Methods for producing compositions, friction reducers, lubricant compositions, and (meth)acrylic polymers

Abstract

The present invention provides a composition, a friction reducing agent, a lubricant composition, and a method for producing a (meth)acrylic polymer that exhibits excellent friction reduction and wear resistance. [Solution] In one example, the composition contains a (meth)acrylic polymer (A) having a terminal structure in which at least two adjacent carbon atoms are bonded to hydroxyl groups, and a base oil. In another example, the composition contains a (meth)acrylic polymer (A) having a terminal structure derived from a chain transfer agent having two or more hydroxyl groups, and a base oil.

Description

[Technical Field]

[0001] The present invention relates to a composition, a friction reducer, a lubricant composition, and a method for producing (meth)acrylic polymers. [Background technology]

[0002] Lubricant compositions, such as those found in automobile engine oil and drivetrain fluids, often contain a base oil and multiple additives. One type of additive, friction reducers, can provide benefits such as reduced energy loss through friction reduction and extended equipment lifespan by preventing seizing. In recent years, with the trend towards lower viscosity lubricants for fuel efficiency, the load on metal-to-metal contact surfaces has become increasingly severe, making the role of friction reducers even more crucial.

[0003] Examples of friction reducing agents include oiliness enhancers such as long-chain fatty acid esters and fatty acid amides, anti-wear agents such as phosphate esters and zinc dithiophosphate, extreme pressure agents such as organic sulfur compounds and organic halogen compounds, and friction modifiers such as organic molybdenum compounds. However, depending on the usage conditions and environment, these additives may not provide sufficient friction reduction. To overcome this problem, the use of polymer materials as friction reducing agents is being considered (for example, Patent Document 1). Patent Document 1 discloses copolymers having constituent units derived from alkyl acrylates and constituent units derived from hydroxyalkyl acrylates as friction and wear reducing agents for lubricating oils. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-124266 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, the friction-reducing agent for lubricating oil described in Patent Document 1 is insufficient in terms of friction reduction. Furthermore, there is room for improvement in wear resistance.

[0006] The main object of the present invention is to provide a composition, a friction reducing agent, a lubricant composition, and a method for producing a (meth)acrylic polymer that exhibits excellent friction reduction and wear resistance. [Means for solving the problem]

[0007] The present invention has the following aspects. [1] A composition comprising a (meth)acrylic polymer (A) having a terminal structure in which at least two adjacent carbon atoms are each bonded to a hydroxyl group, and a base oil. [2] A composition comprising a (meth)acrylic polymer (A) having terminal structures derived from a chain transfer agent having two or more hydroxyl groups, and a base oil. [3] The composition according to [1] or [2], wherein the (meth)acrylic polymer (A) has a terminal structure derived from thioglycerol. [4] The composition according to any one of [1] to [3], wherein the (meth)acrylic polymer (A) has constituent units derived from (meth)acrylate having an alkyl group having 1 to 30 carbon atoms. [5] The composition according to any one of [1] to [4], wherein the mass-average molecular weight of the (meth)acrylic polymer (A) is 1,000 to 50,000. [6] The composition according to any one of [1] to [5], wherein the hydroxyl group content of the (meth)acrylic polymer (A) is 0.01 to 1.0 mmol / g. A friction reducing agent containing any of the compositions described in [7][1] to [6]. A lubricating composition containing any of the compositions described in [8][1] to [6].

[0008] [9] A method for producing a (meth)acrylic polymer, comprising polymerizing a mixture containing a chain transfer agent having two or more hydroxyl groups and a (meth)acrylate having an alkyl group having 8 to 30 carbon atoms in a base oil.

[10] The production method according to [9], wherein the mixture contains thioglycerol.

[11] The production method according to [9] or

[10] , wherein the mixture contains a monomer having a SP value of the homopolymer of 20.0 (J / cm 3 ) 1 / 2 or more. [Advantages of the Invention]

[0009] According to the present invention, it is possible to provide a composition, a friction reducing agent, a lubricant composition, and a method for producing a (meth)acrylic polymer, which are excellent in friction reducing effect and also excellent in wear resistance. [Modes for Carrying Out the Invention]

[0010] The meanings of the terms are as follows. "(Meth)acrylic" is a general term for "acrylic" and "methacrylic". "(Meth)acrylate" is a general term for "acrylate" and "methacrylate". "(Meth)acryloyl group" is a general term for "acryloyl group" and "methacryloyl group", and is a group represented by CH2 = C(R)-C(=O)- (R is a hydrogen atom or a methyl group). "Macromonomer" means a polymer having a radically polymerizable group or an addition-reactive functional group. "Radically polymerizable monomer" means a monomer having an ethylenically unsaturated bond that is not a macromonomer. "~" indicating a numerical range means that the numerical values described before and after it are included as the lower limit value and the upper limit value. The numerical ranges disclosed in this specification can be combined arbitrarily with the lower limit value and the upper limit value to form a new numerical range.

[0011] Hereinafter, some embodiments will be described. However, the following description relates to representative examples, and the present invention is not limited to the following description.

