Hyperbranched polymer, method for producing the same, additive for lubricating oil, and lubricating oil composition

Abstract

To provide a hyperbranched polymer that can produce a lubricating oil composition with low viscosity and excellent friction reduction effect. [Solution] The hyperbranched polymer is an atom transfer radical polymer of (A) an alkyl (meth)acrylate and (B) a compound having a (meth)acrylate group and a halogenated functional group.

Description

[Technical Field]

[0001] This invention relates to a hyperbranched polymer, a method for producing the same, an additive for lubricating oils, and a lubricating oil composition. [Background technology]

[0002] Traditionally, lubricant additives have been used to improve the lubrication performance of lubricants. Furthermore, in recent years, there has been a growing demand for even greater energy efficiency from lubricants, particularly from the perspective of reducing CO2 emissions. In automotive applications, in particular, the shift from gasoline-powered vehicles to hybrid and battery-electric vehicles is causing a decrease in the temperature of combustion engines and powertrains. This raises concerns that the effectiveness of conventional inorganic extreme-pressure additives, which generate reaction films at high temperatures and high energy to reduce friction, will diminish.

[0003] Against this backdrop, polymer-based additives that can exert relatively strong physical adsorption even at low temperatures are attracting attention as lubricant additives.

[0004] For example, Non-Patent Document 1 describes that low molecular weight oleic acid adsorbent polymers are used as lubricant additives.

[0005] Non-patent document 2 describes the use of polyalkyl methacrylate as an adsorption polymer that offers a high degree of freedom in molecular design and excellent oil film-forming ability. It is stated that the physical properties of the adsorption polymer described in Non-patent document 2 can be optimized by adjusting the chain length and polar groups of the polymer.

[0006] Patent documents 1 and 3 describe copolymers of methyl methacrylate, lauryl methacrylate, and stearyl methacrylate produced by living anionic polymerization. These polymers have enhanced friction-reducing effects by controlling polar groups in a specific arrangement as block copolymers. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2023-58049 [Non-patent literature]

[0008] [Non-Patent Document 1] Koji Takiwatari, Hidetaka Nanao, Ichiro Minami, and Masayuki Mori: Interaction between oleic acid and base oil under elastofluid lubrication, Tribologist, Vol. 54, No. 1 (2009), pp. 48-53. [Non-Patent Document 2] Kenta Nakamura, Masayoshi Muraki: Effects of alkyl group and molecular weight of polyalkyl methacrylate on oil film-forming ability, Tribologist, Vol. 52, No. 9 (2007), pp. 687-695. [Non-Patent Document 3] Kenta Nakamura, Masayoshi Muraki, Takefumi Narita, Kosei Hayashi, and Toru Takahashi: Tribological properties of methyl methacrylate copolymers, Tribologist, Vol. 68, No. 10 (2023), pp. 713-726. [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the linear low molecular weight polymer described in Non-Patent Document 1 has a relatively simple molecular structure and limited oil film stability, and therefore was not entirely satisfactory in terms of improving lubricity.

[0010] Furthermore, since the polymers described in Non-Patent Documents 2 and 3 and Patent Document 1 are linear polymers, the linear influence is significant, and aggregation due to intermolecular entanglement is likely to occur. For this reason, lubricating oils to which these linear polymers are added tend to change viscosity with temperature, and the increase in viscosity, especially at low temperatures, inhibits fluidity and reduces energy efficiency.

[0011] Furthermore, while lower viscosity lubricants are desired from the perspective of energy efficiency, generally speaking, while lowering the viscosity of a lubricant contributes to reducing friction in the fluid lubrication region, it increases the coefficient of friction in the boundary lubrication region where the contact resistance between two objects is high. In other words, with conventional lubricants containing additives (such as linear polymers), it has been difficult to achieve both low viscosity and friction reduction effects.

