Lubricating oil viscosity index improver additives and methods for their preparation

Abstract

A lubricating oil viscosity index improver (VII) additive containing hydrogenated linear polybutadiene, wherein the hydrogenated linear polybutadiene has the following characteristics: - weight-average molecular weight (M w - The molecular weight is from 1,000 Daltons to 40,000 Daltons, preferably from 1,500 Daltons to 38,000 Daltons; - The content of units having configuration 1,2 is 40% to 80% by weight, preferably 45% to 75% by weight, relative to the total amount of butadiene units present in the hydrogenated linear polybutadiene; - Polydispersity index (PDI), i.e., weight-average molecular weight (M w ) and number-average molecular weight (M n The ratio of (M) w / M n The following properties are considered: - 1.3 or less, preferably 1 to 1.1; - Degree of hydrogenation greater than or equal to 98%, preferably 98.5% to 100%; - Dynamic viscosity measured at 40°C of 5 Pa*s to 10000 Pa*s, preferably 10 Pa*s to 8000 Pa*s; - Dynamic viscosity measured at 100°C of 0.1 Pa*s to 1000 Pa*s, preferably 0.2 Pa*s to 500 Pa*s; - Enthalpy of crystallization (ΔHc) determined by temperature-modulated differential scanning calorimetry (TMDSC) of 0 J / g to 1 J / g, preferably 0 J / g to 0.8 J / g. The aforementioned lubricant improver (VII) additive can be advantageously used in lubricant compositions, for example, for lubricant compositions for diesel and gasoline passenger cars or heavy-duty diesel engines, for functional fluids, for example, fluids for manual or automatic transmissions, hydraulic fluids, and for industrial lubricants (e.g., gear lubricants for wind turbines).

Description

[0001] This invention relates to lubricating oil viscosity index improver (VII) additive.

[0002] More specifically, the present invention relates to a lubricating oil viscosity index improver (VII) additive comprising hydrogenated linear polybutadiene having the specific characteristics described below.

[0003] The aforementioned lubricating oil viscosity index improver (VII) additive can be advantageously used in lubricating oil compositions (e.g., lubricating oil compositions for diesel buses and gasoline buses or heavy-duty diesel engines), functional fluids (e.g., fluids for manual or automatic transmissions, hydraulic fluids), and industrial lubricants (e.g., gear lubricants for wind turbines).

[0004] The present invention also relates to a method for preparing the hydrogenated linear polybutadiene.

[0005] The present invention also relates to a concentrated solution comprising at least one of the above-mentioned lubricating oil viscosity index improver (VII) additives in at least one lubricating base oil, said lubricating base oil being selected from mineral-derived, synthetic-derived lubricating base oils or mixtures thereof.

[0006] The present invention also relates to a lubricating oil composition comprising at least one of the above-mentioned lubricating oil viscosity index improver (VII) additives (in its own form or in concentrated solution form) and at least one lubricating base oil selected from mineral-derived, synthetic-derived lubricating base oils or mixtures thereof.

[0007] It is well known that the viscosity of lubricating oil changes with temperature. Many lubricating oils actually need to be used over a wide temperature range, so it is important that the oil is not too viscous at low temperatures and not too fluid at high temperatures. The change in lubricating oil viscosity with temperature is represented by the viscosity index value: the higher the viscosity index value, the smaller the change in lubricating oil viscosity with temperature.

[0008] The use of polymer-based additives as lubricant viscosity index improvers (VII) is also known to adjust the viscosity of the lubricant as temperature changes, i.e., increasing viscosity at high temperatures and limiting viscosity increase at low temperatures as much as possible.

[0009] For example, polymers commonly used as lubricant viscosity index improvers (VII) are: ethylene-propylene copolymers [also known in the art as olefin copolymers (OCP)], hydrogenated conjugated polydienes (e.g., hydrogenated polyisoprene), hydrogenated styrene / butadiene copolymers, hydrogenated styrene / isoprene copolymers, polyalkyl methacrylates, and diene / alkyl methacrylate copolymers.

[0010] For example, the synthesis of hydrogenated linear polymers of conjugated dienes and styrene-conjugated diene copolymers in lubricant compositions and their use in lubricants are described in the following patents, such as: US 3,554,911 (hydrogenated butadiene-styrene random copolymer); US 3,668,125 (hydrogenated or saturated block copolymers having at least three blocks, e.g., polystyrene-hydrogenated polybutadiene-polystyrene, polystyrene-hydrogenated polyisoprene-polystyrene); US 3,772,196 [diblock copolymers comprising a first block derived from an alkenyl aromatic hydrocarbon (e.g., styrene) and a second block derived from substantially fully hydrogenated isoprene]; US 3,775,329 (“conical” hydrogenated isoprene-styrene copolymer); US 3,835,053 (hydrogenated polyisoprene homopolymer); EP 585269 [hydrogenated butadiene-diene copolymers, such as hydrogenated butadiene-isoprene copolymers, which may have a star-shaped structure] and EP 578725 (hydrogenated polybutadiene block copolymers comprising 1,4-butadiene monomer units and 1,2-butadiene monomer units).

[0011] For example, the synthesis of ethylene-propylene copolymers and lubricating compositions containing them are described in patents EP 3,950,897, EP 3,950,892, EP 3,950,899, EP 3,950,898, EP 3,950,902, EP 3,950,900, EP 3,950,895, EP 3,950,893, EP 3,950,901 and EP 3,950,894.

[0012] Furthermore, since low molecular weight is essential for ensuring the performance of the lubricating oil viscosity index improver (VII), and the methods commonly used to produce ethylene copolymers and terpolymers [EP(D)M] (solution or slurry methods) typically provide ethylene copolymers and terpolymers [EP(D)M] with significantly higher molecular weights, it is necessary to subject the ethylene copolymers and terpolymers [EP(D)M] to a thermal degradation process, as described, for example, in patents EP 1,013,673 and US 6,753,381.

[0013] For example, patent CN 113461881 describes the in-situ synthesis of hydrogenated styrene-diene copolymers with star-shaped structures in low-viscosity base oils and lubricating oil compositions containing them.

[0014] For example, patents EP 3,880,774 and EP 3,498,808 describe the synthesis of diene-alkyl methacrylate copolymers in conventional solvents (e.g., toluene, 1-decene, cyclohexane).

[0015] For example, EP 3,510,131 describes a lubricating oil composition containing low molecular weight polymethacrylate.