[0012] [Composition] A composition according to one aspect of the present invention contains a (meth)acrylic polymer (A) having a terminal structure in which hydroxyl groups are bonded to at least two adjacent carbon atoms, and a base oil. In this aspect, the (meth)acrylic polymer (A) has a terminal structure in which hydroxyl groups are bonded to at least two adjacent carbon atoms, respectively. Therefore, the friction reduction effect is improved.

[0013] Another embodiment of the present invention provides a composition containing a (meth)acrylic polymer (A) having terminal structures derived from a chain transfer agent having two or more hydroxyl groups, and a base oil. In this embodiment, the (meth)acrylic polymer (A) has terminal structures derived from a chain transfer agent having two or more hydroxyl groups. Therefore, the friction reduction effect is improved.

[0014] The composition of the present invention may further contain other components besides the (meth)acrylic polymer (A) and the base oil. The embodiments of each component will be described in detail below, but the present invention is not limited to the following description.

[0015] ((meth)acrylic polymer (A)) The hydroxyl group content of (meth)acrylic polymer (A) is preferably 0.01 to 1.0 mmol / g, more preferably 0.01 to 0.70 mmol / g, even more preferably 0.05 to 0.50 mmol / g, and particularly preferably 0.10 to 0.40 mmol / g, as expressed per gram of (meth)acrylic polymer (A). When the hydroxyl group content of (meth)acrylic polymer (A) is above the lower limit, the adsorption to the material increases, and the friction reduction effect is further improved. When the hydroxyl group content of (meth)acrylic polymer (A) is below the upper limit, the solubility in the base oil improves. In addition, the friction reduction effect is improved. The hydroxyl group content represents the content of the hydroxyl group-containing compound in the total amount of monomer, chain transfer agent, and initiator in the (meth)acrylic polymer (A).

[0016] To introduce terminal structures in which hydroxyl groups are bonded to at least two adjacent carbon atoms into a (meth)acrylic polymer (A), the monomer components can be polymerized in the presence of a chain transfer agent having two or more hydroxyl groups. This method yields a (meth)acrylic polymer (A) having structural units derived from a chain transfer agent having two or more hydroxyl groups at the ends of the main chain polymer structure or the side chain polymer structure. The chain transfer agent having two or more hydroxyl groups is preferably a mercaptan-based chain transfer agent having two or more hydroxyl groups and one mercapto group.

[0017] The chain transfer agents having two or more hydroxyl groups are not particularly limited, but examples include thioglycerol, 1-mercapto-1,1-methanediol, 1-mercapto-1,1-ethanediol, 3-mercapto-1,2-propanediol, 2-mercapto-1,2-propanediol, 2-mercapto-2-methyl-1,3-propanediol, 2-mercapto-2-ethyl-1,3-propanediol, 1-mercapto-2,2-propanediol, 2-mercaptoethyl-2-methyl-1,3-propanediol, and 2-mercaptoethyl-2-ethyl-1,3-propanediol.

[0018] For example, the (meth)acrylic polymer (A) preferably has a thioglycerol-derived terminal structure as shown below, in which a hydroxyl group is bonded to at least two adjacent carbon atoms.

[0019] [ka]

[0020] The thioglycerol-derived terminal structure may be located at the end of the main chain polymer structure of the (meth)acrylic polymer (A), or at the end of the side chain polymer structure. It is preferable that the (meth)acrylic polymer (A) has the thioglycerol-derived terminal structure at the end of the main chain polymer structure, as this can further enhance the friction reduction effect.

[0021] Constituent units derived from (meth)acrylates having alkyl groups with 1 to 30 carbon atoms: The (meth)acrylic polymer (A) may have constituent units derived from (meth)acrylate having an alkyl group with 1 to 30 carbon atoms. Hereinafter, (meth)acrylate having an alkyl group with 1 to 30 carbon atoms will be referred to as "monomer (a)".

[0022] Examples of monomers (a) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, n-dodecyl ( Alkyl(meth)acrylates having linear alkyl groups such as meth)acrylate, n-tridecyl(meth)acrylate, n-tetradecyl(meth)acrylate, n-pentadecyl(meth)acrylate, n-cetyl(meth)acrylate, n-heptadecyl(meth)acrylate, n-stearyl(meth)acrylate, n-behenyl(meth)acrylate; i-propyl(meth)acrylate, i-butyl(meth)acrylate, t-butyl (meth)acrylate, i-nonyl(meth)acrylate, i-decyl(meth)acrylate, i-undecyl(meth)acrylate, i-dodecyl(meth)acrylate, i-tridecyl(meth)acrylate, i-tetradecyl(meth)acrylate, i-pentadecyl(meth)acrylate, i-cetyl(meth)acrylate, i-heptadecyl(meth)acrylate, i-stearyl(meth)acrylate, i-octadecyl(meth)acrylate Examples include alkyl(meth)acrylates having branched alkyl groups such as i-behenyl(meth)acrylate and 2-ethylhexyl(meth)acrylate; and alkyl(meth)acrylates having cyclic alkyl groups such as cyclopentyl(meth)acrylate, cyclohexyl(meth)acrylate, dicyclopentanyl(meth)acrylate, isobornyl(meth)acrylate, and 4-t-butylcyclohexyl(meth)acrylate. Monomer (a) may be used alone or in combination of two or more types.

