Copolymer, resin composition, lubricant oil additive, lubricant oil, and method for producing lubricant oil additive

Abstract

To provide a copolymer capable of suppressing an exothermic temperature on polymerization, good in solubility to a solvent, and capable of obtaining a lubricant oil exhibiting excellent friction reduction performance.SOLUTION: A copolymer of the present invention has a constitutional unit (a1) derived from a radically polymerizable compound, and a constitutional unit (a2) derived from a non-conjugated olefin, wherein a ratio of the constitutional unit (a2) derived from the non-conjugated olefin is 0.6 to 20 mass% based on the total 100 mass% of all constitutional units of the copolymer. As an example, the radically polymerizable compound may include at least one selected from the group consisting of (meth)acryloyl group-containing compounds and myrcene, and the non-conjugated olefin may include a cyclic monoterpene.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Lubricating oils have been used in internal combustion engines, automatic transmissions, and other machinery to ensure their smooth operation. In recent years, fuel-saving performance requirements for lubricating oils have become increasingly high from the perspective of protecting the global environment, and further improvements in viscosity index, which is one of the indicators of fuel-saving performance, are being sought.

[0003] The copolymer disclosed in Patent Document 1, which comprises structural units derived from a conjugated diene and structural units derived from an aromatic vinyl compound, is used as a viscosity index improver for lubricating oils. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 142001 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the copolymer of Patent Document 1 generates a high heat temperature during polymerization, and there is also room for improvement in solubility in solvents and friction reduction ability. The present invention provides a copolymer that can suppress the temperature at which heat is generated during polymerization, has good solubility in solvents, and can provide a lubricating oil that exhibits excellent friction-reducing properties. [Means for solving the problem]

[0006] The present invention has the following aspects. [1] A copolymer, comprising a structural unit (a1) derived from a radically polymerizable compound and a structural unit (a2) derived from a non-conjugated olefin, A copolymer in which the proportion of the structural units (a2) derived from the non-conjugated olefin is 0.6 to 20% by mass relative to 100% by mass of the total of all structural units of the copolymer. [2] The copolymer according to [1], wherein the non-conjugated olefin comprises a cyclic monoterpene. [3] The copolymer according to [1] or [2], wherein the non-conjugated olefin comprises at least one selected from the group consisting of camphene, limonene, and β-pinene. [4] The copolymer according to any one of [1] to [3], wherein the radical polymerizable compound includes at least one selected from the group consisting of a (meth)acryloyl group-containing compound and myrcene. [5] A resin composition comprising the copolymer according to any one of [1] to [4] and a non-conjugated olefin. [6] The resin composition according to [5], wherein the non-conjugated olefin comprises a cyclic monoterpene. [7] A lubricating oil additive comprising the copolymer according to any one of [1] to [4] and a solvent. [8] A lubricating oil additive comprising the resin composition according to [5] or [6] and a solvent. [9] The lubricating oil additive according to [7] or [8], wherein the average coefficient of friction of the copolymer measured in the following friction coefficient measurement test is 0.180 or less. Friction coefficient measurement test: A solution diluted with mineral oil or synthetic oil so that the copolymer content is 2% by mass is applied to a φ24 x 7.9 mm SUJ-2 disk, and using a vibration friction and wear tester (SRV tester) with a φ10 mm SUJ-2 ball, the friction coefficient is measured at a test temperature of 40°C, an amplitude of 1 mm, and a frequency of 50 Hz, with a load of 50 N for 30 seconds after the start of the test and then a load of 200 N 30 seconds after the start of the test, and the average friction coefficient measured over a test time of 50 to 60 minutes is calculated.

[10] A lubricating oil containing the lubricating oil additive according to any one of [7] to [9].

[0007]

[11] A method for producing a lubricating oil additive, comprising: preparing the copolymer in a solvent; The copolymer has a structural unit (a1) derived from a radically polymerizable compound and a structural unit (a2) derived from a non-conjugated olefin, A method for producing a lubricating oil additive, wherein the proportion of the structural units (a2) derived from the non-conjugated olefin is 0.6 to 20 mass % relative to 100 mass % of the total of all structural units of the copolymer.

