Lubricant formulations with acrylate-olefin copolymers as high viscosity base fluids

Abstract

The present invention relates to lubricant formulations comprising a base oil and a functionalized acrylate-olefin copolymer, as well as to processes for preparing these lubricant formulations. The invention also relates to the lubricant formulation comprising a base oil and a functionalized acrylate-olefin copolymer as a lubricant formulation, the invention also relates to the use of the functionalized acrylate-olefin copolymer as a lubricant formulation, preferably as a gear oil lubricating composition, a transmission oil lubricating composition, a hydraulic oil lubricating composition, an engine oil lubricating composition, a marine oil lubricating composition, an industrial lubricating oil composition or a grease, by using the functionalized acrylate-olefin copolymer of the invention in the lubricant formulation.

Description

Technical Field

[0001] This invention relates to lubricant formulations comprising a base oil and a functionalized acrylate-olefin copolymer, and methods for preparing such lubricant formulations. The invention also relates to the use of said lubricant formulations comprising a base oil and a functionalized acrylate-olefin copolymer as lubricant formulations, preferably as gear oil lubricating compositions, transmission oil lubricating compositions, hydraulic oil lubricating compositions, engine oil lubricating compositions, marine oil lubricating compositions, industrial lubricating oil compositions, or greases, achieved by using the functionalized acrylate-olefin copolymer of the present invention in said lubricant formulation. Background Technology

[0002] This invention relates to the field of lubrication. A lubricant is a composition that reduces friction between surfaces. In addition to allowing freedom of movement between two surfaces and reducing mechanical wear, a lubricant can also inhibit surface corrosion and / or inhibit damage to the surface due to heat or oxidation. Examples of lubricant compositions include, but are not limited to, engine oils, transmission fluids, gear oils, hydraulic fluids, industrial lubricants, greases, and metalworking fluids.

[0003] Lubricants typically contain a base fluid and variable additives. A common base fluid is a hydrocarbon, such as mineral oil. The terms "base oil" or "base fluid" are often used interchangeably. In this document, "base fluid" is used as a general term.

[0004] Depending on the intended use of the lubricant, various additives can be combined with the base fluid. Examples of lubricant additives include, but are not limited to, viscosity index improvers, thickeners, pour point depressants, oxidation inhibitors, corrosion inhibitors, dispersants, high-pressure additives, defoamers, and metal passivators.

[0005] Typical non-polymer base fluids are less effective as lubricants because of their low viscosity, which decreases further at higher operating temperatures. Therefore, polymeric additives are used to thicken these base oils and reduce the change in viscosity with temperature. The term "viscosity index" (VI) describes this change in viscosity with temperature. The lower the VI, the greater the change in viscosity with temperature, and vice versa. Therefore, lubricant formulations require a high VI. To improve the VI, polymeric additives or viscosity index improvers (VII) can be added to the lubricant formulation.

[0006] It is well known in the art that alkyl acrylates are not recommended for VI modifier applications, and commercial VI modifiers are typically based on methacrylates. While there are literature (Rashad et al., J. of Petr. Sci. and Engineering 2012, 173-177; Evin et al., J. of Sol. Chem 1994, 325-338) and patents (WO96 / 17517), it is generally known that polyacrylates perform inferiorly to polymethacrylates as VI modifiers in those aspects. Specifically, as mentioned in WO96 / 17517, it has been unexpectedly found that alkyl acrylates, when used in the hydraulic fluids, generally do not adequately reduce the effect of temperature on viscosity.

[0007] The disadvantage of adding polymeric additives to lubricant formulations is that they will experience shear stress and mechanically degrade over time. Higher molecular weight polymers are better thickeners, but are more susceptible to shear stress, leading to polymer degradation. To reduce the amount of polymer degradation, the molecular weight of the polymer can be reduced, resulting in a more shear-stable polymer. However, these shear-stable low molecular weight polymers are no longer very effective thickeners and must be used in higher concentrations in the lubricant to achieve the desired viscosity. These low molecular weight polymers typically have a molecular weight below 20,000 g / mol and are also known as synthetic high-viscosity base fluids. High-viscosity base fluids are used to enhance viscosity (VI) and thicken lubricant formulations with stringent shear stability requirements. A typical application is gear oils, which have very demanding requirements due to the high mechanical stress and wide temperature range during operation.

[0008] Typical products in this market are high-viscosity polyalphaolefins (PAOs) and metallocene polyalphaolefins (mPAOs), typically sold at 100°C in viscosity ranges from 40 to 300 cSt (Choudary et al., Lubr. Sci. 2012, 23-44). Their key characteristic is good processability in terms of viscosity, as these base fluids are polymeric in nature and offer an improved viscosity index. However, the non-polar nature of the PAO base oils is a drawback, as it can lead to poor solubility in DI packages and aged products, potentially causing subsequent problems.