[0012] This invention has been made in view of the above circumstances, and aims to provide a lubricating oil additive that can produce a lubricating oil composition that is lower in viscosity and has a superior friction-reducing effect compared to conventional lubricating oils, and a lubricating oil composition containing the same. It also aims to provide a novel hyperbranched polymer that constitutes the lubricating oil additive and a method for producing the same. [Means for solving the problem]

[0013] To solve the above problems, the following hyperbranched polymer, a method for producing the same, a lubricant additive, and a lubricant composition are provided. [1] (A) alkyl (meth)acrylate, (B) Compounds having a (meth)acrylate group and a halogenated functional group A hyperbranched polymer, which is an atom-transfer radical polymer. [2] The hyperbranched polymer of compound (A) wherein the alkyl group has 6 to 18 carbon atoms. [3] The hyperbranched polymer of [1] or [2], wherein the halogenated functional group is a 2-halo-2-methylpropanoyl group. [4] The hyperbranched polymer of [1] or [2], wherein compound (B) is 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl acrylate or 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl methacrylate). [5] A hyperbranched polymer according to any of [1] to [4], wherein the content of compound (A) is 1 to 30 mol%. [6] The hyperbranched polymer according to any one of [1] to [5], wherein the content of the compound (B) is 0.1 to 50 mol%. [7] The hyperbranched polymer according to any one of [1] to [6], having a number average molecular weight (Mn) of 5000 to 50000. [8] The hyperbranched polymer according to any one of [1] to [7], having a molar branching degree of 1 to 50 mol%. [9] The hyperbranched polymer according to any one of [1] to [8], having a molecular weight distribution (Mw / Mn) of 1.0 to 3.8.

[10] (A) Alkyl (meth)acrylate, and (B) A compound having a (meth)acrylate group and a halogenated functional group A method for producing a hyperbranched polymer, comprising a polymerization step of subjecting the above to atom transfer radical polymerization.

[11] An additive for lubricating oil, comprising the hyperbranched polymer according to any one of [1] to [9].

[12] A lubricating oil composition, comprising a base oil and the additive for lubricating oil according to

[11] . [Effect of the Invention]

[0014] The lubricating oil composition of the present invention has a lower viscosity and an excellent friction reduction effect as compared with conventional lubricating oils. By adding the additive for lubricating oil of the present invention to a base oil, a lubricating oil composition having a lower viscosity and an excellent friction reduction effect can be obtained. The hyperbranched polymer of the present invention is used as an additive for lubricating oil. According to the method for producing a hyperbranched polymer of the present invention, a hyperbranched polymer can be easily produced. [Brief Description of the Drawings]

[0015] [Figure 1] It is a diagram showing an example of the method for producing a hyperbranched polymer of the present invention. [Figure 2] It is a diagram showing 13C-NMR spectra of the synthetic polymers of Examples 1-3 and Comparative Example 1. [Figure 3]This figure shows the change in the coefficient of friction with respect to sliding speed for the sample oils (Table 1) of Examples 4-6 and Comparative Examples 2 and 5. [Figure 4] This figure shows the time variation of friction at a sliding velocity of 0.1 m / s for the sample oils (Table 1) of Examples 4-6 and Comparative Examples 2 and 5. [Modes for carrying out the invention]

[0016] The following describes one embodiment of the hyperbranched polymer of the present invention, its manufacturing method, a lubricating oil additive, and a lubricating oil composition.

[0017] <Hyperbranched polymer> Hyperbranched polymers are polymers that have repeating units, possess dendritic branching in their structure, and also have unbranched regions.

[0018] The hyperbranched polymer of the present invention is oil-soluble. Furthermore, due to its branched structure (hyperbranch structure), the hyperbranched polymer of the present invention suppresses entanglement between polymers in oil. For this reason, by adding the hyperbranched polymer of the present invention to a base oil as a lubricant additive, a lubricant composition with low viscosity and excellent friction reduction effect can be obtained.

[0019] Specifically, the hyperbranched polymer of the present invention is (A) Alkyl (meth)acrylate, and (B) Compounds having a (meth)acrylate group and a halogenated functional group It is an atom-transfer radical polymer.

[0020] In this invention, "(meth)acrylate" means acrylate and / or methacrylate.

[0021] The alkyl(meth)acrylate (compound (A)) preferably has 6 to 18 carbon atoms in the alkyl group. When the number of carbon atoms in the alkyl group is within this range, the lubricating oil composition obtained by adding the hyperbranched polymer has low viscosity and excellent friction reduction effect.

[0022] Compound (B) only needs to have a (meth)acrylate group and a halogenated functional group, and its specific structure is not particularly limited.

[0023] Examples of halogenated functional groups in compound (B) include halogenated alkyl groups, halogenated ester groups, halogenated acyl groups, halogenated carboxylic acid groups, halogenated nitrile groups, and halogenated ketone groups.

[0024] Examples of halogens in halogenated functional groups include Br, Cl, and I.

