or more polymerizable monomers (hereinafter sometimes simply referred to as "monomer" or "(A) component") in a (C) solvent (hereinafter sometimes referred to as "polymerization solvent") in which (B) one or more non-polymerizable polysiloxanes (hereinafter sometimes referred to as "coexisting polysiloxane" or "(B) component") are dissolved.

[0025] (Polymerization reaction) As the polymerization reaction, known polymerization reactions that are carried out in a solvent, such as radical polymerization, cationic polymerization, anionic polymerization, coordination polymerization, living radical polymerization, living cationic polymerization, living anionic polymerization, living coordination polymerization, etc., can be adopted. The polymerization reaction may be a chain polymerization or a living polymerization. Further, the chain polymerization may be an addition polymerization or a ring-opening polymerization. Among these, radical polymerization (which may be a living polymerization) or coordination polymerization (which may be a living polymerization) can be preferably adopted, and ordinary radical polymerization can be particularly preferably adopted. Examples of the reaction system for carrying out the polymerization reaction include dispersion polymerization, suspension polymerization, miniemulsion polymerization, microemulsion polymerization, emulsion polymerization, solution polymerization, etc. Among these, solution polymerization can be particularly preferably adopted.

[0026] ((A) monomer) As the component (A), one kind of monomer may be used alone, or two or more kinds of monomers may be used in combination. The component (A) preferably contains one or more kinds of monomers represented by the following general formula (1).

[0027] [Chemical formula] (In general formula (1), Q 1 is a polymerizable functional group; Y 1 is a substituted or unsubstituted hydrocarbyl group having 1 to 40 carbon atoms; Z 1 is a linking group or a single bond that links Q 1 and Y 1 .)

[0028] Q 1 As Q, a polymerizable functional group that causes a desired polymerization reaction can be adopted. Examples of Q 1 include groups having an ethylenically unsaturated bond such as a vinyl group and an isopropenyl group and causing an addition polymerization reaction, and groups causing a ring-opening polymerization reaction such as an epoxy group.

[0029] Y 1is a substituted or unsubstituted hydrocarbyl group having 1 to 40 carbon atoms. Examples of the unsubstituted hydrocarbyl group include an alkyl group (which may have a ring structure), an alkenyl group (the position of the double bond is arbitrary and it may have a ring structure), an aryl group (which may have an alkyl group or an alkenyl group), an arylalkyl group, an arylalkenyl group, and the like.

[0030] Examples of the alkyl group include various linear or branched alkyl groups. Examples of the ring structure that the alkyl group may have include cycloalkyl groups having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. When a chain hydrocarbon group is substituted on the ring structure, the substitution position on the ring structure is arbitrary.

[0031] Examples of the alkenyl group include various linear or branched alkenyl groups. Examples of the ring structure that the alkenyl group may have include, in addition to the above cycloalkyl groups, cycloalkenyl groups having 5 to 7 carbon atoms such as a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. When a chain hydrocarbon group is substituted on the ring structure, the substitution position on the ring structure is arbitrary.

[0032] Examples of the aryl group include, for example, a phenyl group, a naphthyl group, and the like. In addition, in an alkylaryl group, an alkenylaryl group, an arylalkyl group, and an arylalkenyl group, the substitution position on the aromatic ring is arbitrary.

[0033] Y in the form of an unsubstituted hydrocarbyl group 1 is preferably an aliphatic hydrocarbyl group, more preferably a chain aliphatic hydrocarbyl group, and even more preferably an alkyl group.

[0034] Y 1 may be an unsubstituted hydrocarbyl group, a substituted hydrocarbyl group, or a combination of an unsubstituted hydrocarbyl group and a substituted hydrocarbyl group. Y as a substituted hydrocarbyl group 1As one preferred form, one or more hydrogen atoms of an unsubstituted hydrocarbyl group (preferably an aliphatic hydrocarbyl group, more preferably a chain aliphatic hydrocarbyl group, particularly preferably an alkyl group. The same applies in the following paragraphs.) are substituted with a group having a heteroatom (preferably oxygen, nitrogen, sulfur, or a combination thereof); one or more methylene groups (-CH2- groups) of an unsubstituted hydrocarbyl group are substituted with an ether bond (-O- group), a secondary amino group (-NH- group), or a thioether bond (-S- group); one or more methine groups (>CH- groups) of an unsubstituted hydrocarbyl group are substituted with a tertiary amino group (>N- group); or a group obtained by a combination of these substitutions can be mentioned. Y in such a form 1 The number of heteroatoms contained in 1 is preferably 1 to 3. Y which is a substituted hydrocarbyl group 1 As other preferred forms of 1 , a polyether group, a fluoroalkyl group, a fluoroalkyl(poly)ether group, etc. can be mentioned.

[0035] Preferred examples of the group having a heteroatom that substitutes a hydrogen atom of a hydrocarbyl group include a hydroxy group; a mercapto group; a primary amino group; an amine residue having one or two nitrogen atoms and zero to two oxygen atoms such as a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, a benzoylamino group; a heterocyclic residue having one or two nitrogen atoms and zero to two oxygen atoms such as a morpholino group, a pyrrolyl group, a pyrrolinyl group, a pyridyl group, a methylpyridyl group, a pyrrolidinyl group, a piperidinyl group, a piperidino group, a quinolyl group, a pyrrolidonyl group, a pyrrolidono group, an imidazolinyl group, and a pyrazinyl group; a cyclic ether residue having 2 to 5 carbon atoms such as an epoxy group, an oxetanyl group, a tetrahydrofuranyl group, a tetrahydropyranyl group, etc.

[0036] Preferred examples of the polyether group can include a group represented by the following general formula (3).

[0037]

Chemical formula

[0038] Preferred examples of the fluoroalkyl group include a perfluoroalkyl group having 1 to 4 carbon atoms; a group represented by the following general formula (4); a group represented by the following general formula (5); 1,1,1,3,3,3 - hexafluoro - 2 - propyl group; 2,2 - bis(trifluoromethyl)propyl group; perfluorocyclohexylmethyl group; pentafluorobenzyl group; 2,3,5,6 - tetrafluorophenyl group; 2,2,2 - trifluoro - 1 - phenyl - 1 - (trifluoromethyl)ethyl group; 3 - (trifluoromethyl)benzyl group, and the like.

[0039]

Chemical formula

[0040] In general formula (4), from the viewpoint of facilitating avoidance of a decrease in defoaming property due to solidification of the polymer, q is preferably 8 or less, and in one embodiment, it can be 1 to 8.

[0041]

Chemical formula

[0042] In general formula (5), from the viewpoint of enhancing defoaming property, r is preferably 4 or more, and from the viewpoint of facilitating avoidance of a decrease in defoaming property due to solidification of the polymer, r is preferably 8 or less, and in one embodiment, it can be 4 to 8.

[0043] Examples of the perfluoroalkyl group having 1 to 4 carbon atoms include a trifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluoroisopropyl group, a perfluoro-tert-butyl group, and the like.

[0044] Examples of the group represented by the general formula (4) include a 2,2,2-trifluoroethyl group; a 3,3,3-trifluoropropyl group; a 1H,1H,3H-hexafluorobutyl group; a 2-(perfluorobutyl)ethyl group; a 3-(perfluorobutyl)propyl group; a 6-(perfluorobutyl)hexyl group; a 2-(perfluoro-5-methylhexyl)ethyl group; a 2-(perfluoro-7-methyloctyl)ethyl group; a 4,4,5,5,5-pentafluoropentyl group; a 2-(perfluorohexyl)ethyl group; a 2-(perfluorooctyl)ethyl group; a 3-(perfluorohexyl)propyl group; a 3-(perfluorooctyl)propyl group; a 1H,1H,3H-tetrafluoropropyl group; a 1H,1H,5H-octafluoropentyl group; a 1H,1H,7H-dodecafluoroheptyl group; a 1H,1H,9H-hexadecafluorononyl group; a 6-(perfluoro-1-methylethyl)hexyl group; a 1H,1H-(3,5,5-tris(trifluoromethyl))octafluorohexyl group; a 1H,1H,11H-eicosadecafluoroundecyl group; a 2-(perfluoro-3-methylbutyl)ethyl group; a 1H,1H-perfluoropropyl group; a 1H,1H-perfluorobutyl group; a 1H,1H-perfluoropentyl group; a 1H,1H-perfluorohexyl group; a 1H,1H-perfluoroheptyl group; a 1H,1H-perfluorooctyl group; a 1H,1H-perfluorononyl group; a 1H,1H-perfluorodecyl group; a 1H,1H-perfluoroundecyl group; a 1H,1H-perfluorododecyl group; a 1H,1H-perfluorotetradecyl group; a 1H,1H-perfluorohexadecyl group; a 1H,1H-perfluoro-3,7-dimethyloctyl group; a 2-(perfluorodecyl)ethyl group; a 2-(perfluorododecyl)ethyl group; a 2-(perfluoro-9-methyldecyl)ethyl group, and the like.

[0045] Examples of the group represented by the general formula (5) above include a 3-(perfluorobutyl)-2-hydroxypropyl group; a 3-(perfluoro-3-methylbutyl)-2-hydroxypropyl group; a 3-(perfluorooctyl)-2-hydroxypropyl group; a 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl group; a 3-(perfluoro-7-methyloctyl)-2-hydroxypropyl group, and the like.