[12] The method for producing a lubricating oil additive according to

[11] , wherein the non-conjugated olefin comprises a cyclic monoterpene.

[13] The method for producing a lubricating oil additive according to

[11] or

[12] , wherein the non-conjugated olefin comprises at least one selected from the group consisting of camphene, limonene, and β-pinene. [Effects of the Invention]

[0008] According to the present invention, there is provided a copolymer which can suppress the temperature at which heat is generated during polymerization, has good solubility in solvents, and can provide a lubricating oil which exhibits excellent friction-reducing properties. DETAILED DESCRIPTION OF THE INVENTION

[0009] [term] The meanings of the terms are as follows: The term "structural unit" refers to a unit that constitutes a polymer derived from a monomer, or a structural unit that has been partially converted into a different structure by modifying a polymer. The term "units constituting a polymer derived from a monomer" refers to structural units formed by polymerization of a monomer. "(Meth)acrylate" is a general term for acrylate and methacrylate. "(Meth)acryloyl group" is a general term for acryloyl group and methacryloyl group. "Methacryloyl group" means the portion other than the "R" portion in alkyl methacrylate represented by the following formula (1). "Acryloyl group" means the portion other than the "R" portion in alkyl acrylate represented by the following formula (2).

[0010] [ka]

[0011] The terms "weight average molecular weight" and "number average molecular weight" refer to the weight average molecular weight and number average molecular weight, respectively, measured by gel permeation chromatography (GPC) and converted into standard polystyrene. "Mineral oil" refers to a base oil produced by refining crude oil, such as paraffinic oil or naphthenic oil. "Synthetic oil" means PAO (poly-α-olefin), polybutene, ethylene propylene copolymer (EPO), aliphatic ester, GTL (Gas to Liquid), alkylbenzene, silicone oil, and polyalkylene glycol (PAG).

[0012] "Dissolved" or "soluble" means that when the solution is left to stand at 25°C for one day, no precipitation of insoluble matter or cloudiness of the solution is observed with the naked eye. The symbol "to" indicating a range of values means that the values before and after it are included as the upper and lower limits. The ranges, upper and lower limits of the physical property values disclosed in this specification can be arbitrarily combined to form new ranges of values.

[0013] [Copolymer] The copolymer of the present invention has a structural unit (a1) derived from a radically polymerizable compound and a structural unit (a2) derived from a non-conjugated olefin.

[0014] (Radical polymerizable compound) The copolymer may have the structural unit (a1) derived from one type of radical polymerizable compound, or may have the structural unit (a1) derived from two or more types of radical polymerizable compounds.

[0015] In the copolymer according to one example, the radical polymerizable compound preferably contains at least one selected from the group consisting of a (meth)acryloyl group-containing compound and myrcene. Myrcene is available as a plant-derived monomer, which is desirable from the perspective of building a carbon-recycling society. The plant-derived monomer can be confirmed by measuring its radioactive carbon concentration.

[0016] Examples of the (meth)acryloyl group-containing compound include, but are not limited to, various (meth)acryloyl group-containing compounds such as alkyl (meth)acrylate, (meth)acrylic acid, (meth)acrylamide, polyalkylene glycol (meth)acrylate, hydroxyalkyl (meth)acrylate, alkylsilyloxy (meth)acrylate, alkoxysilylalkyl (meth)acrylate, alkenyl (meth)acrylate, glycidyl (meth)acrylate, fluoroalkyl (meth)acrylate, and (meth)acryloylalkyl acid phosphate.

