Acrylate-olefin copolymer as a high-viscosity base fluid

Abstract

To provide highly shear-stable synthetic base fluids or lubricating oil additives which, in lubricant oil compositions, have a positive influence on oil solubility and component solubility, as well as on low-temperature performance.SOLUTION: Acrylate-olefin copolymers obtained from a monomer composition combining short olefins with specific acrylate monomers are able to meet strict low-temperature requirements for market lubricant formulations at lower polymer treat rates, without compromising on other performance parameters.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to acrylate-olefin copolymers and to a process for producing these copolymers. The present invention also relates to lubricant compositions comprising the aforementioned copolymers, and to the use of said copolymers as lubricant additives or synthetic base fluids in lubricating oil compositions, preferably in gear oil compositions, transmission oil compositions, hydraulic oil compositions, engine oil compositions, marine oil compositions, industrial lubricating oil compositions or greases.

Background Art

[0002] The present invention relates to the field of lubrication. Lubricants are compositions that reduce friction between surfaces. In addition to providing freedom of movement between two surfaces and reducing mechanical wear of said surfaces, lubricants can also inhibit corrosion of said surfaces and / or inhibit damage to said surfaces from heat or oxidation. Examples of lubricant compositions include, but are not limited to, engine oils, transmission oils, gear oils, industrial lubricating oils, greases and metalworking oils.

[0003] Lubricants typically contain a base fluid and variable amounts of additives. Conventional base fluids are hydrocarbons, for example mineral oils. The terms base oil and base fluid are commonly used interchangeably. Base fluid is used as a general term herein.

[0004] Depending on the intended use of the lubricant, a wide variety of additives can be combined with 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.

[0005] Typical non-polymer-based fluids are not very effective as lubricants because they have low viscosity and their viscosity decreases further at higher operating temperatures. Therefore, polymer additives are used to increase the viscosity of the base oil and reduce the change in viscosity with temperature. The term viscosity index (VI) is used to describe this change in viscosity with temperature. The lower the VI, the greater the change in viscosity with temperature, and vice versa. Therefore, a high VI is desirable for lubricant formulations. To improve VI, polymer additives or viscosity index improvers (VII) may be added to lubricant formulations.

[0006] It is well known in the art that alkyl acrylates are not recommended for VI improver applications, and that commercially available VI improvers are methacrylate-based. While there are publications (Rashad et al. J. of Petr. Sci. and Engineering 2012, 173-177; Evin et al. J. of Sol. Chem 1994, 325-338) and patents (International Publication No. 96 / 17517 (WO96 / 17517)), it is also generally known that the performance of polyacrylates as VI improvers is inferior to that of polymethacrylates. In particular, International Publication No. 96 / 17517 describes the unexpected discovery that poly(alkyl acrylate) esters typically fail to adequately reduce the effect of temperature on viscosity when used in working fluids.

[0007] A drawback of adding polymer additives to lubricant formulations is that these polymer additives are subjected to shear stress and mechanically degrade over time. Higher molecular weight polymers are better thickeners, but they are more susceptible to shear stress, which leads to polymer degradation. To reduce polymer degradation, the molecular weight of the polymer can be reduced, thereby obtaining a more shear-stable polymer. These shear-stable low molecular weight polymers are no longer extremely effective thickeners and must be used at higher concentrations in the lubricant to achieve the desired viscosity. These low molecular weight polymers typically have a molecular weight of less than 20,000 g / mol and are also called synthetic high-viscosity base fluids. High-viscosity base fluids are used to increase VI and to thicken lubricant formulations that have stringent shear stability requirements. A typical application is gear oil, which has extremely stringent requirements due to high mechanical stress and a wide temperature range during operation.

[0008] Typical products in this market are high-viscosity polyalphaolefins (PAOs) and metallocene polyalphaolefins (mPAOs), typically sold in a viscosity range of 40–300 cSt at 100°C (Choudary et al. Lubr. Sci. 2012, 23–44), and their key characteristic is their good handling properties in terms of viscosity, because these base fluids are actually polymers and possess an improved viscosity index. However, the nonpolar nature of the aforementioned PAO base oils, DI packages, and aged products is a drawback, because this low polarity can lead to low solubility in oil, which can subsequently cause problems.

[0009] It has already been stated that higher polarity is provided by copolymers of α-olefins and maleates (West German Patent Application Publication No. 3223694 (DE3223694)), copolymers of α-olefins and acrylates (West German Patent Application Publication No. 2243064 (DE2243064)), copolymers of α-olefins and methacrylates (European Patent Application Publication No. 0471266 (EP0471266)), or terpolymers based on the above monomers (International Publication No. 2020 / 078770 (WO2020 / 078770)). Alternatively, oil-compatible polyesters (International Publication No. 01 / 46350 (WO01 / 46350)), polyalkyl (meth)acrylates (German Patent Application Publication No. 102010028195 (DE102010028195)), or polyvinyl ethers (US Patent Application Publication No. 2013 / 0165360 (US2013 / 0165360)) can be used. A major advantage of using polar, high-viscosity base fluids is that polar, low-viscosity fluids, such as esters, do not need to be used as compatibilizers for the aforementioned polar lubricant additives. While polar, low-viscosity fluids are known to cause problems with coatings and seals, this is not as much of a concern with high-viscosity fluids.

[0010] Copolymers of various (meth)acrylates and olefins have been reported as suitable base fluids for use in industrial gear oils. For example, International Publication 2020 / 088770 (WO2020 / 088770) describes terpolymers made from (meth)acrylates, olefins, and maleates used in industrial gear oil formulations, although all examples are dodecene-based. Furthermore, International Publication 2020 / 200866 (WO2020 / 200866) and International Publication 2019 / 175300 (WO2019 / 175300) describe copolymers of alkyl (meth)acrylates and ethylenes, and their use in lubricants. However, even when these copolymers are mixed with excellent base oils in formulations, the reported low-temperature properties (pour points all above -40°C) require further improvement to meet market requirements for lubricant formulations.