[0009] High polarity has been described through copolymers of α-olefins and maleates (DE3223694), copolymers of α-olefins and acrylates (DE2243064), copolymers of α-olefins and methacrylates (EP0471266), or terpolymers based on the aforementioned monomers (WO2020 / 078770). Another example is EP4015604, which describes an acrylate-olefin copolymer used as a high-viscosity base oil or lubricant additive in lubricating oil compositions. Compared to methacrylate-olefin copolymers and pure polyacrylates, the resulting lubricating oil compositions exhibit good low-temperature performance and a good viscosity index level. The aforementioned literature does not address issues of dispersibility and sludge deposition.

[0010] WO2017 / 139572 relates to copolymers prepared by reacting the following substances: (1) unactivated olefins, (2) activated olefins, and (3) hydroxyl-functionalized activated olefins and / or hydroxyl-functionalized unactivated olefins. These copolymers are described as being well-suited for use in optically transparent, pressure-sensitive, polyurethane, and / or barrier adhesives.

[0011] Dispersant additives can prevent sludge deposition, contribute to better ratings in tests, and ultimately extend the life of the finished lubricant. The disadvantage of dispersing sludge is an increase in the viscosity of the lubricant. Keeping this viscosity increase as low as possible is a key performance parameter for dispersants. Typical dispersants include, for example, terminally functionalized polyisobutylene (PIB) oligomers. PAMA, with nitrogen functionality, is also well-known as a dispersant additive (see, for example, US2015 / 0274875).

[0012] There remains a need to provide highly shear-stable synthetic base fluids or lubricating oil additives that positively influence oil solubility, component solubility, and low-temperature performance in lubricating oil compositions. Furthermore, the new products should not only thicken the oil to the desired viscosity but also improve the sludge deposition and dispersing properties of the resulting lubricating oil compositions. Summary of the Invention Invention Overview

[0014] The inventors of this invention have surprisingly discovered that, as defined in claim 1, a hydroxyl-functionalized acrylate-olefin copolymer containing a certain amount of hydroxyl-functionalized (meth)acrylate can very effectively thicken oil to the desired viscosity, while simultaneously improving the sludge deposition properties and dispersing properties of the resulting lubricating oil composition. As illustrated in the experimental section of this invention, it has been unexpectedly discovered that the acrylate monomer as defined in claim 1 and C8-C... 14A specific weight ratio combination of α-olefin and hydroxyl-functionalized (meth)acrylate monomers is crucial for achieving a combination of good thickening properties and excellent reduction in sludge deposition, while still maintaining good low-temperature performance. Furthermore, these copolymers are highly shear-stable and have a high viscosity index, which helps to reduce the effect of viscosity changes with temperature.

[0015] Therefore, a first aspect of the present invention is a lubricant formulation comprising a base oil and a hydroxy-functionalized acrylate-olefin copolymer comprising hydroxy-functional (meth)acrylate monomer units as defined in claim 1 and its dependent claims.

[0016] A second aspect of the present invention is a method for preparing a lubricant formulation according to the present invention.

[0017] A third aspect of the invention is a method for thickening a lubricant formulation and improving its dispersibility and / or reducing sludge deposition, which is achieved by adding the hydroxyl-functionalized acrylate-olefin copolymer according to the invention as a lubricant additive or a synthetic base fluid to the lubricant formulation. Invention Details

[0019] Lubricant formulation according to the present invention

[0020] This invention relates to lubricant formulations comprising a base oil and a hydroxyl-functionalized acrylate-olefin copolymer.

[0021] The copolymer described herein has a weight-average molecular weight of 5,000 to 30,000 g / mol according to DIN 55672-1 and comprises:

[0022] a) Based on the total weight of the copolymer, 60 to 99.8% by weight of monomer units derived from at least one acrylate of formula (I),

[0023] (I)

[0024] R1 refers to a straight-chain or branched alkyl group having 8 to 15 carbon atoms.

[0025] b) Based on the total weight of the copolymer, 0.1 to 39.9% by weight of monomer units derived from at least one nonfunctionalized α-olefin of formula (II),

[0026] (II)

[0027] R2 refers to a straight-chain alkyl group having 8 to 14 carbon atoms, and

[0028] c) Based on the total weight of the copolymer, 0.1 to 5% by weight of monomer units derived from at least one hydroxyl-functional (meth)acrylate monomer c),

[0029] and

[0030] The lubricant formulation has a content of less than 100% of the hydroxyl-functional (meth)acrylate monomer c) in the formulation, calculated according to formula (III):

[0031] [weight% of monomer c)] × TR < 100 (III)

[0032] Wherein [weight% of monomer c)] is the total weight content of monomer c) in the polymer, and TR is the polymer treatment rate in the lubricant formulation, expressed as a weight percentage.

[0033] The terms "polymer" and "copolymer" are used interchangeably to define copolymers according to the present invention.

[0034] The terms “lubricant formulation” and “lubricating oil composition” are used interchangeably to define the lubricant formulation according to the present invention.