[0017] Examples of the (meth)acryloyl group-containing compound include (meth)acrylates of linear or branched alkyl alcohols such as ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, and tridecyl (meth)acrylate; (Meth)acrylates of cyclic alkyl alcohols such as cyclohexyl (meth)acrylate; (meth)acrylates containing a terminal hydroxy group and / or an ether group, such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene glycol-propylene glycol-mono(meth)acrylate, polyethylene glycol-tetramethylene glycol-mono(meth)acrylate, polypropylene glycol-polybutylene glycol-mono(meth)acrylate, methoxypolyethylene glycol monomethacrylate, methoxypolypropyl glycol monomethacrylate, glycerin mono(meth)acrylate, 4-hydroxybutyl (meth)acrylate, and hydroxyethyl (meth)acrylate; (meth)acrylates containing a silyloxy group, such as 2-(trimethylsilyloxy)(meth)acrylate, 3-(methyldimethoxysilyl)propyl(meth)acrylate, 3-(methoxysilyl)propyl(meth)acrylate, 3-(triethoxysilyl)propyl(meth)acrylate, and 3-(trimethoxysilyl)propyl(meth)acrylate; (Meth)acrylates containing a vinyl group, such as allyl (meth)acrylate; Di(meth)acrylates such as 1,3-butanediol di(meth)acrylate; (Meth)acrylates having an amino group, such as 2-(dimethylamino)ethyl (meth)acrylate and diethylacrylamide; (Meth)acrylates having a carboxylic acid group such as (meth)acrylic acid; (meth)acrylates having an epoxy group, such as glycidyl (meth)acrylate; (meth)acrylates having a fluoroalkyl group, such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,2H,2H-tridecafluorooctyl acrylate, and 2,2,2-trifluoroethyl; Examples thereof include (meth)acrylates having a phosphoric acid group such as 2-methacryloyloxyethyl acid phosphate and 2-methacryloyloxyethyl acid phosphate.

[0018] From the viewpoint of improving the friction reducing ability, the upper limit of the carbon number of the (meth)acryloyl group-containing compound is preferably not more than 65, more preferably not more than 60. On the other hand, from the viewpoint of improving the solubility in oil, the lower limit of the carbon number of the (meth)acryloyl group-containing compound is preferably not less than 3, more preferably not less than 4.

[0019] From the viewpoint of improving friction reducing ability, the (meth)acryloyl group-containing compound preferably has at least one functional group selected from the group consisting of an alkyl group, a hydroxyl group, a silyloxy group, a vinyl group, an ether group, an amino group, a carboxylic acid group, an epoxy group, a fluorine atom, and a phosphate group, and among these, at least one functional group selected from the group consisting of an alkyl group, a hydroxyl group, a silyloxy group, a vinyl group, an ether group, an amino group, a carboxylic acid group, a fluorine atom, and a phosphate group is preferred.

[0020] In the case of alkyl (meth)acrylate, the number of carbon atoms in the alkyl group in the alkyl (meth)acrylate is preferably 1 to 60, more preferably 2 to 55. The "alkyl group" here means a C n H 2n+1 - is a functional group that can be represented by the formula: n is an integer of 1 to 60. n is preferably 2 to 60 from the viewpoint of improving solubility in oil.

[0021] The (meth)acryloyl group-containing compound may be used alone or in combination of two or more kinds.

[0022] (non-conjugated olefin) The copolymer may have structural units (a2) derived from one type of non-conjugated olefin, or may have structural units (a2) derived from two or more types of non-conjugated olefins. Examples of non-conjugated olefins include cyclic monoterpenes and α-olefins. Cyclic monoterpenes are preferred in that they can further suppress heat generation during polymerization.

[0023] Examples of cyclic monoterpenes include limonene, camphene, α-pinene, β-pinene, and sabinene. Among these, limonene, camphene, and β-pinene are preferred, and limonene is more preferred, in terms of being able to further suppress heat generation during polymerization. The cyclic monoterpenes may be used alone or in combination of two or more.

[0024] (other monomers) The copolymer may further contain a structural unit (a3) derived from a monomer other than the radical polymerizable compound and the non-conjugated olefin, as long as the effects of the invention are not impaired. The other monomer may be used alone or in combination of two or more.

