Viscosity index improver and its lubricant composition

Abstract

To provide a poly alkyl(meth)acrylate polymer comprising polybutadiene-based monomer units and a process for preparing the same, and to provide the use of the polymer as a viscosity index improver in lubricant formulation and lubricant compositions comprising the polymer.SOLUTION: There is provided a poly alkyl(meth)acrylate polymer, which is obtainable by polymerizing a monomer composition comprising: a) 15 to 35 mass% of one or more polybutadiene-based macromonomer having a number-average molecular weight of 500 to 10,000 g / mol, based on the total mass of the monomer composition; and b) 40 to 85 mass% of n-propyl(meth)acrylate, iso-propyl(meth)acrylate or a mixture thereof, based on the total mass of the monomer composition, and the poly alkyl(meth)acrylate polymer has a weight-average molecular weight (Mw) from 50,000 to 250,000 g / mol.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyalkyl (meth) acrylate polymer containing polybutadiene-based monomer units and a method for producing the same. The present invention also relates to the use of the polymer as a viscosity index improver in a lubricant formulation and to a lubricant composition containing the polymer.

Background Art

[0002] Due to strict automotive regulations in various countries regarding CO2 emissions and fossil fuel consumption, the automotive industry is forced to develop systems for achieving better fuel efficiency. One of them is the modification of hardware and the use of lightweight materials. There is also a method of using a low-viscosity grade lubricant in a transmission or an engine. In this case, since the viscosity needs to be high enough to protect the metal parts of the transmission or the engine, there are some limitations. Therefore, it is important to adjust the viscosity to an optimal value and keep it as constant as possible over the entire temperature range in the application.

[0003] A lubricant is a composition that reduces friction between surfaces. A lubricant can enable free movement between two surfaces and reduce mechanical wear of the surfaces, and in addition, can suppress surface corrosion and / or damage to the surface due to heat or oxidation. Examples of lubricant compositions include, but are not limited to, engine oil, transmission fluid, gear oil, industrial lubricating oil, grease, and metalworking oil. A lubricant usually contains a base fluid and various amounts of additives. Depending on the purpose of use of the lubricant, a wide variety of additives can be formulated into the base fluid. Examples of lubricant additives include, but are not limited to, viscosity index improvers, thickeners, antioxidants, corrosion inhibitors, dispersants, extreme pressure additives, defoamers, and metal deactivators.

[0004] Polymeric additives are used to thicken base oils and reduce viscosity changes due to temperature variations. The term viscosity index (VI) is used to represent this temperature-induced viscosity change. Viscosity index improvers (VIIs) are typically used to improve the temperature dependence of lubricants as indicated by the viscosity index (VI). VI is calculated from the kinematic viscosity (KV 40 ) at 40 °C and the kinematic viscosity (KV 100 ) at 100 °C. The higher the VI, the lower the temperature dependence of the lubricant's viscosity, meaning less change in viscosity with temperature. For this reason, viscosity index improvers (VIIs) may be added to lubricant formulations to increase the VI of the lubricant formulation. A drawback of adding polymeric additives to lubricant formulations is that these additives are subject to shear stress and are mechanically degraded over time.

[0005] Thus, regardless of the viscosity index, the shear resistance of the lubricant is an important factor. That is, on the one hand, the lifespan of the lubricant is extended, and more resistant lubricants are demanded. On the other hand, the viscosity of the lubricating oil is reduced, minimizing the possibility of viscosity reduction due to shear loss without causing problems in metal parts.

[0006] Polyalkyl (meth)acrylate (PAMA) polymers, especially those containing polybutadiene-based monomers, are known to act as good viscosity index improvers in lubricants.

[0007] European Patent Application Publication No. 3498808 describes a polyalkyl (meth)acrylate containing a combination of polybutadiene-based monomers having different molecular weights and the use of such polymers as lubricant additives to improve the shear resistance of lubricants.

[0008] WO 2007 / 003238, WO 2009 / 007147, and WO 2010 / 142789 disclose the use of a polymer containing a macromonomer derived from polybutadiene as a viscosity index improver, where the macromonomer has a molecular weight of 500 to 50,000 g / mol.

[0009] WO 2018 / 174188 discloses a polymer containing a macromonomer derived from polybutadiene as a viscosity index improver.

[0010] WO 2015 / 129732, Japanese Patent No. 6234974, JP 2017-031400 A, and JP 2017-171899 A disclose polymers containing macromonomers derived from polybutadiene having different molecular weights as viscosity index improvers.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Summary of the Invention

Problems to be Solved by the Invention

[0012] There is still a need to develop a novel viscosity index improver that not only has a high viscosity index but also has excellent shear resistance in lubricant formulations. Accordingly, an object of the present invention is to provide a viscosity index improver for use in a lubricating oil composition in which the viscosity index is improved and good shear resistance is maintained as compared with viscosity index improvers known from the prior art.

Means for Solving the Problems

[0013] Surprisingly, it has been found that the polyalkyl (meth) acrylate polymer as defined in claim 1 solves the above technical problem by providing a combination of good shear stability and a high viscosity index in a lubricant formulation. By using a combination of a polybutadiene-based macromonomer and a large amount of linear or branched propyl (meth) acrylate in the monomer composition, the resulting polyalkyl (meth) acrylate polymer has a high viscosity index and good shear stability when used in a lubricant formulation.

[0014] Accordingly, the present invention relates, in a first aspect, to a polyalkyl (meth) acrylate polymer as defined in claim 1.

[0015] The present invention relates, in a second aspect, to a method for producing the polyalkyl (meth) acrylate polymer.

[0016] The present invention relates, in a third aspect, to the use of the polyalkyl (meth) acrylate polymer according to the present invention as an additive in a lubricant composition for improving the viscosity index of the lubricant composition while maintaining good shear resistance.

[0017] In a fourth aspect, the present invention relates to a composition containing one or more base oils and a polyalkyl (meth) acrylate as defined in the present invention.

Mode for Carrying Out the Invention

[0018] The polymer of the present invention In a first aspect, the present invention relates to a polyalkyl (meth) acrylate polymer, wherein the polyalkyl (meth) acrylate polymer a) one or more polybutadiene-based macromonomers having a number average molecular weight of 500 to 10,000 g / mol, based on the total mass of the monomer composition, 15 to 35% by mass, and b) n-propyl (meth) acrylate, isopropyl (meth) acrylate, or a mixture thereof, based on the total mass of the monomer composition, 40 to 85% by mass, and is obtained by polymerizing a monomer composition containing the same, the polyalkyl (meth) acrylate polymer has a weight average molecular weight (M w ) of 50,000 to 250,000 g / mol.

[0019] The amount by mass of the monomer is, unless otherwise stated, based on the total amount of the monomer, that is, the total mass of the monomer composition.

[0020] The amounts of monomer a) and monomer b) in the monomer composition together constitute at least 70% by mass based on the total mass of the monomer composition. That is, the amounts of monomer a) and monomer b) are each selected so that the total is at least 70% by mass based on the total amount of the monomer composition, and the remaining amount is a monomer other than monomer a) and b), corresponding to the monomer contained in the monomer composition. Preferably, the total amount of monomer a) and monomer b) in the monomer composition is 70% to 100% by mass based on the total mass of the monomer composition.

[0021] The polybutadiene-based macromonomer a) of the present invention is an ester of (meth)acrylic acid, and the ester is a reaction product (by transesterification) of one kind of ester of (meth)acrylic acid and one kind of hydroxylated hydrogenated polybutadiene, or any one of reaction products (by direct esterification) of one kind of (meth)acrylic acid and one kind of hydroxylated hydrogenated polybutadiene.

[0022] The polymer in the context of the present invention includes a first polymer, also called a backbone or main chain, and a number of further polymers called side chains and covalently bonded to the backbone. In this case, the backbone of the polymer is formed by the linked unsaturated groups of the (meth)acrylate. The alkyl group of the (meth)acrylate and the hydrogenated polybutadiene chain form the side chains of the polymer. A reaction product of one kind of ester of (meth)acrylic acid and one kind of hydroxylated hydrogenated polybutadiene, or a reaction product of one kind of (meth)acrylic acid and one kind of hydroxylated hydrogenated polybutadiene corresponds to monomer a), and in the present invention, it is also called a macromonomer or a polybutadiene-based macromonomer.