[0035] In this invention, the term "alkyl methacrylate" refers to an ester of methacrylic acid, and the term "alkyl acrylate" refers to an ester of acrylic acid. The term "(meth)acrylate" refers to an ester of acrylic acid, an ester of methacrylic acid, or a mixture of an ester of acrylic acid and an ester of methacrylic acid.

[0036] In formula (III) above, the polymer dosage (TR) corresponds to the total amount of polymer in the lubricant formulation, expressed as a weight percentage, based on the total weight of the lubricant formulation.

[0037] The base oil corresponds to a lubricant base oil, namely a mineral oil, synthetic oil, or natural oil, animal oil, or vegetable oil, which is suitable for its use / selected according to the intended use.

[0038] Base oils used to formulate lubricating oil compositions according to the present invention include, for example, conventional base oils selected from API (American Petroleum Institute) base oil categories, which are known as Group I, Group II, Group III, Group IV, and Group V. Group I and Group II base oils are mineral oil materials (e.g., alkane oils and cycloalkane oils) with a viscosity index (or VI) less than 120. A further distinction between Group I and Group II is that the latter contains more than 90% saturated material, while the former contains less than 90% saturated material (i.e., more than 10% unsaturated material). Group III is considered to be the highest level of mineral base oil with a VI greater than or equal to 120 and a saturation level greater than or equal to 90%. Group IV base oils are polyalphaolefins (PAOs). Group V base oils are esters and no other base oils included in Groups I through IV. These base oils can be used alone or as mixtures.

[0039] Preferably, the base oil included 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, API Group IV base oils, or mixtures thereof. Most preferably, the lubricating oil composition comprises API Group III base oils or mixtures thereof.

[0040] Preferably, based on the total weight of the lubricant formulation, the lubricant formulation contains 0.1 to 99.9% by weight, more preferably 3 to 99% by weight, of the hydroxyl-functionalized acrylate-olefin copolymer according to the invention.

[0041] In a preferred embodiment of the invention, the lubricant formulation comprises, based on the total weight of the lubricating composition, 0.1 to 99.9% by weight, preferably 1 to 97% by weight, at least one base oil and 0.1 to 99.9% by weight, preferably 3% to 99% by weight, at least one copolymer according to the invention.

[0042] All the preferred aspects of the polymer, base oil, and quantity listed above apply to this lubricating oil composition.

[0043] The lubricating oil compositions according to the invention may also contain any other additional additives suitable for formulation. These additives include additional viscosity index improvers, pour point depressants, dispersants, demulsifiers, defoamers, lubricating additives, friction modifiers, antioxidants, detergents, dyes, corrosion inhibitors, and / or odorants.

[0044] According to a preferred aspect of the invention, based on the total weight of the lubricant composition, the total content of the copolymer and base oil according to the invention in the lubricant composition is 90% by weight or higher, more preferably 95% by weight or higher.

[0045] Within the meaning of this invention, the monomer composition corresponds to the monomers used to prepare the polymer according to the invention (excluding other reactants, such as initiators and stabilizers).

[0046] According to the present invention, based on the total weight of the copolymer, the copolymer of the present invention comprises 60 to 99.8% by weight of monomer unit a of acrylate monomer derived from formula (I). Preferably, based on the total weight of the copolymer, the copolymer comprises 65.5 to 95% by weight, more preferably 74.2 to 90% by weight of monomer unit a of acrylate monomer derived from formula (I).

[0047] Acrylates of formula (I) a) refer to esters of acrylic acid with straight-chain or branched alcohols having 8 to 15 carbon atoms. The term covers single acrylates of alcohols having a specific length, and also covers mixtures of acrylates of alcohols having different lengths.

[0048] The particularly preferred acrylate of formula (I) is selected from the group consisting of: n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, isononyl acrylate, isodecanyl acrylate, isothidecyl acrylate, n-decyl acrylate, lauryl acrylate or mixtures thereof.

[0049] According to the present invention, based on the total weight of the copolymer, the copolymer of the present invention comprises 0.1 to 39.9% by weight of monomeric unit b) derived from at least one nonfunctionalized α-olefin of formula (II), wherein R2 refers to a straight-chain alkyl group having 8 to 14 carbon atoms. According to one aspect of the present invention, preferably, based on the total weight of the copolymer, the copolymer comprises 4.5 to 35% by weight, preferably 4.9 to 30% by weight, more preferably 9.2 to 25% by weight of monomeric unit b) derived from at least one nonfunctionalized α-olefin of formula (II).

[0050] The most preferred nonfunctionalized α-olefin of formula (II) b) is selected from the group consisting of: decene, dodecene, tetradecene, hexadecene or mixtures thereof.

[0051] According to the present invention, based on the total weight of the copolymer, the copolymer of the present invention further comprises 0.1 to 5% by weight of monomeric units c derived from at least one hydroxyfunctional (meth)acrylate of formula (III). Preferably, based on the total weight of the copolymer, the copolymer comprises 0.5 to 5% by weight, preferably 0.8 to 5% by weight of monomeric units c derived from at least one nonfunctionalized α-olefin of formula (II).