[0025] The halogenated functional group of compound (B) above is a structure derived from an initiator (halogenated organic compound) for atom transfer radical polymerization (ATRP). In this case, conventionally known compounds are preferably used as initiators for atom transfer radical polymerization (ATRP), such as ethyl bromoacetate, methyl bromoacetate, 2-bromoisobutyric acid, ethyl 2-bromoisobutyrate, 2-bromoisobutyryl bromide, allyl bromide, ethyl 2-bromopropionate, methyl 2-bromopropionate, tert-butyl 2-bromoisobutyrate, [11-[(2-bromo-2-methylpropanoyl)oxy]undecyl]phosphonic acid, and methyl chloroacetate. , chloroacetonitrile, (R)-(+)-2-methyl chloropropionate, (S)-(-)-2-methyl chloropropionate, 2-chloropropanenitrile, 2-bromo-2-methylmalonate diethyl, 2-chloro-2-phenyl ethyl acetate, 2-bromo-2-phenyl ethyl acetate, α-bromophenylacetate methyl, bromoacetonitrile, 2-bromopropionate tert-butyl, (1-chloroethyl)benzene, 2-chloropropionate ethyl, 2,2-di Chloroacetophenone, ethyl 2-iodopropionate, 2-hydroxyethyl 2-bromo-2-methylpropanoate, 3-(trimethoxysilyl)propyl 2-bromo-2-methylpropanoate, (1-bromoethyl)benzene, 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl acrylate, 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl methacrylate (BIBEM), methyl 2-chloropropionate, 2-bromo-2-methylpropionate Examples include 2-[(2-hydroxyethyl)disulfanyl]ethyl ionic acid, 11-mercaptoundecyl 2-bromo-2-methylpropanoate, pentaerythritol tetrakis(2-bromoisobutyrate), 2-bromo-2-methylpropanoate 2-propyne-1-yl, 2-bromo-2-methylpropanoate 3-(trichlorosilyl)propyl, 2-bromo-2-methylpropanoate 3-(triethoxysilyl)propyl, and diethyl bromomalonate.

[0026] Of the initiators mentioned above, 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl acrylate and 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl methacrylate (BIBEM) have a 2-bromo-2-methylpropanoyl group as a halogenating functional group, as well as an acrylate group or a methacrylate group. Therefore, as compound (B), 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl acrylate or 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl methacrylate (BIBEM) can be preferably exemplified. Furthermore, these initiators may also be in a form in which bromine (Br) is substituted with another halogen. That is, the halogenating functional group may also preferably be a 2-halo-2-methylpropanoyl group.

[0027] On the other hand, initiators other than 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl acrylate and 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl methacrylate (BIBEM) can be used as compound (B) by attaching a (meth)acrylate group.

[0028] Compound (B) may be in a form in which the (meth)acrylate group and the halogenated functional group are directly bonded. Alternatively, compound (B) may be in a form in which an organic group is interposed between the (meth)acrylate group and the halogenated functional group. (meth)acrylate group-organic group-halogenated functional group That's fine.

[0029] In the latter form, the organic group is not particularly limited, but examples include aliphatic groups, aromatic groups, and carbon groups containing heteroatoms. Specifically, in one form of the hyperbranched polymer of the present invention, examples of organic groups include alkylene groups, phenylene groups, naphthylene groups, and derivatives thereof having substituents. Examples of heteroatoms include nitrogen (N), oxygen (O), sulfur (S), phosphorus (P), chlorine (Cl), iodine (I), and bromine (Br).

[0030] The alkylene group is not particularly limited, but it is preferably a linear or branched alkylene group having 1 to 8 carbon atoms. Specifically, examples include a methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, etc. These alkylene groups may contain nitrogen atoms, oxygen atoms, sulfur atoms, etc., and may be mediated via a phenylene group.

[0031] Furthermore, the organic group may have substituents on any carbon atom. Examples of substituents include halogen atoms, hydroxyl groups, primary to tertiary amino groups, quaternary ammonium groups, ether groups, C2-C4 polyalkylene glycol groups, carbonyl groups, carboxyl groups, amide groups, cyano groups, carbamate groups, epoxy groups, and isocyanate groups.

[0032] Furthermore, "atomic transfer radical polymerization (ATRP)," used to form hyperbranched polymers, is a type of living radical polymerization that uses organic halides as initiators and metal complexes with transition metals as the central metals as catalysts to radically polymerize monomers. Atomic transfer radical polymerization allows for control of the molecular weight and molecular weight distribution of the resulting polymer.