[0023] The term "(meth)acrylic acid" refers to acrylic acid, methacrylic acid, and a mixture of acrylic acid and methacrylic acid, and methacrylic acid is preferred. The term "(meth)acrylate" refers to an ester of acrylic acid, an ester of methacrylic acid, or a mixture of esters of acrylic acid and methacrylic acid, and an ester of methacrylic acid is preferred.

[0024] The polymer according to the present invention has a weight average molecular weight (M of 50,000 to 250,000 g / mol, preferably 70,000 to 200,000 g / mol, more preferably 100,000 to 170,000 g / mol, still more preferably 120,000 to 160,000 g / mol. w) have. Polymers having these weight average molecular weights are particularly suitable for use in transmission fluids such as automatic transmission fluids, manual transmission fluids, and belt continuously variable transmission fluids.

[0025] Preferably, the polydispersity index (PDI) of the polymer according to the present invention is in the range of 2.5 to 5.0, more preferably in the range of 3.0 to 4.5, and even more preferably in the range of 3.2 to 4.2. The polydispersity index is the ratio of the weight average molecular weight to the number average molecular weight (M w / M n ) and is defined as.

[0026] In the present invention, the weight average molecular weight (M w ) of the polymer is measured by gel permeation chromatography (GPC) using a polymethyl methacrylate calibration standard under the following measurement conditions: Eluent: Tetrahydrofuran (THF) Operating temperature: 40 ° C Column: The column set is composed of 4 columns: PSS-SDV 100 Å 10 μm 8.0 × 50 mm, 2 PSS-SDV Linear XL 10 μm 8.0 × 300 mm, PSS-SDV 100 Å 10 μm 8.0 × 300 mm, and the average particle diameter of all columns is 10 μm. Flow rate: 1 mL / min Injection volume: 100 μL Apparatus: Shodex GPC101 consisting of an autosampler, a pump, and a column oven Detector: Refractive index detector manufactured by Shodex.

[0027] The polymer according to the present invention can be characterized based on its molar branching degree (`` f 分岐 ''). The molar branching degree refers to the percentage in mol% of the macromonomer (monomer a)) used, based on the total molar amount of all monomers in the monomer composition. The molar amount of the macromonomer used is the number average molecular weight M of the macromonomer nIt is calculated based on the following. The calculation of the molar branching degree is described in detail in WO 2007 / 003238, particularly on pages 13 and 14, and the specification is hereby expressly incorporated by reference.

[0028] Preferably, the polymer has a molar branching degree f of 0.1 to 5 mol%, more preferably 1.5 to 4 mol%, and most preferably 1.5 to 2.5 mol%. 分岐 having.

[0029] Monomer a) According to the present invention, the monomer composition defined above contains, as monomer a), a polybutadiene-based macromonomer having a number average molecular weight (M n ) of 500 to 10,000 g / mol in an amount of 15 to 35% by mass based on the total mass of the monomer composition. Preferably, the polybutadiene-based macromonomer a) has a number average molecular weight (M n ) of 500 to 10,000 g / mol, more preferably 1,000 to 6,000 g / mol, still more preferably 1,500 to 2,500 g / mol, and most preferably 1,800 to 2,200 g / mol.

[0030] The hydroxylated hydrogenated polybutadiene for use according to the present invention has a number average molecular weight M of 500 to 10,000 g / mol, more preferably 1,000 to 6,000 g / mol, still more preferably 1,500 to 2,500 g / mol, and even more preferably 1,800 to 2,200 g / mol. n having. Since the hydroxylated hydrogenated polybutadiene has a large molecular weight, it may also be referred to as a macroalcohol in the context of the present invention. The corresponding ester of (meth)acrylic acid may also be referred to as a macromonomer in the context of the present invention (monomer a)).

[0031] The number average molecular weight M of the macromonomer nIt is determined by gel permeation chromatography (GPC) using a polybutadiene calibration standard (PSS Standards Service GmbH, Mainz, Germany) in accordance with DIN 55672-1 under the following measurement conditions: Eluent: Tetrahydrofuran (THF) containing 0.02 M 2-diethylaminoethylamine Operating temperature: 35 °C Column: The column set consists of four columns: SDV 106 Å, SDV 104 Å, and SDV 103 Å (PSS Standards Service GmbH, Mainz, Germany). All columns have a size of 300 × 8 mm and an average particle diameter of 10 μm Flow rate: 1 mL / min Injection volume: 100 μL Apparatus: Agilent 1100 series consisting of an autosampler, a pump, and a column oven Detector: Refractive index detector from the Agilent 1260 series.

[0032] The monomer composition preferably contains 15 to 30% by mass, more preferably 20 to 30% by mass, of a polybutadiene-based macromonomer a) having a number average molecular weight (M n ) of 500 to 10,000 g / mol, preferably 1,000 to 6,000 g / mol, more preferably 1,500 to 2,500 g / mol, and even more preferably 1,800 to 2,200 g / mol, based on the total mass of the monomer composition.

[0033] The hydroxylated hydrogenated polybutadiene preferably has a hydrogenation degree of at least 99%. An alternative measure of the hydrogenation degree that can be determined for the polymers of the present invention is the iodine value. The iodine value refers to the number of grams of iodine that can be added to 100 g of the polymer. The polymers of the present invention preferably have an iodine value of 5 g or less of iodine per 100 g of the polymer. The iodine value is determined in accordance with DIN 53241-1:1995-05 by the Wijs method.

[0034] Preferred hydroxylated hydrogenated polybutadiene can be obtained according to the specification of British Patent Application Publication No. 2270317.

[0035] As used herein, the term "hydroxylated (hydrogenated) polybutadiene" refers to hydrogenated polybutadiene containing one or more hydroxy groups. The hydroxylated hydrogenated polybutadiene may further contain additional structural units, such as polyether groups derived from the addition of alkylene oxides to polybutadiene, or maleic anhydride groups derived from the addition of maleic anhydride to polybutadiene. These additional structural units may be introduced into the polybutadiene when the polybutadiene is functionalized with hydroxy groups.

[0036] It is preferably monohydroxylated hydrogenated polybutadiene. More preferably, the hydroxylated hydrogenated polybutadiene is hydrogenated polybutadiene having hydroxyethyl or hydroxypropyl as end groups. Particularly preferably, it is polybutadiene having hydroxypropyl as an end group.

[0037] These monohydroxylated hydrogenated polybutadienes can be produced by first converting butadiene monomers into polybutadiene by anionic polymerization. Subsequently, hydroxy-functionalized polybutadiene can be produced by reacting the polybutadiene monomer with an alkylene oxide, such as ethylene oxide or propylene oxide. The polybutadiene may be reacted with more than one alkylene oxide unit to yield a polyether-polybutadiene block copolymer having terminal hydroxy groups. The hydroxylated polybutadiene can be hydrogenated in the presence of a suitable transition metal catalyst.

[0038] These monohydroxylated hydrogenated polybutadienes can also be selected from products obtained by hydroboration of (co)polymers having terminal double bonds (as described, for example, in U.S. Patent No. 4,316,973), amino alcohols, maleic anhydride-ene-amino alcohol adducts obtained by an ene reaction of (co)polymers having terminal double bonds and maleic anhydride, and products obtained by hydroformylation of (co)polymers having terminal double bonds followed by hydrogenation (as described, for example, in JP-A-63-175096).

[0039] The macromonomer a) for use in the present invention can be produced by transesterification of an alkyl (meth)acrylate. The ester of the present invention is formed by the reaction of the alkyl (meth)acrylate and the hydroxylated hydrogenated polybutadiene. It is preferable to use methyl (meth)acrylate or ethyl (meth)acrylate as a starting material.

[0040] This transesterification is widely known. For example, for this purpose, a heterogeneous catalyst system such as a lithium hydroxide / calcium oxide mixture (LiOH / CaO), pure lithium hydroxide (LiOH), lithium methoxide (LiOMe) or sodium methoxide (NaOMe), or a homogeneous catalyst system such as isopropyl titanate (Ti(OiPr)4) or dioctyltin oxide (Sn(OCt)2O) can be used. The reaction is an equilibrium reaction. Therefore, the low molecular weight alcohol released is generally removed, for example, by distillation.

[0041] Furthermore, the macromonomer can be obtained directly by an esterification method, for example, from (meth)acrylic acid or an anhydride of (meth)acrylic acid, preferably under acid catalysis by p-toluenesulfonic acid or methanesulfonic acid, or from free methacrylic acid by the DCC method (dicyclohexylcarbodiimide).