[0016] For each of the aforementioned copolymers, an increase in weight-average molecular weight (Mw) corresponds to an increase in thickening capacity (TP), thus reducing the amount of copolymer required to achieve a certain increase (thickening) in the viscosity index of the high-temperature lubricating oil composition. For a copolymer to be a good viscosity index improver (VII) additive, it must not only have a beneficial effect on the viscosity index of fresh lubricating oil, but it must also be stable enough to maintain its function even when the lubricating oil is used in an engine. Therefore, a good viscosity index improver (VII) additive must also have good mechanical shear stability [i.e., a good shear stability index (SSI) value]. As is well known, in contrast to thickening capacity (TP), the mechanical shear stability of (co)polymers decreases with increasing weight-average molecular weight (Mw). Therefore, the selection of viscosity index improver (VII) additives is often a compromise between using a large amount of low weight-average molecular weight (Mw) (co)polymers that are mechanically shear stable [i.e., have low shear stability index (SSI) values] but have low thickening capacity (TP) and using a small amount of high weight-average molecular weight (Mw) (co)polymers that are poorly mechanically shear stable [i.e. have high shear stability index (SSI) values] but have high thickening capacity (TP).

[0017] However, the above methods can have some drawbacks. For example, to obtain ethylene-propylene copolymers with molecular weights suitable for use as viscosity index improvers (VII), it may be necessary to use hydroperoxides or operate at high temperatures (up to 500°C), which requires operation in an inert atmosphere (e.g., in the presence of nitrogen), and this can lead to gelation and branching in the final product. Furthermore, to improve the dimensional stability of the obtained ethylene-propylene copolymers, it may be necessary to use small amounts of polyvinyl aromatics / hydrogenated conjugated diene / polyvinyl aromatics block copolymers or multifunctional vinyl monomers.

[0018] Furthermore, the polydispersity index of ethylene-propylene copolymers obtained by Ziegler-Natta polymerization is typically greater than 2, which means that in order to maximize mechanical shear stability, it is necessary to synthesize ethylene-propylene copolymers with extremely low weight-average molecular weight (Mw) at the expense of viscosity index.

[0019] Therefore, the applicant has raised the issue of finding a lubricating oil viscosity index improver (VII) additive that can exhibit excellent shear stability index (SSI) value and good low-temperature fluidity (“pour point”).

[0020] The applicant has now discovered a lubricating oil viscosity index improver (VII) additive comprising hydrogenated linear polybutadiene having the following specific characteristics. The aforementioned lubricating oil viscosity index improver (VII) additive is advantageously applicable to lubricating oil compositions (e.g., lubricating oil compositions for diesel and gasoline passenger cars or heavy-duty diesel engines), functional fluids (e.g., fluids for manual or automatic transmissions, hydraulic fluids), and industrial lubricants (e.g., gear lubricants for wind turbines). Therefore, the aforementioned lubricating oil viscosity index improver (VII) additive is particularly useful in the engine field, where proper lubrication is increasingly important for extending engine life (especially diesel engines, and the latest direct-injection gasoline engines) and reducing fuel consumption; thus, proper lubrication has a direct benefit to sustainability and reduction in engine emissions. Furthermore, the aforementioned lubricating oil viscosity index improver (VII) additive is particularly useful in fields requiring excellent mechanical shear stability [i.e., a good shear stability index (SSI) value] and good low-temperature performance [i.e., good low-temperature flowability (“pour point”)].

[0021] Therefore, the object of the present invention is a lubricating oil viscosity index improver (VII) additive comprising hydrogenated linear polybutadiene, wherein the hydrogenated linear polybutadiene has the following characteristics:

[0022] - Weight-average molecular weight (M w The range is from 1,000 Daltons to 40,000 Daltons, preferably from 1,500 Daltons to 38,000 Daltons;

[0023] - The content of units having configuration 1,2 is 40% to 80% by weight, preferably 45% to 75% by weight, relative to the total amount of butadiene units present in the hydrogenated linear polybutadiene;

[0024] - Polydispersity Index (PDI), i.e., weight-average molecular weight (M). w ) and number-average molecular weight (M n The ratio of (M) w / M n The value is less than or equal to 1.3, preferably 1 to 1.1;

[0025] - The degree of hydrogenation is greater than or equal to 98%, preferably 98.5% to 100%;

[0026] - The dynamic viscosity measured at 40°C is from 5 Pa*s to 10000 Pa*s, preferably from 10 Pa*s to 8000 Pa*s;

[0027] - The dynamic viscosity measured at 100°C is from 0.1 Pa*s to 1000 Pa*s, preferably from 0.2 Pa*s to 500 Pa*s;

[0028] - The enthalpy of crystallization (ΔHc) determined by temperature-modulated differential scanning calorimetry (TMDSC) is 0 J / g to 1 J / g, preferably 0 J / g to 0.8 J / g.

[0029] For the purposes of this specification and the foregoing claims, the definition of a numerical range always includes extreme values, unless otherwise stated.

[0030] For the purposes of this specification and the foregoing claims, the term "comprising" also includes the terms "consistently composed of" or "composed of".

[0031] For the purposes of this specification and the foregoing claims, the content of the 1,2 configuration units of polybutadiene (expressed as a percentage by weight relative to the total amount of butadiene units present in hydrogenated linear polybutadiene) is as follows: “Spectrum” 1 The method reported in "H-NMR" was used to determine non-hydrogenated polybutadiene ("parent polymer").

[0032] According to a preferred embodiment of the present invention, the lubricating oil viscosity index improver (VII) additive has the following characteristics:

[0033] - The shear stability index (SSI) is 0% to 7%, preferably 0% to 5%, and is measured in Group III 4 cSt base oils according to CEC-L-14-A-93 standard (30 shear cycles);

[0034] - Pour point below -30°C, preferably -33°C to -45°C, with the addition of Viscoplex ® Measurements were performed in Group III 4 cSt base oils in the presence of V1-254 (Evonik) (pour point reducer - PPD) according to ASTM D5950-14.

[0035] According to a preferred embodiment of the invention, in order to achieve a target dynamic viscosity (6 cSt to 9 cSt, preferably 7 cSt to 8 cSt) measured in a Group III 4 cSt base oil according to ASTM D7042-04 at 100°C, the lubricating oil viscosity index improver (VII) is applied to the Group III 4 cSt base oil at a target concentration of 1.9 wt% to 12 wt%, preferably 2.1 wt% to 10 wt%, relative to the total weight of the Group III 4 cSt base oil and the viscosity index improver (VII) in the lubricating oil composition.