[0011] U.S. Patent No. 6066603 discloses a highly branched copolymer derived from ethylene and one or more olefins, including C3-C20α-olefins such as propylene and 1-butene, and at least one polar monomer preferably selected from the group consisting of methyl acrylate, ethyl acrylate, tert-butyl acrylate, methyl methacrylate, methyl ethyl hydrate, ethyl methacrylate, ethyl ethyl hydrate, methyl vinyl ketone, and acrylamide. Very small amounts of the polar monomer are incorporated into the polymer (up to one polar moiety per 1000 Mn segment of the polymer). The polar monomer acts as branching end groups and provides the possibility of further functionalization. While it is stated that the polymer can be used as a fuel or lubricant additive, specific examples of lubricant compositions are not provided in the patent.

[0012] Olefin-acrylate copolymers for wax modification are also described in U.S. Patent Application Publication No. 2015 / 0307697 (US2015 / 0307697). The olefin-(meth)acrylate composition is designed such that either or both of the hydrocarbonyl groups of the (meth)acrylate or the α-olefin contain more than 16 and up to 50 carbon atoms. Among these, long wax-like side chains are included, which are undesirable in high-viscosity base stocks due to their crystallizing properties. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] International Publication No. 96 / 17517 [Patent Document 2] West German Patent Application Publication No. 3223694 [Patent Document 3] West German Patent Application Publication No. 2243064 [Patent Document 4] European Patent Application Publication No. 0471266 [Patent Document 5] International Publication No. 2020 / 078770 [Patent Document 6] International Publication No. 01 / 46350 [Patent Document 7] German Patent Application Publication No. 102010028195 Specification [Patent Document 8] U.S. Patent Application Publication No. 2013 / 0165360 [Patent Document 9] International Publication No. 2020 / 088770 [Patent Document 10] International Publication No. 2020 / 200866 [Patent Document 11] International Publication No. 2019 / 175300 [Patent Document 12] U.S. Patent No. 6066603 [Patent Document 13] U.S. Patent Application Publication No. 2015 / 0307697 Specification [Non-patent literature]

[0014] [Non-Patent Document 1] Rashad et al. J. of Petr. Sci. and Engineering 2012, 173-177 [Non-Patent Document 2] Evin et al. J. of Sol. Chem 1994, 325-338 [Non-Patent Document 3] Choudary et al. Lubr. Sci. 2012, 23-44 [Overview of the Initiative] [Problems that the invention aims to solve]

[0015] Therefore, the object of the present invention was to provide a highly shear-stable synthetic base fluid or lubricant additive that has a positive effect on oil solubility, component solubility, and low-temperature performance in a lubricant composition. Furthermore, the novel polymer should be able to thicken the oil to a desired viscosity. These highly shear-stable copolymers should also have a high viscosity index to reduce the effect of viscosity change with temperature. [Means for solving the problem]

[0016] The inventors of the present invention have surprisingly found that acrylate-olefin copolymers obtained from monomer compositions combining short olefins with specific acrylate monomers, as defined in claim 1, can meet the stringent low-temperature requirements of commercially available lubricant formulations at lower polymer processing rates without compromising other performance parameters. This advantage in processing rate makes the solution more commercially attractive. As demonstrated in the experimental section of the present invention, it was found that a specific weight ratio combination of the acrylate monomer as defined in claim 1 and the short-chain C4-C6α-olefin is decisive in achieving a combination of high VI and good low-temperature properties, which was unexpected.

[0017] Accordingly, a first aspect of the present invention is an acrylate-olefin copolymer as defined in claim 1 and its dependent claims.

[0018] A second aspect of the present invention is a method for producing an acrylate-olefin copolymer according to the present invention.

[0019] A third aspect of the present invention is a lubricant composition comprising at least one base oil and at least one acrylate-olefin copolymer according to the present invention.

[0020] A fourth aspect of the present invention is the use of these acrylate-olefin copolymers as lubricant additives or synthetic base fluids in lubricating oil compositions, preferably gear oil compositions, transmission oil compositions, hydraulic oil compositions, engine oil compositions, marine oil compositions, industrial lubricating oil compositions, or greases.

[0021] Detailed description of the invention The copolymer according to the present invention The present invention relates to a copolymer, wherein the copolymer is a) Based on the total weight of the copolymer, 70 to 95% by weight of formula (I) [ka] [In the formula, R1 means a linear or branched alkyl group having 4 to 18 carbon atoms, and is a C4 linear alkyl group, C6 to C 10 Linear alkyl groups, C8~C 18 Branched alkyl group, C 11 ~C 18 A monomer unit derived from an acrylate of a linear alkyl group or a mixture thereof, Here, the monomer units derived from the acrylate of formula (I) are, based on the total weight of the copolymer, 0-45% by weight of acrylate of formula (I) where R1 is a C4 linear alkyl group, 0-95% by weight, R1 is C6-C 10 A linear alkyl group, acrylate of formula (I), 0-95% by weight, R1 is C8-C 18 A branched alkyl group acrylate of formula (I), 0-45% by weight, R1 is C 11 ~C 18 A linear alkyl group acrylate of formula (I), or those mixtures Selected from, b) Based on the total weight of the copolymer, 5 to 30% by weight of formula (II) [ka] [wherein R2 means a linear alkyl group having 2 to 4 carbon atoms] A monomer unit derived from at least one non-functionalized α-olefin and The copolymer contains the above, and the copolymer has a weight-average molecular weight of 5,000 to 35,000 g / mol according to DIN 55672-1.

[0022] The terms "polymer" and "copolymer" are used synonymously to define copolymers according to the present invention.