[0052] Preferred hydroxy-functionalized (meth)acrylates of formula (III) c) are selected from the group consisting of: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, trimethylolpropane mono(meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-hydroxy-2-methylpropyl (meth)acrylate, or mixtures thereof. Most preferred hydroxy-functionalized (meth)acrylates of formula (III) c) are selected from the group consisting of: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, or mixtures thereof.

[0053] According to another aspect of the invention, the copolymer preferably has a kinematic viscosity of 100 to 1,000 mm² / s at 100°C according to ASTM D 445, more preferably a kinematic viscosity of 120 to 700 mm² / s at 100°C according to ASTM D 445, and even more preferably a kinematic viscosity of 150 to 500 mm² / s at 100°C according to ASTM D 445.

[0054] According to another preferred aspect of the invention, based on the total weight of the copolymer, the total content of monomer units derived from monomers a), b) and c) in the copolymer of the invention is 90% by weight or higher, more preferably 95% by weight or higher, even more preferably 98% by weight or higher, and most preferably 100% by weight.

[0055] According to the invention, the copolymer has a weight-average molecular weight of 5,000 to 30,000 g / mol, preferably 8,000 to 30,000 g / mol, more preferably 10,000 to 25,000 g / mol, and even more preferably 12,000 to 20,000 g / mol, according to DIN 55672-1.

[0056] According to the present invention, the weight-average molecular weight (M) of the polymer w ) and number-average molecular weight (M n According to DIN 55672-1, the following measurement conditions were used to determine the following: using polymethyl methacrylate (PMMA) calibration standards by gel permeation chromatography (GPC):

[0057] Eluent: Tetrahydrofuran (THF), which contains 0.02 M of 2-diethylaminoethylamine

[0058] Operating temperature: 35℃

[0059] Columns: The column group consists of a front column (SDV 10μ; 8 × 50 mm) and the following four columns: SDV 106 Å, SDV 105 Å and 2 SDV 103 Å (PSS Standards Service GmbH, Mainz, Germany). All four columns have a size of 300 × 8 mm and an average particle size of 10 µm.

[0060] Flow rate: 1 mL / min

[0061] Injection volume: 100 μL

[0062] Instrument: Agilent 1100 series, which consists of an autosampler, pump, and column oven.

[0063] Detection device: Refractive index detector, from Agilent 1260 series.

[0064] Preferably, the copolymers of the present invention have very low crosslinking degree and narrow molecular weight distribution, which further contributes to shear resistance. Low crosslinking degree and narrow molecular weight are reflected in the polydispersity index (PDI) of the copolymers. Preferably, the polydispersity index (PDI) of the copolymers according to the present invention is in the range of 1.0 to 5.0, more preferably in the range of 1.0 to 4.0, even more preferably in the range of 1.0 to 3.5, and most preferably in the range of 1.5 to 3.0. In terms of the shear resistance of the copolymers, a polydispersity index in the range of 1.0 to 3.5 is considered optimal for most industrial applications. The polydispersity index is defined as the ratio of weight-average molecular weight to number-average molecular weight (Mi). w / M n ).

[0065] According to a preferred aspect of the invention, the polymer of the invention has a COC flash point of 250°C or higher according to ASTM D92.

[0066] According to one aspect of the invention, the monomer composition may also contain an additional monomer d) in addition to monomers a), b), and c), provided that the properties of the hydroxyl-functionalized acrylate-olefin copolymer are not negatively affected.

[0067] According to the invention, the copolymer is a statistical copolymer in which monomer units a), b) and c) and optionally any other monomer units d) are randomly distributed in the copolymer and sometimes unevenly distributed.

[0068] Surprisingly, it has been observed that the combination of monomer unit a) of formula (I) with α-olefin monomer unit b) of formula (II) and hydroxyl-functionalized (meth)acrylate c) of formula (III) allows for the preparation of copolymers that exhibit excellent thickening properties in lubricant formulations when used as additives or base fluids. As demonstrated in the experimental section of this invention, the lubricant formulations of this invention exhibit excellent thickening properties and improve the dispersing power of lubricant formulations and / or reduce sludge deposition in lubricant formulations.

[0069] Preparation method of copolymer according to the present invention

[0070] According to the present invention, the above polymer is prepared by a method comprising the following steps:

[0071] i) Provide the monomer composition as described above;

[0072] ii) Initiate free radical polymerization in the monomer composition to obtain a copolymer.

[0073] Standard free radical polymerization is detailed, particularly in Ullmann's Encyclopedia of Industrial Chemistry, sixth edition. Typically, polymerization initiators and, optionally, chain transfer agents are used for this purpose.

[0074] The polymerization step ii) can be carried out under standard pressure, reduced pressure, or increased pressure. In the context of this invention, the term "standard pressure" means ambient pressure or atmospheric pressure, without additional pressure.

[0075] For free radical copolymerization of olefins and acrylates, the polymerization temperature is critical. Typically, the copolymerization temperature is in the range of 130 to 180°C, preferably in the range of 140 to 170°C.