[0046] Preferred examples of the fluoroalkyl(poly)ether group include a group represented by the following general formula (6); a 2-[(perfluoropropanoyl)oxy]ethyl group; and a fluoropolyether group having a perfluoropolyethylene oxide group, a perfluoropolypropylene oxide group, or a perfluoropolyoxetane group, and a copolymerized fluoropolyether group thereof, and the like.

[0047]

Chemical formula

[0048] Examples of the group represented by the general formula (6) above include a 1H,1H-perfluoro-3,6-dioxadecyl group; a 1H,1H-perfluoro-3,6,9-trioxadecyl group; a 1H,1H-perfluoro-3,6,9-trioxatridecyl group; a 2-perfluoropropoxy-2,3,3,3-tetrafluoropropyl group; a 1H,1H-perfluoro-2,5-dimethyl-3,6-dioxanonyl group, and the like.

[0049] As the substituted hydrocarbyl group having a fluorine atom, among those described above, the group represented by the general formula (4) can be particularly preferably employed.

[0050] Y 1The number of carbon atoms is from 1 to 40, and in one embodiment, it can be from 1 to 5, or from 6 to 18, or from 19 to 40, or from 19 to 36, or from 19 to 24.

[0051] Z 1 is Q 1 and Y 1 is a linking group or a single bond that links them. The linking group is not particularly limited as long as it can link Q 1 and Y 1 and. Examples of the linking group include -O-group, -S-group, >NH group, >NR' group (where R' is a C 1-40 hydrocarbyl group), -C(O)-group, -C(S)-group, -C(O)O-group, -C(O)S-group, -C(S)O-group, -C(S)S-group, -C(O)NH-group, -C(O)NR'-group (where R' is a C 1-40 hydrocarbyl group), -C(S)NH-group, -C(S)NR'-group (where R' is a C 1-40 hydrocarbyl group), -C(O)NHC(O)-group, -C(O)NR'C(O)-group (where R' is a C 1-40 hydrocarbyl group), -S(O)-group, -S(O)2-group, -S(O)2O-group, -P(O)(OH)O-group, -P(O)(OR')O-group (where R' is a C 1-40 hydrocarbyl group), -OPH(O)O-group (including tautomers), -OP(OR')O-group (where R' is a C 1-40 hydrocarbyl group), -OP(O)(OH)O-group, -OP(O)(OR')O-group (where R' is a C 1-40 hydrocarbyl group), etc. The number of carbon atoms of Z 1 (when having R', the number of carbon atoms including the carbon atoms of R') is 0 or more, preferably 0 to 6, more preferably 0 to 5, and in one embodiment, it can be 0 to 3.

[0052] In one embodiment, the component (A) preferably contains one or more monomers selected from (meth)acrylate esters, α-olefins, and styrene. In one embodiment, these monomers may correspond to the monomers represented by the above general formula (1). In the (meth)acrylate ester, Q 1is a vinyl group or a 1-methylvinyl group (isopropenyl group), and Y 1 is a substituted or unsubstituted hydrocarbyl group, and Z 1 is an ester bond. In α-olefin, Q 1 is a vinyl group, and Y 1 is an alkyl group, and Z 1 is a single bond. In styrene, Q 1 is a vinyl group, and Y 1 is a phenyl group, and Z 1 is a single bond.

[0053] (As the (meth)acrylic acid ester, for example, one or more (meth)acrylic acid esters selected from the (meth)acrylic acid ester represented by the following general formula (7) (hereinafter sometimes referred to as "(meth)acrylate monomer (M-1)"), the (meth)acrylic acid ester represented by the following general formula (8) (hereinafter sometimes referred to as "(meth)acrylate monomer (M-2)"), and the (meth)acrylic acid ester represented by the following general formula (9) (hereinafter sometimes referred to as "(meth)acrylate monomer (M-3)") can be used.)

[0054] [Chemical formula] (In general formula (7), R 13 represents a hydrogen atom or a methyl group, and R 14 represents a linear or branched hydrocarbon group having 1 to 5 carbon atoms, preferably an alkyl group.)

[0055] [Chemical formula] (In general formula (8), R 15 represents a hydrogen atom or a methyl group, and R 16 represents a linear or branched hydrocarbon group having 6 to 18 carbon atoms, preferably an alkyl group.)

[0056] [Chemical formula] (In general formula (9), R 17 represents a hydrogen atom or a methyl group, and R 18 represents a linear or branched hydrocarbon group having 19 or more carbon atoms, preferably an alkyl group.)

[0057] In the (meth)acrylate monomer (M-3) represented by general formula (9), R 18 is a linear or branched hydrocarbon group having 19 or more carbon atoms, and in one embodiment, it is a linear or branched hydrocarbon group having 19 to 50,000 carbon atoms, or a linear or branched hydrocarbon group having 19 to 500 carbon atoms, or a linear or branched hydrocarbon group having 19 to 100 carbon atoms, or a branched hydrocarbon group having 19 to 50 carbon atoms, or a branched hydrocarbon group having 19 to 40 carbon atoms. The hydrocarbon group is preferably an alkyl group.

[0058] In one embodiment, the component (A) may contain at least one (meth)acrylic acid ester. In one embodiment, the content of the (meth)acrylic acid ester in the component (A) is preferably 50% by mass or more, or 60% by mass or more, or 75% by mass or more, or 90% by mass or more, based on the total amount of the component (A), and may be 100% by mass.

[0059] In one embodiment, the component (A) may contain at least one (meth)acrylate monomer (M-2). In one embodiment, the content of the (meth)acrylate monomer (M-2) in the component (A) is preferably 50% by mass or more, or 60% by mass or more, or 75% by mass or more, or 90% by mass or more, based on the total amount of the component (A), and may be 100% by mass.

[0060] In one embodiment, the component (A) may contain the monomer (M-4) represented by the following general formula (10) (hereinafter sometimes referred to as "monomer (M-4)"), or the monomer (M-5) represented by the following general formula (11) (hereinafter sometimes referred to as "monomer (M-5)"), or a combination thereof. In one embodiment, the monomer (M-4) and / or (M-5) can be used in combination with one or more monomers selected from the above (meth)acrylate monomers (M-1) to (M-3).

[0061]

Chemical formula

[0062] Examples of the alkylene group having 1 to 18 carbon atoms represented by R 20 include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, and an octadecylene group (these alkylene groups may be linear or branched), and the like.

[0063] Examples of the group represented by E 1 include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidinol group, an acetylamino group, a benzoylamino group, a morpholino group, a pyrrolyl group, a pyrrolino group, a pyridyl group, a methylpyridyl group, a pyrrolidinyl group, a pyrrolidino group, a piperidinyl group, a piperidino group, a quinolyl group, a pyrrolidonyl group, a pyrrolidono group, an imidazolinyl group, and a pyrazinyl group, and the like.

[0064] [Chemical formula] (In general formula (11), R 21 represents a hydrogen atom or a methyl group, and E 2 represents an amine residue or a heterocyclic residue containing 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms.)

[0065] Examples of the group represented by E 2 include dimethylamino group, diethylamino group, dipropylamino group, dibutylamino group, anilino group, toluidino group, xylylidino group, acetylamino group, benzoylamino group, morpholino group, pyrrolyl group, pyrrolino group, pyridyl group, methylpyridyl group, pyrrolidinyl group, pyrrolidino group, piperidinyl group, piperidino group, quinolyl group, pyrrolidonyl group, pyrrolidono group, imidazolinyl group, and pyrazinyl group, etc.

[0066] Preferred examples of the monomers (M-4) and (M-5) include dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, morpholinomethyl methacrylate, morpholinoethyl methacrylate, N-vinylpyrrolidone, and mixtures thereof, etc.

[0067] In one embodiment, the total content of the monomers (M-4) and (M-5) in the component (A) may be preferably 25% by mass or less, or 15% by mass or less, or 10% by mass or less based on the total amount of the component (A).

[0068] As the α-olefin, for example, α-olefins having 3 to 18 carbon atoms can be preferably used. The carbon number of the α-olefin can be 3 to 12 in one embodiment.

[0069] Examples of other monomers that the component (A) may contain include ethylene, (meth)acrylonitrile, vinylpyridine, vinyl acetate, vinyl halide, maleic anhydride, fumaric acid diester, and the like.

[0070] Examples of other monomers represented by the general formula (1) include α-olefin epoxide and the like.

[0071] The content of the monomer containing an Si atom in the component (A) (when the component (A) contains two or more monomers containing an Si atom, the total content) is less than 10% by mass based on the total amount of the component (A), preferably less than 5% by mass, more preferably less than 3% by mass, and may be 0% by mass. Examples of the monomer containing an Si atom include the monomer represented by the general formula (1) in which Y 1 is a monomer containing a silyl substituent such as a trialkylsilyl group.

[0072] As the component (A), only one or more monomers having only one polymerizable functional group in one molecule (monofunctional monomers) may be used, or one or more monomers having two or more polymerizable functional groups in one molecule (polyfunctional monomers) and monofunctional monomers may be used in combination. By further including a polyfunctional monomer in addition to the monofunctional monomer in the component (A), it becomes possible to control the particle size of the obtained defoaming agent. Examples of the polyfunctional monomer include esters of (meth)acrylic acid and a saturated chain aliphatic polyhydric alcohol having 2 to 12 carbon atoms, a saturated alicyclic polyhydric alcohol having 5 to 12 carbon atoms, or an aromatic polyhydric alcohol having 6 to 12 carbon atoms, such as ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc.; di(meth)acrylate esters of poly(or oligo)alkylene glycol; divinylbenzene, and the like.