[0042] Furthermore, the hydroxylated hydrogenated polybutadiene according to the present invention can be converted into an ester by reaction with an acid chloride, for example, (meth)acryloyl chloride.

[0043] Preferably, in the production of the ester of the present invention detailed above, a polymerization inhibitor such as 4-hydroxy-2,2,6,6-tetramethylpiperidinooxyl radical and / or hydroquinone monomethyl ether is used.

[0044] Monomer b) The monomer composition contains, as monomer b), n-propyl (meth)acrylate, iso-propyl (meth)acrylate or a mixture thereof in an amount of 40 to 85% by mass, preferably 45 to 85% by mass, more preferably 45 to 80% by mass, based on the total mass of the monomer composition.

[0045] In another preferred embodiment of the present invention, the monomer composition may further contain additional comonomers. These comonomers are described below as monomers c), d), e) and f).

[0046] Monomer c) Preferably, in addition to monomers a) and b), the monomer composition further contains monomer c). Monomer c) is selected from the group consisting of methyl (meth)acrylate, butyl (meth)acrylate, or a mixture thereof.

[0047] In another particularly preferred embodiment of the present invention, the monomer composition contains one or more monomers c) selected from the group consisting of methyl (meth)acrylate, butyl (meth)acrylate, or a mixture thereof in an amount of 0 to 30% by mass, more preferably 0.1 to 30% by mass, even more preferably 1 to 25% by mass, based on the total mass of the monomer composition.

[0048] Preferably, the amounts of monomers a), b) and c) together are 95 to 100% by mass, preferably 100% by mass in total, based on the total mass of the monomer composition.

[0049] Monomer d) Preferably, the monomer composition may further contain one or more monomers d) selected from the group consisting of styrene; substituted styrenes having an alkyl substituent in the side chain, such as α-methylstyrene and α-ethylstyrene; substituted styrenes having an alkyl substituent in the ring, such as vinyltoluene and para-methylstyrene; halogenated styrenes, such as monochlorostyrene, dichlorostyrene, tribromostyrene and tetrabromostyrene; and nitrostyrene, which are styrene monomers having 8 to 17 carbon atoms. A particularly preferred monomer d) is styrene.

[0050] In another particularly preferred embodiment of the present invention, the monomer composition contains one or more monomers d) in an amount of 0 to 25% by mass, more preferably 0.1 to 25% by mass, still more preferably 0.1% to 10% by mass, and most preferably 0.1 to 5% by mass, based on the total mass of the monomer composition.

[0051] Preferably, the amounts of monomers a), b), c) and d) together are 95 to 100% by mass, based on the total mass of the monomer composition.

[0052] Monomer e) In another particularly preferred embodiment of the present invention, the monomer composition may further contain one or more monomers e) which are C 7~30 alkyl (meth) acrylates, and any monomers c) and d).

[0053] Regarding the monomer e), "C 7~30The term "alkyl (meth)acrylate" refers to an ester of (meth)acrylic acid and a linear or branched alcohol having from 7 to 30 carbon atoms. This term encompasses the individual (meth)acrylic acid esters with alcohols of a specific length, as well as mixtures of (meth)acrylic acid esters with alcohols of different lengths.

[0054] Suitable C 7~30Alkyl (meth)acrylate includes, for example, 2-butyloctyl (meth)acrylate, 2-hexyloctyl (meth)acrylate, decyl (meth)acrylate, 2-butyldecyl (meth)acrylate, 2-hexyldecyl (meth)acrylate, 2-octyldecyl (meth)acrylate, undecyl (meth)acrylate, 5-methylundecyl (meth)acrylate, dodecyl (meth)acrylate, 2-methyldodecyl (meth)acrylate, 2-hexyldodecyl (meth)acrylate, 2-octyldodecyl (meth)acrylate, tridecyl (meth)acrylate, 5-methyltridecyl (meth)acrylate, tetradecyl (meth)acrylate, 2-decyltetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, 2-methylhexadecyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, heptadecyl (meth)acrylate, 5-isopropylheptadecyl (meth)acrylate, 4-tert-butyloctadecyl (meth)acrylate, 5-ethyloctadecyl (meth)acrylate, 3-isopropyloctadecyl (meth)acrylate, octadecyl (meth)acrylate, 2-decyloctadecyl (meth)acrylate, 2-tetradecyloctadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, cetyleicosyl (meth)acrylate, stearyleicosyl (meth)acrylate, docosyl (meth)acrylate, eicosyltetratriacontyl (meth)acrylate, 2-decyl-tetradecyl (meth)acrylate, 2-decyloctadecyl (meth)acrylate, 2-dodecyl-1-hexadecyl (meth)acrylate, 1,2-octyl-1-dodecyl (meth)acrylate, 2-tetradecyloctadecyl (meth)acrylate, 1,2-tetradecyl-octadecyl (meth)acrylate, and 2-hexadecyl-eicosyl (meth)acrylate, n-tetracosyl (meth)acrylate, n-triacontyl (meth)acrylate, and / or n-hexatriacontyl (meth)acrylate.

[0055] In another preferred embodiment of the present invention, the monomer composition contains, based on the total mass of the monomer composition, 0 to 15% by mass, preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, even more preferably 1 to 3% by mass of one or more monomers e) selected from linear or branched C7-C 30 alkyl (meth)acrylates, preferably linear or branched C7-C C22 alkyl (meth)acrylates, or mixtures thereof. Particularly preferred monomers e) are selected from the group consisting of linear or branched C 12 -C 14 alkyl (meth)acrylates, linear or branched C 16 -C 18 alkyl (meth)acrylates, or mixtures thereof.

[0056] The term "C 12~14 alkyl (meth)acrylate" refers to an ester of (meth)acrylic acid and a linear or branched alcohol having 12 to 14 carbon atoms. This term encompasses the individual (meth)acrylic acid esters with alcohols of a specific length, as well as mixtures of (meth)acrylic acid esters with alcohols of different lengths. Suitable C 12~14 alkyl (meth)acrylates include, for example, dodecyl methacrylate, 2-methyldodecyl methacrylate, tridecyl methacrylate, 5-methyltridecyl methacrylate and / or tetradecyl methacrylate.

[0057] Similarly, C 16~18The alkyl (meth)acrylate may be independently selected from the group consisting of, for example, hexadecyl (meth)acrylate, 2-methylhexadecyl (meth)acrylate, heptadecyl (meth)acrylate, 5-isopropylheptadecyl (meth)acrylate, 4-tert-butyloctadecyl (meth)acrylate, 5-ethyloctadecyl (meth)acrylate, 3-isopropyloctadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, cetyleicosyl (meth)acrylate, stearyleicosyl (meth)acrylate, docosyl (meth)acrylate, behenyl (meth)acrylate, eicosyltetratriacontyl (meth)acrylate, cycloalkyl (meth)acrylate, 2,4,5-tri-t-butyl-3-vinylcyclohexyl (meth)acrylate, and 2,3,4,5-tetra-t-butylcyclohexyl (meth)acrylate. Particularly preferred C 16~18 The alkyl (meth)acrylate is stearyleicosyl (meth)acrylate.

[0058] Preferably, the amounts of monomers a), b), c), d) and e) in total are 95 to 100% by mass based on the total mass of the monomer composition.

[0059] Monomer f) In another preferred embodiment of the present invention, the monomer composition further contains one or more monomers f) in addition to monomers a) to b), and optionally c), d) and e).

[0060] Preferably, the monomer composition comprises one or more monomers f) selected from the group consisting of vinyl esters having 1 to 11 carbon atoms in the acyl group, vinyl ethers having 1 to 10 carbon atoms in the alcohol group, dispersible oxygen- and / or nitrogen-functionalized monomers, heterocyclic (meth)acrylates, heterocyclic vinyl compounds, monomers containing covalently bonded phosphorus atoms, monomers containing epoxy groups, and monomers containing halogens, more preferably one or more monomers f) selected from the group consisting of (meth)acrylates of ether alcohols, aminoalkyl (meth)acrylates, aminoalkyl (meth)acrylamides, vinyl monomers having an aromatic group, or mixtures thereof, in an amount of 0 to 10% by mass, more preferably 0.1 to 10% by mass, still more preferably 0.1 to 5% by mass, and most preferably 0.1 to 3% by mass.