[0076] The polymerization step ii) can 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.

[0077] Preferably, step ii) includes the addition of a free radical initiator. Preferably, the free radical initiator is selected from the group consisting of: di-tert-amyl peroxide, 2,2-di(tert-butylperoxy)butane, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, dicumyl peroxide, or di-tert-butyl peroxide. Preferably, the total amount of the free radical initiator is 0.01 to 5% by weight relative to the total weight of the monomer mixture, more preferably 0.1 to 1% by weight. Preferably, the total amount of the free radical initiator is added continuously during the copolymerization reaction ii).

[0078] Preferably, the copolymerization step ii) is carried out by feeding the acrylate monomers a), monomers c), and optionally any other comonomers together with an initiator into the nonfunctionalized α-olefin monomer b). Preferably, the total reaction time for free radical polymerization is 2 to 5 hours, more preferably 2 to 4 hours, and most preferably 3 hours.

[0079] In another preferred aspect of the invention, an additional step, corresponding to a distillation step, is optionally performed after step ii) to remove unreacted α-olefin monomer b). Preferably, a rotary evaporator is used to remove residual unreacted α-olefin monomer b) by distillation at a temperature of 140 to 180°C and a pressure as low as 5 mbar.

[0080] Preparation method of lubricant formulation according to the present invention

[0081] According to the present invention, the above-mentioned lubricant formulation is prepared by a method comprising the following steps:

[0082] i) Provide a monomer composition as defined above,

[0083] ii) Initiate free radical polymerization in the monomer composition of step i) to obtain a copolymer.

[0084] iii) Mix the copolymer from step ii) with the base oil.

[0085] All preferred aspects of the copolymers, copolymer preparation, base oils, and quantities listed above are applicable to lubricant formulations and their preparation according to the present invention.

[0086] Uses of the lubricant formulation of the present invention

[0087] The present invention also relates to the use of the lubricant formulation according to the invention as a lubricant formulation, which is achieved by adding the hydroxyl-functionalized acrylate-olefin copolymer as defined herein to the lubricant formulation.

[0088] The present invention also relates to a method for thickening lubricant formulations and improving their dispersibility and / or reducing sludge deposition, which is achieved by adding the hydroxyl-functionalized acrylate-olefin copolymer as defined in the present invention as a lubricant additive or a synthetic base fluid to the lubricant formulation.

[0089] Preferably, the lubricating oil composition is a gear oil composition, a transmission oil composition, a hydraulic oil composition, an engine oil composition, a marine oil composition, an industrial lubricating oil composition, or a grease. Detailed Implementation

[0090] Experimental Section

[0091] The invention is further illustrated in detail below with reference to and comparative embodiments, but is not intended to limit the scope of the invention. All percentages of monomers or base fluids given in the following table are weight percentages (wt%).

[0092] Abbreviation

[0093] Acr. acrylate

[0094] Anglamol 6043 is available in additive packets from Lubrizol.

[0095] BF-40's Brinell viscosity at -40°C, measured according to ASTM D2983.

[0096] BV Bulk Viscosity

[0097] BV100 bulk viscosity at 100°C according to ASTM D445

[0098] cSt centiliter, corresponding to mm² / s in SI units.

[0099] cP centipoise, corresponding to mPa in SI units. . s

[0100] DBPO (di-tert-butyl peroxide)

[0101] Dec 1-decene

[0102] DMAEMA (Dimethylaminoethyl methacrylate)

[0103] DMAPMAM (Dimethylaminopropylmethylacrylamide)

[0104] EHA 2-Ethylhexyl Acrylate

[0105] GMMA (2,3-dihydroxypropyl methacrylate)

[0106] HEMA 2-hydroxyethyl methacrylate

[0107] HPMA 2-Hydroxypropyl Methacrylate

[0108] IDA Isodecyl Acrylate

[0109] Ini initiator

[0110] KRL's tapered roller bearing shear stability test according to CEC L-45-A-99

[0111] KV kinematic viscosity as measured by ASTM D445

[0112] KV40 kinematic viscosity measured at 40°C according to ASTM D445.

[0113] KV100 kinematic viscosity measured at 100°C according to ASTM D445.

[0114] LA lauryl acrylate or dodecyl acrylate

[0115] M n Number average molecular weight

[0116] M w Weight-average molecular weight

[0117] nm was not measured.

[0118] PDI (Polydispersity Index)

[0119] PHA 2-propylheptyl acrylate

[0120] PPD (Pour Point Depressant)

[0121] Shear loss of SL measured at 100°C after running at KRL (for 20 hours at 60°C)

[0122] TAN based on the total acid value according to ASTM D664

[0123] TBN Total Base Number according to ASTM D2896

[0124] TR dosage (polymer content in the formulation, expressed as a percentage by weight)

[0125] VI Viscosity Index

[0126] VPL 1-300 Evonik VISCOPLEX ® 1-300, Pour Point Depressant for Alkyl Polymethacrylate

[0127] The content of monomer c) by weight (%) is the percentage of monomer c) based on the total weight of the copolymer.