[0025] Other monomers include, for example, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile; vinyl ether monomers such as vinyl methyl ether and vinyl ethyl ether; carboxylic acid-based vinyl monomers such as vinyl acetate and vinyl butyrate; olefinic monomers such as ethylene, propylene, and isobutylene; Vinyl halide monomers such as vinyl chloride and vinylidene chloride; Examples include maleimide-based monomers such as maleimide, N-phenylmaleimide, N-cyclohexylmaleimide, and N-methylmaleimide.

[0026] (Copolymer composition) The proportion of the structural unit (a1) derived from the radical polymerizable compound is preferably 80 to 99.4 mass%, more preferably 85 to 99 mass%, and even more preferably 89 to 96 mass%, based on 100 mass% of the total of all structural units of the copolymer. When the proportion of the structural unit (a1) derived from the radical polymerizable compound is at least the lower limit of the above-mentioned numerical range, solubility in solvents is likely to be improved. When the proportion of the structural unit (a1) derived from the radical polymerizable compound is at most the upper limit of the above-mentioned numerical range, friction reduction ability is likely to be improved.

[0027] The proportion of the structural units (a2) derived from non-conjugated olefin is 0.6 to 20 mass%, preferably 1 to 15 mass%, more preferably 3 to 13 mass%, and even more preferably 4 to 11 mass%, relative to 100 mass% of the total of all structural units in the copolymer. When the proportion of the structural units (a2) derived from non-conjugated olefin is at least the lower limit of the above-mentioned numerical range, friction reduction ability is likely to be improved. When the proportion of the structural units (a2) derived from non-conjugated olefin is at most the upper limit of the above-mentioned numerical range, solubility in solvents is likely to be improved.

[0028] When the copolymer contains structural units (a3) derived from other monomers, the proportion of the structural units (a3) derived from other monomers is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 10% by mass or less, based on 100% by mass of the total of all structural units of the copolymer. When the proportion of the structural units (a3) derived from other monomers is equal to or less than the upper limit of the aforementioned range, the effects of the invention are less likely to be impaired.

[0029] (Properties of copolymer) The weight-average molecular weight of the copolymer is preferably 5,000 to 500,000, more preferably 8,000 to 300,000, and even more preferably 10,000 to 250,000. When the weight-average molecular weight of the copolymer is equal to or greater than the lower limit of the above-mentioned range, the viscosity index is likely to be improved. When the weight-average molecular weight of the copolymer is equal to or greater than the lower limit of the above-mentioned range, the solubility in solvents is likely to be improved.

[0030] The number average molecular weight of the copolymer is preferably 3,000 to 50,000, more preferably 5,000 to 40,000, and even more preferably 10,000 to 30,000. When the number average molecular weight of the copolymer is equal to or greater than the lower limit of the above-mentioned range, the viscosity index is likely to be improved. When the number average molecular weight of the copolymer is equal to or greater than the lower limit of the above-mentioned range, the solubility in solvents is likely to be improved.

[0031] The average value of the friction coefficient of the copolymer measured in the following friction coefficient measurement test is preferably 0.180 or less, more preferably 0.175 or less, and even more preferably 0.170 or less. If the friction coefficient of the copolymer is the above upper limit value or less, it can be said that the friction reducing ability is excellent. Friction coefficient measurement test: A solution diluted with mineral oil or synthetic oil so that the copolymer content is 2% by mass is applied to a φ24 x 7.9 mm SUJ-2 disk, and using a vibration friction and wear tester (SRV tester) with a φ10 mm SUJ-2 ball, the friction coefficient is measured at a test temperature of 40°C, an amplitude of 1 mm, and a frequency of 50 Hz, with a load of 50 N for 30 seconds after the start of the test, and then with a load of 200 N 30 seconds after the start of the test, and the average friction coefficient measured over a test time of 50 to 60 minutes is calculated.