[0073] In one embodiment, the content of the monomer represented by the general formula (1) in the component (A) is preferably 50% by mass or more, or 60% by mass or more, or 75% by mass or more, or 90% by mass or more, based on the total amount of the component (A), and may be 100% by mass. In one embodiment, from the viewpoint of further suppressing the decrease in defoaming performance during storage and further enhancing the resistance to centrifugal force, the component (A) preferably contains one or more monomers represented by the general formula (1) in which Y 1 is an alkyl group having 6 to 40 carbon atoms, and the content thereof is preferably 50% by mass or more, or 60% by mass or more, or 75% by mass or more, or 90% by mass or more, based on the total amount of the component (A), and may be 100% by mass. In one embodiment, from the same viewpoint, the component (A) is represented by the general formula (1) and Y 1 is preferably an alkyl group having 8 to 40 carbon atoms, and the content thereof is preferably 50% by mass or more, or 60% by mass or more, or 75% by mass or more, or 90% by mass or more, based on the total amount of the component (A), and may be 100% by mass. In one embodiment, from the above-mentioned same viewpoints and the viewpoint of further enhancing defoaming properties, the component (A) is represented by the general formula (1) and Y 1 is preferably an alkyl group having 6 to 18 carbon atoms, and the content thereof is preferably 50% by mass or more, or 60% by mass or more, or 75% by mass or more, or 90% by mass or more, based on the total amount of the component (A), and may be 100% by mass. In one embodiment, from the same viewpoint, the component (A) is represented by the general formula (1) and Y 1 is preferably an alkyl group having 8 to 18 carbon atoms, and the content thereof is preferably 50% by mass or more, or 60% by mass or more, or 75% by mass or more, or 90% by mass or more, based on the total amount of the component (A), and may be 100% by mass. In one embodiment, the content of the polyfunctional monomer in the component (A) is preferably 0 to 50% by mass, or 0 to 40% by mass, or 0 to 25% by mass, or 0 to 10% by mass, based on the total amount of the component (A), and may be 0% by mass.

[0074] ((B) Coexisting polysiloxane) Component (B) is a non-polymerizable polysiloxane. Such polysiloxanes are commercially available as silicone defoamers or fluorosilicone defoamers. As component (B), a polysiloxane having a structure represented by the following general formula (2) can be used. Component (B) may be used alone as one kind of polysiloxane, or two or more kinds of polysiloxanes may be used in combination.

[0075] [Chemical formula] (In general formula (2), the order of the polysiloxane repeating units is arbitrary; R 1 and R 2 are each independently a non-polymerizable organic group having 1 to 18 carbon atoms and not containing a fluorine atom; R 3 and R 4 are each independently a non-polymerizable organic group containing a fluorine atom or a non-polymerizable organic group having 1 to 18 carbon atoms and not containing a fluorine atom, and at least one of R 3 and R 4 is a non-polymerizable organic group containing 3 or more fluorine atoms; R 5 、R 6 、R 7 、R 8 、R 9 、and R 10 are each independently a non-polymerizable organic group having 1 to 18 carbon atoms; n and m are each independently an integer of 0 or more; n + m is 1 or more; The ratio m / (n + m) is 0 to 1.)

[0076] In the general formula (2), examples of the non-polymerizable organic group having 1 to 18 carbon atoms include a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group, a fluoroalkyl group, and a polyether group, etc. Examples of the substituents in the substituted alkyl group and the substituted phenyl group include a hydroxy group, an amino group, an ether bond, an ester bond, etc. R 5 ~R 10 has 1 to 18 carbon atoms, and in one embodiment, it can be 1 to 12, and in another embodiment, it can be 1 to 6. Preferred examples of the organic group include a methyl group, a phenyl group, a fluoroalkyl group, etc. Among these, a methyl group or a fluoroalkyl group can be particularly preferably mentioned.

[0077] In the general formula (2), examples of the non-polymerizable organic group having 1 to 18 carbon atoms and not containing a fluorine atom include a substituted or unsubstituted alkyl group, a substituted or unsubstituted phenyl group, and a polyether group, etc. Examples of the substituents in the substituted alkyl group and the substituted phenyl group include a hydroxy group, an amino group, an ether bond, an ester bond, etc. The carbon number of the organic group is 1 to 18, in one embodiment, it is 1 to 12, and in another embodiment, it is 1 to 6. Preferred examples of the organic group include a methyl group, a phenyl group, etc. Among these, a methyl group can be particularly preferably adopted.

[0078] In the general formula (2), examples of the non-polymerizable organic group containing one or two fluorine atoms include a substituted alkyl group and a substituted phenyl group each having one or two fluoro groups. The carbon number of the non-polymerizable organic group containing one or two fluorine atoms is preferably 1 to 18, and in one embodiment, it can be 1 to 12, and in another embodiment, it can be 1 to 6.

[0079] In the general formula (2), as the organic group (fluorinated organic group) containing three or more fluorine atoms, a fluoroalkyl group or a fluoroalkyl(poly)ether group can be preferably adopted.

[0080] The number of fluorine atoms in the fluorinated organic group is preferably 3 or more from the viewpoint of enhancing the defoaming property, and preferably 17 or less from the viewpoint of facilitating avoidance of a decrease in the defoaming property due to solidification of the polymer.

[0081] As the fluoroalkyl group, the same groups as the fluoroalkyl groups described above for Y in the general formula (1) can be adopted, and the preferred embodiments are also the same as described above. Also, as the fluoroalkyl(poly)ether group, the same groups as the fluoroalkyl(poly)ether groups described above for Y in the general formula (1) can be adopted, and the preferred embodiments are also the same as described above. 1 in the general formula (1) can be adopted, and the preferred embodiments are also the same as described above. Also, as the fluoroalkyl(poly)ether group, the same groups as the fluoroalkyl(poly)ether groups described above for Y in the general formula (1) can be adopted, and the preferred embodiments are also the same as described above. 1 in the general formula (1) can be adopted, and the preferred embodiments are also the same as described above.

[0082] Among the fluorinated organic groups described above, the group represented by the general formula (4) can be particularly preferably adopted as the fluorinated organic group.

[0083] (Total number of all polysiloxane repeating units (-O-SiR 1 R 2 - repeating unit and -O-SiR 3 R 4 - repeating unit: see the general formula (2) above.) in the component (B) (Σ(n + m); where Σ means the sum for all polysiloxane structures in the component (B)), the ratio of the total number of polysiloxane repeating units containing fluorine atoms (-O-SiR 3 R 4 -) (Σm; where Σ means the sum for all polysiloxane structures in the component (B)) ((Σm) / Σ(n + m))) (hereinafter sometimes referred to as "average fluorination rate of the polysiloxane structure") is 0 to 1, and in one embodiment can be 0.01 to 1, or 0.05 to 1, or 0.10 to 1 from the viewpoint of further enhancing the defoaming property after shear. When the component (B) contains a combination of a plurality of polysiloxanes, it is preferable that the average fluorination rate of the polysiloxane structure for each of the plurality of polysiloxanes is within the above range.

[0084] In one embodiment, the weight average molecular weight of component (B) is preferably 5,000 or more, more preferably 10,000 or more, still more preferably 15,000 or more from the viewpoint of further enhancing the defoaming property. From the viewpoint of further improving the defoaming agent life by reducing the viscosity and enhancing the dispersibility, it is preferably 500,000 or less, more preferably 400,000 or less, still more preferably 300,000 or less. In one embodiment, it can be 5,000 to 500,000, or 10,000 to 400,000, or 15,000 to 300,000.

[0085] In this specification, the weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) using polystyrene as a standard substance. The measurement conditions of GPC are as follows. [GPC Measurement Conditions] Apparatus: ACQUITY (registered trademark) APC UV RI system manufactured by Waters Corporation Columns: In order from the upstream side, two ACQUITY (registered trademark) APC XT900A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation and one ACQUITY (registered trademark) APC XT200A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation are connected in series. Column temperature: 40 °C Sample solution: Tetrahydrofuran solution with a sample concentration of 1.0 mass% Eluent: Tetrahydrofuran Solution injection volume: 20.0 μL Detector: Differential refractive index detector Reference substance: 8-point standard polystyrene (Agilent EasiCal (registered trademark) PS-1 manufactured by Agilent Technologies) (molecular weights: 2698000, 597500, 290300, 133500, 70500, 30230, 9590, 2970) When the weight-average molecular weight measured based on the above conditions is less than 10,000, the column and the reference substance are changed to the following conditions and remeasurement is performed. Column: In order from the upstream side, one ACQUITY (registered trademark) APC XT125A (gel particle size 2.5 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation, and two ACQUITY (registered trademark) APC XT45A (gel particle size 1.7 μm, column size (inner diameter × length) 4.6 mm × 150 mm) manufactured by Waters Corporation are connected in series. Reference substance: 10 points of standard polystyrene (Agilent EasiCal (registered trademark) PS-1 manufactured by Agilent Technologies) (molecular weights: 30230, 9590, 2970, 890, 786, 682, 578, 474, 370, 266)

[0086] In one embodiment, the weight-average molecular weight of the component (B) is preferably M L1 (x) or more, more preferably M L2 (x) or more, still more preferably M L3 (x) or more. Also, from the viewpoint of further improving the antifoaming agent life by reducing the viscosity and enhancing the dispersibility, it is preferably M U1 (x) or less, more preferably M U2 (x) or less, still more preferably M U3 (x) or less. In one embodiment, M L1 (x) or more and M U1 (x) or less, or M L2 (x) or more and M U2 (x) or less, or M L3 (x) or more and M U3 (x) or less, and may be. However, x represents the average fluorination rate of the polysiloxane structure of the component (B), and M L1 (x), M L2 (x), M L3 (x), M U1 (x), M U2 (x), and M U3(x) is a function of x defined by the following mathematical expressions (1) to (6), respectively. When the (B) component contains a combination of a plurality of polysiloxanes, it is preferable that the weight average molecular weight of each of the plurality of polysiloxanes is within the above range corresponding to the average fluorination rate x of each polysiloxane.