[0128] Yubase 4 is a Group III base oil from SK Lubricants with KV100 and a flow rate of 4 mm² / s.

[0129] Yubase 6 is a Group III base oil from SK Lubricants with KV100 and a flow rate of 6 mm² / s.

[0130] Yubase 8 is a Group III base oil from SK Lubricants with KV100 and a flow rate of 8 mm² / s.

[0131] Test methods

[0132] KV ASTM D445

[0133] VI ASTM D2270

[0134] KRL CEC L-45-A-99

[0135] BF ASTM D2983

[0136] TAN ASTM D664

[0137] TBN ASTM D2896

[0138] In this invention, the bulk viscosity (BV) of the polymer (the product obtained from the polymerization reaction) corresponds to the kinematic viscosity (KV) of the resulting polymer product as measured according to ASTM D445. Therefore, the bulk viscosity (BV100) of the polymer shown in Table 1 below is measured as the kinematic viscosity at 100°C according to ASTM D445.

[0139] The oxidation performance of the embodiments and comparative embodiments of the present invention was evaluated using an oxidation test (CEC SG-L-048 Oxidation Stability of Lubricating Oils used in Automotive Transmissions by Artificial Ageing). The performance of the lubricating oil composition in the oxidation test according to CEC SG-L-48 is an important standard for automotive gear oils. Part of this test includes visual inspection of residues in a glass tube and chromatographic testing, both of which indicate the extent to which the lubricant can prevent the deposition of insoluble oxidation products. This method was carried out at 160°C for 192 hours. Before the oxidation test (freshly prepared oil), the kinematic viscosity and acid value (TAN, ASTM D 664) of the freshly prepared formulation were measured at 40°C and 100°C and compared with the corresponding values ​​after oxidation (oxidized oil). The difference in KV100 value and the difference in TAN value between the freshly prepared oil and the oxidized oil are referred to as "ΔKV100" and "ΔTAN," respectively. Furthermore, the dispersing power performance was evaluated by performing a spot test, in which a single drop of the formulation was dropped onto a sheet of blotting paper after oxidation (80°C) and the spot size was assessed. A higher spot area on the blotting paper corresponds to a better dispersant.

[0140] Example

[0141] Synthesis procedure of copolymer of the present invention in Example 1

[0142] 2.72 g of DBPO (0.5 wt% relative to the monomers in the feed), dissolved in 521.25 g of EHA and 22.5 g of HEMA (3 wt% relative to all monomers), was slowly fed into 206.25 g of 1-decene (27.5 wt% relative to all monomers) at 150°C under nitrogen for 3 hours. After stirring for another 1.2 hours, the resulting clarified polymer was cooled. Residual decene was then removed by distillation using a rotary evaporator at 160°C and pressures as low as 5 mbar. The amount of decene incorporated into the polymer was determined by gravimetric analysis, assuming the absence of residual (meth)acrylate monomers.

[0143] Except for changes in the amounts of reactants and other reaction conditions as listed in Table 1, all examples were prepared in the same manner as Example 1 of the present invention. For Examples 2 to 6, 8 and 9, a stabilizer (4-methyl-2,6-di-tert-butylphenol) was added in an amount of 0.2% by weight relative to the reaction mixture prior to the distillation step.

[0144] Further details of the synthesis procedures for each embodiment, along with the basic properties of the polymers, are provided in Table 1. The α-olefin monomer is always the first to be charged into the reactor. Subsequently, the acrylate and dispersant monomers, along with the initiator, are fed over a set time period. For acrylate-olefin copolymers containing acrylate (mixture) and dispersant monomers, they are all mixed with the initiator before being fed into the olefin. For all embodiments, DBPO at 0.5% by weight relative to the monomers in the feed is used as the initiator. The temperatures given in Table 1 correspond to the reaction temperatures during the feeding period.

[0145] It was observed that all polymer examples 1 to 12 of the present invention were colorless, in contrast to the pale yellow N-dispersant polymer example 15. Up to Example 16 This represents a further advantage sought in industry.

[0146] In addition, the total base number (TBN) was evaluated according to ASTM D2896. The TBN of the polymers of the present invention in Examples 7 to 12 was consistently below 0.15, while that in Comparative Example 15, which contained DMAEMA, was significantly lower. It exhibits a significantly higher TBN of 15.6. The lower TBN of the thickener provides greater flexibility in lubricant formulations and is beneficial for long-term performance, as the impact of acidic oxidation products on dispersing properties is expected to be less.

[0147] Formulations comprising the polymers of the present invention and comparative polymers listed in Table 1 were prepared. The proportions of the different components are provided in Tables 2 through 4. Along with the results from the oxidation tests, the performance of the different formulations using the embodiments of the present invention is shown, including, for example, viscosity index, kinematic viscosity, Brookfield viscosity, and shear loss.