[0023] As monomer (a), a (meth)acrylate having a linear or branched alkyl group is preferred in terms of its high solubility in the base oil, a (meth)acrylate having a linear or branched alkyl group having 4 to 20 carbon atoms is more preferred, a (meth)acrylate having a linear or branched alkyl group having 8 to 18 carbon atoms is even more preferred, and a (meth)acrylate having a linear or branched alkyl group having 10 to 14 carbon atoms is particularly preferred.

[0024] Other radical polymerizable monomer-derived constituent units: The (meth)acrylic polymer (A) may contain structural units derived from other radical polymerizable monomers other than monomer (a). Hereinafter, other radical polymerizable monomers will be referred to as "monomer (b)".

[0025] Examples of monomer (b) include styrene, α-methylstyrene, pt-butylstyrene, vinyltoluene, vinyl acetate, and (meth)acrylate compounds other than monomer (a).

[0026] Examples of (meth)acrylate compounds other than monomer (a) include hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate; (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-maleic acid -(meth)acrylates containing carboxyl groups such as 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate; phenyl(meth)acrylate, benzyl(meth)acrylate, phenoxyethyl(meth)acrylate, phenoxydiethylene glycol(meth)acrylate, phenoxypolyethylene glycol(meth)acrylate, nonylphenoxypolyethylene glycol(meth)acrylate, phenoxypolypropylene glycol( (meth)acrylates having an aromatic ring structure such as meth)acrylate, phenylphenyl(meth)acrylate, phenylphenoxyethyl(meth)acrylate, phenoxybenzyl(meth)acrylate, phenylbenzyl(meth)acrylate, naphthyl(meth)acrylate, (1-naphthyl)methyl(meth)acrylate; (meth)acrylates having a heterocyclic structure such as tetrahydrofurfuryl(meth)acrylate, glycidyl(meth)acrylate, (meth)acrylateoilmorpholin; methoxyethyl(meth)acrylate Examples include alkoxyalkyl (meth)acrylates such as ethoxyethyl (meth)acrylate and butoxyethyl (meth)acrylate; 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and (meth)acrylamide. Monomer (b) may be used alone or in combination of two or more types.

[0027] Polymer composition: The proportion of constituent units derived from monomer (a) in the (meth)acrylic polymer (A) is preferably 50.0 to 99.99% by mass, more preferably 60 to 99.95% by mass, and even more preferably 70 to 99.9% by mass, relative to the total mass of the (meth)acrylic polymer (A), in order to improve solubility in the base oil.

[0028] The proportion of constituent units derived from monomer (b) in the (meth)acrylic polymer (A) is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and even more preferably 0 to 10% by mass, based on the total mass of the (meth)acrylic polymer (A). The (meth)acrylic polymer (A) does not need to contain constituent units derived from monomer (b).

[0029] The total proportion of constituent units derived from monomer (a) and monomer (b) in (meth)acrylic polymer (A) shall not exceed 100% by mass of the total mass of (meth)acrylic polymer (A).

[0030] Properties of (meth)acrylic polymer (A): The (meth)acrylic polymer (A) may be a block copolymer or a graft copolymer, as this improves its solubility in the base oil. A graft copolymer is preferred because it can further improve the friction reduction effect.

[0031] A "graft copolymer" is a polymer having one or more blocks chemically bonded to a main chain polymer structure (stem polymer structure) as side chain polymer structures (branch polymer structures). The structures of the main chain polymer and the side chain polymers may be different or the same.

[0032] The method for producing the graft copolymer is not particularly limited, but examples include the following methods (1), (2), and (3).

[0033] Method (1): A method of radically polymerizing macromonomers having a radically polymerizable double bond at the terminal as a side-chain polymer structure, and then radically polymerizing the monomers that will become the constituent units of the main-chain polymer with the macromonomers. Method (2): A method of first preparing a main chain polymer having reaction sites and a macromonomer having reaction sites, and then reacting them. Method (3): A method for producing a side-chain polymer structure by generating radicals on the main-chain polymer using an initiator with hydrogen abstraction ability after the main-chain polymer has been produced, and then reacting with monomers that will become the constituent units of the side-chain polymer.

[0034] In the case of graft copolymers, the constituent units derived from monomer (a) and monomer (b) may be present in either the main chain polymer structure or the side chain polymer structure of the (meth)acrylic polymer (A).

[0035] When the (meth)acrylic polymer (A) has constituent units derived from monomer (a) in its main chain polymer structure or side chain polymer structure, its solubility in base oil can be improved. In particular, it is preferable that the (meth)acrylic polymer (A) has constituent units derived from monomer (a) in its side chain polymer structure, as this improves its solubility in base oil.

[0036] When the (meth)acrylic polymer (A) is a graft copolymer, the (meth)acrylic polymer (A) may have constituent units derived from a radical polymerizable monomer (m1) (hereinafter also referred to as "component (m1)") and constituent units derived from a macromonomer (M) (hereinafter also referred to as "component (M)"). By copolymerizing component (m1) and component (M), a graft copolymer can be obtained having a main chain polymer structure with component (m1) as a constituent unit and a side chain polymer structure derived from component (M).