[0033] Since compound (B) has a (meth)acrylate group and a halogenated functional group as reactive functional groups, a hyperbranched polymer can be synthesized by atom transfer radical polymerization of compound (A) and compound (B).

[0034] The hyperbranched polymer preferably contains 1 to 30 mol% of compound (A), more preferably 5 to 25 mol%. The compound (B) content is preferably 0.1 to 50 mol%, more preferably 2 to 15 mol%. When the content of compound (A) and compound (B) in the hyperbranched polymer is within this range, the lubricating oil composition obtained by adding the hyperbranched polymer has low viscosity and excellent friction reduction effects.

[0035] Furthermore, the molar ratio of compound (A) to compound (B) in the hyperbranched polymer is preferably, for example, 1:1 to 10:1, and more preferably 3:1 to 8:1. When the molar ratio of compound (A) to compound (B) is within this range, the lubricating oil composition obtained by adding the hyperbranched polymer has low viscosity and excellent friction reduction effect.

[0036] The hyperbranched polymer preferably has a number-average molecular weight (Mn) of 5,000 to 50,000, and more preferably 8,000 to 25,000. Furthermore, the hyperbranched polymer preferably has a weight-average molecular weight (Mw) of 5,000 to 100,000, and more preferably 10,000 to 50,000. When the number-average molecular weight (Mn) and weight-average molecular weight (Mw) are within this range, the lubricating oil composition obtained by adding the hyperbranched polymer has low viscosity and excellent friction-reducing effects.

[0037] The hyperbranched polymer preferably has a molecular weight distribution (Mw / Mn) of 1.0 to 3.8, and more preferably 1.2 to 3.0. When the molecular weight distribution (Mw / Mn) is within this range, the lubricating oil composition obtained by adding the hyperbranched polymer has low viscosity and excellent friction reduction effect.

[0038] The hyperbranched polymer preferably has a molar branching degree of 1 to 50 mol%, and more preferably 5 to 40 mol%. When the molar branching degree is within this range, the lubricating oil composition obtained by adding the hyperbranched polymer has low viscosity and excellent friction reduction effect.

[0039] <Method for producing hyperbranched polymers> The method for producing hyperbranched polymers of the present invention is as follows: (A) Alkyl (meth)acrylate, and (B) Compounds having a (meth)acrylate group and a halogenated functional group The process includes a polymerization step in which atoms are subjected to atom transfer radical polymerization.

[0040] According to the method for producing hyperbranched polymers of the present invention, the above-mentioned hyperbranched polymers can be easily obtained.

[0041] As for compounds (A) and (B), their descriptions are as described above, so we will omit further explanation.

[0042] Furthermore, the compounds described above can be used as initiators for atom transfer radical polymerization.

[0043] Atomic transfer radical polymerization can be carried out using known methods and conditions.

[0044] Specifically, the transition metal complex used as a catalyst for atom transfer radical polymerization is not particularly limited, but is preferably a metal complex with a group 7, 8, 9, 10, or 11 element of the periodic table as the central metal. More preferably, the catalyst is a complex of 0-valent copper, 1-valent or 2-valent copper, 2-valent ruthenium, 2-valent iron, or 2-valent nickel. Among these, the catalyst is particularly preferably a copper complex. Examples of copper compounds include copper chloride, copper bromide, copper iodide, copper cyanide, copper oxide, and copper perchlorate. When using a copper compound, 2,2'-bipyridyl or its derivatives, 1,10-phenanthroline or its derivatives, tetramethylethylenediamine, pentamethyldiethylenetriamine, hexamethyltris(2-aminoethyl)amine, and other polyamines can be added as ligands to enhance catalytic activity.

[0045] Furthermore, atom transfer radical polymerization can be carried out without a solvent, but it can also be carried out in various solvents. The type of solvent is not particularly limited, and examples include hydrocarbon solvents such as bendiene and toluene; ether solvents such as diethyl ether, tetrahydrofuran, diphenyl ether, anisole, and dimethoxybendiene; halogenated hydrocarbon solvents such as methylene chloride, chloroform, and chlorobendiene; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol, propanol, isopropanol, n-butyl alcohol, and tert-butyl alcohol; nitrile solvents such as acetonitrile, propionitrile, and benzonitrile; ester solvents such as ethyl acetate and butyl acetate; carbonate solvents such as ethylene carbonate and propylene carbonate; and amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide. These can be used individually or in combination of two or more.