[0023] According to the present invention, the copolymer of the present invention comprises 70 to 95% by weight of monomer unit a) derived from the acrylate monomer of formula (I), based on the total weight of the copolymer. According to one aspect of the present invention, it is preferred that the copolymer comprises 75 to 95% by weight, more preferably 80 to 95% by weight of monomer unit a) derived from the acrylate monomer of formula (I), based on the total weight of the copolymer.

[0024] Acrylate a) of formula (I) refers to an ester of acrylic acid and a linear or branched alcohol having 4 to 18 carbon atoms. This term includes individual acrylic acid esters with alcohols of a specific length, as well as mixtures of acrylic acid esters with alcohols of different lengths. Acrylate a) of formula (I) is selected from the group consisting of acrylates having a C4 linear alkyl group, a C6~C 10 linear alkyl group, a C8~C 18 branched alkyl group, a C 11 ~C 18 linear alkyl group, or mixtures thereof. Based on the total weight of the copolymer, the monomer units derived from the acrylate of formula (I) comprise 0 to 45% by weight, preferably 0 to 40% by weight, more preferably 0 to 30% by weight of the acrylate of formula (I) wherein R1 is a C4 linear alkyl group, 0 to 95% by weight of the acrylate of formula (I) wherein R1 is a C6~C 10 linear alkyl group, 0 to 95% by weight of the acrylate of formula (I) wherein R1 is a C8~C 18 branched alkyl group, 0 to 45% by weight of the acrylate of formula (I) wherein R1 is a C 11 ~C 18 linear alkyl group, or mixtures thereof.

[0025] Acrylate a) of formula (I) wherein R1 is a C4 linear alkyl group corresponds to butyl acrylate.

[0026] R1 is a C6~C 10 The most preferred acrylate a) of formula (I) having a linear alkyl group is n-octyl acrylate.

[0027] R1 is C8~C 18 The most preferred acrylate a) of formula (I), which is a branched alkyl group, is 2-ethylhexyl acrylate, 2-propylheptyl acrylate, isononyl acrylate, or a mixture thereof.

[0028] R1 is C 11 ~C 18 The most preferred acrylate a) of formula (I), which is a linear alkyl group, is lauryl acrylate.

[0029] The particularly preferred acrylate a) of formula (I) is selected from the group consisting of butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, isononyl acrylate, lauryl acrylate, or mixtures thereof.

[0030] According to the present invention, the copolymer comprises 5 to 30% by weight of monomer units derived from at least one unfunctionalized α-olefin of formula (II), based on the total weight of the copolymer, where R2 represents a linear alkyl group having 2 to 4 carbon atoms. According to one aspect of the present invention, it is preferable that the copolymer comprises 5 to 25% by weight, more preferably 5 to 20% by weight of monomer units b) derived from at least one unfunctionalized α-olefin of formula (II), based on the total weight of the copolymer.

[0031] The most preferred non-functionalized α-olefin b) of formula (II) is selected from the group consisting of butene, hexene, or mixtures thereof.

[0032] According to another aspect of the present invention, the copolymer is heated at 100°C to 1000 mm in accordance with ASTM D 445. 2 / s, more preferably 100-700 mm at 100°C according to ASTM D 445 2 / s, more preferably 100-500 mm at 100°C according to ASTM D 445 2 It is preferable to have a kinematic viscosity of / s.

[0033] According to another preferred embodiment of the present invention, the total content of monomer units derived from monomers a) and b) in the copolymer of the present invention is 80% by weight or more, more preferably 90% by weight or more, even more preferably 95% by weight or more, most preferably 98% by weight or more, and most preferably 100% by weight, based on the total weight of the copolymer.

[0034] According to the present invention, the copolymer has a weight-average molecular weight of 5,000 to 35,000 g / mol, preferably 7,000 to 25,000 g / mol, more preferably 8,000 to 25,000 g / mol, and even more preferably 10,000 to 25,000 g / mol, in accordance with DIN 55672-1.

[0035] In the present invention, the weight-average molecular weight (M) of the copolymer. w ) or number-average molecular weight (M n The following parameters were determined by gel permeation chromatography (GPC) using PMMA calibration standards in accordance with DIN 55672-1 under the following measurement conditions: Eluent: Tetrahydrofuran (THF) Operating temperature: 35℃ Columns: This column set consists of four columns: two SDV 106Å columns, one SDV 104Å column, and one SDV 103Å column (PSS Standards Service GmbH, Mainz, Germany), all with a size of 300 × 8 mm and an average particle size of 10 μm. Flow rate: 1mL / min Injection volume: 100 μL Equipment: Agilent 1100 series consisting of autosampler, pump, and column oven. Detection device: Refractive index detector from Agilent 1100 series.

[0036] Preferably, the copolymer of the present invention has an extremely low degree of crosslinking and a narrow molecular weight distribution, which further contributes to shear resistance. The low degree of crosslinking and the narrow molecular weight are reflected in the polydispersity index of the copolymer. Preferably, the polydispersity index (PDI) of the copolymer according to the present invention is in the range of 1.0 to 3.5, more preferably in the range of 1.5 to 3.0. A polydispersity index in the range of 1.0 to 3.5 is considered optimal for most industrial applications with respect to the shear resistance of the copolymer. The polydispersity index is the ratio (M) of the weight-average molecular weight to the number-average molecular weight. w / M n ) is defined as.

[0037] The copolymer of the present invention optionally contains monomer units derived from monomer c), selected from the list consisting of methacrylamide, fumarate, maleate, (meth)acrylate other than acrylate a), or mixtures thereof. Preferably, the amount of monomer units derived from monomer c) in the resulting copolymer of the present invention is 0 to 20% by weight, more preferably 0 to 10% by weight, even more preferably 0.1 to 5% by weight, and most preferably 0.5 to 3% by weight, based on the total weight of the copolymer. Particularly preferred monomer c) is di-2-ethylhexyl maleate, N-3-dimethylaminopropyl methacrylamide, di-2-ethylhexyl fumarate, or mixtures thereof.

[0038] 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.