[0037] The (m1) component may be the same compound as monomer (a) and monomer (b). It is preferable that the (m1) component contains a (meth)acrylate compound due to its excellent radical polymerization properties.

[0038] Component (M) is not particularly limited as long as it is a compound having a radical polymerizable group and a repeating structure. Examples of components (M) include the following compounds:

[0039] Compounds obtained by modifying the ends of polyisobutylene or hydrogenated polybutadiene with vinyl-based radical polymerizable groups. A compound having two or more constituent units derived from a radical polymerizable monomer (m2) (hereinafter also referred to as "(m2) component") and having a radical polymerizable group at its terminus.

[0040] Due to its high degree of design for solubility in base oils, component (M) is preferably a compound having two or more constituent units derived from component (m2) and having a radical polymerizable group at its terminus.

[0041] The (m2) component can be the same compound as monomer (a) and monomer (b). A (meth)acrylate compound is preferred as the (m2) component due to its excellent radical polymerization properties. Monomer (a) is preferred as the (m2) component because it can improve solubility in the base oil.

[0042] Component (M) preferably has the structure shown in the following formula (1) from the viewpoint of radical polymerization.

[0043] [ka]

[0044] In formula (1), X 1 ~X p-1 Each of these independently represents a hydrogen atom, a methyl group, or CH2OH, and Y 1 ~Y p Each of these independently comprises X, a radical polymerizable monomer (m2) which is a constituent unit of the macromonomer (M). 1 ~X p-1 This shows substituents on unsaturated hydrocarbons other than those specified. Z represents a terminal group, and p represents an integer from 2 to 10000.

[0045] X 1 ~X n-1 and Y 1 ~Y p is, independently, a substituent of an unsaturated hydrocarbon of the (m2) component. Y 1 ~Y p is, for example, OR 11 , a halogen atom, COR 12 , COOR 13 , CN, CONR 14 R 15 , NHCOR 16 , or R 17 represents, and R 11 ~R 17 each independently represents a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, etc. The terminal group Z includes a hydrogen atom and a group derived from a radical polymerization initiator, similar to the terminal groups of polymers obtained by known radical polymerization.

[0046] From the viewpoint of improving the solubility of the (meth)acrylic polymer (A) in the base oil, the proportion of the structural unit derived from the (M) component in the (meth)acrylic polymer (A) is preferably 1 to 50% by mass, more preferably 2 to 40% by mass, and still more preferably 3 to 30% by mass, based on the total mass of the (meth)acrylic polymer (A).

[0047] From the viewpoint of improving the solubility of the (meth)acrylic polymer (A) in the base oil, the proportion of the structural unit derived from the monomer (a) in the total mass of the (M) component is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0048] From the viewpoint of improving the solubility of the (meth)acrylic polymer (A) in the base oil, the mass average molecular weight (Mw) measured by gel permeation chromatography (GPC) of the (M) component is preferably 1000 to 50000, more preferably 2000 to 40000, and still more preferably 3000 to 30000.

[0049] To ensure good solubility of the (meth)acrylic polymer (A) in the base oil, the number-average molecular weight (Mn) of component (M), as measured by gel permeation chromatography, is preferably 500 to 30,000, more preferably 1,000 to 25,000, and particularly preferably 2,000 to 20,000.

[0050] To ensure good solubility of the (meth)acrylic polymer (A) in the base oil, the molecular weight distribution (Mw / Mn) of component (M), as measured by gel permeation chromatography (GPC), is preferably 1.0 to 10, more preferably 1.2 to 8.0, and even more preferably 1.5 to 5.0.

[0051] Component (M) may be manufactured by known methods or may be a commercially available product. Examples of methods for manufacturing component (M) include a method using a cobalt chain transfer agent (U.S. Patent No. 4,680,352), a method using an α-substituted unsaturated compound such as α-bromomethylstyrene as a chain transfer agent (International Publication No. 88 / 04304), a method of chemically bonding polymerizable groups (Japanese Patent Publication No. 60-133007 and U.S. Patent No. 5,147,952), and a method by thermal decomposition (Japanese Patent Publication No. 11-240,854).

[0052] The method using a cobalt chain transfer agent is preferred because it involves fewer manufacturing steps and utilizes a catalyst with a high chain transfer constant. Since cobalt chain transfer agents have a high chain transfer constant, a small amount of addition can be used to obtain macromonomers with controlled molecular weights.

[0053] Known cobalt complexes can be used as cobalt chain transfer agents. The amount of the cobalt chain transfer agent is preferably 0.00001 to 0.1 parts by mass, more preferably 0.00005 to 0.05 parts by mass, and particularly preferably 0.0001 to 0.02 parts by mass, per 100 parts by mass of component (m2).

[0054] From the standpoint of increasing the solubility of the (meth)acrylic polymer (A) in the base oil and enhancing the friction reduction effect, the lower limit of the mass-average molecular weight (Mw) of the (meth)acrylic polymer (A) measured by gel permeation chromatography (GPC) is preferably 1000 or more, more preferably 3000 or more, and even more preferably 5000 or more. From the standpoint of increasing the solubility of the (meth)acrylic polymer (A) in the base oil and lowering the viscosity of the composition, the upper limit of the mass-average molecular weight (Mw) of the (meth)acrylic polymer (A) measured by gel permeation chromatography (GPC) is preferably 500,000 or less, more preferably 300,000 or less, even more preferably 100,000 or less, and particularly preferably 50,000 or less.