[0148] Tables 2 to 4 also list the content of hydroxyl functional monomer (c) in the formulations (OH-functional monomer c) content, which corresponds to the weight content (wt%) of monomer c) in the polymer multiplied by the dosage (TR). For example, formulation example F-1 contains 30.2 wt% of polymer example 1, which has 3.2 wt% HEMA. Therefore, the weight % of monomer c) is 3.2 and the TR is 30.2, resulting in a content of OH-functional monomer c) in the formulation of 3.2 × 30.2 = 97. As shown in Tables 2 and 3, all formulations of the present invention according to the present invention have a content of less than 100 of OH-functional monomer c) in the formulation.

[0149] The objective was to obtain formulations that met the SAE 75W-90 (Table 2) or 75W-80 (Table 3) standards (SAE is the Society of Automotive Engineers). Table 4 provides comparative examples of 75W-90 and 75W-80 formulations and their oxidation performance.

[0150] Table 1 Polymer properties of the prepared acrylate-olefin copolymer

[0151]

[0152] The amount of olefin monomers added to the reaction vessel (olefin input) and the amount of olefin monomers incorporated into the final polymer (olefin incorporation), expressed as a percentage by weight.

[0153] Table 2 75W-90 formulation of acrylate-olefin copolymer according to the present invention

[0154]

[0155] Table 3 75W-80 formulation of acrylate-olefin copolymer according to the present invention

[0156]

[0157] Table 4 Comparative Examples of 75W-90 and 75W-80 Formulations of Acrylate-Olefin Copolymers

[0158]

[0159] Comparative Example 13 of this patent application Example 5, similar to EP401604, contains EHA and 1-decene. These EHA-containing copolymers (which are quite polar due to their short side chains) showed poor performance in the dispersibility rating according to the oxidation test of CEC SG-L-48, as shown in Formulation Example F-1 in Table 4. As shown in Table 2 above, the lubricant formulations containing the hydroxy-functionalized acrylate-olefin copolymer according to the invention achieve better performance in sludge treatment. In fact, as shown in Table 3 above, the 75W-90 formulations (F-1 to F-10) containing the hydroxy-functionalized acrylate-olefin copolymer according to the invention exhibit good oxidation performance in oxidation tests, achieving a 100% dispersing power rating in the spot test (blotting paper spot area). Even at lower dosages, such as in the 75W-80 formulations shown in Table 3 (F-11 to F-17), the dispersing power surprisingly remains above 60%.

[0160] In addition, comparative formulation example F-2 and F-3 It was confirmed that the high number of OH- functional groups in the formulation led to a high viscosity increase in the oxidation test. In these cases, it is not even possible to clearly determine the increase in KV100 between freshly prepared and oxidized oils; only the range of increase can be given. For formulation F-2... and F-3 Both showed an increase in KV100 exceeding 130 mm² / s. (For F-2) Comparative Examples, Example 14 The polymer composition contains >5% by weight of the OH-functional monomer HEMA. Used in F-3 Polymer Example 12 contained 4.9 wt% HEMA, and therefore the concentration of the OH-functional monomer in the final formulation was also higher than the concentration allowed by the limitation of [weight% of monomer c] × TR < 100. However, the same polymer (Example 12) used in the 75W-80 formulation (F-7), which required only a 4.9 wt% polymer dosage, showed good oxidizing properties. Here, the limitation of [weight% of monomer c] × TR < 100 was satisfied.

[0161] Regarding dispersing power, the hydroxyl-functionalized polymers exhibited levels typical of nitrogen-containing polymers, which was quite unexpected, as nitrogen functionality is more typical in dispersants (US20150274875, US10428292). Even more surprisingly, the formulations containing hydroxyl-functionalized monomers showed lower acid values ​​after oxidation, and particularly a smaller increase in acid value. It was expected that the basic nitrogen functionality would perform better in both tests. Polymers containing N-dispersant functional groups (e.g., Comparative Example 15) and Example 16 This higher acid value increase was observed after oxidation testing. These comparative examples in the 75W-90 formulation showed 2.6 mg KOH / g (F-5) Up to 6.4 mg KOH / g (F-4) The acid value (ΔTAN) increases, while in the 75W-90 formulation, the increase in the embodiments of the present invention is 2.0 mg KOH / g or less (F-1 to F-10).

[0162] Compared to similar polymers containing N-functional dispersant monomers, the polymers of the present invention containing hydroxyl-functional dispersant monomers exhibit superior oxidation properties, along with good dispersibility and a low increase in acid value due to oxidation. Polymers with higher contents of hydroxyl-functional monomers, or formulations containing high amounts of hydroxyl-functional monomers due to high dosage, exhibit a significant increase in kinematic viscosity at 100°C after oxidation, in addition to the claimed compositions. Therefore, the type and amount of dispersant monomers are crucial for the oxidation properties of said polymers, and consequently for the oxidation properties of their lubricant formulations.