[0087] [Number]

[0088] In one embodiment, the degree of polymerization of the polysiloxane structure of the (B) component ((n + m) in the above general formula (2)) is preferably 10 or more, more preferably 20 or more, and in one embodiment 30 or more, from the viewpoint of further enhancing the defoaming property. From the viewpoint of further improving the defoaming agent life by reducing the viscosity and enhancing the dispersibility, it is preferably 3,500 or less, and in one embodiment it can be 10 to 3,500, or 20 to 3,500, or 30 to 3,500. When the (B) component contains a combination of a plurality of polysiloxanes, it is preferable that the degree of polymerization of each of the plurality of polysiloxanes is within the above range.

[0089] In one embodiment, the degree of polymerization of the polysiloxane structure of the (B) component ((n + m) in the above general formula (2)) is preferably D L1 (x) or more, more preferably D L2 (x) or more, even more preferably D L3 (x) or more, and from the viewpoint of further improving the defoaming agent life by reducing the viscosity and enhancing the dispersibility, it is preferably D U1 (x) or less, more preferably D U2 (x) or less, even more preferably D U3 (x) or less, and in one embodiment D L1 (x) or more D U1 (x) or less, or D L2 (x) or more D U2 (x) or less, or D L3 (x) or more D U3(x) can be as follows. However, x represents the average fluorination rate of the polysiloxane structure of component (B), and D L1 (x), D L2 (x), D L3 (x), D U1 (x), D U2 (x), and D U3 (x) are each functions of x defined by the following formulas (7) to (12). When component (B) contains a combination of a plurality of polysiloxanes, it is preferable that the degree of polymerization of each of the plurality of polysiloxanes is within the above range corresponding to the average fluorination rate x of each polysiloxane.

[0090]

Number

[0091] ((C) Polymerization solvent) (C) component can be a solvent capable of dissolving (B) component and (A) component, and a solvent that does not interfere with the polymerization reaction of (A) component can be used. As the (C) component, one solvent can be used alone, or two or more solvents can be used in combination. Preferred examples of the polymerization solvent include aliphatic hydrocarbons (hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, etc.), aromatic hydrocarbons (benzene, toluene, xylene, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, etc.), esters (ethyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, isopropyl laurate, isopropyl palmitate, isopropyl myristate, etc.), ethers (diethyl ether, diisopropyl ether, tert-butyl methyl ether, dihexyl ether, dimethyl cellosolve, dioxane, etc.), halogenated hydrocarbons (carbon tetrachloride, chloroform, fluorosene (1,1,1-trifluoroethane), perchloroethylene, ethylene dichloride, dichloromethane, dichloroethane, trichloroethane, tetrachloroethane, chlorobenzene, dichlorobenzene, chlorofluoromethanes (as long as the number of chlorine atom substitutions and the number of fluorine atom substitutions are each 1 or more and the total is 4 or less, it is arbitrary), chlorofluoroethanes (as long as the number of chlorine atom substitutions and the number of fluorine atom substitutions are each 1 or more and the total is 6 or less, and the substitution positions of chlorine atoms and fluorine atoms are also arbitrary), etc.), aliphatic alcohols (butanol, 2-ethylhexanol, lauryl alcohol, etc.), mineral oil, etc. can be mentioned. For example, when the polymerization reaction of (A) component is radical polymerization (which may be living polymerization), among the above solvents, aliphatic ester solvents having 4 to 10 carbon atoms and aliphatic ketone solvents having 4 to 10 carbon atoms can be particularly preferably used as the polymerization solvent.

[0092] (Polymerization conditions) The concentration of component (A) in the reaction mixture at the start of polymerization (when using two or more monomers, it is the total concentration of all monomers) is preferably 1% by mass or more, more preferably 3% by mass or more, from the viewpoints of increasing the polymerization rate to increase the polymerization ratio and further enhancing the easy dispersibility of the resulting defoaming agent, based on the total mass of the reaction mixture (100% by mass). From the viewpoint of further enhancing the defoaming performance of the resulting defoaming agent, it is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, and in one embodiment, it can be 1 to 30% by mass, or 3 to 20% by mass, or 3 to 15% by mass.

[0093] The concentration of component (B) in the reaction mixture at the start of polymerization is preferably 10% by mass or more, more preferably 15% by mass or more, from the viewpoint of further enhancing the defoaming performance of the resulting defoaming agent, based on the total mass of the reaction mixture (100% by mass). From the viewpoint of further enhancing the easy dispersibility of the resulting defoaming agent, it is preferably 40% by mass or less, and in one embodiment, it can be 10 to 40% by mass, or 15 to 40% by mass.

[0094] In one embodiment, the amount of component (A) to be polymerized, as the number of parts by mass per 100 parts by mass of component (B), is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, from the viewpoint of further enhancing the easy dispersibility of the resulting defoaming agent. From the viewpoint of further enhancing the defoaming performance of the resulting defoaming agent, it is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, and in one embodiment, it can be 10 to 60 parts by mass, or 15 to 50 parts by mass.

[0095] In radical polymerization (for example, radical polymerization of a monomer having a polymerizable functional group containing an ethylenically unsaturated bond), a radical polymerization initiator soluble in the reaction solution at the polymerization temperature can be used without particular limitation. As the radical polymerization initiator, for example, known initiators such as organic peroxide-based and azo-based compounds can be used. The addition amount of the radical initiator is, from the viewpoint of increasing the polymerization conversion rate of the monomer, in parts by mass per 100 parts by mass of the component (A), preferably 0.1 part by mass or more, more preferably 1 part by mass or more, and from the viewpoint of suppressing a decrease in the defoaming property due to the radical initiator residue, preferably 10 parts by mass or less, and in one embodiment, it can be 0.1 to 10 parts by mass, or 1 to 10 parts by mass. In addition to the radical polymerization initiator, a chain transfer agent can also be further used. As the chain transfer agent, a chain transfer agent soluble in the reaction solution at the polymerization temperature, such as an alkyl mercaptan having 1 to 36 carbon atoms or an alkyl disulfide having 1 to 36 carbon atoms, can be used without particular limitation. The addition amount of the chain transfer agent is, from the viewpoint of suppressing the gelation of the defoaming agent polymer, in parts by mass per 100 parts by mass of the component (A), preferably 0.01 part by mass or more, more preferably 0.05 part by mass, and from the viewpoint of further improving the dispersion stability of the defoaming agent polymer, preferably 5 parts by mass or less, and in one embodiment, it can be 0.01 to 5 parts by mass, or 0.05 to 5 parts by mass.

[0096] As the catalyst in coordination polymerization (for example, coordination polymerization of a monomer having a polymerizable functional group containing an ethylenically unsaturated bond), metallocene or half-metallocene complexes of transition metals such as titanium, zirconium, hafnium, chromium, cobalt, nickel, iron, tantalum, rare earth elements (such as samarium, lanthanum, neodymium, ytterbium, lutetium, etc.); complexes of transition metals such as palladium and nickel having a diimine [N,N] ligand; complexes of transition metals such as titanium, zirconium, and nickel having a bidentate ([N - ,N - ) or tridentate ([N - ,N - ,O / N]) diamide ligand; phenoxy-imine [O -,N] ligands, complexes of transition metals such as titanium, zirconium, hafnium, vanadium, chromium, nickel; pyrrolid-imine [N - ,N] ligands, complexes of transition metals such as titanium, zirconium, hafnium; indolide-imine [N - ,N] ligands, complexes of transition metals such as titanium; imine-phenoxy [N,O - ligands, known homogeneous transition metal catalysts such as complexes of transition metals such as titanium and zirconium can be used. These catalysts are selected according to the monomer. These catalysts may be used in combination with one or more cocatalysts (for example, methylaluminoxane, trialkylaluminum (such as trimethylaluminum, triethylaluminum, triisobutylaluminum, etc.), dialkylaluminum halide (such as diethylaluminum chloride, etc.) and other aluminum compounds; boron compounds such as tris(perfluorophenyl)boron, trityltetrakis(perfluorophenyl)borate, etc.; dialkylzinc such as diethylzinc; magnesium halide such as magnesium chloride, etc.). The amount of the catalyst added can be appropriately selected by those skilled in the art according to the monomer and the catalyst system used, but it can be, for example, 0.1 to 10 parts by mass per 100 parts by mass of the component (A) to be polymerized.