[0036] As described above, the present invention also relates to a method for preparing the aforementioned hydrogenated linear polybutadiene.

[0037] Therefore, another object of the present invention is a first discontinuous (intermittent) method for preparing hydrogenated linear polybutadiene, comprising the following steps:

[0038] (a) 1,3-Butadiene is subjected to living polymerization via an anionic pathway in the presence of at least one hydrocarbon solvent, at least one lithium-based initiator and at least one polar modifier, and the polymerization is continued until the 1,3-butadiene is substantially completely converted.

[0039] (b) Add at least one terminating agent to the polymerization mixture obtained in step (a);

[0040] (c) Hydrogenate the linear polybutadiene obtained in step (b) to obtain a mixture containing hydrogenated linear polybutadiene;

[0041] (d) The mixture containing hydrogenated linear polybutadiene obtained in step (c) is subjected to desolventizing treatment, and the hydrogenated linear polybutadiene is recovered;

[0042] The desolventizing step (d) is carried out in the absence of water.

[0043] For the purposes of this specification and the foregoing claims, the phrase “substantially complete conversion” means that polymerization continues until at least 98%, preferably at least 99%, more preferably 100% of the supported monomer (i.e., 1,3-butadiene) has completed polymerization.

[0044] According to a preferred embodiment of the invention, the at least one hydrocarbon solvent may be selected from, for example, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, or aromatic hydrocarbon solvents, such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, n-heptane, n-octane, cyclohexane, cyclopentane, propylene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, or mixtures thereof. The solvent may advantageously be used in anhydrous form. Anhydrous forms of cyclohexane, n-hexane, or mixtures thereof are preferred.

[0045] Typically, the amount of hydrocarbon solvent used in the copolymerization via the anionic pathway allows for complete dissolution of the monomer (i.e., 1,3-butadiene), optional additives, the compounds obtained in steps (a)-(d) above, complete stirring of the reaction mixture during the copolymerization process, and diffusion of the heat of reaction. Preferably, the hydrocarbon solvent is used in an amount such that the monomer concentration (i.e., 1,3-butadiene) in the hydrocarbon solvent is 4% to 20% by weight, more preferably 6% to 15% by weight, relative to the total weight of the hydrocarbon solvent.

[0046] According to a preferred embodiment of the present invention, the at least one lithium-based initiator may be selected, for example, from compounds having the general formula (I):

[0047] R1(Li) n (I)

[0048] Where R1 represents a straight-chain or branched alkyl group C1-C. 20 (C2-C preferred) 12 ), cycloalkyl C3-C 30 (Preferred C4-C) 10 ), aryl C6-C 30 (Preferred C6-C) 12 ), and n is an integer from 1 to 4.

[0049] According to a particularly preferred embodiment of the invention, the at least one lithium-based initiator may be selected from, for example: methyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, n-propyllithium, isobutyllithium, pentyllithium, cyclohexyllithium, phenyllithium, 1-methylstyryllithium, p-tolyllithium, naphthyllithium, L,L-diphenyl-5-lithium-3-methyl-pentyl, or mixtures thereof. n-Butyllithium is preferred.

[0050] The amount of lithium-based initiator that can be used for the purposes of the methods of the present invention depends on a variety of factors, such as the molecular weight of the polymer to be obtained and, optionally, impurities present in the polymerization mixture. Typically, the lithium-based initiator can be used in amounts from 0.16 phm to 6.4 phm, preferably from 0.17 phm to 4.3 phm (phm = parts per 100 parts by weight of monomer).

[0051] According to a preferred embodiment of the invention, the at least one polar modifier may be selected from, for example: acyclic ethers (e.g., diethyl ether) or mixtures thereof; tertiary amines, for example, tributylamine; cyclic ethers, for example, tetrahydrofuran (THF); chelating ethers, for example, ethylene glycol dimethyl ether (dimethylglyme), dioxane, 2-methoxyethyl tetrahydrofuran (THFA-ethyl), 2-methoxyethyl tetrahydropyran or mixtures thereof; chelating amines, for example, N,N,N',N'-tetramethylenediamine (TMEDA); or mixtures thereof. Tetrahydrofuran (THF), 2-methoxy-ethyl-tetrahydrofuran (THFA-ethyl), or mixtures thereof are preferred.

[0052] The amount of polar modifier that can be used for the first method objective of the present invention depends on a variety of factors, such as the type of polar modifier used and the type of lithium-based initiator used. For example, in the case of the aforementioned first method for the objective of the present invention, tetrahydrofuran (THF) can be used in an amount of 10,000 ppm to 35,000 ppm, preferably 11,000 ppm to 30,000 ppm (ppm = parts per million) relative to the hydrocarbon solvent used.

[0053] According to a preferred embodiment of the invention, the at least one terminator may be selected from, for example, trimethylchlorosilane, butanol, octanol, or mixtures thereof. Trimethylchlorosilane is preferred. Preferably, the terminator and the lithium-based initiator may be used in a molar ratio of 0.8 to 1.3, more preferably 0.9 to 1.2.

[0054] According to a preferred embodiment of the present invention, in the first method:

[0055] - Step (a) can be performed at a temperature of 20°C to 100°C, preferably 25°C to 85°C; and / or for a time of 10 minutes to 1 hour, preferably 15 minutes to 40 minutes; and / or

[0056] - Step (b) can be performed at a temperature of 30°C to 115°C, preferably 40°C to 110°C; and / or for a time of 1 minute to 30 minutes, preferably 3 minutes to 20 minutes.

[0057] The aforementioned hydrogenation step (c) can be carried out according to methods known in the art. Preferably, it can be carried out in the presence of a titanium / magnesium-based catalyst composition (e.g., bis(cyclopentadienyl)titanium dichloride / butylethylmagnesium), as described, for example, in European patents EP 0816382 and EP 0914867.

[0058] The aforementioned desolventization step (d) under water-free conditions can be carried out, for example, by vacuum evaporation or by means of a stirred thin-film evaporator.

[0059] The hydrogenated linear polybutadiene obtained at the end of the aforementioned process can be stored as is, or dissolved in mineral- or synthetic-derived oil before storage.