[0039] According to another preferred embodiment of the present invention, the total content of monomer units derived from monomers a), b), and c) in the copolymer of the present invention is 90% by weight or more, more preferably 95% by weight or more, even more preferably 98% by weight or more, and most preferably 100% by weight, based on the total weight of the copolymer.

[0040] According to the present invention, the copolymer is a statistical copolymer, where the monomer units a), b) and optionally c) are randomly and sometimes unevenly distributed in the copolymer.

[0041] Surprisingly, it was observed that the aforementioned combination of monomer unit a) of formula (I) and short-chain α-olefin monomer unit b) of formula (II) in the copolymer can produce copolymers with excellent properties when used as additives or base fluids in lubricating oil formulations. As shown in the experimental section of the present invention, the acrylate-olefin copolymers of the present invention obtained from monomer compositions combining short olefins with specific acrylate monomers meet the stringent low-temperature requirements of commercially available lubricant formulations, even at low polymer processing rates, without compromising on other performance parameters. Unexpectedly, it was also found that specific weight ratio combinations of acrylate monomers as defined in claim 1 and short-chain C4-C6α-olefins are decisive in achieving a combination of high VI and good low-temperature properties.

[0042] The preferred copolymer of the present invention According to a preferred embodiment of the present invention, the copolymer is a) Based on the total weight of the copolymer, 70 to 95% by weight of formula (I) [ka] A monomer unit derived from an acrylate [wherein R1 means a linear or branched alkyl group having 4 to 18 carbon atoms], Here, the monomer units derived from the acrylate of formula (I) are, based on the total weight of the copolymer, 0-30% by weight of butyl acrylate, 0-95% by weight of n-octyl acrylate, 0-95% by weight of 2-ethylhexyl acrylate, 2-propylheptyl acrylate, isononyl acrylate, or mixtures thereof, and 0-45% by weight of lauryl acrylate or mixtures thereof Selected from, b) Based on the total weight of the copolymer, 5 to 30% by weight of formula (II) [ka] A monomer unit derived from at least one non-functionalized α-olefin [wherein R2 means a linear alkyl group having 2 to 4 carbon atoms], c) Based on the total weight of the copolymer, monomer units selected from the list consisting of methacrylamide, fumarate, maleate, acrylate other than a) or mixtures thereof, in an amount of 0 to 10% by weight. Includes, Furthermore, the copolymer has a weight-average molecular weight of 5,000 to 35,000 g / mol, preferably 7,000 to 25,000 g / mol, more preferably 8,000 to 25,000 g / mol, and most preferably 10,000 to 25,000 g / mol, according to DIN 55672-1.

[0043] According to a preferred embodiment, the total content of monomer units a), b), and c) is 95% by weight or more, more preferably 98% by weight or more, and even more preferably 100% by weight, based on the total weight of the copolymer.

[0044] Method for producing copolymer according to the present invention According to the present invention, the above polymer is produced by a method comprising the following steps: i) The step of preparing the above monomer composition, and ii) A step of initiating radical polymerization in the monomer composition.

[0045] Standard free radical polymerization is described in detail, among other things, in Ullmann's Encyclopedia of Industrial Chemistry, 6th edition. Generally, polymerization initiators and optionally chain transfer agents are used for this purpose.

[0046] The polymerization step (ii) can be carried out under standard pressure, reduced pressure, or increased pressure. Preferably, the polymerization is carried out in a pressure range from standard pressure to 50 bar, preferably from standard pressure to 40 bar. In relation to the present invention, the term "standard pressure" means ambient pressure or atmospheric pressure, rather than applied pressure.

[0047] For radical copolymerization of olefins and acrylates, the polymerization temperature is crucial. Generally, the copolymerization temperature is in the range of 110 to 160°C, preferably 120 to 140°C.

[0048] The polymerization step (ii) may be carried out with or without dilution in oil or any solvent. Preferably, the polymerization step (ii) is carried out without dilution in oil or any solvent.

[0049] Preferably, step (ii) includes the addition of a radical initiator. Preferably, the radical initiator is selected from di-tert-amyl peroxide, 2,2-di-(tert-butylperoxy)butane, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, or di-tert-butyl peroxide. Preferably, the total amount of the radical initiator relative to the total weight of the monomer mixture is 0.01 to 5% by weight, more preferably 0.1 to 1% by weight. Preferably, the entire amount of the radical initiator is added continuously during copolymerization reaction (ii).

[0050] Preferably, the copolymerization step (ii) is carried out by supplying the acrylate monomer a) and optionally the monomer c) or any other comonomer together with the initiator to the unfunctionalized α-olefin monomer b). Preferably, the total reaction time for the radical polymerization is 2 to 5 hours, more preferably 2 to 4 hours, and most preferably 3 hours.

[0051] In another preferred embodiment of the present invention, a third step iii) is optionally performed, which corresponds to a distillation step for removing the unreacted α-olefin monomer b). Preferably, any remaining unreacted α-olefin monomer b) is removed by distillation using a rotary evaporator at 130°C and a minimum pressure of 15 mbar.

[0052] lubricating oil composition As described above, the present invention also relates to a lubricating oil composition comprising at least one base oil and at least one copolymer as defined in the present invention.

[0053] The base oils mentioned above correspond to lubricating base oils, mineral oils, synthetic oils or natural oils, animal oils or vegetable oils, selected according to their intended use.

[0054] The base oils used in the formulation of the lubricating oil compositions according to the present invention include, for example, conventional base stocks selected from API (American Petroleum Institute) base stock categories known as Group I, Group II, Group III, Group IV, and Group V. The Group I and II base stocks are mineral oil materials (e.g., paraffinic and naphthenic oils) having a viscosity index of less than 120 (or VI). Group I is further distinguished from Group II in that the latter contains 90% or more saturated material, while the former contains less than 90% saturated material (i.e., 10% or more unsaturated material). Group III is considered the highest level mineral base oil with a viscosity index of 120 or more and a saturation level of 90% or more. Group IV base oils are polyalphaolefins (PAOs). Group V base oils are esters and all other base oils not included in Groups I-IV. These base oils can be used individually or in mixtures.