[0097] In anionic polymerization (for example, anionic polymerization of a monomer having a polymerizable functional group containing a cyclic ether structure and / or a monomer having a polymerizable functional group containing an ethylenically unsaturated bond), known initiators (catalysts) such as organic alkali metal compounds (such as alkyl lithium compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, etc.), Grignard reagents, metal alkoxides, etc. can be used. The amount of the initiator (catalyst) added can be, for example, 0.1 to 10 parts by mass per 100 parts by mass of the component (A).

[0098] In cationic polymerization (for example, cationic polymerization of a monomer having a polymerizable functional group containing a cyclic ether structure and / or a monomer having a polymerizable functional group containing an ethylenically unsaturated bond), for example, metal halides (such as halides of aluminum, tin, iron, titanium, gallium, indium, zinc, zirconium, hafnium, bismuth, silicon, germanium, antimony, molybdenum, niobium, etc.), phosphorus pentafluoride, boron trihalide, tris(perfluorophenyl)boron, dialkylaluminum halide, alkylaluminum dihalide and other Lewis acids; known catalysts (initiators) such as trialkylaluminum can be used. These catalysts may be used in combination with additives (promoters, initiating species, added salts, or added bases) such as water, alcohol, acid chloride, alkyl halide, tetraalkylammonium salt, tetraalkylphosphonium salt, base (such as ester, ether, amine, sulfide, N,N-dimethylacetamide, etc.). The addition amount of the catalyst (initiator) can be, for example, 0.1 to 10 parts by mass per 100 parts by mass of the component (A).

[0099] The reaction temperature in the polymerization can be appropriately selected by those skilled in the art according to the monomer composition of the component (A), the polymerization reaction, the presence or absence of an initiator and catalyst, the type of catalyst, and the concentrations of the component (A) and the component (B).

[0100] In the defoaming agent of the present invention, as a result of polymerizing the monomer (A) in a solution in which the polysiloxane (B) is dissolved, the easy microdispersibility of the defoaming agent is enhanced. Therefore, even if the defoaming agent is blended into the lubricating oil composition in the same manner as a conventional defoaming agent, a state in which the defoaming agent is finely dispersed in the lubricating oil composition can be easily achieved. Furthermore, even after a long time has passed or after a strong centrifugal action has been applied, the state in which the defoaming agent is finely dispersed in the lubricating oil composition is maintained. Therefore, when the defoaming agent is blended into the lubricating oil composition, a decrease in defoaming performance due to separation and sedimentation of the defoaming agent can be suppressed.

[0101] The easy dispersibility of the defoaming agent obtained by polymerization can be evaluated by the average particle diameter of the defoaming agent particles in the dispersion containing the defoaming agent. 1 mL of the solution containing the defoaming agent after polymerization is added to 10 mL of mineral oil, and the defoaming agent is finely dispersed by sufficiently stirring. The average particle diameter of the defoaming agent particles (the average particle diameter determined by cumulant analysis using the dynamic light scattering method) in the dispersion (25 °C) is preferably 10 μm or less, more preferably 5 μm or less, still more preferably 2 μm or less, from the viewpoints of further suppressing the separation and sedimentation of the defoaming agent and enhancing the defoaming property, and in one embodiment, it can be 0.05 to 10 μm, or 0.1 to 5 μm, or 0.1 to 2 μm. In measuring the average particle diameter, as the above-mentioned mineral oil, for example, YUBASE (registered trademark) 4 manufactured by SK Lubricants Co., Ltd. (kinematic viscosity (100 °C): 4.2 mm 2 / s, kinematic viscosity (40 °C): 19.4 mm 2 / s, viscosity index: 125) can be preferably used. As the conditions for the above-mentioned stirring, for example, in a 100 mL beaker, using a cylindrical PTFE magnetic stirrer with a diameter of 8 mm and a length of 30 mm, the conditions of stirring at a rotation speed of 200 rpm for 30 minutes at room temperature can be preferably adopted. In measuring the average particle diameter by the dynamic light scattering method, for example, a dynamic light scattering method measuring device Photal ELSZ-2000S (manufactured by Otsuka Electronics Co., Ltd.) can be preferably used. According to the defoaming agent of the present invention, it is easy to obtain a dispersion in which the average particle diameter of the defoaming agent particles is 10 μm or less, and no special operation other than stirring is required to obtain such a dispersion.

[0102] <2. Lubricating oil composition> The second aspect of the present invention is a lubricating oil composition containing a lubricating base oil and the defoaming agent according to the first aspect of the present invention. The defoaming agent according to the first aspect of the present invention may be used alone or in combination of two or more.

[0103] (Lubricating base oil) The lubricating base oil in the lubricating oil composition of the present invention is not particularly limited, and mineral oil-based oils and synthetic oil-based oils used in ordinary lubricating oils can be used.

[0104] Examples of mineral oil base oils include those 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 deasphalting, solvent extraction, hydrocracking, solvent dewaxing, and hydrorefining, or lubricating oil base oils produced by a method of isomerizing GTL WAX (gas-to-liquid wax) produced by a wax isomerization process, a Fischer-Tropsch process, or the like.

[0105] Examples of synthetic base oils include poly-α-olefins such as 1-octene oligomer and 1-decene oligomer or their hydrogenated products, isobutene oligomer or its hydrogenated product, paraffin, diesters (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, etc.), polyol esters (trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, etc.), polyoxyalkylene glycols, dialkyldiphenyl ethers, polyphenyl ethers, etc. Other examples of synthetic base oils include aromatic synthetic oils such as alkylnaphthalene, alkylbenzene, and aromatic esters, or mixtures thereof.

[0106] In the lubricating oil composition of the present invention, as the lubricating oil base oil, a mineral oil base oil, a synthetic base oil, or an arbitrary mixture of two or more lubricating oils selected therefrom can be used. For example, one or more mineral oil base oils, one or more synthetic base oils, a mixed oil of one or more mineral oil base oils and one or more synthetic base oils, etc. can be mentioned.

[0107] The kinematic viscosity of the base oil (total base oil) at 40 °C is preferably 1.0 to 100 mm 2 / s. If the kinematic viscosity of the base oil is too high, the low-temperature viscosity tends to deteriorate, and conversely, if it is too low, the wear resistance at the sliding parts of various devices decreases. From the viewpoint of preventing the viscosity reduction of the obtained lubricating oil composition, the kinematic viscosity of the base oil (total base oil) at 40 °C is 1.0 to 50 mm 2It is preferably from 1.0 to 25 mm / s, and particularly preferably from 1.0 to 25 mm / s. 2 It is particularly preferably from 1.0 to 25 mm / s.

[0108] The pour point of the base oil (total base oil) is not particularly limited, but is preferably -10°C or lower, and particularly preferably -15°C or lower.

[0109] When the kinematic viscosity of the base oil (total base oil) at 100°C is 2 mm 2 / s or more, its viscosity index is preferably 105 or more from the viewpoint of preventing a decrease in viscosity at high temperatures.

[0110] The content of the base oil (total base oil) in the lubricating oil composition can be, for example, 80 to 99% by mass, or 85 to 99% by mass based on the total amount of the composition.

[0111] (Antifoaming agent) The antifoaming agent according to the first aspect of the present invention has already been described in detail. The content of the antifoaming agent according to the first aspect of the present invention in the lubricating oil composition (in the case of a combination of two or more, the total content) is preferably 1 mass ppm or more, more preferably 5 mass ppm or more, from the viewpoint of further enhancing the antifoaming performance, as the amount of silicon based on the total amount of the composition. Also, from the viewpoint of further suppressing the sedimentation of the antifoaming agent and further enhancing the antifoaming agent life, it is preferably 100 mass ppm or less, more preferably 50 mass ppm or less, and can be 1 to 100 mass ppm, or 5 to 50 mass ppm in one embodiment. In this specification, the content of silicon in the oil is measured by inductively coupled plasma optical emission spectrometry (intensity ratio method (internal standard method)) in accordance with JIS K0116.

[0112] (Other additives) In addition to the above lubricating oil base oil and the antifoaming agent according to the first aspect of the present invention, the lubricating oil composition of the present invention may further contain one or more additives selected from ashless dispersants, antioxidants, friction modifiers, antiwear agents or extreme pressure agents, metal detergents, viscosity index improvers or pour point depressants, corrosion inhibitors, rust preventives, metal deactivators, demulsifiers, antifoaming agents other than the antifoaming agent according to the first aspect of the present invention, and colorants. Note that an additive package may be obtained by adding one or more additives selected from these to the antifoaming agent according to the first aspect of the present invention.

[0113] As the ashless dispersant, for example, known ashless dispersants such as succinimide-based ashless dispersants can be used. Examples include polybutenyl succinimide having a polybutenyl group with a number average molecular weight of 900 to 3,500 or less, polybutenyl benzylamine, polybutenylamine, and derivatives thereof (such as boric acid-modified products, etc.). When the lubricating oil composition of the present invention contains an ashless dispersant, its content is usually 0.01% by mass or more, preferably 0.1% by mass or more, based on the total amount of the lubricating oil composition, that is, assuming the total amount of the lubricating oil composition is 100% by mass. Also, it is usually 20% by mass or less, preferably 10% by mass or less.

[0114] As the antioxidant, known antioxidants such as phenolic antioxidants and amine-based antioxidants can be used. Examples include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated-α-naphthylamine, and phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol and 4,4'-methylenebis(2,6-di-t-butylphenol). When the lubricating oil composition of the present invention contains an antioxidant, its content is usually 5.0% by mass or less, preferably 3.0% by mass or less, based on the total amount of the lubricating oil composition. Also, it is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more.