[0032] (Method for producing copolymer) The copolymer is not particularly limited, and can be produced, for example, by polymerizing a monomer component containing a radical polymerizable compound and a non-conjugated olefin. The monomer component may further contain a monomer other than the radical polymerizable compound and the non-conjugated olefin, as necessary. The details and preferred aspects of the composition of the monomer component are the same as those described for the copolymer composition.

[0033] The method for polymerizing the monomer components is not particularly limited. Examples include various polymerization methods such as solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. Among these, solution polymerization using a solvent is preferred. The solvent will be described later.

[0034] A polymerization initiator may be used for the polymerization. One radical polymerization initiator may be used alone, or two or more radical polymerization initiators may be used in combination. Examples of the radical polymerization initiator include organic peroxides and azo compounds.

[0035] Suitable organic peroxides include, for example, organic peroxides and azo compounds. Examples of organic peroxides include t-butyl peroxypivalate, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, cyclohexanone peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butylperoxy-2-ethylhexanoate, and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate. Examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile).

[0036] The polymerization temperature is preferably 40 to 150°C, more preferably 80 to 130°C. The polymerization time is preferably 1 to 24 hours, more preferably 5 to 15 hours.

[0037] [Resin composition] The resin composition contains the copolymer according to the present embodiment and a non-conjugated olefin. Details and preferred embodiments of the copolymer have been described above. Details and preferred embodiments of the non-conjugated olefin have also been described above.

[0038] The resin composition may contain one type of copolymer according to this embodiment, or may contain two or more types of copolymers according to this embodiment. In addition, the resin composition may contain one type of non-conjugated olefin, or may contain two or more types of non-conjugated olefins.

[0039] The resin composition may further contain other components in addition to the copolymer according to this embodiment and the non-conjugated olefin, as long as the effects of the invention are not impaired. The other components may be used alone or in combination of two or more thereof, and examples of the other components include detergents, dispersants, antioxidants, oiliness improvers, friction and wear modifiers, extreme pressure agents, antifoaming agents, demulsifiers, corrosion inhibitors, pour point depressants, rust inhibitors, emulsifiers, and fungicides.

[0040] The content of the copolymer according to this embodiment in the resin composition is preferably 10 to 99.9% by mass, more preferably 40 to 99% by mass, and even more preferably 60 to 90% by mass, relative to 100% by mass of the total amount of the resin composition. When the content of the copolymer according to this embodiment is equal to or greater than the lower limit of the above-mentioned range, friction reduction ability is likely to be improved. When the content of the copolymer according to this embodiment is equal to or less than the upper limit of the above-mentioned range, solubility in solvents is likely to be improved.

[0041] The content of the non-conjugated olefin in the resin composition is preferably 0.1 to 90% by mass, more preferably 1 to 60% by mass, and even more preferably 10 to 40% by mass, relative to 100% by mass of the total amount of the resin composition. When the content of the non-conjugated olefin is equal to or greater than the lower limit of the above-mentioned numerical range, heat generation during polymerization is more easily suppressed. When the content of the non-conjugated olefin is equal to or less than the upper limit of the above-mentioned numerical range, friction reduction ability is easily improved. Furthermore, solubility in solvents is easily improved.

[0042] When the resin composition further contains other components, the content of the other components is preferably 0.1 to 99.9% by mass, more preferably 1 to 50% by mass, and even more preferably 2 to 30% by mass, relative to 100% by mass of the total amount of the resin composition. If the content of the other components is equal to or greater than the lower limit of the above-mentioned numerical range, the properties of the other components can be easily imparted. If the content of the other components is equal to or less than the upper limit of the above-mentioned numerical range, the effects of the invention are less likely to be impaired.

[0043] [Lubricant additives] A lubricating oil additive according to one example contains the copolymer according to the present embodiment and a solvent. Details and preferred embodiments of the copolymer have been described above. The lubricating oil additive may contain one type of copolymer according to the present embodiment, or may contain two or more types of copolymers according to the present embodiment.