[0055] Preferably, the base oil contained in the lubricating oil composition of the present invention is selected from the group consisting of API Group II base oils, API Group III base oils, or mixtures thereof. Most preferably, the lubricating composition contains an API Group III base oil or a mixture thereof.

[0056] In a preferred embodiment of the present invention, the lubricating oil composition comprises, based on the total weight of the lubricating composition, 0.1 to 99.9% by weight, preferably 1 to 95% by weight, of at least one base oil and 0.1 to 99.9% by weight, preferably 5% to 99% by weight, of at least one copolymer according to the present invention.

[0057] The lubricating oil composition according to the present invention may contain any other additional additives suitable for use in the above formulation. These additives include additional viscosity index improvers, pour point depressants, dispersants, anti-emulsifiers, defoamers, lubricating additives, friction modifiers, antioxidants, detergents, pigments, corrosion inhibitors, and / or odorants.

[0058] Applications of the copolymer of the present invention The present invention also relates to the use of copolymers according to the present invention as lubricant additives or synthetic base fluids in lubricating oil compositions, preferably gear oil compositions, transmission oil compositions, hydraulic oil compositions, engine oil compositions, marine oil compositions, industrial lubricating oil compositions, or greases.

[0059] Experiment Section The present invention will be further described below in detail with reference to examples and comparative examples, but this is not intended to limit the scope of the invention. All percentages related to monomers or base fluids shown in the following table are weight percentages (wt%).

[0060] abbreviated form Anglamol 6043 Additive Package BA Butyl Acrylate But 1-Buten Brookfield viscosity measured at -40°C according to BF-40 ASTM D2983 BV (Volume Viscosity) Volume viscosity at 100°C according to BV100 ASTM D445 C2Acr C2 alkyl acrylate C4Acr C4 linear alkyl acrylate C6~C 10 Acr C6~C 10 Linear alkyl acrylate C8~C 18 b-Acr C8~C 18 Branched alkyl acrylate C 11 ~C 18 Acr C 11 ~C 18 Linear alkyl acrylate cSt mm in SI units 2 Centistokes equivalent to / s cP is centipoise, equivalent to mPa·s in SI units. DAPO di-tert-amyl peroxide DBPO di-tert-butylperoxide Dec 1 - Decen EA Ethyl Acrylate EHA 2-ethylhexyl acrylate Hex 1 - Hexene INA Isononyl Acrylate Initiator Tapered roller bearing shear stability test according to KRL CEC L-45-A-99 Kinematic viscosity measured according to KV ASTM D445 KV 40 Kinematic viscosity measured at 40°C according to ASTM D445 KV 100 Kinematic viscosity measured at 100°C according to ASTM D445 LA Lauryl acrylate or dodecyl acrylate M n number average molecular weight M w Weight average molecular weight nm measurement not performed nOA n-octylacrylate PDI polydispersity index PPD (Pour-Dose Depressant) Shear loss determined at 100°C after SL KRL (20-hour run at 60°C) VI Viscosity Index VPL 1-300 Evonik VISCOPLEX (登録商標) 1-300, Polyalkyl methacrylate pour point depressant Yubase 4 4mm 2 / s KV 100 Group III base oil from SK Lubricants containing Yubase 6 6mm 2 / s KV 100 Group III base oil from SK Lubricants containing Yubase 8 8mm 2 / s KV 100 Group III base oil from SK Lubricants containing Test method KV ASTM D445 VI ASTM D2270 KRL CEC L-45-A-99 BF ASTM D2983.

[0061] In this invention, the volume viscosity (BV) of the polymer (product obtained from the polymerization reaction) corresponds to the kinematic viscosity (KV) of the resulting polymerization product, as measured according to ASTM D445. Therefore, the volume viscosity (BV100) of the polymer was measured as the kinematic viscosity at 100°C according to ASTM D445, as shown in Table 2 below. The solubility of each polymer in oil was tested by mixing 20% ​​by weight of the polymer in 80% by weight of Yubase 4 base oil. A polymer is considered insoluble if a cloudy mixture or a two-phase mixture is obtained. The results of the solubility tests in oil for each polymer are also shown in Table 2 below. [Examples]

[0062] Synthesis 1 :Acrylate-hexene copolymer (Example 1) 6.99 g of DAPO (1.0 wt%) mixed with 707.8 g of EHA (relative to the acrylate in the feed) was slowly fed to 486.2 g of 1-hexene (solvent to olefin monomer 25:75) in 170.4 g of heptane under nitrogen at 130°C for 3 hours. After stirring for another hour, the resulting colorless, clear polymer was cooled and filtered under pressure using a filter aid. Subsequently, residual hexene was removed by distillation using a rotary evaporator at 130°C and a pressure of less than 15 mbar. The amount of monomer incorporated into the polymer was determined by NMR analysis.

[0063] Examples of Inventions 3 and 4, and Comparative Example 2 * ~5 * The following was prepared using the same method as in Invention Example 1, except that the amount of starting material and / or other reaction conditions were changed as listed in Tables 1 and 2. Invention Example 4 and Comparative Example 5 * Regarding this, the reaction mixture after the feed and stirring steps was heated at 140°C for 30 minutes before cooling. Furthermore, Comparative Example 4 * This was achieved using 2,2-di-(tert-butylperoxy)butane as an initiator, and in Comparative Example 3 * This was prepared using 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane as an initiator.

[0064] Synthesis 2 :Acrylate-butene copolymer (Example 2) 2.3 g of DAPO (0.3 wt%) mixed with 766 g of EHA (relative to the acrylate in the feed) was slowly fed to 457 g of 1-butene under nitrogen at 130°C for 3 hours. After stirring for another hour, the resulting colorless, clear polymer was cooled and filtered under pressure using a filter aid. Subsequently, the remaining monomer was removed by distillation using a rotary evaporator at 130°C and a pressure of less than 15 mbar. The amount of monomer incorporated into the polymer was determined by NMR analysis.