[0055] In order to improve the solubility of the (meth)acrylic polymer (A) in the base oil and to improve the friction reduction effect, the lower limit of the number average molecular weight (Mn) of the (meth)acrylic polymer (A) measured by gel permeation chromatography (GPC) is preferably 300 or more, more preferably 1000 or more, even more preferably 3000 or more, and particularly preferably 5000 or more. The upper limit is preferably 300,000 or less, more preferably 100,000 or less, even more preferably 50,000 or less, and particularly preferably 30,000 or less.

[0056] In order to improve the solubility of the (meth)acrylic polymer (A) in the base oil and to improve the friction reduction effect, the molecular weight distribution (Mw / Mn) of the (meth)acrylic polymer (A), as measured by gel permeation chromatography (GPC), is preferably 1.0 to 30, more preferably 1.2 to 20, and even more preferably 1.5 to 10.

[0057] Method for producing (meth)acrylic polymers: The (meth)acrylic polymer (A) and the compositions of the present invention can be produced by polymerizing a mixture containing a chain transfer agent having two or more hydroxyl groups and a (meth)acrylate having an alkyl group having 1 to 30 carbon atoms in a base oil. A more preferred method of production is to polymerize a mixture containing a chain transfer agent having two or more hydroxyl groups and a (meth)acrylate having an alkyl group having 8 to 30 carbon atoms in a base oil. The compositions of the present invention may also be obtained by compounding the (meth)acrylic polymer (A) with a base oil.

[0058] The chain transfer agents having two or more hydroxyl groups are not particularly limited, but examples include thioglycerol, 1-mercapto-1,1-methanediol, 1-mercapto-1,1-ethanediol, 3-mercapto-1,2-propanediol, 2-mercapto-1,2-propanediol, 2-mercapto-2-methyl-1,3-propanediol, 2-mercapto-2-ethyl-1,3-propanediol, 1-mercapto-2,2-propanediol, 2-mercaptoethyl-2-methyl-1,3-propanediol, and 2-mercaptoethyl-2-ethyl-1,3-propanediol. A chain transfer agent having two or more hydroxyl groups may be used alone or in combination of two or more.

[0059] The mixture for polymerization has a homopolymer SP value (δ) of 20.0 (J / cm²). 3 ) 1 / 2 It is preferable to contain monomers that meet the above criteria. The SP value (δ) of the homopolymer is an abbreviation for Solubility Parameter and can be determined by Fedors' method described in Polymer Engineering and Science, Vol. 14, 147 (1974).

[0060] The SP value of the homopolymer is 20.0 (J / cm²). 3 ) 1 / 2The monomers described above are not particularly limited, but examples include methyl (meth)acrylate, (meth)acrylic acid, ethyl acrylate, acrylamide, dimethylacrylamide, diethylacrylamide, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, styrene, vinyl acetate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, and methoxyethyl (meth)acrylate.

[0061] Alternatively, it can be produced by polymerizing a chain transfer agent having two or more hydroxyl groups and a mixture containing components (m1) and (M) in a base oil. As component (M), macromonomers obtained by polymerizing a monomer mixture containing radically polymerizable monomers in a base oil using a cobalt chain transfer agent are preferred. Because cobalt chain transfer agents have a high chain transfer constant, macromonomers with controlled molecular weights can be obtained by adding only a small amount.

[0062] (Base oil) The base oil is not particularly limited. The base oil may be a mineral base oil refined from crude oil, or a chemically synthesized synthetic oil. Examples of base oils include API Group III base oils such as YUBASE3 from SK Lubricants, API Group III Plus base oils such as YUBASE4 from SK Lubricants, and API Group IV base oils such as polyalphaolefins.

[0063] (Other ingredients) Other components include, for example, antioxidants, viscosity index improvers, pour point depressants, cleaning dispersants, corrosion inhibitors, rust inhibitors, defoamers, emulsifiers, fungicides, and anti-emulsifiers.

[0064] The compositions of the present invention may further contain other friction reducing agents besides the (meth)acrylic polymer (A). Examples of other friction reducing agents include oiliness enhancers such as long-chain fatty acid esters and fatty acid amides, anti-wear agents such as phosphate esters and zinc dithiophosphate, extreme pressure agents such as organic sulfur compounds and organic halogen compounds, and friction modifiers such as molybdenum dithiocarbamates.

[0065] The composition of the present invention may be a grease containing a thickener. Examples of thickeners include soap-based (lithium soap, calcium soap, sodium soap, aluminum soap, etc.), inorganic (bentonite, silica gel, etc.), and organic (polyurea, polyurethane, etc.).

[0066] The proportion of (meth)acrylic polymer (A) in the composition of the present invention is preferably 0.01 to 30% by mass, more preferably 0.05 to 25% by mass, and even more preferably 0.1 to 20% by mass, based on the total mass of the composition. If the proportion of (meth)acrylic polymer (A) is above the lower limit of the above numerical range, the friction reduction effect is further improved. If the proportion of (meth)acrylic polymer (A) is below the upper limit of the above numerical range, the viscosity of the composition is easily reduced.