[0115] As the friction modifier, known friction modifiers can be used. Examples include fatty acid esters; fatty acid amides; phosphorus compounds such as phosphoric acid esters, phosphorous acid esters, and thiophosphoric acid esters; organic molybdenum compounds such as MoDTP and MoDTC; organic zinc compounds such as ZnDTP; organic boron compounds such as alkyl mercapto borate; graphite; molybdenum disulfide; antimony sulfide; boron compounds; polytetrafluoroethylene and the like. When the lubricating oil composition of the present invention contains a friction modifier, its content is usually 0.05 to 5% by mass based on the total amount of the lubricating oil composition.

[0116] As the antiwear agent or extreme pressure agent, known antiwear agents or extreme pressure agents can be used. Examples include metal dithiophosphates (Zn salts, Pb salts, Sb salts, Mo salts, etc.), metal dithiocarbamates (Zn salts, Pb salts, Sb salts, Mo salts, etc.), naphthenic acid metal salts (Pb salts, etc.), fatty acid metal salts (Pb salts, etc.), boron compounds, phosphoric acid esters, phosphorous acid esters, alkyl hydrogen phosphites, phosphoric acid ester amine salts, phosphoric acid ester metal salts (Zn salts, etc.), disulfides, sulfurized oils and fats, sulfurized olefins, dialkyl polysulfides, diaryl alkyl polysulfides, diaryl polysulfides and the like. When the lubricating oil composition of the present invention contains an antiwear agent or an extreme pressure agent, its content is usually 0.05 to 5% by mass based on the total amount of the lubricating oil composition.

[0117] As the metal detergent, known metal detergents can be used. Examples include alkali metal sulfonates, alkaline earth metal sulfonates, alkali metal phenates, alkaline earth metal phenates, alkali metal salicylates, alkaline earth metal salicylates, and combinations thereof. These metal detergents may be overbased. In this specification, "alkaline earth metal" includes Mg. When a metal detergent is contained in the lubricating oil composition of the present invention, its content is not particularly limited. However, in the case of an automotive transmission, it is usually 0.005 to 1.0% by mass in terms of the amount of metal element based on the total amount of the lubricating oil composition. In the case of an internal combustion engine, it is usually 0.01 to 5.0% by mass in terms of the amount of metal element based on the total amount of the lubricating oil composition. In the case of an automotive transaxle unit, it is usually 0.001 to 0.1% by mass in terms of the amount of metal element based on the total amount of the lubricating oil composition.

[0118] As the viscosity index improver or pour point depressant, known viscosity index improvers or pour point depressants can be used. Examples of the viscosity index improver include polymers, copolymers of one or more monomers selected from various methacrylic acid esters, and hydrogenated products thereof, so-called non-dispersant viscosity index improvers; so-called dispersant viscosity index improvers obtained by copolymerizing various methacrylic acid esters containing nitrogen compounds; non-dispersant or dispersant ethylene-α-olefin copolymers and hydrogenated products thereof; polyisobutylene and hydrogenated products thereof; hydrogenated products of styrene-diene copolymers; styrene-maleic anhydride ester copolymers; and polyalkylstyrenes, etc. When the lubricating oil composition of the present invention contains a viscosity index improver or pour point hardener, its content is usually 0.1 to 20% by mass based on the total amount of the lubricating oil composition. Examples of the pour point depressant include polymethacrylate-based polymers, etc. When the lubricating oil composition of the present invention contains a pour point depressant, its content is usually 0.01 to 2% by mass based on the total amount of the lubricating oil composition. It should be noted that the defoaming agent according to the first aspect of the present invention is obtained by polymerizing a monomer in a solution in which a non-polymerizable polysiloxane is dissolved, but the present inventors have confirmed that the polysiloxane cannot be separated from the defoaming agent after polymerization, and that a polymer not containing polysiloxane cannot be separated from the defoaming agent after polymerization.

[0119] As corrosion inhibitors, known corrosion inhibitors such as benzotriazole-based compounds, tolyltriazole-based compounds, thiadiazole-based compounds, and imidazole-based compounds can be used. When the lubricating oil composition of the present invention contains a corrosion inhibitor, its content is usually 0.005 to 5% by mass based on the total amount of the lubricating oil composition.

[0120] As rust inhibitors, known rust inhibitors such as petroleum sulfonates, alkylbenzene sulfonates, dinonylnaphthalene sulfonates, alkyl sulfonates, fatty acids, alkenyl succinic acid half esters, fatty acid soaps, polyhydric alcohol fatty acid esters, fatty acid amines, oxidized paraffins, and alkyl polyoxyethylene ethers can be used. When the lubricating oil composition of the present invention contains a rust inhibitor, its content is usually 0.005 to 5% by mass based on the total amount of the lubricating oil composition.

[0121] As metal deactivators, known metal deactivators such as imidazoline, pyrimidine derivatives, alkyl thiadiazole, mercaptobenzothiazole, benzotriazole and its derivatives, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bisdialkyldithiocarbamate, 2-(alkyldithio)benzimidazole, and β-(o-carboxybenzylthio)propionitrile can be used. When these metal deactivators are contained in the lubricating oil composition of the present invention, their content is usually 0.005 to 1% by mass based on the total amount of the lubricating oil composition.

[0122] As demulsifiers, known demulsifiers such as polyalkylene glycol-based nonionic surfactants can be used. When the lubricating oil composition of the present invention contains a demulsifier, its content is usually 0.005 to 5% by mass based on the total amount of the lubricating oil composition.

[0123] As defoamers other than the defoamer according to the first aspect described above, for example, known defoamers such as silicone, fluorosilicone, and fluoroalkyl ether can be used. When these defoamers are contained in the lubricating oil composition of the present invention, the content thereof is usually 0.0001 to 0.1% by mass based on the total amount of the lubricating oil composition.

[0124] As the colorant, for example, known colorants such as azo compounds can be used.

[0125] (Lubricating oil composition) The viscosity of the lubricating oil composition of the present invention is not particularly limited. However, the defoamer according to the first aspect of the present invention generally has a kinematic viscosity at 40 ° C of 2 mm 2 / s or more and 50 mm 2 / s or less, and can be preferably used in a lubricating oil composition, and is particularly effective in a relatively low-viscosity lubricating oil composition having a kinematic viscosity at 40 ° C of 2 mm 2 / s or more and 25 mm 2 / s or less.

[0126] In the lubricating oil composition of the present invention, since the storage stability of the defoamer is improved, separation and sedimentation of the defoamer can be suppressed even during long-term storage, thereby suppressing a decrease in defoaming performance. Further, the lubricating oil composition of the present invention can maintain good defoaming performance for a long period of time even in a lubricating environment where a high centrifugal action acts on the lubricating oil. As a result, foaming of the lubricating oil can be suppressed over a long period of time, so that promotion of deterioration of the lubricating oil due to foaming, poor hydraulic control, wear, seizure, etc. can also be suppressed over a long period of time.

[0127] (Use) From the perspective of the above-described effects, the lubricating oil composition of the present invention can be widely used in lubricating applications where defoaming performance is required. For example, it can be preferably used as engine oil for internal combustion engines, hydraulic oils, industrial gear oils, turbine oils, compressor oils, transmission oils, automotive axle unit oils, etc. Among them, it can be particularly preferably used as automotive engine oil, transmission oil for automobiles (which may be electric vehicles), or automotive axle unit oil.

[0128] (Manufacture) When blending the defoaming agent according to the first aspect of the present invention into the lubricating oil composition, a known method can be adopted. For example, a solution containing the defoaming agent according to the first aspect of the present invention obtained by polymerization is added to a diluting solvent and stirred to prepare a diluted solution in which the defoaming agent is finely dispersed, and the diluted solution is added to a lubricating oil composed of a base oil or a lubricating oil containing the base oil and one or more additives other than the defoaming agent, whereby a lubricating oil composition containing the defoaming agent according to the first aspect of the present invention can be prepared. Also, for example, a solution containing the defoaming agent according to the first aspect of the present invention is dissolved in a base oil and a diluting solvent (for example, a hydrocarbon-based solvent) capable of dissolving the defoaming agent to prepare a diluted solution in which the defoaming agent is dissolved, and the diluted solution is added to and stirred in a lubricating oil composed of a base oil or a lubricating oil containing the base oil and one or more additives other than the defoaming agent to finely disperse the defoaming agent in the lubricating oil, whereby a lubricating oil composition containing the defoaming agent according to the first aspect of the present invention can also be prepared. As the diluting solvent, a solvent that is soluble in the base oil and capable of dissolving or finely dispersing the defoaming agent can be preferably used, and the base oil can also be used as the diluting solvent.

[0129] The concentration of the defoaming agent in the diluent is preferably 500 mass ppm or more, more preferably 1,000 mass ppm or more, still more preferably 2,000 mass ppm or more, in terms of the amount of silicon based on the total amount of the diluent, from the viewpoint of reducing the influence of the diluent on the flash point of the lubricating oil. Also, from the viewpoint of further suppressing the sedimentation of the defoaming agent and further increasing the defoaming agent life, it is preferably 50,000 mass ppm or less, more preferably 40,000 mass ppm or less. In one embodiment, it can be 500 to 50,000 mass ppm, or 1,000 to 50,000 mass ppm, or 2,000 to 40,000 mass ppm.