[0065] Synthesis 3 Acrylate-hexene copolymers using acrylate mixtures (Example 5) 4.63 g of DAPO (0.7 wt%), mixed with 335.7 g of EHA and 323.7 g of LA, was slowly fed to 511.4 g of 1-hexene (solvent to olefin monomer 25:75) in 184.9 g of heptane under nitrogen at 130°C for 3 hours. After stirring for another hour, the resulting colorless, clear polymer was cooled and filtered under pressure using a filter aid. Subsequently, residual hexene was removed by distillation using a rotary evaporator at 130°C and a pressure of less than 15 mbar. The amount of monomer incorporated into the polymer was determined by NMR analysis.

[0066] Examples 5-11 of the invention, and Comparative Example 6 * ~9 * The product was prepared in the same manner as in Invention Example 5, except that the amount of starting material and / or other reaction conditions were changed as listed in Tables 1 and 2. For Invention Examples 9 to 11, the reaction mixture after the feed and stirring steps was heated at 140°C for 30 minutes before cooling. Furthermore, Invention Example 9 was prepared using 2,2-di-(tert-butylperoxy)butane as the initiator.

[0067] Synthesis 4: Synthesis of acrylate-hexene copolymers with two-step initiator addition (Example 12) A total of 5.94 g of DAPO (0.7 wt%) relative to the acrylate in the feed) was used. One-quarter of the initiator was mixed with 536.3 g of 1-hexene and charged into the reactor. The remaining three-quarters of the initiator, mixed with 842.0 g of INA, was then slowly supplied to the reactor under nitrogen at 130°C for 3 hours. After stirring for another hour, the reaction mixture was heated at 140°C for 30 minutes. The resulting colorless, clear polymer was then cooled and filtered under pressure using a filter aid. Subsequently, residual hexene was removed by distillation using a rotary evaporator at 130°C and a pressure of less than 15 mbar. The amount of monomer incorporated into the polymer was determined by NMR analysis.

[0068] Invention Example 13 was prepared in the same manner as Invention Example 12, except that the amount of starting material and other reaction conditions were changed as listed in Tables 1 and 2.

[0069] Synthesis 5 :Acrylate-long chain olefin copolymer (Example 1) * ) 18 g of DBPO (0.3 wt% relative to the acrylate in the feed) dissolved in 6000 g of EHA was slowly fed to 1500 g of 1-decene under nitrogen at 160°C for 3 hours. After the feeding was complete and the mixture was stirred at 160°C for 2 hours, the resulting colorless, clear polymer was cooled. Subsequently, residual olefins were removed by distillation using a rotary evaporator at 160°C and a minimum pressure of 10 mbar. The amount of decene incorporated into the polymer was determined by gravimetric analysis, assuming the absence of residual acrylate monomers.

[0070] Further details regarding the synthesis procedures for the individual examples described above, along with the basic properties of the polymers, are provided in Tables 1 and 2. In relation to the present invention, the term “solvent to olefin monomer” refers to the approximate volume ratio of the solvent to all unfunctionalized α-olefin monomers. The term “olefin equivalent” is defined as the molar equivalent of the olefin to the acrylate. The α-olefin monomer is always charged into the reactor first. The acrylate monomer and the initiator are then supplied over a set period. For acrylate-olefin copolymers using acrylate mixtures, all acrylates were mixed with the initiator before being supplied to the olefin. The temperatures shown in Table 1 correspond to the reaction temperatures during the acrylate / initiator supply.

[0071] Compounds containing the inventive polymer and comparative polymer shown in Table 2 were then prepared in the amounts of the components shown in Tables 3 and 4. The properties of the different compound(s), such as viscosity index, kinematic viscosity, Brookfield viscosity, and shear loss, are also shown in Tables 3 and 4. The goal was to obtain compound(s) that met the SAE 75W-90 standard (SAE stands for Society of Automotive Engineers). Table 5 shows the properties of some compound(s) prepared using some of the comparative polymers from Table 2, but these do not meet the requirements for a 75W-90 compound.

[0072] Table 1: Polymerization conditions for the production of acrylate-olefin copolymers [Table 1]

[0073] [Table 2]

[0074] [Table 3]

[0075] [Table 4]

[0076] [Table 5]

[0077] As shown in Table 2 above, all of the inventive polymers according to the present invention are soluble in oil. In contrast, Comparative Example 2 uses some comparative polymers, for example, a large amount of C4 linear alkyl acrylate, or a shorter alkyl acrylate, for example, ethyl acrylate. * ~4 * It is insoluble in oil. Therefore, these comparative examples did not meet the requirements for solubility in oil and were not tested in the formulations.

[0078] As shown in Tables 3 and 4 above, 75W-90 formulations containing the inventive acrylate-olefin copolymer according to the present invention provide optimized viscosity-temperature characteristics. The inventive copolymer used in the formulation has a favorable combination of viscosity (KV40 and KV100), viscosity index (VI), low-temperature properties (BF), and shear stability (SL). For some inventive formulations, a reduced processing rate is achieved without negative effects on other formulation properties, particularly low-temperature viscosity (BF-40) and shear stability (SL 100°C), which are the most important parameters of the 75W-90 specification. To meet the requirements of the 75W-90 formulation, formulations containing a decene-containing copolymer, which is a longer-chain α-olefin (F-1 * Compared to the above, formulations using short-chain olefins such as hexene or butene-containing polymers as thickeners (F-1 and F-2) are observed to require less polymer.