[0046] Furthermore, atom transfer radical polymerization can be carried out in the range of 0 to 200°C, preferably in the range of room temperature to 150°C, and more preferably in the range of 50 to 120°C.

[0047] Figure 1 shows an example of a method for producing a hyperbranched polymer according to the present invention. This example shows a method for producing a hyperbranched polymer by atom transfer radical polymerization using lauryl methacrylate (LM) as compound (A) and 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl methacrylate (BIBEM) as compound (B).

[0048] <Additives for lubricating oils> The hyperbranched polymer described above can be used as an additive for lubricating oils. That is, the lubricating oil additive of the present invention consists of the hyperbranched polymer of the present invention described above.

[0049] <Lubricating oil composition> The lubricating oil composition of the present invention comprises a base oil and the lubricating oil additive of the present invention (hyperbranched polymer). Because the lubricating oil composition of the present invention contains the lubricating oil additive of the present invention (hyperbranched polymer), it has lower viscosity and superior friction reduction effect compared to conventional lubricants.

[0050] The amount of lubricating additive (hyperbranched polymer) added to the lubricating oil composition of the present invention can be appropriately adjusted considering the degree of branching of the hyperbranched polymer, viscosity and frictional resistance according to the application of the lubricating oil composition, etc. For example, the amount of lubricating additive (hyperbranched polymer) added to the lubricating oil composition of the present invention can be exemplified as being in the range of 1 to 20% by mass.

[0051] The viscosity of the lubricating oil composition of the present invention can be appropriately adjusted depending on the application, but for example, a range of 5 to 10,000 mPa·s can be used as a guideline.

[0052] Examples of base oils include mineral oil, synthetic oil, and mixed oils of mineral oil and synthetic oil.

[0053] Examples of mineral oils include atmospheric residues obtained by atmospheric distillation of crude oils such as paraffinic crude oil, intermediate crude oil, and naphthenic crude oil; distillates obtained by vacuum distillation of these atmospheric residues; and refined oils obtained by subjecting the distillates to one or more refining processes such as solvent delamination, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

[0054] Examples of synthetic oils include poly-α-olefins such as α-olefins and their homopolymers, or α-olefin copolymers (e.g., 8-14 carbon olefin copolymers such as ethylene-α-olefin copolymers); isoparaffins; polyalkylene glycols; ester oils such as polyol esters, dibasic acid esters, and phosphate esters; ether oils such as polyphenyl ethers; alkylbenzenes; alkylnaphthalenes; synthetic oils (GTL) obtained by isomerizing wax produced from natural gas by the Fischer-Tropsch process, etc. (GTL wax (Gas To Liquids Wax)); synthetic oils (CTL) obtained by isomerizing wax produced from coal by the Fischer-Tropsch process, etc. (CTL wax (Coal To Liquids Wax)); and synthetic oils (BTL) obtained by isomerizing wax produced from biomass by the Fischer-Tropsch process, etc. (BTL wax (Biomass To Liquids Wax)).

[0055] Furthermore, the lubricating oil composition may contain other additives. Examples of other additives include antioxidants, ashless dispersants, metallic detergents, viscosity index improvers, fluidity improvers, extreme pressure agents, rust inhibitors, friction modifiers, and wear inhibitors. These additives can be used individually or in combination.

[0056] The lubricating oil composition can be suitably used in engine oil (for gasoline, diesel, etc.), drivetrain oil (gear oil (manual transmission oil, differential oil, etc.), automatic transmission oil, hydraulic oil (power steering oil, shock absorber oil), etc.).

[0057] The lubricating oil composition of the present invention may optionally contain other optional components, such as other types of friction modifiers, viscosity index improvers, pour point depressants, oiliness agents, antioxidants, detergents, dispersants, antioxidants, defoamers, anti-emulsifiers, corrosion inhibitors, and the like.

[0058] The hyperbranched polymer of the present invention, its manufacturing method, lubricant additive, and lubricant composition are not limited to the embodiments described above. [Examples]

[0059] The present invention will be described below with reference to examples, but the hyperbranched polymer, lubricating oil additive, and lubricating oil composition of the present invention are not limited in any way to the following examples.