[0061] Suitable vinyl esters having 1 to 11 carbon atoms in the acyl group are selected from the group consisting of vinyl formate, vinyl acetate, vinyl propionate, and vinyl butyrate, preferably vinyl esters containing 2 to 9, more preferably 2 to 5 carbon atoms in the acyl group, and the acyl group may be linear or branched.

[0062] Suitable vinyl ethers having 1 to 10 carbon atoms in the alcohol group are selected from the group consisting of vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, and vinyl butyl ether, preferably vinyl ethers containing 1 to 8, more preferably 1 to 4 carbon atoms in the alcohol group, and the alcohol group may be linear or branched.

[0063] Suitable monomers derived from dispersive oxygen-functionalized and / or nitrogen-functionalized monomers are aminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-diethylaminopentyl (meth)acrylate, N,N-dibutylaminohexadecyl (meth)acrylate; aminoalkyl (meth)acrylamides such as N,N-dimethylaminopropyl (meth)acrylamide; hydroxyalkyl (meth)acrylates such as 3-hydroxypropyl (meth)acrylate, 3,4-dihydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,5-dimethyl-1,6-hexanediol (meth)acrylate, 1,10-decanediol (meth)acrylate; p-hydroxystyrene, vinyl alcohol, alkenols (3 to 12 carbon atoms (methyl)allyl alcohol), ethers or meth(acrylates) of polyhydric (3 to 8 valent) alcohols (glycerol, pentaerythritol, sorbitol, sorbitan, diglyceride, saccharides); C 1~8 -alkyloxy-C 2~4- Alkyl (meth)acrylates, such as methoxypropyl (meth)acrylate, methoxybutyl (meth)acrylate, methoxyheptyl (meth)acrylate, methoxyhexyl (meth)acrylate, methoxypentyl (meth)acrylate, methoxyoctyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate, ethoxybutyl (meth)acrylate, ethoxyheptyl (meth)acrylate, ethoxyhexyl (meth)acrylate, ethoxypentyl (meth)acrylate, ethoxyoctyl (meth)acrylate, propoxymethyl (meth)acrylate, propoxyethyl (meth)acrylate, propoxypropyl (meth)acrylate, propoxybutyl (meth)acrylate, propoxyheptyl (meth)acrylate, propoxyhexyl (meth)acrylate, propoxypentyl (meth)acrylate, propoxyoctyl (meth)acrylate, butoxymethyl (meth)acrylate, butoxyethyl (meth)acrylate, butoxypropyl (meth)acrylate, butoxybutyl (meth)acrylate, butoxyheptyl (meth)acrylate, butoxyhexyl (meth)acrylate, butoxypentyl (meth)acrylate, and butoxyoctyl (meth)acrylate, selected from the group consisting thereof, with ethoxyethyl (meth)acrylate and butoxyethyl (meth)acrylate being preferred.

[0064] Suitable heterocyclic (meth)acrylates are selected from the group consisting of 2-(1-imidazolyl)ethyl (meth)acrylate, 2-(4-morpholinyl)ethyl (meth)acrylate, 1-(2-methacryloyloxyethyl)-2-pyrrolidone, N-methacryloylmorpholine, N-methacryloyl-2-pyrrolidinone, N-(2-methacryloyloxyethyl)-2-pyrrolidinone, N-(3-methacryloyloxypropyl)-2-pyrrolidinone.

[0065] Suitable complex cyclic vinyl compounds are selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine, 2,3-dimethyl-5-vinylpyridine, vinylpyrimidine, vinylpiperidine, 9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole, 1-vinylimidazole, 2-methyl-1-vinylimidazole, N-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinylpyrrolidine, N-vinylcaprolactam, N-vinylbutyrolactam, vinyloxolane, vinylfuran, vinyloxazole, and hydrogenated vinyloxazole.

[0066] Monomers containing a covalently bonded phosphorus atom are selected from the group consisting of 2-(dimethylphosphato)propyl (meth)acrylate, 2-(ethylenephosphito)propyl (meth)acrylate, dimethylphosphinomethyl (meth)acrylate, dimethylphosphonoethyl (meth)acrylate, diethyl (meth)acryloylphosphonate, dipropyl (meth)acryloylphosphate, 2(dibutylphosphono)ethyl (meth)acrylate, diethylphosphatoethyl (meth)acrylate, 2-(dimethylphosphato)-3-hydroxypropyl (meth)acrylate, 2-(ethylenephosphito)-3-hydroxypropyl (meth)acrylate, 3-(meth)acryloyloxy-2-hydroxypropyldiethylphosphonate, 3-(meth)acryloyloxy-2-hydroxypropyldipropylphosphonate, 3-(dimethylphosphato)-2-hydroxypropyl (meth)acrylate, 3-(ethylenephosphito)-2-hydroxypropyl (meth)acrylate, 2-(meth)acryloyloxy-3-hydroxypropyldiethylphosphonate, 2-(meth)acryloyloxy-3-hydroxypropyldipropylphosphonate and 2-(dibutylphosphono)-3-hydroxypropyl (meth)acrylate.

[0067] Suitable monomers f) having an epoxy group are, for example, glycidyl (meth)acrylate and glycidyl (meth)allyl ether.

[0068] Suitable monomers f) having a halogen are, for example, vinyl chloride, vinyl bromide, vinylidene chloride, (meth)allyl chloride, and halogenated styrene (dichlorostyrene), etc.

[0069] Particularly preferred monomers f) are (meth)acrylates of ether alcohols, aminoalkyl (meth)acrylates, aminoalkyl (meth)acrylamides or mixtures thereof, more preferably N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide and N-vinylpyrrolidone.

[0070] In another preferred embodiment of the present invention, the amounts of monomers a), b), c), d), e) and f) together are 95 to 100% by mass based on the total mass of the monomer composition.

[0071] Production method The present invention also relates to a method for producing the polymer, which method comprises the following steps: (x) A step of preparing the above monomer composition, (y) A step of initiating radical polymerization in the monomer composition.

[0072] Standard free radical polymerization is described in detail, inter alia, in Ullmann´s Encyclopedia of Industrial Chemistry, 6th Edition. Generally, for this purpose, a polymerization initiator and optionally a chain transfer agent are used.

[0073] ATRP itself is known. Although this is assumed to be "living" free radical polymerization, it is not intended to be limited by explaining this mechanism. In these methods, the transition metal compound is reacted with a compound having a movable atomic group. This involves the movable atomic group moving to the transition metal compound, and as a result, the metal is oxidized. This reaction forms free radicals, which add to the ethylene group. However, since the movement of the atomic group to the transition metal compound is reversible, the atomic group moves back to the growing polymer chain, resulting in the formation of a controlled polymerization system. Accordingly, it is possible to control the formation, molecular weight, and molecular weight distribution of the polymer.

[0074] This reaction mode is described, for example, in J.-S. Wang et al., J. Am. Chem. Soc, 1995, vol. 117, pp. 5614 - 5615, Matyjaszewski, Macromolecules, 1995, vol. 28, pp. 7901 - 7910. Further, the patent application specifications of International Publication No. 96 / 30421, International Publication No. 97 / 47661, International Publication No. 97 / 18247, International Publication No. 98 / 40415, and International Publication No. 99 / 10387 disclose modified methods of ATRP described above. Further, the polymers of the present invention can also be obtained via the RAFT method. This method is described in detail, for example, in International Publication No. 98 / 01478 and International Publication No. 2004 / 083169.

[0075] The polymerization can be carried out under standard pressure, reduced pressure, or elevated pressure. The polymerization temperature is not critical either. However, the polymerization temperature generally ranges from -20 to 200 °C, preferably from 50 to 150 °C, and more preferably from 80 to 130 °C.

[0076] Preferably, the monomer composition provided in step (x) is diluted by adding oil to provide a reaction mixture. The amount of the monomer composition, i.e., the total amount of monomers, relative to the total mass of this reaction mixture is preferably 20 to 90% by mass, more preferably 40 to 80% by mass, and most preferably 50 to 70% by mass.

[0077] Preferably, the oil used to dilute the monomer composition is an oil of API Group I, II, III, IV or V, or a mixture thereof. Preferably, Group III oil or a mixture thereof is used to dilute the monomer composition.

[0078] Preferably, step (y) includes the addition of a radical polymerization initiator.