[0060] Another object of the present invention is a second discontinuous (intermittent) method for preparing hydrogenated linear polybutadiene via an anionic route, comprising the following steps:

[0061] (a') 1,3-Butadiene is subjected to living polymerization via an anionic pathway in the presence of at least one lubricating base oil, at least one lithium-based initiator and at least one polar modifier, and the polymerization is continued until the 1,3-butadiene is substantially completely converted.

[0062] (b') Add at least one terminating agent to the polymerization mixture obtained in step (a');

[0063] (c') Hydrogenate the linear polybutadiene obtained in step (b') to obtain a mixture containing hydrogenated linear polybutadiene;

[0064] The mixture obtained at the end of step (c') may contain 1% to 70% by weight, preferably 1.5% to 50% by weight, of hydrogenated linear polybutadiene relative to the total weight of the mixture. The mixture may be stored as is.

[0065] According to a preferred embodiment of the present invention, in the second method:

[0066] - Step (a') can be performed at a temperature of 20°C to 100°C, preferably 25°C to 85°C; and / or for a time of 10 minutes to 1 hour, preferably 20 minutes to 40 minutes; and / or

[0067] - Step (b') can be performed at a temperature of 30°C to 115°C, preferably 40°C to 110°C; and / or for a time of 1 minute to 30 minutes, preferably 3 minutes to 20 minutes.

[0068] The aforementioned hydrogenation step (c') can be carried out as described above according to methods known in the art. Preferably, it can be carried out in the presence of a titanium / magnesium-based catalyst composition (e.g., bis(cyclopentadienyl)titanium dichloride / butylethylmagnesium), as described, for example, in European patents EP 0816382 and EP 0914867.

[0069] It should be noted that, according to the second method, the desolventizing step is eliminated, thereby saving time and cost.

[0070] The at least one lithium-based initiator, at least one polar modifier, and at least one terminator may be selected from those reported above.

[0071] The at least one lubricating base oil may be selected from the mineral-derived or synthetic-derived lubricating base oils reported below.

[0072] As described above, the present invention also relates to a concentrated solution of at least one lubricating oil viscosity index improver (VII) additive containing hydrogenated linear polybutadiene in at least one lubricating base oil, said lubricating base oil being selected from mineral-derived, synthetic-derived lubricating base oils or mixtures thereof.

[0073] Mineral-derived lubricating base oils are derived from well-known refining processes such as distillation, deparaffinization, deasphalting, dearomatization, and hydrogenation.

[0074] The synthetically sourced lubricating base oil may preferably be selected from: hydrocarbon oils, such as polymerized and hydrogenated terminal or internal olefins; alkylbenzenes; polyphenylene.

[0075] Another method of classifying lubricating base oils is the one defined by the American Petroleum Institute (API) in its publication "Engine Oil Licensing and Certification System" (API EOLCS, 1507 - Industrial Services Department, 14th Edition, December 1996, Appendix 1, December 1998).

[0076] According to the aforementioned classification method (API), lubricating base oils are subdivided into five categories based on their chemical-physical properties and compositional characteristics.

[0077] According to the aforementioned classification method (API), the lubricating base oils that can be used according to the present invention belong to all Group I, II, III, IV and V, and more preferably those belonging to Group III and IV.

[0078] As described above, the present invention also relates to a lubricating oil composition comprising at least one lubricating oil viscosity index improver (VII) additive containing hydrogenated linear polybutadiene (in its own form or in concentrated solution form) and at least one lubricating base oil selected from mineral-derived, synthetic-derived lubricating base oils or mixtures thereof.

[0079] Therefore, the present invention also relates to a lubricating oil composition comprising at least one lubricating base oil and at least one lubricating oil viscosity index improver (VII) additive comprising hydrogenated linear polybutadiene, wherein the lubricating base oil is selected from mineral-derived, synthetic-derived lubricating base oils or mixtures thereof, and the additive is present in the lubricating oil composition in an amount of 0.5% to 50% by weight, preferably 1% to 35% by weight, relative to the total weight of the lubricating oil composition.

[0080] In addition to the lubricating oil viscosity index improver (VII) additive containing hydrogenated linear polybutadiene, the aforementioned lubricating oil composition may also contain other additives capable of improving viscosity index, detergent additives, dispersant additives, antioxidant additives, friction modifier additives, wear-resistant and extreme pressure additives (EP additives), corrosion inhibitors, pour point depressant additives, foam inhibitors, emulsifiers, or mixtures thereof.

[0081] To better understand and put the invention into practice, some illustrative and non-limiting embodiments of the invention are reported below.

[0082] Use the analytical and characterization methods reported below.

[0083] In the case of obtaining hydrogenated linear polybutadiene according to the aforementioned second method (i.e., in the presence of at least one lubricating base oil), it is necessary to separate them from the oil before proceeding with the analysis reported below.

[0084] To this end, 500 ml of ethanol (Merck) and a magnetic anchor were added to a 1-liter beaker, followed by 25 ml of the hydrogenated linear oil / polybutadiene mixture obtained as described in the following examples: the solution was kept at room temperature (25°C) with stirring for 1 hour. The resulting solution was then filtered through a 325-mesh metal filter to obtain oil-free hydrogenated linear polybutadiene.

[0085] spectrum 1 H-NMR

[0086] The quantitative determination of the microstructure of hydrogenated linear polybutadiene based on the content of 1,2 configuration units was achieved through... 1 H-NMR spectra were performed using the internal standard method based on ISO 21561-1:2015.

[0087] Recordings were performed at 30°C using a high-resolution liquid-phase nuclear magnetic resonance spectrometer in mode, equipped with a 5 mm DUL 13C-1H / 2H Z-GRD probe and a temperature-variable accessory. 1 H-NMR spectrum.

[0088] For analysis, a polymer solution of non-hydrogenated polybutadiene (“parent polymer”) obtained as described in the following examples, at a concentration of 3% w / v (g / ml), was used, prepared using deuterated chloroform (CDCl3) (purity > 99.8%).

[0089] The operating conditions adopted are as follows:

[0090] Acquisition parameters (5 mm probe):

[0091] - Mode: Single pulse;

[0092] - Tilt angle (μs): 90° pulse;

[0093] - Temperature: 30℃;

[0094] - Number of data points: 64 k;

[0095] - Offset: 4.6 ppm;

[0096] - Scan width: 9 ppm;

[0097] - Pulse repetition: 10 seconds:

[0098] - Cumulative count: 64;

[0099] - Solvent: Deuterated chloroform (CDCl3) (Merck: Purity > 99.8%)

[0100] - Sample rotation: On.