[0060] [Polymer synthesis] Hyperbranched polymers were synthesized using the ATRP method. Copper(II) bromide (CuBr2: 0.125 mmol), anisole (2.5 mL), lauryl methacrylate (LM), and BIBEM (LM + BIBEM: 10 mmol) were added to a 10 mL ampoule and stirred using a vortex mixer until a homogeneous solution was obtained. After filling the solution with nitrogen, ethyl 2-bromoisobutyrate (EBiB: 0.125 mmol) and N,N,N',N'-tetramethylethylenediamine (TMEDA: 2.5 mmol) were added using a microsyringe. After sealing the ampoule, it was stirred with a vortex mixer and heated at 70°C for a specified time. The reaction solution was diluted with tetrahydrofuran (THF), a small amount of activated alumina was added, and the mixture was stirred by magnetic stirring to remove Cu residue. The filtered solution was poured into methanol to precipitate the polymer. The recovered polymer was then dried at 40°C under reduced pressure for 6 hours and used for various measurements.

[0061] [Polymer structure] The structures of the various polymers obtained through synthesis are: 13 The samples were analyzed using 1C nuclear magnetic resonance (NMR) spectroscopy. The synthetic polymer samples were dissolved in chloroform-d (CDCl3: Thermo Fisher Scientific Co., Ltd.) and then loaded into 5 mm diameter NMR tubes. 13 ¹ 13 The 3C NMR spectrum was measured at a frequency of 600 MHz.

[0062] [Number-average molecular weight, weight-average molecular weight, and molecular weight distribution of polymers] The molecular weight of the sample oil was measured using a size exclusion chromatography system (HLC-8320GPC, manufactured by Tosoh Corporation). For sample preparation, THF was added to the sample to adjust the concentration to approximately 2 mg / mL, and then filtered through a 0.45 μm PTFE filter. The molecular weight of this filtrate was measured by size exclusion chromatography (SEC). The measurement conditions were as follows: eluent: tetrahydrofuran, column: TSKgel SuperHM-M (2 in series), detector: differential refractometer, measurement temperature: 40°C, flow rate: 0.6 mL / min, injection volume: 20 μL.

[0063] [Preparation of sample oil] Poly-alpha-olefin 4 (PAO4) was used as the base oil. In preparing the sample oil, various synthetic polymers were added to PAO4, stirred with a magnetic stirrer, and then used as the sample oil. The concentrations of the added synthetic polymers were adjusted to 1%, 5%, and 10%.

[0064] [Shear viscosity of sample oil] The shear viscosity of the sample oil was measured by rotational viscosity measurement using a dynamic viscoelasticity analyzer (MCR302, manufactured by AntonPaar Co., Ltd.). A 50 mm cone plate sensor (angle 1°) was used. The measurement conditions were a measurement temperature of 80°C and a shear rate of 10 s. -1 from 1000s -1 The measurement results showed Newtonian properties, so the shear rate was 10s. -1 The value was adopted.

[0065] [Friction evaluation of sample oil] The friction evaluation of the sample oil was measured using a ball-on-three-pin type tester attached to a dynamic viscoelasticity apparatus (MCR302, manufactured by Anton Paar Co., Ltd.). The test specimens were a combination of a ball and pins, and the material used was JIS SUJ2. The ball had a diameter of 12.7 mm and a surface roughness of Ra 0.1 mm. The pin had a cylindrical shape with a diameter of 6.0 mm and a thickness of 6.0 mm, and the surface roughness of the end face was Ra 0.1 mm as the measured value in the direction perpendicular to the sliding direction. For the evaluation of the slip velocity dependence of friction, the slip velocity was 0.000001 - 1 m / s, the temperature was 80°C, and the load was 1 N (P mean 0.4 Pa). For the evaluation of the time dependence of friction, the slip velocity was 0.1 m / s, the temperature was 80°C, the measurement time was 3600 s, and the load was 1 N (P mean 0.4 GPa).

[0066] According to the above-mentioned polymer synthesis method (ATRP method), synthetic polymers of Examples 1 - 12 were obtained under the conditions shown in Table 1. Also, synthetic polymers or sample oils of Comparative Examples 1 - 5 were prepared.