[0079] Suitable radical polymerization initiators are, for example, azo initiators such as azobis-isobutyronitrile (AIBN), 2,2′-azobis(2-methylbutyronitrile) (AMBN) and 1,1-azobiscyclohexanecarbonitrile, and peroxide compounds such as methyl ethyl ketone peroxide, acetylacetone peroxide, dilauryl peroxide, tert-butylperoxy-2-ethylhexanoate, ketone peroxide, tert-butylperoctoate, methyl isobutyl ketone peroxide, cyclohexanone peroxide, dibenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxy-3,5,5-trimethylhexanoate, dicumyl peroxide, 1,1-bis(tert-butylperoxy)cyclohexane, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, cumyl hydroperoxide, tert-butyl hydroperoxide and bis(4-tert-butylcyclohexyl) peroxydicarbonate.

[0080] Preferably, the radical polymerization initiator is selected from the group consisting of 2,2′-azobis(2-methylbutyronitrile), 2,2-bis(tert-butylperoxy)butane, tert-butyl peroxy 2-ethylhexanoate, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butyl peroxybenzoate, and tert-butyl peroxy-3,5,5-trimethylhexanoate. Particularly preferred initiators are tert-butyl peroxy 2-ethylhexanoate and 2,2-bis(tert-butylperoxy)butane.

[0081] Preferably, the total amount of the radical polymerization initiator relative to the total mass of the monomer composition is 0.01 to 5% by mass, more preferably 0.02 to 1% by mass, and most preferably 0.05 to 0.5% by mass.

[0082] The total amount of the radical polymerization initiator may be added in one step, or the radical polymerization initiator may be added in several steps during the polymerization reaction. Preferably, the radical polymerization initiator is added in several steps. For example, a part of the radical polymerization initiator may be added to initiate radical polymerization, and a second part of the radical polymerization initiator may be added 0.5 to 3.5 hours after the first dosage.

[0083] Preferably, step (y) also includes the addition of a chain transfer agent. Suitable chain transfer agents are particularly oil-soluble mercaptans such as n-dodecyl mercaptan or 2-mercaptoethanol, or chain transfer agents from the terpene type such as terpinolene. Particularly preferred is the addition of n-dodecyl mercaptan.

[0084] Preferably, the total reaction time of the radical polymerization is 2 to 10 hours, more preferably 3 to 9 hours.

[0085] After completion of the radical polymerization, the resulting polymer is preferably further diluted to a desired viscosity with the above oil. Preferably, the polymer is diluted to a polymer concentration of 5 to 60% by mass, more preferably 10 to 50% by mass, and even more preferably 20 to 40% by mass.

[0086] Use of the polymer according to the present invention The present invention also relates to the use of the above polyalkyl (meth) acrylate polymer as an additive for a lubricant composition to improve the viscosity index and shear resistance of the lubricant composition. The polymer of the present invention can thereby be used as a viscosity index improver, which has high solubility in a lubricating oil composition and maintains excellent properties of the lubricating oil composition, so that it has excellent shear resistance while maintaining a very high viscosity index of the lubricant composition.

[0087] Composition containing the polymer according to the present invention The present invention also (i) one or more base oils, and (ii) one or more of the above polyalkyl (meth) acrylate polymers and relates to a composition containing the same.

[0088] The composition may be an additive composition containing the polymer (ii) according to the present invention and one or more base oils (i) as a diluent. This additive composition may be added to a lubricant as a viscosity index improver, for example. Typically, the additive composition contains a relatively large amount of the polymer according to the present invention.

[0089] The composition may also be a lubricating oil composition containing the polymer (ii) according to the present invention, one or more base oils (i), and optionally further additives (iii) described below. The lubricant composition can be used, for example, as a transmission fluid or an engine oil. Generally, the lubricant composition contains a smaller amount of the polymer according to the present invention compared to the above additive composition.

[0090] Therefore, the concentration of the polyalkyl (meth)acrylate according to the present invention in the lubricant (also referred to as the treatment rate) can vary within a wide range, for example, from 0.1 to 99.5% by mass, or from 0.5 to 99.5% by mass.

[0091] When the composition is used as an additive composition, based on the total mass of the additive composition, the amount of one or more base oils (component (i)) is preferably from 0.5 to 80% by mass, more preferably from 50 to 80% by mass, and the amount of the polymer (component (ii)) is preferably from 20 to 99.5% by mass, more preferably from 20 to 50% by mass.

[0092] When the composition is used as a lubricant composition, based on the total mass of the additive composition, the amount of the base oil (component (i)) is preferably from 80 to 99.9% by mass, more preferably from 85 to 99.5% by mass, and the amount of the polymer (component (ii)) is preferably from 0.1 to 20% by mass, more preferably from 0.5 to 15% by mass.

[0093] Preferably, the total amount of (i) and (ii) is 95 to 100% by mass.

[0094] The polymer of the present invention, its additive composition, and the lubricant composition containing the polymer according to the present invention are used advantageously in drive system lubricating oils (for example, manual transmission oils, differential gear oils, automatic transmission oils and belt-type continuously variable transmission oils, axle fluid formulations, dual clutch transmission oils, and hybrid dedicated transmission oils), hydraulic oils (for example, hydraulic oils for mechanical devices, power steering oils, shock absorber oils), engine oils (for gasoline engines and diesel engines) and industrial oil formulations (for example, wind turbines).

[0095] When the lubricant composition according to the present invention is used as an engine oil, preferably, based on the total mass of the lubricant composition, it contains 0.5% by mass to 10% by mass, more preferably 0.5% by mass to 8% by mass of the polymer according to the present invention, whereby according to ASTM D445, 4 mm 2 / s to 10 mm 2A kinematic viscosity at 100 °C occurs within the range of / s.

[0096] When the lubricant composition of the present invention is used as an automotive gear oil, preferably, based on the total mass of the lubricant composition, the polymer according to the present invention is contained in an amount of 0.5% by mass to 10% by mass, more preferably 0.5% by mass to 8% by mass, whereby according to ASTM D445, 2 mm 2 / s to 15 mm 2 A kinematic viscosity at 100 °C occurs within the range of / s.

[0097] When the lubricant composition of the present invention is used as an automatic transmission oil, preferably, based on the total mass of the lubricant composition, the polymer according to the present invention is contained in an amount of 0.5% by mass to 10% by mass, more preferably 0.5% by mass to 8% by mass, whereby according to ASTM D445, 2 mm 2 / s to 6 mm 2 A kinematic viscosity at 100 °C occurs within the range of / s.

[0098] The kinematic viscosity can be measured according to ASTM D445. Preferably, the kinematic viscosity is measured at temperatures of 100 °C and 40 °C.

[0099] The shear resistance is preferably evaluated by measuring the properties of the lubricant before and after applying shear to the lubricant according to JASO M347. Preferably, shear is measured using an ultrasonic shear stability tester conforming to JASO M347-4.5.1 (1-hour method).

[0100] The base oil (i) used in the composition preferably contains an oil having a lubricating viscosity. Such oils include natural oils and synthetic oils, oils derived from hydrocracking, hydrogenation, and hydro-finishing processes, unrefined oils, refined oils, re-refined oils, or mixtures thereof.

[0101] The base oil can also be defined as specified by the American Petroleum Institute (API) (see the April 2008 edition of “Appendix E - API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils”, section 1.3, subheading 1.3. “Base Stock Categories”).

[0102] API currently defines five groups of lubricant base stocks (API 1509, Annex E - API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils, September 2011). Groups I, II, and III are mineral oils classified by the amount of saturation and sulfur they contain and their viscosity index, Group IV is polyalphaolefin, and Group V is everything else, including, for example, ester oils. Table 1 below illustrates these API classifications.

[0103]

Table 1

[0104] The kinematic viscosity (KV 100 ) at 100 °C of a suitable base oil used to produce the lubricant composition according to the present invention is preferably in the range of 1 mm 2 / s to 10 mm 2 / s, more preferably 1 mm 2 / s to 8 mm 2 / s, even more preferably 1 mm 2 / s to 5 mm 2 / s, as per ASTM D445.

[0105] Other base oils that can be used according to the present invention are Fischer - Tropsch - derived base oils of Groups II - III.