[0130] The amount of the diluent added to the lubricating oil can be an amount that realizes the preferred concentration of the defoaming agent in the lubricating oil composition described above.

[0131] Before the diluent is added to the lubricating oil, in addition to the base oil, other additives other than the defoaming agent may already be contained. Also, after adding the diluent to a lubricating oil composed of a base oil that does not contain additives other than the defoaming agent, other additives may be added.

[0132] When adding the diluent to the lubricating oil, the diluent may be added sequentially little by little (for example, dropped) to the lubricating oil while mixing, or the desired amount of the diluent may be added to the lubricating oil at once. However, from the viewpoint of facilitating more fine dispersion of the defoaming agent in the lubricating oil or from the viewpoint of enhancing the uniformity of the defoaming agent concentration in the lubricating oil composition, it is preferable to mix while adding the diluent sequentially.

Examples

[0133] Hereinafter, the present invention will be described more specifically based on Examples and Comparative Examples. Note that the following Examples are intended to illustrate the present invention and are not intended to limit the present invention.

[0134] <Production Examples 1 to 14> (Measurement of average particle diameter of defoaming agent) In the following production examples, the average particle diameter of the antifoaming agent obtained by polymerization was calculated by cumulant analysis based on the results measured using a dynamic light scattering measurement device Photal ELSZ-0 (manufactured by Otsuka Electronics Co., Ltd.) for a sample (25 °C) in which 1 mL of the solution containing the antifoaming agent after polymerization was added to 10 mL of mineral oil and the antifoaming agent was finely dispersed by sufficiently stirring. As the above mineral oil, YUBASE (registered trademark) 4 manufactured by SK Lubricants Co., Ltd. (kinematic viscosity (100 °C): 4.2 mm 2 / s, kinematic viscosity (40 °C): 19.4 mm 2 / s, viscosity index: 125) was used. Also, in the above stirring, in a 100 mL beaker, using a cylindrical PTFE (polytetrafluoroethylene) magnetic stirrer with a diameter of 8 mm and a length of 30 mm, it was stirred at a rotation speed of 200 rpm for 30 minutes at room temperature.

[0135] (Production Example 1) The antifoaming agent A was produced by solution polymerization according to the following procedure. Into a 100 mL four-necked flask equipped with a polytetrafluoroethylene stirring blade (with a vacuum seal), Dimroth condenser, three-way cock for nitrogen introduction, and sample inlet, 30 parts by mass of diisobutyl ketone as a polymerization solvent, 1.8 parts by mass of stearyl methacrylate as a monomer, and 0.2 parts by mass of EGDMA (ethylene glycol dimethacrylate), and polydimethylsiloxane as a polysiloxane (KF-96-60000 manufactured by Shin-Etsu Chemical Co., Ltd.; in the general formula (2), R 1 、R 2 、R 5 ~R 10Each of them was a methyl group, m = 0, average fluorination rate of polysiloxane structure = 0, weight average molecular weight 95,000) 10 parts by mass, and 0.036 parts by mass of dodecyl mercaptan as a polymerization regulator were introduced. After making a homogeneous solution under stirring, vacuum degassing and nitrogen purging of the reaction system were carried out 5 times using a diaphragm pump. Under a nitrogen flow, 0.036 parts by mass of perocta O (1,1,3,3 - tetramethylbutyl peroxy - 2 - ethylhexanoate; peroxide - based radical polymerization initiator; manufactured by NOF Corporation) as a radical polymerization initiator was introduced from the sample inlet. Then, under a nitrogen atmosphere, the polymerization reaction was carried out by stirring at a polymerization temperature of 70 °C for 8 hours to obtain a solution of the defoaming agent. The average particle diameter of the defoaming agent particles in the dispersion measured by the above procedure was 0.20 μm.

[0136] (Production Example 2, 3) (A) Monomer, (B) polysiloxane, (C) polymerization solvent, radical initiator, and polymerization regulator, and defoaming agents B and C were produced by solution polymerization in the same manner as in Production Example 1 except that the amounts used thereof were changed as shown in Table 1.

[0137] (Production Example 4) The defoaming agent D was produced by solution polymerization according to the following procedure. Into a 100 mL four - necked flask equipped with a polytetrafluoroethylene stirring blade (with vacuum seal), Dimroth condenser, three - way cock for nitrogen introduction, and sample inlet, 30 parts by mass of diisobutyl ketone as a polymerization solvent, 1.8 parts by mass of stearyl methacrylate and 0.2 parts by mass of EGDMA as monomers, and fluorosilicone as polysiloxane (a concentrate obtained by distilling off the diluent under reduced pressure from FA - 600 manufactured by Shin - Etsu Chemical Co., Ltd.; in the general formula (2), R 1 、R 2 、R 4 、R 5 ~R 10 were each a methyl group, R 3(A 3,3,3-trifluoropropyl group, average fluorination rate of the polysiloxane structure = 0.5, weight average molecular weight 30,000) 10 parts by mass, and 0.036 parts by mass of dodecyl mercaptan as a polymerization regulator were introduced, and after being made into a uniform solution under stirring, vacuum degassing and nitrogen purging of the reaction system were carried out 5 times using a diaphragm pump. Under a nitrogen flow, 0.036 parts by mass of perocta O (1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate; peroxide-based radical polymerization initiator; manufactured by NOF Corporation) as a radical polymerization initiator was introduced from the sample inlet, and then, under a nitrogen atmosphere, the polymerization reaction was carried out by stirring at a polymerization temperature of 70 °C for 8 hours to obtain a solution of an antifoaming agent. The average particle diameter of the antifoaming agent particles in the dispersion measured by the above procedure was 0.20 μm.

[0138] (Production Examples 5 to 14) (A) Monomer, (B) polysiloxane, (C) polymerization solvent, radical initiator, and polymerization regulator, and antifoaming agents E to N were produced by solution polymerization in the same manner as in Production Example 4 except that the amounts used thereof were changed as shown in Tables 1 to 2.

[0139] (Production Example 15) Polymethacrylate was produced by solution polymerization in the same manner as in Production Example 4 except that (B) polysiloxane was not blended in the polymerization system. Then, fluorosilicone (a concentrate obtained by distilling off the diluent from FA-600 manufactured by Shin-Etsu Chemical Co., Ltd. under reduced pressure; in the general formula (2), R 1 , R 2 , R 4 , R 5 ~R 10 are each a methyl group, and R 3 is a 3,3,3-trifluoropropyl group, average fluorination rate of the polysiloxane structure = 0.5, weight average molecular weight 30,000) 10 parts by mass was added and mixed to prepare antifoaming agent R.

[0140]

Table 1

[0141]

Table 2

[0142] <Examples 1 to 21 and Comparative Examples 1 to 3> As shown in Tables 3 to 4, lubricating oil compositions of the present invention (Examples 1 to 21) and lubricating oil compositions for comparison (Comparative Examples 1 to 3) were prepared, respectively. In Tables 3 to 4, "mass%" in the item of "base oil composition" means mass% based on the total amount of the base oil, and "mass%" in other items means mass% based on the total amount of the lubricating oil composition. "Si ppm" means mass ppm in terms of the amount of silicon based on the total amount of the composition. When blending an antifoaming agent into the lubricating oil composition, an antifoaming agent or a solution or dispersion containing the antifoaming agent was added to kerosene and stirred well to prepare a diluted solution in which the antifoaming agent was dissolved in kerosene (antifoaming agent concentration: 0.3 mass% as the amount of silicon based on the total amount of the diluted solution). Then, while dropping the diluted solution into the lubricating oil composition and stirring and mixing, a lubricating oil composition having the antifoaming agent concentration described in Tables 3 to 4 was prepared. In Tables 3 to 4, the details of components other than antifoaming agents A to N and R manufactured in Production Examples 1 to 15 are as follows.

[0143] (Base oil) O-1: Hydrorefined mineral oil, kinematic viscosity (100 °C): 2.2 mm 2 / s, kinematic viscosity (40 °C): 7.5 mm 2 / s, viscosity index 106 O-2: Hydrorefined mineral oil, kinematic viscosity (100 °C): 4.2 mm 2 / s, kinematic viscosity (40 °C): 19.6 mm 2 / s, viscosity index 123 O-3: Ester-based base oil, kinematic viscosity (100 °C): 2.7 mm 2 / s, kinematic viscosity (40 °C): 8.6 mm 2 / s, viscosity index 178

[0144] (Antifoaming agent) Antifoaming agent P: Dimethyl silicone antifoaming agent (KF-96-50000CS manufactured by Shin-Etsu Chemical Co., Ltd., weight average molecular weight 95,000) Defoaming agent Q: Fluorosilicone defoaming agent (FA-600 manufactured by Shin-Etsu Chemical Co., Ltd., weight average molecular weight 30,000)

[0145] (Other additives) V-1: Polymethacrylate viscosity index improver, weight average molecular weight: 20,000 W-1: Additive package (including boron-modified succinimide, phosphorus-based antiwear agent, Ca sulfonate detergent, ashless friction modifier, antioxidant, and metal deactivator)

[0146]

Table 3

[0147]

Table 4

[0148] (Evaluation of defoaming property of new oil (1): Homogenizer test) For each of the lubricating oil compositions of Examples 1 to 21 and Comparative Examples 1 to 3, the defoaming property was evaluated using the homogenizer tester shown in Figure 1. The homogenizer tester shown in Figure 1 includes a homogenizer 1, a cylindrical heater 2 for heating, a temperature controller 3, a thermocouple 4 for measuring the oil temperature, a power supply 5 for heating the heater, a glass cylinder 6 corresponding to an oil tank (a cylindrical glass container with graduations, inner diameter 40 mm, depth 300 mm, graduations: 0 to 250 mL at 2 mL intervals), and an air blowing tube (air inflow rate 30 mL / min) 7. 150 mL of the sample oil was placed in the glass cylinder 6, and the temperature of the sample oil was set to 120 °C using the cylindrical heater 2 for heating. The oil level at this time was defined as the reference oil level 8. Stirring was started using the homogenizer 1, and the difference between the oil level after 10 minutes and the reference oil level was defined as the foaming amount. The results are shown in Tables 3 to 4.