[0101] calculate 1 H:

[0102] Integral IA: Olefin signal area associated with 1,2-polybutadiene units (4.3 ÷ 5.0 ppm);

[0103] Integral IB: Olefin signal area associated with 1,2-polybutadiene units and 1,4-polybutadiene units (5.0 ÷ 6.1 ppm)

[0104]

[0105] Molecular weight determination

[0106] The weight-average molecular weight (Mb) of hydrogenated polybutadiene, as reported in the following examples, was determined by GPC (“gel permeation chromatography”) using an Agilent Technologies Integrated 1200 Series instrument with RID detection, under the following conditions. w Number-average molecular weight (M) n ) and the Multidispersion Index (PDI) (M w / M n The determination of )

[0107] - Six Agilent Technologies GPC PL columns, each measuring 300 x 7.5 mm, consist of the following:

[0108] type Particle size Porosity (Å) PLGEL 5 μm <![CDATA[10 5 ]]> PLGEL 5 μm <![CDATA[10 5 ]]> PLGEL 5 μm <![CDATA[10 4 ]]> PLGEL 5 μm <![CDATA[10 3 ]]> PLGEL 10 μm <![CDATA[10 6 ]]> PLGEL 5 μm 500

[0109] - Mettler Toledo analyzes the balance scale;

[0110] - Laboratory glassware;

[0111] - Vibrating stirrer;

[0112] - Column injection temperature: 25℃;

[0113] - Column and detector temperature: 25°C;

[0114] - Solvent / eluent: Tetrahydrofuran (THF) (HPLC grade 99+% - Merck);

[0115] - Flow rate: 1 ml / min;

[0116] - Calculate molecular weight using a universal calibration curve.

[0117] The aforementioned operating conditions are continuously monitored via a personal computer equipped with Agilent Technologies' Agilent GPC / SEC software.

[0118] The calibration is performed as follows.

[0119] Four tetrahydrofuran (THF) solutions (HPLC grade 99+%-Merck) were prepared, each containing three nominal peak molecular weights (M). p Different polystyrene (PS) standards of the same concentration: The molecular weight was chosen to ensure good separation of the eluted chromatographic peaks. The aforementioned standards used for calibration curves have different nominal peak molecular weights (M). p The range is approximately 3 kDa to 1200 kDa.

[0120] Different solutions were prepared by stirring at room temperature (25°C).

[0121] Using a personal computer equipped with the aforementioned Agilent Technologies GPC / SEC software, a calibration curve is calculated using a third-order polynomial function: the aforementioned information related to molecular weight can be obtained through the polynomial.

[0122] Determination of degree of hydrogenation (GI)

[0123] The degree of hydrogenation (GI) of hydrogenated linear polybutadiene, as reported in the following examples, was determined by Fourier transform infrared spectroscopy (FTIR) using a THERMO FISHER NICOLETiS50 spectrophotometer with the following characteristics:

[0124] OMNIC software version 9.12;

[0125] Spectral range: 4000-400 cm⁻¹ -1 ;

[0126] Single beam;

[0127] Detector: TGS (triglycine deuterated sulfate).

[0128] The operating conditions adopted are as follows:

[0129] Measurement in projection mode;

[0130] Spectral range: 1050-650 cm⁻¹ -1 ;

[0131] Number of scans: 25;

[0132] Resolution: 4 cm -1 ;

[0133] Gain: 1;

[0134] The moving speed of the mirror in the interferometer: 0.6329 cm / s;

[0135] Slit opening: 65.

[0136] A certain amount of hydrogenated linear styrene-butadiene-styrene block copolymer (Europrene) ® A cyclohexane (Merck) solution (~10% w / w) of SOL TH2315 was added to each sample to be analyzed, as described below.

[0137] To calculate the calibration line, non-hydrogenated linear polybutadiene (“parent polymer”) used in the following examples and hydrogenated linear polybutadiene obtained from the examples were used.

[0138] For the aforementioned non-hydrogenated linear polybutadiene (“parent polymer”), it is necessary to determine the absorbance associated with the analyte functional group. Specifically, this is done under the following conditions:

[0139] Weigh 0.8 g of non-hydrogenated linear polybutadiene (“parent polymer”) into a 20 ml vial with a screw cap, then add 10 ml of cyclohexane (Merck) (~10% w / w), and place the whole vial in a shaker until completely dissolved.

[0140] - Add 5 ml of the resulting solution to 5 ml of hydrogenated linear styrene-butadiene-styrene block copolymer (Europrene). ® A cyclohexane (Merck) solution (10% by weight) of SOL TH 2315 was mixed to simulate the binding of a styrene-butadiene copolymer with a styrene content of approximately 15% by weight. The resulting mixture was stirred until completely mixed. A thin layer of the resulting polymer solution was spread on a rectangular window (40 × 20 mm, 5 mm thick) of potassium bromide using a glass rod, and the solvent was evaporated by a nitrogen stream.

[0141] - By 1050 cm -1 Up to 650 cm -1 The sample was scanned 25 times within the spectral range for background analysis. The background was subtracted from the IR spectrum of the sample to empty the sample chamber.

[0142] - By inserting a window along the IR beam path onto which the polymer solution is spread, the sample was scanned 25 times within the same spectral range (at 1050 cm⁻¹ for proper evaluation of the spectrum). -1The transmittance at a given point must be greater than 80%, and the strongest spectral band must be between 20% and 40%; if these conditions are not met, it is necessary to disregard the obtained values ​​and repeat the sample analysis.

[0143] - at approximately 968 cm -1 (At), 910 cm -1 (Av) and 700 cm -1 The maximum absorbance was measured at (As);

[0144] - For the "parent polymer", measure the ratio (At + Av) / As and record it on the y-axis where it equals 0; for the fully hydrogenated polymer, the ratio (At + Av) / As will equal 0; calculate the equation of the line y = aX + b interpolating between the two points (e.g., ...). Figure 1 (As shown).