[0044] The solvent may be used alone or in combination of two or more thereof. Examples of the solvent include base oils such as paraffinic oil, naphthenic oil, and aromatic oil. In terms of compatibility with lubricating oil additives, base oils such as paraffinic oils, naphthenic oils, and aromatic oils are preferred.

[0045] The base oil may be a mineral oil or a synthetic oil. The base oil may be a commercially available product, for example, an API Group III base oil such as YUBASE3 manufactured by SK Lubricants, an API Group III plus base oil such as YUBASE4 manufactured by SK Lubricants, or a poly-α-olefin such as DURASYN170 manufactured by INEOS Oligomers. The solvent may be used alone or in combination of two or more.

[0046] The lubricating oil additive may further contain other components in addition to the copolymer according to this embodiment and the solvent, as long as the effects of the invention are not impaired. The other components may be used alone or in combination of two or more thereof, and examples of the other components include detergents, dispersants, antioxidants, oiliness improvers, friction and wear modifiers, extreme pressure agents, antifoaming agents, demulsifiers, corrosion inhibitors, pour point depressants, rust inhibitors, emulsifiers, and fungicides.

[0047] The content of the copolymer according to this embodiment in the lubricating oil additive is preferably 0.1 to 99.9% by mass, more preferably 1 to 90% by mass, and even more preferably 2 to 70% by mass, relative to 100% by mass of the total amount of the lubricating oil additive. When the content of the copolymer according to this embodiment is equal to or greater than the lower limit of the above-mentioned range, friction reduction ability is likely to be improved. When the content of the copolymer according to this embodiment is equal to or less than the upper limit of the above-mentioned range, solubility in solvents is likely to be improved.

[0048] When the lubricating oil additive further contains other components, the content of the other components is preferably 0.01 to 99.9 mass%, more preferably 0.05 to 80 mass%, and even more preferably 0.1 to 60 mass%, relative to 100 mass% of the total amount of the lubricating oil additive. If the content of the other components is equal to or greater than the lower limit of the above-mentioned range, the properties of the other components are easily imparted. If the content of the other components is equal to or less than the upper limit of the above-mentioned range, the effects of the invention are less likely to be impaired.

[0049] Another example of a lubricating oil additive contains the resin composition according to the present embodiment and a solvent. Details and preferred aspects of the resin composition and the solvent are as already described.

[0050] [Lubricant additive manufacturing method] The method for producing the lubricating oil additive includes producing the copolymer according to the present embodiment described above in a solvent. The details and preferred aspects of the copolymer and solvent according to this embodiment have been described above, and the method for producing the copolymer has also been described above.

[0051] [Lubricating oil] The lubricating oil contains the lubricating oil additive according to the present embodiment described above. The lubricating oil may contain one type of lubricating oil additive according to the present embodiment, or may contain two or more types of lubricating oil additives according to the present embodiment. Examples of the solvent for the lubricating oil include base oils such as paraffinic oils, naphthenic oils, and aromatic oils. In terms of compatibility with lubricating oil additives, base oils such as paraffinic oils, naphthenic oils, and aromatic oils are preferred.

[0052] The base oil may be a mineral oil or a synthetic oil. The base oil may be a commercially available product, for example, an API Group III base oil such as YUBASE3 manufactured by SK Lubricants, an API Group III plus base oil such as YUBASE4 manufactured by SK Lubricants, or a poly-α-olefin such as DURASYN170 manufactured by INEOS Oligomers. The solvent may be used alone or in combination of two or more.

[0053] The content of the lubricating oil additive according to this embodiment in the lubricating oil is preferably 0.01 to 50 mass%, more preferably 0.05 to 30 mass%, and even more preferably 0.1 to 20 mass%, relative to 100 mass% of the total amount of the lubricating oil. When the content of the lubricating oil additive according to this embodiment is equal to or greater than the lower limit of the above-mentioned range, friction reducing ability is likely to be improved. When the content of the lubricating oil additive according to this embodiment is equal to or less than the upper limit of the above-mentioned range, solubility in solvents is likely to be improved.