[0067] [Application] The composition of the present invention can be used, for example, as an additive or lubricant composition for lubricating oils used in mobility devices such as automobiles and ships, as well as industrial machinery, robots, etc., such as engine oil, drive system oil (gear oil, transmission oil), hydraulic oil, and metalworking oil.

[0068] Examples of additives for lubricating oils include friction reducers such as oiliness improvers, extreme pressure agents, anti-wear agents, and friction modifiers, as well as antioxidants, viscosity index improvers, pour point depressants, detergent dispersants, corrosion inhibitors, rust inhibitors, defoamers, emulsifiers, antifungal agents, and anti-emulsifiers.

[0069] The composition of the present invention is particularly preferable to be used as a friction reducer for lubricants because it has excellent friction-reducing effects. The lubricant composition of the present invention comprises the composition described above. The lubricant composition may consist only of the composition, or it may further contain components other than the composition (hereinafter also referred to as "optional components") as needed. The content of the composition is preferably 10% by mass or more, more preferably 50% by mass or more, even more preferably 80% by mass or more, and may also be 100% by mass, based on the total mass of the lubricant composition.

[0070] Examples of optional components included in the lubricant composition include those exemplified earlier in the description of the composition. Optional components may be used individually or in combination of two or more. The lubricant composition can be obtained, for example, by mixing the composition with the optional components. Alternatively, the composition may be used as is as the lubricant composition.

[0071] The lubricant composition of the present invention may be a grease containing a thickener. Examples of thickeners include soap-based (lithium soap, calcium soap, sodium soap, aluminum soap, etc.), inorganic (bentonite, silica gel, etc.), and organic (polyurea, polyurethane, etc.).

[0072] The lubricant composition of the present invention can be used, for example, by blending it with engine oil, drivetrain oil (gear oil, transmission oil), hydraulic oil, metalworking oil, etc., used in mobility such as automobiles and ships, as well as industrial machinery, robots, etc. [Examples]

[0073] The embodiments will be described in more detail below with reference to examples, but the present invention is not limited to the following description. In the examples, "parts" refers to "parts by mass". Also, in the table, the content of constituent units derived from each monomer is shown in mass%. The content of each constituent unit was calculated from the mass of each monomer relative to the total mass of monomers used in the polymerization reaction.

[0074] [Abbreviation] • YUBASE4: Base oil manufactured by SK Lubricants • LA: Lauryl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name: LA) • EHA: 2-ethylhexyl acrylate (manufactured by Mitsubishi Chemical Corporation) • MMA: Methyl methacrylate (manufactured by Mitsubishi Chemical Corporation, product name: Acryester M) • 4HBA: 4-Hydroxybutyl acrylate (manufactured by Mitsubishi Chemical Corporation, product name: 4HBA) • M1: Macromonomer (see Manufacturing Example 2 below) • TG: 1-thioglycerol • Nofmer MSD: α-methylstyrene dimer (product of NOF Corporation) • DM: n-dodecyl mercaptan Luperox 575: t-amyl peroxy-2-ethylhexanoate (product of Arkema Yoshitomi Co., Ltd.)

[0075] [Evaluation and Measurement] The evaluation and measurement in this embodiment were carried out by the following method.

[0076] (Molecular weight of macromonomer (M)) The molecular weight of the macromonomer (M) was measured using gel permeation chromatography (GPC) (HLC-8320, manufactured by Tosoh Corporation). Details are as follows.

[0077] A tetrahydrofuran solution (0.2% by mass) of macromonomer (M) was prepared. Then, 10 μL of the tetrahydrofuran solution was injected into an apparatus equipped with columns manufactured by Tosoh Corporation (TSKgel SuperHZM-M (inner diameter 4.6 mm, length 15 cm), HZM-M (inner diameter 4.6 mm, length 15 cm), HZ-2000 (inner diameter 4.6 mm, length 15 cm), and TSKguardcolumn SuperHZ-L (inner diameter 4.6 mm, length 3.5 cm)). Measurements were taken under the following conditions: flow rate: 0.35 ml / min, eluent: tetrahydrofuran (stabilizer BHT), column temperature: 40°C. From the measurement results, Mw, Mn, and molecular weight distribution (Mw / Mn) were calculated in terms of standard polystyrene.

[0078] (Mass-average molecular weight of (meth)acrylic polymers) The molecular weight of the (meth)acrylic polymer was measured using gel permeation chromatography (GPC) (HLC-8320, manufactured by Tosoh Corporation). Details are as follows.

[0079] A tetrahydrofuran solution (0.2% by mass) of a (meth)acrylic polymer was prepared. Then, 10 μL of the tetrahydrofuran solution was injected into an apparatus equipped with two TSKgelSuperHZM-H columns (6.0 mm inner diameter, 15 cm length) and a TSKguardcolumn SuperHZ-H column (4.6 mm inner diameter, 3.5 cm length) manufactured by Tosoh Corporation. Measurements were taken under the following conditions: flow rate 0.5 ml / min, eluent: tetrahydrofuran (stabilizer: BHT), column temperature: 40°C. From the measurement results, the mass-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were calculated in terms of standard polystyrene.