[0145] The degree of hydrogenation is calculated using the following expression:

[0146]

[0147] in:

[0148] - Av = Vinyl absorbance (910 cm⁻¹) -1 );

[0149] - At = Absorbance of the trans structure (968 cm⁻¹) -1 );

[0150] - As = absorbance of styrene (700 cm⁻¹) -1 );

[0151] - a = the angle coefficient of the line;

[0152] - b = the intercept of the line on the ordinate axis.

[0153] Determination of enthalpy of crystallization (ΔHc)

[0154] The enthalpy of crystallization (ΔHc) was determined using a TA Instruments Discovery DSC 2500 differential scanning calorimeter via temperature modulated differential scanning calorimetry (TMDSC).

[0155] For the theoretical basis of temperature modulated differential scanning calorimetry (TMDSC), refer to the report by Simon SL in "Thermochimica Acta" (2001), Vol. 374, pp. 55-71.

[0156] The temperature-modulated differential scanning calorimetry (TMDSC) enables the differentiation of glass transition / melting / crystallization types within the same temperature range according to the equations reported below:

[0157] =Cp +f(T,t)

[0158] in:

[0159] - H is the total heat flux [W / g], H is the enthalpy per unit mass [J / g], and t is the time [s].

[0160] - Cp is the specific heat under constant pressure. (Heat capacity);

[0161] - Heating rate ;

[0162] - Cp It is a reversible heat flow [W / g];

[0163] - f(T,t) is the irreversible heat flow [W / g].

[0164] For this purpose, in order to determine the glass transition temperature (T g ), crystallization temperature (T) c The temperature modulated differential scanning calorimetry (TMDSC) was performed on hydrogenated linear polybutadiene samples obtained as reported in the following examples, and the enthalpy of crystallization (ΔHc).

[0165] - Sample conditioning: Heat from T=23±1℃ to T=+100℃, then hold at T=+100℃ for 5 minutes;

[0166] - Using TMDSC (i.e., modulated DSC) at a rate of + / - 0.47°C every 60 seconds, the temperature was programmed to cool from T = +100°C to T = -100°C at a rate of v = 3°C / min.

[0167] Where T = temperature; v = scanning speed.

[0168] Determination of dynamic viscosity of hydrogenated linear polybutadiene

[0169] Dynamic viscosity was measured using an Anton Paar MCR 702 controlled stress rotational rheometer equipped with a smooth parallel plate geometry (40 mm in diameter, PP40).

[0170] For the theoretical foundations of rheology and the best practices required for the accurate measurement of dynamic viscosity using a rotational rheometer equipped with parallel plates, refer to Macosko W. in “Rheology: Principles, Measurements, and Applications” (1994), Whiley-VCH Inc., Chapter 5, pp. 217-220.

[0171] Dynamic viscosity measurements were performed at temperatures of 40°C, 80°C, 100°C, 120°C, and 150°C. The rheometer software was Rheocompass version 1.31, release number 43. A zero-gap procedure (i.e., zeroing the inter-plate distance) was performed at T = 100°C. The rheometer is capable of compensating for thermal expansion of the measurement accessories due to temperature variations. The thermal expansion of the accessories was calibrated using a procedure provided by Anton Paar, which is available in the Rheocompass software used.

[0172] Use a Peltier temperature control system (model C-PTD200 + H-PTD200) equipped with a convection shroud to ensure the correct analysis temperature. Allow 20 minutes for temperature stabilization at each analysis temperature.

[0173] Record the viscosity value in the steady state 100 seconds after the stress is applied to eliminate the influence of the initiation viscoelastic transient.

[0174] Tests were conducted under various shear stress settings (from 0.1 Pa to 320 Pa) to verify the potential non-Newtonian behavior of the material. To avoid problems caused by flow instability, the maximum extreme shear rate applied was equal to 10 s⁻¹. -1 .

[0175] Determination of target concentration in base oil

[0176] For this purpose, the obtained hydrogenated linear polybutadiene was dissolved in a variable amount to obtain a target dynamic viscosity in a Group III 4 cSt base oil (Yubase 4-SK Lubricant), which is equivalent to the viscosity of ethylene-propylene copolymer (Dutral) at a concentration of 1 wt% in the same Group III 4 cSt base oil. ® The dynamic viscosity of the solution of OCP 2550 (Versalis SpA) was measured using an Antoon Paar SVM 3000 rotational viscometer according to ASTM D-7042-04.

[0177] Determination of Shear Stability Index (SSI)

[0178] For this purpose, hydrogenated linear polybutadiene obtained as reported in the following examples was dissolved in a Group III 4 cSt base oil (Yubase 4-SK Lubricant) at an amount equal to the target concentration.

[0179] The shear stability index (SSI) was determined according to the CEC-L-14-A-93 standard (30 shear cycles).

[0180] Pour point determination

[0181] For this purpose, hydrogenated linear polybutadiene obtained as reported in the following examples was dissolved in a Group III 4 cSt base oil (Yubase 4-SK Lubricant) at an amount equal to the target concentration, and an additive Viscoplex of 0.2% by weight relative to the total weight of the solution was added to the resulting solution. ® V1-254 (Evonik) (“Pour Point Depressant” - PPD).

[0182] Pour point is measured according to ASTM D7346-15 standard.

[0183] Determination of viscosity index

[0184] For this purpose, the hydrogenated linear polybutadiene obtained as reported in the following examples was dissolved in a Group III 4 cSt base oil (Yubase 4-SK Lubricant) at an amount equal to the target concentration and the viscosity index was measured according to ASTM D2270-95.

[0185] Examples 1 and 3-5 (of the present invention)

[0186] Preparation of hydrogenated linear polybutadiene

[0187] Four types of hydrogenated linear polybutadiene were prepared by the following procedures.

[0188] The discontinuous (batch) solution polymerization reaction was carried out in an 18.5 L batch reactor (16 L of which is the effective volume), which was equipped with impeller blades, an anchor-type bottom scraper, a bottom discharge port and a heating jacket.

[0189] Anhydrous cyclohexane (Cepsa) is fed into the reactor, and after the temperature reaches 35°C, tetrahydrofuran (THF) (VWR International) is added, followed by the following reaction:

[0190] Aggregation [(step(a))]

[0191] - Add anhydrous 1,3-butadiene (Versalis SpA);

[0192] - Add n-butyllithium (15% hexane solution) (Merck) (NBL);

[0193] - Waiting for reaction time;

[0194] Termination of step (b)

[0195] - Add trimethylchlorosilane (CH3SiCl) (Merck) [step (b)];

[0196] - Waiting for reaction time;

[0197] Hydrogenation [(Step (c))]

[0198] - Add butyl ethyl magnesium chloride (14% heptane solution) (Nouryon);

[0199] - Added bis(cyclopentadienyl)titanium dichloride (Nouryon);

[0200] - Waiting for response time.