[0067]

Table 1

[0068] <NMR Analysis and GPC Measurement> [Example 1] The 13 C-NMR spectrum of the synthetic polymer of Example 1 (HB-Poly(LM-co-BIBEM)-1) is shown in Figure 2. By comparison with Comparative Example 1 (Liner-Poly(LM)), the peak shape around 25 ppm - 40 ppm became complex, suggesting differences in branching and side chain structures. Furthermore, peaks around 100 ppm and 70 ppm related to the structure derived from BIBEM were observed. Based on the results in Figure 2, the molar branching degree of Example 1 was calculated from the intensities of the peaks of methylene carbons adjacent to the oxygen in the side chain (LM: 67.4 ppm, BIBEM: 70.2 ppm), and the result was 6.1 mol%.

[0069] Furthermore, the GPC measurement results for Example 1 showed that the weight-average molecular weight (Mw) was 18,000 and the molecular weight distribution (Mw / Mn) was 1.47 (Table 1).

[0070] [Example 2] The synthetic polymer of Example 2 (HB-Poly(LM-co-BIBEM)-2) 13 The 1C-NMR spectrum is shown in Figure 2. Compared with Comparative Example 1, the peak shape around 25 ppm to 40 ppm was complex, suggesting differences in branching and side chain structure. Furthermore, peaks around 100 ppm and 70 ppm, related to the structure derived from BIBEM, were observed. Based on the results in Figure 2, the molar branching degree of Example 2 was calculated from the intensity of the methylene carbon peak adjacent to the oxygen in the side chain (LM: 67.4 ppm, BIBEM: 70.2 ppm) and was found to be 12.1 mol%.

[0071] Furthermore, GPC measurement results for Example 2 confirmed that the weight-average molecular weight (Mw) was 15,000 and the molecular weight distribution (Mw / Mn) was 1.47 (Table 2).

[0072] [Example 3] The synthetic polymer of Example 3 (HB-Poly(LM-co-BIBEM)-3) 13 The 1C-NMR spectrum is shown in Figure 2. Compared with Comparative Example 1, the peak shape around 25 ppm to 40 ppm was complex, suggesting differences in branching and side chain structure. Furthermore, peaks around 100 ppm and 70 ppm, which are related to the structure derived from BIBEM, were observed. Based on the results in Figure 2, the molar branching degree of Example 3 was calculated from the intensity of the methylene carbon peak adjacent to the oxygen in the side chain (LM: 67.4 ppm, BIBEM: 70.2 ppm) and was found to be 22.5 mol%.

[0073] Furthermore, GPC measurement results for Example 3 confirmed that the weight-average molecular weight (Mw) was 13,100 and the molecular weight distribution (Mw / Mn) was 1.49 (Table 2).

[0074] [Comparative Example 1] The synthetic polymer (Liner-Poly(LM)) of Comparative Example 1 13 The 1C-NMR spectrum results are shown in Figure 2. Peaks were observed around 35 ppm to 40 ppm and around 67 ppm.

[0075] Furthermore, GPC measurement results for Comparative Example 1 confirmed that the weight-average molecular weight (Mw) was 24,600 and the molecular weight distribution (Mw / Mn) was 1.19 (Table 2).

[0076] [Table 2]

[0077] <Shear viscosity measurement> Shear viscosity was measured using the sample oil from Example 4, and the viscosity was found to be 5.26 mPa·s (Table 3). Compared to Comparative Example 2 of the same concentration, the viscosity showed a tendency to decrease.

[0078] Shear viscosity was measured using the sample oil from Example 5, and the viscosity was found to be 5.15 mPa·s (Table 3). Compared to Comparative Example 2 of the same concentration, the viscosity showed a tendency to decrease.

[0079] Shear viscosity was measured using the sample oil from Example 6, and the viscosity was found to be 5.15 mPa·s (Table 3). Compared to Comparative Example 2 of the same concentration, the viscosity showed a tendency to decrease.

[0080] Shear viscosity was measured using the sample oil from Example 7, and the viscosity was found to be 6.33 mPa·s (Table 3). Compared to Comparative Example 3 of the same concentration, the viscosity showed a tendency to decrease.

[0081] Shear viscosity was measured using the sample oil from Example 8, and the viscosity was found to be 6.08 mPa·s. Compared to Comparative Example 3 of the same concentration, the viscosity showed a tendency to decrease.

[0082] Shear viscosity was measured using the sample oil from Example 9, and the viscosity was found to be 5.93 mPa·s (Table 3). Compared to Comparative Example 3 of the same concentration, the viscosity showed a tendency to decrease.