[0106] Base oils derived from Fischer-Tropsch are known in the art. The term "derived from Fischer-Tropsch" means that the base oil is a synthetic product of the Fischer-Tropsch process or is derived from said synthetic product. Base oils derived from Fischer-Tropsch are sometimes referred to as GTL (gas to liquid) base oils. Suitable Fischer-Tropsch derived base oils that are convenient for use as the base oil in the lubricating composition of the present invention are, for example, those disclosed in European Patent Application Publication No. 0776959, European Patent Application Publication No. 0668342, International Publication No. 97 / 21788, International Publication No. 00 / 15736, International Publication No. 00 / 14188, International Publication No. 00 / 14187, International Publication No. 00 / 14183, International Publication No. 00 / 14179, International Publication No. 00 / 08115, International Publication No. 99 / 41332, European Patent Application Publication No. 1029029, International Publication No. 01 / 18156, International Publication No. 01 / 57166 and International Publication No. 2013 / 189951.

[0107] Particularly for transmission oil formulations, base oils of API Group III and mixtures of different Group III oils are used. In a preferred embodiment, the one or more base oils (i) are a base oil of API Group III or a mixture of base oils of API Group III.

[0108] The lubricant composition according to the present invention is further characterized by a low kinematic viscosity at temperatures of 40 °C or lower. The KV 40 is preferably less than 40 mm 2 / s, more preferably 20 to 40 mm 2 / s. The KV 40 is the kinematic viscosity at 40 °C and can be measured according to ASTM D445.

[0109] The lubricant composition preferably has a viscosity index of greater than 150, more preferably greater than 180. The viscosity index can be measured according to ASTM D2270.

[0110] The lubricant composition is preferably a gear oil or an engine oil.

[0111] The lubricant composition according to the present invention may contain, as component (iii), a further additive selected from the group consisting of a friction modifier, a dispersant, an antifoaming agent, a detergent, an antioxidant, a pour point depressant, an antiwear additive, an extreme pressure additive, a corrosion inhibitor, a dye, and mixtures thereof.

[0112] Suitable dispersants include poly(isobutylene) derivatives such as poly(isobutylene) succinimides (PIBSIs) including boronated PIBSIs, and ethylene-propylene oligomers having N / O functionality.

[0113] The dispersant (including the boronated dispersant) is preferably used in an amount of 0 to 5% by mass based on the total amount of the lubricant composition.

[0114] Suitable antifoaming agents are silicone oil, fluorosilicone oil, and fluoroalkyl ether.

[0115] The antifoaming agent is preferably used in an amount of 0.005 to 0.1% by mass based on the total amount of the lubricant composition.

[0116] Preferred detergents include metal-containing compounds such as phenoxides, salicylates, thiophosphonates, especially thiopyrophosphonates, thiophosphonates and phosphonates, sulfonates and carbonates. As the metal, these compounds may particularly contain calcium, magnesium and barium. These compounds may preferably be used in neutral or overbased form.

[0117] The detergent is preferably used in an amount of 0.2 to 1% by mass based on the total amount of the lubricant composition.

[0118] Suitable antioxidants include, for example, phenolic antioxidants and amine antioxidants.

[0119] Phenolic antioxidants include, for example, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,4′-methylenebis(2,6-di-tert-butylphenol), 4,4′-bis(2,6-di-t-butylphenol), 4,4′-bis(2-methyl-6-t-butylphenol), 2,2′-methylenebis(4-ethyl-6-t-butylphenol), 2,2′-methylenebis(4-methyl-6-t-butylphenol), 4,4′-butylidenebis(3-methyl-6-t-butylphenol), 4,4′-isopropylidenebis(2,6-di-t-butylphenol), 2,2′-methylenebis(4-methyl-6-nonylphenol), 2,2′-isobutylidenebis(4,6-dimethylphenol), 2,2′-methylenebis(4-methyl-6-cyclohexylphenol), 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-amyl-p-cresol, 2,6-di-t-butyl-4-(N,N′-dimethylaminomethylphenol), 4,4′-thiobis(2-methyl-6-t-butylphenol), 4,4′-thiobis(3-methyl-6-t-butylphenol), 2,2′-thiobis(4-methyl-6-t-butylphenol), bis(3-methyl-4-hydroxy-5-t-butylbenzyl)sulfide, bis(3,5-di-t-butyl-4-hydroxybenzyl)sulfide, n-octyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, n-octadecyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, 2,2′-thio[diethyl-bis-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]. Among these, bisphenolic antioxidants and phenolic antioxidants having an ester group are particularly preferred.

[0120] The amine-based antioxidant includes, for example, monoalkyldiphenylamine such as monooctyldiphenylamine and monononyldiphenylamine; dialkyldiphenylamine such as 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-dinonyldiphenylamine; polyalkyldiphenylamine such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine; naphthylamine, specifically α-naphthylamine, phenyl-α-naphthylamine and further alkyl-substituted phenyl-α-naphthylamine such as butylphenyl-α-naphthylamine, pentylphenyl-α-naphthylamine, hexylphenyl-α-naphthylamine, heptylphenyl-α-naphthylamine, octylphenyl-α-naphthylamine, nonylphenyl-α-naphthylamine. Among these, diphenylamine is more preferable than naphthylamine from the viewpoint of its antioxidant effect.

[0121] Suitable antioxidants may further be selected from the group consisting of compounds containing sulfur and phosphorus, such as metal dithiophosphates, such as zinc dithiophosphate (ZnDTP); "OOS triesters" = reaction products of dithiophosphoric acid with activated double bonds from olefins, cyclopentadiene, norbornadiene, α-pinene, polybutene, acrylic esters, maleic esters (ashless upon combustion); organic sulfur compounds, such as dialkyl sulfides, diaryl sulfides, polysulfides, modified thiols, thiophene derivatives, xanthates, thioglycol, thioaldehyde, sulfur-containing carboxylic acids, heterocyclic sulfur / nitrogen compounds, especially dialkyldimercaptothiadiazole, 2-mercaptobenzimidazole, zinc bis(dialkyldithiocarbamate) and methylenebis(dialkyldithiocarbamate); organic phosphorus compounds, such as triaryl and trialkyl phosphites; organic copper compounds; and phenoxides and salicylates based on overbased calcium and overbased magnesium.

[0122] The antioxidant is used in an amount of 0 to 15% by weight, preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, based on the total amount of the lubricant composition.

[0123] Pour point depressants include ethylene-vinyl acetate copolymers, chlorinated paraffin-naphthalene condensates, chlorinated paraffin-phenol condensates, polyalkyl (meth)acrylates, and polyalkylstyrenes. Polyalkyl (meth)acrylates having a weight average molecular weight of 5,000 to 200,000 g / mol are preferred.

[0124] The amount of the pour point depressant is preferably 0.1 to 5% by weight based on the total amount of the lubricant composition.

[0125] Preferred antiwear additives and extreme pressure additives are sulfur-containing compounds, such as zinc dithiophosphate, zinc di-C 3~12-Alkyldithiophosphates (ZnDTP), zinc phosphates, zinc dithiocarbamates, molybdenum dithiocarbamates, molybdenum dithiophosphates, disulfides, sulfurized olefins, sulfurized fats and oils, sulfurized esters, thiocarbonates, thiocarbamates, polysulfides; phosphorus-containing compounds such as phosphites, phosphates such as trialkyl phosphates, triaryl phosphates such as tricresyl phosphate, amine-neutralized monoalkyl and dialkyl phosphates, ethoxylated monoalkyl and dialkyl phosphates, phosphonates, phosphines, amine salts or metal salts of these compounds; sulfur- and phosphorus-containing antiwear agents such as thiophosphites, thiophosphates, thiophosphonates, amine salts or metal salts of these compounds.

[0126] The antiwear additive may be present in an amount of 0 to 3% by mass, preferably 0.1 to 1.5% by mass, more preferably 0.5 to 0.9% by mass, based on the total amount of the lubricant composition.

[0127] Preferred friction modifiers may include mechanically active compounds such as molybdenum disulfide, graphite (including fluorinated graphite), poly(trifluoroethylene), polyamides, polyimides; compounds that form an adsorption layer such as long-chain carboxylic acids, fatty acid esters, ethers, alcohols, amines, amides, imides; compounds that form a layer by tribochemical reaction such as saturated fatty acids, phosphoric acid and thiophosphoric acid esters, xanthates, sulfurized fatty acids; compounds that form a polymer-like layer such as ethoxylated dicarboxylic acid partial esters, dialkyl phthalates, methacrylates, unsaturated fatty acids, sulfurized olefins; and organometallic compounds such as molybdenum compounds (molybdenum dithiophosphates and molybdenum dithiocarbamates MoDTC) and combinations thereof with ZnDTPs, copper-containing organic compounds.