[0201] At the end of hydrogenation step (c), the mixture obtained is subjected to a desolventization step (d) in the absence of water by means of a stirred thin-film evaporator operating at a pressure of 35 mbar and a temperature of 170°C.

[0202] Table 1 reports the operating conditions used: the compound fed into the reactor, the temperature, and the reaction duration.

[0203] The obtained hydrogenated linear polybutadiene was characterized as described above, and the results are reported in Table 2.

[0204] Example 2 (Invention)

[0205] Oil solution for preparing hydrogenated linear polybutadiene

[0206] An oil solution of hydrogenated linear polybutadiene was prepared by the following procedure.

[0207] The discontinuous (batch) solution polymerization reaction is carried out in a 1 L batch reactor (where 0.8 L is the effective volume), which is equipped with impeller blades, a bottom discharge port and a heating jacket.

[0208] The reactor was fed with Group III 4 cSt base oil (Yubase 4-SK Lubricant), and after the temperature reached 60°C, tetrahydrofuran (THF) (VWR International) was added, followed by the following reaction:

[0209] Aggregate [(step(a'))]

[0210] - Add anhydrous 1,3-butadiene (Versalis SpA);

[0211] - Add n-butyllithium (15% hexane solution) (Merck) (NBL);

[0212] - Waiting for reaction time;

[0213] Terminate [step (b')]

[0214] - Add trimethylchlorosilane (CH3SiCl) (Merck) [step (b')];

[0215] - Waiting for reaction time;

[0216] Hydrogenation [(Step (c'))]

[0217] - Add butyl ethyl magnesium (14% heptane solution) (Nouryon);

[0218] - Added bis(cyclopentadienyl)titanium dichloride (Nouryon);

[0219] - Waiting for response time.

[0220] Table 1 reports the operating conditions used: the compound fed into the reactor, the temperature, and the reaction duration.

[0221] The obtained hydrogenated linear polybutadiene was characterized as described above, and the results are reported in Table 2.

[0222] Examples 6-8 (Comparative)

[0223] Preparation of hydrogenated linear polybutadiene

[0224] Three types of hydrogenated linear polybutadiene were prepared by the following procedures.

[0225] The discontinuous (batch) solution polymerization reaction was carried out in an 18.5 L batch reactor (16 L of which is the effective volume), which was equipped with impeller blades, an anchor-type bottom scraper, a bottom discharge port and a heating jacket.

[0226] Anhydrous cyclohexane (Cepsa) is fed into the reactor, and after the temperature reaches 35°C, tetrahydrofuran (THF) (VWR International) is added, followed by the following reaction:

[0227] Aggregation [(step(a))]

[0228] - Add anhydrous 1,3-butadiene (Versalis SpA);

[0229] - Add n-butyllithium (15% hexane solution) (Merck) (NBL);

[0230] - Waiting for reaction time;

[0231] Termination of step (b)

[0232] - Add trimethylchlorosilane (CH3SiCl) (Merck) [step (b)];

[0233] - Waiting for reaction time;

[0234] Hydrogenation [(Step (c))]

[0235] - Add butyl ethyl magnesium chloride (14% heptane solution) (Nouryon);

[0236] - Added bis(cyclopentadienyl)titanium dichloride (Nouryon);

[0237] - Waiting for response time.

[0238] At the end of hydrogenation step (c), the resulting mixture is subjected to a desolventizing step (d) in the presence of water, as described below.

[0239] The resulting mixture is discharged from the bottom of the reactor and conveyed to a storage container. Subsequently, the mixture is continuously conveyed to a stripping tower containing water at 90°C, in which steam is also conveyed to obtain stripping of unreacted monomers (1,3-butadiene and styrene) and solvent: in fact, solvent removal is not possible by means of a stirred thin-film evaporator due to the high viscosity of the polymer.

[0240] The water leaving the stripping tower is collected and transported to water treatment.

[0241] Table 1 reports the operating conditions used: the compound fed into the reactor, the temperature, and the reaction duration.

[0242] The obtained hydrogenated linear polybutadiene was characterized as described above, and the results are reported in Table 2.

[0243] Table 1

[0244]

[0245]

[0246] Table 2

[0247]

[0248] (1) : % by weight relative to the total weight of butadiene units in hydrogenated linear polybutadiene [% by weight, determined for non-hydrogenated linear polybutadiene (“parent polymer”)];

[0249] (2) Not determined because the sample was in a semi-crystalline state at 40°C.

Claims

1. A lubricating oil viscosity index improver (VII) additive comprising hydrogenated linear polybutadiene, wherein the hydrogenated linear polybutadiene has the following characteristics: - Weight-average molecular weight (M w The range is from 1,000 Daltons to 40,000 Daltons, preferably from 1,500 Daltons to 38,000 Daltons; - The content of units having configuration 1,2 is 40% to 80% by weight, preferably 45% to 75% by weight, relative to the total amount of butadiene units present in the hydrogenated linear polybutadiene; - Polydispersity Index (PDI), i.e., weight-average molecular weight (M). w ) and number-average molecular weight (M n The ratio of (M) w / M n The value is less than or equal to 1.3, preferably 1 to 1.1; - The degree of hydrogenation is greater than or equal to 98%, preferably 98.5% to 100%; - The dynamic viscosity measured at 40°C is from 5 Pa*s to 10000 Pa*s, preferably from 10 Pa*s to 8000 Pa*s; - The dynamic viscosity measured at 100°C is from 0.1 Pa*s to 1000 Pa*s, preferably from 0.2 Pa*s to 500 Pa*s; - The enthalpy of crystallization (ΔHc) determined by temperature-modulated differential scanning calorimetry (TMDSC) is 0 J / g to 1 J / g, preferably 0 J / g to 0.8 J / g.

2. The lubricating oil viscosity index improver (VII) additive containing hydrogenated linear polybutadiene according to claim 1, has the following characteristics: - The shear stability index (SSI) is 0% to 7%, preferably 0% to 5%, and is measured in Group III 4 cSt base oils according to CEC-L-14-A-93 standard (30 shear cycles); - Pour point below or equal to -30°C, preferably -33°C to -45°C, with the addition of Viscoplex ® Measurements were performed in Group III 4 cSt base oils in the presence of V1-254 (Evonik) (pour point reducer - PPD) according to ASTM D5950-14.