[0054] The lubricating oil may be a grease containing a thickener, such as a soap-based thickener (lithium soap, calcium soap, sodium soap, aluminum soap, etc.), an inorganic thickener (bentonite, silica gel, etc.), or an organic thickener (polyurea, polyurethane, etc.).

[0055] [Application] Examples of uses include various lubricating oils such as engine oil, gear oil, hydraulic oil, drive system lubricating oil, and automatic transmission oil used in industrial machinery, robots, automobiles, and other mobility applications. [Example]

[0056] Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following descriptions. In the following, "parts" means "parts by mass" unless otherwise specified.

[0057] [Measurement and evaluation methods] (coefficient of friction) The content of each structural unit was calculated from the amount of monomer charged. The content of structural unit (a1) relative to 100% by mass of all structural units in the copolymer was calculated from the amount of radically polymerizable compound charged. The content of structural unit (a2) relative to 100% by mass of all structural units in the copolymer was calculated from the amount of non-conjugated olefin charged.

[0058] (polymerization heat generation temperature) A thermocouple was inserted into the Schlenk tube containing the polymerization raw materials, and the internal temperature before the start of polymerization was measured. After the polymerization initiator was added, internal temperature measurement began, and the maximum internal temperature within 15 minutes of the start of polymerization was recorded. The polymerization exothermic temperature was calculated as (maximum internal temperature within 15 minutes of the start of polymerization) - (internal temperature before the start of polymerization).

[0059] (polymerization conversion rate) A portion of the reaction mixture before and after the polymerization was measured by gas chromatography. The polymerization conversion rate was determined by calculating the amount of monomer remaining in the reaction mixture after the polymerization.

[0060] (Solubility) The copolymer solution was further diluted with a dilution solvent so that the copolymer concentration was 5% by mass, and the resulting solution was visually inspected. The solubility of the copolymer was evaluated according to the following evaluation criteria. ◯: The solution is clear. ×: The solution is opaque or insoluble matter is precipitated.

[0061] (coefficient of friction) A solution diluted with lubricating base oil (manufactured by SK Lubricants Co., Ltd., trade name: YUBASE4) so that the copolymer content was 2% by mass was applied to the disk. The friction coefficient was measured under the ball-on-disk test conditions using the measuring equipment listed below. The average value of the friction coefficients measured between 50 and 60 minutes after the start of the test was taken as the friction coefficient. Measuring equipment: vibration friction and wear tester (SRV tester) Disc: SUJ-2, φ24mm x 7.9mm Ball: SUJ-2, φ10mm ·Temperature: 40℃ Load: 50N for 30 seconds from the start of the test. 200N after 0 seconds. ·Amplitude: 1mm Frequency: 50Hz Test duration: 60 minutes

[0062] [Example 1] A dried Schlenk flask was charged with 33.30 parts by mass of lubricating base oil (SK Lubricants Co., Ltd., trade name: YUBASE4), 20.00 parts by mass of Blenmar PP-800 (NOF Corporation), 71.23 parts by mass of Myrcene (Yasuhara Chemical Co., Ltd.), 5.98 parts by mass of limonene, 0.90 parts by mass of β-pinene, and 1.89 parts by mass of camphene. The atmosphere inside the Schlenk flask was thoroughly purged with nitrogen, and the temperature was raised to 100°C. Next, 7.10 parts by mass of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (NOF Corporation, trade name: Perocta 0) was added as a polymerization initiator, and the reaction was allowed to proceed for 10 hours. The resulting polymerized solution was used as a lubricating oil additive and subjected to the various evaluations described above. The evaluation results are shown in Table 1.

[0063] Blemmer PP-800 is polypropylene glycol monomethacrylate, a compound represented by the following formula (3).