[0079] Interestingly, C4 linear alkyl groups, C8~C 18 Branched alkyl group, C 11 ~C18 Combinations of three different alkyl acrylates from linear alkyl groups, for example, the polymers of Invention Examples 8 and 9, C6~C 10 Copolymers using only one alkyl acrylate having a linear alkyl group, for example, the inventive polymers Examples 3 and 4, and C8-C 18 Copolymers using only one alkyl acrylate having a branched alkyl group, such as the inventive polymer example 12, exhibit extremely low processing rates in 75W-90 formulations (F-9 and F-10, F-3 and F-4, and F-5, respectively).

[0080] A good high-viscosity base fluid requires a combination of several properties. A key criterion for high-performance gear oil is its low-temperature performance. Apart from its low viscosity dependence on temperature, which is also reflected in its VI, it is important that the polymer does not exhibit strong intermolecular interactions that lead to poor low-temperature performance.

[0081] Regarding the composition of the copolymer, acrylate-olefin copolymers using acrylate mixtures combining short-chain, long-chain, and branched acrylates allow for adjustment of the solubility in the base oil and the low-temperature properties (e.g., Table 2). This makes it possible to satisfy the requirements of the 75W-90 specification (Table 4). As described above, combinations of short-chain olefins and large amounts of short-chain acrylates (e.g., Table 2) * ~4 * ) tends to cause insolubility in the base oil (Yubase 4). Therefore, C4 and C according to the present invention 11 ~C 18 The defined range for alkyl acrylates must be met to ensure the achievement of the 75W-90 specification. For example, copolymers using EA / EHA and hexene (Example 6) * ) is oil-soluble, however, as shown in Table 5, it could not meet the low-temperature requirements for the 75W-90 formulation (F-3 * (BF-40 = 700,000 mPa·s). Furthermore, Comparative Example 7 *This means that an amount of acrylate having a C4 linear alkyl group in the copolymer that is higher than 45% by weight, more specifically 46.9% by weight, leads to a copolymer that is oil-soluble but does not function well at low temperatures (F-4 * This demonstrates that BF-40 = 178,000 mPa·s.

[0082] Large amounts of long-chain linear acrylate (C 11 ~C 18 Comparative acrylate-olefin copolymers, including linear alkyl acrylates, such as lauryl acrylate, exhibit poor low-temperature properties because these copolymers are prone to crystallization (Comparative Example 5). * and F-2 * Even in combination with short-chain or branched alkyl acrylates, the incorporation of more than 45% by weight of lauryl acrylate in the copolymer leads to extremely poor low-temperature properties in the corresponding 75W-90 formulation. Comparative formulation F-5 in Table 5. * and F-6 * As shown in [reference], a high content of long linear side chains having more than 8 carbon atoms in the acrylate monomer unit results in extremely poor low-temperature performance (solid at BF -40°C), despite a high VI (>185). Therefore, a good combination of high VI and good low-temperature performance is not achieved. Surprisingly, copolymers having a lauryl acrylate content according to the present invention meet the requirements of 75W-90 formulations (see, for example, Inventive Polymer Examples 5-7 and corresponding Formulation Examples F-6-F-8), which demonstrates that the range of acrylate as defined in claim 1 is essential for obtaining polymers with good properties.

[0083] Embodiments of the present invention are as follows: 1. A copolymer, a) Based on the total weight of the copolymer, 70 to 95% by weight of formula (I) [ka] [In the formula, R1 means a linear or branched alkyl group having 4 to 18 carbon atoms, and is a C4 linear alkyl group, C6 to C 10 Linear alkyl groups, C8~C 18 Branched alkyl group, C 11 ~C 18 A monomer unit derived from an acrylate of a linear alkyl group or a mixture thereof, Here, based on the total weight of the copolymer, monomer units derived from the acrylate of formula (I) are 0 to 45% by weight of the acrylate of formula (I) where R1 is a C4 linear alkyl group, and 0 to 95% by weight of the acrylate of formula (I) where R1 is a C6-C4 linear alkyl group. 10 Linear alkyl group acrylate of formula (I), 0-95% by weight, where R1 is C8-C 18 A branched alkyl group acrylate of formula (I), 0-45% by weight, where R1 is C 11 ~C 18 Selected from acrylates of formula (I) which are linear alkyl groups, or mixtures thereof, b) Based on the total weight of the copolymer, 5 to 30% by weight of formula (II) [ka] [wherein R2 means a linear alkyl group having 2 to 4 carbon atoms] A monomer unit derived from at least one non-functionalized α-olefin and Includes, The copolymer having a weight-average molecular weight of 5,000 to 35,000 g / mol in accordance with DIN 55672-1.

[0084] 2. The copolymer according to Embodiment 1, wherein the copolymer contains 75 to 95% by weight, preferably 80 to 95% by weight, of monomer units a) derived from the acrylate monomer of formula (I), based on the total weight of the copolymer.

[0085] 3. The copolymer according to Embodiment 1 or 2, wherein the copolymer contains 5 to 25% by weight, preferably 5 to 20% by weight, of monomer units b) derived from at least one non-functionalized α-olefin of formula (II), based on the total weight of the copolymer.

[0086] 4. The copolymer is heated at 100°C for 100-1000 mm in accordance with ASTM D 445. 2 / s, preferably 100-700 mm at 100°C according to ASTM D 445 2 / s, more preferably 100-500 mm at 100°C according to ASTM D 445 2 A copolymer according to any one of the embodiments, having a kinematic viscosity of / s.

[0087] 5. The copolymer according to any one of the embodiments, wherein the non-functionalized α-olefin b) of formula (II) is selected from the group consisting of butene, hexene, or mixtures thereof.

[0088] 6. The copolymer according to any one of the embodiments, wherein the amount of acrylate of formula (I), in which R1 is a C4 linear alkyl group, is 0 to 40% by weight, preferably 0 to 30% by weight, based on the total weight of the copolymer.

[0089] 7. The copolymer according to any one of the embodiments, wherein the acrylate a) of formula (I) is selected from the group consisting of butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, isononyl acrylate, lauryl acrylate, or a mixture thereof.