3. The lubricating oil viscosity index improver (VII) additive comprising hydrogenated linear polybutadiene according to claim 1 or 2, wherein, in order to achieve a target dynamic viscosity of 6 to 9 cSt, preferably 7 to 8 cSt, measured in a Group III 4 cSt base oil according to ASTM D7042-04 at 100°C, the lubricating oil viscosity index improver (VII) is applied to the Group III 4 cSt base oil at a target concentration of 1.9% to 12% by weight, preferably 2.1% to 10% by weight, relative to the total weight of the Group III 4 cSt base oil and the viscosity index improver (VII) in the lubricating oil composition.

4. A discontinuous (batch) method for preparing hydrogenated linear polybutadiene, comprising the following steps: (a) 1,3-Butadiene is subjected to living polymerization via an anionic pathway in the presence of at least one hydrocarbon solvent, at least one lithium-based initiator and at least one polar modifier, and the polymerization is continued until the 1,3-butadiene is substantially completely converted. (b) Add at least one terminating agent to the polymerization mixture obtained in step (a); (c) Hydrogenate the linear polybutadiene obtained in step (b) to obtain a mixture containing hydrogenated linear polybutadiene; (d) The mixture containing hydrogenated linear polybutadiene obtained in step (c) is subjected to desolventizing treatment, and the hydrogenated linear polybutadiene is recovered; The desolventizing step (d) is carried out in the absence of water.

5. The discontinuous (intermittent) method for preparing hydrogenated linear polybutadiene according to claim 4, wherein: - The at least one hydrocarbon solvent is selected from aliphatic, alicyclic, or aromatic hydrocarbon solvents, such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, n-heptane, n-octane, cyclohexane, cyclopentane, propylene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, or mixtures thereof, preferably in anhydrous form; it is preferably selected from anhydrous cyclohexane, n-hexane, or mixtures thereof; and / or - The at least one lithium-based initiator is selected from compounds having general formula (I): R1(Li) n (I) Where R1 represents a straight-chain or branched alkyl group C1-C. 20 C2-C is preferred. 12 cycloalkyl C3-C 30 C4-C is preferred. 10 aryl C6-C 30 C6-C is preferred. 12 And n is an integer from 1 to 4; preferably: methyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, n-propyllithium, isobutyllithium, pentyllithium, cyclohexyllithium, phenyllithium, 1-methylstyryllithium, p-tolyllithium, naphthyllithium, L,L-diphenyl-5-lithium-3-methyl-pentyl or mixtures thereof; more preferably it is n-butyllithium; and / or - The at least one polar modifier is selected from: noncyclic ethers, such as diethyl ether or mixtures thereof; Tertiary amines, such as tributylamine; cyclic ethers, such as tetrahydrofuran (THF); chelating ethers, such as ethylene glycol dimethyl ether (dimethyl glycol dimethyl ether), dioxane, 2-methoxy-ethyl-tetrahydrofuran (THFA-ethyl), 2-methoxy-ethyl-tetrahydropyran, or mixtures thereof; chelating amines, such as N,N,N',N'-tetramethylenediamine (TMEDA); or mixtures thereof; preferably, it is selected from tetrahydrofuran (THF), 2-methoxy-ethyl-tetrahydrofuran (THFA-ethyl), or mixtures thereof; and / or - The at least one terminating agent is selected from trimethylchlorosilane, butanol, octanol or a mixture thereof; preferably it is trimethylchlorosilane.

6. The discontinuous (intermittent) method for preparing hydrogenated linear polybutadiene according to claim 4 or 5, wherein: - Step (a) is performed at a temperature of 20°C to 100°C, preferably 25°C to 85°C; and / or for a time of 10 minutes to 1 hour, preferably 15 minutes to 40 minutes; and / or - Step (b) is performed at a temperature of 30°C to 115°C, preferably 40°C to 110°C; and / or for a time of 1 minute to 30 minutes, preferably 3 minutes to 20 minutes.

7. A discontinuous ("intermittent") method for preparing hydrogenated linear polybutadiene via an anionic route, comprising the following steps: (a') 1,3-Butadiene is subjected to living polymerization via an anionic pathway in the presence of at least one lubricating base oil, at least one lithium-based initiator and at least one polar modifier, and the polymerization is continued until the 1,3-butadiene is substantially completely converted. (b') Add at least one terminating agent to the polymerization mixture obtained in step (a'); (c') Hydrogenate the linear polybutadiene obtained in step (b') to obtain a mixture containing hydrogenated linear polybutadiene.

8. The discontinuous ("intermittent") method for preparing hydrogenated linear polybutadiene via an anionic route according to claim 7, wherein: - Step (a') is performed at a temperature of 20°C to 100°C, preferably 25°C to 85°C; and / or for a time of 10 minutes to 1 hour, preferably 20 minutes to 40 minutes; and / or - Step (b') is performed at a temperature of 30°C to 115°C, preferably 40°C to 110°C; and / or for a time of 1 minute to 30 minutes, preferably 3 minutes to 20 minutes.

9. The discontinuous ("intermittent") method for preparing hydrogenated linear polybutadiene via an anionic route according to claim 7 or 8, wherein: - The at least one lithium-based initiator, at least one polar modifier, and at least one terminator are selected from those mentioned in claim 5; and / or - The at least one lubricating base oil is selected from mineral-derived, synthetic-derived lubricating base oils or mixtures thereof.

10. A concentrated solution comprising, in at least one lubricating base oil, at least one lubricating oil viscosity index improver (VII) additive comprising hydrogenated linear polybutadiene according to any one of the preceding claims, wherein the lubricating base oil is selected from mineral-derived, synthetic-derived lubricating base oils or mixtures thereof.

11. A lubricating oil composition comprising at least one lubricating base oil and at least one lubricating oil viscosity index improver (VII) additive comprising hydrogenated linear polybutadiene according to any one of claims 1 to 9, wherein the lubricating base oil is selected from mineral-derived, synthetic-derived lubricating base oils or mixtures thereof, and the additive is present in the lubricating oil composition in an amount of 0.5% to 50% by weight, preferably 1% to 35% by weight, relative to the total weight of the lubricating oil composition.

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