[0149] (Evaluation of storage stability and centrifugal durability (1): Homogenizer test) (a) Centrifugal separation Four centrifuge tubes containing sample oil were prepared, with the sample oil filled up to the 60 mL graduation line of the glass centrifuge tubes. These four centrifuge tubes containing sample oil were set in a centrifuge and rotated at 25 °C and a rotation speed of 10,000 rpm for 180 minutes. The relative centrifugal force during this rotation was an average of 8,000 G. After centrifugation, a total of 200 mL of the supernatant was collected. (b) Homogenizer test For the collected supernatant, the defoaming property was evaluated by the same homogenizer test as described above. The results are shown in Tables 3 to 4. The less the increase in the amount of foaming after centrifugation, the less likely the separation and sedimentation of the defoaming agent during storage, and the less the decrease in the defoaming performance due to the centrifugal action.

[0150] (Evaluation of storage stability and centrifugal durability (2): Measurement of silicon content in oil) (a) Measurement of silicon content in fresh oil For each of the above-prepared lubricating oil compositions, the silicon content in the fresh oil was measured by inductively coupled plasma (ICP) emission spectrometry. (b) Measurement of silicon content in oil after centrifugation For each of the above-prepared lubricating oil compositions, centrifugation was performed in the same manner as above (at 25 °C, 8,000 G for 180 minutes). For the collected supernatant, the silicon content in the oil was measured by ICP emission spectrometry in the same manner as above. The closer the silicon content in the oil after centrifugation is to the silicon content in the fresh oil, the less likely the separation and sedimentation of the defoaming agent during storage, and the less the loss of the defoaming agent due to the centrifugal action.

[0151] As can be seen from Tables 3 to 4, all of the lubricating oil compositions (Examples 1 to 21) containing the defoaming agent of the present invention had good defoaming properties not only for the fresh oil but also for the sample oil after centrifugation. Also, in these lubricating oil compositions of the present invention, the decrease in the silicon content in the oil was kept low even after centrifugation. In contrast, for the lubricating oil compositions of Comparative Examples 1 to 3 using defoaming agents outside the scope of the present invention, the defoaming property of the sample oil after centrifugation deteriorated significantly compared to the defoaming property of the fresh oil. Also, for the lubricating oil compositions of these comparative examples, the silicon content in the oil decreased significantly after centrifugation.

[0152] From the above test results, according to the defoaming agent and lubricating oil composition of the present invention, it is shown that the decrease in defoaming performance can be suppressed even during long-term storage, and the defoaming performance of the lubricating oil can be maintained over a long period even in a lubricating environment where a high centrifugal action acts on the lubricating oil.

Industrial Applicability

[0153] The defoaming agent and lubricating oil composition of the present invention can suppress the decrease in defoaming performance even during long-term storage, and can maintain the defoaming performance of the lubricating oil over a long period even under lubricating conditions where a centrifugal action acts on the lubricating oil. Therefore, the defoaming agent and lubricating oil composition of the present invention can be preferably adopted for any lubricating oil composition that requires defoaming performance. Among them, it can be particularly preferably adopted in lubricating oils used under lubricating conditions where a centrifugal action acts on the lubricating oil, such as automotive engine oils, automotive (which may be an electric vehicle) transmission oils, or automotive transaxle oils.

Explanation of Symbols

[0154] 1 Homogenizer 2 Cylindrical heater for heating 3 Thermostat 4 Thermocouple for measuring oil temperature 5 Power supply for heater heating 6 Glass cylinder corresponding to an oil tank (cylindrical glass container with graduations, inner diameter 40 mm, depth 300 mm, graduations: 0 - 250 mL at 2 mL intervals) 7 Air blowing tube (air inflow rate 30 mL / min) 8 Reference oil level

Claims

1. A method for producing an antifoaming agent, which comprises polymerizing (A) at least one polymerizable monomer selected from the group consisting of (meth)acrylate esters represented by any one of general formulas (7) to (9) in (C) a solvent in which (B) one or more non-polymerizable polysiloxanes are dissolved, wherein component (A) contains less than 10% by mass or does not contain one or more monomers containing an Si atom, based on the total amount of component (A); A method for producing an antifoaming agent. 【Chemical 1】 (In general formula (7), R １３ represents a hydrogen atom or a methyl group, and R １４ represents a linear or branched hydrocarbon group having 1 to 5 carbon atoms.) 【Chemical 2】 (In general formula (8), R １５ represents a hydrogen atom or a methyl group, and R １６ represents a linear or branched hydrocarbon group having 6 to 18 carbon atoms.) 【Chemical 3】 (In general formula (9), R １７ represents a hydrogen atom or a methyl group, and R １８ represents a linear or branched hydrocarbon group having １９ or more carbon atoms.)

2. The method for producing an antifoaming agent according to claim 1, wherein component (B) contains one or more polysiloxanes represented by the following general formula (2). 【Chemical Formula 4】 (In general formula (2), the order of the polysiloxane repeating units is arbitrary; R １ and R ２ are each independently a non-polymerizable organic group having 1 to 18 carbon atoms and not containing a fluorine atom; R ３ and R ４ each independently represents a non-polymerizable organic group containing a fluorine atom or a non-polymerizable organic group having 1 to 18 carbon atoms and not containing a fluorine atom, and at least one of R ３ and R ４ is a non-polymerizable organic group containing three or more fluorine atoms; R ５ 、 R ６ 、 R ７ 、 R ８ 、 R ９ 、 and R １０ are each independently a non-polymerizable organic group having 1 to 18 carbon atoms; n and m are each independently an integer of 0 or more; n + m is 1 or more; The ratio m / (n + m) is 0 to 1.)

3. In the general formula (2), R １ and R ２ each independently represents a saturated hydrocarbon group having 1 to 6 carbon atoms and not containing a fluorine atom, or an aromatic hydrocarbon group having 6 to 10 carbon atoms and optionally having one or more alkyl substituents and not containing a fluorine atom; R ３ and R ４ each independently represents a non-polymerizable organic group containing a fluorine atom, a saturated hydrocarbon group having 1 to 6 carbon atoms and not containing a fluorine atom, or an aromatic hydrocarbon group having 6 to 10 carbon atoms which may have one or more alkyl substituents and does not contain a fluorine atom, and R ３ and R ４ at least one of them is a non-polymerizable organic group containing 3 or more fluorine atoms; R ５ 、R ６ 、R ７ 、R ８ 、R ９ 、and R １０ are each independently a saturated hydrocarbon group having 1 to 6 carbon atoms, or an aromatic hydrocarbon group having 6 to 10 carbon atoms which may have one or more alkyl substituents and does not contain a fluorine atom. The method for producing an antifoaming agent according to claim 2.

4. In the general formula (2), R １ and R ２ are each independently an alkyl group having 1 to 3 carbon atoms and not containing a fluorine atom, or a phenyl group; R ３ and R ４ are each independently a non-polymerizable organic group containing a fluorine atom, an alkyl group having 1 to 3 carbon atoms not containing a fluorine atom, or a phenyl group, and at least one of R ３ and R ４ is a non-polymerizable organic group containing 3 or more fluorine atoms; R ５ 、R ６ 、R ７ 、R ８ 、R ９ 、and R １０ are each independently an alkyl group having 1 to 3 carbon atoms or a phenyl group. The method for producing an antifoaming agent according to claim 2 or 3.

5. The method for producing an antifoaming agent according to any one of claims 1 to 4, wherein the weight average molecular weight of component (B) is 5,000 to 500,000.

6. A method for producing a lubricating oil composition, which comprises including an antifoaming agent produced by the method for producing an antifoaming agent according to any one of claims 1 to 5 in a lubricating base oil.

7. An antifoaming agent containing a polysiloxane, which contains at least any one of stearyl methacrylate, dodecyl methacrylate, and 2-ethylhexyl methacrylate as components, and has an average particle diameter of the antifoaming agent in a dispersion liquid in which the antifoaming agent is finely dispersed by adding 10 mL of mineral oil to 1 mL of a solution containing the antifoaming agent and stirring at a rotation speed of 200 rpm for 30 minutes at room temperature using a cylindrical magnetic stirrer having a diameter of 8 mm and a length of 30 mm in a 100 mL beaker, and the average particle diameter is 0.05 μm or more and 10 μm or less. An antifoaming agent.

8. The antifoaming agent according to claim 7, wherein the silicon content is 1 ppm by mass or more and 100 ppm by mass or less based on the total amount of the antifoaming agent.

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