Claims

1. A lubricant formulation comprising a base oil and a hydroxyl-functionalized acrylate-olefin copolymer. The copolymer described herein has a weight-average molecular weight of 5,000 to 30,000 g / mol according to DIN 55672-1 and comprises: a) Based on the total weight of the copolymer, 60 to 99.8% by weight of monomer units derived from at least one acrylate of formula (I), (I) R1 refers to a straight-chain or branched alkyl group having 8 to 15 carbon atoms. b) Based on the total weight of the copolymer, 0.1 to 39.9% by weight of monomer units derived from at least one nonfunctionalized α-olefin of formula (II), (II) R2 refers to a straight-chain alkyl group having 8 to 14 carbon atoms, and c) Based on the total weight of the copolymer, 0.1 to 5% by weight of monomer units derived from at least one hydroxyl-functional (meth)acrylate monomer c), and The lubricant formulation has a content of less than 100% of the hydroxyl-functional (meth)acrylate monomer c) in the formulation, calculated according to formula (III): [weight% of monomer c)] × TR < 100 (III) Wherein [weight% of monomer c)] is the total weight content of monomer c) in the polymer, and where TR is the polymer dosage in the lubricant formulation by weight percentage.

2. The lubricant formulation according to claim 1, wherein, based on the total weight of the copolymer, the copolymer comprises 65.5 to 95% by weight, preferably 74.2 to 90% by weight, of monomeric units a derived from at least one acrylate of formula (I).

3. The lubricant formulation according to claim 1 or 2, wherein, based on the total weight of the copolymer, the copolymer comprises 4.5 to 35% by weight, preferably 4.9 to 30% by weight, more preferably 9.2 to 25% by weight, of monomeric units b derived from at least one nonfunctionalized α-olefin of formula (II).

4. The lubricant formulation according to any one of the preceding claims, wherein, based on the total weight of the copolymer, the copolymer comprises 0.5 to 5% by weight, preferably 0.8 to 5% by weight, of monomeric units derived from at least one hydroxy-functional (meth)acrylate.

5. The lubricant formulation according to any one of the preceding claims, wherein the copolymer has a kinematic viscosity of 100 to 1,000 mm² / s at 100°C according to ASTM D445, preferably 120 to 700 mm² / s at 100°C according to ASTM D445, and more preferably 150 to 500 mm² / s at 100°C according to ASTM D445.

6. The lubricant formulation according to any one of the preceding claims, wherein the acrylate of formula (I) a) is selected from the group consisting of: n-octyl acrylate, 2-ethylhexyl acrylate, 2-propylheptyl acrylate, isononyl acrylate, isodecanyl acrylate, isothidecyl acrylate, isothidecyl acrylate, n-decyl acrylate, lauryl acrylate or mixtures thereof.

7. The lubricant formulation according to any one of the preceding claims, wherein the nonfunctionalized α-olefin (b) of formula (II) is selected from the group consisting of decene, dodecene, tetradecene, hexadecene, or mixtures thereof.

8. The lubricant formulation according to any one of the preceding claims, wherein the hydroxy-functional (meth)acrylate c) is selected from the group consisting of: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, trimethylolpropane mono(meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-hydroxy-2-methylpropyl (meth)acrylate, or mixtures thereof.

9. The lubricant formulation according to any one of the preceding claims, wherein, based on the total weight of the copolymer, the total amount of monomer units derived from monomers a), b) and c) in the copolymer is 90% by weight or higher, preferably 95% by weight or higher, and more preferably 98% by weight or higher.

10. The lubricant formulation according to any one of the preceding claims, wherein the copolymer has a weight-average molecular weight of 8,000 to 30,000 g / mol, preferably 10,000 to 25,000 g / mol, and even more preferably 12,000 to 20,000 g / mol, according to DIN 55672-1.

11. The lubricant formulation according to any one of the preceding claims, wherein the copolymer has a polydispersity index of 1.0 to 3.5, preferably 1.5 to 3.

0.

12. The lubricant formulation according to any one of the preceding claims, wherein, based on the total weight of the lubricant formulation, the lubricant formulation comprises 0.1 to 99.9% by weight, more preferably 3 to 99% by weight, of the copolymer.

13. A method for preparing a lubricant formulation according to any one of claims 1 to 12, wherein the method comprises the following steps: i) Provides a monomer composition according to any one of claims 1 to 4 and 6 to 9, ii) Initiate free radical polymerization in the monomer composition of step i) to obtain the copolymer according to any one of claims 1 to 11. iii) Mix the copolymer from step ii) with the base oil.

14. The use of the formulation as a lubricant formulation according to any one of claims 1 to 12, preferably as a gear oil lubricating composition, transmission oil lubricating composition, hydraulic oil lubricating composition, engine oil lubricating composition, marine oil lubricating composition, industrial lubricating oil composition or grease, which is achieved by adding the copolymer as defined in any one of claims 1 to 12 to the lubricant formulation.

15. A method for thickening a lubricant formulation and improving its dispersibility and / or reducing sludge deposition, wherein the method comprises adding the copolymer as defined in any one of claims 1 to 12 as a lubricant additive or a synthetic base fluid to the lubricant formulation.

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