[0128] Some of the compounds listed above may satisfy multiple functions. For example, ZnDTP is not only mainly an antiwear additive and an extreme pressure additive, but also has the properties of an antioxidant and a corrosion inhibitor (here a metal passivator / inactivator).

[0129] The additives detailed above are described in detail, inter alia, in T. Mang, W. Dresel (eds.), “Lubricants and Lubrication”, 2001, Wiley-VCH, Weinheim, R.M. Mortier, S.T. Orszulik (eds.), “Chemistry and Technology of Lubricants”.

[0130] Preferably, the total concentration of one or more of the above additives (iii) is up to 20% by mass, more preferably 0.05% to 15% by mass, still more preferably 5% to 15% by mass, based on the total mass of the lubricant composition.

[0131] Preferably, the amounts of (i) to (iii) total 95 to 100% by mass, preferably 100% by mass in total, based on the total mass of the lubricant composition.

Examples

[0132] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, which are not intended to limit the scope of the present invention in any way.

[0133] Ellipsis C1AMA C1-alkyl methacrylate = methyl methacrylate (MMA) C 3n AMA n-C3-alkyl methacrylate = n-propyl methacrylate C 3i AMA i-C3-alkyl methacrylate = isopropyl methacrylate C4AMA C4-alkyl methacrylate = n-butyl methacrylate C 12 / 14AMA C 12 / 14 -alkyl methacrylate C 16 / 18 AMA C 16 / 18 -alkyl methacrylate CTA chain transfer agent (dodecyl mercaptan) f 分岐 Degree of branching Initiator tert-butyl peroxy-2-ethylhexanoate KV 40 Kinematic viscosity at 40 °C, measured according to ASTM D7042 KV 100 Kinematic viscosity at 100 °C, measured according to ASTM D7042 Macroalcohol of hydrogenated polybutadiene having a methacrylate functional group (M n = 2,000 g / mol) Macromonomer of hydrogenated polybutadiene having a methacrylate functional group (M n = 2,000 g / mol) M n Number average molecular weight M w Weight average molecular weight NB3020 Nexbase (registered trademark) 3020, 2.2 mm 2 KV of / s 100 Group II base oil from Neste having OEM partner trademark product manufacturer PDI Polydispersity index, M w / M n Molecular weight distribution calculated by Vis.loss Viscosity loss % (calculated based on KV before and after shearing according to the 1-hour method of JASO M347) 100 Calculated based on VI Viscosity index, measured according to ASTM D2270 API Group II base oil commercially available from Yubase3 SK Lubricants Co., Ltd., KV 100 is 3.1 mm 2 / s.

[0134] Test method The polymers according to the present invention and the comparative examples were characterized with respect to their molecular weights and PDI.

[0135] As described above, the weight average molecular weight (M w ) of the polymer is determined by gel permeation chromatography (GPC) using a polymethyl methacrylate calibration standard, under the following measurement conditions: Eluent: Tetrahydrofuran (THF) Operating temperature: 40 °C Column: The column set consists of 4 columns: PSS-SDV 100 Å 10 μm 8.0 × 50 mm, 2 PSS-SDV Linear XL 10 μm 8.0 × 300 mm, PSS-SDV 100 Å 10 μm 8.0 × 300 mm, all columns having an average particle size of 10 μm Flow rate: 1 mL / min Injection volume: 100 μL Equipment: Shodex GPC101 consisting of an autosampler, a pump, and a column oven Detector: Refractive index detector from Shodex.

[0136] As described above, the number average molecular weight M of the macromonomer n is determined by gel permeation chromatography (GPC) using a polybutadiene calibration standard (PSS Standards Service GmbH, Mainz, Germany) in accordance with DIN 55672-1, under the following measurement conditions: Eluent: Tetrahydrofuran (THF) containing 0.02 M 2-diethylaminoethylamine Operating temperature: 35 °C Column: The column set consists of 4 columns: SDV 106 Å, SDV 104 Å, and SDV 103 Å (PSS Standards Service GmbH, Mainz, Germany), all of which have a size of 300 × 8 mm and an average particle size of 10 μm Flow rate: 1 mL / min Injection volume: 100 μL Machine: Agilent 1100 series consisting of an autosampler, a pump, and a column oven Detector: A refractive index detector from the Agilent 1260 series.

[0137] The lubricant formulations containing the polymer according to the present invention and the comparative examples were characterized for their viscosity index (VI) according to ASTM D 2270, and their kinematic viscosity at 40 °C (KV 40 ) and kinematic viscosity at 100 °C (KV 100 ) according to ASTM D7042.

[0138] To show the shear stability of the lubricant formulations, the viscosity loss (vis loss) was calculated according to JASO M347. The shear stability was investigated for 1 hour using a sonic shear stability tester according to JASO M347.

[0139] Synthesis of macroalcohol (hydroxylated hydrogenated polybutadiene) MA-1 The macroalcohol was synthesized by anionic polymerization of 1,3-butadiene using butyllithium at 20 - 45 °C. When the desired degree of polymerization was reached, the reaction was stopped by the addition of propylene oxide, and lithium was removed by precipitation with methanol. Subsequently, the polymer was hydrogenated at a maximum of 140 °C and a pressure of 200 bar in the presence of a noble metal catalyst under a hydrogen atmosphere. After the hydrogenation was completed, the noble metal catalyst was removed, and the organic solvent was removed under reduced pressure.

[0140] Table 2 summarizes the characterization data of MA-1.

[0141]

Table 2

[0142] Synthesis of macromonomer MM-1 In a 2L stirring device equipped with a Servel type stirrer, an air inlet pipe, a thermocouple with a controller, a heating mantle, a column with an irregular packing of 3mm wire spirals, a steam distributor, a top thermometer, a reflux condenser and a cooling plate, 1,000 g of the above-mentioned macroalcohol is dissolved in methyl methacrylate (MMA) by stirring at 60 °C. 20 ppm of 2,2,6,6-tetramethylpiperidine-1-oxyl radical and 200 ppm of hydroquinone monomethyl ether are added to the solution. While passing air for stabilization, after heating to MMA reflux (bottom temperature about 110 °C), about 20 mL of MMA is distilled off for azeotropic drying. After cooling to 95 °C, LiOCH3 is added and the mixture is heated back to reflux. After a reaction time of about 1 hour, the top temperature decreased to about 64 °C due to methanol formation. The formed methanol / MMA azeotropic mixture is continuously distilled off until a constant top temperature of about 100 °C is re-established. At this temperature, the mixture is reacted for an additional 1 hour. For further work-up, most of the MMA was withdrawn under reduced pressure. The insoluble catalyst residues are removed by pressure filtration (Seitz T1000 depth filter).

[0143] Table 3 summarizes the amounts of macroalcohol, MMA and LiOCH3 used in the synthesis of macromonomer MM-1.

[0144]

Table 3

[0145] Synthesis of the polymer according to the present invention According to the present invention, examples (Examples 1 to 5) were prepared. Also, comparative examples (Comparative Examples 6* to 11*) were prepared (see the monomer compositions in Table 4 below).

[0146] Production methods of Examples 1 to 5 and Comparative Examples 6*, 9* to 11* The monomer mixture whose composition is shown in Table 4 was prepared using Nexbase 3020 and Hydroseal G232 H (KV of 1.0 cSt) 100) was diluted with a 1.3 / 98.7 mixture to make the concentration of the monomer in the oil 60% by mass. 50% by mass of the reaction mixture prepared as described above was charged into an apparatus equipped with a four-necked flask and a precision glass-surveyor type stirrer. After heating to 90 °C under nitrogen, 2,2-bis(tert-butylperoxy)butane initiator was added to the reaction mixture in the amount described in Table 5 to initiate the reaction. The same amount of initiator and Hydroseal G232 H was added to the remaining 50% of the reaction mixture to make the concentration of the monomer in the oil 40% by mass, and this was continuously added to the flask at 90 °C over 3 hours. After the dosing of the reaction mixture, the reaction was maintained at 90 °C for 1 hour, and 0.2% by mass of 2,2-bis(tert-butylperoxy)butane (relative to the amount of monomer) was added. The reaction mixture was stirred at 90 °C for a further 2 hours, 0.2% of 2,2-bis(tert-butylperoxy)butane (relative to the amount of monomer) was added, and then it was diluted with Hydroseal G232 H to a 35% by mass solution of the polymer in the oil, and the final VII (Examples 1 to 5 and Comparative Examples 6*, 9* to 11*) was obtained.