[0083] Using the sample oil from Example 10, the shear viscosity measurement results were as follows, with a viscosity of 7.83 mPa·s (Table 3). Compared to Comparative Example 4 of the same concentration, the viscosity showed a tendency to decrease.

[0084] Shear viscosity was measured using the sample oil from Example 11, and the viscosity was found to be 7.49 mPa·s (Table 3). Compared to Comparative Example 4 of the same concentration, the viscosity showed a tendency to decrease.

[0085] Shear viscosity was measured using the sample oil from Example 12, and the viscosity was found to be 7.25 mPa·s. Compared to Comparative Example 4 of the same concentration, the viscosity showed a tendency to decrease.

[0086] Shear viscosity was measured using the sample oil from Comparative Example 2, and the viscosity was found to be 5.32 mPa·s (Table 3).

[0087] Shear viscosity was measured using the sample oil from Comparative Example 3, and the viscosity was found to be 6.64 mPa·s (Table 3).

[0088] Shear viscosity was measured using the sample oil from Comparative Example 4, and the viscosity was found to be 8.77 mPa·s (Table 3).

[0089] Shear viscosity was measured using the sample oil of Comparative Example 5, and the viscosity was found to be 4.82 mPa·s (Table 3).

[0090] [Table 3]

[0091] <Friction evaluation> Figure 3 shows the change in the coefficient of friction with respect to sliding speed for the sample oils (Table 1) of Examples 4-6 and Comparative Examples 2 and 5.

[0092] As shown in Figure 3, Example 4 showed a tendency for the coefficient of friction to decrease compared to Comparative Example 5. Furthermore, compared to Comparative Example 2, which had an oil-soluble polymer added, Example 4 showed a high friction reduction effect in the low sliding speed range of 0.00001 to 0.0001 m / s.

[0093] Examples 5 and 6 showed a tendency for the coefficient of friction to decrease compared to Comparative Examples 2 and 5. In particular, they showed a high friction reduction effect in the low sliding speed range of 0.00001 to 0.0001 m / s.

[0094] Figure 4 shows the time variation of friction at a sliding velocity of 0.1 m / s for the sample oils (Table 1) of Examples 4-6 and Comparative Examples 2 and 5.

[0095] As shown in Figure 4, Example 4 exhibited similar friction behavior to Comparative Example 2 up to 80 seconds and to Comparative Example 5 up to 200 seconds, but thereafter the coefficient of friction tended to decrease.

[0096] Compared to Comparative Examples 2 and 5, Example 5 showed a lower coefficient of friction from 400 seconds of measurement onwards, and continued to demonstrate a friction reduction effect thereafter.

[0097] Compared to Comparative Examples 2 and 5, Example 6 showed a lower coefficient of friction from 100 seconds of measurement onwards, and continued to exhibit a high friction reduction effect thereafter.

Claims

1. (A) alkyl (meth)acrylate, and (B) Compounds having a (meth)acrylate group and a halogenated functional group It is an atom-transfer radical polymer, Hyperbranched polymer.

2. The alkyl group of compound (A) has 6 to 18 carbon atoms. The hyperbranched polymer according to claim 1.

3. The halogenated functional group is a 2-halo-2-methylpropanoyl group. The hyperbranched polymer according to claim 1.

4. The compound (B) is 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl acrylate or 2-[(2-bromo-2-methylpropanoyl)oxy]ethyl methacrylate. The hyperbranched polymer according to claim 1.

5. The content of the aforementioned compound (A) is 1 to 30 mol%, The hyperbranched polymer according to claim 1.

6. The content of the aforementioned compound (B) is 0.1 to 50 mol%, The hyperbranched polymer according to claim 1.

7. The number-average molecular weight (Mn) is between 5,000 and 50,000. The hyperbranched polymer according to claim 1.

8. The molar branching degree is 1 to 50 mol%. The hyperbranched polymer according to claim 1.

9. The molecular weight distribution (Mw / Mn) is between 1.0 and 3.

8. The hyperbranched polymer according to claim 1.

10. (A) alkyl (meth)acrylate, and (B) Compounds having a (meth)acrylate group and a halogenated functional group A polymerization step is included in which the atom is subjected to atom transfer radical polymerization. A method for producing hyperbranched polymers.

11. A hyperbranched polymer according to claim 1, Lubricant additive.

12. A base oil comprising the lubricating oil additive of claim 11, Lubricating oil composition.

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