[0090] 8. The copolymer according to any one of the embodiments, wherein the copolymer contains 0 to 20% by weight, preferably 0 to 10% by weight, of monomer units derived from monomer c), selected from the list of (meth)acrylates other than methacrylamide, fumarate, maleate, and acrylate a), or mixtures thereof, based on the total weight of the copolymer.

[0091] 9. The copolymer according to any one of the embodiments, wherein the total amount of monomer units derived from monomers a) and b) in the copolymer is 80% by weight or more, preferably 90% by weight or more, based on the total weight of the copolymer.

[0092] 10. The copolymer according to Embodiment 8 or 9, wherein the total amount of monomer units derived from monomers a), b), and c) in the copolymer is 90% by weight or more, preferably 95% by weight or more, and more preferably 100% by weight, based on the total weight of the copolymer.

[0093] 11. The copolymer according to any one of the embodiments, wherein the copolymer has a weight-average molecular weight of 7,000 to 25,000 g / mol, preferably 10,000 to 25,000 g / mol, according to DIN 55672-1.

[0094] 12. The copolymer according to any one of Embodiments 1 to 11, wherein the copolymer has a polydispersity index of 1.0 to 3.5, preferably 1.5 to 3.0.

[0095] 13. A method for producing a copolymer as defined in any one of Embodiments 1 to 12, wherein the method comprises the following steps: i) Steps to prepare the monomer composition, ii) A step of initiating radical polymerization in the monomer composition to obtain the copolymer. The method, including the method described above.

[0096] 14. A lubricant composition comprising one or more base oils and at least one copolymer described in any one of Embodiments 1 to 12.

[0097] 15. Use of copolymers defined in any one of Embodiments 1 to 12 as lubricant additives or synthetic base fluids in lubricant compositions, preferably gear oil compositions, transmission oil compositions, hydraulic oil compositions, engine oil compositions, marine oil compositions, industrial lubricant compositions, or greases.

Claims

1. It is a copolymer, a) Based on the total weight of the copolymer, 70 to 95% by weight of formula (I) 【Chemistry 1】 [In the formula, R １ This means a linear or branched alkyl group having 4 to 18 carbon atoms, and C ４ Linear alkyl group, C ６ ~C １０ Linear alkyl group, C ８ ~C １８ Branched alkyl group or C １１ ~C １８ A monomer unit derived from an acrylate [selected from the group consisting of linear alkyl groups], Here, the monomer units derived from the acrylate of formula (I) above are, based on the total weight of the copolymer, 0 to 45% by weight of R １ is C ４ an acrylate of formula (I) which is a linear alkyl group, 0 to 95% by weight of R １ is C ６ to C １０ an acrylate of formula (I) which is a linear alkyl group, 0 to 95% by weight of R １ is C ８ to C １８ an acrylate of formula (I) which is a branched alkyl group, 0 to 45% by weight of R １ is C １１ to C １８ an acrylate of formula (I) which is a linear alkyl group, or a mixture thereof, selected from b) Based on the total weight of the copolymer, 5 to 30% by weight of formula (II) 【Chemistry 2】 [In the formula, R ２ [This refers to a monomer unit derived from at least one non-functionalized α-olefin, which means a linear alkyl group having 2 to 4 carbon atoms] Includes, The copolymer having a weight-average molecular weight of 5,000 to 35,000 g / mol in accordance with DIN 55672-1.

2. The copolymer according to claim 1, wherein the copolymer contains 75 to 95% by weight of monomer units a) derived from the acrylate monomer of formula (I), based on the total weight of the copolymer.

3. The copolymer according to claim 1 or 2, wherein the copolymer contains 5 to 25% by weight of monomer units b) derived from at least one non-functionalized α-olefin of formula (II), based on the total weight of the copolymer.

4. The copolymer is subjected to a heating process of 100 to 1000 mm at 100°C according to ASTM D 445. ２ The copolymer according to claim 1 or 2, having a kinematic viscosity of / s.

5. The copolymer according to claim 1 or 2, wherein the non-functionalized α-olefin b) of formula (II) is selected from the group consisting of butene, hexene, or mixtures thereof.

6. The aforementioned R １ C ４ The copolymer according to claim 1 or 2, wherein the amount of acrylate of formula (I), which is a linear alkyl group, is 0 to 40% by weight based on the total weight of the copolymer.

7. The copolymer according to claim 1 or 2, wherein the acrylate a) of formula (I) is selected from the group consisting of butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, isononyl acrylate, lauryl acrylate, or a mixture thereof.

8. The copolymer according to claim 1 or 2, wherein the copolymer comprises 0 to 20% by weight, based on the total weight of the copolymer, monomer units derived from monomer c), selected from the list consisting of (meth)acrylates other than methacrylamide, fumarate, maleate, and acrylate a), or mixtures thereof.

9. The copolymer according to claim 1 or 2, wherein the total amount of monomer units derived from monomers a) and b) in the copolymer is 80% by weight or more, based on the total weight of the copolymer.

10. The copolymer according to claim 8, wherein the total amount of monomer units derived from monomers a), b), and c) in the copolymer is 90% by weight or more, based on the total weight of the copolymer.

11. The copolymer according to claim 1 or 2, wherein the copolymer has a weight-average molecular weight of 7,000 to 25,000 g / mol according to DIN 55672-1.

12. The copolymer according to claim 1 or 2, wherein the copolymer has a polydispersity index of 1.0 to 3.

5.

13. A method for producing a copolymer as defined in claim 1 or 2, wherein the method comprises the following steps: i) Steps to prepare the monomer composition, ii) A step of initiating radical polymerization in the monomer composition to obtain the copolymer. The method, including the method described above.

14. A lubricant composition comprising one or more base oils and at least one copolymer according to claim 1 or 2.

15. Use of the copolymer defined in claim 1 or 2 as a lubricant additive or synthetic base fluid in a lubricating oil composition.

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