[0080] (B type viscosity) A YUBASE4 solution containing 35% by mass of a (meth)acrylic polymer was used. The B-type viscosity at 25°C was measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd. and TVB10 Viscometer Co., Ltd.) with a rotation speed of 60 rpm and an M2 rotor.

[0081] (Kinematic viscosity (cSt)) A YUBASE4 solution containing 2% by mass of a (meth)acrylic polymer was prepared. The kinematic viscosity at 40°C and 100°C was obtained using a fully automated simple kinematic viscometer (Cannon, product name: Simple-VIS) in accordance with ASTM D7279 (D445).

[0082] (Coefficient of friction) A YUBASE4 solution containing 2% by mass of (meth)acrylic polymer was prepared. The coefficient of friction at 80°C was measured using a UMT TriboLab tester (Brukbr). The measurement conditions were as follows, and the coefficient of friction was evaluated 1000 seconds after the start of measurement.

[0083] Measurement conditions for the coefficient of friction: • Test method: Ball on disc (ball diameter: 10mm, ball and disc material: SUJ2). • Test mode: Rotation (20 mm / s). • Load: 20N.

[0084] (Abrasion mark width) Using the same method as for measuring the coefficient of friction, the disc was cleaned with toluene 3000 seconds after the start of measurement, and the width of the wear marks was measured using a microscope (Nikon ECLIPSE LV100D industrial microscope).

[0085] [Manufacturing Example 1] (Synthesis of Co complexes (cobalt chain transfer agents)) In a synthesis apparatus equipped with a stirring device, 2.00 g (8.03 mmol) of cobalt(II) acetate tetrahydrate (Wako Pure Chemical Industries, Ltd., Wako Special Grade), 3.86 g (16.1 mmol) of diphenylglyoxime (Tokyo Chemical Industries, Ltd., EP Grade), and 100 mL of diethyl ether that had been deoxygenated beforehand by nitrogen bubbling were added under a nitrogen atmosphere, and the mixture was stirred at 25°C for 2 hours. Next, 20 mL of boron trifluoride diethyl ether complex (Tokyo Chemical Industries, Ltd., EP grade) was added, and the mixture was stirred for a further 6 hours. After filtering the resulting solution, the solid was washed with diethyl ether. Subsequently, it was dried at 20°C under a pressure of 100 MPa or less for 12 hours to obtain 5.02 g (7.93 mmol, yield 99% by mass) of the brownish solid Co complex.

[0086] [Manufacturing Example 2] (Synthesis of macromonomer M1) In a reaction vessel equipped with a stirrer, condenser, and thermometer, 58 parts of YUBASE4, 98 parts of Acryester SL (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester SL, a mixture of alkyl methacrylate with 12 C12 alkyl groups and alkyl methacrylate with 13 C13 alkyl groups), 2 parts of MMA, and 0.007 parts of the Co complex obtained in Production Example 1 were added. The liquid temperature was raised to 40°C and dissolved oxygen was removed by bubbling nitrogen over the mixture for 2 hours while stirring. A mixture consisting of 2 parts of YUBASE4 and 0.1 parts of t-amyl peroxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd., trade name: Luperox 575), a polymerization initiator, was added and the liquid temperature was raised to 90°C. After stirring for 2.5 hours, a mixture consisting of YUBASE4 (10 parts) and t-butylperoxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi, trade name: Luperox 26) (0.7 parts) was added dropwise over 1 hour. After the dropwise addition, the temperature was raised to 105°C and held for 1.5 hours. Then, 20 parts of YUBASE4 were added and the mixture was cooled to obtain a YUBASE4 solution containing 52.6% by mass of macromonomer M1. The macromonomer M1 had a Mw of 11,000, a Mn of 5,500, and a Mw / Mn ratio of 2.0.

[0087] [Example 1] Fifty parts of YUBASE4 were added to a reaction vessel equipped with a stirrer, condenser, and thermometer. Dissolved oxygen was removed by bubbling nitrogen while stirring. The liquid temperature was raised to 85°C, and a mixture containing 5 parts of YUBASE4, 30 parts of LA, 60 parts of EHA, 10 parts of MMA, 0.5 parts of Luperox 575 as a polymerization initiator, and 1.9 parts of TG as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (74.8 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic polymer (A-1). The evaluation results are shown in Table 1.

[0088] [Example 2] Fifty parts of YUBASE4 were added to a reaction vessel equipped with a stirrer, condenser, and thermometer. Dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature was raised to 85°C, and a mixture containing 5 parts of YUBASE4, 30 parts of LA, 60 parts of EHA, 10 parts of MMA, 0.5 parts of Luperox 575 as a polymerization initiator, and 1.0 part of TG as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. The temperature was raised to 110°C and held for 1 hour, then YUBASE4 (73 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic polymer (A-2). The evaluation results are shown in Table 1.