[0064] [ka]

[0065] [Examples 2-4, Comparative Examples 1-3] A polymerization solution was obtained in the same manner as in Example 1, except that the types and amounts of the radical polymerizable compound and non-conjugated olefin used were changed as shown in Table 1. The evaluation results are shown in Table 1.

[0066] [Table 1]

[0067] SLMA: (manufactured by Mitsubishi Chemical Corporation, trade name: Acryester SL, a mixture of alkyl methacrylate with an alkyl group having 12 carbon atoms and alkyl methacrylate with an alkyl group having 13 carbon atoms).

[0068] In Examples 1-4, the polymerization heat generation temperature was low, and the temperature during polymerization was suppressed. In addition, the solubility evaluation was also good, and the solubility in solvents was good. Furthermore, it was found that the friction coefficient was low, and excellent friction reduction ability was exhibited.

[0069] In Comparative Example 1, the coefficient of friction could not be measured due to the low polymerization rate, and in Comparative Example 2, the coefficient of friction could not be measured due to the extremely poor solubility in oil. [Industrial Applicability]

[0070] According to the present invention, there is provided a copolymer which can suppress the temperature at which heat is generated during polymerization, has good solubility in solvents, and can provide a lubricating oil which exhibits excellent friction-reducing properties.

Claims

1. A copolymer, The copolymer has a structural unit (a1) derived from a radically polymerizable compound and a structural unit (a2) derived from a non-conjugated olefin, A copolymer in which the proportion of the structural units (a2) derived from the non-conjugated olefin is 0.6 to 20% by mass, relative to 100% by mass of the total of all structural units of the copolymer.

2. The copolymer of claim 1 , wherein the non-conjugated olefin comprises a cyclic monoterpene.

3. 2. The copolymer according to claim 1, wherein the non-conjugated olefin comprises at least one selected from the group consisting of camphene, limonene, and β-pinene.

4. The copolymer according to claim 1 , wherein the radical polymerizable compound comprises at least one selected from the group consisting of a (meth)acryloyl group-containing compound and myrcene.

5. A resin composition comprising the copolymer according to claim 1 and a non-conjugated olefin.

6. The resin composition of claim 5 , wherein the non-conjugated olefin comprises a cyclic monoterpene.

7. A lubricating oil additive comprising the copolymer according to claim 1 and a solvent.

8. A lubricating oil additive comprising the resin composition according to claim 5 and a solvent.

9. 8. The lubricating oil additive according to claim 7, wherein the copolymer has an average coefficient of friction of 0.180 or less as measured in the following friction coefficient measurement test. Friction coefficient measurement test: A solution diluted with mineral oil or synthetic chemical oil so that the copolymer content is 2% by mass is applied to a φ24×7.9 mm SUJ-2 disk, and the friction coefficient is measured using a vibration friction and wear tester (SRV tester) with a φ10 mm SUJ-2 ball under conditions of a test temperature of 40°C, an amplitude of 1 mm, and a frequency of 50 Hz, with a load of 50 N for 30 seconds after the start of the test and a load of 200 N 30 seconds after the start of the test, and the average value of the friction coefficients measured over a test time of 50 to 60 minutes is calculated.

10. A lubricating oil containing the lubricating oil additive according to any one of claims 7 to 9.

11. 1. A method for producing a lubricating oil additive, comprising: preparing the copolymer in a solvent; The copolymer has a structural unit (a1) derived from a radically polymerizable compound and a structural unit (a2) derived from a non-conjugated olefin, The method for producing a lubricating oil additive, wherein the proportion of the structural units (a2) derived from the non-conjugated olefin is 0.6 to 20 mass% relative to 100 mass% of the total of all structural units of the copolymer.

12. 12. The method of making a lubricating oil additive of claim 11, wherein the non-conjugated olefin comprises a cyclic monoterpene.

13. The method for producing a lubricating oil additive according to claim 11, wherein the non-conjugated olefin comprises at least one selected from the group consisting of camphene, limonene, and β-pinene.

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