[0147] Production method of Comparative Example 7* The monomer mixture whose composition is shown in Table 4 is diluted with Nexbase 3020 to make the concentration of the monomer in the oil 60% by mass. 50% by mass of the reaction mixture prepared as described above is charged into an apparatus equipped with a four-necked flask and a precision glass Serber type stirrer. After heating to 90 °C under nitrogen, 2,2-bis(tert-butylperoxy)butane initiator in the amount described in Table 3 is added to the reaction mixture to initiate the reaction. The same amount of initiator and Nexbase 3020 is added to the remaining 50% of the reaction mixture to make the monomer concentration in the oil 40% by mass, and this is continuously added to the flask at 90 °C over 3 hours. After the dosing of the reaction mixture, the reaction is maintained at 90 °C for 1 hour, and 0.2% by mass (relative to the amount of monomer) of 2,2-bis(tert-butylperoxy)butane is added. The reaction mixture is stirred at 90 °C for another 2 hours, 0.2% (relative to the amount of monomer) of 2,2-bis(tert-butylperoxy)butane is added, and then it is diluted with Nexbase 3020 to a 30% by mass solution of the polymer in the oil to obtain the final VII (Comparative Example 7*).

[0148] Comparative Example 8 * Production method The apparatus equipped with a four-necked flask and a precision glass Serber type stirrer is charged with the monomer mixture shown in Table 4 containing the total amount of MM-1 and 50% by mass of the remaining monomers, and polymerization oil NB3020 is added to make the monomer concentration in the oil 60 wt%. After heating to 100 °C under nitrogen, the remaining monomer mixture and NB3020 containing tert-butylperoxy-2-ethylhexanoate and dodecyl mercaptan are added within 3 hours at a constant dosing rate so that the monomer concentration in the oil becomes 30% by mass at the end of the reaction. The reaction is maintained at 100 °C, and 0.2% (relative to the total amount of monomer) of 2,2-bis(tert-butylperoxy)butane is added 0.5 hour and 3.5 hours after the dosing of the polymerization initiator is completed. The reaction mixture is stirred at 100 °C overnight to obtain the final VII with a concentration of 30% by mass (Comparative Example 8*).

[0149]

Table 4

[0150] Evaluation of Viscosity Index Improver Candidates According to the present invention, C 3n AMA and / or C 3i To show the improvement effect in the shear resistance of the polymer synthesized using AMA, the corresponding lubricant formulations containing the polymer in the base oil were prepared, and the corresponding viscous losses were measured.

[0151] Lubricant formulations A to K were produced by mixing the components described in Table 5 below. All amounts of the components are given in mass % based on the total mass of the lubricant composition.

[0152] All polymers were blended with an ATF package (same fixed treatment rate) and a base oil of API Group III (Yubase 3). The KV 100 of the lubricant formulation was adjusted so that it became 5.0 cSt by adjusting the treatment rates of the polymer and Yubase 3. The kinematic viscosity data and viscosity losses of the lubricant formulations are shown in Table 5.

[0153] As shown in Table 5 below, the polymers according to the present invention exhibit a significantly improved viscosity index compared to the comparative examples while maintaining good shear stability according to the comparative examples. These results are surprising since those skilled in the art would expect that such high viscosity index values would not be able to maintain shear stability in the lubricant formulation. Surprisingly, a large amount of C 3n AMA and / or C 3i The polyalkyl (meth) acrylates according to the present invention containing AMA monomer units have been found to have the desired high viscosity index while still maintaining good shear stability when mixed in the lubricant formulation.

[0154]

Table 5

Claims

1. A polyalkyl (meth) acrylate polymer, as monomer a), one or more polybutadiene-based macromonomers having a number average molecular weight of 500 to 10,000 g / mol, based on the total mass of the monomer composition, 15 to 35% by mass, and as monomer b), n-propyl (meth) acrylate, isopropyl (meth) acrylate, or a mixture thereof, based on the total mass of the monomer composition, 40 to 85% by mass, and obtained by polymerizing a monomer composition containing A polyalkyl (meth) acrylate polymer having a weight average molecular weight (Mw) of 50,000 to 250,000 g / mol.

2. The polyalkyl (meth) acrylate polymer according to claim 1, having a weight average molecular weight (Mw) of 70,000 to 200,000 g / mol.

3. The polyalkyl (meth) acrylate polymer according to claim 1 or 2, wherein the total amount of the monomers a) and b) is at least 70% by mass based on the total mass of the monomer composition.

4. The polyalkyl (meth) acrylate polymer according to any one of claims 1 to 3, wherein the polybutadiene-based macromonomer has a number average molecular weight of 1,000 to 6,000 g / mol.

5. The polyalkyl (meth) acrylate polymer according to any one of claims 1 to 4, wherein the monomer composition further contains 0 to 30% by mass of one or more monomers c), and the monomer c) is selected from the group consisting of methyl (meth) acrylate, butyl (meth) acrylate, and mixtures thereof.

6. The monomer composition further contains 0 to 30% by mass of one or more monomers d) based on the total mass of the monomer composition. The monomer d) has 8 to 17 carbon atoms and is selected from the group consisting of styrene and substituted styrenes having an alkyl substituent in the side chain. The polyalkyl (meth)acrylate polymer according to any one of claims 1 to 5.

7. The monomer composition further contains 0 to 15% by mass of one or more monomers e) based on the total mass of the monomer composition. The monomer e) is a linear or branched C ７ - C ３０ alkyl (meth)acrylate. The polyalkyl (meth)acrylate polymer according to any one of claims 1 to 6.

8. The monomer composition further contains 0 to 10% by mass of one or more monomers f) based on the total mass of the monomer composition. The monomer f) is selected from the group consisting of (meth)acrylates of ether alcohols, aminoalkyl (meth)acrylates, aminoalkyl (meth)acrylamides, and mixtures thereof. The polyalkyl (meth)acrylate polymer according to any one of claims 1 to 7.

9. The monomer composition further contains 0 to 30% by mass of one or more monomers c) selected from the group consisting of methyl (meth)acrylate, butyl (meth)acrylate, and mixtures thereof, based on the total mass of the monomer composition. 0 to 30% by mass of one or more monomers d) having 8 to 17 carbon atoms and selected from the group consisting of styrene and substituted styrenes having an alkyl substituent in the side chain, based on the total mass of the monomer composition. 0 to 15% by mass of one or more monomers e) selected from linear or branched C7 - C30 alkyl (meth)acrylates, based on the total mass of the monomer composition. One or more monomers f) selected from the group consisting of (meth) acrylates of ether alcohols, aminoalkyl (meth) acrylates, aminoalkyl (meth) acrylamides, and mixtures thereof are contained in an amount of 0 to 10% by mass based on the total mass of the monomer composition. The polyalkyl (meth) acrylate polymer according to any one of claims 1 to 8, wherein the amounts of the monomers a), b), c), d), e) and f) in total are 95 to 100% by mass based on the total mass of the monomer composition.

10. The polyalkyl (meth) acrylate polymer according to any one of claims 1 to 9, having a polydispersity of 2.5 to 5.

0.

11. A method for producing a polyalkyl (meth) acrylate polymer, the method having the following steps: (x) A step of preparing a monomer composition according to any one of claims 1 to 10. (y) A step of initiating radical polymerization of the monomer composition.

12. A composition comprising the following: (i) One or more base oils, and (ii) One or more polyalkyl (meth) acrylate polymers according to any one of claims 1 to 10.

13. The one or more base oils have an ASTM D445 kinematic viscosity KV of 1.0 mm ２ / s to 5.0 mjm ２ / s. The composition according to claim 12. １００ The composition according to claim 12.

14. The composition is a lubricant composition containing 80 to 99.9% by mass of one or more base oils (i) and 0.1 to 20% by mass of the polyalkyl (meth) acrylate polymer (ii) based on the total mass of the composition. The composition according to claim 12 or 13.

15. Use of the polyalkyl (meth)acrylate polymer according to any one of claims 1 to 10 as an additive for a lubricant composition for improving the viscosity index and shear resistance of the lubricant composition.

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