[0089] [Example 3] In a reaction vessel equipped with a stirrer, condenser, and thermometer, 27.5 parts of YUBASE4 and 47.5 parts of a YUBASE4 solution containing 52.6% by mass of macromonomer M1 were added. Dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the solution was raised to 85°C, and a mixture containing 5 parts of YUBASE4, 20 parts of LA, 44 parts of EHA, 11 parts of MMA, 0.5 parts of Luperox 575 as a polymerization initiator, and 1.0 part of TG as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (73 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic polymer (A-3). The evaluation results are shown in Table 1.

[0090] [Example 4] Fifty parts of YUBASE4 were added to a reaction vessel equipped with a stirrer, condenser, and thermometer. Dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the liquid was raised to 85°C, and a mixture containing 5 parts of YUBASE4, 30 parts of LA, 60 parts of EHA, 9 parts of MMA, 1 part of 4HBA, 0.5 parts of Luperox 575 as a polymerization initiator, and 1.9 parts of TG as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (74.8 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic polymer (A-4). The evaluation results are shown in Table 1.

[0091] [Example 5] Fifty parts of YUBASE4 were added to a reaction vessel equipped with a stirrer, condenser, and thermometer. Dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the solution was raised to 85°C, and a mixture containing 5 parts of YUBASE4, 30 parts of LA, 60 parts of EHA, 7 parts of MMA, 3 parts of 4HBA, 0.5 parts of Luperox 575 as a polymerization initiator, and 1.9 parts of TG as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (74 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic polymer (A-5). The evaluation results are shown in Table 1.

[0092] [Comparative Example 1] 100 parts of YUBASE4 were added to a reaction vessel equipped with a stirrer, condenser, and thermometer. Dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the solution was raised to 85°C, and a mixture containing 5 parts of YUBASE4, 30 parts of LA, 60 parts of EHA, 10 parts of MMA, 2 parts of Luperox 575 as a polymerization initiator, and 4.0 parts of Nofmer MSD as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (30 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic polymer. The evaluation results are shown in Table 1.

[0093] [Comparative Example 2] Fifty parts of YUBASE4 were added to a reaction vessel equipped with a stirrer, condenser, and thermometer. Dissolved oxygen was removed by bubbling nitrogen while stirring. The temperature of the solution was raised to 85°C, and a mixture containing 5 parts of YUBASE4, 30 parts of LA, 60 parts of EHA, 10 parts of MMA, 0.5 parts of Luperox 575 as a polymerization initiator, and 3.6 parts of DM as a chain transfer agent was added dropwise over 4 hours. After holding at 85°C for 1 hour, a mixture of YUBASE4 (50 parts) and Luperox 575 (0.5 parts) was added dropwise over 1.5 hours. After raising the temperature to 110°C and holding for 1 hour, YUBASE4 (74.8 parts) was added and the mixture was cooled to obtain a YUBASE4 solution containing 35% by mass of (meth)acrylic polymer. The evaluation results are shown in Table 1.

[0094] [Table 1]

[0095] In Examples 1-5, TG was used as the chain transfer agent, resulting in each polymer having a terminal structure in which at least two adjacent carbon atoms are bonded to hydroxyl groups. Examples 1-5 exhibited low coefficients of friction in friction coefficient measurements and excellent friction reduction effects. They also showed small wear marks and excellent wear resistance.

[0096] The polymers of Comparative Examples 1 and 2 have a hydroxyl group content of 0 mmol / g and do not have terminal structures in which hydroxyl groups are bonded to two adjacent carbon atoms. The coefficient of friction measured is high, indicating insufficient friction reduction effect. Furthermore, the width of the wear marks is large, indicating insufficient wear resistance. [Industrial applicability]

[0097] According to the present invention, it is possible to provide a composition, a friction reducing agent, a lubricant composition, and a method for producing a (meth)acrylic polymer that exhibits excellent friction reduction effects and wear resistance.

Claims

1. A composition comprising a (meth)acrylic polymer (A) having a terminal structure in which at least two adjacent carbon atoms are each bonded to a hydroxyl group, and a base oil.

2. A composition comprising a (meth)acrylic polymer (A) having terminal structures derived from a chain transfer agent having two or more hydroxyl groups, and a base oil.

3. The composition according to claim 1 or 2, wherein the (meth)acrylic polymer (A) has a terminal structure derived from thioglycerol.

4. The composition according to claim 1 or 2, wherein the (meth)acrylic polymer (A) has constituent units derived from (meth)acrylate having an alkyl group having 1 to 30 carbon atoms.

5. The composition according to claim 1 or 2, wherein the mass-average molecular weight of the (meth)acrylic polymer (A) is 1,000 to 50,000.

6. The composition according to claim 1 or 2, wherein the hydroxyl group content of the (meth)acrylic polymer (A) is 0.01 to 1.0 mmol / g.

7. A friction reducer containing the composition described in claim 1 or 2.

8. A lubricant composition containing the composition described in claim 1 or 2.

9. A method for producing a (meth)acrylic polymer, comprising polymerizing a mixture containing a chain transfer agent having two or more hydroxyl groups and a (meth)acrylate having an alkyl group having 8 to 30 carbon atoms in a base oil.

10. The manufacturing method according to claim 9, wherein the mixture contains thioglycerol.

11. The aforementioned mixture has a homopolymer SP value of 20.0 (J / cm²). ３ ) １／２ The manufacturing method according to claim 9, comprising a monomer such as the above.

Images